tec-spec-chap-A

8/2/2019 tec-spec-chap-A

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CHAPTER - A

TECHNICAL SPECIFICATION FOR 24kV SWITCHGEAR

2.1 SCOPE OF WORK

2.1.1 This part of specification covers the design, manufacture, assembly, testingat manufacturer's works before dispatch, packing, forwarding, erection,testing and commissioning of 24 kV indoor switchgear panel boards withSF6/Vacuum circuit breaker (draw out type) relays, measuring and indicatinginstruments as specified hereunder and in the schedule of requirements forsite located at an altitude of 1061 m above from mean sea level at Jhakri .

2.1.2 The switchgear should be complete in all respect with metallic connectors,interrupting chambers, operating mechanism, control cabinet, interlocks,protective relays, auxiliary switches, indicating devices, supporting system,metering cubicle with sufficient space for current, voltage transformers, etc.

2.1.3 The scope of the supply also includes necessary special tools and plantsrequired for erection and maintenance. The bidder shall also list out thedetails of tools & plants being covered under the scope of supply. Thebidder shall recommend necessary spares required for normal operation andmaintenance of the switchgear for a period of five years.

The bidder shall co-ordinate with his sub-vendors, if any, of sub-stationtransformer & station transformer on all matters of common concern in orderto ensure correct installation and operation of the switchgear system.

In addition to above, the bidder shall offer the following services:-

a) Over land transportation covering freight and insurances fordelivery at site.

b) Storage and preservation at site till installation andcommissioning.

c) Complete erection, testing and commissioning at site.

d) All other works incidental and connected with above servicesfrom delivery up to the handing over the equipments and thesystem after commissioning.

2.2 STANDARDS

2.2.1 The switchgear panels with its accessories shall conform in all respects tothe requirements of latest edition of IS/IEC specifications except formodifications specified herein. The equipment manufactured according toany other National/International standards, which ensure an equal or betterquality than the provision of IS/IEC specifications, shall also be acceptable.

The salient point of difference between the proposed standards andprovision of the specifications shall be clearly brought out in the tender. Acopy of English Version of such standards shall be enclosed with the tender.


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2.2.2 The list of standards mentioned in this specification and to which theswitchgear panels and its components shall generally conform, is givenbelow:-

1. IEC-56/IS-13118 High Voltage A.C. Circuit Breakers.

2. IEC-376 Specifications and acceptance of newsulphur hexaflouride gas

3. IEC-298 High Voltage metal enclosedswitchgear and control gear.

4. IEC-137 Bushing for alternating Voltage above1000 Volts.

5. IEC-71 Insulation co-ordination.

6. IEC-694 Common clauses for high voltageswitchgear and control gearstandards.

7. IEC-267 Guide for testing of circuit breakerswith respect to out of phase switching.

8. IEC-185 Specification for current Transformers.9. IEC-186-1969 Voltage Transformers

10. IEC Study Group DEC.1981 No.IEC-17A.

Sealing of interrupters.

11. IS-2516 Specification for alternating currentcircuit breakers.

12. IS-2099 High voltages porcelain bushing.

13. IS-3072 Installation and maintenance ofswitchgear.

14. IS-1554 PVC insulated cables upto andincluding 1100 volts.

15. IS-5 Colors for ready mixed paints.

16. IS-2705 (Part-I to IV) Specification for current Transformers.

17. IS-3156 Specification for voltageTransformers.

18. IS-1985 (Part-I) General Requirement.

19. IS-1965 (Part-II) Measurement voltage transformers.

20. IS-1966 (Part-III) Protection voltage transformerelectromagnetic type.

21. IS-4146 Application guide for VT.

22. IS-8714 Electrical protective relays for the use

in seismic area23. IS-3842 (Part-I to

application guide XXII)Electrical relays for AC systems

24. IS-3231 Electrical relays for power systemprotection.

25. IS-9124 Electrical relays, guide forMaintenance and field-testing.

26. IS-5834 (Part-I to III) Electrical timer relays for industrialpurposes.

27. IS-8686 Static protective relays.

28. IS-142 Specification for electrical protectiverelay.

29. IS-722-1977(Part-I toIX)

A.C. Electricity meters.

30. IS-11426 Alternating current precision kilowatt


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hour meter clause 0.5 for testingpurpose.

31. IS-1248 Indicating instruments.

32. IS-375 Bus bars, main connection & Aux.wiring marking & arrangement.

33. IS-6875 Control switches (LV switching

devices for control and auxiliarycircuit)

34. IS-9224 (Part-II) HRC cartridge fuse links.

35. IS-2147/IS-3427 Degree of protection provided byenclosures for switchgear cubicles

36. IS-3202 Climate roofing for Electricalequipment.

37. IS-345 Code for wiring numbers.

38. IS -6005 Code of practice for phosphating Ironand Steel

39. IS-5082 Wrought Aluminum & Aluminum

Alloys for electrical purposes40. IS-12729:1988 Switchgear & control gear for voltages

exceeding 1988 1000V GeneralRequirements

41. IS-2208 Specification for HRC fuses.

2.3 GENERAL REQUIREMENTS OF SWITCHGEAR PANELS

2.3.1 Switchboard Cubicle Type and Details

2.3.1.1 The 24 kV totally metal clad SF6 switchgear shall be housed in a cubiclealong with its control and relay panel in a separate compartment. Theswitchgear shall be horizontally with drawable extensible modularconstruction type, suitable for indoor installation. Each switchgear cubicleshall be complete with SF6 type circuit breakers, bus-bars, instrumenttransformers, instruments, protective relays, control cables and 24 kVcable boxes, glands, all necessary control wiring and auxiliary devicesrequired to perform its function.

2.3.1.2 The cubicle shall be of dust, vermin proof construction and shall be providedwith degree of protection not less than IP-46 as per IS-2147. Each unit shall

have its own flush type instruments panel. All instruments, control switches,indicating devices and relays shall be mounted on the front of panel. Thedesign and arrangement of equipment shall be such that an adequate spaceand access is provided for inspection and maintenance of wiring terminalswitches, cable and cables boxes etc.

2.3.1.3 The general arrangement of placement of the various components of theswitchgear shall be as under:

a) The instrument and protective relays shall be placed in a compartmenton the front of the cubicle.

b) The truck mounted SF6 circuit breaker including interrupter shall beplaced in such a way that the trolley can be withdrawn from thefront side of the cubicle.


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c) The voltage transformer shall be mounted on the bus bars and thebus chamber shall be located on right half top part of the cubicle.

d) C.T. and cable termination chamber shall be located below thebus bar at the rear of the panel so that ready access is available byopening the back cover. It should be spacious enough toaccommodate three numbers epoxy CTs with 95 sq.mm. aluminiumconductor 22kV power cable (XLPE TYPE).

2.3.2 CONTROL RELAY PANEL

2.3.2.1 Composite Panels

Control board and relay panels shall be of composite type consisting ofvertical stationary front panels with equipment mounted thereon andhaving wiring access. Height of each cubicle shall not exceed 2450mm.

2.3.2.2 Constructional Features

2.3.2.2.1 The panels shall not be less than 2mm thick of cold rolled sheet withangle or channel edge bent to 6mm radius, seam welded at corners andground smooth. Panels shall be bolted at the bottom to a suitable steelchannel base which with necessary framing and cross-bracing will holdthe structure rigidly together to form a self-supporting dead front type ofstructure. Suitable grouting anchor bolt holes shall be provided in thechannel base. Anchor bolts and grouting bolts shall also form the part ofsupply. Butt joints on outside surfaces will be permitted. Outside panelsshall not be drilled or welded for attaching wire, resistors, or switchboard

devices where such holes or fastening will be visible from the front of thepanel. All screws and bolts used for assembling switchboard members andpanels also for mounting wire cleats and switchboard devices shall beprovided with lock washers or other locking devices. Vertical edges ofpanels shall be so formed and bolted together that no part of edgeexposed to view will pass a 0.8mm gauge. Flat surfaces on the face ofany panel shall not deviate more than 1.6mm from a true plane. Sides, topsand doors shall be stiffened where necessary to prevent noticeabledeflection and twisting when removing, opening or resisting an externalload of 23 kg(50 pounds) applied perpendicular to any point on thesurface. To prevent wrapping of panels, all heavy devices shall be

supported by means of rear-mounted brackets or straps. The panels, trimdoors and frames shall match and shall present a neat appearance.Electrical clearance shall conform to applicable standards and shall beprovided without cutting away the adjacent steel framework. All side andtop/rear or bottom edges of cable cutout shall be provided with split-pipe sleeves to provide protection. The supporting structure enclosuresshall be capable of withstanding the tropical climatic condition,change of ambient temperature, severe dust storm, very high relativehumidity that are prevailing at the site. It shall be capable to withstandseismic acceleration of 0.5g in horizontal as well as in vertical direction.

2.3.2.2.2 Necessary arrangement shall be provided for bolting together the adjacentpanels.

2.3.2.2.3 The panels shall be completely enclosed to ensure dust, moisture andvermin proof atmosphere. The degree of protection for main enclosure andwithin the cubicle should be as per the IS-2147.


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2.3.2.2.4 The doors, removable covers and panels shall be fitted with gaskets.

2.3.2.2.5 Metal sills in the form of metal channels properly drilled shall befurnished by the tenderer along with anchor bolts and necessary hardwarefor mounting the panels. These shall be dispatched in advance withreference to the dispatch of the respective panels so that these may beinstalled and leveled when concrete foundations are poured. Panels shallhave additional rolled channel plinth at the bottom with smooth bearingsurface. The panels shall be fixed on the embedded foundation channelswith intervening layers of anti-vibration strips made of shock absorbingmaterials which shall also be supplied by the tenderer.

2.3.2.2.6 Power & control cable entries to the panels shall be made either from thebottom, back or from the top of panels, decision to this effect shall betaken at the time of final engineering of the drawings of equipments and itslayout, keeping in view of the space and blockout already left. The

blanking plates of the panels shall be fitted with removable gland platesfor fixing the cable glands, the sizes of which shall suit the external cablesto the panel. Cable glands shall be screened type, made of brass and shallbe suitable for XLPE, PVC and screened cables. Necessary foundationdrawings showing cables entry positions and foundation bolt locationshall be supplied by the bidder.

2.3.3 Painting

All sheet steel shall be phosphated in accordance with IS-6005 "code ofpractice for phosphating iron and steel".

Final colour of the panels shall be pebble grey as per RAL-7032 orequivalent as per colour code IS-5.

Relay and Instruments: EGG Shell/Bright black Circuit Label: White letteron black label.

2.3.4 Mounting

All equipment on and in panels shall be mounted and completely wired tothe terminal blocks ready for external connections. All equipment on front

of the panel shall be mounted flush or semi flush. In case of semi flushmounting only flange or bezel shall be visible from the front.

The equipment shall be mounted such that removal and replacement can beaccomplished individually without interruption of service to adjacent devicesand are readily accessible without the use of special tools. Terminalmarking shall be clearly visible.

Cut outs and wiring for loose supply items shall be according to thecorresponding equipment manufacturers drawings. Cut outs provided forfuture mounting of equipment shall be properly blanked off.

The center line of switches, push buttons and indicating lamps shallmatch to give a neat and uniform appearance. Their center line shall not belocated less than 750mm from the bottom of the panel. Likewise the centerlines of relays, meters and recorders shall not be less than 450mm from the


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bottom of the panel. No equipment shall be mounted on the doors withoutprior approval of the purchaser.

All the equipment connections and cabling shall be designed andarranged to minimize the risk of fire and damage which may be caused byfire.

2.3.5 Mimic Diagram

Coloured mimic diagram with symbols showing the exact representation ofthe system complete with symbols and colour strips to represent thebuses, feeders, transformers and semaphore indicators for breakersshall be provided in the front of the control panels in accordance with theprovision of respective standards.

Mimic diagram shall be screwed on the panels and shall be made ofanodized aluminum or plastic of approved fast colour material which shall

be screwed on the panel and can be easily cleaned. Alternatively mimicdiagram may also be painted on the panels. The width of the mimic busshall not be less than 10mm and shall be painted in live green colour as perIS:220. The semaphore indicators for breaker positions shall be sopositioned in the mimic such that the breaker closed position shallcomplete the continuity of the mimic. Similarly for control switches of stayput type when mounted in the mimic, the close position of the switch shallcomplete the mimic.

2.3.6 Panel Wiring

2.3.6.1 The panels shall be supplied completely wired internally toequipment and terminal blocks and ready for the external cableconnections at the terminal blocks. When panels are arranged to be locatedadjacent to each other all inter-panel wiring and connection betweenthe panels shall be furnished and the wiring shall be carried out internally.

2.3.6.2 All wiring shall be carried out with 1100 Volts grade, single core, strandedcopper conductor wires with PVC insulation and shall be flame proof, verminand rodent proof. The minimum size of the stranded copper conductorused for internal wiring shall be as follows:

a) All circuits except current & 1.5 mm2voltage transformer circuits

b) Current transformer, voltage 4 mm2

transformer circuits & Power wiring

2.3.6.3 Wiring ducts bundles and supports

A suitable wiring duct system shall be installed for all inter panel wiringand shall provide for easy access for inspection and replacement. Allwiring shall be installed in wiring channels and ducts as far as possible.The wire duct system shall have space available for 30% additionalwires to be added in future. Exposed wiring shall be kept to a minimumand where used, shall be formed into compact wire bundles, bound togetherand supported. Binding and support shall not cause damage or cold flow tothe insulation. Groups of exposed wires shall be run straight horizontally orvertically with short radius right angle bends. Each wire shall be protected


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where it leaves a channel or a duct. Wiring supports shall be of heavygauge rust proof material or steel with rust resisting finish equivalent tosherardizing or cadmium-zinc plating. Hinge wire shall be used betweenstationary panels and hinged or swinging panels, and shall be formed inwire loops or bundles at least two feet long which shall provide rotationaround the longitudinal axis of the conductors.

2.3.6.4 Auxiliary bus wiring for AC and DC supplies, voltage transformer circuits,annunciation circuits and other common services shall be providedsuitably in the panels running throughout the entire length of the panels.These buses shall have a nominal cross section copper equivalent of 4mm

2and shall be suitably insulated along their run.

Wire terminations shall be made with solderless crimping type oftinned copper lugs which firmly grip the conductor. Insulated sleeves shallbe provided at all the wire terminations. Engraved core identification plasticferrule marked to correspond with panel wiring diagram shall be fitted

tightly at both ends of each wire and shall not fall off when the wire isdisconnected from the terminal blocks of each wire. The numbers shown inthe wiring diagram shall be in accordance with IS-345. All wires directlyconnected to trip circuit breaker or device shall be distinguished bythe addition of a red coloured or lettered ferrule. Numbers 6 and 9 shallnot be included for ferrules purposes. The colours for auxiliary wiring shallbe as per IS-375.

2.3.6.5 Supplier shall be solely responsible for the completeness andcorrectness of internal wiring and for the proper functioning of the connectedequipment.

2.3.7 Terminal Blocks

2.3.7.1 All internal wiring to be connected to the external equipment shallterminate on terminal blocks, preferably vertically mounted on theside of each panel. Terminal blocks shall be 1100 V grade and have 10amps. continuous rating, one piece moulded complete with insulatedbarriers, stud type terminals, washers, nuts locking nuts and identificationstrips. Terminal block design shall include a white fibre marking strip withclear plastic, slip on/clipon terminal covers. Marking on the terminal stripshall correspond to wire number on the wiring diagrams. Not more than

two wire shall be connected to any terminal.

2.3.7.2 Provision shall be made for training and supporting incoming cablesfrom the point of entrance to the termination on the terminal blocks.

2.3.7.3 Short circuiting terminal blocks shall be furnished for all current transformercircuits and shall have in addition to above features, provision forshorting together all leads from each C.T. without first opening any circuit.Necessary test links isolating facilities and earthing facilities shall also beprovided.

2.3.7.4 At least 30% spare terminals shall be provided on each panel and thesespare terminals shall be uniformly distributed on all terminal blocks.

2.3.7.5 Unless otherwise specified, terminal blocks shall be suitable forconnecting the following conductors or purchaser's cables.


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a) All circuits except CT&PT circuit 1.5 mm

2

b) CT & PT circuits 4 mm2

2.3.7.6 There shall be a minimum clearance of 250 mm between the first row ofterminal blocks and the associated cable gland plate. Also the clearancebetween two rows of terminal blocks shall be a minimum of 150mm.

2.3.7.7 Arrangement of the terminal block assemblies and the wiring channelswithin the enclosure shall be such that a row of terminal blocks is runparallel and in close proximity along each side of the wiring duct to providefor convenient attachment of internal panel wiring. The side of the terminalblock opposite to the wiring duct shall be reserved for the external cableconnection. A steel strip shall be connected between adjacent terminalblock row at 50mm interval for support of incoming cables. Drawingsshowing proposed arrangement of terminal block and supports for incomingcables shall be subject to approval.

2.3.7.8 All necessary cable terminating accessories such as gland plates, packingglands, crimp type tinned copper lugs supporting clamps and bracket wiringtroughs and gutters etc. for cable shall be included in the scope of supply ofthe bidder.

2.3.8 Phase Arrangement

The standard phase and poles arrangement when facing the front of theequipment shall be R-Y-B and plus-minus, from Left to Right, from top tobottom, from front to back. Front and rear panels of the switch board

shall be considered separately for purpose of phase and polearrangement. All relays, instruments other devices, buses and equipmentinvolving 3 phase circuits shall be arranged and connected in accordancewith the standard phase arrangement where possible. Similar device,shall be wired alike.

2.3.9 Earthing

All panels shall be equipped with an earth bus securely fixed along with theinside of rear of panels. The materials and the sizes of the bus bar shallbe at least 25x6mm copper unless specified otherwise. The buses shall

be bolted to the frame of each panel in such a way as to make goodelectrical contact with each panel or section. The bolted contact surfacesbetween copper and aluminum shall be silver plated. When severalpanels are mounted adjoining each other, the earth bus shall be madecontinuous and necessary connectors and clamps for this purposeshall be included in the scope of supply of the bidder. Provisionshall be made for extending the earth bus bars to future adjoining panelson either side.

2.3.10 Name Plates and Markings

2.3.10.1 All equipment mounted on front and rear side as well as equipmentmounted inside the panels shall be provided with individual name plateswith equipment designation engraved. Also on the top of each panel onfront as well as rear side large and bold name plates shall be provided for


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circuit/feeder designation. These circuit labels shall be larger than the othername plates.

2.3.10.2 All front mounted equipment shall also be provided at the rear withindividual name plates engraved with tag numbers corresponding to theone shown in the panel internal wiring to facilitate easy tracing of thewiring. The name plates shall be mounted directly by the side of therespective equipment wiring and shall not be hidden by the equipmentwiring.

2.3.10.3 Name plates shall be made of non-rusting metal or plastic material.Name plates shall have black back ground and white engraving letteringin English. It should be fastened to the panels with black finished screws.The name plate inscription and size of name plates and letter shall besubmitted to the purchaser for approval.

2.3.10.4 Each instrument and meter shall be prominently marked with the quantity to

be measured (e.g. kV, A, MW, etc.) All relays and other devices shall beclearly marked with manufacturer's name, serial numbers and electricalrating data.

2.3.10.5 Each switch shall have clear inscription identifying its function e.g."BREAKER" "52" "AMMETER" etc. Similar inscription shall also be providedon each device whose function is not otherwise identified. If any switchdevice does not bear this inscription, separate name plate giving itsfunction shall be provided for it. Switch shall also have clear inscription foreach position indication e.g. Trip-Neutral-Close, "ON-OFF", "R-Y-B-OFF"etc.

2.3.11 Switches

Control and instrument switches shall be of rotary operated typepreferably with silver to silver faced contacts of adequate making,carrying and breaking current ratings and shall be provided witheasily removable protective terminal covers and escutcheon plates clearlymarked to show operating position and shall be suitable for flush mountingwith only switch front plates and operating handle projecting out. Theconnections shall be from the back. The contact assembly at the back of theswitch shall be enclosed in dust proof removable covers.

The selection of operating handles for the different types of switches shallbe as follows:

a) Breaker control switches Pistol grip blackb) Selector switches Oval, black

c) Instrument switches Round, blackd) Protection Transfer Pistol grip lockablee) Annunciator, silence and Momentary contact

reset switches type with spring returnto normal position

Circuit breaker control switches shall be of three position, spring returnto neutral type, and shall be provided with target which shall indicate thelast operation of the switch. The control springs, shall be strong androbust enough to prevent inadvertent operation due to light touch.


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Adequate number of spare contacts shall be provided on breaker controlswitch for control interlocking, annunciation and discrepancy indication.Instrument selection switches shall be of maintained contact (Stay-put)type. Ammeter selector switches shall have make before break typecontacts so as to prevent open circuiting of CT secondary when changingthe position of the switch. Voltmeter selector switch for AC shall be suitablefor reading all line to line voltage for effectively earthed system.

Lockable type of switches which can be locked in particular position shallbe provided when specified. The key locks shall be fitted on the operatinghandles. The contact rating of the switches shall be as follows:-

________________________________________________________Description Contact rating in Amps.

240 VAC 220 VDC----------------------------------------------------------------------------------------------a) Make & carry continuously 10 10

b) Make & carry for 0.5 Sec. 30 301. Resitive load (watt) 7 32. Inductive load (watt) with 7 2

L--- = 40 millisec.R

_______________________________________________________

2.3.12 Indicating Lamps

2.3.12.1 Indicating lamps shall be of miniature switch board type suitable for

panel mounting with rear terminal connections. Lamps shall be providedwith series connected resistors preferably built in the lamp assembly toavoid short circuiting of control supply in the event of short circuiting oflamp. The supply for these lamps shall be from 220 V DC station batteryunless stated otherwise. Lamps covers shall be of screwed on type,unbreakable, and moulded from heat resisting material. They shall betranslucent to diffuse light. Unless otherwise stated the lamp covers shallbe coloured as:

a) "Red" for indicating closed position of breakers.

b) "Green" for indicating open position of breakers.

c) "White" for control supply monitoring.

d) "Amber" for miscellaneous indications.

2.3.12.2 Colour caps shall be screwed into the front of lamp body so that colourcaps and lamps shall be replaceable from the front of the panel. Two sets ofspecial tools, if required for replacing bulbs and covers shall also beincluded in the scope of supply. All colour covers shall be similar andinterchangeable and all lamps be of same type and ratings. Lamps andcolour caps shall be furnished 20% in excess of the actual numbersrequired.

2.3.12.3 The corresponding red green breaker position indicating lamps shall flashfor condition of discrepancy between the last operation of the circuit


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breaker (ON or OFF) and become steady when the switch is operated tocorrespond with the position of the circuit breaker. The discrepancysignal when the breaker is tripped shall also be followed by the soundsignal.

2.3.12.4 The wattage and resistance of lamps shall be as follows:

a) 220V, 5 to 10 W, 4000 to 8000 Ohms. with series resistor.

The indicating lamps with resistors shall with-stand 20% of rated voltageon a continuous basis.

2.3.13 Annunciators

On each control panel, 6 way" Annunciator shall be provided. Theannunciation scheme shall be of solid state type Lamp test/Accept/Resetpush buttons shall be provided for each "Annunciator".

2.3.14 Space Heaters

Tubular space heaters of adequate capacity and suitable for connection tosingle phase, 240 V, 50 Hz A.C. supply shall be provided inside eachpanel to prevent condensation of moisture on the wiring and panelmounted equipment when the panel is not in operation. These shall not bemounted close to the wiring or any panel mounted equipment. Heaters shallbe complete with isolating switches, HRC fuse on phase and link on theneutral of the heater supply and its switching shall be controlled by athermostat. Minimum size of the cable used for heating circuit shall be 4

mm. sq.

2.3.15 Test Blocks

Test blocks shall be provided on the panels. These shall be of the backconnected, semi-flush-mounted, switch board type with removablecovers. All test blocks shall be provided with suitable circuit identification.The cases shall be dust tight and shall have a black finish. Test blocks shallbe rated not less than 250V,10 amperes, and shall be capable ofwithstanding a dielectric test of 2500 V, 50 Hz for 1 minute. All test blocksshall be arranged to isolate completely the instruments from the instrument

transformers and other external circuits so that no other device will beaffected. Means shall be provided for testing either from an external sourceof energy or from the instrument transformers by means of multiple testplugs. The test blocks and plugs shall be arranged so that the currenttransformer secondary circuits cannot be open circuited in any positionwhile the test plug or cover plugs are in place, being inserted, or beingremoved. 6 Number each of test plugs which are to be used with the teststuds shall be supplied free with the main equipment.

2.3.16 Push Buttons

Push buttons shall be momentary contact type with rear terminalconnection. These shall be suitably shrouded to prevent inadvertentoperation. Integral inscription plates engraved with their functions shall beprovided.


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All push buttons shall have two normally closed and two normally opencontacts comprising rivets of pure silver. The contacts shall be able tomake and carry 5 Amp. and break one ampere inductive load at 220 VD.C. 10% spare push button shall be supplied with the panels. A redfilter shall be provided in each reset push button to provide an intensered colour when illuminated.

2.3.17 Interior Lighting and Receptacles

Each panel shall be provided with a 40W fluorescent lighting fixture ratedfor 240 volts, single phase, 50 Hz supply for the interior illumination of thepanel during maintenance. The fittings shall be complete with switch fuseunit and switching of the fittings shall be controlled by the respective paneldoor switch. Ballast shall be rated at not less than 0.9 power factor. Asingle pole 20 Amp. "T" rated lighting switch shall be provided for eachpanel, flush mounted on the left end. One duplex 240 V, 5A convenienceoutlet along with switch shall also be provided inside each door or pairs of

doors inside each cubicle. The lighting and convenience outlet circuitshall be completely wired in conduit and terminated on cubicle terminalblock.

2.3.18 Fuses and Switches

Each control panel shall be provided with necessary arrangement forreceiving, distributing, isolating and fusing of D.C. and A.C. supplies forvarious control, signaling, lighting and space heater circuits. Theincoming and sub-circuits shall be separately provided with switch fuseunits. Selection of the main and sub-circuits fuse ratings shall be such

as to ensure selective clearance of sub-circuits faults.

All fuses shall be HRC cartridge type conforming to IS-2208 mounted onplug in type fuse bases. All accessible line connection to fuse bases shallbe adequately shrouded. Fuses shall have operation indicators forindicating blown fuse condition. Fuse carrier base shall have imprints ofthe fuse rating and voltage.

2.3.19 Equipment Earthing

All metallic cases of relays, instruments and other panel mounted

equipment shall be connected to the earth bus by independent copperwires of size not less than 2.5 sq.mm. The colour of earthing wires shall begreen. Earthing wire shall be connected on terminals with suitable clampsconnections and soldering shall not be permitted.

VT and CT secondary neutral or common lead shall be earthed at oneplace at the terminal blocks where they enter the panel. such earthing shallbe made through links so that earthing may be removed from the groupwithout disturbing continuity of earthing system for other groups.

2.3.20 Supporting Steel

All necessary embedded leveling steel, sills, anchor bolts, channels andother parts of supporting and fastening of the panels and vibrationdamping pads shall be supplied by the bidder. Embedded parts with


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detailed instructions shall be delivered in time to meet the schedule forinsertion in the building structure.

2.3.21 Earthquake Condition

Under the seismic conditions, 24kV switchgear panels and other controlpanels shall be expected to behave as below:

i) The physical alignment of 24kV switchgear panels along withincoming and outgoing feeder connection supporting insulators andstructures of bus bars shall not get disturbed and there shall not beany internal flashover and or electrical fault.

ii) All relays, transducers, indicating instruments, devices in switchgearpanels shall not maloperate. Current carrying parts, supportingstructures, earth connection etc. shall not get dislocated and or shallnot break or distort.

2.4 24 kV SF6 CIRCUIT BREAKERS

2.4.1 General Requirements

2.4.1.1 The circuit breaker shall be of SF6 type suitable for indoor installation. Thebreaker shall be best and modern in design and shall be supplied with allthe associated equipments including fittings and wiring etc. Thebreaker shall be suitable for three phase auto re-closing operation.

2.4.1.2 The breaker compartment of the cubicle shall be designed to have fully

draw out self contained truck arrangement with breaker mounted on thesame.

2.4.1.3 The circuit breaker shall be provided with rapid and smooth interruptionof current under all conditions completely suppressing all undesirablephenomenon even under the most severe and persistent short circuitconditions or when interrupting small leading and lagging currents. Thedetail of any device or special feature incorporated to limit or control therate of rise of re-striking voltage across the circuit breaker contact shall bestated. The over-voltage caused by the circuit breaker switching oninductive and capacitive load shall not exceed 2.5 times the normal phase

to neutral voltage. The total break time for the circuit breaker throughoutthe range of its operation duty shall be stated in the tender and itshall be guaranteed.

2.4.1.4 All parts of the circuit breaker unit shall be mechanically designed towithstand all mechanical, electrical and other stresses which may beexperienced in the operation of the unit including those under shortcircuit conditions.

2.4.1.5 The circuit breaker shall be practically maintenance free over:

- a period of at least 10 years

- 100 switching operation at full breaking capacity

- 30,000 switching operation at no load


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- 20,000 switching operation at normal load

2.4.1.6 The breaker shall be reasonably quiet in operation.

2.4.1.7 The interrupter shall be sealed for life with fluarc sealing as per IEC studygroup 17A Dec.1981, Type-III.

2.4.1.8 Vacuum Circuit Breaker

The circuit breaker shall comprise of three vacuum interrupters, one for eachphase, each housed in separate ceramic enclosure for better electrical andmechanical properties. The three identical poles shall be mounted on acommon base frame and contact system of these poles shall bemechanically linked to provide three pole gang opening/closing for all typesof electrical faults. Each pole of the breaker shall be provided with vacuuminterrupter sealed for life encapsulated by ceramic insulator and shall be

interchangeable. The mechanical parts and linkage shall be robust andmaintenance free over at least 30,000 operation except lubrication ofpins/articulated joints at intervals of 5 years or 5,000 operations. Partsrequiring maintenance shall be easily accessible without requiring extensivedismantling of adjacent parts.

2.4.1.9 Sulphur Hexaflouride(SF-6)Circuit Breakers

The circuit breakers shall be of Sulphur Hexafluride (SF-6) gas filled,single pressure puffer sealed tank type suitable for indoor duties. Eachpole of the circuit breaker shall have an interrupting chamber filled with

SF-6 gas encapsulated in porcelain insulator housing independent of theother two poles. The gas pressure shall be monitored and regulated bysuitable pressure switches. The design and construction of the circuitbreaker shall be such that there is minimum possibility of gas leakageand ingress of moisture, there should not be any condensation of SF-6 gason internal insulating surfaces of circuit breaker. Suitable sealingarrangement shall be provided on each static joint to have proper sealingof SF-6 gas. An alarm shall be given if the gas density fails to a pre-setvalue and if it falls further to a specified minimum the breaker shall beblocked. The material used in the construction of circuit breaker shall befully compatible with SF-6 gas. All similar parts including poles of the circuit

breaker shall be interchangeable.

2.4.1.10 Sulphur Hexaflouride Gas(SF-6)

Sulphur Hexaflouride(SF-6) should be gaseous at normal room temperatureand pressure with a density of 6.16 g/litre at 20 degree C and 760 torr. Itshould be pure, colourless and non toxic. It should have good arcquenching property with high di-electric strength. The SF-6 gas should beinactive to material and upto 180 degree C temperature its compatibilitywith materials used in electric construction should be similar to that ofnitrogen. Breakdown products caused due to discharge in equipmentshould be compatible with constructional materials. Moisture contents ofthe gas should not be more that 15 ppm by mass. The SF-6 gas shouldgenerally conform to IEC publication 376-1971 or the latest amendmentand shall meet the requirement as per IEC.


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2.4.2 Operating Mechanism

The operating mechanism shall be capable of giving specified duty of thebreaker (sequence of opening and closing) as specified under clause 2.17(O-0.3-Sec-CO-3-min-CO). The breaker shall also pass the operational testwhich ascertain the capabilities of operating mechanism. The motorcompressed spring mechanism shall consist of a closing spring whichis wound or compressed by an electric motor immediately after thebreaker closes. The closing action shall also wind or compress a trippingspring and shortly after the breaker is closed both springs shall bewound. After the breaker has tripped, the tripping spring shall remain inthe released position as long as the breaker is open, but the closing springshall remain wound and ready for closing operation. The operatingmechanism shall have all the necessary auxiliaries, apparatus for operationand supervision, like motor starter with thermal overload release, oneclosing coil, two trip coils, push button for local electrical operation, pushbutton for direct mechanical tripping auxiliary switches, anti pumping

contactors, operation counter, socket for inspection, lamp and heater withswitch. In addition mechanical interlocking system for interlockingwith other associated breaker shall be provided. Details of operationlogic and other interlocking scheme is given under Clause No.2.10.2.Spring charging motor shall be standard single phase motor suitable foroperation on 240 V A.C. supply. Provision shall also exist for onedetachable handle for manual charging in the event of failure ofauxiliary supply. The mechanism shall be suitable for remote operations.In addition auxiliary local operating mechanism shall be trip free.

i) Operating voltage for closing/tripping coils shall be 220 VDC. The

D.C. supply shall be available in the sub-station.

ii) Operating voltages for spring charging motor and heater elementsshall be 240 VAC, 50 Hz. A.C. supply which shall be madeavailable at site.

2.4.3 Fixed and Moving Contacts

2.4.3.1 The fixed and moving contacts of the breaker shall ensure full contactduring closing. The contact metallurgy and geometry shall be such as toenable it to conduct the rated current and short circuit current with

minimum of contact burning and wear. Main contact shall have ample areaand contact pressure for carrying rated current and rated short timecurrent without excessive temperature rise. The contact material should beeither chromium, or some other suitable material. The main contact shouldhave low contact resistance and the mili-volt drop across the breakercontact should also be furnished along with the bid.

2.4.3.2 The breaker contact shall be designed such that diameter of thecontacts and their stems are optimally matched to those of arc chamberand insulator. Contacts shall be such that arc does not remain stationary butkeeps travelling by its own magnetic field.

2.4.4 Interrupter

2.4.4.1 Each pole of circuit breaker shall be provided with a SF6 interrupter sealedfor life and encapsulated by ceramic insulators. The interrupter shall be


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provided with steel chromium arc chamber to prevent vaporized contactmaterial being deposited on the insulating body. A further shield givingprotection to the metal bellow shall be provided. The metal bellows shallfollow the travel of the moving contacts to seal the interrupter against thesurrounding atmosphere.

2.4.5 Recovery Voltage and Power Factor

The circuit breaker shall be capable of interrupting rated power with powerfrequency recovery voltage equal to the rated maximum line to line servicevoltage at rated frequency and at a power factor "equal to or not exceeding0.15" as per IEC 56-1987. In case of multiple break circuit breaker,devices/method adopted to all the breaks shall be indicated and actualvoltage distribution recorded during interruption tests shall be furnishedwith the bid.

2.4.6 Restriking Voltage

The breaker shall be suitable to withstand required Rate of Rise ofRecovery Voltage (RRRV) & Transient Recovery Voltage (TRV) peak. Thecomplete data for the phase factor, amplitude factor, etc. for the rate ofrise of re-striking voltage shall be furnished in the tender.

2.4.7 Transformer Charging Circuit Breaking Capacity

The breaker shall be capable of interrupting inductive currents, suchas those occurring while switching off unloaded transformers, withoutgiving rise to undue over voltage and without re-strikes. The maximum

over voltage value, which will not be exceeded under such conditions shallbe stated in the tender.

2.4.8 Shunt Capacitor Switching Capacity

The maximum rating of single bank of shunt capacitors which can beswitched by the circuit breaker without re-strikes shall be stated in thetender along with over voltage occurring during such switching.

2.4.9 Automatic Rapid Re-closing

The circuit breaker shall be suitable for three phase rapid auto re-closingduties. The dead time of the breaker shall be adjustable and thelimits of adjustment shall be stated in the tender.

2.4.10 Out of Phase Switching

The circuit breaker shall be capable of satisfactory operation even underconditions of phase opposition that may arise due to faultysynchronisation. The maximum power that the breaker cansatisfactorily interrupt under "Phase Opposition" shall be stated in the bid.

2.5 TEMPERATURE RISE

The maximum temperature attained by any part of the equipment whenin service under full load condition should not exceed the maximumspecified value in the IS/IEC.


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2.6 INSULATORS AND HOUSING

The basic insulation level of insulating supports shall be as specified in thegeneral technical particulars in this specification. The porcelain usedshall be homogeneous, free from cavitations and other flaws. Theinsulators shall be designed to have ample insulation, mechanically strongand rigid for satisfactory operation under climatic conditions of the site.Minimum clearance between phases, between live parts and ground objectshall be as per IS-3072-1975 and should conform to Indian ElectricityRule-1956. The clearances etc. should be corrected for altitudes as perIEC/IS.

In order to avoid break down at extremely low pressure the supportinsulators should not be covered by moisture and dust. Insulatorsshould therefore, be extremely clean, free from sharp contours inconducting parts to avoid breakdown of the insulator and should have anti-

tracking properties. The insulators shall be capable of withstanding seismicacceleration of 0.5g in horizontal direction and 0.5g in vertical direction.

2.7 TRIPPING COILS

The circuit breakers shall be provided with two trip coils and one closingcoil. First trip coil shall be utilized for tripping the breaker on faultdetection, whereas second trip coil shall be used to trip the breaker whenfirst trip coil fails to trip the breaker and backup protection comes intooperation. Moreover, second trip coil shall be used to trip the breaker oncommand. The trip coils shall be suitable for pre-closing and after closing

trip circuit supervision.

2.7.1 TRIP FREE FEATURES

When the breaker has been instructed to close by manual instructions bypushing of push button, the operating mechanism will start operating forclosing operations, if in the meantime a fault has taken place and relaycloses the trip circuit of the breaker. The trip free mechanism shall permitthe circuit breaker to be tripped by the protective relay even if it is underthe process of closing. An anti-pumping device to prevent the circuitbreaker from re-closing after an automatic opening when the device initially

closing is maintained in the position for closing should be provided.

2.8 ACCESSORIES

2.8.1 Each circuit breaker assembly shall be supplied with the followingaccessories.

i) Line and earthing terminals.

ii) Control housing with:-

a) One auxiliary switch with adequate number of auxiliarycontacts, but not less than 20 nos. (10NO+10NC) for eachbreaker. These shall be over and above the No. of contactsused for closing, tripping and "reclosing" and interlockingcircuit of the circuit breaker. All auxiliary contacts shall be


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capable of use as "Normally Closed" or "Normally Open"contacts. Special auxiliary contacts required for the reclosingcircuit, if any, shall also be provided. There shall be provision toadd more auxiliary contacts at a later date, if required.

b) Operation counter.

c) Position indicator (Close/Open).

d) Necessary cable glands.

e) Fuses.

f) Manual trip device and local test push buttons.

g) Terminal blocks and wiring for all control equipment andaccessories.

h) Adequate number of heaters for continuous operation toprevent moisture condensation in the housing of operatingmechanism.

i) Spring charged indicator.

All parts of the breaker shall be easily accessible for inspection andmaintenance. Not only the main insulator, connections, joints etc. shallbe accessible but also adequate access shall be there for the auxiliaryequipment like secondary plugs, sockets, switches, and release coil and

terminal boards.

2.8.2 Complete set of robust mechanical interlocks shall be provided to safeguardagainst incorrect operation of the breaker. The minimum interlocks will be asfollows:-

a) The truck cannot be moved from either test to Service position orvice versa, when the circuit Breaker is "ON".

b) The circuit breaker cannot be switched "ON when the truck is in anyposition between test and Service position.

c) Front part of the truck cannot be removed when the Breaker is in"ON" position.

d) The low voltage plug and socket cannot be disconnected in anyposition except test/isolated Position.

e) The truck cannot be moved inside the panel, when the LT plug andsocket is disconnected.

In addition to above interlocks, the following safety Devices shall beprovided:-

a) Circuit breaker & sheet metal enclosure should be fully earthed.


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b) Self locking shutters should be provided which should closeautomatically when the truck is withdrawn to "TEST POSITION".

2.9 POWER CABLE TERMINATIONS

2.9.1 All cables, incoming and outgoing shall enter the equipment either throughrear/bottom or top of the Panels, decision to this effect shall be taken at thetime of final engineering of the drawings of equipments and its layout.Construction drawings for cable entry showing cutouts to be provided inthe floor shall be supplied by the bidder. Upto one number three core,22kV aluminium conductor XLPE power cable of 95 mm2 with theirstress cones are envisaged to be connected to the lower CT busconnector in case of incoming and out going cables from 22kVswitchgear. Provision shall be made in the CT and cable terminationchamber for connecting these cables.

All necessary cable terminating accessories such as Epoxy/Heat

shrinkable cable jointing kits, gland plates, supporting clamps andbrackets hardware shall be provided for cable. Tenderer shall ensurethat sufficient space is provided for entry and exit of all cables. The glandplates shall be of removable type and shall cover the entire cable alley.Glands shall be insulated where required.

2.9.2 Each group of bus bars and feeders spouts should be fitted withautomatically operated safety shutters. The appropriate shutter shall bepositively opened or lowered, for testing and inspection, each shuttershould be separately hand operated from the front of the unit and shouldbe latched either in open or in closed position but should be

padlocked/closed for maintenance purpose.

2.10 CONTROLS

2.10.1 The 24 kV, 6 No. Switchgear Panel Boards shall be controlled locallyfrom the sub-station where the switchgear is housed. Provision shall also bemade for remote operation from the main control room. Provision forremote "ON/OFF" operation and indications shall also be provided. Localcontrol devices, selector switch and position indicator shall be located inthe panel. The circuit breaker control scheme shall incorporate trip circuitsupervision arrangement. Local/remote selector switch shall be provided

for all the breakers for selection of Local control/Remote controlMechanical indicator, to show the "open" and "close" position of thebreaker shall be provided in a position where it will be visible to a manstanding on the ground.

2.10.2 OPERATION LOGIC AND INTERLOCKING

2.10.2.1 The operation logic of the 24 kV breakers housed in sub-station is asfollows and necessary interlocking between these breakers are to beprovided by the bidder. Necessary interlocking details/drawings should begot approved from the purchaser's before manufacturing as persingle line diagram.

(i) The breaker 52 HT-1 and 52 HT-3 will remain in "ON" conditionsif they are getting continuous supply from respective 22 kV linefeeder and keep 52 HT-2 in "OFF" position.


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(ii) In case 22kV supply from Kotla sub-station fails then breaker 52

HT-1 will be in open condition i.e. "OFF" and all other breaker i.e.52 HT-2, 52 HT-3 will be in "ON" position.

(iii) If in case supply from 22 kV local feeder fails then its associatedbreaker 52 HT-3 will be in open condition i.e. "OFF" and remainingbreakers i.e. 52 HT-1 and 52 HT-2 will be closed i.e. in "ON"condition.

2.11 BUSBARS

All the switchgear panels shall be provided with high electrical gradealuminium bus bar having continuous current rating of 630 Amps. Thethree phase bus bars shall be fixed in suitable configuration to minimiseelectro-mechanical stresses under short circuit conditions. All the busbar joints shall preferably be silver plated.

Inter panel insulating barriers shall be provided between bus bars ofdifferent units. The arrangement of bus bars shall be such as to providefacility for ready extension to additional units on either side. All bus barand jumper connection shall be of high conductivity alluminium alloy ofadequate size. The bus bar shall be rated as below:

1. System voltage rating of bus bar 24 kV

2. Continuous current rating 630 A

3. Symmetrical breaking current 12.5 kArating for 3 seconds

4. Rated peak short time current 2.5 times symmetricalin kA breaking current

The cross section of the bus bar shall be uniform throughout its runand shall be adequately supported and braced to withstand stressescaused at the time of short circuit. Each phase shall be provided withseparate support of non-hygroscopic, non-combustible, track resistantand high strength epoxy/fibre glass insulators. Where a common support

is provided anti-tracking barrier shall be provided between thesupports. All bus bar joints shall be provided with high tensile steel bolts,spring washer and nuts to ensure good contact at the joint. All the busbars shall be colour coded as per IS:375. The tenderer shall furnishcalculations along with the bid, specified current ratings. The minimumclearance in air between phases and phase to earth for entire run ofhorizontal and vertical bus bar shall be sufficient to withstand powerfrequency and impulse voltage withstand tests taking into consideration ofthe altitude correction factor.

The temperature rise of bus bar when carrying 90% of the rated currentalong its full run shall in no case exceed 55 degree C (above ambient)with silver plated joints and 40 degrees C with all other type of joints overand outside ambient temperature of 45 degree C.


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2.12 INSTRUMENT TRANSFORMERS

2.12.1 Current Transformer

2.12.1.1 The epoxy current transformers shall be mounted within the cubicles andshall conform in all respects to the latest edition of IS 2705 (Part-I, II, III)or the relevant IEC standards. Necessary structural steel brackets formounting these CTs shall be furnished. The technical particulars of CTs aregiven in clause 2.17 and in the single line diagram no. NJD(E)-528/06.

2.12.1.2 The current transformers shall have output and accuracy suitable for theinstruments and protection equipment provided. The accuracy class ofthe CTs shall preferably be 1.0 for the purpose of metering, for thepurpose of protection the accuracy class shall be 5P10 and PS. Theinstrument security factor for metering cores shall be less than 5. Therequirement of number of cores of CTs, their ratio burden and accuracyclass shall be as brought out in the schedule of requirement. Additionally,

the supplied CTs shall have the following rating also.

a) Rated continuous thermal current shall be 1.2 times the ratedcurrent.

b) Thermal short time rating for 3 second with the secondary shortcircuit the temperature rise of the CTs shall not exceed the limitsprescribed in IS/IEC.

c) Mechanical short time rating.

d) Class of insulation shall be of "Class E".

The current transformer must be capable of withstanding with secondaryshort circuited on full ratio a full off-set current having A.C. (symmetrical)component with an rms value of 12.5kA and crest value of 31.25kA.

2.12.1.3 The rated short time current of the CTs shall not be less than 12.5 kA for 3seconds.

2.132.1.4 The secondary winding of CTs shall be fully distributed around the core atall nominal taps. The actual exciting current upto the knee point voltage

shall not vary beyond the permissible standard from the normal excitingcurrent.

2.12.1.5 To avoid development of very high and dangerous over voltage in thesecondary windings of CTs due to inadvertent open circuiting of CTsecondary while normal current is flowing in primary winding, measuresshall be adopted to afford protection against this hazard by incorporatingsome device in the secondary circuit. The tenderer shall bring out indetails, the method proposed to be adopted to avert this eventuality.

All the routine test, type tests and tests at site shall be carried out oncurrent transformers in accordance with IS with upto date amendmentsthereof. The test to be carried out by the contractor shall clearly bestated in the tender in details. The bidder shall submit the magnetizingcharacteristics of current transformer along with the bid.


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2.12.2 Voltage Transformer

2.12.2.1 Voltage transformers shall conform to IS-3156 amended upto date orthe relevant IEC standards. Each transformer shall be complete with itsown high and low voltage HRC fuses and current limiting resistance, ifrequired. The fuses shall be so arranged that they can be readilyaccessible and can easily be replaced without shutting down anyequipment or dismantling the voltage transformer. Provision shall be madesuch that the primary fuses can be handled only in draw out positionwhen line is dead. The class of insulation shall be of "Class E". The othertechnical particulars of V.T. is given in clause 2.17.

2.12.2.2 The voltage transformer shall be arranged for connection to theincoming side and these shall be housed suitably in switchboard itself.

2.12.2.3 The output and accuracy of the instrument transformers shall satisfy theprotection and metering requirements. The bidder should indicate in his

offer, the actual burden imposed by relay meters, so that change if anyrequired in the rated burden of instrument transformer can be done at thetime of placing of orders.

2.12.2.4 All the routine test, type test and test after installation given in relevantIndian Standard shall be carried and tenderers are to give details of thetests which shall be carried out, with their offer.

2.13 INDICATING INSTRUMENTS

Indicating instruments shall be as called for in the schedule of

requirement. All instruments shall be mounted on the top of the cubiclein a separate compartment, suitably flush mounted type. Theinstrument case shall be dust proof, water tight, vermin proof andspecially constructed to adequately protect the instrument against damageor deterioration due to high ambient temperature and humidity.

The instruments shall be provided with all the auxiliary appliances andany special tools required for their maintenance. All the instruments shallhave dials pointers etc., designed to facilitate accurate reading byminimizing parallax and glare from the instrument window and byproviding clear and bold dial marking.

All instruments shall be designed for accurate measurement of thequantity or state under all conditions of operation and any error due tochange in ambient condition shall be kept to minimum.

Spring control instruments shall be provided with zero adjustment at thefront of the board capable of being safely handled while the instrument is inservice. The instrument shall be damped to comply with the requirementof clause 10.5 of IS-1248 or equivalent.

All the instruments shall comply with the requirement of first gradeinstrument of switch board type vide IS-1248 or equivalent standard. Allinstruments and meters shall be accurately adjustable and calibratedbefore shipment and shall have means for calibration, check andadjustment at site.


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The metric unit shall be used for marking the instrument dial. Theinstrument shall be capable of withstanding overall loads applied inaccordance with IS-1248. The instrument shall be capable ofwithstanding the following test, viz: effect of shock, vibration and humidity.

2.14 RELAYS

The relays shall be provided as called for in the schedule ofrequirement. Relay shall be of the static/electromagnetic type.

All the relays shall be suitable for operation over the range +10%/-20% ofthe nominal D.C. voltage of 220 V. The relays shall be designed to havethe minimum possible acquiescent drain on the batteries.

The relay should be designed to be secure against mal-operation for D.C.voltage dips, switch on, switch off and intermittent interruption of the powersupply. All the relays shall have different contacts for alarm and tripping. All

the relays should conform to IS-3231, IS-8714 and to IS-142 with upto dateamendments.

2.15 DRAWINGS

2.15.1 Successful tenderer shall submit the following drawings for approval:-

a) The general arrangements, overall dimensions and sectional viewsof each type of equipment and circuit breakers.

b) The detailed arrangement and sectional view of each type of

equipment, circuit breakers and cable boxes with dimensions.

c) The schematic diagram of connections of protection circuits alongwith the terminal details.

d) Descriptive data, literature and application data in respect of circuitbreakers and panels.

e) Descriptive data literature and application guide for current andpotential transformers.

f) Detailed dimensional drawings of switchgear panels showingequipment mounted on them along with the complete panel-wiselists of equipment and name plates.

g) Literature of equipments installed in the panels.

h) Detailed circuit diagram of 24 kV bus bar showing position of C.T. &P.Ts and the cable connection.

i) Outline drawings, mounting details, internal wiring diagrams, anditem-wise bill of material for all devices not located in tender'spanels but supplied loose by him with the boards.

j) Complete A.C. and D.C. schematic drawings of all elements ofcontrol and relay boards. These shall show all AC power


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connections and secondary connections for relays, meters etc.with vector relationship.

k) Complete schematic drawings for annunciation system.

l) Foundation drawings and floor plans of control and relay panels.Location of cable slots weight shall also be given on these drawings.

m) Panel inter-connection drawings indicating terminal block numbers,numbers of cores etc. where the connections have to be made.

n) The tenderer may submit any other drawings considerednecessary for installation and operation of the system inaddition to the drawings stated above.

2.15.2 Mistake in Drawings

The contractor shall be responsible for any discrepancies, errors oromission in the drawings or other particulars supplied by them whethersuch drawings, or other particulars supplied by them have beenapproved by the Engineer-in-Charge or not, provided suchdiscrepancies, errors or omissions be not due to inaccurate informationor particulars furnished to the contractor by the Engineer, but thepurchaser shall be responsible for the drawings and information suppliedby the Engineer and the purchaser shall pay for any alterations of thematerial or work necessitated by reason of inaccurate informationsupplied by the Engineer to the contractor. However, liability of contractorwould exclude payments towards any consequential losses/expenses

incurred by the purchaser arising from any incorrect informationsupplied by the contractor.

If any dimensions figured upon a drawing or plan differ from those obtainedby scaling the drawing or plan, the dimension as figured upon the drawingor plan shall be taken as correct.

All mistakes in drawings supplied by the contractor will be set right bythe contractor after obtaining approval of the purchaser.

2.16 TESTS

General

Standard Type test certificates as per the relevant standards to ensurethe quality and capability of the tendered equipments must be suppliedwith the bid documents. The bidder shall specify the details ofmeasurements and independent agency conducting these tests along withthe bid by Govt./NABL (National Accreditation Board for Laboratories)approved. In case the test certificates are not available actual tests will haveto be carried out on the equipments to be supplied in the presence ofpurchasers representative to his satisfaction.

All the tests to be carried out on all the equipment shall conform to relevantIEC, BS and Indian Standards.


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Equipment shall not be dispatched unless all the required tests arecarried out in the presence of purchaser's representative.

However, some of the tests which are to be carried out, are listed below:

The 24kV switchgear panel board shall be tested in the presence ofpurchaser's representative, for higher power frequency and lightningimpulse voltage values after applying altitude correction factor as perIEC-694.

2.16.1 Circuit Breaker

Type Test

Circuit breaker shall comply with requirements of type tests prescribed inIEC publication 56. Following type tests/reports as per stipulation of IEC-56/IS-13118 performed by Govt./NABL (National Accreditation Board for

Laboratories) approved shall be furnished with the offer.

i) Short time and peak withstand current test.

ii) Short time breaking capacity & making capacity.

iii) Single capacitor bank switching current capacity.

iv) Small inductive current breaking test.

v) Dielectric test i.e. power frequency withstand and Impulse withstand

test.

vi) Temperature rise test.

vii) Mechanical endurance test.

viii) Operational test.

Routine Test1. Operation test.2. Measurement of the resistance of the main circuit.

3. One minute power frequency voltage withstand test and Impulsewithstand test at voltage levels obtained after altitude correctionfactor as per IEC-694.

2.16.2 Potential TransformerType Test

Only type test, reports by Govt./NABL (National Accreditation Board forLaboratories) approved shall be furnished with the offer.

1. Verification of terminal marking and polarity.2. Power frequency test on primary winding.3. Power frequency test on secondary winding.4. Determination of error according to the requirement of the appropriate

accuracy.5. Temperature rise test.


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6. Impulse voltage test.

Routine Test

1. Verification of terminal marking and polarity.2. Power frequency test on primary winding.3. Power frequency test on secondary winding.4. Determination of errors according to the requirement of appropriate

accuracy.

2.16.3 Current Transformer

Type Test

Only type test, reports by Govt./NABL (National Accreditation Board forLaboratories) approved shall be furnished with the offer.

1. Verification of terminal marking and polarity.2. High voltage power frequency test on primary winding.3. High voltage power frequency test on secondary winding.4. Over voltage inter-turn test.5. Determination of errors according to the appropriate accuracy class.6. Short time current test.7. Temperature rise test.8. Impulse voltage test.

Routine Test

1. Verification of terminal marking and polarity.2. High voltage power frequency test on primary winding.3. High voltage power frequency test on secondary winding.4. Over voltage inter-turn test.5. Determination of errors according to the appropriate accuracy class.

Additional tests for measuring CT's

Type Tests

Only type test, reports by Govt./NABL (National Accreditation Board for

Laboratories) approved shall be furnished with the offer.

1. Accuracy test.2. Instrument security current test.

Routine Test

1. Accuracy test.2. Additional tests for protective current transformer.

A) For class - 10PType & Routine Tests

1. Current error and phase displacement test.2. Composite error test.


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B) For PS ClassRoutine Test

1. Knee point voltage.2. Exciting current.3. Secondary winding resistance.4. Turn ratio

2.17 TECHNICAL PARAMETERS FOR 24 KV INDOOR SWITCHGEAR

The technical particulars for the 24 kV Indoor SF6/Vacuum switchgearis given below:-

Sr.No. Description Values

A. Circuit Breaker1. Elevation Approx. 1062 meters.

2. Rated voltage (kV rms) 24

3. Rated frequency (Hz) 504. System neutral earthing system Solidly grounded

5. Type of arc quenching medium SF6 /Vacuum

6. Rated normal current at siteconditions (Amps)

630 A

7. Number of poles 3

8. Installation Indoor Type

9. Temperature rise As per IEC56/IS:13118

10. Rated short circuit:

a) Interrupting capacity

b) The percentage D.C.Component

12.5 kA at 24 kV

As per IEC 56/IS:13118

11. Rated short circuit makingcurrent (kA peak)

31.25 kA

12. First pole to clear factor 1.5

13. Rated short time withstand current 12.5 kA

14. Rated duration of short-circuit 3 sec.

15. Total break time for any current upto the rated breaking current withlimiting condition of operating and

quenching media pressure (ms)

< 80 ms

16. Rated peak withstand current 31.25 kA

17. Closing time ms


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breaker Above 125kV peak

21. One minute dry power frequencywithstand voltage

(i) to earth (C.B. closed)(ii) across terminal of open

circuit breaker

Values to be updated foraltitude of 1061 m as perIEC

Above 50 kV (rms)Above 50 kV (rms)

22. 10 sec. wet power frequencywithstand voltage

50 kV

23. Power available for mechanismoperating

Three phase 415V 50 HZor single phase 220 V

24. a) Rated supply voltage of closingand operating devices andauxiliaries

b) Permission voltage variation

c) Permissible frequency

i) 220Volts DCii) 240 V AC, 50 HZ singlephaseiii) 415 V, 50 Hz, three

phase

i) In case of D.C. powersupply voltage variationshall be between 80%to 110% of normalvoltage.

ii) In case of A.C. powersupply voltage variationshall be between -15%

to +10% of normalvoltage

+3%/-5% from normal 50HZ as per IS-2026 Part-I1977 Para 4.4.

25. Number of auxiliary contacts 10 NO & 10 NC oneach pole Continuouscurrent rating 10 AmpsD.C., breaking capacityshall be 2 Amps. with

circuit time constantless than 20 ms at 220Volts D.C.

26. Number of trip coils 2(Two) trip coils perbreaker.

B. Current Transformer1. Class of insulation E

2. Rated/Min power frequencywithstand voltage (rms valve)

50 kV

3. Rated lightning impulse

withstand voltage (Peak)

125 kV

4. Clear height of bushing As per latest IS/IEC

5. Minimum creepage distance As per latest IS/IEC

C. Voltage Transformer1. Class of insulation E


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2. Rated/Min power frequencywithstand voltage (rms valve)

50 kV

3. Rated lightning impulsewithstand voltage (Peak)

125 kV

4. Rated voltage factor As per latest IS/IEC

5. Clear height of bushing As per latest IS/IEC

6. Minimum creepage distance As per latest IS/IEC


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ANNEXURE-A

SCHEDULE OF REQUIREMENT FOR 24kV SWITCHGEAR

Sr.No.

Description Name of site whererequired

Qty.(No.)

Rate TotalAmount

1. 24kV Class IndoorType Switchgear asper specification andas per detail given inAnnexure-AA

a) Incoming Panel

b) Bus CouplerPanel

c) OutgoingPanels forTransformer:

Transformer HallCavern (Ref.Drg. No. NJD(E)-529/06 at Jhakri

2

1

2

Date: Signature of bidder

Name:Place: Status:

Whether authorized attorney oftendering companyName of tendering Company


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ANNEXURE-AA

SCHEDULE OF REQUIREMENT

24kV, 6 Nos. Switchgear Panel Board for Sub-Station.

24kV Switchgear Panel Board, totally enclosed, metal clad, floor mounting H.T.switchboard suitable for 22kV 3 phase, 3 wire, 50 c/s effectively earthed supply systemhaving a fault level of 12.5 kA at 22kV, complete in all respect including interlockingscheme to be installed and each equipped with the following:-

2 Nos. 24kV incomer panels 52 HT-1 and 52 HT-3 each comprising of:

1 - Metal clad housing with truck having integral circuit breaker with raising andlowering mechanism

1 - Set of mechanical interlocks

1 - Set of automatic safety shutters including locking/padlocking arrangements

6 - Isolation plugs and sockets

1 - Air insulated bus bar chamber complete with a set of 3 phase, 3 wire highelectrical grade aluminium bus bar of rating 630 Amps.

1 - 630 Amps normal current rating, triple pole circuit breaker SF6 /Vacuum having abreaking capacity of 12.5 kA at 24kV.

3 - 2 core air cooled current transformer 250-125/1A ratio having followingspecification:

Core-I Burden 15 VA(for protection) Class 5P

ALF 10

Core-II Burden 15VA(for metering) Class 1

ALF 10

3 - 5 limb withdraw able type voltage transformer having ratio 22/3kV/110/3/110/3 V, 30VA,Class 1.

1 - True trip free, manually/motor charged spring power closing mechanism withmechanical ON & OFF indication.

1 - Local hand trip device (electrical type).

1 - Spring return to neutral, pistol grip handle, 3 position, 6 pole breaker controlswitch ON-NEUTRAL-OFF.

1 - Semaphore indication

1 - Set of mimic in live green colour paint

1 - Set of AC and DC bus bar


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1 - Set of HRC fuses

1 - Set of indicator

1 - Earth bus bar 25x6mm copper

2 - Shunt trip coils suitable for 220 volts DC supply

1 - Close coil suitable for 220 volt DC supply

1- 240 V AC anti condensation strip heater complete with ON & OFF 15A, toggleswitch and thermostat

1 - Cable termination box complete with glands etc. connecting 240 V AC, 220VDC supply, CT & PT secondaries

1 - Set of incomer feeder cable termination box with cable jointing kits and glands

suitable for XLPE cable of 3 core, 95 mm sq. with cable supporting clamps etc.

INSTRUMENT PANEL FITTED WITH:

1 - 96mm square flush mounting type moving iron spring controlled voltmeter operatedfrom VT secondary of 22000/3/110V/3having scale of 0-30 kV, with selectorswitch.

1 - 96mm square flush mounting type moving iron spring controlled, ammeter scaled 0-150/300 Amps, with selector switch.

1 - Red lamp for circuit breaker close position.

1 - Green lamp for circuit breaker open position.

1 - Amber lamp for abnormal condition.

1 - White lamp for indicating trip circuit healthy indication.

1 - Push button switch for testing trip circuit.

1 - Push button for alarm accept/reset function.

1 - Set of auxiliary switches with 10 NO & 10 NC contacts.

1 - Trip circuit supervision relay.

1 - P.T. fuse failure relay.

1 - DC supply supervision relay.

1 - Set of test terminal block for protective relay.

1 - Flush mounting type, two elements kWH meter suitable for 3 phase, 3 wireunbalanced load.

1 - Test terminal block for testing of kWH meter etc. 220V DC, 10 watt indication lampcomplete with series resistor.


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1 - Flush mounting type triple pole directional IDMT relay with two over current

element and one directional earth fault unit.

1 - Flush mounting type under voltage relays with suitable auxiliary relay.

1 - Auxiliary high speed tripping relay hand reset type.

1 - Set of annunciators.

1 Nos. 24kV Bus coupler panels 52 HT-2 each comprising of:

1 - Metal clad housing with truck having integral circuit breaker with raising andlowering mechanism.





1 - 630 Amps normal current rating, triple pole SF6/Vacuum circuit breaker having abreaking capacity of 12.5 kA at 24kV.

3 - 2 core air cooled current transformer 250-125/1A ratio having following

specification:


ALF 10

Core-II Burden 15VA(Spare) Class 5P

ALF 10

1 - True trip free, manually/motor charged spring power closing mechanism with

mechanical ON & OFF indication.



1 - Semaphore indication.






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1 - 240 V AC anti condensation strip heater complete with ON & OFF 15A, toggleswitch and thermostat



1 - 96mm square flush mounting type moving iron spring controlled, ammeter scaled 0-150/300 Amps, with selector switch.











1 - Flush mounting type triple pole non-directional IDMT relay with two over current

element and one earth fault unit.


1 - Set of annunciators.

2 Nos. 24kV outgoing feeder panels 52 HT-4 and 52 HT-5 for 2.5 MVA transformercontrol each comprising of:

1 - Metal clad housing with truck having integral circuit breaker with raising andlowering mechanism.




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1 - 630 Amps normal current rating, triple pole SF6 /Vacuum circuit breaker havingbreaking capacity of 12.5 kA at 24kV.

3 - 2 core air cooled current transformer 250-125/1, 250-125/.577A ratio havingfollowing specification:


ALF 10

Core-II Class PS(for Xmer diff. Knee Point Voltage > 200 Volt

protection) Magnetising current < 30 mA at VK/4

1 - True trip free, manually/motor charged spring power closing mechanism withmechanical ON & OFF indication.



1 - Semaphore indication








1 - 240 V AC anti condensation strip heater complete with ON & OFF 15A, toggleswitch and thermostat


1 - Set of outgoing transformer feeder cable termination box with cable jointingkits and glands suitable for XLPE cable of 3 core, 95mm sq. with cable supportingclamps etc.


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1 - 96mm square flush mounting type moving iron spring controlled voltmeter operatedfrom VT secondary of 22000/110/3/110V/3 having scale of 0-30 kV, with selectorswitch.

1 - 96mm square flush mounting type moving iron spring controlled, ammeter scaled0-150/300 Amps, with selector switch.











1 - Flush mounting type triple pole non-directional IDMT relay with two over currentelement and one earth fault unit.


1 - Set of annunciators

1 - Differential Relay


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SCHEDULE-AB

SCHEDULE FOR ERECTION, TESTING & COMMISSIONING OF 24 KV SWITCHGEAR

Sr.No.

Description Qty.(No.)

Rate Total Amount

1. 24kV Class Indoor TypeSwitchgear as per specificationand as per detail given inAnnexure-AA

a) Incoming Panel

b) Bus Coupler Panel

c) Outgoing Panels forTransformer:

2

1

2

Date: Signature of bidderName:

Place: Status:Whether authorized attorneyof tendering companyName of tendering Company


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SCHEDULE-A-I

SCHEDULE OF TECHNICAL DEVIATIONS

Sl.No.

Vol.No.

Clause No. PageNo.

Deviation/ Variation Extra price to be paid incase deviation is requiredto be withdrawn by thebidder

Bidders Guarantee:

We guarantee that the above deviations in no way shall adversely affect theperformance and other requirements of the equipment stipulated in the specifications.

Date: Signature of bidderName:

Place: Status:Whether authorized attorneyof tendering companyName of tendering Company


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SCHEDULE-A-II

SCHEDULE OF TECHNICAL DATA PARTICULARS OF 24 kV SWITCHGEAR

(To be filled in by the tenderer with the bid)----------------------------------------------------------------------------------------------------------------------Sr.No. Description----------------------------------------------------------------------------------------------------------------------

A. PANEL DETAILS

1. Type designation2. Standard adopted3. Degree of protection provided

a) Main enclosureb) Within cubicle

4. Size of panel (WxDxH)mm5. Thickness of sheet steel

a) Front mmb) Back mmc) Sides mmd) Top mme) Any other mm

6. No.of compartments

7. Type of circuit breaker

8. Whether draw out or not

9. Rated voltage of switchgear Volts

10. Max. continuous voltage of Voltsswitchgear

11. Power frequency withstand EL-1062 m & Above.(voltage kV/min)

12. Rated Impulse withstand EL-1062 m & Above.(kV Peak)

13. Short circuit withstand kAcurrent for 3 sec.

14. Power cable entry to the cubicle(Whether from rear bottom)

15. Control cable entry to the cubicle

(Whether from rear bottom)

16. Whether control cables routedthrough H.T. Cubicle


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17. Paint Shade

18. Type of paint used(Epoxy/Enamel/Power Coating)

19. No.of heaters per panel

20. Whether automatic safetyshutter provided

21. Whether integral/seperateearthing facility providedfor bus bar/cable earthing

22. Size and material of earth bus mm

23. Type and material of control

terminal provided (stud typeor otherwise)

24. Whether panels are of unit wiseconstruction

25. Whether extension on both sideswithout limitation possible

26. Material of bus bar

27. Size of bus bar

28. Whether joints are silverplated and if so thicknessof plating

29. Size and number of fastenersused for bus bar joint

30. Material used for fasteners

31. Current rating of bus bar

32. Current density adopted

33. Material for bus supportinsulator

34. Voltage class of support

35. Creepage distance ofbussupport insulator

36. Clearances (phase to phase/phase to earth)

37. Whether bus bars rated forshort time current


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38. Guaranteed number of

operation:

a) with no load currentb) with full fault current

39. Dynamic load to be transferredto foundation:

a) O-operation(Compressive)b) C-operation(Tensile)

40. Seismic level for which the switchgearbreaker is designed:

a) Horizontal acceleration

b) Vertical acceleration

41. Load requirement of each panel(AC and DC both)

B. CIRCUIT BREAKER

1. Name of the Manufacturer

2. Country of Origin

3. Manufacturer's type anddesignation

4. Class: Indoor

5. No. of Poles

6. Rated voltage(kV)

7. Standards applicable

8. Max. continuous voltage kV

9. No.of interruption at ratedcurrent

10. Whether separate test positionprovided

11. Whether indicator provided tomeasure contact wear

12. Weight of panel kg

13. Shipping details:

a) Dimension (WxDxH)mm


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b) Weight kg

14. Normal current rating

a) IEC conditionsb) Site conditions

15. Frequency in cycles per second

16. Breaking capacity:

a) Rated short circuitcurrent (A.C.Component)

b) % D.C. componentc) Asymmetrical breaking

current including D.C.

componentd) Is it possible to increasethe rupturing capacity at alater date

17. Making capacity inKilo-amperes (Peak)

18. Short time current rating for:

a) 1 second

b) 3 seconds

19. Total break time in milli seconds:

a) At 10% rated interruptingcapacity

b) At 30% rated interruptingcapacity

c) At 60% rated interruptingcapacity

d) At 100% rated interrupting

capacity

20. Breaker:

a) Opening time in milli-secondswith no current

b) Opening time in milli-secondsat rated breaking current

c) Arcing time in milli-secondd) Time in milli-seconds from

Arc Extinction to contactfully open

e) Dead time in milli-secondsfor single phase andthree phase reclosing


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f) Time in milli-seconds:

i) From circuit Energisedto contacts make

ii) From contact make tocontacts fully closed

21. Temperature rise in currentcarrying parts at rated currentand the maximum temperatureattained by any part over anambient of 40 deg. C.

22. Is the circuit breaker suitablefor rapid three phase autoreclosing.

23. 1.2/50 microsecond Lightning EL-1062 m and aboveImpulse withstand voltagein kV peak:

a) Between line terminal &ground (breaker closed)

b) Across terminals withcircuit breaker contactsopen

24. Data on restriking 100% 60% 30% 10%voltage rated rated rated rated

i) Amplitude factorii) Phase factoriii) Natural frequencyiv) Rate of rise of restriking

voltage kV/micro second

25. a) One minute power frequency EL-1062 m & Abovedry withstand voltage to

earth(in kV r.m.s.)b) One minute power frequency

wet withstand voltage toearth (in kV r.m.s.)

26. Out of phase switchingcapability of the breaker

27 Rated out of phasebreaking current

28. Rated operating duty cycle

29. Minimum clearance in air:

a) Between poles(mm)


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b) Between live parts(mm)c) Between live parts to

ground level (mm)

30. Creepage distance:

a) To ground (mm)b) Between terminals(mm)

31. Number of breaks in seriesper pole

32. Type of main contact

Documents

tec-spec-chap-A