IEEE Standard for Ratings and Requirements for AC High-Voltage … · 2020. 12. 16. · IEEE 3 Park Avenue New York, NY 10016-5997 USA IEEE Power and Energy Society IEEE Std C37.04™-2018

IEEE Standard for Ratings and Requirements for AC High-Voltage Circuit Breakers with Rated Maximum Voltage Above 1000 V

Sponsored by the Switchgear Committee

IEEE 3 Park Avenue New York, NY 10016-5997 USA

IEEE Power and Energy Society

IEEE Std C37.04™-2018 (Revision of

IEEE Std C37.04-1999)

Authorized licensed use limited to: AALTO UNIVERSITY. Downloaded on June 08,2019 at 11:53:30 UTC from IEEE Xplore. Restrictions apply.

IEEE Std C37.04™-2018 (Revision of

IEEE Std C37.04-1999)


Sponsor Switchgear Committee of the IEEE Power and Energy Society Approved 5 December 2018 IEEE-SA Standards Board


Abstract: The rating structure for all high-voltage circuit breakers, which include all voltage ratings above 1000 V ac and comprise both indoor and outdoor types, is covered in this standard. Preferred ratings are also provided. Typical circuit breakers covered by these standards have maximum voltage ratings ranging from 4.76 kV through 800 kV, and continuous current ratings of 600 A, 1200 A, 2000 A, 3000 A, and 4000 A associated with the various maximum voltage ratings. The rating structure establishes the basis for all assigned ratings, including continuous current, insulation capability (formerly dielectric withstand voltages), short-circuit current, transient recovery voltage, and capacitor switching, plus associated capabilities such as mechanical endurance, load current, and out-of-phase switching. Generator circuit breakers are covered by IEC/IEEE Std 62271-37-013. Keywords: capacitive current switching, IEEE C37.04™, indoor, insulation capability, interrupting time, mechanical endurance, outdoor, operating duty, power frequency, ratings, related capabilities, short-circuit current, short-line fault, transient recovery voltage

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Introduction

This introduction is not part of IEEE Std C37.04-2018, IEEE Standard for Ratings and Requirements for AC High-Voltage Circuit Breakers with Rated Maximum Voltage Above 1000 V.

In 1964, consolidated standards for circuit breakers rated on a symmetrical current basis were published to take the place of standards established on the total current basis of rating. This revision was undertaken to update the standard to reflect today’s circuit breaker technology and application on modern power systems. The revision also continues harmonization with IEC 62271-100, a process that first began in 1951.

This revision includes the changes introduced into capacitive switching ratings and harmonization of TRV requirements of amendments 1 and 2 to IEEE Std C37.04-1999, IEEE Std C37.04a™-2003, and IEEE Std C37.04b™-2008 as well as all corrigenda and errata. The major change in this edition of IEEE Std C37.04 is the incorporation of the preferred ratings values from IEEE Std C37.06™-2009 [B24] into this document. With the approval of this edition of IEEE Std C37.04™-1999 [B23], IEEE Standards Association Standards Board action will withdraw IEEE Std C37.06-2009.

This revision does not make major changes to requirements that have been in practice. Revisions have been made to incorporate information that was offered to IEEE by the NEMA SG4 (High-Voltage Circuit Breakers) technical committee. With some exceptions, this new material has been incorporated essentially as received from NEMA. The areas covered by the NEMA material include new definitions related to pressure systems and noise, new requirements for flat terminals, ground terminals, additional requirements for various operating mechanisms, enclosures, wiring, noise, X-radiation for vacuum interrupters, current transformers (and their connections) (including free-standing current transformers), undervoltage trip devices, and specialized applications.

The reader is reminded that these requirements do not apply retroactively. Circuit breakers designed, tested, and manufactured to earlier versions of the standards must be applied in accordance with the versions of the standards that were in effect when the specific circuit breaker was manufactured.



Participants

At the time this IEEE standard was completed, the High-Voltage Circuit Breaker Standard Working Group had the following membership:

Stephen Cary, Chair Roy Alexander, Vice Chair John C. Webb, Secretary

Brad Armstrong David Lemmerman Mauricio Aristizabal Anne Bosma Arben Bufi Ted Burse Eldridge Byron Steven Chen Chih Chow Michael Christian Lucas Collette Michael Crawford Patrick Di Lillo Jeffrey Door Denis Dufournet Robert Foster Raymond Frazier Paul Grein John Hall

Helmut Heiermeier Christian Heinrich Jeremy Hensberger Victor Hermosillo Jennifer Hunter Roy Hutchins Todd Irwin Cory Johnson Thomas Keels Scott Lanning Brad Leccia Hua Ying Liu Albert Livshitz Vincent Marshall Gary Martin Peter Marzec Dave Mitchell Charles Morse

Tom Mulcahy Miklos Orosz Andrew Peterson John Phouminh Samala Santosh Reddy Anthony Ricciuti Daniel Schiffbauer Carl Schuetz Devki Sharma Sushil Shinde Dean Sigmon Michael Skidmore Vernon Toups Jim van de Ligt Jan Weisker Terrance Woodyard Richard York Wei Zhang Xi Zhu

The following members of the individual balloting committee voted on this standard. Balloters may have voted for approval, disapproval, or abstention.

William Ackerman Roy Alexander Mauricio Aristizabal Roy Ayers Thomas Barnes G. Bartok Robert Beavers Robert Behl W. J. (Bill) Bergman Stan Billings Wallace Binder William Bloethe Anne Bosma Steven Brown John Brunke Arben Bufi Ted Burse Eldridge Byron Thomas Callsen Paul Cardinal Stephen Cary Steven Chen Michael Chirico Chih Chow Robert Cohn Lucas Collette

Michael Crawford Gary Donner Denis Dufournet Edgar Dullni Douglas J. Edwards Kenneth Edwards Tanner Esco Leslie Falkingham Sergio Flores Paul Forquer Kenneth Gettman David Giegel Douglas Giraud Mietek Glinkowski Robert Goodin Edwin Goodwin James Graham Lou Grahor Randall Groves John Harley Ronald Hartzel Helmut Heiermeier Werner Hoelzl William Hurst Todd Irwin Richard Jackson

Laszlo Kadar Chad Kennedy Yuri Khersonsky James Kinney Boris Kogan Jim Kulchisky Carl Laplace Hua Liu Albert Livshitz R Long William McBride Neil Mc Cord Peter Meyer David Mitchell Charles Morse Thomas Mulcahy Jeffrey Nelson Michael Newman Joe Nims T. W. Olsen Lorraine Padden Shawn Patterson Andrew Peterson Anthony Picagli Iulian Profir Farnoosh Rahmatian



Reynaldo Ramos Samala Santosh Reddy Anthony Ricciuti Charles Rogers Tim Rohrer Thomas Rozek Ryandi Ryandi Steven Sano Roderick Sauls Bartien Sayogo Daniel Schiffbauer Carl Schuetz Devki Sharma

Xu She Sushil Shinde John Shullaw Michael Sigmon Michael Skidmore Jeremy Smith Jerry Smith R. Kirkland Smith Ralph Stell Donald Swing David Tepen Malcolm Thaden Marcelo Valdes

Jim van de Ligt John Vergis Michael Wactor John Wang John Webb Jan Weisker Kenneth White Terry Woodyard Larry Yonce Richard York Jian Yu Matthew Zeedyk Xi Zhu

When the IEEE-SA Standards Board approved this standard on 5 December 2018, it had the following membership:

Jean-Philippe Faure, Chair Gary Hoffman, Vice Chair John D. Kulick, Past Chair

Konstantinos Karachalios, Secretary

Ted Burse Guido R. Hiertz Christel Hunter Joseph L. Koepfinger* Thomas Koshy Hung Ling Dong Liu

Xiaohui Liu Kevin Lu Daleep Mohla Andrew Myles Paul Nikolich Ronald C. Petersen Annette D. Reilly

Robby Robson Dorothy Stanley Mehmet Ulema Phil Wennblom Philip Winston Howard Wolfman Jingyi Zhou

*Member Emeritus



Contents

1. Scope ........................................................................................................................................................ 11

2. Normative references ................................................................................................................................ 11

3. Definitions, acronyms, and abbreviations ................................................................................................ 13 3.1 Definitions ......................................................................................................................................... 13 3.2 Acronyms and abbreviations ............................................................................................................. 15

4. Service conditions .................................................................................................................................... 16 4.1 Usual service conditions .................................................................................................................... 16 4.2 Unusual service conditions ................................................................................................................ 18

5. Descriptions of ratings and capabilities .................................................................................................... 19 5.1 General .............................................................................................................................................. 19 5.2 Rated maximum voltage (V) or (Ur) .................................................................................................. 20 5.3 Rated insulation capability ................................................................................................................ 20 5.4 Rated power-frequency (fr) ................................................................................................................ 22 5.5 Rated continuous (normal) current (Ir) .............................................................................................. 22 5.6 Rated short-circuit current and related required capabilities ............................................................. 25 5.7 Transient recovery voltage (TRV) ..................................................................................................... 28 5.8 Rated capacitive current switching .................................................................................................... 36 5.9 Assigned out-of-phase switching current rating ................................................................................ 38 5.10 Rated standard operating duty (standard duty cycle) ....................................................................... 39 5.11 Rated control voltage ....................................................................................................................... 40 5.12 Rated operating pressure for insulation and/or interruption ............................................................ 40 5.13 Rated operating pressure for mechanical operation and special capabilities ................................... 40

6. Preferred ratings ....................................................................................................................................... 41 6.1 General .............................................................................................................................................. 41 6.2 Preferred maximum voltage and insulation capability ratings for circuit breakers ........................... 43 6.3 Preferred ratings for class S1 circuit breakers ................................................................................... 47 6.4 Preferred ratings for class S2 circuit breakers for line systems below 100 kV .................................. 52 6.5 Preferred ratings for circuit breakers 100 kV and above ................................................................... 58 6.6 Rated reclosing times for circuit breakers ......................................................................................... 69 6.7 Control voltage ranges for circuit breakers ........................................................................................ 69 6.8 Circuit breaker operation and operating endurance capabilities ........................................................ 71

7. Construction and functional components ................................................................................................. 72 7.1 Requirements for liquids in switchgear ............................................................................................. 72 7.2 Requirements for gases in circuit breakers ........................................................................................ 73 7.3 Grounding .......................................................................................................................................... 73 7.4 Auxiliary and control equipment ....................................................................................................... 73 7.5 Operating mechanisms....................................................................................................................... 75 7.6 Alternative operating mechanisms ..................................................................................................... 78 7.7 Low- and high-pressure interlocking and monitoring devices ........................................................... 79 7.8 Degrees of protection by enclosures .................................................................................................. 79 7.9 Enclosure and wiring requirements ................................................................................................... 80 7.10 Creepage distances .......................................................................................................................... 80 7.11 Gas and vacuum tightness ............................................................................................................... 80 7.12 Liquid tightness ............................................................................................................................... 81 7.13 Noise requirements .......................................................................................................................... 81 7.14 Electromagnetic compatibility (EMC) ............................................................................................. 83 7.15 Vacuum interrupters and X-Ray emission ....................................................................................... 83



7.16 Radio influence voltage limits ......................................................................................................... 83 7.17 Requirements for terminals and bushings used on outdoor or free standing circuit breakers .......... 84 7.18 Circuit breaker mechanical loading ................................................................................................. 84 7.19 Pressurized components ................................................................................................................... 86 7.20 Pressurized systems ......................................................................................................................... 86 7.21 Requirements for simultaneity of poles ........................................................................................... 87

8. Nameplate markings ................................................................................................................................. 87 8.1 Circuit breaker ................................................................................................................................... 87 8.2 External insulation ............................................................................................................................. 88 8.3 Operating mechanism ........................................................................................................................ 88 8.4 Current transformer and linear coupler nameplates ........................................................................... 89 8.5 Accessories ........................................................................................................................................ 90 8.6 Instructions and warning signs .......................................................................................................... 90

9. Current transformers ................................................................................................................................. 90 9.1 General .............................................................................................................................................. 90 9.2 Ratings ............................................................................................................................................... 90 9.3 Polarity and lead marking .................................................................................................................. 92 9.4 Undervoltage trip device .................................................................................................................... 96 9.5 Specialized Applications ................................................................................................................... 96

Annex A (informative) Bibliography ........................................................................................................... 97

Annex B (informative) Transient recovery voltage (TRV) .......................................................................... 99 B.1 TRV basics ........................................................................................................................................ 99 B.2 Rated TRV parameters ...................................................................................................................102 B.3 TRV Symbols used in the tables with the two-parameter method ...................................................107 B.4 Symbols used in tables with four-parameter method .......................................................................109

Annex C (normative) Exposure to pollution...............................................................................................113 C.1 General .............................................................................................................................................113 C.2 Pollution levels .................................................................................................................................113 C.3 Minimum requirements for switchgear ............................................................................................113

Annex D (informative) AC arc furnace switching .......................................................................................116 D.1 Repetitive duty circuit breakers for AC arc furnace switching ........................................................116 D.2 Servicing ..........................................................................................................................................116 D.3 Circuit conditions .............................................................................................................................116 D.4 Operating conditions ........................................................................................................................116 D.5 Conditions of the circuit breaker ......................................................................................................116 D.6 Minimum operations under fault conditions ....................................................................................116 D.7 Schedules .........................................................................................................................................117

Annex E (informative) Free standing current transformers .........................................................................118 E.1 Rated primary and secondary current ...............................................................................................118 E.2 Polarity lead markings ......................................................................................................................118 E.3 Secondary leads and terminations ....................................................................................................118 E.4 Primary terminal connection mechanical loading ............................................................................118 E.5 Typical connection of secondary burdens ........................................................................................118 E.6 Test procedures ................................................................................................................................118 E.7 Production tests ................................................................................................................................119

Annex F (normative) Extended electrical endurance (class E2) ..................................................................120 F.1 General .............................................................................................................................................120




1. Scope

This standard applies to ac high-voltage circuit breakers with rated nominal voltage above 1000 V. It establishes a rating structure, preferred ratings, construction and functional component requirements.

This standard encompasses the following:

⎯ Three pole circuit breakers used in three-phase systems

⎯ Single pole circuit breakers used in single-phase systems

⎯ Attachments for these circuit breakers, such as bushings, current transformers, interlocks, shunt trips, etc., and auxiliary equipment sold with the circuit breakers such as closing relays and structural steel supports.

This standard does not cover circuit breakers used at frequencies other than 50 Hz or 60 Hz or generator circuit breakers that are covered in IEC/IEEE Std 62271-37-013 [B14].

2. Normative references

The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.

ANSI C37.85, American National Standard for Switchgear—Alternating-Current High-Voltage Power Vacuum Interrupters—Safety Requirements for X-Radiation Limits.1

ASME Boiler and Pressure Vessel Code, Section VIII, Pressure Vessels.2

ASME Boiler and Pressure Vessel Code, Section X, Fiber-Reinforced Plastic Pressure Vessels.

1 ANSI publications are available from the American National Standard Institute (http://www.ansi.org). 2 ASME publications are available from the American Society of Mechanical Engineers (http://www.asme.org/).


IEEE Std C37.04-2018 IEEE Standard for Ratings and Requirements for AC High-Voltage Circuit Breakers

with Rated Maximum Voltage Above 1000 V


ASTM D2472, Standard Specification for Sulfur Hexafluoride.3

ASTM D3487, Standard Specification for Mineral Insulating Oil Used in Electrical Apparatus.

IEC 60529, Degrees of Protection Provided by Enclosures (IP Code).4

IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating-current circuit breakers.

IEC 62271-100:2008/AMD1:2012, Amendment 1 – High-voltage switchgear and controlgear – Part 100: Alternating-current circuit breakers.

IEC 62271-100:2008/AMD2:2017, Amendment 2 – High-voltage switchgear and controlgear – Part 100: Alternating-current circuit breakers.

IEC/TS 62271-304, High-voltage switchgear and controlgear – Part 304: Design classes for indoor enclosed switchgear and controlgear for rated voltages above 1 kV up to and including 52 kV to be used in severe climatic conditions.

IEEE Std 1™, IEEE Recommended Practice—General Principles for Temperature Limits in the Rating of Electrical Equipment and for the Evaluation of Electrical Insulation.5, 6

IEEE Std 4™, IEEE Standard for High-Voltage Testing Techniques.

IEEE Std C37.09™, IEEE Standard Test Procedures for AC High-Voltage Circuit Breakers with Rated Maximum Voltage Above 1000 V.

IEEE Std C37.010™, IEEE Application Guide for AC High-Voltage Circuit Breakers > 1000 Vac Rated on a Symmetrical Current Basis.

IEEE Std C37.017™, IEEE Standard for Bushings for High-Voltage [over 1000 V (ac)] Circuit Breakers and Gas-Insulated Switchgear.

IEEE Std C37.11™, IEEE Standard Requirements for Electrical Control for AC High-Voltage (>1000 V) Circuit Breakers.

IEEE Std C37.20.2™, IEEE Standard for Metal-Clad Switchgear.

IEEE Std C37.20.3™, IEEE Standard for Metal-Enclosed Interrupter Switchgear (1 kV–38 kV).

IEEE Std C37.20.10™, IEEE Standard Definitions for AC (52 kV and below) and DC (3.2 kV and below) Switchgear Assemblies.

IEEE Std C37.100.1-2007™, IEEE Standard of Common Requirements for High-Voltage Power Switchgear Rated Above 1000 V.

IEEE Std C37.100.5™, IEEE Standard for Definitions of High-Voltage Circuit Breakers Above 1000 Vac and 3200 Vdc, and Reclosers and Other Distribution Equipment from 1000 Vac to 38 000 Vac.

IEEE Std C57.13™, IEEE Standard Requirements for Instrument Transformers.

3 ASTM publications are available from the American Society for Testing and Materials (http://www.astm.org/). 4 IEC publications are available from the International Electrotechnical Commission (http://www.iec.ch/) and the American National Standards Institute (http://www.ansi.org). 5 The IEEE standards or products referred to in this clause are trademarks of The Institute of Electrical and Electronics Engineers, Inc. 6 IEEE publications are available from The Institute of Electrical and Electronics Engineers (http://standards.ieee.org/).


http://standards.ieee.org/




IEEE Std C57.106™, IEEE Guide for Acceptance and Maintenance of Insulating Mineral Oil in Electrical Equipment.

ISO 7000, Graphical symbols for use on equipment—Registered symbols.7

NEMA CC 1, Electric Power Connection for Substations.8

NEMA 107, Methods of Measurement of Radio Influence Voltage (RIV) of High-Voltage Apparatus.

3. Definitions, acronyms, and abbreviations

3.1 Definitions

For the purposes of this document, the following terms and definitions apply. The IEEE Standards Online Dictionary should be referenced for terms not defined in this clause.9

The terms and definitions applicable to this standard and to the related standards for ac high-voltage circuit breakers shall be in accordance with IEEE Std C37.20.10 and IEEE Std C37.100.5. These definitions are not intended to embrace all possible meanings of the terms. They are intended solely to establish the meanings of terms used in power switchgear.

air system (for pneumatic operating mechanism): An assembly of parts and devices that provide compressed air for the operation of a circuit breaker or circuit breaker operating mechanism.

amplitude factor (of transient recovery voltage): The ratio of the highest peak of the transient recovery voltage to the peak value of the normal-frequency recovery voltage.

NOTE—In tests made under one condition to simulate duty under another, as in single-phase tests made to simulate duty on three-phase ungrounded faults, the amplitude factor is expressed in terms of the duty being simulated.10

cable charging current: Current delivered to charge the parasitic capacitance surrounding an unloaded cable.

cable system: A system in which the supply side of the circuit breaker is connected with 100 m or more of cables or the equivalent capacitance.

circuit breaker class C0: Circuit breaker with unspecified probability of restrike when switching capacitive current under rated conditions. Syn: class C0.

circuit breaker class C1: Circuit breaker with low probability of restrike when switching capacitive current under rated conditions. Syn: class C1.

circuit breaker class C2: Circuit breaker with very low probability of restrike when switching capacitive current under rated conditions. Syn: class C2.

circuit breaker class M1: Circuit breaker with normal mechanical endurance. Syn: class M1.

7 ISO publications are available from the International Organization for Standardization (http://www.iso.org/) and the American National Standards Institute (http://www.ansi.org/). 8 NEMA publications are available from the National Electrical Manufacturers Association (http://www.nema.org/). 9 IEEE Standards Dictionary Online is available at: http://dictionary.ieee.org. An IEEE Account is required for access to the dictionary, and one can be created at no charge on the dictionary sign-in page. 10 Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this standard.


http://dictionary.ieee.org/




circuit breaker class M2: Frequently operated circuit breaker for special service requirements and designed so as to require only limited maintenance. Syn: class M2.

circuit breaker class S1: Circuit breaker with rated maximum voltage less than 100 kV intended to be used in a cable system. Syn: class S1.

circuit breaker class S2: Circuit breaker with rated maximum voltage less than 100 kV intended to be used in a line system. Syn: class S2.

close and latch: The capability of a switching device to close (allow current flow), and immediately thereafter, latch (remain closed), and conduct a specified current through the device under specified conditions.

contact position indicator: A device that is located at or near the operating mechanism to indicate whether the main contacts are in the closed or open position.

dc component (of a total current): A unidirectional (dc) component which constitutes the asymmetry of the total current. The unidirectional component can be of either polarity, but will not change polarity, and will decrease at some predetermined rate.

definite-purpose circuit breaker: A circuit breaker that has been designed, tested, and rated in accordance with general-purpose circuit breaker requirements of applicable standards and that has been designed, tested, and rated in accordance with the requirements of one or more specific performance requirements.

hydraulic system (for hydraulically operated mechanisms): An assembly of parts and devices that provides for the control of hydraulic energy for the operation of a circuit breaker or circuit breaker operating mechanism.

impulse withstand voltage: The crest value of an impulse that, under specified conditions, can be applied without causing a disruptive discharge.

initial transient recovery voltage (ITRV): A component of the transient recovery voltage that appears in the very short time immediately after current interruption. The ITRV is a result of traveling waves on the conductors adjacent to the circuit-switching device.

line-closing switching-surge maximum voltage: The maximum transient peak voltage to ground measured on a transmission line during a switching surge that results from energizing that line.

line system: A system in which the supply side of the circuit breaker is connected to overhead lines with less than 100 m of cables.

NOTE—Because the terms ‘line system’ and ‘cable system’ within this standard are only used for the selection of a class S1 or class S2 circuit breaker, a line system may be classified as a cable system regardless of the physical length of cables if the required TRV capabilities is within the capabilities of a class S1 circuit breaker.

noise (continuous): The sound level above ambient produced by vibrations, fans, and blowers.

noise (impulse): The sound level above ambient produced by a closing, opening, or combination of closing and opening operations.

noise (intermittent): The sound level above ambient produced by periodic operation (occurring one or more times per week) of such devices as compressors, hydraulic pumps, compressor unloader exhausts, air regulator valves, and air drains.

operating mechanism (of a switching device): The part of the mechanism that actuates all the main circuit contacts of the switching device either directly or by the use of pole-unit mechanisms.





pressure switch (alarm): A switch that operates on given values, or on a given rate of change to send an alarm signal when the pressure that is being monitored has reached the set point.

pressure switch (lockout): A switch that prevents the electrical operation of a circuit breaker if the operating pressure is below a predetermined value.

reclosing time (of a circuit breaker): The interval between the time when the actuating quantity of the release (trip) circuit reaches the operating value (the breaker being in the closed position) and the reestablishment of the circuit on the primary arcing contacts on the reclosing stroke.

shunt release (trip): A release energized by a source of voltage.

stroke (of a circuit breaker): The distance covered by the moving contacts between the fully closed and fully opened (at rest) positions.

symmetrical component (ac component) (of a total current): That portion of the total current that constitutes the symmetry.

total (asymmetrical) current: The combination of the symmetrical component and the dc component of the current.

transient recovery voltage (TRV): The voltage transient that occurs across the terminals of a pole of a switching device upon interruption of the current.

NOTE—TRV is the difference between transient voltages to ground occurring on the terminals. The term transient recovery voltage is usually designated as TRV, and may refer to inherent TRV, modified inherent TRV, or actual TRV as defined elsewhere. In a multipole switching device, the term is usually applied to the voltage across the first pole to interrupt. For switching devices having several interrupting units in series, the term may be applied to the voltage across units or groups of units.

3.2 Acronyms and abbreviations

ASME American Society of Mechanical Engineers AWG American wire gauge BC rated capacitor bank breaking current CC rated cable charging capacitive breaking current Cn total time of exposure at a specified sound level d peak factor, used in short-line fault TRV calculations f frequency (Hz) fbb back-to-back capacitor inrush making current frequency fi multiplying factor used in calculation of ui fr rated power frequency GIS gas-insulated substation (syn: gas-insulated switchgear) Ir rated continuous (normal) current Isc rated short-circuit current It total current Itest actual achieved current during a type test ITRV initial transient recovery voltage kaf amplitude factor, used in calculating TRV parameters kpp first-pole-to-clear factor LC rated line charging capacitive breaking current OP out-of-phase (switching conditions) OP1 first test duty for out-of-phase switching conditions type test OP2 second test duty for out-of-phase switching conditions type test PD partial discharge pu per unit





RRRV rate of rise of recovery voltage s RRRV factor, used in short-line fault TRV calculations SLF short-line fault t′ time to reach u′, used in describing TRV envelope t1 time to reach u1, used in describing TRV envelope T10 terminal fault test duty at 10% of Isc (rms) T100a terminal fault test duty at 100% of It (asymmetrical value, rms) T100s terminal fault test duty at 100% of Isc (symmetrical value, rms) t2 time to reach uc, used in describing TRV in four parameter envelope t3 time to reach uc, used in describing TRV in two parameter envelope T30 terminal fault test duty at 30% of Isc (rms) T60 terminal fault test duty at 60% of Isc (rms) td time delay of the start of the delay line used in describing TRV envelope tdL line side time delay, used in short-line fault TRV calculations ti time to ui of ITRV Ti, Tn total time of exposure permitted at a specified sound level TLF transformer limited fault tmin minimum mechanical reclose time tr reclosing time t′r second reclosing time TRV transient recovery voltage u′ reference voltage of delay line used in describing TRV envelope u1 first reference voltage used in describing TRV envelope UBD source side TRV, used in short-line fault TRV calculations uc second reference voltage used in describing TRV envelope UCD line side TRV, used in short-line fault TRV calculations UCD0 initial line side TRV, used in short-line fault TRV calculations UCDp peak line side TRV, used in short-line fault TRV calculations Ud test level for rated power-frequency withstand voltage for GIS ui reference voltage of ITRV Un line-to-neutral voltage Up test level for lightning impulse withstand voltage for GIS Ur rated maximum voltage (see also V) Us test level for phase-to-ground switching impulse withstand voltage for GIS V rated maximum voltage (see also Ur) Y permissible tripping delay Z surge impedance Zb bus surge impedance ω angular frequency (rad/s) corresponding to the frequency f

4. Service conditions

4.1 Usual service conditions

4.1.1 Indoor circuit breakers

The normal service conditions for indoor switchgear are as follows:

a) The ambient air temperature does not exceed 40 °C and its average value, measured over a period of 24 h does not exceed 35 °C.

b) The ambient air temperature does not drop below −5 °C.





c) There is no influence from solar radiation.

d) The altitude does not exceed 1000 m above sea level.

e) The ambient air is not polluted by dust, smoke, corrosive and/or flammable gases, vapors or salt and would be considered as having a site pollution severity class (SPS) “very light” according to Table C.1.

f) The conditions of humidity are as follows:

1) The average value of the relative humidity, measured over a period of 24 h, does not exceed 95%.

2) The average value of the water vapor pressure, over a period of 24 h, does not exceed 2.2 kPa.

3) The average value of the relative humidity, over a period of one month, does not exceed 90%.

4) The average value of the water vapor pressure, over a period of one month, does not exceed 1.8 kPa.

NOTE 1—Condensation can be expected where sudden temperature changes occur in periods of high humidity.

NOTE 2—High humidity may also be due to ground level rainwater or for underground applications, from incoming cable raceways connected to switchgear.

g) Vibration due to causes external to the switchgear or earth tremors do not exceed vibrations caused by operation of the switchgear itself.

4.1.2 Outdoor circuit breakers

The normal service conditions for outdoor switchgear are as follows:

a) The ambient air temperature does not exceed 40 °C and its average value, measured over a period of 24 h, does not exceed 35 °C.

b) The ambient air temperature does not drop below −30 °C.

c) Solar radiation does not exceed a level of 1044 W/m2. During periods above this intensity, the effects of solar radiation may be significant. NOTE—Details on evaluating the effects of solar radiation are in IEEE Std C37.24 [B29].

d) The altitude does not exceed 1000 m above sea level.

e) The ambient air may be polluted by dust, smoke, corrosive gas vapors, or salt. The pollution does not exceed the site pollution severity class (SPS) “light” according to Table C.1.

f) Ice coating does not exceed 20 mm.

g) The wind speed does not exceed 40 m/s (144 km/h) (90 mi/h).

h) Condensation or precipitations may occur.

i) Vibration due to causes external to the switchgear or earth tremors do not exceed vibrations caused by operation of switchgear itself.





4.2 Unusual service conditions

4.2.1 General

When high voltage switchgear is expected to be used under conditions that are different from the normal service conditions given in 4.1, the user’s requirements should refer to the information in 4.2.2 through 4.2.7. Unusual service conditions are also discussed in IEEE Std C37.010. Such conditions should be brought to the attention of those responsible for the application, manufacture, and operation of the equipment, and the guidelines for application given in IEEE Std C37.010 should be followed. Any requirements outside of the usual conditions or those conditions mentioned in IEEE Std C37.010 shall be specified by the end user.

NOTE—Appropriate action should also be taken to ensure proper operation of other components (e.g., relays, control power transformers) under such conditions.

4.2.2 Altitude

For installations at an altitude higher than 1000 m, refer to IEEE Std C37.010.

4.2.3 Exposure to pollution

For outdoor applications, ambient air that may be polluted by dust, smoke, corrosive gas, vapors, or salt at a level that exceeds “light” pollution level as defined by Annex C is considered to be a special condition.

For indoor applications, ambient air that may be polluted by dust, smoke, corrosive gas, vapors, or salt at a level that exceeds severity class (SPS) “very light” as defined by Table C.1 should be classified as “light,” “medium,” “heavy,” or “very heavy” as defined by Annex C .

NOTE—More information about exposure to pollution can be found in Annex C.

For indoor applications up to and including 52 kV, IEC/TS 62271-304 applies.

4.2.4 Temperature and humidity

For installation in a location where the ambient temperature can be outside the normal service condition range stated in 4.1.1 and 4.1.2, the ranges of minimum and maximum temperature to be specified should be as follows:

a) −50 °C to +40 °C for extremely cold climates

b) −40 °C to +40 °C for very cold climates

c) −30 °C to +40 °C for cold climates (for indoor circuit breakers, normal for outdoor)

d) −15 °C to +40 °C for moderate climates (for indoor circuit breakers)

e) −5 °C and +55 °C for very hot climates

f) −15 °C and +55 °C for hot and dry desert regions

NOTE—IEC has adopted a minimum temperature of −25 °C for normal outdoor service conditions and uses the IEEE normal service range of −30 °C to +40 °C as a special condition for cold climates.





4.2.5 Exposure to abnormal vibration, shock, or tilting

Standard switchgear is designed for mounting on substantially level structures free from excessive vibration, shock, or tilting. Where any of these standard conditions may not exist, the requirements for the particular application should be specified by the user.

For installations where earthquakes are likely to occur, the severity level according to a relevant standard or specification should be specified by the user.

NOTE—Relevant standards for seismic evaluation include: IEEE Std 693 [B21], IEEE Std C37.81 [B31], IEC 62271-300 [B17], IEC 62271-207 [B13], and IEC 62271-210 [B19].

Other unusual forms of vibration such as close proximity to mine blasting or mobile applications should be identified.

4.2.6 Wind speed

If the wind speed is expected to be in excess of the normal service wind speed, the requirements for the particular application should be specified by the user.

NOTE—Refer to IEEE Std C37.30.2 [B32] for additional information on wind loading and wind speed charts.

4.2.7 Other parameters

Any other unusual, or special environmental, operational, or other conditions prevailing at the location where switchgear is to be placed in service should be identified by the user.

NOTE—For other special environmental conditions, the user is referred to IEEE Std C37.010.

5. Descriptions of ratings and capabilities

5.1 General

The rating and capability of a circuit breaker is a designated limit of operating characteristics that is based upon usual service conditions as specified in 4.1. Preferred ratings are given in Clause 6.

The rating of a circuit breaker shall include the following parameters (as applicable):

a) Rated maximum voltage

b) Rated insulation capability

c) Rated power frequency

d) Rated continuous current

e) Rated short-circuit current

f) Rated capacitive current switching

g) Rated out of phase switching current

h) Rated standard operating duty (standard duty cycle)

i) Rated control voltage





j) Rated operating pressure for insulation and/or interruption

k) Rated operating pressure for mechanical operation

l) Rated operating endurance capabilities

m) Rated interrupting time

The establishment of a rating and the assignment of it to a circuit breaker in accordance with this standard implies performance characteristics at least equal to those set forth in the applicable subclauses of Clause 5. Compliance with these ratings is demonstrated by testing performed in accordance with IEEE Std C37.09; however, other equivalent or more effective methods of testing are not precluded. Alternatively, for designs existing prior to the adoption of this standard, the rating can be based on other tests that are judged to be equally effective on the basis of the experience gained from previous design or development tests or by service performance experience.

It shall be recognized that proper maintenance is required to ensure these ratings throughout the life of the circuit breaker.

5.2 Rated maximum voltage (V) or (Ur)

The rated maximum voltage of a circuit breaker is the highest rms phase-to-phase voltage for which the circuit breaker is designed, and is the upper limit for operation. Rated maximum voltage has the same meaning as maximum system voltage rating referred to in ANSI C84.1 [B3].

Preferred ratings are given in Clause 6.

5.3 Rated insulation capability

The rated insulation capability of a circuit breaker is its voltage withstand capability with specified magnitudes and waveshapes of voltage applied under specified conditions. Preferred ratings are given in Clause 6.

The rated insulation capability of a circuit breaker shall include the following:

a) Dry power frequency withstand voltage for indoor circuit breakers

b) Dry and wet (where applicable) power frequency withstand voltages for outdoor circuit breakers

c) Dry lightning impulse withstand voltage

d) Dry chopped wave impulse withstand voltage (where applicable)

e) Dry and wet switching impulse withstand voltage (where applicable)

In addition, the insulation of the interrupters and associated resistors or capacitors (or both) shunting the primary arcing contacts of a circuit breaker shall not be damaged when impulse voltages of specified values are applied across the interrupters and the associated shunting devices, while the primary arcing contacts are open.

5.3.1 Insulation capability of external insulation

External insulation shall conform to the performance requirements of this standard, except as follows:

Bushings shall conform to the requirements of IEEE Std C37.017.

Wet dielectric tests on bushings may not be substituted for wet dielectric tests on bushings installed on a circuit breaker.





Requirements for the rated insulation capability of the external insulation of ac high-voltage circuit breakers are given in 6.2.

5.3.2 Rated power frequency withstand voltage

5.3.2.1 Dry withstand voltage

The rated power frequency dry withstand voltage is the rms voltage that a circuit breaker in new condition shall be capable of withstanding for 1 min when tested under specified conditions (see IEEE Std C37.09).

5.3.2.2 Wet withstand voltage

The rated power frequency wet voltage withstand is the rms voltage that an outdoor circuit breaker or external components (such as supporting insulating structures) in new condition shall be capable of withstanding for 10 s when tested under specified conditions (see IEEE Std C37.09).

5.3.3 Rated lightning impulse withstand voltage

The rated lightning impulse withstand voltage is the peak value of a standard 1.2 µs × 50 µs impulse voltage wave, as defined in IEEE Std 4, that a circuit breaker in a new condition shall be capable of withstanding when tested under specified conditions (see IEEE Std C37.09).

The rated values of lightning impulse voltages for circuit breakers have the probability of flashover to ground of 10% or less. As a minimum, this is demonstrated by the test requirements of IEEE Std C37.09.

5.3.4 Lightning impulse test voltage for interrupter and resistors

Circuit breakers having a rated maximum voltage of 15.5 kV and above, having isolating gaps in series with interrupting gaps, or additional gaps in the resistor or capacitor circuits, shall be capable of withstanding a standard 1.2 µs × 50 µs lightning impulse test voltage wave when tested under specified conditions (see IEEE Std C37.09).

5.3.5 Rated chopped wave impulse withstand voltage

The rated chopped wave impulse withstand voltage is applicable to line-connected circuit breakers as shown in Table 6. The rated chopped wave impulse withstand voltage is the peak value of a standard lightning impulse voltage higher than the rated full wave impulse withstand voltage that a circuit breaker in new condition shall be capable of withstanding for a specified time, from the start of the wave at virtual time zero until flashover of a rod gap or coordinating gap occurs, when tested under specified conditions (see IEEE Std C37.09). Chopped wave impulse withstand is not a required rating for class S1 circuit breakers.

5.3.6 Rated switching-impulse withstand voltage

The rated switching-impulse withstand voltage is applicable to circuit breakers having a rated maximum voltage of 362 kV and above. The rated switching-impulse withstand voltage is the peak value of the standard 250 µs × 2500 µs switching-impulse voltage wave that a new circuit breaker shall be capable of withstanding without puncture or damage under both wet and dry conditions. This rating recognizes the circuit breaker’s ability to withstand those transient overvoltages associated with and created by the switching of open, loaded, or faulted lines and equipment.





Switching-impulse voltage surges can take many forms—unidirectional, oscillatory, or both simultaneously. At the rated switching-impulse withstand voltage the circuit breaker has the probability of external flashover to ground of 10% or less. Clause 6 lists the required values of rated switching-impulse withstand voltages for the circuit breaker open and closed positions, and it also lists the required dielectric test values for circuit breakers supplied in gas-insulated substations.

5.4 Rated power-frequency (fr)

The rated power frequency of a circuit breaker is the frequency at which it is designed to operate. Standard frequencies are 50 Hz and 60 Hz. Applications at other frequencies (e.g., 16 2/3 Hz or 25 Hz) should receive special consideration (see IEEE Std C37.010).

5.5 Rated continuous (normal) current (Ir)

The rated continuous current of a circuit breaker is the established limit of current in rms amperes at rated power frequency that it shall be required to carry continuously without exceeding any of the limitations designated in 5.5.1 and 5.5.2. For rated continuous currents, refer to the tables of preferred ratings in Clause 6.

5.5.1 Conditions of continuous current rating

The conditions on which continuous current ratings are based are as follows:

a) Circuit breakers are used under the usual service conditions defined in 4.1.

b) Current ratings shall be based on the total temperature limits of the materials used for circuit breaker parts. A temperature rise reference is given to permit testing at reduced ambient.

c) Circuit breakers designed for installation in enclosures shall meet these ratings when in their proper enclosure and based on a 40 °C ambient temperature outside the enclosure.

d) Outdoor circuit breakers and class S1 circuit breakers not intended for use in enclosures shall be rated based on a 40 °C ambient temperature.

A circuit breaker is considered to be capable of being loaded above its continuous current rating as limited by IEEE Std C37.010 depending upon circuit breaker pre-loading, duration of the load, ambient temperature and the value of the thermal time constant determined from circuit breaker continuous current design tests.

5.5.2 Temperature limits on insulating materials, connections and surfaces

Table 1 provides limitations on the maximum permitted total temperature (with rise above normal ambient condition of 40 °C provided for convenience) for circuit breakers.





Table 1 —Limits of temperature and temperature rise

Nature of the part and material a, b, c Total

temperature (°C)

Temperature rise above

ambient (°C) 1. Material used as insulation

and metal parts in contact with insulation of these classes d

O 90 50 A 105 65 B 130 90 F 155 115 H 180 140 C 220 180 Oil e 90 50

2. Contacts f Bare copper and bare-copper alloy — in reactive gases(RG) g 75 35 — in non-reactive gases(NRG) g 105 65 — in oil 80 40

Silver-coated or nickel-coated h — in reactive gases(RG) g 105 65 — in non-reactive gases(NRG) g 105 65 — in oil 90 50

Tin-coated h — in reactive gases(RG) g 90 50 — in non-reactive gases(NRG) g 90 50 — in oil 90 50

3. Connections, bolted or the equivalent i

Bare-copper, bare-copper alloy, bare aluminum or bare-aluminum alloy

— in reactive gases(RG) g 90 50 — in non-reactive gases(NRG) g 115 75 — in oil 100 60

Silver-coated or nickel-coated — in reactive gases(RG) g 115 75 — in non-reactive gases(NRG) g 115 75 — in oil 100 60

Tin-coated — in reactive gases(RG) g 105 65 — in non-reactive gases(NRG) g 105 65 — in oil 100 60

4. All other contacts or connections made of bare metals or coated with other materials

Footnote j Footnote j

5. Terminals for the connection to external conductors by screws or bolts k

Bare-conductor 90 50 Silver-coated, nickel-coated, tin-coated 105 65 Other coatings Footnote j Footnote j

6. Metal parts acting as springs Footnote l Footnote l 7. Accessible surfaces External surfaces handled by the operator in

the normal course of his or her duties 50 10

External surfaces accessible by the operator in the normal course of his or her duties

70 30

External surfaces not accessible to an operator in the normal course of his or her duties

110 70

Table continues





Table 1—Limits of temperature and temperature rise (continued) a According to its function, the same part may belong to several categories as listed Table 1. In this case, the

permissible maximum values of total temperature and temperature rise to be considered are the lowest among the relevant categories.

b For sealed interrupters, the values of total temperature and temperature-rise limits are not applicable for parts inside the sealed interrupter. The remaining parts shall not exceed the values of temperature and temperature rise given in Table 1.

c The temperatures of conductors between contacts and connections are not covered in Table 1, as long as the temperature at the point of contact between conductors and insulation does not exceed the limits established for the insulating material.

d The classes of insulating materials are those given in IEEE Std 1. e The top oil (upper layer) temperature shall not exceed 40 °C rise or 80 °C total. The 50 °C and 90 °C values refer

to the hottest spot temperature of parts in contact with oil. f When contact parts have different coatings, the permissible temperatures and temperature rises shall be those of the

part having the lower value permitted in Table 1. g NRG, (-Non-Reactive Gases), for the purposes of this standard, are considered as not accelerating ageing of

contacts by corrosion or oxidation due to their chemical characteristics and demonstrated operational records. — Recognized NRG are SF6, N2, CO2, and CF4. They can be used pure or as a mixture of various NRG. — RG, (Reactive Gases), for the purposes of this standard, are reactive gases that can accelerate ageing of

contacts either by corrosion phenomena (presence of humidity) or by oxidation phenomena (mostly due to ambient air medium like oxygen). Gases classified as RG are ambient air, “dry” air, any gas not classified as NRG and any mixture that includes an RG.

NOTE—Some gases considered as RG in the classification above may be re-classified as NRG, taking advantage of service experience or demonstration justifying the change of classification.

— For description of these corrosion and oxidation phenomena, refer to IEC 60943 [B16]. — Due to the absence of corrosion and oxidation, a harmonization of the limits of temperature for different

contact and connection parts in the case of gas insulated switchgear appears appropriate. The permissible temperature limits for bare copper and bare copper alloy parts can be equalized to the values for silver coated or nickel-coated parts in the case of NRG atmospheres.

— In the particular case of tin-coated parts, due to fretting corrosion effects (refer to IEC 60943 [B16]) an increase of the permissible temperatures is not applicable, even under the oxygen-free conditions of SF6. Therefore, the initial values for tin-coated parts are retained.

h The quality of the coated contacts shall be such that a layer of coating material remains at the contact area a) After making and breaking tests (if any). b) After short-time withstand current tests. c) After the mechanical endurance test; according to the relevant specifications for each piece of equipment.

Otherwise, the contacts shall be regarded as “bare.” i Where the connection parts have different coatings, the permissible temperature rise shall be as follows:

— For factory-controlled inaccessible connections (e.g., not subject to servicing in the field) and with both sides having copper as the base metal, those of the surface material having the highest value permitted in item 3 of Table 1.

— For all other connections, those of the surface material having the lowest value permitted in item 3 of Table 1.

j When materials other than those given in Table 1 are used, their properties shall be considered in order to determine the maximum permissible temperature rises.

k The values of temperature and temperature rise are valid even if the conductor to the terminals is bare. l The temperature shall not reach a value where the temper of the material is impaired.





5.6 Rated short-circuit current and related required capabilities

The short-circuit current rating of a circuit breaker is the symmetrical component of short-circuit current in rms amperes (see 5.6.1) to which all required short-circuit capabilities are referenced. All values apply to both grounded and ungrounded short-circuits on predominantly inductive three-phase loads of low power factor, with rated power frequency and phase-to-phase recovery voltage equal to the rated maximum voltage.

5.6.1 Rated short-circuit current (Isc)

The rated short-circuit current of a circuit breaker is the highest value of the symmetrical component of the three-phase, short-circuit current in rms amperes measured from the envelope of the current wave at the instant of primary arcing contact separation that the circuit breaker shall be required to interrupt at rated maximum voltage and on the standard operating duty. It also establishes, by fixed ratios as defined in 5.6.2.3, the highest currents that the circuit breaker shall be required to close and latch against, to carry, and to interrupt. Preferred values of rated short-circuit current follow the R10 series, see tables in Clause 6.

5.6.2 Required related capabilities

The circuit breaker shall have the required related capabilities described in 5.6.2.1 through 5.6.2.6.

5.6.2.1 Required symmetrical interrupting capability for three-phase faults

For three-phase faults, the required symmetrical interrupting capability of a circuit breaker is the value of the symmetrical component of the short-circuit current in rms amperes at the instant of arcing contact separation that the circuit breaker shall be required to interrupt at a specified operating voltage, on the standard operating duty cycle, and with a direct current component of less than 20% of the current peak value of the symmetrical component.

5.6.2.2 Required asymmetrical interrupting capability for three-phase faults

The required asymmetrical current interrupting capability of a circuit breaker is the value of the total rms short-circuit current (It) at the instant of the arcing contact separation that the circuit breaker shall be required to interrupt at a specified operating voltage and on the standard operating duty cycle.

The required percent value of the dc component is based on a standard time constant of 45 ms (corresponding to X/R values of 17 and 14 for 60 Hz and 50 Hz, respectively) and an assumed release delay, or relay time of 1/2 cycle, as illustrated in Figure 1. The elapsed time shown in Figure 1 is the contact parting time and is equal to the sum of 1/2 cycle of relay time (on the basis of the applicable rated power frequency) plus the minimum opening time of the circuit breaker.





Figure 1—Percent dc component of asymmetric current

as a function of contact parting time The required asymmetrical current interrupting capability shall be determined from the rated value of the symmetrical current and the direct current component of the current, expressed as a percentage of the peak value of the symmetrical current, Isc, in accordance with Equation (1):

2

t sc%1 2100

dcI I

(1)

For time constants greater than 45 ms, see IEEE Std C37.09 and IEEE Std C37.010.

The peak current and duration of the last half wave prior to interruption during asymmetrical testing shall be recorded. This will be used for checking asymmetrical capability for specific applications where the time constant and/or relay time are different from the standard values of 45 ms time constant and 0.5 cycle (8.33 ms at 60 Hz) or (10 ms at 50 Hz) relay time.

5.6.2.3 Rated closing, latching, and short-time current carrying capability

The circuit breaker shall be capable of the following:

a) Closing and latching any power frequency making current whose maximum peak (peak making current) is:

1) Equal to or less than 2.6 times the rated short circuit current for 60 Hz power rated frequency and having time constants less than or equal to 45 ms

2) Equal to or less than 2.5 times the rated short circuit current for 50 Hz power rated frequency and having time constants less than or equal to 45 ms





3) Equal to or less than 2.7 times the rated short circuit current for all time constants greater than 45 ms up to 133 ms

b) Carrying a short-circuit current (short-time current), Isc, for a period of time as specified in Clause 6 under the list of preferred ratings. These time durations establish the maximum permissible tripping time delay, Y, for each circuit breaker group.

5.6.2.4 Required reclosing capability

Factors for reducing the rated interrupting capacity for reclosing duty cycles other than the standard operating duty can be determined, when required, using the method contained in IEEE Std C37.010.

5.6.2.5 Service capability duty requirements

The circuit breaker shall be capable of interrupting a number of terminal faults where the sum of the symmetrical test currents is equivalent to the service capability duty of at least:

a) 8 × the rated short-circuit breaking current (Isc), for circuit breakers rated below 72.5 kV

b) 6 × Isc for circuit breakers rated 72.5 kV and above

5.6.2.6 Electrical endurance capability

The electrical endurance of a circuit breaker is the capability to repeatedly switch currents significantly less than the rated short circuit current, Isc. Experience has shown that for modern circuit breaker designs, basic electrical endurance capability is covered by meeting the required service capability of 5.6.2.5. Where extended electrical endurance is required, Table F.1 provides the requirements for class E2 circuit breakers intended for auto-reclosing duty (normally class S2, rated 72.5 kV and lower). An example of such extended duty is a class S2 circuit breaker intended for auto-reclosing that may be exposed to a significant number of low-level faults on connected overhead lines. This category is intended for qualifying circuit breakers for extended electrical duty beyond the requirements of a) and b) in 5.6.2.1. While the E2 exceeds the accumulative current requirements of a) and b), it does not replace the requirements of a) and b) in 5.6.2.1, which are a portion of the required type tests. Circuit breakers not requiring electrical endurance capability class E2 are classified class E1, termed basic electrical endurance.

NOTE—The requirements for basic electrical endurance (class E1) and class E2 for circuit breakers without auto-reclosing duty as defined in IEC 62271-100 are different than those described in this clause. Meeting the requirements of IEC 62271-100 can, but will not necessarily, meet the requirements for basic electrical endurance defined in this clause.

5.6.2.6.1 Circuit breakers rated below 72.5kV

The sum of the currents is a minimum of 8 times the rated short circuit current of the circuit breakers.

Each T100s and T100a operation shall be included as 1 × Isc in the accumulation. The degradation of the interrupter for each breaking test is considered to be a power function of the current. The power function is the ratio of the test current Itest to Isc, raised to the power of 1.8. The contribution of each current interruption to the service capability shall be determined as follows:

If Itest is less than Isc, the contribution is [(Itest) / (Isc)] 1.8 × Isc.

If Itest is equal to or greater than Isc, the contribution is Isc.

Each T60 operation, performed at 0.6 × Isc, shall be included in the accumulation as 0.4 × Isc, but no more than (5) T60 tests may be included in the accumulation.





Contributions of breaking test currents less than 0.6 × Isc shall not be included in the accumulation.

At a minimum, one T100s or T100a shall be included in the Isc test accumulation.

5.6.2.6.2 Circuit breakers rated 72.5kV and higher

The service capability is demonstrated by performing terminal fault test duties T60 and T100s and/or T100a on the same pole in the case of single-phase tests or the same circuit breaker in the case of three-phase tests. Alternatively, it is possible to perform T100s with six interruptions at 100% rated short-circuit current in order to have an accumulation of 6 times rated symmetrical interrupting capability.

At a minimum, one T100s or T100a shall be included in the Isc test accumulation.

5.7 Transient recovery voltage (TRV)

5.7.1 General

The TRV related to the rated short-circuit interrupting current in accordance with 0 is the reference voltage that constitutes the limit of the prospective TRV of circuits, which the circuit breaker shall be capable of withstanding under fault conditions. Each TRV rating is defined for a three-phase circuit breaker. Refer to the tables of preferred ratings for prospective TRV in Clause 6.

See Annex B for more detailed information on TRV and application considerations.

5.7.2 Summary of rated TRV parameters

5.7.2.1 Table of rated TRV parameters

Table 2 summarizes rated TRV parameters. The parameters in Column 1 are illustrated in Figure 2 and Figure 3. The derivation of these values is further described in IEEE Std C37.011 [B26].

Table 2 —Rated TRV parameters Rated voltages and system conditions

TRV parameter

100 kV and above kpp = 1.3

100 kV and above kpp = 1.5

Below 100 kV line systems

kpp = 1.5 (class S2)

Below 100 kV cable systems

kpp = 1.5 (class S1) Col. 1 Col. 2 Col. 3 Col. 4 Col. 5

Four-parameter (Figure 2)

Four-parameter (Figure 2)

Two-parameter (Figure 3)

Two-parameter (Figure 3)

kaf 1.4 1.4 1.54 1.4 u1 0.796 × Ur 0.919 × Ur — — t1 u1/RRRV u1/RRRV — —

u1/ t1 2 kV/us 2 kV/us — — uc 1.49 × Ur 1.72 × Ur 1.88 × Ur 1.715 × Ur

t2 or t3 t2 = 4 t1 t2 = 4 t1 t3 a t3 b td 2 μs 2 μs td = 0.05 t3 td = 0.15 t3 u′ u1/2 u1/2 uc/3 uc/3 t′ td + u′/RRRV td + u′/RRRV td + u′/RRRV td + u′/RRRV

a For line systems, time t3 for terminal fault and short-line fault is equal to 4.65 × (Ur)0.7 with t3 in microseconds and Ur in kilovolts. The equation is derived from the values given in Table 6 of IEEE Std C37.06-2009 [B24] for rated voltages 15.5 kV, 25.8 kV, 48.3 kV, and 72.5 kV.

b For cable systems, the values of t3 are those found in Table 10.





Figure 2—Four-parameter TRV envelope

Figure 3—Two-parameter TRV envelope

5.7.2.2 Standard values of TRV related to the rated short-circuit interrupting current

Standard values of required TRV capabilities for three-pole circuit breakers of rated voltages below 100 kV make use of two parameters.

Standard values of required TRV capabilities for three-pole circuit breakers of rated voltages 100 kV and above make use of four parameters.

The TRV tables also indicate values of rate of rise, taken as uc/t3 and u1/t1, in the two-parameter and in the four-parameter cases, respectively, which together with TRV peak values uc may be used for purposes of specification of TRV.

The values given in the tables are prospective values. They apply to circuit breakers for general transmission and distribution in three-phase systems having service frequencies of 50 Hz or 60 Hz and consisting of transformers, overhead lines, and short lengths of cable.





In the case of single-phase systems or where circuit breakers are for use in an installation having more severe conditions, the values may be different, particularly for the following cases:

a) Circuit breakers adjacent to generator circuits

b) Circuit breakers directly connected to transformers without appreciable additional capacitance between the circuit breaker and the transformer, which provides approximately 50% or more of the rated short-circuit interrupting current of the circuit breaker

c) Circuit breakers in substations with series reactors

d) Circuit breakers used for series compensated lines

e) Circuit breakers in substations with capacitor banks

The TRV corresponding to the rated short-circuit interrupting current when a terminal fault occurs is used for testing at short-circuit interrupting currents equal to the rated value. However, for testing at short-circuit interrupting currents less than 100% of the rated values, other values of TRV are specified (see 5.7.2.3.1). Further additional requirements apply to circuit breakers rated at 15.5 kV and above and having rated short-circuit interrupting currents exceeding 12.5 kA, which may be connected to overhead lines and may be subjected to short-line fault conditions (see 5.7.2.3.3).

5.7.2.3 Related required transient voltage withstand capabilities

5.7.2.3.1 Fault currents other than rated

The circuit breaker shall be capable of interrupting short-circuit currents that are less than the rated short- circuit current. This requires withstanding a TRV envelope where the uc value is higher and the t2 or t3 time is shorter resulting in a faster RRRV than the values corresponding to the rated short-circuit current.

The related TRV envelopes are defined by the use of multiplier factors shown in Table 3 times the rated values and the resulting values are shown in Table 9, Table 10, Table 13, Table 14, Table 17, Table 18, Table 19, or Table 20 as appropriate. That is, the related required peak voltage at a lower short-circuit current is a multiplier times the two- and four-parameter values specified at the rated short-circuit current. The related required time to reach the peak voltage is a multiplier times the two- and four-parameter values specified at the rated short-circuit current. Note that as the current is decreased, the multipliers have the effect of increasing the peak TRV value and of increasing the RRRV.

Table 3 shows the family of amplitude factors and rates-of-rise or t3 values for the various test duties.

The effect of these multipliers on the TRVs at the various specified fractional values of the rated short-circuit current are illustrated as families of TRV envelopes as shown in the following four figures:

Figure 4 illustrates a family of TRVs for circuit breakers rated 100 kV and above.

Figure 5 compares the TRVs with kpp = 1.5 to those with kpp = 1.3 for circuit breakers rated 100 kV and above at 10% and 100% of the rated short-circuit current.

Figure 6 illustrates a family of TRVs for circuit breakers rated below 100 kV.

Figure 7 compares the TRVs for cable-connected systems (class S1) to those for line-connected systems (class S2) for circuit breakers rated below 100 kV at 10% and 100% of the rated short-circuit current.

The TRV curves in Figure 4, Figure 5, Figure 6, and Figure 7 on a per unit basis using uc at T100 as 1.0 per unit of voltage and t2 or t3 at T100 as 1.0 per unit of time for each family.





More discussion of the TRV multiplier background is found in Annex B.

Table 3 —Related required TRV parameters

TRV parameter a

100 kV and above kpp = 1.3 b

100 kV and above kpp = 1.5 c

Below 100 kV kpp = 1.5 line systems (class S2)d

Below 100 kV kpp = 1.5 cable systems (class S1)e

Col. 1 Col. 2 Col. 3 Col. 4 Col. 5

kaf at T100 1.4 1.4 1.54 1.4 kaf at T60 1.5 1.5 1.65 1.5 kaf at T30 1.58 1.58 1.74 1.6 kaf at T10 1.76 1.64 1.80 1.7 kaf at OP 1.25 1.25 1.25 1.25 u1 at T60 1.0 × u1 at T100 1.0 × u1 at T100 RRRV at T100 2 kV/µs 2 kV/µs t3 at T100 = 1 pu t3 at T100 = 1 pu RRRV at T60 3 kV/µs 3 kV/µs t3 at T60 = 0.67 pu t3 at T60 = 0.44 pu RRRV at T30 5 kV/µs 5 kV/µs t3 at T30 = 0.4 pu t3 at T30 = 0.22 pu RRRV at T10 7 kV/µs 7 kV/µs t3 at T10 = 0.4 pu t3 at T10 = 0.22 pu RRRV at OP 1.54 kV/µs 1.67 kV/µs t3 at OP = 2.0 pu t3 at OP = 2.0 pu t2 at T100 t2 at T100 = 1 pu t2 at T100 = 1 pu t2 at T60 t2 at T60 = 0.5 pu t2 at T60 = 0.5 pu

t3 at T30 uc(T30)/RRRV(T30) [t3 at T30 = 0.211 pu]

uc(T30)/RRRV(T30) [t3 at T30 = 0.211 pu]

t3 at T10 uc(T10)/RRRV(T10) [t3 at T10 = 0.168 pu]

uc(T10)/RRRV(T10) [t3 at T10 = 0.156 pu]

t2 at OP t2 at OP = 2.0 pu t2 at OP = 2.0 pu a For circuit breakers rated 100 kV and above, the kaf values in Columns 2 and 3 are derived from kaf = 1.4 at T100 and

the E2 multipliers from Table 6, Column 5 in IEEE Std C37.06-2009 [B24] with the exception of kaf at T10 = 1.76 for kpp = 1.3. This higher kaf value is derived as 1.76 = 1.7 × 0.9 × 1.5/1.3 where 1.7 is the typical amplitude factor for transformers and 0.9 is the typical fraction of system voltage across the transformer and 1.5/1.3 recognizes that transformers are often ungrounded. Note that 1.76 is also 1.26 × 1.4, making 1.26 the kaf multiplier at T10 for kpp = 1.3 for breakers rated below 100 kV.

b For line systems (class S2), kaf values are derived from kaf =1.54 at T100 and E2 multipliers from this standard and t3 multipliers are also from IEEE Std C37.06-2009 [B24].

c For cable systems (class S1), kaf values are derived from kaf =1.4 at T100 and peak multipliers and t3 multipliers derived from IEC 62271-100.

d For circuit breakers rated 100 kV and above, t3 values at T30 and T10 are determined primarily from the peak TRV and the RRRV. An equivalent t3 multiplier is derived. e.g., t3 at T30 = uc(T30)/ RRRV(T30) is equivalent to t3 at T30 = 0.211 × t2 at T100.

e The factor k (t3 at T30) = 0.211 is also determined by (kaf at T30) × 2 / (5 × 3). This is in contrast to previous methods where t3 at T30 was determined by a multiplier times t2 at T100 and the RRRV was then derived.





Figure 4—A family of four-parameter and two-parameter TRV envelopes

typical of TRVs for ratings 100 kV and above for kpp = 1.3

Figure 5—A comparison of four-parameter and two-parameter

TRV envelopes typical of TRVs for ratings 100 kV and above for kpp = 1.5 versus kpp = 1.3 at T100 and T10





Figure 6—A family of two-parameter TRV envelopes typical of TRVs

for ratings below 100 kV for line systems

Figure 7—A comparison of two-parameter TRV envelopes typical of

TRVs for ratings below 100 kV for line versus cable systems at T100 and T10

5.7.2.3.2 Definite purpose ratings for transformer limited faults (TLF)

Certain applications have been identified where the TRVs have very fast rise times. These applications often occur in locations next to large transformers that produce transient oscillations at very high natural frequencies. Following reports of circuit breaker failures in applications where very fast TRVs were determined to be the cause, and after thorough analysis of TRV data gathered from all parts of the world, these special applications are covered in recommended practice IEEE Std C37.06.1 [B25].





5.7.2.3.3 Short-Line Fault (SLF)

Circuit breakers directly connected to overhead lines having rated voltages of 15.5 kV and above and with rated short-circuit currents above 12.5 kA shall be capable of interrupting single-phase short-line faults at any distance from the circuit breaker, on a system where the following conditions apply:

a) The TRV on a terminal fault is within the TRV envelope.

b) The voltage in the first ramp of the sawtooth wave is equal to or less than that in an ideal system where the parameters of the surge impedance Z and the peak factor d listed in Table 4 are applied.

c) There is a line-side time delay with the values listed in Table 4.

d) An RRRV factor to account for the difference in the di/dt at 50 Hz and 60 Hz.

e) Single-phase to ground short-line faults shall be able to be cleared with any source-side available short-circuit current up to the rated value.

Table 4 —Short-line fault standard values b

Ur (kV)

Number of conductors per phase

Z (Ω′) d s

[(kV/µs)/kA]a tdL

(µs) 15.5 ≤ Ur ≤ 38 1 450 1.6 0.200 0.240 0.1 >38 ≤ Ur ≤ 170 1 to 4 450 1.6 0.200 0.240 0.2

Ur > 170 1 to 4 450 1.6 0.200 0.240 0.5 a The RRRV factor s is a value in (kV/µs)/kA. b These values cover the short-line faults dealt with in this standard. For very short lines where tL < 5tdL, not all

requirements as given in the table can be met. The procedures for approaching very short lines are given, IEC/TR 62271-306 Guide for Application of IEC 62271-100 and IEC 62271-1 [B16].

The TRV for this short-line fault is illustrated in Figure 8. The voltage across the breaker is the difference between the source-side transient described as a four-parameter TRV with a time delay and a line-side sawtooth transient. Short-line fault terminology is described graphically in Figure 9.

Figure 8—Short-line fault (SLF) TRV waveform





Figure 9—Short-line fault equivalent circuit and terminology

5.7.2.3.4 Initial transient recovery voltage (ITRV)

Circuit breakers rated 100 kV and above with rated short-circuit currents of 31.5 kA and above shall have an ITRV capability for phase-to-ground faults as defined by the envelope shown in Figure 10. Three-phase ITRV is not covered by this standard.

Figure 10—Initial transient recovery voltage

The ITRV envelope rises linearly from the origin to the first peak voltage ui at time ti (see Figure 10). The first peak voltage and the time to the first peak voltage are determined by the fault current, bus surge impedance, bus wave velocity, and the distance from the circuit breaker to the first major discontinuity of bus surge impedance.

As an example, the first major discontinuity of bus surge impedance may be a lumped capacitance of 1000 pF or more connected to the bus or a reduction of the bus surge impedance (i.e., the interconnection of two or more buses or lines). The apparent wave velocity is approximately 300 m/µs for outdoor substations.





The times to first peak voltage ti for phase-to-ground faults are given in Table 5.

The first peak voltage ui is as follows in Equation (2):

1/2 –6i b i 2 10 kVu I Z tω (2)

where

bZ is the bus surge impedance, and is 260 Ω (outdoor substations, phase-to-ground faults only) or 325 Ω at 800 kV

it is in microseconds I is in kiloamperes ω = 2πƒ

For circuit breakers installed in gas-insulated substations, the ITRV can be neglected because of low bus surge impedance and small distances to the first major discontinuity.

Table 5 —Initial TRV values, rated voltages ≥ 100 kV

Rated voltage Multiplying factor to determine ui as function of the rms value of the short-circuit interrupting current

Isc a b c

Time to first peak voltage

Ur fi ti kV kV / kA μs

50 Hz 60 Hz 100 0.046 0.056 0.4 123 0.046 0.056 0.4 145 0.046 0.056 0.4 170 0.058 0.070 0.5 245 0.069 0.084 0.6 300 0.08 1 0.098 0.7 362 0.092 0.112 0.8 420 0.092 0.112 0.8 550 0.116 0.139 1.0 800 0.159 0.191 1.1

a The actual initial peak voltages are obtained by multiplying the values in these columns by the rms value of the short-circuit interrupting current.

b These values cover both three-phase and single-phase faults and are based on the assumption that the busbar, including the elements connected to it (supports, current and voltage transformers, disconnectors, etc.) can be roughly represented by a resulting surge impedance Zb of about 260 Ω in the case of a rated voltage lower than 800 kV and by a resulting surge impedance Zb of about 325 Ω in the case of a rated voltage of 800 kV. The relation between fi and ti is then:

fi = ti × Zb × ω × (2) 0.5 c Where ω = 2 × π × f is the angular frequency corresponding to the rated frequency of the circuit breaker.

5.8 Rated capacitive current switching

Capacitive switching currents may comprise part or all of the operating duty of a circuit breaker such as the charging current of an unloaded transmission line or cable or the load current of a shunt capacitor bank.

Three classes of circuit breakers are defined according to their restrike performances:

a) Class C0 unspecified probability of restrike during capacitive current breaking; up to one restrike per operation

b) Class C1: low probability of restrike during capacitive current breaking





c) Class C2: very low probability of restrike during capacitive current breaking

The rating of a circuit breaker for capacitive current switching shall include, where applicable:

Rated line-charging breaking current applicable to all class S2 circuit breakers

Rated cable-charging breaking current; applicable to all class S1 circuit breakers

Rated single capacitor bank breaking current

Rated back-to-back capacitor bank breaking current (only for class C1 or class C2)

Rated back-to-back capacitor bank inrush making current

Preferred values of rated capacitive switching currents are given in Clause 6.

The recovery voltage related to capacitive current switching depends on the following:

The grounding of the system

The grounding of the capacitive load, for example shielded cable, capacitor bank, transmission line

The mutual influence of adjacent phases of the capacitive load, for example belted cables, open air lines

The mutual influence of adjacent systems of overhead lines on the same route

The presence of single or two-phase ground faults

Each capacitive current switching rating assigned (a, b, c, above) must have an associated class (C0, C1, or C2) with it.

The probability of restrike is related to the performance during the series of type tests stated in IEEE Std C37.09.

A circuit breaker can be of class C2 for one kind of application (for example in grounded neutral systems) and of class C1 for another kind of application where the recovery voltage stress is more severe (for example in systems other than grounded neutral systems).

Circuit breakers with a restrike probability other than that of class C0, C1, or class C2 are not covered by this standard. The terminology of restrike free circuit breakers is no longer recognized by IEEE or IEC standards.

5.8.1 Rated line-charging capacitive breaking current (LC)

The rated line-charging breaking current is the maximum line-charging current that the circuit breaker shall be capable of breaking at its rated voltage under the conditions of use and behavior prescribed in this standard. The specification of a rated line-charging breaking current is mandatory for all class S2 circuit breakers.

5.8.2 Rated cable-charging capacitive breaking current (CC)

The rated cable-charging breaking current is the maximum cable-charging current that the circuit breaker shall be capable of breaking at its rated voltage under the conditions of use and behavior prescribed in this standard. The specification of a rated cable-charging breaking current is mandatory for all class S1 circuit breakers.





5.8.3 Rated capacitor bank breaking current (BC)

The rated capacitor bank breaking current is the capacitive current that the circuit breaker shall be capable of breaking at its rated voltage while maintaining its rated probability of restrike performance. This breaking current is independent of single-bank or back-to-back application of the circuit breaker.

NOTE—Back-to-back applications typically result in higher inrush making currents which may influence the size of the capacitor bank, and thus the capacitive current that may be switched under single-bank or back-to-back applications.

5.8.4 Rated back-to-back capacitor bank transient peak inrush making current (Ibb)

The rated back-to-back capacitor bank transient peak inrush making current is the peak value of the current that the circuit breaker shall be capable of making at its rated voltage and with a frequency of the inrush current (see 5.8.5) appropriate to the service conditions. Refer to IEEE Std C37.012 [B27] for discussion of the limitations on Ibb magnitude.

5.8.5 Back-to-back capacitor bank inrush current making frequency (fbb)

The back-to-back capacitor bank inrush making frequency, fbb, is the frequency of the inrush current Ibb to which the breaker was tested (see 5.8.4). Either the prospective value of fbb based upon the test circuit or in the case where the test object significantly modifies the actual frequency of the inrush current, the median value of the recorded inrush current frequencies may be declared as fbb. In service there is no practical upper limit for fbb. The inrush (or outrush) current frequency is important for shock wave limited devices such as oil circuit breakers but has only a small influence on other breaking technologies. The preferred values for the inrush current frequency given in Table 15 and Table 21 are intended to allow for common test arrangements that resemble user experiences. Ibb is the limiting quantity and its primary effect is contact wear for SF6 technologies and restrike performance for vacuum technologies. The previously used I × f limitations were only valid for oil breakers and are not important for vacuum or SF6 technologies. Ibb is based on a 2000 operation service life with no contact maintenance. For fewer operations, Ibb can be much higher up to the close and latch capability for at least two operations.

5.9 Assigned out-of-phase switching current rating

Assigned rated out-of-phase switching is optional for all circuit breakers.

This rating applies to circuit breakers intended to be used for switching the connection between two parts of a three-phase system during out-of-phase conditions. Out-of-phase is an abnormal circuit condition of loss or lack of synchronism between parts of an electrical system on either side of a circuit breaker. The phase angle between rotating vectors representing the voltages on either side of the circuit breaker at the instant of its operation may differ by as much as full-phase opposition.

5.9.1 Assigned out-of-phase switching current rating

The assigned out-of-phase switching current rating is the maximum out-of-phase current that the circuit breaker shall be capable of switching at a rated power frequency out-of-phase recovery voltage equal to 2 times the rated maximum voltage divided by 3 for grounded systems, and 2.5 times the rated maximum voltage divided by 3 for ungrounded systems (see IEEE Std C37.09). If a circuit breaker has an assigned out-of-phase switching current rating, the preferred rating shall be 25% of the Isc (symmetrical) short-circuit current expressed in kiloamperes, unless otherwise specified.





5.9.2 Interrupting time for out-of-phase switching

The interrupting time for out-of-phase switching is permitted to exceed the rated interrupting time by

a) 50% for circuit breakers with rated interrupting times over 50 ms

b) One cycle for circuit breakers with rated interrupting times of 50 ms or less

5.10 Rated standard operating duty (standard duty cycle)

The standard operating duty of a circuit breaker is as follows:

O – tr – CO – t′r – CO

where

O = Open CO = Close-Open tr = 15 s for circuit breakers not rated for rapid reclosing and = 0.3 s for circuit breakers rated for rapid reclosing duty t′r = 3 min

Tests performed with a duty cycle of O – tr – CO – 15 s – CO satisfactorily demonstrates the rated standard operating cycle of O – tr – CO – 3 m – CO.

5.10.1 Rated Interrupting time

The rated interrupting time is based on a three phase symmetrical short circuit current. It is the maximum interval between the energizing of the open release device at rated control voltage and operating pressure(s), and the interruption of the current in the main circuit in all poles. Actual interrupting time of a single phase fault and/or an asymmetrical fault may be longer than the rated interrupting time. See IEEE Std C37.010 for guidance on calculating these values.

For rated out-of-phase switching, based on single phase testing, the rated interrupting time is the interrupting time plus 0.75 × 1/2 cycle.

5.10.2 Rated minimum reclosing time

The minimum reclosing time of a circuit breaker is the shortest permissible time in which the circuit breaker is required to reclose with rated control voltage and rated pressure. It may be necessary to add an external time delay to meet specific application requirements (see IEEE Std C37.010). Rated reclosing times are given in Clause 6. It may also be necessary to add a time delay relay in the breaker control circuit to prevent reclosing faster than the time defined in the standard duty cycle or as required for proper functioning of the circuit breaker itself.

5.10.3 Contact parting time

The contact parting time shall be considered equal to the sum of 1/2 cycle (practical minimum relay time) plus the minimum opening time of the circuit breaker specified by the manufacturer (see IEEE Std C37.010).

NOTE—This definition is not the same as definition of contact parting time used in IEEE Std 551.





5.11 Rated control voltage

The rated control voltage of a circuit breaker is the designated voltage measured at the point of user connection to the circuit breaker, including, if necessary, accessories supplied or required by the manufacturer to be installed in series with it. The transient voltage in the entire control circuit, due to interruption of the control current, shall be limited to 1500 V, peak.

5.12 Rated operating pressure for insulation and/or interruption

Rated filling levels for insulation and/or operation, refers to the pressure in Pa (or density) or liquid mass assigned by the manufacturer referred to atmospheric air conditions of 20 °C and 101.3 kPa (absolute) at which the gas- or liquid-filled switchgear is filled before being put into service.

5.12.1 Alarm pressure for insulation and/or interruption

The pressure in pascals, for insulation and/or operation, refers to the standard atmospheric air conditions of +20 °C and 101.3 kPa (absolute) (or density), which may be expressed in relative or absolute terms, at which a monitoring signal may be provided to indicate that replenishment is necessary.

5.12.2 Minimum operating pressure for insulation and/or interruption

The pressure in pascals, for insulation and/or operation, refers to the standard atmospheric air conditions of +20 °C and 101.3 kPa (absolute) (or density), which may be expressed in relative or absolute terms, which represents the lower limit below which the circuit breaker rated performance and capabilities are no longer available and where the circuit breaker is locked out.

5.13 Rated operating pressure for mechanical operation and special capabilities

The pressure, in pascals, refers to the standard atmospheric air conditions of +20 °C and 101.3 kPa (absolute) (or density), which may be expressed in relative or absolute terms, to which the control device (operating mechanism) is filled before being put into service or automatically replenished.

5.13.1 Alarm pressure for mechanical operation

The pressure in pascals refers to the standard atmospheric air conditions of +20 °C and 101.3 kPa (absolute) (or density), which may be expressed in relative or absolute terms, at which a monitoring signal may be provided to indicate that pressure replenishment for the control device (operating mechanism) is necessary.

5.13.2 Minimum operating pressure for mechanical operation

The pressure in pascals refers to the standard atmospheric air conditions of +20 °C and 101.3 kPa (absolute) (or density), which may be expressed in relative or absolute terms, which represents the lower limit of pressure for proper operation of the control device (operating mechanism).

5.13.3 Required mechanical operating endurance capabilities

The required mechanical operating endurance capabilities are the types and numbers of complete closing-opening operations that the circuit breaker shall be capable of performing. The schedule of operating endurance capabilities for circuit breakers is given in Clause 6. When specified, the frequency of user operation shall not exceed an intermittent duty of 20 operations in 10 min and extended sequences 30 operations in 1 h. These mechanical operating and endurance capabilities are independent of the electrical switching capabilities.





5.13.4 Shunt reactor current switching capability

This applies to circuit breakers intended for switching shunt reactors. Because shunt reactor switching is required for only certain circuit breaker applications, it is not included as a standard rating.

IEEE Std C37.015 [B28] can be used to evaluate the shunt reactor switching application for specific circuit breakers.

5.13.5 Line closing switching surge factor

The line closing switching surge factor has been removed as assigned rating because it cannot be verified by laboratory tests.

5.13.6 TRV line-to-ground capacitors and switchgear partial discharge

TRV capacitors shall be tested for partial discharge (PD) and the values recorded as part of the design record. For circuit breakers in metal-clad switchgear and metal-enclosed switchgear, the partial discharge (PD) requirements are outlined in IEEE Std C37.20.2 and IEEE Std C37.20.3.

6. Preferred ratings

6.1 General

Although this standard identifies preferred ratings, there are instances where a user must make a selection from several preferred or alternate ratings. The whole of Clause 6 and its subclauses is applicable to all types of circuit breakers, including circuit breakers applied to gas-insulated substations.

6.1.1 Summary of tables for required values and preferred ratings

Table number Table title Table description Ref.

clause Table 1 Limits of temperature Limits of Temperature and Temperature Rise 5.5.2 Table 2 Rated TRV parameters Rated TRV parameters 5.7.2.1 Table 3 Related required TRV

parameters Related required TRV parameters at fractions of the rated short circuit current

5.7.2.3

Table 4 Short-line fault standard values

Standard values of line characteristics for short-line faults 5.7.2.3.3

Table 5 ITRV values, Rated Voltage ≥ 100 kV

Standard values of ITRV – time to first peak voltage ti 5.7.2.3.4

Table 6 Insulation capability ratings Preferred insulation capability ratings and external insulation creepage

6.2

Table 7 Dielectric withstand ratings for gas insulated substations (GIS)

Preferred dielectric withstand ratings for circuit breakers applied in GIS

6.2

Table 8 Preferred ratings for class S1 circuit breakers

Preferred ratings for class S1 circuit breakers for cable systems below 100 kV

6.3

Table 9 TRV ratings, class S1: Terminal fault, Out of Phase

Preferred ratings of prospective TRV for class S1 circuit breakers rated below 100 kV for cable systems non-effectively grounded – Terminal fault and out-of-phase test duties, TRV representation by the two-parameter method

6.3






clause Table 10 TRV ratings, class S1,

T100, T60, T30, T10 Preferred ratings of prospective TRV for class S1 circuit breakers rated below 100 kV, for cable systems non-effectively grounded – T100, T60, T30, T10 test duties, TRV representation by the two-parameter method

6.3

Table 11 Capacitive current switching ratings, class S1

Preferred capacitive current switching ratings for class S1 circuit breakers for cable systems rated below 100 kV

6.3

Table 12 Preferred ratings for class S2 circuit breakers

Preferred ratings for class S2 circuit breakers for line systems rated below 100 kV, including circuit breakers applied in gas-insulated substations

6.4

Table 13 TRV ratings, class S2: Terminal fault, SLF, out-of-phase duties

Preferred ratings for prospective TRV for class S2 circuit breakers rated below 100 kV, including circuit breakers applied in gas-insulated substations for overhead line systems non-effectively grounded – Terminal fault, short-line fault and out-of-phase-duties, TRV representation by the two-parameter method

6.4

Table 14 TRV ratings, class S2: T100, T60, T30, T10

Preferred ratings for prospective TRV for class S2 circuit breakers rated below 100 kV, including circuit breakers applied in gas-insulated substations for overhead line systems non-effectively grounded – T100, T60, T30, T10 duties. TRV representation by the two-parameter method

6.4

Table 15 Capacitive current switching ratings, class S2

Preferred capacitive current switching ratings for class S2 circuit breakers rated below 100 kV for overhead line systems, including circuit breakers applied in gas-insulated substations

6.4

Table 16 Preferred ratings for circuit breakers ≥ 100 kV

Preferred ratings for circuit breakers rated 100 kV and above including circuit breakers applied in gas-insulated substations

6.5

Table 17 TRV ratings, ≥ 100 kV, kpp = 1.3: T100a, Terminal fault, SLF, Out of Phase

Preferred ratings of prospective TRV for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations for effectively grounded systems and ground faults with a first pole to clear factor, kpp = 1.3 at T100a, Terminal fault, Short-line fault, and Out-of-phase duties

6.5

Table 18 TRV ratings, ≥ 100 kV, kpp = 1.5: T100a, Terminal fault, SLF, Out of Phase

Preferred ratings of prospective TRV for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations for non-effectively ground systems (all faults) and also ungrounded faults in effectively ground systems, all with a first pole to clear factor of kpp = 1.5 at T100 a - Terminal fault, Short-line fault and Out-of-phase duties

6.5

Table 19 TRV ratings, ≥ 100 kV, kpp = 1.3: T100, T60, T30, T10

Preferred ratings of prospective TRV for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations, for effectively grounded system and grounded faults with a first pole to clear factor of kpp = 1.3 at T100, T60, T30 and T10

6.5

Table 20 TRV ratings, ≥ 100 kV, kpp = 1.5: T100, T60, T30, T10

Preferred ratings of prospective TRV for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations for non-effectively grounded systems (all faults) and also ungrounded faults in effectively grounded systems, all with a first pole to clear factor of kpp = 1.5 at T100 a – T100, T60, T30 and T10 test duties

6.5

Table 21 Capacitive current switching ratings, ≥100 kV

Preferred capacitive current switching ratings for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations

6.5

Table 22 Rated reclosing times for circuit breakers

Rated reclosing times for circuit breakers 6.6

Table 23 Rated control voltages for circuit breakers

Rated control voltages and their ranges for circuit breakers 6.7

Table 24 Schedule of operating endurance capabilities for circuit breakers

Schedule of operating endurance capabilities for circuit breakers

6.7






clause Table 25 Energy storage

requirements of operating mechanisms

Energy storage requirements of operating mechanisms 7.5.2.2

Table 26 Sound pressure level limits Sound pressure level limits 7.13.2 Table 27 Permissible noise exposure Permissible noise exposure 7.13.2 Table 28 Limits of radio influence

voltage Limits of radio influence voltage 7.16

Table 29 Thread dimensions for threaded terminal studs

Thread dimensions for threaded terminal studs 7.17.2

Table 30 Terminal mechanical loading

Terminal mechanical loading 7.18.4

Table 31 Accuracy class ratings for current transformers

Accuracy class ratings for current transformers used on or with class S2 circuit breakers

9.2.4

Table C.1 Site pollution severity Environmental examples by site pollution severity (SPS) class Annex C

Table C.1 Minimum creepage distance

Minimum nominal specific creepage distance by site pollution severity (SPS) class Annex C

Table D.1 Arc furnace circuit breaker operating capabilities

Operating capabilities of circuit breakers intended for arc furnace transformer switching

Annex D

Table F.1 Class E2 endurance Electrical endurance requirements on class E2 circuit breakers Annex F

6.2 Preferred maximum voltage and insulation capability ratings for circuit breakers

Preferred ratings for the insulation capability are given in terms of dielectric withstand test levels and external insulation creepage distance to ground in Table 6 and Table 7.





Table 6 —Insulation capability ratings (1)a

Line no.

Dielectric withstand test voltages Minimum creepage distance of external insulation to ground

(5)

Power frequency Lightning impulse (2) Switching impulse (2) Rated

maximum voltage

Ur

1 min dry 10 s wet Full wave withstand

(6)

Chopped wave 2 µs minimum

time to sparkover withstand

Withstand voltage terminal-to-ground with circuit breaker

closed

Withstand voltage terminal-to-terminal

on one phase with circuit breaker open

kV, rms kV, rms kV, rms kV, peak kV, peak kV, peak kV, peak mm in Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

16 17 18 19 20

21 22 23

4.76 8.25 15.0 15.5 15.5

25.8 25.8

25.8 (4) 27.0 38.0

38.0 38.0

38.0 (4) 48.3 48.3

72.5 123 145 170 245

362 550 800

19 36 36 50 50

60 60 60 60 80

80 80 80

105 105

160 230 275 325 425

555 860 960

(3) (3) (3) 45 45

50 50 50 (3) (3)

75 75 75 95 95

140 230 275 315 350

(3) (3) (3)

60 95 95

110 110

150 150 125 125 150

200 200 150 250 250

350 550 650 750 900

1300 1800 2050

(7) (7) (7) 142 (7)

194 (7) 161 (7) (7)

258 (7) 194 322 (7)

452 710 838 968 1160

1680 2320 2640

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

825 1175 1425

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

(3) (3) (3) (3) (3)

900 1300 1500

(3) (3) (3) 250 250

420 420 420 (3) (3)

610 610 610 780 780

1170 1990 2340 2750 3960

5850 8890 12900

(3) (3) (3)

9.84 9.84

16.5 16.5 16.5 (3) (3)

24.0 24.0 24.0 30.7 30.7

46.1 78.3 92.1 108 156

230 350 508

a Numbers in parenthesis refer to the information items in 6.2.1 for tables Table 6 and Table 7.





Table 7 —Insulation capability ratings for GIS a, b

Line no.

Rated maximum

voltage Ur

(kV, rms)

Rated power frequency withstand voltage (kV, rms)

Rated switching impulse withstand voltage (kV, peak) (2)

Rated lightning impulse withstand voltage (kV, peak) (2)

Test level Ud

Disconnect switch open gap

Test level (phase to ground)

Us

Test levels (phase to

phase)

Disconnect switch open gap (+ bias)

Test levels Up

Disconnect switch open

gap

Disconnect switch open gap (+ bias)

Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 1 15 36 95 2 15 50 110 3 38 60 150 4 38 80 200 5 72.5 140 160 325 375 6 100 185 210 450 520 7 123 230 265 550 630 8 145 275 315 650 750 9 170 325 375 750 860 10 245 c 425 490 900 1035 11 245 460 530 1050 1200 12 300 460 595 850 1275 700 (+245) 1050 1050 (+170) 13 362 c 500 650 850 1275 700 (+295) 1050 1050 (+205) 14 362 520 675 950 1425 800 (+295) 1175 1175 (+205) 15 420 650 815 1050 1575 900 (+345) 1425 1425 (+240) 16 550 740 925 1175 1760 900 (+450) 1550 1550 (+315) 17 800 960 1270 1425 2420 1100 (+650) 2100 2100 (+455)

NOTE—The rated values of this table differ from previous IEEE Std C37.122 and IEEE Std C37.06 values in the interest of harmonization with IEC values and increasing withstand margins across open disconnect switch gaps. AC open gap withstands have been increased from approximately 110% of line-to-ground withstand for all ratings, to approximately 115% for 245 kV and below and approximately 130% for ratings above 245 kV. This does not imply that equipment in presently in service needs to be replaced as older levels have proven adequate. a Numbers in parenthesis refer to the information items in 6.2.1 for Table 6 and Table 7. b Blank entries are not required. c These rows represent additional ratings not harmonized with other international standards.





6.2.1 Supplementary requirements for Table 6 and Table 7.

Numbers in parenthesis in Table 6 and Table 7 refer to the following correspondingly numbered items.

(1) For circuit breakers applied to gas-insulated substations, see Table 7.

(2) Lightning and switching impulse waveforms are defined in IEEE Std 4. All impulse values are phase-to-phase and phase-to-ground and across the open contacts, including vacuum circuit breakers when some preconditioning is required across open contacts. Special consideration should be addressed when performing chopped wave tests across open contacts of vacuum circuit breakers.

(3) Not required.

(4) These circuit breakers are intended for application on grounded wye distribution circuits equipped with surge arresters.

(5) Minimum creepage corresponds to pollution level: light as defined by Table C.1. Also see IEEE Std C37.010.

(6) For circuit breakers rated 100 kV and above, and those that have isolating gaps in series with the interrupting gaps, or have additional gaps in the resistor or capacitor circuits, the impulse test for interrupters and resistors shall be 75% of the value shown in Column 5 of Table 6. For other circuit breakers, the rating is not required.

(7) Chopped wave impulse not required for class S1 circuit breakers.





6.3 Preferred ratings for class S1 circuit breakers

Table 8, Table 9, Table 10, and Table 11 are applicable to class S1 circuit breakers (formerly referred to as indoor circuit breakers).

Table 8 —Preferred ratings for class S1 circuit breakers for cable systems below 100 kV a, b

Line no.

Rated maximum voltage (1)

Ur

Rated continuous current (6)

Rated short-circuit and short-time

current (Isc)

Rated interrupting

time (2)

Maximum permissible

tripping time delay

Rated closing and latching

current (3) (4)

kV, rms A, rms kA, rms ms Y, sec kA, peak Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6

1 2 3 4 5 6 7 8 9

10 11

12 13

14 15 16 17

18 19 20

4.76 4.76 4.76 4.76

8.25

15 15 15

15 15 15

27 27

38 38 38 38

72.5 72.5 72.5

1200, 2000 1200, 2000

1200, 2000, 3000, 4000 1200, 2000, 3000, 4000

1200, 2000, 3000

1200, 2000 1200, 2000 1200, 2000

1200, 2000, 3000 1200, 2000, 3000

1200, 2000, 3000, 4000

1200 1200, 2000, 3000

1200

1200, 2000 1200, 2000, 3000, 4000 1200, 2000, 3000, 4000

1200

1200, 2000, 3000 2000, 3000, 4000

31.5 40 50 63

40

20 25

31.5

40 50 63

16 25

16 25

31.5 40

25 31.5 40

50 or 83 50 or 83 50 or 83 50 or 83

50 or 83

50 or 83 50 or 83 50 or 83

50 or 83 50 or 83 50 or 83

50 or 83 50 or 83

50 or 83 50 or 83 50 or 83 50 or 83

50 or 83 50 or 83 50 or 83

2 2 2 2

2

2 2 2

2 2 2

2 2

2 2 2 2

2 2 2

82 104 130 164

104

52 65 82

104 130 164

42 65

42 65 82

104

65 82

104 a Numbers in parenthesis refer to the information items in 6.3.1 for Table 8, Table 9 and Table 10. b For preferred capacitive current switching ratings, see Table 11. For preferred dielectric ratings, see Table 6 and

Table 7.





Table 9 —TRV ratings, class S1: Terminal fault and out-of-phase a

Line no.


Ur Test duty

First pole to clear factor

kpp

Amplitude factor

kaf

TRV peak value

uc

Time t3

Time delay td

Reference voltage

u′

Time t′

RRRV uc /t3

kV, rms p.u. p.u. kV µs µs kV µs kV/µs Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10

1 2 3 4 5 6 7 8 9

10

11 12

4.76 4.76

8.25 8.25

15 15

27 27

38 38

72.5 72.5

Terminal fault Out-of-phase






1.5 2.5

1.5 2.5

1.5 2.5

1.5 2.5

1.5 2.5

1.5 2.5

1.4 1.25

1.4 1.25

1.4 1.25

1.4 1.25

1.4 1.25

1.4

1.25

8.2 12.1

14.1 21.1

25.7 38.3

46.3 68.9

65.2 97.0

124 185

44 88

52 104

66 132

92 184

109 218

165 330

7 13

8 16

10 20

14 28

16 33

25 50

2.7 4.0

4.7 7.0

8.6

12.8

15.4 23.0

21.7 32.3

41.4 61.7

21 43

25 50

32 64

45 90

53 105

80

160

0.19 0.14

0.27 0.20

0.39 0.29

0.50 0.37

0.60 0.45

0.75 0.56

a Numbers in parenthesis refer to the information items in 6.3.1 for Table 8, Table 9, and Table 10





Table 10 —TRV ratings, class S1: T100, T60, T30, T10 a

Line no.


Ur

Test duty First pole to clear factor

kpp

Amplitude factor

kaf

TRV peak value

uc

Time (5) t3

Time delay

td

Reference voltage

u′

Time t′

RRRV uc /t3


1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

17 18 19 20

21 22 23 24

4.76 4.76 4.76 4.76

8.25 8.25 8.25 8.25

15 15 15 15

27 27 27 27

38 38 38 38

72.5 72.5 72.5 72.5

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.4 1.5 1.6 1.7

1.4 1.5 1.6 1.7

1.4 1.5 1.6 1.7

1.4 1.5 1.6 1.7

1.4 1.5 1.6 1.7

1.4 1.5 1.6 1.7

8.2 8.7 9.3 9.9

14.1 15.1 16.2 17.2

25.7 27.5 29.4 31.2

46.3 49.5 52.9 56.2

65.2 69.8 74.5 79.1

124 133 142 151

44 19 10 10

52 23 11 11

66 29 15 15

92 40 20 20

109 48 24 24

165 73 36 36

7 3

1.5 1.5

8 3 2 2

10 4 2 2

14 6 3 3

16 7

3.6 3.6

25 11 5 5

2.7 2.9 3.1 3.3

4.7 5.1 5.4 5.7

8.6 9.2 9.8 10.4

15.4 16.5 17.6 18.7

21.7 23.3 24.8 26.4

41.4 44.4 47.4 50.3

21 9 5 5

25 11 6 6

32 14 7 7

44 19 10 10

53 23 12 12

80 35 18 18

0.19 0.46 0.93 0.99

0.27 0.66 1.47 1.56

0.39 0.95 1.96 2.08

0.50 1.25 2.53 2.69

0.60 1.45 3.1 3.3

0.75 1.82 3.94 4.19

a Numbers in parenthesis refer to the information items in 6.3.1 for Table 8, Table 9 and Table 10.





6.3.1 Supplementary requirements for Table 8, Table 9 and Table 10.

Numbers in parenthesis in Table 8, Table 9, and Table 10 refer to the following correspondingly numbered items.

(1) The voltage ratings are based on ANSI C84.1 where applicable and are the maximum voltages for which the circuit breakers are designed for and are the upper limit for operation.

(2) The ratings in this column are the maximum time interval to be expected during a circuit breaker opening operation between the instant of energizing the trip circuit and the interruption of the main circuit on the primary arcing contacts under certain specified conditions. The values may be exceeded under certain conditions as specified in 5.10.1 covering rated interrupting time.

(3) The tabulated value is for a 60 Hz system with an X/R of 17. This results in a rated closing and latching current (kA, peak) of the circuit breaker which is 2.6 times the rated short-circuit current. (If expressed in terms of kA, rms total current, the equivalent value is 1.55 times rated short-circuit current.) See 5.6.2.3 for more information.

(4) The tabulated value is for a 60 Hz system. For 50 Hz, the kA peak is 2.5 times the rated short-circuit current and the rms total current is 1.47 times the rated short circuit current. See 5.6.2.3 for other values.

(5) Synthetic tests can be performed to prove the capability of values of t3 in Column 6 of Table 10.

(6) The traditional North American continuous current ratings of 1200 A and 3000 A have been retained in this standard, while IEC prefers the continuous current ratings of 1250 A and 3150 A.





Table 11 —Capacitive current switching ratings, class S1 a, b

Line no.

Rated maximum

voltage Ur

Rated continuous

current

Class C0 (1) (2) general purpose circuit breakers

Class C1 and C2 (2) (4) Class C1 and C2 (2) (4) (6) (7) (8)

Rated isolated capacitor

bank current

Rated cable charging current

Back-to-back capacitor bank switching

Rated cable charging current

Rated isolated capacitor bank

current

Rated capacitor

bank current

Rated inrush current (3) (5) Preferred

rating peak value

Tested freq.

Alt. 1 rating

peak value

Tested freq.

Alt. 2 rating

peak value

Tested freq.

kV, rms A, rms A, rms A, rms A, rms A, rms A, rms kA, peak kHzb kA, peak kHzb kA, peak kHzb Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12 Col. 13 1 2 3 4 5 6 7 8 9

10

11 12 13

14 15 16

17 18 19

4.76 4.76 4.76

8.25 8.25 8.25

15 15 15 15

27 27 27

38 38 38

72.5 72.5 72.5

1200 2000 3000

1200 2000 3000

1200 2000 3000 4000

≤ 3000 ≤ 3000 ≤ 4000

≤ 4000 ≤ 4000 ≤ 4000

≤ 4000 ≤ 4000 ≤ 4000

10 10 10

10 10 10

25 25 25 25

31.5 31.5 31.5

50 50 50

50 50 50

400 400 400

250 250 250

250 250 250 250

160 160 160

100 100 100

100 100 100

630 1000 1600

630 1000 1600

630 1000 1600 1600

250 400 630

250 630 1000

250 630 1000

10 10 10

10 10 10

25 25 25 25

31.5 31.5 31.5

50 50 50

100 100 100

630 1000 1600

630 1000 1600

630 1000 1600 1600

250 400 630

250 630 1000

250 630 1000

15 15 25

15 15 25

15 15 25 25

15 15 25

20 20 20

25 25 25

2.0 1.3 1.3

2.0 1.3 1.3

2.0 1.3 1.3 1.3

4.3 4.3 4.3

4.3 4.3 4.3

3.4 3.4 3.4

6 6 6

6 6 6

6 6 6 6

6 6 6

6 6 6

6 6 6

0.8 0.5 0.3

0.8 0.5 0.3

0.8 0.5 0.3 0.3

2.0 1.3 0.8

2.0 0.8 0.5

2.0 0.8 0.5

14 17 22

18 22 28

24 30 38 38

19 25 31

21 33 43

22 34 43

1.8 1.4 1.1

2.4 1.9 1.5

3.0 3.0 2.0 2.0

7.0 5.0 4.0

7.0 5.0 4.0

7.0 5.0 4.0

a Numbers in parenthesis refer to the information in 6.3.2 for Table 11. b The rating is the kA value, and kHz is test frequency.





6.3.2 Supplementary requirements for Table 11 on preferred capacitive current switching ratings for class S1 cable systems circuit breakers rated below 100 kV

Numbers in parentheses in table refer to the following correspondingly numbered items.

(1) For class C0 (general-purpose) circuit breakers, no ratings for back-to-back capacitor switching applications are established. The capacitor bank or cable shall be “isolated” in accordance with 5.8.2 or 5.8.3 also see IEEE Std C37.012 [B27].

For class C0 (general-purpose) circuit breakers exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current on closing shall not exceed the lesser of either (1.41 times rated short-circuit current), or 50 000 A peak. The product of transient inrush current peak and transient inrush current frequency shall not exceed 20 kA·kHz.

(2) The circuit breaker shall be capable of switching any capacitive current of the ratings listed in the selected rating column by the user, in Table 11, at any voltage up to the rated maximum voltage.

(3) The rated transient inrush current peak is the highest magnitude of current that the circuit breaker shall be required to close at any voltage up to the rated maximum voltage and shall be as determined by the system as unmodified by the circuit breaker. The tested transient inrush current frequency shall be determined according to 5.8.5.

(4) For circuit breakers identified as a class C1 or C2 historically referred to as definite purpose, the manufacturer shall state the inrush current peak and frequency at which the circuit breaker meets Class C1 or C2 performance. The stated inrush current peak and frequency may be the preferred values from Table 11 or other values as determined by the manufacturer.

(5) Tests to prove capacitive switching ratings shall be performed according to the requirements of IEEE Std C37.09.

(6) The preferred ratings and alternates 1 or 2 ratings have different values. These values are for qualification of circuit breaker capacitance switching according to their capabilities. The preferred ratings lists the previous values indicated in ANSI C37.06-2000 [B1] and represent the standard values for circuit breakers. Alternate 1 ratings were added in particular for some ratings of vacuum and some other circuit breakers, and alternate 2 ratings represent the exceptional maximum values as seen by users and manufacturers in some world-wide applications. As of the time of the approval of this standard, only synthetic tests for alternate 2 are available in some laboratories.

(7) For class C1 and C2 circuit breakers exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current shall not exceed the rated closing and latching (peak withstand) capability of the circuit breaker. This is considered an infrequent event, and therefore the circuit breaker should be expected to handle this duty twice in the life time of the circuit breaker without requiring maintenance of the contacts.

6.4 Preferred ratings for class S2 circuit breakers for line systems below 100 kV

Table 12, Table 13, Table 14 and Table 15 are applicable to Class S2 circuit breakers (formerly referred to as outdoor circuit breakers)..





Table 12 —Preferred ratings for class S2 circuit breakers a, b

Line no.


Ur



current (Isc)

Rated interrupting

time (2)

Maximum permissible

tripping time delay

Y

Rated closing and

latching current (3)

kV, rms A, rms kA, rms ms sec kA, peak Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6

1 2 3 4

5 6

7 8 9 10 11

12 13 14

15 16 17 18 19

15.5 15.5 15.5 15.5

25.8 25.8

38.0 38.0 38.0 38.0 38.0

48.3 48.3 48.3

72.5 72.5 72.5 72.5 72.5

600, 1200 1200, 2000 1200, 2000

1200, 2000, 3000

1200, 2000 1200, 2000

1200, 2000 1200, 2000 1200, 2000 1200, 2000

1200, 2000, 3000

1200, 2000 1200, 2000

1200, 2000, 3000

1200, 2000 1200, 2000, 3000 1200, 2000, 3000 2000, 3000, 4000 2000, 3000, 4000

12.5 20 25 40

12.5 25

16 20 25

31.5 40

20 31.5 40

20 31.5 40 50 63

50 or 83 50 or 83 50 or 83 50 or 83

50 or 83 50 or 83

50 or 83 50 or 83 50 or 83 50 or 83 50 or 83

50 or 83 50 or 83 50 or 83

50 or 83 50 or 83 50 or 83 50 or 83 50 or 83

2 2 2 2

2 2

2 2 2 2 2

2 2 2

2 2 2 2 2

33 52 65

104

33 65

42 52 65 82

104

52 82

104

52 82

104 130 164

a Numbers in parenthesis refer to the information items in 6.4.1 on Table 12. b For preferred capacitive current switching ratings, see Table 15. For preferred dielectric ratings, see Table 6 and

Table 7.

6.4.1 Supplementary requirements for Table 12

Numbers in parenthesis in the table refer to the following correspondingly numbered items.

(1) The voltage ratings are based on ANSI C84.1 where applicable and are the maximum voltages for which the circuit breakers are designed and are the upper limit for operation.

(2) The rated interrupting time column is the maximum time interval to be expected during a circuit breaker opening operation on a symmetrical fault between the instant of energizing the trip circuit and the interruption of the main circuit on the primary arcing contacts under certain specified conditions. The value may be exceeded under certain conditions as specified in 5.10.1

(3) The tabulated values are for a 60 Hz system with an X/R of 17. This results in a rated closing and latching current (kA, peak) of the circuit breaker which is 2.6 times the rated short-circuit current. (If expressed in terms of kA, rms total current, the equivalent value is 1.55 times rated short-circuit current). For 50 Hz, peak is 2.5 times and rms total current is 1.47 times the rated short-circuit current. See 5.6.2.3 for more information.






Table 13 —TRV ratings for class S2: Terminal fault, short-line fault and out-of-phase duties a

Line no.


Ur Test duty


kpp

Amplitude factor

kaf

TRV peak value (4) (6)

uc

Time (2) t3

Time delay (3) td

Reference voltage

u′

Time t′

RRRV uc /t3


1 2 3 4 5 6 7 8 9

10 11 12

13 14 15

15.5 15.5 15.5

25.8 25.8 25.8

38.0 38.0 38.0

48.3 48.3 48.3

72.5 72.5 72.5

Terminal fault Short-line fault Out-of-phase





1.5 1.0 2.5

1.5 1.0 2.5

1.5 1.0 2.5

1.5 1.0 2.5

1.5 1.0 2.5

1.54 1.54 1.25

1.54 1.54 1.25

1.54 1.54 1.25

1.54 1.54 1.25

1.54 1.54 1.25

29.2 19.5 39.5

48.7 32.4 65.8

71.7 47.8 97.0

91.1 60.7 123

137 91.2 185

32 32 63

45 45 90

59 59 118

70 70 140

93 93 187

2 2 9 2 2

14 3 3

18

3.5 3.5 21 5 5

28

9.7 6.5

13.2

16.2 10.8 21.9

23.9 15.9 32.3

30.4 20.2 41.1

45.6 30.4 61.7

12 12 30

17 17 44

23 23 57

27 27 68

36 36 90

0.92 0.62 0.62

1.08 0.72 0.73

1.21 0.81 0.82

1.30 0.87 0.88

1.47 0.98 0.99

a Numbers in parenthesis refer to the informational items in 6.4.2for Table 13 and Table 14.





Table 14 —TRV ratings class S2: T100, T60, T30, T10 a

Line no.


Ur Test duty


kpp

Amplitude factor

kaf

TRV peak value (4)

uc

Time (2) (6) t3

Time delay (3) (5)

td

Voltage u′

Time (5) t′

RRRV uc /t3


1 2 3 4 5 6 7 8 9

10 11 12

13 14 15 16

17 18 19 20

15.5 15.5 15.5 15.5

25.8 25.8 25.8 25.8

38.0 38.0 38.0 38.0

48.3 48.3 48.3 48.3

72.5 72.5 72.5 72.5

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.5 1.5 1.5 1.5

1.54 1.65 1.74 1.80

1.54 1.65 1.74 1.80

1.54 1.65 1.74 1.80

1.54 1.65 1.74 1.80

1.54 1.65 1.74 1.80

29.2 31.3 33.0 34.2

48.7 52.1 55.0 56.9

71.7 76.7 81.0 83.8

91.1 97.5 103 107

137 146 155 160

32 21 13 13

45 30 18 18

59 40 24 24

70 47 28 28

93 62.5 36 36

2 [5] 3 2 2

2 [7] 5 3 3

3 [9] 6 4 4

3.5 [11] 7 4 4

5 [14] 9

5.5 5.5

9.7 10.4 11.0 11.4

16.2 17.4 18.3 19

23.9 25.6 27.0 28.0

30.4 32.5 34.3 35.5

45.6 48.8 51.5 53.3

12 [15] 10 6 6

17 [22] 15 9 9

23 [29] 19 12 12

27 [34] 23

13.5 13.5

36 [45]

30 17.5 17.5

0.92 1.47 2.61 2.70

1.08 1.74 3.06 3.16

1.21 1.93 3.41 3.53

1.30 2.07 3.67 3.80

1.47 2.34 4.27 4.42

a Numbers in parenthesis refer to the informational items in 6.4.2 for Table 13 and Table 14.





6.4.2 Supplementary requirements for Table 13 and Table 14

Numbers in parenthesis in Table 13 and Table 14 refer to the following correspondingly numbered items.


(2) Time t3 for out-of-phase is 2 times time t3 for terminal fault. [B11]). See B.2.3.2 for the calculation of t3.

(3) For out-of-phase fault, time td is 0.15 * t3. For terminal fault (T100) and short-line fault, time td is 0.05 * t3.

(4) The values of u c are calculated from Table 12 and Table 14. The formula to calculate the value of u c is based on uc = kpp × kaf × 3/2 × Ur.

(5) Where two values of the times td and t′ are given for terminal fault duty T100, separated by brackets, the second value in brackets can be used for testing if short-line fault tests are also made. If this is not the case, the times before the brackets apply.

(6) Synthetic tests can be performed to prove the capability of values of t3 in Column 6 of Table 14.





Table 15 —Capacitive current switching ratings, class S2 a, b, c

Line no.

Rated max.

voltage Ur

Rated cont.

current

Class C0 (1) (2) Circuit breakers—general

purpose Class C1 or Class C2 circuit breakers (2) (4)

Rated overhead

line current

Rated isolated

capacitor bank or cable

current

Rated capacitor bank

current (6)

Rated overhead

line current

Back-to-back capacitor bank switching

Rated capacitor bank

current (6)

Rated inrush current (3) (5) (8) Preferred rating (7)

peak value

Tested freq.

Alt. 1 rating (7)

peak value

Tested freq.

Alt. 2 rating (7)

peak value

Tested freq.

kV, rms A, rms A, rms A, rms A, rms A, rms A, rms kA, peak kHzc kA, peak kHzc kA, peak kHzc Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12 Col. 13

1 2 3

4 5 6

7 8 9

10 11 12

13 14 15 16

15.5 15.5 15.5

25.8 25.8 25.8

38 38 38

48.3 48.3 48.3

72.5 72.5 72.5 72.5

1200 2000 3000

1200 2000 3000

1200 2000 3000

1200 2000 3000

1200 2000 3000 4000

2 2 5

5 5 5

5 5 5

10 10 10

20 20 20 20

250 250 250

250 250 250

250 250 250

250 250 250

250 250 250 250

630 1000 1600

630 1000 1600

630 1000 1600

630 1000 1600

800 1000 1600 2000

100 100 100

100 100 100

100 100 100

100 100 100

100 100 100 100

630 1000 1600

630 1000 1600

630 1000 1600

630 1000 1600

630 1000 1600 2000

20 20 20

20 20 20

20 20 20

20 20 20

25 25 25 25

4.2 4.2 4.2

4.2 4.2 4.2

4.2 4.2 4.2

6.8 6.8 6.8

3.4 3.4 3.4 3.4

6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6

1.2 0.8 0.5

1.2 0.8 0.5

1.2 0.8 0.5

1.2 0.8 0.5

1.2 0.8 0.5 0.5

30 30 45

30 30 45

30 30 45

30 30 40

30 30 40 40

6.5 6.5 9.0

6.5 6.5 9.0

6.5 6.5 9.0

8.5 8.5

14.0

8.5 8.5

14.0 14.0

a Numbers in parenthesis refer to the information items in 6.4.3 for Table 15. b For preferred short-time current ratings, see Table 12. For preferred dielectric ratings, see Table 6 and Table 7. c The rating is the kA value, and kHz is test frequency.





6.4.3 Supplementary requirements for Table 15 on preferred capacitive current switching ratings for class S2 line systems circuit breakers rated below 100 kV

Numbers in parentheses in the Table 15 refer to the following correspondingly numbered items.

(1) For general purpose circuit breakers (sometimes referred to as Class C0), no established ratings for back-to-back capacitor switching applications. The capacitor bank or cable shall be “isolated in accordance with 5.8.2 or 5.8.3 and also see IEEE Std C37.012 [B27].

For general purpose circuit breakers (Class C0) exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current on closing shall not exceed the lesser of either 1.41 times rated short-circuit current or 50, 000 A peak. The product of transient inrush current peak and transient inrush current frequency shall not exceed 20 kA·kHz.

(2) The circuit breaker shall be capable of switching any capacitive current of the ratings listed in the selected rating column by the user, in Table 15 at any voltage up to the rated maximum voltage.


(4) For circuit breakers identified as a Class C1 or C2 (historically definite purpose) circuit breakers, the manufacturer shall state the inrush current peak and frequency at which the circuit breaker meets Class C1 or C2 performance. The stated inrush current peak and frequency may be the preferred values from Table 15 or other values as determined by the manufacturer.

(5) The transient inrush current in circuit breakers applied in GIS substations has a very high equivalent frequency (up to the MHz range, depending on the bus length) with an initial peak current of several thousand amperes (depending on the surge impedance of the bus). For reference, see IEEE Std C37.012 [B27]. Contact the manufacturer to determine the ability of the circuit breaker to withstand these inrush current stresses.

(6) Tests to prove capacitive switching ratings shall be performed according to the requirements IEEE Std C37.09.

(7) The preferred rating and alternatives 1 or 2 ratings have different values. These values are for qualification of circuit breaker capacitance switching according to their capabilities. Alternate 1 rating was added in particular for some ratings of vacuum and some other circuit breakers. Alternate 2 rating represents the exceptional maximum values seen by users and manufacturers in world-wide applications. As of the time of the approval of this standard, only synthetic tests for alternate 2 are available in some laboratories.

(8) For Class C1 and C2 circuit breakers exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current shall not exceed the rated closing and latching (peak withstand) capability of the circuit breaker. This is considered an infrequent event, and therefore the circuit breaker should be expected to handle this duty twice in the life time of the circuit breaker without requiring maintenance of the contacts.

6.5 Preferred ratings for circuit breakers 100 kV and above

Table 16, Table 17, Table 18, Table 19, Table 20, and Table 21 are applicable to circuit breakers rated 100 kV and above, including circuit breakers applied to gas-insulated substations.





Table 16 — Preferred ratings for circuit breakers rated ≥ 100 kVa

Line No.


Ur



current

Rated interrupting

time (2)

Maximum permissible

tripping time delay

Rated closing and

latching current (3)

kV, rms A, rms kA, rms (Isc) ms Y, s kA, peak Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 1 2 3 4 5 6 7 8 9

10 11 12 13 14 15

16 17 18 19 20

21 22 23

24 25 26

27 28 29

123 123 123 123

145 145 145 145 145

170 170 170 170 170 170

245 245 245 245 245

362 362 362

550 550 550

800 800 800

1200, 2000 2000, 3000, 4000 2000, 3000, 4000 2000, 3000, 4000

1200, 2000

1600, 2000, 3000 2000, 3000 2000, 3000

2000, 3000, 4000

1600, 2000 2000, 3000

2000, 3000, 4000, 5000 2000, 3000, 4000, 5000

3000, 4000, 5000 4000, 5000

1600, 2000, 3000

2000, 3000 2000, 3000

2000, 3000, 4000, 5000 3000, 4000, 5000

2000, 3000 2000, 3000

2000, 3000, 4000

2000, 3000 3000, 4000 3000, 4000

2000, 3000 3000, 4000 3000, 4000

31.5 40 50 63

31.5 40 50 63 80

31.5 40 50 63 80 100

31.5 40 50 63 80

40 50 63

40 50 63

40 50 63

50 50 50 50

33 or 50 33 or 50 33 or 50 33 or 50 33 or 50

33 or 50 33 or 50 33 or 50 33 or 50 33 or 50 33 or 50

33 or 50 33 or 50 33 or 50 33 or 50 33 or 50

33 or 50 33 or 50 33 or 50

33 33 33

33 33 33

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

82 104 130 164

82 104 130 164 208

82 104 130 164 208 260

82 104 130 164 208

104 130 164

104 130 164

104 130 164

a Numbers in parenthesis refer to the informational items in 6.5.1 for Table 16.






Numbers in parenthesis in the table refer to the information correspondingly numbered items.

(1) The voltage ratings are based on ANSI C84.1where applicable and are the maximum voltages for which the circuit breakers are designed and are the upper limit for operation.

(2) The rated interrupting time column is the maximum time interval to be expected during a circuit breaker opening operation on symmetrical fault between the instant of energizing the trip circuit and the interruption of the main circuit on the primary arcing contacts under certain specified conditions. The value may be exceeded under certain conditions as specified in 5.10.1.

(3) The tabulated values are for a 60 Hz system with an X/R of 17. This results in a rated closing and latching current (kA, peak) of the circuit breaker which is 2.6 times the rated short-circuit current. (If expressed in terms of kA, rms total current, the equivalent value is 1.55 times rated short-circuit current.). For 50 Hz, the rated closing and latching current (kA, peak) of the circuit breaker is 2.5 times the rated short-circuit current. (If expressed in terms of kA, rms total current, the equivalent value is 1.47 times the rated short-circuit current.). See 5.6.2.3 for more information.






Table 17 —TRV ratings, circuit breakers ≥100 kV kpp = 1.3: T100a, Terminal fault, Short-line fault, and Out-of-phase Standard values of TRV represented by four parameters for terminal fault, short-line fault and out-of-phase fault duties.

Line no.


Ur

Test duty (9) (10) (11)


kpp

Amplitude factor

kaf

First reference voltage

u1

Time t1


uc

Time (2) t2

Time delay

(3) td

Voltage u′

Time t′

RRRV u1 /t1

kV, rms p.u. p.u. kV µs kV µs µs kV µs kV/µs Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12

1 2 3

4 5 6

7 8 9

10 11 12

13 14 15

16 17 18

19 20 21

123 123 123

145 145 145

170 170 170

245 245 245

362 362 362

550 550 550

800 800 800








1.3 1.0 2.0

1.3 1.0 2.0

1.3 1.0 2.0

1.3 1.0 2.0

1.3 1.0 2.0

1.3 1.0 2.0

1.3 1.0 2.0

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

98 75 151

115 89 178

135 104 208

195 150 300

288 222 443

438 337 674

637 490 980

49 38 98

58 44 116

68 52 136

98 75 196

144 111 288

219 168 438

318 245 636

183 141 251

215 166 296

253 194 347

364 280 500

538 414 739

817 629 1120

1190 914

1630

196 152 392

232 176 464

272 208 544

392 300 784

576 444

1152

876 672

1752

1272 980

2544

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

49 38 75

58 44 89

68 52 104

98 75 150

144 111 222

219 168 337

319 245 490

27 21 51

31 24 60

36 28 70

51 40 99

74 57 146

112 86 221

161 124 320

2 2

1.54 2 2

1.54 2 2

1.54 2 2

1.54 2 2

1.54 2 2

1.54 2 2

1.54 a Numbers in parenthesis refer to the information items in 6.5.2 for Table 17, Table 18, and Table 19.





Table 18 —TRV ratings ≥ 100 kV, kpp = 1.5 : T100a - Terminal fault, Short-line fault and Out-of-phase

Standard values of TRV represented by four parameters for terminal fault, short-line fault and out-of-phase fault test duties.

Line no.

Rated max.

voltage (1) Ur

Test duty (9) (10) (11)


kpp

Amplitude factor

kaf


u1

Time TRV peak

value (4) (8) uc

Time (2) t2

Time delay (3)

td

Voltage u′

Time t′

RRRV u1 /t1

kV, rms p.u. p.u. kV µs kV µs µs kV µs kV/µs Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12

1 2 3 4 5 6 7 8 9

10 11 12

13 14 15

16 17 18

19 20 21

123 123 123

145 145 145

170 170 170

245 245 245

362 362 362

550 550 550

800 800 800








1.5 1.0 2.5

1.5 1.0 2.5

1.5 1.0

2.0 (6)

1.5 1.0

2.0 (6)

1.5 1.0

2.0 (6)

1.5 1.0

2.0 (6)

1.5 1.0

2.0 (6)

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

1.40 1.40 1.25

113 75 188

133 89 222

156 104 208

225 150 300

333 222 443

505 337 674

735 490 980

56 38 113

67 44 133

78 52 135

113 75 195

166 111 288

253 168 437

367 245 636

211 141 314

249 166 370

291 194 347

420 280 500

621 414 739

943 629

1120

1370 914

1630

224 152 452

268 178 532

312 208 541

452 300 779

664 444

1150

1012 674

1750

1468 980

2550

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

2 2 2

57 38 94

67 44

111

78 52

104

113 75

150

167 111 222

253 168 337

368 245 490

30 21 51

35 24 68

41 28 70

58 40 99

85 57 146

128 86 221

186 124 320

2 2

1.67

2 2

1.67

2 2

1.54

2 2

1.54

2 2

1.54

2 2

1.54

2 2

1.54 a Numbers in parenthesis refer to the informational items in 6.5.2 for Table 17, Table 18, and Table 19.





Table 19 —TRV ratings ≥ 100 kV kpp = 1.3: T100, T60, T30 and T10 a Standard values of TRV represented by four parameters (test duties T100, T60) and two parameters (test duties T30, T10).

Line No.

Rated max. voltage (1)

Ur Test duty

Amplitude factor

kaf


u1

Time t1


uc

Time (2) t2

Time t3

Time delay (5)

td Voltage

u′ Time (5)

t′ RRRV u1 /t1 or uc / t3

kV, rms p.u. kV μs kV μs μs μs kV μs kV/µs Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12

1 2 3 4

5 6 7 8

9 10 11 12

13 14 15 16

17 18 19 20

21 22 23 24

25 26 27 28

123 123 123 123

145 145 145 145

170 170 170 170

245 245 245 245

362 362 362 362

550 550 550 550

800 800 800 800

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

1.40 1.50

1.54 (7) 1.76 (7)

98 98 — —

115 115 — —

135 135 — —

195 195 — —

288 288 — —

438 438 — —

636 636 — —

49 33 — —

58 38 — —

68 45 — —

98 65 — —

144 96 — —

219 146 — —

318 212 — —

183 196 201 230

215 231 237 272

253 271 278 320

364 390 400 459

538 576 592 676

817 876 899 1030

1190 1270 1320 1500

196 99 — —

232 114 — —

272 135 — —

392 195 — —

576 288 — —

876 438 — —

1272 636 — —

— — 40 33

— — 47 39

— — 56 46

— — 80 66

— — 118 97

— — 180 147

— — 262 214

2 [14] 2 [10]

6 5

2 [16] 2 [12]

7 6

2 [19] 2 [14]

8 7

2 [7] 2 [20]

12 10

2 [40] 2 [29]

18 15

2 [61] 2 [44]

27 22

2 [89] 2 [64]

39 32

49 49 67 77

58 58 79 91

68 68 93 106

98 98 133 153

144 144 197 226

219 219 300 344

319 319 436 500

27 [8] 18 [26]

19 16

31 [45] 21 [31]

23 19

36 [53] 25 [36]

27 22

51 [76] 35 [52]

39 32

74 [112] 50 [77]

57 47

112[171] 75 [117]

87 71

161 [248] 108 [170]

126 103

2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7

a Numbers in parenthesis refer to the informational items in 6.5.2 for Table 17, Table 18, and Table 19.





6.5.2 Supplementary requirements for Table 17, Table 18, and Table 19

Numbers in parenthesis in the tables refer to the following correspondingly numbered items.


(2) Time t2 for out-of-phase is 2 times time t2 for terminal fault [B11]. See B.2.3.2 for the calculation of t2.

(3) For out-of-phase, time td is the same as for terminal fault and short-line fault.

(4) The values of uc are calculated from Table 16, Table 17, Table 18, and Table 19. The value is calculated such as: uc = kaf × kpp × 3/2 × Ur

(5) Where two values of the times td and t′ are given, the second value in brackets can be used for testing if short-line fault tests are required. If this is not the case, the first value before the brackets applies.

(6) Table 18 only: for rated voltages of 170 kV and higher systems are considered to be effectively grounded, therefore the recovery voltage for out-of-phase is 2.0 times the rated maximum voltage Ur divided by √3.

(7) Table 19 only: In the process of harmonization with IEC 62271-100 [B11], values of T30 and T10 with

a first pole to clear factor kpp of 1.3 were changed in the 2009 edition of IEEE Std C37.06. At T30, the amplitude factor kaf is changed to 1.54 instead of 1.58 and for T10 the amplitude factor kaf is increased to 1.76 (it corresponds to an amplitude factor of 0.9 × 1.7 with kpp = 1.5). The numbers on these lines are thus harmonized.

(8) Values of TRV terminal fault were not changed from the previous publication ANSI C37.06-2000 [B1] but were translated to the two- or four-parameter representation with improved accuracy.

(9) Since the out-of-phase switching duty is required for only certain circuit breaker applications, the specification of a rated out-of-phase making and breaking current is not mandatory

(10) The assigned out-of-phase switching current rating is the maximum out-of-phase current that the circuit breaker shall be capable of switching at a rated power frequency, out-of-phase recovery voltage equal to 2 times the rated maximum voltage for grounded systems, and 2.5 times the rated maximum voltage for ungrounded systems (see IEEE Std C37.09). If a circuit breaker has an assigned out-of-phase switching current rating, the preferred rating shall be 25% of the rated (symmetrical) short-circuit current expressed in kA, unless otherwise specified.

(11) In the case of short-line-fault, the TRV parameters are those of the supply circuit.





Table 20 —TRV ratings ≥ 100 kV, kpp = 1.5: T100 a – T100, T60, T30 and T10 a Standard values of TRV represented by four parameters (T100, T60) and two parameters (T30, T10)

Line No.


Ur

Test duty Amplitude

factor kaf


u1

Time t1


uc

Time t2

Time t3

Time delay (3) td

Voltage u′

Time (3) t′

RRRV u1 /t1, or

uc / t3

kV, rms p.u. kV µs kV µs µs µs kV µs kV/µs Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12

1 2 3 4 5 6 7 8 9

10 11 12

13 14 15 16

17 18 19 20

21 22 23 24

25 26 27 28

123 123 123 123

145 145 145 145

170 170 170 170

245 245 245 245

362 362 362 362

550 550 550 550

800 800 800 800

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

T100 T60 T30 T10

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

1.40 1.50 1.58 1.64

113 113 — —

133 133 — —

156 156 — —

225 225 — —

333 333 — —

504 504 — —

735 735 — —

56 38 — —

67 44 — —

78 52 — —

113 75 — —

166 111 — —

253 168 — —

367 245 — —

211 226 238 247

249 266 281 291

291 312 329 341

420 450 474 492

621 665 701 727

943 1010 1060 1110

1370 1470 1550 1610

224 114 — —

268 132 — —

312 156 — —

452 225 — —

664 333 — —

1012 504 — —

1468 735 — —

— — 48 35

— — 56 42

— — 66 49

— — 95 70

— — 140 104

— — 213 158

— — 310 230

2 [16] 2 [11]

7 5

2 [19] 2 [13]

8 6

2 [22] 2 [16]

10 7

2 [32] 2 [23]

14 11

2 [47] 2 [33]

21 16

2 [71] 2 [51]

32 24

2 [103] 2 [74]

46 34

57 57 79 82

67 67 94 97

78 78 110 114

113 113 158 164

167 167 234 242

253 253 355 368

368 368 516 536

30 [44] 21 [30]

23 17

35 [52] 24 [35]

27 20

41 [61] 28 [42]

32 24

58 [88] 40 [60]

46 34

85 [130] 58 [89]

68 50

128 [197] 86 [135]

103 76

186 [287] 125 [196]

150 111

2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7 2 3 5 7

a Numbers in parenthesis refer to the information items in 6.5.3 for Table 20.






Numbers in parenthesis in the tables refer to the following correspondingly numbered items. (1) The voltage ratings are based on ANSI C84.1 where applicable and are the maximum voltages for

which the circuit breakers are designed and are the upper limit for operation.

(2) The values of uc are calculated from Table 16 and Table 20.

(3) The value is calculated as: uc = kaf × kpp × 3/2 × Ur.

(4) Where two values of the times td and t′ are given, the second value in brackets can be used for testing if short-line fault tests are required. If this is not the case, the first values before the brackets apply.

(5) Values of TRV terminal fault were not changed from the previous publication IEEE Std C37.06-2000 [B1] but were translated to the two or four-parameter representation with improved accuracy.





Table 21 —Capacitive current switching ratings ≥ 100 kV a, b, c, d

Line no.

Rated max.

voltage Ur

Rated cont.

current

Class C0 circuit breakers (1) (2)

Class C1 or Class C2 (2 ) (4) (6) Class C1 or Class C2 circuit breakers (2) (4) (9)

Rated overhead

line current

Rated capacitor bank or

cable current

Rated isolated

capacitor bank current

Rated overhead

line current

Back-to-back capacitor bank switching (8) Rated back-to-back capacitor bank current

(6)

Rated inrush current (3) (5) Preferred rating (7)

peak value

Tested freq.

Alt. 1 rating (7)

peak value

Tested freq.

Alt. 2 rating (7)

peak value

Tested freq.

Alt. 3 rating (7)

peak value

Tested freq.

kV, rms A, rms A, rms A, rms A, rms A, rms A, rms kA, peak kHzc kA, peak kHzc kA, peak kHzc kA, peak kHzc Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7 Col. 8 Col. 9 Col. 10 Col. 11 Col. 12 Col. 13 Col. 14 Col. 15

1

2

3

4

5

6

7

123

145

170

245

362

550

800

(9)

(9)

(9)

(9)

(9)

(9)

(9)

50

80

100

160

250

400

900

50

80

100

160

250

400

500

1200

1200

1200

1200

1200

1000

1000

160

160

160

200

315

500

900

700

700

700

700

800

800

800

16

16

20

20

25

25

25

4.3

4.3

4.3

4.3

4.3

4.3

4.3

6

6

6

6

6

6

6

2 2 2 2 2 2 2

25

25

25

25

20

20

20

13

13

13

13

21

21

21

60

60

60

60

65

65

65

8.5

8.5

8.5

8.5

8.5

8.5

8.5

a Numbers in parenthesis refer to the information items in 6.5.4 for Table 21. b For preferred short-time ratings, see Table 16. For preferred dielectric ratings, see Table 6 and Table 7. c The rating is the kA value, and kHz is test frequency.





6.5.4 Supplementary requirements items for Table 21 on preferred capacitive current switching ratings for circuit breakers rated 100 kV and above, including circuit breakers applied in gas-insulated substations

Numbers in parentheses in the table refer to the following correspondingly numbered items.

(1) For general-purpose circuit breakers (Class C0) no ratings for back-to-back capacitor switching applications are established. The capacitor bank or cable shall be “isolated” in accordance with 5.8.2 or 5.8.3 and also see IEEE std C37.012 [B27].

For general-purpose circuit breakers (Class C0) exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current on closing shall not exceed the lesser of either 1.41 times rated short-circuit current or 50 kA peak. The product of transient inrush current peak and transient inrush current frequency shall not exceed 20 kA·kHz.

(2) The circuit breaker shall be capable of switching any capacitive current of the ratings listed in the selected rating column by the user, in Table 21, at any voltage up to the rated maximum voltage.


(4) For circuit breakers identified as a Class C1 or C2 (historically referred to as definite purpose), the manufacturer shall state the inrush current peak and frequency at which the circuit breaker meets Class C1 or C2 performance. The stated inrush current peak and frequency may be the preferred values from Table 21 or other values as determined by the manufacturer and the user.

(5) The transient inrush current in circuit breakers applied in GIS substations has a very high equivalent frequency (10s or 100s of MHz, depending on the bus length) with an initial peak current of several thousand amperes (depending on the surge impedance of the bus). Although this observation is primarily of academic interest, it demonstrates that there is no practical upper limit for application. For reference, see IEEE Std C37.012 [B27].

(6) Tests to prove capacitive switching ratings shall be performed according to the requirements of IEEE Std C37.09.

(7) The preferred ratings are those from the previous revision of IEEE Std C37.06-2009. Alternates 1, 2, or 3 ratings have different values for qualification of circuit breaker capacitance switching capabilities.

The preferred ratings represent the usual values that have historically been used for circuit breakers previously referred to as definite purpose circuit breakers.

Alternate 1 rating was added in particular for some ratings of circuit breakers. The values of inrush current magnitude and inrush frequency are generally lower than the preferred rating (historical values).

Alternates 2 and 3 ratings represent alternatives of exceptional maximum capacitance switching values as seen in a survey of users and manufacturers in world-wide applications.

Alternate 2 rating was developed by taking the 90th percentile of the inrush current frequency seen in the survey and matching it with the corresponding inrush current magnitude at the 90th percentile inrush frequency.

Similarly, alternate 3 rating was developed by taking the 90th percentile of the inrush current magnitude seen in the survey and matching it with the corresponding inrush current frequency at the 90th percentile inrush current magnitude. These values of inrush current magnitude and inrush frequency are generally higher than preferred rating (historical values). All values have been rounded.

It is necessary to choose which alternative shall apply to the circuit breaker. Refer to application guides IEEE Std C37.012 [B27] for guidance on this selection.





(8) For Class C1 and C2 circuit breakers exposed to transient inrush currents from nearby capacitor banks during fault conditions, the capacitance transient inrush peak current shall not exceed the rated closing and latching (peak withstand) capabilities of the circuit breaker. This is considered an infrequent event, and therefore the circuit breaker should be expected to handle this duty twice in its life time without requiring maintenance of the contacts.

(9) This current rating column is applicable to all ratings of preferred continuous currents.

6.6 Rated reclosing times for circuit breakers

Table 22 defines rated reclosing times for circuit breakers.

Table 22 —Rated reclosing times for circuit breakers a

Circuit breaker ratings Rated Reclosing time (1) (s)

Class S1 circuit breakers less than 100 kV; 1200 A, 2000 A, 3000 and 4000 A 0.3

Class S2 or circuit breakers rated 100 kV and above 15.5 kV and above 0.3

a Numbers in parenthesis refer to the items in 6.6.1 for Table 22.


Numbers in parentheses in Table 22 refer to the following correspondingly numbered items.

(1) Circuit breakers rated for reclosing shall be capable of reclosing within these times on an instantaneous reclosing cycle, O + 0.3 s + CO, when operating in conjunction with an automatic reclosing device. These time-values are based on maintaining rated control voltage or operating pressure at the operating mechanism. In case the control voltage or pressure drops to 90% of rated voltage or pressure, the reclosing times will be increased to 110% of the above values. Consult the manufacturer for special reclosing requirements. Reclosing time is defined in Clause 3. Some circuit breakers require a minimum time requirement between the opening and next closing of the circuit breaker to allow proper mechanical functioning of the mechanism. This minimum time requirement may be implemented internally by circuit breaker control circuitry or externally by means of protection and control circuitry; and in either case must be implemented to prevent damage to, or incorrect operation of the circuit breaker (refer to 5.10.2).

A time in addition to the minimum mechanical reclose time, and known as “tmin” may be imposed by the circuit breaker characteristics; however it is not a time that can be tested on-site. Time “tmin” is commonly known as the dead time, i.e., the interval of time between final arc extinction in all poles and first reestablishment of current in any pole in the subsequent closing operation. The mechanical reclose time is important from the perspective of installation and maintenance. The time “tmin” is important from the perspective of system protection and control.

6.7 Control voltage ranges for circuit breakers

Operating mechanisms are designed for the rated control voltages listed with operational capabilities throughout the indicated voltage ranges to accommodate variations in source regulation, coupled with dc battery low charge levels, as well as dc battery high charge levels maintained with floating charges. The voltage is measured at the point of user connection to the circuit breaker [see items (12) and (13)] with no operating current flowing, and the minimum voltage is measured with operating current flowing.





Table 23 —Rated control voltages for circuit breakers a (10) (12) (13)

Line No.

Rated control voltage

(11)

DC voltage ranges (1) (2) (3) (5) (8) (9) (14)

V, dc Rated control

voltage (14)

(60 Hz)

Alternating current voltage ranges

(1) (2) (3) (4) (8) (14) Closing, energy storage, tripping, and auxiliary

functions

Closing, energy storage and auxiliary functions Opening

functions All types Class S1

circuit breakers

Class S2 circuit breakers and circuit

breakers rated 100 kV and above

Single phase Single phase

Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 1 2 3 4 5 6

24 (6) 48 (6) 125 250 — —

— 38-56

100-140 200-280

— —

— 36-56

90-140 180-280

— —

14-28 28-56 70-140

140-280 — —

120 240

104-127 (7) 208-254 (7)

Polyphase Polyphase 208Y/120

240 180Y/104–220Y/127

208–254

a Numbers in parenthesis refer to the items in 6.7.1 Information items for Table 23.


Numbers in parentheses in Table 23 refer to the following correspondingly numbered items.

(1) Electrically operated motors, contactors, solenoids, valves, and the like, need not carry a nameplate voltage rating that corresponds to the control voltage rating shown in the table as long as these components perform the intended duty cycle (usually intermittent) in the voltage range specified.

(2) Relays, motors, or other auxiliary equipment that functions as a part of the control for a device shall be subject to the voltage limits imposed by this standard, whether mounted at the device or at a remote location.

(3) Circuit breaker devices, in some applications, may be exposed to control voltages exceeding those specified here due to abnormal conditions such as abrupt changes in line loading. Such applications require specific study, and the manufacturer should be consulted. Also, application of switchgear devices containing solid-state control, exposed continuously to control voltages approaching the upper limits of ranges specified herein, require specific attention, and the manufacturer should be consulted before application is made.

(4) Includes supply for pump or compressor motors.

(5) It is recommended that the coils of closing, auxiliary, and tripping devices that are connected continually to one dc potential should be connected to the negative control bus to minimize electrolytic deterioration.

(6) 24 V or 48 V tripping, closing, and auxiliary functions are recommended only when the device is located near the battery or where special effort is made to ensure the adequacy of conductors between battery and control terminals. 24 V closing is not recommended.

(7) Includes heater circuits.

(8) Voltage ranges apply to all closing and auxiliary devices when cold. Circuit breakers utilizing standard auxiliary relays for control functions may not comply at lower extremes of voltage ranges when relay coils are hot, as after repeated or continuous operation.

(9) DC control voltage sources, such as those derived from rectified alternating current, may contain sufficient inherent ripple to modify the operation of control devices to the extent that they may not function over the entire specified voltage ranges.

(10) This table also applies for circuit breakers in gas-insulated substation installations.





(11) In cases where other operational ratings are a function of the specific control voltage applied, tests in IEEE Std C37.09 may refer to the “rated control voltage.” In these cases, tests shall be performed at the levels in Column 1.

(12) For a class S2 circuit breaker, the point of user connection to the circuit breaker is the secondary terminal block point at which the wires from the circuit breaker operating mechanism components are connected to the user’s control circuit wiring.

(13) For removable circuit breakers used in enclosures, the point of user connection to the circuit breaker is either the secondary disconnecting contact (where the control power is connected from the stationary housing to the removable circuit breaker) or the terminal block point in the housing nearest to the secondary disconnecting contact.

(14) The voltage ratings of protective relays and other devices used to initiate operation of the circuit breaker controls may have voltage requirements other than of the circuit breaker. All other capabilities of these devices shall be as required by IEEE Std C37.90.

6.8 Circuit breaker operation and operating endurance capabilities

Two classes of mechanical endurance are provided: normal mechanical endurance, class M1, and extended mechanical endurance, class M2. Class M1 is required for all circuit breakers, Table 24 identifies the schedule of operating endurance capabilities for circuit breakers class M1. Class M2 is an optional rating which is intended for frequently operated circuit breakers with special service requirements and limited maintenance. Class M2 requires 10 000 no-load mechanical operations capability for all ratings described in Table 24 below.

NOTE—Circuit breaker class M2 is intended to harmonize with IEC 62271-100 circuit breaker class M2. The minimum required endurance capability demonstrated by class M1 is intended to carry forward historical endurance capabilities established in earlier standards, it is not equivalent to the IEC mechanical endurance capability class M1.

Table 24 — Schedule of operating endurance capabilities for circuit breakers a (1) (6) (7)

Line No.

Circuit breaker ratings Number of operations (each operation is

comprised of one closing plus one opening) (3) (4) (5)

Rated maximum

voltage

Rated continuous current

Rated short-circuit current

Between servicing

(2)

No-load mechanical

(8)b, c

Rated continuous

current switching (9)

Inrush current

switching (10)

kV, rms A, rms kA, rms Col. 1 Col. 2 Col. 3 Col. 4 Col. 5 Col. 6 Col. 7

Class S1 circuit breakers 1 2 3 4 5

4.76, 15 4.76, 8.25, 15

15 27 38

1200, 2000 1200, 2000, 3000, 4000 1200, 2000, 3000, 4000

1200, 2000, 3000 1200, 2000, 3000, 4000

20, 25, 31.5 40, 50

63 16, 25

16, 25, 31.5, 40

2000 1000 500 500 250

10 000 5000 2000 2500 2000

1000 500 500 200 100

750 400 400 100 100

Class S2 circuit breakers (11) 6 15.5 and

above All All 500 2000 100 100

Circuit breakers 100 kV and above (11) 7 All All All 500 2000 100 100

a Numbers in parenthesis refer to the items in 6.8.1 and Table 24. b Circuit breaker class M1, normal mechanical endurance according to the values given in Col. 5 are the minimum required no-load mechanical endurance with servicing at intervals no more frequently than given in Col. 4. c Circuit breaker class M2, special service requirements, is optional for any circuit breaker and consists of 10 000 operations (for all ratings) with limited maintenance. Class M2 meets the requirements for class M1.






Numbers in parentheses in the table refer to the following correspondingly numbered items.

(1) Table 24 may be used as a guide for applying circuit breakers to switching conditions that differ from those specified. In such cases, the number of operations may differ from those tabulated, but the cumulative duty on the circuit breaker must be within the service capability as required in 5.6.2.5.

(2) Servicing consists of cleaning, tightening, adjusting, lubricating, etc., as recommended by the manufacturer, and assumes usual service conditions. Maintenance intervals are usually based on both an elapsed time and a number of operations, whichever occurs sooner as per the manufacturer requirements.

(3) With rated control voltage applied. See Table 23.

(4) For frequency of operation see 5.13.3.

(5) No functional parts shall have been replaced prior to completion of the specified number of operations.

(6) After completion of the specified number of operations, the circuit breaker shall be capable of withstanding rated maximum voltage in the open position, and shall be capable of carrying rated continuous current, at rated frequency, at a stable temperature until maintained. The limits of temperature rises may be exceeded. The circuit breaker shall be deemed to be capable of carrying its rated continuous current at a stable temperature until maintained if the resistance of the continuous carrying circuit, when measured with a DC current source where at least 100 A is flowing, is less than 200% of the maximum value measured prior to the specified number of operations.

(7) If a short-circuit operation occurs before the completion of the listed operations, maintenance is recommended and possible functional part replacement may be necessary, depending on previous accumulated duty, fault magnitude, and expected future operations.

(8) Requirements are based on specified maintenance intervals in accordance with Column 4.

(9) When closing and opening current equal to rated continuous current at rated maximum voltage with power factor between 80% leading and 80% lagging.

(10) When closing current equal to 600% of rated continuous current at rated maximum voltage with power factor of 30% or less and when opening current equal to rated continuous current at rated maximum voltage with power factor between 80% leading and 80% lagging.

(11) Classes S1 and S2 are for circuit breakers below 100 kV. For 100 kV and above, all circuit breakers have the same characteristics, even if installed in indoor or outdoor substations such as GIS. Ratings of circuit breakers class S2 also apply for circuit breakers in gas-insulated substation installations.

7. Construction and functional components

7.1 Requirements for liquids in switchgear

The manufacturer shall specify the type and the required quantity and quality of the liquid used in switchgear.

The manufacturer shall provide the user with necessary instructions for renewing the liquid and maintaining its required quantity and quality.

For oil-filled switchgear, new insulating oil shall comply with IEEE Std C57.106, IEC 60296:2003 [B6], or ASTM D3487.





7.2 Requirements for gases in circuit breakers

The manufacturer shall specify the type and the required quantity and quality of the gas to be used in switchgear. The weight of the gas contained with each circuit breaker or switchgear assembly shall be recorded at the ambient filling condition required during operation or rated condition and shall appear on the nameplate. If the circuit breaker is shipped with less than its rated filling pressure, the weight of the gas contained in the equipment leaving the factory must be recorded on the production test report.

The manufacturer shall provide the user with necessary instructions for renewing the gas and maintaining its required quantity and quality. This requirement does not apply to sealed pressure systems.

For sulfur hexafluoride (SF6) filled switchgear, new SF6 gas should be in accordance with ASTM D2472 or IEC 60376 [B7]. Reused SF6 gas should be in accordance with IEC 60480 [B8]. For switchgear with SF6 mixtures, refer to IEC 62271-4 [B12].

In order to prevent condensation, the maximum allowable moisture content within gas-filled switchgear filled with gas at rated filling density for insulation ρre shall be such that the dew point is not higher than −5 °C for any measurement during its service life.

7.3 Grounding

Switchgear shall be provided with a reliable grounding point for connection of an equipment ground conductor (EGC) suitable for specified fault conditions. Parts of metallic enclosures connected to the grounding system may be designed to be part of the ground circuit.

All conductive components and enclosures that may be touched during normal operating conditions and are intended to be grounded shall be designed to carry 30 A (dc) with a voltage drop of maximum 3 V to the grounding point provided at the switchgear or, in the case of remotely mounted enclosures, to the grounding point on the enclosure.

NOTE—Some designs of switchgear are remotely mounted, e.g., on a pole, and are intentionally not grounded. The term “Switchgear” as used within this clause includes free-standing circuit breakers (e.g., “outdoor circuit breakers”) and withdrawable circuit breakers when properly installed in their housings as defined by the relevant standards. See IEEE Std C37.20.2 and IEEE Std C37.20.3.

7.4 Auxiliary and control equipment

The functional components required for basic circuit breaker operation and use are listed below. Additional accessory devices may be available and the manufacturer should be consulted.

7.4.1 Electrical controls

Electrical controls shall meet the requirements of IEEE Std C37.11.

7.4.2 Contact position indicator

A reliable mechanical contact position indicator, which can easily be read by the local operator, shall be supplied. The following colors shall be used:

a) Red background with the word “closed” and / or the symbol “|” [see ISO 7000 #5007] in contrasting color to indicate closed contacts.

b) Green background with the word “open” and/ or the symbol “O” [see ISO 7000 #5008] in contrasting color to indicate open contacts.





7.4.3 Operations counter

An operations counter shall be supplied. The preferred arrangement for this device is to operate during the opening cycle of the circuit breaker operation. Counter shall be of the non-resettable type and shall have at least five digits.

7.4.4 Shunt release (trip) device with necessary control auxiliary switches

A shunt release coil with necessary control auxiliary switches shall be capable of tripping the circuit breaker when any voltage throughout the control voltage range is applied. See Table 23 for preferred ratings of control voltages.

7.4.5 Stored energy indicator

A stored energy indicator that can easily be read by the local operator shall be supplied. For stored energy systems using hydraulic fluid or compressed gas, a pressure gauge shall be supplied. The pressure gauge shall clearly indicate sufficient pressure for operation. Systems using stored electrical energy shall provide a visible indication of adequate electrical energy. For stored energy systems using springs, a reliable indicator with the following colors shall be provided:

a) Yellow background with black lettering to indicate “charged” mechanism.

b) White background with black lettering to indicate “discharged” mechanism.

As an alternative to the required stored energy indicator word, a symbol may be used which indicates the stored mechanism is fully charged and discharged.

NOTE—At present there are no uniform symbols to indicate stored energy status, a simple unambiguous graphic should be chosen if utilized.

7.4.6 Manually operated releases

The direction of operation of manual operating handles shall be apparent. Preferred handle operation principles are to

Turn clockwise to close and counter-clockwise to open, or

Push in to close and pull out to open, or

Move right to close and move left to open, or

Move upwards to close and move downwards to open.

Other designs can be implemented.

In the event of failure of the electrical shunt release system (see 7.4.4) circuit breakers shall be equipped with a manually operated release to OPEN the circuit breaker and may optionally be equipped with a manually operated release to CLOSE the circuit breaker. These releases shall be clearly labeled such that an operator can easily identify and operate them. Either or both of these releases may be designated as “Maintenance Only,” (i.e., not suitable for use on energized equipment) in which case it shall be clearly labeled as such. Where circuit breakers are installed in an open enclosure or electrical room a means shall be provided to prevent accidental operation.





Manual releases shall have the following colors:

a) Red background with the word “open” and/or “trip” in contrasting letters to indicate that the release opens the circuit breaker. Optionally, the graphic symbol ‘O’ [see ISO 7000 # 5008] may be used in place of or in addition to the words above.

b) Green or black background with the word “close” in contrasting letters to indicate that the release closes the circuit breaker. Optionally, the graphic symbol ‘I’ [see ISO 7000 # 5007] may be used in place of or in addition to the words “close”.

7.4.7 Functional interlocking components—Drawout circuit breakers

Drawout circuit breakers (i.e. intended for use in enclosures) shall have the necessary position (racking) and mechanism interlocks, primary and secondary disconnects, primary insulation, and control wiring to fully correlate and coordinate with the enclosure standards. See IEEE Std C37.20.2 and IEEE Std C37.20.3 as appropriate.

7.5 Operating mechanisms

Independent manual or power operation (independent unlatched operation) mechanisms are excluded from this standard.

The circuit breaker shall be capable of making and breaking all currents up to its rated values when the energy storage device is suitably charged. Except for slow operation during maintenance, the closed or open position of the main contacts shall not change as a result of loss of the energy supply or the reapplication of the energy supply after a loss of energy to the closing and/or opening device. It shall not be possible for the moving contacts to move from one position to the other, unless the stored energy is sufficient for satisfactory completion of the opening or closing operation.

7.5.1 Dependent power operation

A switching device arranged for dependent power operation with external energy supply shall be capable of making and/or breaking its rated short-circuit current (if any) when the voltage or the pressure of the power supply of the operating device is at the lower of the limits specified under 6.7 (the term “operating device” here embraces intermediate control relays and contactors where provided).

Except for slow operation during maintenance or the operation of a separate undervoltage device or relay, the main contacts shall only move under the action of the drive mechanism and in the designed manner. The closed or open position of the main contacts shall not change as a result of loss of the energy supply or the reapplication of the energy supply after a loss of energy, to the closing and/or opening device.

7.5.2 Stored energy operation

7.5.2.1 General

A switching device arranged for stored energy operation shall be capable of making and breaking all currents up to its rated values when the energy storage device is suitably charged. Except for slow operation during maintenance, the main contacts shall only move under the action of the drive mechanism and in the designed manner, and not in the case of re-application of the energy supply to the energy storage device after a loss of energy.

A device indicating when the energy storage device is charged shall be mounted on the switching device, see 7.4.5.





It shall not be possible for the moving contacts to move from one position to the other, unless the stored energy is sufficient for satisfactory completion of the opening or closing operation. Stored energy systems for both opening and closing shall be capable of being discharged, restrained or otherwise reduced to a condition consistent with personnel safety during maintenance operations by properly trained personnel.

7.5.2.2 Stored energy requirements for operating mechanisms

Operating mechanism stored energy requirements depend on time to recharge after a CO (close-open) operation of the circuit breaker. Mechanism recharging requirements given in Table 25 are the maximum permissible recharging times for recharging the operating mechanism to restore rated conditions of energy storage (i.e., spring charge, pneumatic pressure, hydraulic pressure, capacitor or other energy storage method) after one CO operation starting at rated conditions. Rated control voltages shall be used in determining the recharge time.

Table 25 —Energy storage requirements of operating mechanisms

Maximum recharging time after CO operation Stored energy requirements

30 s Two CO a 30 min Four CO Over 30 min Five CO

a CO = close-open When the opening of a circuit breaker is dependent on stored energy in the form of pressured gas, fluid or stored electrical energy, and that capability is inadequate both closing and opening operations of that circuit breaker shall be prevented. A means shall be provided to initiate an alarm before the function becomes inoperative.

7.5.2.3 Energy storage in gas receivers or hydraulic accumulators

When the energy storage device is a gas receiver or hydraulic accumulator, the requirements of 7.5.2 apply at operating pressures between the limits specified in items a) and b).

a) External pneumatic or hydraulic supply.

b) Unless otherwise specified by the manufacturer, the limits of the operating pressure are 85% and 110% of their specified rated pressure.

c) Higher limits may apply where receivers also store compressed gas for interruption. The applicable equipment standard should address as needed the maximum limit if applicable.

d) Compressor or pump integral with the switching device or the operating device.

e) The limits of operating pressure shall be stated by the manufacturer.

7.5.2.4 Energy storage in springs (or weights)

When the energy storage device is a spring (or weight), the requirements of 7.5.2.1 apply when the spring is charged (or the weight lifted).

7.5.2.5 Manual charging

If a spring (or weight) is charged by hand, the direction of motion of the handle shall be marked.





The manual charging facility shall be designed such that the handle is not driven by the operation of the switching device.

The maximum actuating force required for manually charging a spring (or weight) shall not exceed 250 N (56 lbf).

7.5.2.6 Motor charging

Motors, and their electrically operated auxiliary equipment for charging a spring (or weight) or for driving a compressor or pump, shall operate satisfactorily within the limits of the voltages shown in Table 23, the frequency, in the case of ac, being the rated supply frequency.

NOTE—For electric motors, the limits do not imply the use of non-standard motors but only the selection of a motor which at these values provides the necessary effort, and the rated voltage of the motor need not coincide with the rated supply voltage of the closing device.

7.5.2.7 Energy storage in capacitors

When the energy storage is a charged capacitor, the requirements of 7.5.2.1 apply when the capacitor is charged except that indication of the charged state may be placed on the energy storage device rather than the switching device.

7.5.3 Trip-free requirements

The circuit breaker operating mechanism(s) shall be designed so that the tripping function shall prevail over the closing function. When a tripping signal (mechanical or electrical) is received while a closing operation is being executed, even if the closing signal (mechanical or electrical) is maintained, the following shall apply:

a) If the closing signal is applied simultaneously with the tripping signal (mechanical or electrical) or if the tripping signal is applied after the closing signal, the circuit breaker contacts shall be permitted to close or touch momentarily.

b) If the tripping circuit is completed through the circuit breaker auxiliary switch contact(s) (or other electrical devices), electrical tripping devices will not be energized until after the auxiliary switch contacts have closed and the circuit breaker main contacts are permitted to close or touch momentarily.

c) If the mechanical tripping signal is applied and held prior to the application of a closing signal (mechanical or electrical), the circuit breaker contacts shall not be permitted to close, even momentarily. It may be necessary for the mechanism to release energy during such an operation. However, movement of the contacts shall not reduce the open gap by more than 10%, nor shall it reduce the rated insulation capability for the contact gap, and the contacts shall come to rest in the fully open position.

7.5.4 Anti-pump function

The anti-pump function, shall be provided as required in IEEE Std C37.11.

7.5.5 Frequency of operation

Operating mechanism components shall be capable of up to 30 CO operations per hour provided rated control voltage is available to energy storage system. This requirement refers to the operating mechanism capability and is independent of the making / breaking capability of the interrupting assemblies. Where the





energy storage and recharging time (see Table 25) do not permit continuous operation at this rate, the mechanism shall be capable of this rate of operations following recharging of the stored energy system.

7.5.6 Maintenance provisions

a) If required for maintenance of the circuit breaker, a means of manual operation during maintenance shall be provided.

b) Means shall be provided to prevent automatic operation of the mechanism when maintenance work is being performed.

c) Means shall be provided to remove accumulated moisture or other foreign liquids from compressed gas receivers.

d) Electronic and electro-mechanical controllers, relays, solenoids, motors and similar items required for proper operation of the circuit breaker mechanism shall be field replaceable. Additionally, energy storage components with a service life less than the expected service life of the circuit breaker (e.g., typical electrolytic energy storage capacitors) shall also be field replaceable.

e) Stored energy systems for both opening and closing shall be capable of being discharged, restrained, or otherwise reduced to a condition consistent with personnel safety during maintenance operations by properly trained personnel.

7.6 Alternative operating mechanisms

An alternative operating mechanism is obtained when a change in the power kinematic chain of the original operating mechanism or the use of an entirely different operating mechanism leads to the same mechanical characteristics of the interrupting assembly. It is not necessary that the two operating mechanisms share the same operating principles, for example one mechanism may be spring and the other hydraulic.

To establish that one operating mechanism (the alternative operating mechanism) has the same mechanical characteristics as the fully type tested mechanism (original operating mechanism) the travel-time curves of the two mechanisms at rated voltage or operating pressure must be compared.

a) The travel- time curve of the original operating mechanism that was obtained at the beginning of the make and break testing is the ‘reference curve’.

b) The travel-time curve of the prospective alternative operating mechanism shall be obtained under conditions matching those of the reference curve.

c) From the reference curve, obtained in a) two envelope curves shall be drawn from the instant of contact separation to the end of the contact travel for the opening operation and from the beginning of the contact travel to the instant of contact touch for the closing operation. The distance of the two envelopes from the original course shall be ±5% of the total stroke. In case of circuit breakers with a total stroke of 40 mm or less the distance of the two envelopes from the original course shall be ±2 mm. It is recognized that for some designs of circuit breakers, these methods may be unsuitable, as for example for vacuum circuit breakers or for some circuit breakers rated less than 52 kV. In such cases the manufacturer shall define an appropriate method to verify the proper operation of the circuit breaker.

d) The envelopes can be moved in the vertical direction until one of the curves covers the reference curve. This gives maximum tolerances over the mechanical characteristics of –0%, +10% and –10%, +0%, respectively for the opening curve and the closing curve considered independently. The displacement of the envelope can be used only once for the complete procedure in each test (once for opening and once, but perhaps with another direction or magnitude for closing) in order to get a maximum total deviation from the reference characteristic of 10%.





e) In circuit breakers with interrupting assemblies incorporating non-sliding contacts (or similar contacts) in which weld breaking forces are a consideration, the capabilities of the alternative mechanism to satisfy the short-time and peak withstand duties shall be demonstrated.

Provided that the criteria above are met, the alternative operating mechanism is considered to have the same mechanical characteristics as the original, fully type tested, mechanism and a limited testing sequence, as defined in IEEE Std C37.09 for alternative operating mechanisms may be used.

7.7 Low- and high-pressure interlocking and monitoring devices

7.7.1 Gas pressure

Closed pressure systems filled with compressed gas for insulation and/or operation and having a minimum functional pressure for insulation and/or operation above 0.2 MPa (absolute pressure) shall be provided with a device to check the pressure (or density).

The uncertainty of the gas monitoring device should be established and take into account the pressure coordination (filling, minimum functional and alarm pressure) and leakage rate.

7.7.2 Liquid level

A device for checking the liquid level, with indication of minimum and maximum limits permissible for correct operation, shall be provided. This is not applicable to dash-pots or shock-absorbers.

7.8 Degrees of protection by enclosures

7.8.1 General

The degrees of protection provided by enclosures shall be in accordance with ANSI/IEC 60529 and 7.8.2 through 7.8.4.

7.8.2 Protection of persons against access to hazardous parts and protection of the equipment against ingress of solid foreign objects (IP coding)

The degree of protection of persons provided by an enclosure against access to hazardous parts of the main circuit, control, and/or auxiliary circuits and to any hazardous moving parts shall be at least IP2X according to ANSI/IEC 60529.

7.8.3 Protection against ingress of water (IP coding)

For equipment of indoor installation, no minimum degree of protection against harmful ingress of water is specified, i.e., the second characteristic numeral of the IP code is X according to ANSI/IEC 60529.

Equipment for outdoor installation in secure areas shall be at least IPX3 according to ANSI/IEC 60529. If it is provided with additional protection features against rain and other weather conditions (supplementary letter W), the performance refers to the situation with these features in place and shall be demonstrated according to IEEE Std C37.100.1-2007™, Annex F.





7.8.4 Protection of equipment against mechanical impact under normal service conditions (IK coding)

If protection of equipment against mechanical impact is required, the IK coding according to IEC 62262 [B10] should be followed.

7.9 Enclosure and wiring requirements

7.9.1 Operating mechanism enclosure

The operating mechanism for outdoor circuit breakers shall be mounted and enclosed in weatherproof enclosure with door(s) so arranged as to make accessible parts of the mechanism usually requiring inspection or maintenance. Each enclosure shall have a removable conduit plate or sufficient conduit knockouts for bringing in conduit.

7.9.2 Enclosure wiring

The wiring for all control devices shall be included and shall terminate on readily accessible terminal blocks in reasonable proximity to incoming conduit.

7.9.3 Condensation

To reduce condensation, each outdoor enclosure shall have a continuous or thermostatically controlled heater. Indoor circuit breakers should consider the use of heaters to reduce condensation or rust in unconditioned or unheated areas.

7.9.4 Wiring for instrument current and voltage transformers

Wire for current transformer secondary leads shall not be smaller than 14 AWG. Wire for voltage transformer secondary leads and for control wiring shall be electrically coordinated with the inherent current requirements and voltage drop limitations of the circuit, and mechanically coordinated and designed for its intended application in the circuit breaker. Splices, when required, shall be brazed or made by permanently fitted pressure type connectors.

7.10 Creepage distances

The creepage distance over external insulation for outdoor circuit breakers is listed in Table 6. These minimum values are for light pollution level conditions of atmospheric contamination as defined by 4.2.3 and Annex C. For special cases of pollution, refer to IEEE Std C37.010.

7.11 Gas and vacuum tightness

7.11.1 Closed pressure systems for gas

A closed pressure system for gas is a volume that can be replenished only periodically by manual connection to an external gas source. The tightness characteristic of a closed pressure system stated by the manufacturers shall be consistent with a minimum maintenance and inspection philosophy. The maximum leakage rate for a circuit breaker in a high switching operation for a closed pressure system for gas shall be less than 1% per year. The alternate preferred leakage rates are 0.5% and 0.1% per year.





7.11.2 Sealed pressure systems

A sealed pressure system is a volume for which no further gas or vacuum processing is required during the expected operating life.

7.12 Liquid tightness

7.12.1 General

The following specifications apply to all switchgear that use liquids as insulating, or combined insulating and interrupting, or control medium with or without permanent pressure.

7.12.2 Leakage rates

The permissible leakage rate for liquid Fp(liq) shall be indicated by the manufacturer. A clear distinction shall be made between internal and external tightness where internal tightness refers to leakage between two compartments within a single closed system and external tightness refers to leakage outside of the closed system.

a) Total tightness: no liquid loss can be detected.

b) Relative tightness: slight loss is acceptable under the following conditions:

1) The leakage rate, F(liq), shall be less than the permissible leakage rate, Fp(liq).

2) The leakage rate, F(liq), shall not continuously increase with time or in the case of switching devices, with number of operations.

3) The liquid leakage shall cause no malfunction of the switchgear, nor cause any injury to operators in the normal course of their duty.

7.13 Noise requirements

The purpose of this clause is to establish guidelines to provide protection against excessive environmental disturbance from outdoor switchyard circuit breakers. This clause does not apply to circuit breakers used in gas insulated substations and metal enclosed equipment.

Outdoor circuit breakers shall be designed to comply with the noise regulations that set forth measurements and practices with regard to noise levels that are deemed acceptable in occupational environments without personal protective equipment to reduce the noise level.

Design tests to verify compliance with this clause are not required for most modern outdoor circuit breakers, as the noise levels are quite low compared to historic designs. If tests are required to verify compliance, refer to IEEE Std C37.09 for requirements.

7.13.1 Noise exposure conditions

Noise exposure conditions cover the exposure under the following circumstances:

a) Personnel at, or very close to, the circuit breaker during installation, maintenance, or inspection periods

b) Personnel at control stations

c) Persons in the proximity of the equipment as permitted by limiting boundaries





7.13.2 Noise level

The noise level for outdoor circuit breakers shall not exceed those values given in Table 26 for the different equipment and noise classifications. Where intermittent noise recurs several times daily, with each noise level persisting for 1 s or as long as several hours per day, the accumulated intermittent noise shall be calculated as follows, using the permissible sound levels and times given in Table 27.

Table 26 —Sound pressure level limits

Equipment classification

(kV) Range

Impulse noise limit Intermittent noise limit Continuous noise limit e Maximum

sound pressure

level (dB)a

Horizontal distance to

measurement point, m (ft)

Maximum sound

pressure level (dB)a



Maximum sound

pressure level (dB)a



General-purpose outdoor equipment

362 kV and below 140 1 (3) b d 15 (50) b 90 15 (50) b

Above 362 kV 140 1 (3) b

0.7 (2) c d 30 (100) b 90 30 (100) b

Definite-purpose outdoor equipment (These limits are in addition to those required for general-purpose outdoor equipment

362 kV and below 105 95

50 (150) b

150 (500) b 90 80

50 (150) b

150 (500) b 85 75

50 (150) b

150 (500) b

Above 362 kV 105 95

100 (300) b

300 (1000) b 90 80

100 (300) b

300 (1000) b 85 75

100 (300) b

300 (1000) b a The sound level limits are based on no-load operation since personnel are not expected to stand adjacent to the circuit

breaker when it is opening under fault conditions. Measurement shall be made 1.5 m (5 ft) above ground level. b Measured from perimeter of circuit breaker with cabinet doors closed. c Measured at location of the control switch of the circuit breaker with the cabinet doors open. d See 7.13.2 for maximum allowable sound level. e It is considered that the routine operation of the switching station will not submit a person to continuous or

intermittent exposure unless the operator is at least at or within the specified minimum distance from the noise, depending on the circuit breaker voltage rating.

Table 27 —Permissible noise exposure a

Duration per day, hours (Ti)

Sound level, dBA

8 90 6 92 4 95 3 97 2 100

1-1/2 102 1 105 ½ 110

1/4 or less 115 a Care shall be taken so that measurements will not be influenced by noise reflection, focus, or amplification from walls, buildings, or other surfaces.

When the daily noise exposure is composed of two or more periods of exposure to different sound levels, their combined effect shall be considered, rather than the individual effect of each. If the sum of the following fractions: C1/T1 + C2/T2 ...+ Cn/Tn exceeds unity, then the mixed exposure shall be considered





to exceed the limit value. Cn indicates the total time of exposure at a specified sound level, and Tn indicates the total time of exposure permitted at that level. If the period between repeating (intermittent) noise is less than 1 s, the noise is considered to be continuous. Exposure to impulsive or impact noise shall not exceed 140 dB peak sound pressure level.

For indoor circuit breakers not used in metal enclosed equipment, or the mechanism of outdoor circuit breakers, a sound level measurement shall be made at 0.9 m (3 ft) from the mechanism with the door open (if equipped), with measured background noise not exceeding 65 dBA. The measurement shall be recorded and made available to the end users. The value of 140 dB is the OSHA limit for the typical operating time of a circuit breaker for one working day

7.14 Electromagnetic compatibility (EMC)

Switchgear shall be capable of satisfying the EMC tests specified in IEEE Std C37.09.

The secondary system shall be able to withstand transient voltage disturbances up to 1500 V without damage or malfunction. This applies to normal operation and under switching conditions, including interruption of fault currents in the main circuit. The secondary system consists of the following:

a) Control and auxiliary circuits, including circuits in control cubicles;

b) Equipment for monitoring, diagnostics, etc., that is part of the circuit breaker;

c) Circuits connected to the secondary terminals of instrument transformers.

7.15 Vacuum interrupters and X-Ray emission

Vacuum interrupters used in high voltage circuit breakers shall comply with the requirements of ANSI C37.85.

7.16 Radio influence voltage limits

Radio influence voltage limits given in Table 28 apply for circuit breakers rated 123 kV and above. For lower voltage ratings, the radio influence voltage is relatively low, and radio interference effects negligible. Radio influence voltage tests, if required, shall be conducted in accordance with IEEE Std C37.09 and NEMA 107.

Table 28 —Limits of radio influence voltage a, b, c, d

Circuit breaker rated maximum voltage

(kV)

Test voltage (kV)

Limit of radio influence voltage (µV) at 1000 kHz

15.5 9.4 500 25.8 15.7 650 38.0 23 650 48.3 29 1250 72.5 44 1250 123 78 2500 145 92 2500 170 108 2500 245 156 2500

a Measurements shall be made with circuit breakers in the non-current-carrying or non-operating condition. b In the case of circuit breakers having voltage ratings not covered by this table, the test voltage shall be 10% above

the line-to-neutral voltage corresponding to the maximum voltage of Range B as given in ANSI C84.1. c Circuit breakers having two voltage ratings shall be tested at the higher voltage rating. d RIV limits for rated voltages below 123 kV are listed for historical reference only.





7.17 Requirements for terminals and bushings used on outdoor or free standing circuit breakers

7.17.1 Bushings

Bushings for use in high voltage circuit breakers shall be in accordance with IEEE Std C37.017.

7.17.2 Threaded terminal dimensional requirements

The thread dimensions for threaded terminal studs for circuit breakers shall be in accordance with Table 29.

Table 29 —Thread dimensions for threaded terminal studs

Unified basic thread size

(in) Threads per inch Thread Class

Minimum length Length of stud

in (mm) Usable thread

in (mm) 3/4 16 UNF-2A 2 (50) 1-1/2 (38)

1-1/8 12 UNF-2A 2-1/2 (63) 2-1/8 (53) 1-1/4 12 UNF-2A 2-1/2 (63) 2-1/8 (53) 1-1/2 12 UNF-2A 2-1/2 (63) 2-1/8 (53) 1-3/4 12 UN-2A 2-1/2 (63) 2-1/8 (53)

2 12 UN-2A 3 (76) 2-1/2 (63) 2-1/2 12 UN-2A 3 (76) 2-1/2 (63)

7.17.3 Flat terminals

Flat terminal requirements shall be in accordance with NEMA CC1, figures C-2 to C-6. Bolt holes shall be 14 mm (9/16 in) in diameter.

7.17.4 Ground terminals

The preferred ground terminals for outdoor circuit breakers shall be unpainted, copper faced steel, or stainless steel pad, 51 mm by 89 mm (2 in by 3.5 in) minimum area for terminal connection. The terminal area shall be provided with two holes spaced on 45 mm (1.75 in) centers. The holes shall either be 14 mm (9/16 in) diameter through-holes, or drilled and tapped for a 1/2 in 13 NC thread and shall have a minimum thread depth of 13 mm (0.5 in). If through-holes are provided, the pad shall have a thickness calculated to be able to carry the rated fault current for a minimum of 2 s without annealing1. Absent any fault current specific calculation a thickness of 6 mm (1/4 in) is sufficient. Equivalent sized ground pads are allowed if conductivity, surfacing, and mating parts are equal to the preferred connection and meet the requirements of the application.

The grounding provisions for circuit breakers used in metal-enclosed assemblies shall be in accordance with the requirements of the standards applicable to the metal-enclosed switchgear assembly.

7.18 Circuit breaker mechanical loading

This subclause applies to outdoor circuit breakers. For indoor circuit breakers in metal-enclosed switchgear, the seismic or mechanical requirements of IEEE Std C37.20.2 and IEEE Std C37.20.3 apply.

1 Annex E of IEEE Std C37.30.1-2011 [[B30] provides one such calculation. Other authoritative sources may be utilized.





The maximum permissible mechanical loading that may be applied to a circuit breaker is as described in 7.18.1 through 7.18.4. All other mechanical loading is considered special, and application shall be checked with the manufacturer.

7.18.1 Wind loading

The circuit breaker shall be capable of withstanding a wind speed of 40 m/s (120 ft/s). This requirement is only applicable to outdoor circuit breakers.

7.18.2 Ice loading

The circuit breaker shall be capable of withstanding ice loading caused by up to 20 mm (0.75 in) of ice. This requirement is only applicable to outdoor circuit breakers.

7.18.3 Seismic loading

All circuit breakers shall be capable of withstanding at least 0.2 times the equipment weight applied in one horizontal direction, combined with 0.16 times the weight applied in the vertical direction at the center of gravity of the circuit breaker and support structure. The resultant load shall be combined with the maximum normal operating load to develop the greatest stress on the anchorage.

For guidance in the application of circuit breakers, where the seismic conditions exceed those described here, refer to IEEE Std C37.010 and IEEE Std 693 [B21].

7.18.4 Terminal loading

The maximum permissible terminal mechanical loading that may be applied to an outdoor circuit breaker is given as static forces in Table 30 (see Figure 11). All other terminal loading in excess of these values is considered special, and application shall be checked with the manufacturer. The user shall consider all forces acting on the conductors connected to the terminals. These forces include: wind, ice, seismic, and short-circuit forces.

Table 30 —Terminal mechanical loading

Rated maximum voltage

Rated continuous current

Static horizontal force Static vertical force a

Longitudinal (N) Transverse (N) Vertical (N) Below 100 kV 1200 A and below

Above 1200 A 500 750

400 500

500 750

123 kV to 170 kV 2000 A and below Above 2000 A

1000 1250

750 750

750 1000

245 kV All 1250 1000 1250 362 kV to 800 kV All 1750 1250 1250

aVertical axis forces are upward and downward.





Figure 11— Static Forces

7.19 Pressurized components

7.19.1 Non-Isolating vessels

All non-isolating (conductive) vessels, except those having internal or external operating gas pressure not exceeding 207 kPa (absolute) (30 psia), with no limitation on size, or those having an inside diameter not exceeding 152 mm (6 in) (with no limitation on pressure), shall be designed and tested in accordance with the ASME Boiler and Pressure Vessel Code, Section VIII, Pressure Vessels, and any state and local codes that apply at the point of original installation.

7.19.2 Isolating vessels and components

All isolating pressurized vessels, insulators, and tubes which have an internal-to-external or external- to-internal differential gas pressure exceeding 207 kPa (absolute) (15 psig); and have an inside diameter exceeding 152 mm (6 in); shall be individually tested as indicated in IEEE Std C37.09.

7.20 Pressurized systems

Each gas system on a circuit breaker shall have an ASME-approved pressure relief device set to operate to relieve pressure at a value not exceeding the maximum allowable working pressure of the system. Such valve shall be designed to prevent the pressure from rising more than 20% above the maximum allowable working pressure.

If a gas system that includes pressurized porcelains, epoxies, or other brittle materials is subjected to substantial rates-of-rise of pressure caused by exposure to abnormal events or sources of heat, additional overpressure relief set at 20% above maximum allowable working pressure shall be provided by one of the following or its equivalent:

a) Rupture diaphragm

b) Large area relief piston

c) Spring-clamped construction

d) Design for controlled rupturing

When a pressurized metal vessel of an interconnected system of metal and porcelain elements is provided with a device qualifying under the above, this device may be used to protect the interconnected system. Any porcelain, epoxy, or other brittle materials that are pressurized shall be protected by the overpressure relief device.





Exception:

By agreement between the user and the manufacturer, the requirement for an ASME-approved pressure relief device may be exempted for closed gas systems that have a gas volume sufficiently large so as to limit the gas pressure rise to less than 1.5 times the design pressure in the event of an uncontrolled arc for a time period limited by relay operation.

7.21 Requirements for simultaneity of poles

When no special requirements with respect to simultaneous operation of poles is stated, the maximum difference between the instants of contacts touching during closing shall not exceed 1/4 of a cycle of rated power frequency.

When no special requirement with respect to simultaneous operation of poles is stated, the maximum difference between the instants of contacts separating during opening shall not exceed 1/6 of a cycle of rated power frequency. Circuit breakers with an intentional delay between poles need special consideration. Circuit breakers with operations after a single-pole operation are not subject to these requirements.

8. Nameplate markings

8.1 Circuit breaker

Circuit breaker and operating mechanism nameplates may be combined.

a) Manufacturer’s name

b) Manufacturer’s type designation

c) Manufacturer’s serial number

d) Year of manufacture

e) Rated maximum voltage

f) Rated power frequency

g) Rated continuous current

h) Rated full wave lightning impulse withstand voltage

i) Rated switching-impulse withstand voltages (if applicable)

1) Terminal-to-ground circuit breaker closed

2) Terminal-to-terminal circuit breaker open

j) Rated operating duty cycle

k) Rated interrupting time

l) Rated short-circuit current

m) Percent dc component

n) Short time current duration

o) Normal operating pressure; (if applicable)

p) Minimum operating pressure; (if applicable)

q) Volume of oil per tank or weight of gas per circuit breaker; (if applicable)





r) Weight of circuit breaker complete (with oil or gas)

s) Instruction book number

t) Parts list number; (if different from instruction book number)

u) Capacitive current switching class (i.e., C0, C1, C2) and rating (as applicable)

1) Rated overhead line switching current

2) Rated cable charging current

3) Rated isolated shunt capacitor bank switching current

4) Rated back-to-back capacitor bank switching current

5) Rated back-to-back capacitor bank transient peak inrush making current

6) Tested back-to-back capacitor bank inrush making frequency

v) Rated out-of-phase switching current. (if applicable)

8.2 External insulation

The rated insulation capability of the external insulation shall be included on the circuit breaker nameplate, except when it is a self-contained component, such as a bushing or current transformer; then it shall be included on the nameplates of the component (see IEEE Std C37.017 for bushings).

8.3 Operating mechanism

Operating mechanism and circuit breaker nameplates may be combined.





e) Closing control voltage range

f) Tripping control voltage range

g) Closing current

h) Tripping current

i) Compressor or hydraulic pump or spring charging motor control voltage range

j) Compressor or hydraulic pump or spring charging motor current, and if applicable limitations on mechanism operating frequency less than 30 CO per hour (see 7.5.5)

k) Compressor or hydraulic pump control switch closing and opening pressure (if applicable)

l) Low-pressure alarm switch closing and opening pressure (if applicable)

m) Low-pressure lockout switch closing and opening pressure (if applicable)

n) Wiring diagram number

o) Instruction book number

p) Parts list number. (if different from instruction book number)

q) Mechanism endurance class M1 or M2 shall be marked as applicable





8.4 Current transformer and linear coupler nameplates

This subclause defines requirements for nameplates for current transformers used on or with live tank circuit breakers. Current transformers mounted internally on dead tank circuit breakers shall be supplied with a nameplate conforming to the requirements of IEEE Std C57.13.

Current transformer and linear coupler nameplates shall be provided that contain the following data, as applicable. This information shall be provided in an area convenient to the respective terminal blocks. This requirement is in addition to the nameplate required by IEEE Std C57.13 on the current transformer itself.





e) Rated frequency

f) Rated maximum voltage

g) Rated impulse withstand voltage

h) Rated power frequency withstand voltage

i) Rated switching impulse withstand voltage

j) Rated primary current

k) Rated secondary current

l) Rated continuous thermal current factor at specified average ambient temperature

m) Rated thermal short time current

n) Rated mechanical short time current

o) Weight of complete current transformer

p) Gallons of oil or weight of gas per current transformer

q) Instruction book number

r) A connection diagram showing full winding development, and including:

1) The primary terminal markings 2) The position of each secondary core 3) The terminal designation of each core 4) The polarity markings of the primary and each core 5) The turns ratio between each terminal 6) The full winding ratio expressed, for example, as 3000:5 MR 7) The accuracy class of each core and the ratio for which the accuracy is expressed

s) Accuracy curve identification

t) Mutual reactance (for linear coupler transformers only)

u) Self-impedance (for linear coupler transformers only)

1) Resistance 2) Reactance 3) Impedance





8.5 Accessories

Nameplates of all accessories shall include the following:

a) Identification

b) Pertinent operating characteristics

8.6 Instructions and warning signs

Essential markings shall be provided to:

Identify operating devices and positions

Give pertinent instructions for operation

Call attention to special precautions

Call attention to environmental warnings

9. Current transformers

9.1 General

The requirements of this clause supplement the basic requirements of IEEE Std C57.13, to cover those requirements peculiar to current transformers used on or with outdoor circuit breakers. The requirements of this clause do not apply to current transformers provided in metal-enclosed switchgear assemblies.

9.1.1 Terminology

The ratings of a current transformers used on or with outdoor high voltage circuit breakers shall include those terms used in IEEE Std C57.13 and the following additional terms:

a) Maximum voltage

b) Dielectric withstand

c) Thermal short time current capability

9.2 Ratings

9.2.1 Continuous thermal current capability

The continuous thermal current capability of a current transformer shall be equal to the rated continuous current of the outdoor circuit breaker with which it is used when connected on a ratio having a primary current rating equal to or greater than the continuous current rating of the circuit breaker.

Exception:

If connection is made on a lower ratio, the circuit breaker can carry a current equal to the primary current of that ratio including the thermal factor without causing overheating of the current transformer.





9.2.2 Mechanical short-time current capability

The mechanical short time current capability of any tap of a single ratio or multi-ratio current transformer shall be the lesser symmetrical current value of either (1) 120 times the rated primary current of the tap under consideration or (2) the closing and latching capability of the circuit breaker as required by 5.6.2.3.

Exception:

Where item (1) is the lower value, the effects of the power system parameters, secondary burden, and thermal short time current capability shall be considered in the application of current transformers.

9.2.3 Thermal short-time current capability

The thermal short time current capability of a single ratio transformer or any tap of a multi-ratio current transformer shall be the lesser symmetrical current value of either (1) 60 times the rated primary current of the tap under consideration for 1 s, (2) 42.5 times the rated primary current of the tap under consideration for 2 s, or (3) the short time current carrying capability of the circuit breaker in accordance with 5.6.2.3.

9.2.4 Accuracy class rating

The accuracy class ratings of current transformers used on or with outdoor circuit breakers shall be as shown in Table 31.

Table 31 —Accuracy class ratings for current transformers used on or with class S2 circuit breakers

Circuit breaker ratings Accuracy class ratings a

Maximum voltage, kV, rms

Continuous current 60 Hz amperes, rms

Relaying service Metering service Multi-ratio

current transformers b

Accuracy class c

Single-ratio current

transformers d

Accuracy class e

15.5 through

48.3

600 800 1200 2000 3000 4000 5000

600:5 1200:5 2000:5 3000:5 4000:5 5000:5

100 200 400 800

300:5 600:5 800:5

1200:5 1500:5 2000:5 3000:5

0.6B--0.5 0.6B--0.5 0.6B--0.5 0.3B--0.5 0.3B--0.5 0.3B--0.5 0.3B--0.5

72.5 1200 2000

1200:5 2000:5 3000:5

400 800

123 and above 1200 1600 2000 3000 4000

1200:5 2000:5 3000:5 4000:5 5000:5

800

a These values apply only when current transformers are used on 60 Hz circuits. b These current transformers normally have a primary current rating that corresponds to the continuous current rating of the circuit breaker, except that circuit breakers rated 800 and 1600 amperes use current transformers rated 1200 and 2000 amperes, respectively. c These secondary terminal voltage values for C or T classifications apply to the full winding as specified in IEEE Std C57.13 for 10 percent error. d Minimum ratios shall not be less than 50 percent of the continuous current rating of the circuit breaker. e These values apply only to those secondary windings specified for metering service.





9.3 Polarity and lead marking

Polarity and lead marking shall be as shown in IEEE Std C57.13 and in accordance with the following additional requirements.

9.3.1 Bushing type current transformers

Polarity and lead marking for bushing type current transformers shall be as shown in Figure 12, Figure 13, and Figure 14. The two leads for single ratio current transformers such as those used for metering service shall be marked X1 and X2.

Figure 12—Typical CT bushing diagram

Typical arrangement of two bushing-type current transformers on one pole of dead-tank-type circuit breakers. When intermediate taps are used, the tap numerically nearest X1 has the same polarity as X1.





Figure 13—Current transformer and lead identification of bushing-type current transformers for dead-tank type circuit breakers

Exact location of current transformers, leads, polarity marks, and terminal blocks shall be shown on manufacturer’s connection diagram or instructions. When one current transformer per pole is used, current transformers are located on primary terminals 1-3-5 unless otherwise specified.





Figure 14—Current transformer and lead identification of current transformers for live-tank type circuit breakers

Exact location of current transformers, leads, polarity marks, and terminal blocks shall be determined from the manufacturer’s connection diagram or instructions.

9.3.2 Secondary leads and terminations

Secondary leads shall be brought out to accessible terminal boards with polarity, phase, and lead designations shown on suitable connection diagrams. Terminal boards shall be equipped with means for short circuiting individual secondaries. Where applicable, secondary leads shall be brought out through suitable oil and gas tight seals.

9.3.3 Typical connection for secondary burdens

Typical connection for secondary burdens to bushing type current transformers shall be as shown in Figure 15, Figure 16, Figure 17, and Figure 18. Similar connections shall be made for the various secondaries of free standing current transformers, except that all four secondaries shall be on the same side of the circuit breaker.





Figure 15—Typical connection of secondary burdens with one current transformer per circuit pole

Figure 16—Typical connection of secondary burdens with two current transformers per circuit breaker connected independently

Figure 17—Connection of secondary burdens with two current transformers per circuit breaker pole connection in series used when burdens are large





Figure 18—Connection of secondary burdens with four current transformers per circuit breaker pole two per terminal connected independently and

two per terminal connection in series

9.4 Undervoltage trip device

An undervoltage device trip is a device in which the coil is energized without an auxiliary switch. The armature may be released for tripping when the voltage applied to it drops to a value that falls within the specified dropout voltage range.

If provided, an under-voltage release shall operate to open the switching device when the voltage at the terminals of the release falls below 30% of its rated voltage, even if the fall is slow and gradual.

Between 70% and 30% of its rated supply voltage, the under-voltage release may operate to open the switching device or may operate to permit closing of the switching device.

The under-voltage release shall not operate to open the switching device when the voltage at its terminals exceeds 70% of its rated supply voltage.

The closing of the switching device shall be possible when the value of the voltage at the terminals of the release is equal to or greater than 85% of its rated voltage.

The under-voltage release shall prevent closing of the switching device when the voltage at the terminals of the under-voltage release is below 30% of its rated supply voltage.

9.5 Specialized Applications

Specialized applications should be referred to the manufacturer. Arc furnace switching is such a specialized application. The requirements for circuit breakers intended for switching of arc furnace transformers are contained in Annex D.





Annex A

(informative)

Bibliography

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[B16] IEC/TR 60943 Technical Report Guidance concerning the permissible temperature rise for parts of electrical equipment, in particular for terminals.

[B17] IEC/TR 62271-300 Technical Report High Voltage Switchgear and Controlgear—Part 300: Seismic qualification of alternating current circuit breakers.

[B18] IEC/TR 62271-306 Technical Report High Voltage Switchgear and Controlgear—Part 306: Guide to IEC 62271-100, IEC 62271-1 and other IEC standards related to alternating current circuit breakers.

[B19] IEC/TS 62271-210, High-Voltage Switchgear and Controlgear—Part 210: Seismic qualification for metal enclosed and solid-insulation enclosed switchgear and controlgear assemblies for rated voltages above 1 kV and up to and including 52 kV.





[B20] IEEE Std 1™, IEEE Recommended Practice - General Principles for Temperature Limits in the Rating of Electric Equipment and for the Evaluation of Electrical Insulation.

[B21] IEEE Std 693™, IEEE Recommended Practices for Seismic Design of Substations.

[B22] IEEE 1313.2™-1999, IEEE Guide for the Application of Insulation Coordination.

[B23] IEEE Std C37.04™-1999, IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers.

[B24] IEEE Std C37.06™-2009, IEEE Standard for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis—Preferred Ratings and Related Required Capabilities for Voltages Above 1000 V.

[B25] IEEE Std C37.06.1™, Recommended Practice for Preferred Ratings for High-Voltage (>1000 volts) AC Circuit Breakers Designated Definite Purpose for Fast Transient Recovery Voltage Rise Times.

[B26] IEEE Std C37.011™, Guide for the Application of Transient Recovery Voltage for AC High-Voltage Circuit Breakers with Rated Maximum Voltage above 1000 V.

[B27] IEEE Std C37.012™, IEEE Guide for the Application of Capacitance Current Switching for AC High-Voltage Circuit Breakers above 1000 V.

[B28] IEEE Std C37.015™, IEEE Guide for the Application of Shunt Reactor Switching.

[B29] IEEE Std C37.24™, IEEE Guide for Evaluating the Effect of Solar Radiation on Outdoor Metal-Enclosed Switchgear.

[B30] IEEE Std C37.30.1™-2011, IEEE Standard Requirements for AC High-Voltage Air Switches Rated Above 1000 V.

[B31] IEEE Std C37.30.2™, IEEE Guide for Wind-Loading Evaluation of High-Voltage (>1000 V) Air-Break Switches.

[B32] IEEE Std C37.81™, IEEE Guide for Seismic Qualification for Class 1E Metal-Enclosed Power Switchgear Assemblies.

[B33] Pons, A., Sabot, A., Babusci, G., “Electrical endurance and reliability of circuit breakers. Common experience and practice of two utilities,” IEEE Transactions on Power Delivery, vol 8, no. 1, pp 168–174, Jan. 1993.

[B34] Steurer, M., Hribernik, W., and Brunke, J. H., “Calculating the transient recovery voltage associated with clearing transformer determined faults by means of frequency response analysis,” IEEE Transactions on Power Delivery, vol. 19, no. 1, pp. 168–173, Jan. 2004.





Annex B

(informative)

Transient recovery voltage (TRV)

B.1 TRV basics

The TRV related to the rated short-circuit interrupting current in accordance with 5.6 is the reference voltage that constitutes the limit of the prospective TRV of circuits, which the circuit breaker is capable of withstanding under fault conditions. Each TRV rating is defined for a three-phase circuit breaker.

At its rated maximum voltage for rated voltages below 100 kV, each circuit breaker must be capable of interrupting three-phase ungrounded terminal faults at rated short-circuit current in any circuit in which the TRV does not exceed the rated TRV envelope.

At its rated maximum voltage for rated voltages 100 kV and above, the user can specify whether the circuit breaker must be capable of interrupting three-phase grounded or three-phase ungrounded terminal faults at rated short-circuit current in any circuit in which the TRV does not exceed the rated TRV envelope. The first phase to clear in an ungrounded fault produces the highest TRV. A graphical explanation is provided in Annex C of IEEE Std C37.011 [B26] and B.4.

By agreement between the manufacturer and the user, the circuit breaker may be rated for three-phase line fault duty. Both the rated system voltage and the grounding of the circuit are major factors affecting the TRV of the circuit. Grounding network implies a longer arc extinguishing window and therefore a breaker tested in an ungrounded network is not automatically suitable for use in a grounded network

In the range of rated voltages from 100 kV to 170 kV, the grounding is sometimes accomplished through a high impedance, which makes these systems effectively ungrounded. In addition, three- phase ungrounded faults are still common, although less so than at voltages less than 100 kV. Therefore, the user can specify the circuit breakers for use in these impedance grounded systems be required to interrupt three-phase ungrounded terminal fault as well.

For rated voltages of 100 kV and above, most systems have the neutral grounded, except in the range of rated voltages from 100 kV to 170 kV as noted above. The three-phase grounded fault is the basis of rating for circuit breakers rated 100 kV and above and applied in effectively grounded systems. This standard also provides the user the option to specify three-phase ungrounded fault as the basis of rating.

The choice between the three-phase grounded and three-phase ungrounded condition is accomplished by choosing the value of the first-pole-to-clear factor kpp in calculating the TRV peak. For ungrounded systems, which are often found at lower rated voltages, the value of kpp is 1.5. For effectively grounded systems, which are the norm at higher rated voltages, the value of kpp is 1.3. The tables of preferred ratings in this standard include the option of both the first-pole-to-clear factors at 100 kV and above.

Two types of TRV waveforms at rated short-circuit current are used based on the voltage class of the equipment.

A four-parameter TRV is used for system voltages of 100 kV and above.

A two-parameter TRV is used for system voltages up to 100 kV.





The two-parameter TRV is also used at all rated voltages for the TRVs for fault currents that are 30% or less of the rated short-circuit current as discussed in 5.7.2.3.1. The two- and four-parameter TRV waveforms are qualitatively described below and are described with equations in B.2. Methods of drawing TRV envelopes by constructing the tangent lines are given in B.3 and B.4. The numerical values of the parameters for preferred ratings are listed in rating tables of this standard.

NOTE—TRV terminology and symbols in this standard are harmonized between IEC and IEEE. The relationship between the new terms used in the standard and older terms used are shown in Figure B.3 and Figure B.4.

B.1.1 Four-parameter TRV for system voltages of 100 kV and above

A four-parameter TRV envelope consisting of three line segments as described below represents this waveform.

The four parameters are described as follows.

u1 = first reference voltage, in kilovolts

t1 = time to reach u1, in microseconds

uc = second reference voltage (the TRV peak value), in kilovolts

t2 = time to reach uc, in microseconds

These four parameters, plus the origin, form two sloped line segments and a third horizontal line segment. These reference lines form an upper boundary to the rated TRV.

The first line segment extends from the volt-time origin up to the point u1, t1.

The second line segment begins at point u1, t1 and extends to point uc, t2.

The third line segment is a horizontal line at the peak voltage uc.

Figure B.1—Four-parameter TRV envelope





As stated, the actual TRV waveform bounded by this four-parameter set of straight lines reaches its peak at a point in time that is later than the point t2 where the straight lines intersect Figure B.6 shows the reference line segments that form the four-parameter TRV envelope.

NOTE—Figure B.7 shows a comparison of four-parameter TRV reference lines to the former IEEE exponential- cosine TRV envelope.

B.1.2 Two-parameter TRV for system voltages up to 100 kV

For voltages up to 100 kV, the TRV approximates to a damped single-frequency oscillation. A two-parameter TRV envelope as shown in Figure B.2 adequately represents this waveform.

The two parameters are described as follows:

uc = reference voltage (TRV peak value), in kilovolts

t3 = time to reach uc in microseconds

These two parameters, plus the origin, form one sloped line segment and a second horizontal line segment. These reference lines form an upper boundary to the rated TRV:

The first line segment extends from the volt-time origin up to the point uc, t3.

The second line segment is a horizontal line at the peak voltage, uc.

Earlier versions of this standard used a 1-cosine wave as the standard TRV envelope with the 1-cosine reaching a peak of E2 at time T2. In this simple case, t3, the time to reach uc, in µs is equal to 0.88 times T2. Figure B.2 shows the reference line segments that form the two parameter TRV envelope.

Figure B.2—Two-parameter TRV envelope

B.1.3 Initial lower boundary to the TRV

The influence of local capacitance on the source side of the circuit breaker slows the rate of rise of the voltage during the first few microseconds of the TRV. This is taken into account by introducing a time delay td in the initial build-up of the TRV wave. The delay line shown in Figure B.1 and Figure B.2 accounts for this initial delay in the TRV and establishes a lower boundary for the initial delayed build-up





of the TRV wave. A delay line is then an additional part of the TRV requirement, which defines an initial lower boundary to the TRV.

The delay line is defined by a voltage parameter u′, a time parameter t′, and a time delay td as listed below and is illustrated in both Figure B.1 and Figure B.2:

u′ = reference voltage, in kilovolts

t′ = time to reach u′, in microseconds

td = time delay, in microseconds

The delay line starts on the time axis at the rated time delay and runs parallel to the first section of the reference line of rated TRV and terminates at the voltage u′ at time coordinate t′.

The values of the time delay are based on the typical system TRVs. For transmission systems at 100 kV and above, the reference time delay is 2 µs at the rated short-circuit current. In an actual test, the TRV must be either tangent to or above the delay line to be a valid test stress on the circuit breaker according to its rating.

For a 1-cosine TRV wave described by the two-parameter reference lines and the parameters uc and t3, a time delay of 0.15 × t3 makes the delay line tangent to the 1-cosine wave from below. This is illustrated in Figure B.4.

B.1.4 Initial transient recovery voltage (ITRV)

The beginning of the TRV may be of importance for some types of circuit breakers. This part of the TRV, called ITRV, is caused by the initial oscillation of small amplitude due to reflections from the first major discontinuity along the conductor. The ITRV is mainly determined by the busbar and line bay configuration of the substation. If the circuit breaker has a short-line fault rating, then the ITRV requirement is considered covered if the short-line fault tests are carried out using a line with insignificant time delay. For details, see the circuit breaker short-line fault test procedure in IEEE Std C37.09.

The ITRV is proportional to the conductor surge impedance and to the current:

ITRV is only applicable to circuit breakers rated 100 kV and above because the bus lengths at lower voltages are too short to produce noticeable ITRVs.

Bus surge impedance is considered to be 260 Ω in contrast to the higher value of 450 Ω used for lines. Therefore, at currents below 31.5 kA, ITRV is not considered significant in comparison to the short-line fault (SLF) TRV.

For circuit breakers installed in gas-insulated substations, the initial TRV can be neglected because of low bus surge impedance and small distances to the first major discontinuity.

ITRV is described further in 5.7.2.3.4.

B.2 Rated TRV parameters

B.2.1 Three factors that influence the TRV parameters

The TRV rating for a three-phase circuit breaker is defined by an envelope of required withstand capability. The parameters, which define the envelope, are based on the characteristic features of the actual system TRVs. TRV parameters are influenced by three factors as follows:





Ur = the rated voltage

kpp = the first-pole-to-clear factor

kaf = the amplitude factor

B.2.2 Circuit breakers rated 100 kV and above in effectively grounded systems

B.2.2.1 Four parameter reference lines

For circuit breakers rated 100 kV and above, a four-parameter reference line envelope as shown in Figure B.1 represents the rated TRV. Equations for the TRV parameters in terms of the three basic factors Ur, kpp, and kaf follow below.

The magnitude of the first reference voltage parameter u1 is as follows:

1/21 0.75 2 / 3pp ru k U (B.1)

The time t1 at which u1 is reached is derived from u1 and the rate-of-rise of recovery voltage (RRRV). RRRV = u1 / t1 as illustrated in Figure B.1.

The rate of rise of the TRV, RRRV = u1 / t1, at the rated short-circuit current for circuit breakers rated 100 kV and above has been established as 2 kV/µs as shown in this standard.

The magnitude of the TRV peak uc at the rated voltage of Ur is described by Equation (B.2):

1/22 / 3c af pp ru k k U (B.2)

where

The amplitude factor kaf is equal to

kaf = 1.4 for terminal faults and short-line faults

kaf = 1.25 for out-of-phase

The first-pole-to-clear factor kpp is equal to:

kpp = 1.3 or 1.5 for terminal faults conditions

kpp = 1.0 for short-line faults conditions

kpp = 2.0 for out-of-phase conditions in grounded systems

kpp = 2.5 for out-of-phase conditions in ungrounded systems.

The rated times t2 to reach the peak voltage parameter uc for terminal and short-line fault switching conditions are related to t1 as follows:

2 1 2 4 100t t t T (B.3)

For out-of-phase (OP) switching conditions:

2 2 2 100t OP t T (B.4)





The rated time to the peak uc of the four-parameter envelope varies with circuit breaker rated voltage as given in this standard.

B.2.2.2 Delay line

The delay line parameters for rated voltage from 100 kV and above are defined as follows. The rated time delay td is listed below:

td = 2 µs for test duty T100 and T60

td = 2 µs for test duty OP1 and OP2

td = 2 µs for the supply-side circuit for short-line fault

td = 0.15 t3 for test duty T30 and T10

Voltage u′ is as follows:

u′ = u1 / 2 for test duties T100 and T60 and the supply side for short-line fault and out-of-phase interrupting

u′ = uc / 3 for test duties T30 and T10

Time t′ is derived from the values of three other parameters, as follows:

td = the time delay

u′ = the peak of the delay line

RRRV = u1 / t1 for four-parameter TRV envelopes

RRRV = uc / t3 for two-parameter TRV envelopes

The time to the delay line peak t′ to the delay line peak u′ is shown in Figure B.1 and Figure B.2 and Equation (B.5):

’ ’ / dt t u RRRV (B.5)

B.2.2.3 Circuit breakers rated below 100 kV

B.2.2.3.1 Two-parameter reference lines

For circuit breakers rated below 100 kV, a two-parameter reference line envelope as shown in Figure B.2 represents the rated TRV. Equations for the TRV parameters in terms of the three basic factors Ur, kpp, and kaf follow below.

The voltage parameter uc, for interrupting rated short-circuit current, is equal to

2 / 3 1/ 2c af pp ru k k U (B.6)

where

kaf = amplitude factor

For overhead line-connected systems:

kaf = amplitude factor = 1.54 for terminal fault and short-line fault





For cable-connected systems:

kaf = amplitude factor = 1.4 for terminal fault and short-line fault

For both overhead line and cable connected systems:

kaf = amplitude factor = 1.25 for out-of-phase

The time parameter t3 is specified based on system parameters. The RRRV is then determined from uc and t3 using the relationship in Equation (B.7):

c 3RRRV /u t (B.7)

At medium voltages under 100 kV, the rated time parameter t3 to the TRV peak uc of the two-parameter envelope varies with circuit breaker rated voltage as given in this standard. For line systems (class S2), time t3 for terminal fault and short-line fault is equal to 4.65 × (uc)0.7 with t3 in microseconds and uc in kilovolts. The equation is derived from the values given in Table 3 of this standard for rated voltages 15.5 kV, 25.8 kV, 48.3 kV, and 72.5 kV. The same equation is used for other rated voltages.

The amplitude factor is affected by the amount of damping in the system to TRV transients:

a) The amplitude factor of 1.54 is the value for overhead line connected systems (class S2).

b) The amplitude factor of 1.4 is the value for cable-connected (class S1).

The preferred TRV values listed in Table 13 and Table 14 for line systems are the ANSI/IEEE values specified for class S2 circuit breakers in this standard.

The preferred TRV values listed in Table 9 and Table 10 for cable systems are harmonized with the IEC values of IEC 62271-100.

Two types of circuit breaker TRV applications are added to describe the two classes of systems for circuit breakers rated less than 100 kV. These two classes of systems, cable systems (class S1) and line systems (class S2), are described in Clause 3 and are also included in IEC 62271-100.

B.2.2.3.2 Delay line

The delay line parameters td and u′ and t′ are defined for rated voltages below 100 kV in this subclause.

Time delay td for terminal faults (test duty T100) is a function of the system, cable, or line, and the switching condition, terminal fault, short-line fault, or out-of-phase switching:

td = 0.15 t3 for terminal fault and out of phase in the case of cable systems

td = 0.05 t3 for terminal fault and short-line fault in the case of line systems

The time delay td for test duties T60, T30, and T10 as well as for out-of-phase interrupting is as follows:

td = 0.15 t3

The voltage parameter u′ is as follows:

u′ = uc / 3 (10)





The time parameter t′ is derived from u′, RRRV = uc / t3, and td according to Figure B.2 and Equation (B.8):

’ ’ / RRRVdt t u (B.8)

B.2.3 Effect of the first-pole-to-clear factor

B.2.3.1 Effect of the first-pole-to-clear factor—Systems less than 100 kV

Because systems below 100 kV are often operated ungrounded (non-solidly earthed), and because three- phase faults are more common in these systems than in higher voltage systems, a first-pole-to-clear factor of 1.5 is required. Therefore, the following relationships are found:

kpp = 1.5 for ungrounded fault conditions (non-solidly earthed systems)

kpp = 1.0 for short-line fault conditions

kpp = 2.0 or 2.5 for out-of-phase conditions

For overhead line-connected circuits:

1/2 1.54 1.5 2 / 3 1.88 c r ru U U (B.9)

For cable-connected circuits:

1/2 1.4 1.5 2 / 3 1.715c r ru U U (B.10)

which are the rated values of uc as given in this standard.

For out-of-phase switching conditions, the amplitude factor kaf is 1.25; however, the first-pole-to-clear factor is higher than for short-circuit conditions:

kpp = 2.5 for ungrounded systems

Therefore, we have the following equation for uc:

1/2 1.25 2.5 2 / 3 2.55 c r ru U U (B.11)

B.2.3.2 Effect of the first-pole-to-clear factor—Systems 100 kV and above

Because most systems operating at 100 kV and above are grounded or effectively grounded, and because three-phase ungrounded faults are very rare (Catenacci et al. [B2]), accounting for less than 1.3% of all faults, a first-pole-to-clear factor of 1.3 is appropriate. Therefore, the following relationships are found:

kpp = 1.3 for effectively grounded systems

1/21 0.75 1.3 2 / 3 0.796r ru U U (B.12)

1/2 1.4 1.3 2 / 3 1.49c r ru U U (B.13)





Table 17 shows TRV values for circuit breakers rated 100 kV and above for use on effectively grounded systems.

Table 18 and Table 20 show TRV values for rated voltages 100 kV and above using a first-pole-to-clear factor of 1.5.

Some systems with rated voltages of 100 kV through 170 kV in some parts of the world are operated as ungrounded or impedance grounded systems where the system neutral is either not connected to ground, that is, the system is ungrounded, or is connected to ground through a high impedance, meaning the system is impedance grounded. In such systems, even a three-phase fault to ground is ungrounded and requires a first-pole-to-clear factor of 1.5.

Some effectively grounded systems may experience more three-phase ungrounded faults than is typical. In this case, the user may wish to require demonstrated performance under three-phase ungrounded faults with a first-pole-to-clear factor of 1.5. The first-pole-to-clear factor in such cases is 1.5, and u1 and uc are then described as follows: kpp = 1.5 for ungrounded or impedance grounded systems

1/21 0.75 1.5 2 / 3 0.919r ru U U (B.14)

1/2 1.4 1.5 2 / 3 1.72 c r ru U U (B.15)

For out-of-phase (OP) switching conditions, the amplitude factor kaf is 1.25; however, the first-pole-to-clear factor is higher than for short-circuit conditions as shown below. The overall effect of kaf × kpp for the OP condition is to produce higher values of u1 and uc as follows:

kpp = 2 for grounded systems

kpp = 2.5 for ungrounded or impedance grounded systems

Therefore, we have the following equations for u1 and uc.

For out-of-phase switching in grounded systems rated at 100 kV and above:

1/21 0.75 2 2 / 3 1.23 r ru U U (B.16)

1/2 1.25 2 2 / 3 2.04 c r ru U U (B.17)

For out-of-phase switching in ungrounded or impedance-grounded systems rated at 100 kV through 170 kV or systems where three-phase ungrounded faults are considered:

1/21 0.75 2.5 2 / 3 1.53 r ru U U (B.18)

1/2 1.25 2.5 2 / 3 2.55c r ru U U (B.19)

B.3 TRV Symbols used in the tables with the two-parameter method

The preferred ratings are for 50 Hz and 60 Hz systems. The two-parameter method is one of the methods used in these tables to represent the TRV. The basic inherent shape of the rated TRV envelope is the “one-minus-cosine” (1–cosine) shape. For the development of the two-parameter method based on the 1–cosine





shape, refer to B.2.2.3.1. The rated interrupting times and peak recovery voltage values and times given are all based on 60 Hz systems.

B.3.1 General explanation of symbols

The symbols used in this standard are as follows and are essentially those in the IEC 62271-series standards.

Ur = rated maximum voltage. Sometimes Ur is represented by V in other standards. It is measured in kV rms.

kpp = first pole to clear factor. It may be represented in other documents as Kf. When systems below 100 kV are operated on non-effectively grounded systems, a first pole-to-clear factor of 1.5 is required.

kaf = transient amplitude factor. It may be represented in other documents as Ka. In systems below 100 kV the amplitude factor can be of 1.4 or 1.54. For out-of-phase interrupting capability the amplitude factor is 1.25 per B.2.2.3.1.

uc = Reference voltage, a peak (crest) value in kV. It is a measure of the TRV. It was referenced as E2 in former documents. It is related to the rated maximum voltage in kV by the formula:

uc = kpp × kaf × 3/2 × Ur

(i.e., for example 1.5 × 1.54 × 3/2 × Ur = 1.886 × Ur for overhead line connected circuits below 100 kV).

t3 = time to reach uc in microseconds, and it is calculated from the old value of T2 by t3 = [T2 * Kt3] / 1.138.

Kt1, Kt2, or Kt3 = Multipliers are defined in Table 2 in the applications guide IEEE Std C37.011, 4.2.1 [B26] and vary according to the voltage and the interrupting current as a percentage of rated short circuit current.

td = is the delay time in microseconds. td for test duty T100 is 0.15 × t3 for Class S1 cable connected systems, and 0.05 × t3 for Class S2 line connected systems at below 100 kV. td is 0.15 × t3 for all test duties T60, T30, and T10, and for out-of-phase interrupting in all cases.

u′ = reference voltage in kilovolts

t′ = time to reach u′ in microseconds = td + (u′ / RRRV)

Comments

If the source of power to a circuit breaker is a single transformer or a bank of transformers and there are no substantial capacitances or loaded feeders connected to the source side of the circuit breaker, the TRV may be more severe than those covered in the ratings of this standard. For such applications, refer to IEEE Std C37.06.1 [B20] for preferred ratings of definite purpose circuit breakers for fast TRV rise time.





B.3.1.1 Figures explaining the symbols

Figure B.3—Graphic showing the two parameters recovery voltage (t3, Uc) used for

voltages below 100 kV and a delay line with the delay time td

a The new symbols used are: uc, u′, td, t′, t3, compared to the old symbols such as E2 and T2. The rated TRV envelope is the “one-minus-cosine” (1–cosine) shape.

Figure B.4—Correspondence between the new two-parameter method representing the recovery voltage for voltages below 100 kV and the old method listed in

IEEE Std C37.04-1999a

B.4 Symbols used in tables with four-parameter method

The preferred ratings are for 50 Hz and 60 Hz systems. Applications at other system frequencies should receive special consideration, see IEEE Std C37.010. The rated interrupting times and peak recovery voltage values and times given are all based on 60 Hz systems.





Values have generally been rounded off. The number of significant digits after the decimal point varies according to the meaning of the value.

The four-parameter method is used in these tables to represent the TRV for circuit breakers rated 100 kV and above and for T100, T60 faults. The four-parameter method is applied for terminal faults (T100, T60), short-line faults, and out-of-phase faults. The two-parameter method is used to represent the TRVs at T30 and T10. The rated TRV envelope has been historically the “higher of an exponential waveform and a 1–cosine waveform” shape.

B.4.1 General explanation of symbols

The symbols used are as follows and are essentially those used in the IEC 62271-series standards.

Ur = rated maximum voltage. Sometimes Ur is represented by V in other standards.

kpp = first pole to clear factor. It may be represented in other documents as Kf. Systems below 100 kV may be operated on non-effectively grounded systems and a first pole-to-clear factor of 1.5 is required for terminal faults. For 100 kV and above, systems are usually grounded, and the factor is 1.3 for terminal faults in this case. In certain applications where the systems may be grounded and where the likelihood of non-effectively grounded faults cannot be ignored, the factor of 1.5 for terminal faults is used.

kaf = transient amplitude factor. It may be represented in other documents as Ka. In systems 100 kV and above the amplitude factor can be of 1.40, at T100 and 1.25 for out-of-phase interrupting capability.

u1 = first reference voltage in kV, a peak (crest). It is calculated as:

u1 = 0.75 × kpp × 3/2 × Ur

t1 = time to reach u1 in microseconds. It is derived from u1 and the specified value of the RRRV, u1 / t1.

uc = second reference voltage a peak (crest) value in kV. It is a measure of the TRV. It was referenced as E2 in former documents. It is related to the rated maximum voltage in kV by the formula:

uc = kaf × kpp × 3/2 × Ur, where kaf is equal to 1.4 for terminal fault T100 and short-line faults and 1.25 for out-of-phase faults.

t2 = time to reach uc in microseconds (used only in the four parameters method) is equal to 4 t1 for test duty T100 and for the supply side circuit for short-line fault, between 2 t1 and 4 t1 for out-of-phase interrupting. Time t2 is equal to 3 t1 for T60.

t3 = time to reach uc in microseconds (used only in the two parameters method) and it is calculated from the old value of T2 by t3 = [T2 * Kt3] / 1.138.

Kt1, Kt2, or Kt3 = Multipliers are defined and shown in Table 1 of the applications guide IEEE Std C37.011, 4.2.1 [B26] and vary according to the voltage and the interrupting current as a percentage of rated short circuit current.

td = is the delay line in microseconds and is between 2 μs and 0.28 t1 for test duty T100, between 2 μs and 0.3 t1 for test duty T60, between 2 μs and 0.1 t1 for the out-of-phase test duty.

u′ = reference voltage in kV and is equal to u1 / 2 for test duties T100 and T60 and for the supply side circuit for the short-line fault.

t′ = time to reach u′ in microseconds.





B.4.1.1 Figures explaining the symbols

Figure B.5—Four-parameters recovery voltage (t1, u1, t2, uc) used for voltages 100 kV and

above and a delay line with the delay time td and the two defining parameters u′ and t′

Figure B.6—Representation by four parameters of a prospective TRV





Figure B.7—Comparison of four-parameter TRV reference lines to the

exponential-cosine TRV-envelope defined in IEEE Std C37.04-1999





Annex C (normative) Exposure to pollution

C.1 General

The quality of ambient air with respect to pollution by dust, smoke, corrosive and/or flammable gases, vapors, or salt is a consideration under normal and special service conditions (refer to Clause 4 of this standard). This annex defines levels of pollution as well as recommendations for the minimum specific creepage distance across external insulation.

C.2 Pollution levels

For purposes of standardization, the levels of pollution, very light, light, medium, heavy, and very heavy are qualitatively defined. The qualitative examples given in Table C.1 are approximate descriptions of some typical corresponding environments. Other more extreme environmental conditions may merit further consideration, e.g., snow and ice in heavy pollution, heavy rain, and arid areas. For these special conditions, reference is given to IEC 60815 parts 1, 2, and 3.

C.3 Minimum requirements for switchgear

The minimum creepage distance expressed as a specific creepage in millimeters per kilovolt are for the normal service conditions of atmospheric contamination and altitudes up to 1000 m. This minimum creepage provides generally satisfactory service operation under these conditions.

For each level of pollution described in Table C.1, the corresponding minimum recommended nominal unified specific creepage distance (USCD) in millimeters per kilovolt across the insulator is given in Table C.2.

NOTE—The information in Table C.1 is adapted from IEC 60815-1; the values in Table C.2 are taken from IEC 60815-2.





Table C.1—Environmental examples by site pollution severity (SPS) class

SPS Class Example of typical environments Very light Examples of very light environmental conditions:

> 50 km from any sea, desert, or open dry land a > 10 km from man-made pollution sources b Within a shorter distance than mentioned above of pollution sources, but: • prevailing wind not directly from these pollution sources • and/or with regular monthly rain washing

Light Examples of light environmental conditions: 10–50 km from the sea, a desert, or open dry land a 5–10 km from man-made pollution sources b Within a shorter distance than example 1 from pollution sources, but: • prevailing wind not directly from these pollution sources • and/or with regular monthly rain washing

Medium Examples of medium environmental conditions: 1) 3–10 km from the sea, a desert, or open dry land c 1–5 km from man-made pollution sources b Within a shorter distance than mentioned above of pollution sources, but: • prevailing wind not directly from these pollution sources • and/or with regular monthly rain washing

2) Further away from pollution sources than mentioned in example 3, but: • dense fog (or drizzle) often occurs after a long (several weeks or months) dry pollution

accumulation season • and/or heavy, high conductivity rain occurs • and/or there is a high non-soluble deposit level (refer to IEC 60815-1)

Heavy Example Within 3 km of the sea, a desert, or open dry land c Within 1 km of man-made pollution sources b With a greater distance from pollution sources than mentioned but: • dense fog (or drizzle) often occurs after a long (several weeks or months) dry pollution

accumulation season • and/or there is a high non-soluble deposit level (refer to IEC 60815-1)

Very Heavy Example Within the same distance of pollution sources as specified for “heavy” areas and: • directly subjected to sea-spray or dense saline fog • or directly subjected to contaminants with high conductivity, or cement type dust with high

density, and with frequent wetting by fog or drizzle • desert areas with fast accumulation of sand and salt, and regular condensation

a During a storm, the equivalent salt deposit density (ESDD) level at such a distance from the sea may reach a much higher level. b The presence of a major city will have an influence over a longer distance, i.e., the distance specified for sea, desert and dry land. c Depending on the topography of the coastal area and the wind intensity.





Table C.2—Minimum nominal specific creepage distance by site pollution severity (SPS) class

SPS Class Minimum recommended nominal unified

specific creepage distance (USCD) a (mm/kV)

Very light 22 Light 27.8 Medium 34.5 Heavy 43.3 Very Heavy 53.7 NOTE—The specific creepage distance values given in this table apply to glass and ceramic insulators. Values for other materials are under consideration. IEC 60815-3 recommends that the creepage distance of the polymeric insulators should be the same as that for the ceramic insulators. a The unified specific creepage distance (USCD) is the creepage distance of an insulator divided by the rms value of the highest operating voltage across the insulator [IEC 60815-2].





Annex D

(informative)

AC arc furnace switching

D.1 Repetitive duty circuit breakers for AC arc furnace switching

Power operated circuit breakers particularly designed for arc furnace switching, when operating under usual service conditions, shall be capable of operating at least the required number of times given in Table D.1. The operating conditions and the permissible effect upon the circuit breakers are given in the following paragraphs. For each column, all paragraphs listed shall be considered.

D.2 Servicing

Servicing shall consist of adjusting, cleaning, lubricating, and tightening, as recommended by the manufacturer. The operations listed are on the basis of servicing at intervals of 6 months or less.

D.3 Circuit conditions

Each operation referred to in Table D.1 consists of closing and opening of the circuit breaker under the specified load conditions.

D.4 Operating conditions

The frequency of operation shall not exceed twenty in 10 min or thirty in 1 hr. Rectifiers, air systems, or other auxiliary devices may further limit the frequency of operations.

Servicing shall be applied at intervals no greater than those shown in the third column of Table D.1.

D.5 Conditions of the circuit breaker

After the operations shown in Table D.1, the following shall have taken place:

a) No parts shall have been replaced.

b) The circuit breaker shall meet all of its current, voltage, and short circuit current ratings.

D.6 Minimum operations under fault conditions

If a fault operation above 9,000 amperes occurs before the completion of the permissible operations, maintenance shall be performed according to the manufacturer’s instructions.





D.7 Schedules

Table D.1—Operating capabilities – circuit breakers for arc furnace transformer switching

Circuit breaker rating Maximum number of operations Number of operations

Rated maximum voltage, kV

Rated continuous current, amperes Between servicing No-load

mechanical Switching and

interrupting

4.76 through 123 1200, 2000, 3000 1,000 20,000 See schedule 1 through 5

Schedule 1: 10 000 operations interrupting no-load or load currents of less than 100 A, plus 5000 operations interrupting fault currents up to 350 A, plus one opening operation (O) at rated short circuit current.

Schedule 2: 2500 operations interrupting no-load or load currents no less than 1200 A, plus 200 operations interrupting fault currents up to 3600 A, plus one opening operation (O) at rated short circuit current.

Schedule 3: 2000 operations interrupting no-load or load currents less than 2000 A, plus 200 operations interrupting fault currents up to 6000 A, plus one opening operation (O) at rated short circuit current.

Schedule 4: 1000 operations interrupting no-load or load currents less than 3000 A, plus 50 operations interrupting fault currents up to 9000 A, plus one opening operation (O) at rated short circuit current.

Schedule 5: 12 000 operations interrupting no-load or load currents less than circuit breaker continuous current rating, plus 3000 operations interrupting fault currents up to 4000 A, plus one opening operation (O) at rated short circuit current.





Annex E

(informative)

Free standing current transformers

E.1 Rated primary and secondary current

The maximum rated primary current of a wound type current transformer should be at least equal to the rated continuous current and the load current carrying capability of the circuit breaker with which the current transformer is to be used. Current ratings for multi-ratio current transformers for relaying service should be as shown in Table 31 The current ratings for single ratio current transformers for metering service should be 300:5, 600:5, 800:5, 1200:5, 1500:5, 2000:5, and 3000:5.

E.2 Polarity lead markings

Polarity and lead markings for multi-ratio and single ratio secondaries for current transformers should be as shown in Figure 12, Figure 13, and Figure 14. Single ratio secondaries with two leads should be marked with suitable prefix letters and suffix numbers.

E.3 Secondary leads and terminations

Secondary leads should be brought out to accessible terminal boards with polarity, phase, and lead designations shown on suitable connection diagrams. Terminal boards should be equipped with means for short circuiting individual secondaries. Where applicable, secondary leads should be brought out through suitable oil and gas tight seals.

E.4 Primary terminal connection mechanical loading

The maximum mechanical loading which may be applied to the primary terminal connection of a current transformer should not exceed that required for a circuit breaker terminal connection (see 7.18.4).

E.5 Typical connection of secondary burdens

Typical connection for secondary burdens should be as shown in Figure 15, Figure 16, Figure 17, and Figure 18, except that all secondaries should be on the same side of the circuit breaker.

E.6 Test procedures

The following design and production tests should be made on instrument current transformers for use on or with circuit breakers.

E.6.1 Design tests

The design test requirements and procedures should be as specified in IEEE Std C57.13 and in accordance with the following additional requirements:





a) When rated dielectric strength is not demonstrated in accordance with IEEE Std C57.13, the test requirements and procedures as specified in IEEE Std C37.09 should be used.

b) Wet dielectric tests should be made with values in accordance with IEEE Std C37.09. When the current transformer is part of the circuit breaker structure, the wet tests on the circuit breaker should include the current transformer. When the current transformer is not part of the circuit breaker or when it can be set apart from the circuit breaker, the current transformer should be tested separately.

c) Dielectric tests should be made in accordance with IEEE Std C37.09. Where current transformers are closely associated with the circuit breaker, that is mounted on the circuit breaker supporting structure or on separate pedestals at the end of the pole units, the dielectric tests should be made on the combined circuit breaker and current transformer, unless it can be established otherwise that there is no reduction of insulation withstand strength because of the adjacent apparatus.

d) Switching surge withstand voltage tests (if applicable) should be made in accordance with IEEE Std C37.09.

E.7 Production tests

a) Accuracy tests on free standing current transformers should be made in accordance with IEEE Std C57.13. All other tests should be made in accordance with IEEE Std C37.09.

b) Free standing current transformers should be tested to meet the power frequency withstand voltage test values required this standard.





Annex F

(normative)

Extended electrical endurance (class E2)

F.1 General

IEC 62271-100 includes provisions for circuit breakers with extended electrical endurance, termed ‘circuit breaker class E2’: circuit breaker designed so as not to require maintenance of the interrupting parts of the main circuit during its expected operating life, and only minimal maintenance of its other parts. This annex is intended to provide for harmonized requirements where extended electrical endurance is required, for example class S2 circuit breakers intended for auto-reclosing duty which may be exposed to a significant number of low-level faults on connected overhead lines. Table F.1 provides requirements for class E2 circuit breakers intended for auto-reclosing duty (normally class S2, rated 72.5 kV and lower).

Table F.1—Electrical endurance requirements on class E2 circuit breakers

Testing current (percentage of rated

short-circuit breaking current) %

Operating sequences Number of operating sequences (list 1) a

Number of operating sequences

(list 2)

Number of operating sequences

(list 3)

10 O 84 12 —

O - 0.3 s - CO 14 6 — O - 0.3 s - CO - t - CO 6 b 4 b 1 b

30 O 84 12 —

O - 0.3 s - CO 14 6 — O - 0.3 s - CO - t - CO 6 b 4 b 1 b

60 O 2 8 15 O - 0.3 s - CO - t - CO 2 b 8 b 15 b

100% (symmetrical) O - 0.3 s - CO - t - CO 2 b 4 b 2 b a List 1 is preferred. List 2 may be used as an alternative to list 1 for circuit breakers used for effectively earthed neutral systems. Calculations have been carried out on the basis of Electrical endurance and reliability of circuit breakers. Common experience and practice of two utilities. Pons et. al. [B33]. These calculations are applicable for certain circuit breakers types (single-pressure SF6 vacuum circuit breakers). Calculation results may be different for other types of circuit breakers. Using these calculations and setting the wear generated by list 1 at 100%, list 2 results in 125%, and list 3 in 134%. Therefore, list 3 may be used as an alternative to list 1 and to list 2 to reduce the number of different test circuits. b When no reconditioning is made on the sample after the basic short-circuit test sequences, the test already carried out may be taken into account in determining the number of additional operating sequences required to satisfy the requirements of the basic endurance testing. In practice, this means reducing these figures marked b by 1.


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