Short Circuit and Coordination Anaylsis

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// Short Circuit and\;oordination Analysis

Glyn J. Lewis, P.E.

Applied Power

Redwood Shores, California

Glyn J Lewis, P.E. Applied Power2/28/2006

1

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2/28/20062

,

HV ahd MV Circuit Breakers/

• At\JSI C37.010

• are nominally rated in MVA.

• by symmetrical interruptingand withstand. Withstand isalways 1.6 current.

• Use K Factor for lower voltages than breakerrating.

Glyn J. Lewis, P E Applied Power

/SHORl/CIRCUIT ANALYSIS

,.eclosers and Fault/ Interrupters

• C37.60

opening asymmetrical current forclosing and withstand.

• X/R ratios vary b' size.

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Glyn J. Lewis, P.E. Applied Power2/28/2006

3

//SHORT/CIRCUIT ANALYSIS

Cutouts• A'SIC37.40/41/42/44/48

• based upon Symmetrical andcurrents.

• Maximum X/R"fatio is 15.

Glyn J. Lewis, PE Applied Powe2/28/2006

4

Mediu Voltage Switches andFuses

• ANSI C37.40/46/47

• symmetrical and asymmetricalamperes.

• Asymmetrical r:atings are 1.6 timessymmetrical ratin'g.

Glyn J. Lewis, PE Applied Power2/28/2006

5

/Mediu,n; Voltage Conductors

• 240-100

• Fuse protection is limited to 300% ampacityrating

• Relay pick seth g is limited to 600% ofampacity rating.

• Size or setting must pmtect cable against Fheating curve.

Glyn J. Lewis, PE. Applied Powe2/28/2006

6

/

/<• 450-3 and ANSI G57.1 09 for oil filled units

and C57.12.0 for dry type units.

• shown in NEG.

• Verify that primary protection protects againstshort circuit with'5tand and combination primaryand secondary proteds against thermalwithstand per ANSI Standards.

Glyn J. Lewis, P.E Applied Powe2/28/2006

7

SHORT ANALYSISLOWyOLTAGE SYSTEMS

AND POWER/CIRCUIT BREAKERS

• C37.13/16/20.1 and UL1558

• is rated in symmetrical amperes withderate for high X/R ratios over 4.9 for

"fused and 6.6 for unfused breakers. (VI'i;;V•. "'" 5t. t" tr {"<

• Derate applied to the calculatedsymmetrical can be as high as1.15.


8

CIRCUIT ANALYSISPANELBOARDS,

AND INSULATED CASE< BREAKERS• EqbJipment rated in symmetrical ampereswith"d€rates for high X/R ratios.

• applied to the breaker ratingand can be"as low as 0.62 for X/R ratiosabove 20. Ca;eful consideration must begiven to where theX/R ratios are high.

Glyn J Lewis, P.E. Applied Powe2/28/2006

9

ANALYSISSWITCtlBOARDS, PANELBOARDS,MOL ED AND INSULATED CASE

BREAKERS

• Ttieze are serious limitations per UL489case and insulated caseapplied on ungrounded,

delta and high resistancegrounded systems.

Glyn J Lewis, P.E. Applied Powe2/28/2006

10

LOW VOLTAGE SERIES RATINGS

• Equipment can be rated with a line sidedevice. That is, a breaker of

higher"i, terrupting capacity or a fuse.

UL67 or NEG 110.22;

• Series tested com'tJlnations as listed ithe UL "Yellow BOOK' only apply.

Glyn J. Lewis, PE. Applied Powe2/28/2006

11

LOW' OLTAGE CONDUCTORS

• Use"ampacities from NEe Table 310-16 and

• Use 60 degree column for less than 125A.

• Use 75 for 125A and over.

• Up to 800A use trip equal or up.

• Over 800A use equal OF next size trip down.


12

/// LV FUSE

2128/2006Glyn J. Lewis, P.E. Applied Power 13

2/28/200614

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/ FUSE - FUSECOORDINATION

2/28/2006Glyn J Lewis, P.E. Applied Powe 15

2/28/200616

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/ FUSE-BREAKERCOORDINATION

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2/28/2006Glyn J. Lewis, PE Applied Power 17

2/28/200618

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MOLDED CASE BREAKER

2/28/2006Glyn J. Lewis, P.E Applied Power 19

2/28/200620

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COORDINATION

2/28/2006Glyn J Lewis, P.E. Applied Powe 21

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lle at 2QC

2/28/200622

//

///POWER CIRCUIT

BREAKER

2/28/2006Glyn J. Lewis, P.E. Applied Power 23

2/28/200624PAGE 12C OF

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/MEDIUM VOLTAGE\ FUSE(),HARACTERISTICS


2/28/200626

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COORDINATION


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2/28/200628

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COORDINATION

2/28/2006Glyn J. Lewis, PE. Applied Power 29

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2/28/200630

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/COORDINATION

SOLID STATE

2/28/200632

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5ul 1"-- -,1-' I,__+-_+ --j__j-__j-.;;ClHIVE8 ! l\8 PREVIOUSLYilUr- EFCRTBED.·

PlJ NOTE.. I THAT, IPROVIDE --

SEfECTivE TRrPPIN1·CLOSER D THAN

DUE TO

//

//

// RELAY-FUSECOORDINATION


2/28/200634i'lI.OE 01' 20t'

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2/28/2006Glyn J. Lewis, P.E. Applied Powe 35

//

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/.v GROUND RELAYCOORDINATION

2/28/200636

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/DESIGNING

/ FOR/ COORDINATION

ANDSEL "CTIVE TRIPPING

2/28/2006Glyn J. Lewis, PE. Applied Power 37

2/28/200638

TTLACK OF SELECTIVE TRIPPING

WITH G. F. RELAv

//

.7ADD• I ,r-••----I

v "1 (

T

c:;

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50 DEVICE TO BESET AT 1, 6 SYMSECONDARY FAULTCURRENT

MR t:-O-O50/51 50/5! N

T50/51 50/51 N

MRJ::-o-of 50/51 50151N

¢

MR

//

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LACK OF SELECTIVE TRIPPINGDUE TO INSTANTANEOUS ELEMENTS

V

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MR ::-0-050/51 50/51N

T

¢ k ¢J---OMR MR

51 51N 51 SIN 51 51N

DELETE INSTANTANEOUS TRIPS (IT)(IF POSSIBLD

UTILITY MAY FORCE USE OF IT'S

Glyn J. Lewis, PE Applied

t:;j" SIN

¢

T TLILU/LUUU

40

•51 SIN

MR MR MR50/51 SO/SiN

T50/51 SOISIN

T50/51 SOISIN

TADD DIFFERENTIAL PROTECTION

(UTILITIES WTLL ACCEPT THIS TN LIEU OF IT ON MAIN)

/MAIN) LSG

tDB

FEEDER) LSIG

TMAIN) LSG

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tFEEDER) LSG

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...... ':1" ............... , .... , ' ...... , .t-' ..... " ......... , ............ 'VWHAT ARE THE LI MITAT TONS OF TH I S SYSTEM? 00642

'06ZONE INTERLOCKING TO RESOLVE COORDINATION43

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MAIN )/LSG

DB tFEEDER }:SlGn_n __@0 1 SECS

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t t t)LS(]) )LS(]) )LS(])

_1 1 1-

ALL GENERATORS THE SAME SIZE,WHICH BREAKER TRIPS FOR A GENERATOR

ALL BREAKERS ARE SET THE SAME,Glyn J. Lewis, PE Applied powerV

/

1200644

FAUL 17

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G2

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ADD HS GENERATOR DIFFERENTIAL TOPROVIDE SELECTIVE TRIPPING,

DELETE IT OR SET HIGHER THAN ASYMMETRICALFAULT CURRENT FROM ONE GENERATOR,

Glyn J. Lewis, P.E. Applied

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2/28/200645

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Engineering

Short Circuit and Coordination Anaylsis