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Information contained in this Application Guide is based on established industry standards and practices.It is published in the interest of assisting in the preparation of plans and specifications for medium-voltage metalclad switchgear. Neither the General Electric Company nor any person acting on its behalfassumes any liability with respect to the use of, or for damages or injury resulting from the use of anyinformation contained in this Application Guide. This information in this guide does not supplement orreplace performance data contained in other product publications of the Company./

•: "\

v

Sections

DForeword

ESystem One-Line Diagram

\

ECircuit Breaker Selection

EControl Power Equipment

ESystem and Equipment Protection

J

/

\

Contents

Section 1Foreword

Page

USE OF APPLICATION GUIDE 2

POWER / VAC® BREAKER & SWITCHGEAR COMPONENTS 2

TWO-TIER BREAKER STACKING 3

MODULAR CONSTRUCTION 3

/

1

Foreword'S

USE OF APPLICATION GUIDE medium-voltage metalclad switchgear. Informationis provided relating to one-line diagrams, circuitbreaker ratings and selection, and control powerrequirements.This Application Guide provides information

necessary to help plan and specify medium-voltagepower system switchgear, using General Electric 'sPOWER/VAC® breaker. This guide is organized topresent the information in an orderly, step-by-step manner. Since it is intended to be a work-book, only the data necessary to choose applicableswitchgear is included,

Complete specifications can be written for mostswitchgear applications using this publication, asystem one-line diagram, and reference to appro-priate literature for guidance in calculating short-circuit currents or for other extensive technicalinformation beyond the usual scope of an applica-tion guide.The topics discussed in the sections of this guideare of a general nature, applicable to any type of

POWER /VAC BREAKER ANDSWITCHGEAR COMPONENTS

POWER/VAC breaker and switchgear componentsare designed for application on 5-kV, 7.2-kV, and15-kV power systems with available short-circuitcapacities from 250 through 1000 MVA nominal.POWER/VAC circuit breakers are rated per ANSIC37.06-1971, Table 2. Available ratings are shownon page 3-3 of this application guide.Switchgear components are designed, built, andtested to the applicable industry standards shownin Table '1-1.

Table 1-1. Applicable Industry StandardsAMERICAN NATIONALSTANDARDS INSTITUTE (ANSI)70 East 45th StreetNew York, New York 10017

NATIONAL ELECTRICALMANUFACTURERS ASS’N (NEMA)2101 L St, NW, Suite 300Washington, D.C. 20037

StandardStandard DescriptionDescriptionNo, No,

AG Power Circuit Breaker RatingStructureC37.04

High-voltage FusesSG-2Preferred Ratings of Power CircuitBreakersC37.06

Interrupting Factors — ReclosingServiceC37.07

SG-4 Power Circuit BreakersTest Procedure for Power CircuitBreakersC37.09

Application Guide for Power CircuitBreakersC37.010

Power Circuit Breaker ControlRequirementsC37.11 SG-5 Power Switchgear Assemblies

Switchgear Assemblies and Metal-Enclosed BusC37.20

C37.100 Definitions for Power Switchgear/

ei- v:]

2

Foreword6>

Specifically, OEM switchgear components incor-porate the following new basic design elements,compared to air-magnetic and early designs ofvacuum metalclad switchgear.• The steel skeleton frame offers two-tier POWER/

VAC® breaker stacking for application flexibilityand floorspace savings.

• The steel skeleton frame utilizes modular con-struction resulting in one basic vertical sectionsize, thus simplifying equipment planning andproviding installation savings.

These fundamental design improvements affectcertain elements in the switchgear, principally theone-line diagram and the arrangement of switch-gear units in a lineup. Since these application con-siderations are a result of the equipment design,a brief illustration of the switchgear componentdesign concepts is provided.

TWO-TIER BREAKER STACKING

Mixing and matching of a variety of unit typesand breaker ratings is possible using two-tier unitstacking. The nine standard combinations of upperand lower units are shown in Figure 1-2.

MODULAR CONSTRUCTION

Breakers and auxiliary devices can be accom-modated in the upper and lower breaker compart-ments as shown in Figure 1-3.

TYPICAL UPPER AND LOWER UNIT CONFIGURATIONSAVAILABLE UNIT COMBINATIONS

(1) Typical Breaker Units — 5/15 kV

Lower 1200A, 2000A or 3000A BKR.Upper 1200A or 2000A BKR.1200A1200A 1200ABkr. Bkr . Bkr .

E 3

=#1200A 2000A Aux. BKRBkrBkr. BKR

2000A Aux.Aux. Bkr. *Space for 4 CTS Per Phase, 2 on Upper Studs & 2 on Lower Studs

1200A 2000AAux. (2) Typical Auxiliary Units - 8/15 kVLower ; VT or CRTBkr. Bkr. Upper ; VT or CPT Alt. Lower : Puses Only

Roll-Aux. out

TrayAux. \ VT/CPT

3000A Aux.Bkr.Fuses for 3 0 CPT or1 0 CPT > 15 kVA.

VT Accommodations2 L-L {2 Fuses Each)3 L-N {1 Fuse Each)

CPT AccommodationsUp to 15 kVA 1 0 with 2 Fuses

Note: Above combinations for 3000A busmaximum*No breakers or roll out trays permitted here.

/Figure 1-2. Nine standard combinationsof upper and lower units.

Figure 1-3. Typical upper and lower unitconfigurations.

i•d_i>

3

f \ ;*l/-

/

1'

>:i:ti-ll-I

I4I h

Contents

Section 2System One-Une Diagram

Page

INTRODUCTION 6

6DEVELOPING A ONE-LINE DIAGRAM

8PRELIMINARY ONE-LINE DIAGRAM

PARTIALLY DEVELOPED ONE-LINE DIAGRAM 9

DEVELOPED ONE-LINE DIAGRAM 10

ADAPTING ONE-LINE DIAGRAM TO EQUIPMENT 12

14REFERENCES

/

5

System One-Line DiagramINTRODUCTION

The first step in preparing a specification formetalclad switchgear is to develop a one-linediagram. A one-line diagram (single-line) is "adiagram that shows, by means of single line andgraphic symbols, the course of an electric circuitor system of circuits and the component devicesor parts used therein”. (See Ref. 1 of this section.)When preparing switchgear one-line diagrams, usegraphic symbols in accordance with IEEE and ANSIstandards in References 2 and 3.

One-line diagrams employ device function numberswhich, with appropriate suffix letters, are used toidentify the function of each device in all types ofpartially automatic, fully automatic, and in manytypes of manual switchgear. A complete list ofsuch device function numbers is published inReference 4 and shown in Table 2-2.

DEVELOPING A ONE-LINE DIAGRAMTo illustrate the development of a one-linediagram, a typical resistance grounded system hasbeen chosen. The same general procedures wouldapply to solidly grounded distribution systems.Three steps are used in producing a one-linediagram: the preliminary diagram, followed by thepartially developed diagram, and finishing withthe developed diagram.The abbreviations used for the principal meters,instruments, and other devices (not includingrelaying, which is listed in Table 2-2), as found inthe application guide, are listed in Table 2-1.Each device in an automatic switching equipmenthas a device function number which is placed

adjacent to or within the device symbol on allwiring diagrams and arrangement drawings sothat its function and operation may be readilyidentified.These numbers are based on a system which wasadopted as standard for Automatic Switchgear bythe American National Standards Institute andappear in ANSI C37.2-1970, (See Ref. 4 of thissection.)Table 2-2 is a list of device numbers and functionsas taken from this standard.

Table 2-1. AbbreviationsAbbr. Description DescriptionAbbr.AM Ammeter

Ammeter switchAuxiliaryBreakerCut off switchControl power transformerControl switchCurrent transformerField ammeterFrequency meterGeneratorGovernor SwitchInduction motorPotential transformer

S Synchronous motorSurge arresterSynchronizing switchSynchroscopeSynchronizing bracketTest deviceVarmeter (one-line)Varmeter (device list)VoltmeterVoltage regulatorVoltmeter switchWatthour meterWatthour demand meterWattmeter

AS S/AAux SSBkr SYNCO SYN BRCPT TDCS VARCT VARMFA VMFM VRG VSGS WHM

WHDM/

PT WM

IKfJ:

6 );

Section 2Table 2-2. ANSI Standard Device Function Numbers

Dev. Dev.No. Function51 AC Time Overcurrent Relay52 AC Circuit Breaker53 Exciter or DC Generator Relay54 Reserved for future application55 Power Factor Relay56 Field Application Relay57 Short -Circuiting or Grounding Device58 Rectification Failure Relay59 Overvoltage Relay60 Voltage or Current Balance Relay61 Reserved for future application62 Time-Delay Stopping or Opening Relay63 Pressure Switch64 Ground Protective Relay65 Governor66 Notching or Jogging Device67 AC Directional Overcurrent Relay68 Blocking Relay69 Permissive Control Device70 Rheostat71 Level Switch72 DC Circuit Breaker73 Load-Resistor Contactor74 Alarm Relay75 Position Changing Mechanism76 DC Overcurrent Relay77 Pulse Transmitter78 Phase-Angle Measuring or Out-of -Step Protective Relay79 AC Recloslng Relay80 Flow Switch81 Frequency Relay82 DC Reclosing Relay83 Automatic Selective Control or Transfer Relay84 Operating Mechanism85 Carrier or Pilot -Wire Receiver Relay .86 Locking-Out Relay87 Differential Protective Relay88 Auxiliary Motor or Motor Generator89 Line Switch90 Regulating Device91 Voltage Directional Relay92 Voltage and Power Directional Relay93 Field-Changing Contactor94 Tripping or Trip-Free Relay95 \ Used only for specific appli -96 I cations in individual Installa-97 > tions where none of the98 i assigned numbered functions99 / from 1 to 94 are suitable.

FunctionMaster ElementTime-Delay Starting or Closing RelayChecking or Interlocking RelayMaster ContactorStopping DeviceStarting Circuit BreakerAnode Circuit BreakerControl Power Disconnecting DeviceReversing DeviceUnit Sequence SwitchReserved for future applicationOver-Speed DeviceSynchronous-Speed DeviceUnder-Speed DeviceSpeed or Frequency Matching DeviceReserved for future applicationShunting or Discharge SwitchAccelerating or Decelerating DeviceStarting-to-Running Transition ContactorElectrically Operated ValveDistance RelayEqualizer Circuit BreakerTemperature Control DeviceReserved for future applicationSynchronizing or Synchronism-Check DeviceApparatus Thermal DeviceUndervoltage RelayFlame DetectorIsolating ContactorAnnunciator RelaySeparate Excitation DeviceDirectional Power RelayPosition SwitchMaster Sequence DeviceBrush-Operating or Slip-Ring Short -Circuiting DevicePolarity or Polarizing Voltage DeviceUndercurrent or Underpower RelayBearing Protective DeviceMechanical Condition MonitorField RelayField Circuit BreakerRunning Circuit BreakerManual Transfer or Selector DeviceUnit Sequence Starting RelayAtmospheric Condition MonitorReverse-Phase or Phase-Balance Current RelayPhase-Sequence Voltage RelayIncomplete Sequence RelayMachine or Transformer Thermal RelayInstantaneous Overcurrent or Rate-of -Rise Relay

No.123456789

1011121314151617181920212223242526272829303132333435363738394041

/ 42434445I 4647484950

7

System One-Line Diagramm‘v-v

115 kV 60Mz5000 MVA S/C X /R» 0

115 kV 60Hz5000 MVA S/C X /R = 8

X&

AA12 /16/20 MVA 400 A tCZDHI» , 400 A OMVA12 /1

-< -<g0

Y !3.8 kV 13.8 kV<o>i i0 0 0T T T

INormallyOpen£ 0w. r\y

S )5000 HP 5000HP1.0 PFAA 1.0 PF

2.4 kV

5000kYA 400 A[

-<2.4kV

400 V

o4-1000 HP 4- I000HP5-100 HP 5 -100 HP

50-10 HP 50- 10 HP5- 100 HP50-10 HP

5-100 HP50-10HP

4 Substations 4 SubstationsFigure 2*1. Preliminary one-line diagram.

PRELIMINARY ONE-LINE DIAGRAM

breaker symmetrical interrupting capability.(See Ref. 3 of Section 3.)

— Determine the applicable circuit breakerratings.

— Compare the feeder cable short-circuit heatinglimit with the maximum available short-circuitcurrent times K - times K0. (See Ref. 10 and 12of this section.)

Note that the calculations performed in accord-ance with Reference 5 determine only medium-and high-voltage circuit breaker ratings. Performshort-circuit studies to determine relay operatingcurrents in accordance with procedures outlined inReference 6. For other than power circuit breakers,refer to the appropriate ANSI standard for short-circuit calculation procedure.

On this diagram (Figure 2-1) show:

— System voltage and major component ratings.— Major medium-voltage cable lengths, sizes, and

construction. (Not shown in example.)— Approximate number and ratings of ail motors.— Supply system available short-circuit capability

in symmetrical MVA (plus X /R ratio) or perunit R + jX (on a given base).

Using data on the one-line diagram, performshort-circuit calculations. (See Ref. 5 of this sec-tion.) From these calculations:— Compare the calculated “first cycle” (momen-

tary) asymmetrical current duty with the closeand latch circuit breaker capability.

— Compare the calculated “1-1 /2 to 4-cycle”(interrupting) current duty with the circuit

/

(r->

8

Section 2(

U5 KV 60 Hz5000 MVA S/C X/R =8 115 kV 60Hz

5000 MVA X /R = 8

o—||1 l|f 0

Short-Circuit at Each Main 13.8 kV Bus:1st Cycle — 12.4 Asym kA1-1/2 — 4 Cycles — 7.2 Sym kA

/ /I50/5;i!150/5

13.8 kV Breakers:Type VB-13.8*500,1200Ao

100/5125 V dc Control from Station BatteryI00/5! 3A 3A .. A\Zmft0MVA 200/5 . | 1|| I2VW20MVA Z - 6%200/5Z = 8% m -<400 A 400 A

j & yRevenueMetering Revenue

Metering

1200/5 1200/5£!/2s

*1'14,400-120 V I4.400-I20V21200/5 1200/51200/5 1200/5 MlN.O. 3D*-w-

3 T 13.8 KV 3I200A Bus 13.8 kV 1200 A Bus

400/5 400/5, 300/5 300/5 300/5 300/5 40(V5c±400/5,p. ' ,i-: 3£E3EE =cz

3^- —V - 31 33'V-:AA A /Nas

3?v V \y

pj||50/^jj50/;rjjf50/5 50/5m50/5 50/5I

SubstationFeeders

50/5, SubstationFeeders

©5000 HP

I.OPF5000 HP

I.OPF

Figure 2-2. Partially developed one-line diagram.

PARTIALLY DEVELOPEDONE-LINE DIAGRAM

Using the sample system, a partially developedone-line diagram is shown in Figure 2-2. On thisdiagram, the specifier should:— Show the results of the short-circuit calculations

performed, using the preliminary one-linediagram and selected circuit breaker ratings.

— Show ratings selected for external devices,such as grounding resistors, control powertransformers, and batteries.

— Select tentative current transformer (CT) ratiosin considering the maximum transformerratings, motor ratings, and ampacity of thecircuits involved, {See Section 5.)

— Locate current transformers and potentialtransformers, considering the type of protec-tive relaying instrumentation and meteringrequired.

/

’.r; •

9

System One-Line DiagramPM5 kV 60 Hz

5000 MVA S/C X/R = 8

|~o O—111 3 - Station TypeSurge Arrestors

/150/5

52hv v

100/53

iFpXr—12/16/20 MVA —f 200/5 40QA

ry-v-V\ . , /yiV... J i 3Z * 8% 10 SEC

l X/Revenue

Metering //

AM//1200/5 f ’3l- bb

513w>5IN

B I

1200/5 i«-3 v ":A3

oVMz z3 o O-J

[ 200/5

V-yvo'>400/5 I

1A

-©T- J50 /5 7M

'5000 HPI .0 PF

DEVELOPED ONE-LINE DIAGRAM

— Include in the study an examination of all cir-cuits for compliance with applicable local andnational codes. (See Ref. 11 of this section.)

— Verify that all circuit conductors are appliedwithin the conductor' short-circuit heatinglimit. (See Ref. 10 and 12 of this section.)

(General Electric, under special contract agree-ments, will perform power system studies,including the necessary calculations andcomparisons,)

A developed one-line diagram for the system isshown in Figure 2-3. in addition to the informa-tion shown on the partially developed one-linediagram, the specifier should:— Show all relaying, instrumentation, and metering.— Select relaying, instrumentation, and metering.— Confirm the selection of relay ratings and

characteristics by performing a completesystem short-circuit and coordination study.(See Ref. 7 through 10 of this section.)

/

V. ,;7

10

Section 2H 5kV 60 Hz

5000 MVA S/C X/R = 83- Statlon Type ||| cSurge Arrestors " /

- j 150/5- ' 3—+. 52^—yi—~

Or<t)i c - 3100/5/ *

^ j400A 200/5 I 2/I6/20MVA

rVYY>®r-- £ <H=1 I 2 = 8%\ 10 SEC6 JG

Nn 4slRevenuen Z\/ ( Meter ing

Im.

G JU' f

AM

1200/5“'3

WHWT-A/ARWWMWAS,

Va Vi Vi 6/ 1o o \

*1v

- ] 1200/5- J3

I 3.8 KVi:

400/5300/9 400/5 3AM

52 J?n»5CA / J50/5 GSI

Figure 2-3. Developed one- line diagram.5000 HP1.0 PF

PROTECTIVE RELAYS87TPhase Time & Instantaneous Overcurrent RelayQ-j Transformer Ground Differential Relay

Transformer Lockout Relay(51N) ®Residually Connected Time Overcurrent Relay

@ (87M)Ground Time Overcurrent Relay Motor Differential Relay

^86M)/Ground Sensor Instantaneous Overcurrent Relay Motor Lockout Relay

Phase Time Overcurrent Relay Motor Thermal & Instantaneous Relay

©Residually Connected Time Overcurrent Relay Undervoltage Relay

0High Speed Transformer Differential Relay 0,5 to 5 secondsTimer

11

System One-Line Diagram

ADAPTING ONE-LINE DIAGRAMTO EQUIPMENT

Figure 2-4 shows two possible arrangements oftwo-high metalclad switchgear as developed fromthe one-line diagram in Figure 2-3. Both savespace when compared to air-magnetic metalcladswitchgear, and both permit the addition offuture units on either end.The arrangements shown are not the only oneswhich can be developed to satisfy the conditionsof the one-line diagram.

/

12r >i-'W

Section 2ARRANGEMENT I

1ISYN. SYN.IN- IN-(FUTURE:) FEEDER FEEDER MOTOR

FEEDERCOMING COMING FEEDER [FUTURQ|MOTOR

FEEDERFEEDER

LINE LINEREVENUEMETER- REVENUE

METER-ING INGFIELD

APPLI-CATION

TIE FIELDAPPLI-CATION

BUS BUS|(FUTURE) TIE FEEDER 1FEEDER FUTUAUX-

ILIARYPT S PTS

i i(i<i tic- r

£ s. _AUw¥V ¥ ¥¥

E: E: E; E: E ;'A /

E: E:A

ais:ARRANGEMENT 2

nSYN. SYN. IN-IN-(FUTURE: COMINGFEEDERCOMING FEEDER FEEDER FEEDER MOTORMOTOR

FEEDER[FUTURE^LINE LINEFEEDER

REVENUEMETER- IREVENUE

METER-ING INGFIELD

APPLI-CATION

FIELDAPPLI-CATION

BUS TIE 8US (FUTURE)!FEEDER FEEDERTIE(FUTURE) PT'S PT SAUX.

t i l l#k n* ^ ^ * ELa rY ¥ ¥ ¥ ¥ ¥ ¥ YYE E: E E E El

I E: E EA AA vk5. ¥ ¥«1/

Figure 2-4. Two possible arrangements of metalclad switchgear, using OEM switchgear components and POWER/VAC® breakers.

13

System One-Line DiagramREFERENCES

StandardsANSI

StandardIEEE

TitleStandard

IEEE Standard Dictionary of Electrical and Electronic Terms,

Graphic Symbols for Electrical and Electronic Diagrams.Electrical and Electronics Diagrams,

Electrical Power System Device Function.

Application Guide for AC High-Voltage Circuit Breakers Ratedon a Symmetrical Current Basis.

IEEE Guide for Protective Relaying of Utility-ConsumerInterconnections.

100-19771. C42.100-1977

315-19752. Y32.2-1975

3. Y14.15-1966 (R1973)

4. C37.2-1979

5. C37.010-1979

357-19736. C37.95-1974

Electric Power Distribution for Industrial Plants.141-19697.IEEE Recommended Practice for Grounding of Industrial andCommercial Power Systems.IEEE Recommended Practice for Electric Power Systems inCommercial Buildings.

142-19728.

241-19749.

IEEE Recommended Practice for Protection and Coordinationof Industrial and Commercial Power Systems.242-197510.

Codes11. 1981 National Electrical Code — NFPA Publication 70-1981.

Books12. Industrial Power Systems Handbook — D.L, Beeman, Editor McGraw-Hill Book Co., 1955.

Publications13. GEA-11345 — General Electric OEM Metalclad Switchgear Components.Standards may be purchased from:

National Electrical Manufacturers AssociationPublication Department2101 L St. N.W.Washington. D.C. 20037

American National Standards Institute, inc.1430 BroadwayNew York, NY 10018

Institute of Electrical and Electronics Engineers, inc.Service Center445 Hoes LanePiscataway, NJ 08854

National Fire Protection Association470 Atlantic AvenueBoston, MA 02210/

14

Contents

Section 3Circuit Breaker Selection

Page

INTRODUCTION 16

CIRCUIT BREAKER RATINGS 16

SELECTION CONSIDERATIONS .Circuit VoltageSystem FrequencyShort-circuit CurrentClosing and Latching CurrentContinuous Current

1616181818

. 18

SPECIAL SWITCHING APPLICATIONS . . .Repetitive SwitchingAutomatic Reclosing

Calculation of Reclosing CapabilitiesProcedure

Arc Furnace SwitchingReactor SwitchingCapacitor SwitchingFast Bus Transfer

19191919

. . 1922222223

SERVICE CONDITIONSUsual Service Conditions. . .Unusual Service Conditions .

Abnormal Temperature . .High Altitude . ,Other Unusual Conditions

232323232324

. 24BREAKER-MOUNTED ACCESSORIES

/ 24REFERENCES

I,;•.

15

Circuit Breaker Selection<7?,-

INTRODUCTION

Circuit characteristics which must be defined andcompared to the circuit breakers’ capabilities(given in Table 3-1) are:• Circuit voltage• System frequency« Continuous current• Short-circuit current• Closing and latching currentIn addition, certain special application conditionscan influence circuit breaker selection. Specialapplications include the following:• Repetitive switching duty (except arc furnace)• Automatic reclosing• Arc furnace switching• Reactor switching• Capacitor switching• Fast bus transfer• Unusual service conditionsThis section of the Application Guide providesspecific parameters and guidelines for circuitbreaker selection and application. Specifically,those circuit parameters and special applicationsnoted in the preceding paragraph are addressed.

A circuit breaker’s function and intended use areestablished in ANSI-C-37.100-1972, Definitions forPower Switchgear, which defines a circuit breaker as:

“A mechanical switching device, capable ofmaking, carrying, and breaking currentsunder normal circuit conditions and also,making, carrying for a specified time andbreaking currents under specified abnormalcircuit conditions such as those of short-circuit.”

In addition, it is noted that a circuit breaker isintended usually to operate infrequently, althoughsome types are suitable for frequent operation.A circuit breaker is applied generally to carry andswitch load current and to interrupt short-circuitcurrent when required. The application process issimple: each of the duty requirements is specifiedor calculated and is then compared to the cor-responding capability of the circuit breaker. Thefundamental rule for selection of the proper cir-

cuit breaker is that the ratings or relatedcapabilities of the circuit breaker must equal orexceed each of the calculated or specified dutyrequirements of the circuit in which it is applied. (

CIRCUIT BREAKER RATINGS

of ratings, tests, and qualifying terms, refer tothe applicable ANSI and NEMA standards listed inTable 1-1.

POWER/VAC circuit breaker ratings are shown inTable 3- 1 . Interrupting ratings are for 60-Hz appli-cations. For more complete information concerningservice conditions, definitions, and interpretation:

'i

SELECTION CONSIDERATIONS:

CIRCUIT VOLTAGEApplication of the proper circuit breaker requiresa definition of its duty requirements, which canthen be compared with the choice of a circuitbreaker using the ratings and capabilities shownin Table 3-1. It is recommended that ANSI StandardC37.010 (see Ref. 2 of this section) be consultedfor guidance in proper determination of dutyrequirements.Circuit characteristics which must be consideredare discussed in the following paragraphs.

j

VThe nominal voltage classes of medium-voltagemetalclad switchgear are 4.16 kV, 7.2 kV and13.8 kV. Switchgear may be applied at operatingvoltages from 2400 volts through 13,800 volts,provided the maximum circuit operating voltagedoes not exceed the POWER/VAC circuit breakerrated maximum voltage.

iC4L.

'1

‘iA.*Vi

16

Section 3POWER/VAC power circuit breaker characteristics

SYMMETRICAL RATING BASIS ANSI C37.06Identification (6&7>* Rated Values Related Required Capabilities

Voltage Insulation Level Current Current ValuesRated Withstand

Tost VoltageMaximum 3 SecSymmet- Short-

rlcalInter- Current

ruptlna CarringCapability Capability

timeNominal

rmsVoltageClass

Nominal3-phaseClass(MVA)

RatedMaximum

rmsVoltage‘

Low CrestImpulseVoltage

RatedVoltageRangeFactor,

Con-tinuous

Short-circuitRated Rated

MaximumRatedInter-w

(Cycles)

Closingand

LatchingCapability'

rmsCurrent

Frequency Per-mlssableTrippingDelay, Y

(Seconds)

rms rms rms rms (5)Voltage (kV) CurrentRating

at 60 Hz(amperes)

CurrentRating

(at RatedMax KV)

ikA)(4) W

VoltageDivided(kV)(kV) K (kV) K Times Rated

Short-circuitrms Current

(D (2) by K(kV) (kA)

(kA) (kA)

4.76t 4.16t 4.16

250 1.24 19 60 291200 5 2 3.85 36 36 584.76250 1.24 19 2060 2000 5 2 3.85 36 5836

2504.16 4.75 1.24 6019 3000 29 2 3.855 36 36 58350 4.764.16 1.19 19 60 1200 41 4-95 2 49 49 783504.16 4.76 1.19 19 60 2000 41 5 2 4.0 49 49 78

4.16 4.76 1.19350 19 60 413000 5 2 4.0 4949 787.2 500 8.25 951.25 36 1200 33 5 2 6.6 41 41 66

500 0.257.2 1.25 36 2000 3395 6 6.62 41 66415007.2 8.25 1.25 3000 3336 95 5 6.62 4141 66

113.8 500 15 1.30 36 95 1200 18 5 2 11.5 23 23 37f13.8 500 15 36 951.30 2000 18 25 11.5 23 23 37

50013.8 15 1.30 36 95 183000 5 2 11.5 23 23 3713.8 15 1.30750 36 95 281200 5 2 3611.5 36 58V; V 1513.8 750 1.30 36 2095 2000 5 2 11.5 36 583613.8 750 1.30 3615 95 3000 528 2 11.5 5836 3613.8 1000 15 951.30 36 1200 37 11.55 2 48 48 7713.8 151000 1.30 36 95 2000 37 5 2 48 4811.5 7713.8 1000 15 1.30 36 95 3000 5 4837 2 11.5 48 77

Breaker Is type VB1 ‘Numbers In parenthesis refer to the notes, below.

1. Maximum voltage for which thebreaker is designed and the upperlimit for operation.2. K is the ratio of rated maximumvoltage to the lower limit of therange of operating voltage inwhich the required symmetricaland asymmetrical interruptingcapabilities vary in inverse propor-tion to the operating voltage.3. To obtain the required sym-metrical interrupting capability ofa circuit breaker at an operatingvoltage between 1/K times ratedmaximum voltage and rated maxi-mum voltage, the following formulashall be used:

Required Symmetrical InterruptingCapability =Rated short-circuit Current x

5. Current values in this columnare not to be exceeded even foroperating voltages below 1/Ktimes rated maximum voltage. Forvoltages between rated maximumvoltage and 1/K times rated max-imum voltage, follow (3) above.In accordance with ANSI-C37.06,users should confer with themanufacturer on the status ofvarious circuit breaker ratings.6. General Electric POWER/VACcircuit breakers are designated astype VB-“KV”-"MVA’' or typeVB1—“KV”—“ 'MVA".7. NOTE: General Electric reservesthe right to improve the designand/or modify the specifications inthis publication without notice.

(Rated Max. Voltage)(Operating Voltage)

For operating voltages below 1/Ktimes rated maximum voltage, therequired symmetrical interruptingcapability of the circuit breakershall be equal to K times ratedshort-circuit current.4. With the limitation stated in5.10 of ANSI-C37.04 1979, all valuesapply for polyphase and line-to-linefaults. For single phase-to-groundfaults, the specific conditionsstated in 5.10.2,3 of ANSI-C37.04-1979 apply.

f/

i.

V

17

Circuit Breaker SelectionSYSTEM FREQUENCY asymmetrical rms current of 1.6 times the max-

imum symmetrical rms interrupting capability ofthe circuit breaker. Ordinarily this close and latchcapability is satisfactory for most applications.There are some applications, however, in whichthe calculated2 rms value of first-cycle asym-metrical short-circuit current exceeds the closingand latching capability of the circuit breaker.Applications which include a large motor load area typical example. In these cases, breaker selec-tion may depend on closing and latching capabilityrather than symmetrical short-circuit capability.The breaker selected might have the next-highershort-circuit current capability or it might havea higher-than-standard closing and latchingcapability.

The frequency rating of metalclad switchgearshould coincide with the nominal frequency ofthe power system and is available in 60-Hz and50-Hz ratings.

SHORT-CIRCUIT CURRENT

Quick interruption of short-circuit current is usuallyconsidered the primary function of a circuitbreaker. The fault-current interrupting capabilityof POWER/VAC® circuit breakers is stated in three-phase, symmetrical, rms ac amperes. Accordingly,calculation of the maximum available fault duty ofa circuit breaker assumes a three-phase bolted fault.After calculation of short-circuit current duty,

choose a POWER/VAC breaker which has a short-circuit current capability that equals or exceedsthe expected duty, and, remember to consider thecircuit operating voltage when evaluating the cir-oiilfffibaker’s interrupting capability. For example:at 4160 volts, a 4.16 kV — 350 MVA-class circuitbreaker with a rated short-circuit current of 41kA at a maximum rated voltage of 4.76 kV has an

4.76 kV

CONTINUOUS CURRENT

Feeder and main breaker loading determine requiredcontinuous current duty. For continuous loads,select a POWER/VAC breaker with rated con-

tinuous current {defined at 60-Hz) equal to orgreater than load current.Note that circuit breakers have no continuousoverload rating. When considering circuit breakerapplication with a generator, a motor, a trans-former, or other apparatus having a long-timeoverload rating, the circuit breaker (and switch-gear equipment) must have a continuous-currentrating at least equal to the overload rating of theserved apparatus. When applied with a forced-

cooled transformer, the switchgear continuous-current rating must equal or exceed thetransformer forced-cooled current rating.Circuit breakers may be operated, for shortperiods, in excess of rated continuous current.This covers such operations as starting motors orenergizing cold loads.

(interrupting capability of 41 kA x

symmetrical rms current. But at 2.4 kV, theInterrupting capability is 49 kA, the maximumsymmetrical interrupting capability listed in therating tables, because 2.4 kV is less than 4.76kV /"k" = 4.76/1.19 = 4.0 kV. (See footnoteNo. 5, Table 3-1).

= 47 kA4.16 kV

CLOSING AND LATCHING CURRENT

Circuit breakers are designed to stay latched, orto close and latch, against a first-cycle maximum

/

,VV

i. ‘

&

18

Section 3> >

SPECIAL SWITCHING APPLICATIONS under usual service conditions and for other thanarc furnace switching, standard POWER /VAC cir-cuit breakers are capable of operating the numberof times shown in the table. Operating conditions,servicing requirements and permissible effectson the breakers are specified in the notes underthe table.

Application of power circuit breakers for switchingduty may require derating of the circuit breaker.Particular attention should be given to breakersintended for use in any of the following switchingapplications:• Repetitive switching (except arc furnace)• Automatic reclosing® Arc furnace switching• Reactor switching• Capacitor switching• Fast bus transferFor these applications, the usual practice is tofirst select a circuit breaker based on the criteriaprovided under “SELECTION CONSIDERATIONS” ofthis section. Then, consider the switching dutyand, if necessary, redetermine the circuit breakercapabilities (continuous-current rating, interrupt-ing rating, etc.), and factor in any modifiedoperating or maintenance requirements. Recheckthe circuit breakers' evaluated capabilities againstall the basic duty requirements under "SELECTIONCONSIDERATIONS”.if the circuit breaker selected initially, and asderated (or otherwise modified), no longer meetsthe duty requirements of the application, choosethe next-higher rated breaker. Repeat the deratingor rating adjustment process to confirm that thenew breaker has adequate capability.

AUTOMATIC RECLOSINGWhen POWER/VAC circuit breakers are used forautomatic reclosing duty to maintain service corntinuity, they must be derated in accordance withstandard capability factors’. These apply to allhigh-voltage circuit breakers rated up to 72.5 kV,

All POWER/VAC circuit breakers may be used forreclosing duty. Certain system conditions such aslarge motors connected to the bus or electricallyclose generators may prohibit reclosing.Capability factors for POWER/VAC circuit breakersused in automatic reclosing duty applications areshown in Figures 3-1 and 3-2. To ensure properdetermination of POWER/VAC circuit breakercapabilities in reclosing applications, use this step-by-step calculating procedure.T

• l i

Calculation of Reclosing Capabilities

• A duty cycle shall not contain more than fiveopening operations.

• All operations within a 15-minute period areconsidered part of the same duty cycle.

• The circuit breaker may be applied, at thedetermined operating voltage and duty cycle, toa circuit for which the calculated short-circuitcurrent does not exceed the symmetrical inter-rupting capability, as determined by the follow-ing procedure.

• If the X/R ratio for the circuit exceeds 15,refer to ANSI-C37.010 for guidance.

REPETITIVE SWITCHING(EXCEPT ARC FURNACE)

POWER/VAC® circuit breakers can be applied onmost power circuits without attention to frequencyof operation, since highly repetitive switching dutyis uncommon. Typical switching duties includemotor starting, switching of distribution circuits,transformer magnetizing current, and othermiscellaneous load-current switching. Whilemagnitude of current switched in these applica-tions can vary from very light load to the max-imum permissible for a particular circuit breaker,switching is generally infrequent; thus, noderating is required,

Standard POWER/VAC circuit breakers may beoperated as often as 20 times in 10 minutesor 30 times in one hour without derating forswitching duty. Further frequency of operationcapabilities are given in Table 3-2. When operated

Procedure

Step 1 — Determine the breaker symmetrica!interrupting capability at the operat-ing voltage from Table 3-1 (Note 3)./

v.:‘>

19

Circuit Breaker SelectionTable 3-2. Repetitive Duty and Normal Maintenance tor

POWER/VAC® Breakers Used in Mild Environments forOther than Arc Furnace Switching

Number of Operations (Each = 1 Close Plus 1 Open Operation)BreakerMaximum No. of

Operations BeforeServicing

ContinuousTypo Rating —

AmpsInrush-Current SwitchingNo-Load Mochanlcal Continuous Current Switching

Column 4 Column 5Column 3Column 1 Column 2

D, Closing 600% of rated current orless at no less than 30% PF.Otherwise, same as C.

C. Close and trip within rated cur-rent, rated maximum voltage and80% PF or greater.

A. Servicing consists of adjusting,cleaning, lubricating, changingparts, as recommended by theCompany. The operations listedare on the basis of service In amild environment.

B , Close and trip, no-load.

E. Applies.E. Rated control voltage. E. Applies.F. Frequency of operation not more

than 20 In 10 minutes or not morethan 30 In 1 hour.

F. Applies.F. Applies

G. Applies. G. Applies.G. Servicing at Intervals given InColumn 2.

H. AppliesH. No parts replacement. H , Applies.I. Applies I. Applies.I. Breaker meets all current, voltage,

interrupting current ratings.J. At the first servicing Interval, the

amount of vacuum Interruptercontact erosion should be usedto estimate the additional life atthat continued duty.

J. Applies.

K. After 15 full short circuit faultscheck the contact erosion. K. Applies.

10,000 or 10 years 10,000 10,00010,000 minimumAllAll

/

20

Section 3SPECIAL SWITCHING APPLICATIONS under usual service conditions and for other than

arc furnace switching, standard POWER/VAC cir-cuit breakers are capable of operating the numberof times shown in the table. Operating conditions,servicing requirements and permissible effectson the breakers are specified in the notes underthe table.

Application of power circuit breakers for switchingduty may require derating of the circuit breaker.Particular attention should be given to breakersintended for use in any of the following switchingapplications:• Repetitive switching (except arc furnace)• Automatic reclosing• Arc furnace switching• Reactor switching• Capacitor switching• Fast bus transferFor these applications, the usual practice is tofirst select a circuit breaker based on the criteriaprovided under ‘'SELECTION CONSIDERATIONS” ofthis section. Then, consider the switching dutyand, if necessary, redetermine the circuit breakercapabilities (continuous-current rating, interrupt-ing rating, etc.), and factor in any modifiedoperating or maintenance requirements. Recheckthe circuit breakers' evaluated capabilities againstalt the basic duty requirements under "SELECTIONCONSIDERATIONS”.If the circuit breaker selected initially, and asderated (or otherwise modified), no longer meetsthe duty requirements of the application, choosethe next-higher rated breaker. Repeat the deratingor rating adjustment process to confirm that thenew breaker has adequate capability.

AUTOMATIC RECLOSINGWhen POWER/VAC circuit breakers are used forautomatic reclosing duty to maintain service con-tinuity, they must be derated in accordance withstandard capability factors1. These apply to allhigh-voltage circuit breakers rated up to 72.5 kV.All POWER/VAC circuit breakers may be used forreclosing duty. Certain system conditions such aslarge motors connected to the bus or electricallyclose generators may prohibit reclosing.Capability factors for POWER/VAC circuit breakersused in automatic reclosing duty applications areshown in Figures 3-1 and 3-2. To ensure properdetermination of POWER/VAC circuit breakercapabilities in reclosing applications, use this step-by-step calculating procedure,v

Calculation of Reclosing Capabilities

• A duty cycle shall not contain more than fiveopening operations.

• All operations within a 15-minute period areconsidered part of the same duty cycle.

• The circuit breaker may be applied, at thedetermined operating voltage and duty cycle, toa circuit for which the calculated short-circuitcurrent does not exceed the symmetrical inter-rupting capability, as determined by the follow-ing procedure.

• If the X/R ratio for the circuit exceeds 15,refer to ANSI-C37.010 for guidance.

REPETITIVE SWITCHING(EXCEPT ARC FURNACE)

POWER/VAC® circuit breakers can be applied onmost power circuits without attention to frequencyof operation, since highly repetitive switching dutyis uncommon. Typical switching duties includemotor starting, switching of distribution circuits,transformer magnetizing current, and othermiscellaneous load-current switching. Whilemagnitude of current switched in these applica-tions can vary from very light load to the max-imum permissible for a particular circuit breaker,switching is generally infrequent; thus, noderating is required.Standard POWER/VAC circuit breakers may beoperated as often as 20 times in 10 minutesor 30 times in one hour without derating forswitching duty. Further frequency of operationcapabilities are given in Table 3-2. When operated

Procedure

Step 1 — Determine the breaker symmetricalinterrupting capability at the operat-ing voltage from Table 3-1 (Note 3)./

vv;.>

19

Circuit Breaker SelectionTable 3-2. Repetitive Duty and Normal Maintenance for

POWER/VAC® Breakers Used in Mild Environments forOther than Arc Furnace Switching

Number of Operations (Each = 1 Close Plus 1 Open Operation)BreakerContinuous

Type Rating —Amps

Maximum No. ofOperations Before

ServicingInrush-Current SwitchingNo-Load Mechanical Continuous Current Switching

Column 5Column 2 Column 3 Column 4Column 1

D. Closing 600% of rated current orless at no less than 30% PF.Otherwise, same as C.

C. Close and trip within rated cur-rent, rated maximum voltage and80% PF or greater.

A. Servicing consists of adjusting,cleaning, lubricating, changingparts, as recommended by theCompany. The operations listedare on the basis of service In amild environment.

B. Close and trip, no-load.

E. Applies. E. Applies.E. Rated control voltage

F. Applies.F. Frequency of operation not morethan 20 In .10 minutes or not morethan 30 In 1 hour.

F. Applies

G. Servicing at intervals given inColumn 2.

G. Applies.G. Applies.

H. Applies.H. No parts replacement. H. Applies.I. Applies.I. Breaker meets all current, voltage,

interrupting current ratings.I. Applies.

J. At the first servicing Interval, theamount of vacuum interruptercontact erosion should be usedto estimate the additional life atthat continued duty.

J. Applies.

K. After 15 full short circuit faultscheck the contact erosion. K. Applies.

10,00010,000 or 10 years 10,000 minimum 10,000All All

/

r wK:

20

Section 3

*

Breoker Symmetr ica l In ter rupt ing Capabi l i ty InKi loomperes at Operat ing Vol tage

t Step I Va lue )

Figure 3-1. Recloslng capability curve for determining d-j .

o „100 w rT

- Standard Duty Cycle : CO + 15 sec +CO'P oo'c

Gl—OU

2 10 o 90T! o 7u U.ou.0 + 15 sec + CO + 15 sec + CO

* 0 + 0 sec + CO( Same as Fig. I )

'0 + 15 sec + C0 + 15 sec + CO + 15 sec + C00 + 0 sec + C0 + 15 sec + CO

(Zo- 20 S 80

a.o o3 ooa>cc O'a

Io 30 § 700 + l 5 $ ec + C0 + i5 sec + C0 + l 5 sec + C0 + I5 sec +CO

,0 + 0 sec + CO + 15 sec + CO + 15 sec + CO0 + Osec +C0 + 15 sec + CO +60 sec + CO

N*oH <w

DCM I Ia oc 1 ii i i6040

5020 30 40 600 10 70 80Breaker Symmetr ica l In ter rupt ing Capabi l i ty in

Ki loamperes at Operat ing Vol tage( Step I Value )

Figure 3*2. Reclosing capability factor curves for typical duty cycles.

/

21

^ r i f s'. - x.-:*^V.-*H-'.^~fcr:.?t*:&W*:i* s^VY*,"•• - •• '•

* *:V? •., ;•.•;• -•

*;*>' •'; -? y-:•*;if - /i

Circuit Breaker Selection pte,MSyv*o.y.-

Mi

,-v-

•I *Step 2 — Determine the factor d, from the reclos-ing capabiiity curve in Figure 3-1 for thecurrent value determined in Step 1.

Step 3 — Determine the factor D from the follow-ing equation:

REACTOR SWITCHING» •

>;' Y:M!

Consult the factory or nearest sales office forinformation on reactor switching. !rvP

(15-t.)D = d, (n-2) + d, CAPACITOR SWITCHING ;A>'

:>v.:w(15-t2 ) (15-tn) Capacitor banks are generally applied on both

utility and industrial power systems to improvevoltage regulation and system stability. POWER/VAC® circuit breakers are appiicabie to shunt-capacitor-bank switching In accordance with thecapabilities listed in Table 3-3.Shunt-bank capacitor switching means onebreaker feeding one 3-phase capacitor bank. Ifthis circuit is closely paraWeled by another switchedcapacitor bank, see the notes of Table 3-3.

V+ . . . 4* d+ d 11 1515 “i

where:D = total reduction factor (In percent).d, = calculating factor for D in percent

of breaker symmetricai interruptingcapability at operating voitage.

n = totai number of openings in dutycycle.

t, = duration (in seconds) of first timeinterval between operations that isless than 15 seconds.

t2 = duration (in seconds) of second timeinterval between operations that isless than 15 seconds.

tn = duration in nth time interval . . .Step 4 —Calculate the reciosing capability factor

(R) in percent where:R = 100 minus D

For some typical duty cycles. R can bedetermined directly from the appro-priate curves in Figure 3-2.

Step 5 — The revised symmetrical interruptingcapability of the circuit breaker for theoperating voltage and duty cycle desiredis now determined by multiplying theStep 1 symmetrical interrupting capabil -ity by R, as determined in Step 4.

«;

Table 3-3. POWERMACCircuit Breaker Capacitor

Switching Capabilityl

•I:- J

. ,/ Capability (or 1200A, 2000A, and 3000Acontinuous current rated

POmMAQ circuit breakersGeneral Purpose circuit breaker

eBreakerVB-1

CapacitorVoltage

Capacitor SwitchingCapability (Amperes )

Equivalent CapacitorBank Rating (kvar*)

>£v

400 120024004.16-250 400 21004160400012470

138002501.38-500m 250 4400

‘Maximum three-phase, single capacitor bank, nameplate kvar, Including requiredmultiplying factor of 1.35.Footnotes: The capacftonbank rating Is subject to the following conditions:1. The transient voltage from line to ground shall not exceed 3 times maximum

design iine-to-ground crest voltage measured at the breaker terminals.2. The number of restrikes or relgnltlons shall not be limited as long as the transient

voltage to ground does not exceed the value given In Footnote 1.3. The capacitor bank rating applies only to single bank switching as noted herein ,4. Interrupting time is In accordance with the rated Interrupting time of the circuit

breaker .5. For capacitor switching capability of breakers having Definite-Purpose Capacitor

Switching capability (higher than General Purpose rating and or Back-to-SackSwitching) please contact the factory,

s#ST

: T.;:'"'7'

VC ARC FURNACE SWITCHING•^i:.v‘:

Arc furnace switching duty is more repetitivethan normal switching duty. The circuit breakeris applied on the primary side of a reiati ^/ely high-impedance transformer and the usual duty is fre-quent switching (50 to 100 times per day) of thetransformer magnetizing current. Switching isrequired when the transformer is de-energized fortap changing, when taking meit samples, or whenadding alloys, in addition to this switching duty,transformer through-faults must occasionally beinterrupted.

>' v- ji

*»: * * A --;..- J;/Y \Vv?

Ti:ft.:-

Section 3FAST BUS TRANSFER Typical dead times for fast transfer, using stan-

dard and special POWER/VAC breakers, are shownin Table 3-4.Fast bus transfer is normally used for transfer-

ring a generating station auxiliary bus to anemergency power source upon failure of the nor-mal source of power. ^During this transfer it isessential that bus "dead time” be as short aspossible to prevent loss of critical auxiliary func-tions. “Fast" transfer means there is no inten-tional time delay in the transfer of a bus or loadfrom one source of power to another. POWER/VAC®

circuit breakers with stored-energy closing meetthe critical requirements for fast transfer.The preferred circuit breaker operation sequenceused to achieve fast transfer consists of givinga trip signal to the opening breaker. Then a “b"contact (open when the breaker contacts areclosed) on the opening breaker initiates closing ofthe second breaker. The amount of dead timedepends upon whether the POWER/VAC breaker isstandard or is provided with a special early "b”(faster) contact and special closing coil.

Table 3-4.Typical Dead-TimesUsing POWER/VAC

Circuit BreakersDead Bus Times

(milliseconds)Trip then close usingstandard “b” contact

Power/VacBreakers

ControlVoltage

No Arching (1) With Arching (2)

All - See 4-2 88VBI Ratings 100

Footnotes:(1) Main contact parting to main contact making.(2) End of arcing to main contact making*NOTE: For “fast transfer" breakers refer to factory.

SERVICE CONDITIONST:'( it /

POWER /VAC breaker and OEM component ratingsand capabilities are based on operation under cer-tain defined service conditions, defined as “usual".Conditions other than usual are called “unusual".Factors used to classify service conditions arealtitude, ambient temperature, and a varietyof others, such as the presence of atmosphericcontaminants, unusual storage conditions, andrequirements for tamper-resistance. These factorsare specified for circuit breakers in ANSI-C37.04-1979 (Circuit Breaker Rating Structure)and for equipment in ANS1-C37.20.2-1983 (Switch-gear Assemblies), and are summarized here forapplication guidance.Application of POWER/VAC circuit breakers underconditions other than "usual” may requirederating, special construction or use of specialprotective features.

• Where ambient temperature is not above 40 Cor below -30 C (104 F and - 22 F)

• Where the altitude is not above 3300 feet(1000 meters).NOTE: For switchgear assemblies (breakers

and housings combined) there is oneadditional stipulation:

• Where the effect of solar radiation is notsignificant. (See Ref. 5 of this section.)

UNUSUAL SERVICE CONDITIONSAbnormal TemperatureThe planned use of POWER/VAC circuit breakersor switchgear components at other than normalambient temperatures (+ 40 C to - 30 C) shall beconsidered as special. Such applications should bereferred to the nearest General Electric SalesOffice for evaluation.

USUAL SERVICE CONDITIONSHigh AltitudePOWER/VAC circuit breakers and switchgear com-ponents utilize air for an insulating and cooling

/POWER/VAC circuit breakers (and switchgearcomponents) are suitable for operation at theirstandard nameplate ratings:

23

Circuit Breaker SelectionFor proper application, the derated values shouldequal or exceed the duty requirements of theapplication. Short circuit current ratings and ratedoperating voltage are not affected.

medium. Operation at altitudes above 1000meters will result in a higher temperature riseand lower dielectric strength because the air isthinner. Thus, certain circuit breaker and switch-gear capabilities must be corrected to adjust forhigh-altitude operation.For operation of POWER/VAC ® circuit breakers andswitchgear components at altitudes above 1000meters, the basic impulse insulation level (BIL)and the rated continuous current shall each bemultiplied by the appropriate correction factorsshown in Table 3-5.

Other Unusual Conditions

Besides abnormal temperature and high altitudethere are other unusual service conditions whichmay require special protecting features or affectconstruction. Some of these are:• Exposure to corrosive vapors, explosive fumes,

excessive dust or dirt, salt spray, steam, drip-ping water, and other similar conditions.

• Exposure to abnormal vibration, shock, unusualtransportation, or special storage conditions.

• installations accessible to the general public.

Table 3-5.AltitudeCorrectionFactorsforPOWER/VACCircuitBreakersand SwitchgearComponents

Rating Correction Factor *Altitude

(feet) RatedContinuous

CurrentInsulation Level

1.001.003,300 (and below)5,000

10,0000.950.990.800.96

Footnote:'Values for Intermediate altitudes may be determined by linear interpolation.

BREAKER MOUNTED ACCESSORIES

A four-stage auxiliary switch is furnished on everyPOWER/VAC circuit breaker. Three contacts areused for the close-and-trip circuits, leaving two"a” and three "b" contacts for Purchaser use.Additional switch stages are not available on thebreaker. They must be provided using an auxiliaryswitch stationary-mounted on the equipment.

Each breaker and its equipment skeleton will beequipped with Rating Interference blocks so thatonly the proper rated breaker can be inserted intothe equipment breaker cubicle.

REFERENCES/

4. ANSI Standard C37.20.2-1983, SwitchgearAssemblies.

5. ANSI Standard C37.24-1971, Guide for Evalu-ating the Effect of Solar Radiation on OutdoorMetalclad Switchgear.

6. ANSI Standard C37.07-1969 (R-1976), inter-rupting Capacity Factors for Reclosing Servicefor AC High Voltage Circuit Breakers.

1. ANSI Standard C37.06-1979, Schedulesof Preferred Ratings and Related RequiredCapabilities for AC High Voltage Circuit Break-ers Rated on a Symmetrica] Current Basis.

2. ANSI Standard C37.010-1979, Application Guidefor AC High Voltage Circuit Breakers.

3. ANSI Standard C37.04-1979, Circuit BreakerRating Structure.

24

Contentsr,

Section 4Control Power Equipment

Page

INTRODUCTION 26

CONTROL POWER REQUIREMENTSClosing and Tripping

Breaker TrippingBreaker Closing

Breaker Remote Racking

2626272828

Vv• >

25

Control Power EquipmentINTRODUCTION

guidance in selecting the proper type of controlpower equipment.This section of the Application Guide addresses

specific control power requirements and provides

CLOSING AND TRIPPINGCONTROL POWER REQUIREMENTS

Successful operation of metalclad switchgeardepends on a reliable source of control powerwhich will, at all times, maintain a voltage at theterminals of electrically operated devices withinthe rated operating voltage range. In general, theoperating voltage range of a switchgear equip-ment is determined by the rated operating voltagerange of the circuit breaker. These ranges, asestablished by NEMA standards, are given inTable 4-1.Operating currents for POWER/VAC® circuitbreakers are given in Table 4-2.

Equipment necessary to provide control power formetalclad switchgear must have sufficient capacityto deliver the maximum power required, at theproper voltage, under any operating condition.The most important consideration in selecting acontrol power source is that it must provide trippingpower for the circuit breakers during protectiverelay operation. Also, it should be capable of closingthe breakers without direct manual operation.Other requirements can include:

DC ACIndicating lampsEquipment heatersEquipment lights and

convenience outlets

Indicating lampsEmergency lightsEmergency motorsExcitation power

(brushless motors, etc.) Excitation power(brushless motors, etc.)

Table 4-1.Standard Control Voltageand Operating Ranges for

POWER/VACCircuitBreakersEquipment ventilatingfans

NominalControlVoltage

Remote lights (onstructures, etc,)

All of these requirements must be considered indetermining the type and rating of the controlpower source.Sources of control power for metalclad switchgearare storage batteries (with charger) for dc control,and transformers for ac control. When ac is usedfor closing, the tripping power must be obtainedfrom capacitors fed from rectified ac, or from a“tripping only’' battery. The choice between thesealternatives depends on factors such as the sizeof the switchgear installation, the need to operatebreakers simultaneously, the degree of reliabilityrequired, expansion plans, the expected environ-mental conditions, maintenance support availability,and the economics related to these considerations.

Operating Range(Volts)

Stored-energy MechanismVolts Spring Motor and

Closing SpringRelease Coil

Tripping Coll

28-5670-140

140-280

48 38-56100-140200-280

DC 125250

not available inPOWER/VAC

120 104-127208-254AC 240

(60 Hz)

/

26

Section 4( (

Table 41Operating Currents of POWER/VAC® Circuit Breakers

Tripping Current*(Amperes)Closing Curent

(Amperes)At 125

Volts DCAt 250

Volts DCAt 48

Volts DCAt 210

Volts ACAt 48

Volts DCAt 125

Volts DCAt 260

Volts DCAt 120

Volts ACType ofBreaker Closing

SpringRelease

ClosingSpring

Release

ClosingSpring

Release

ClosingSpring

Release

ClosingSpring

ReleaseSpringMotor

SpringMotor SpringMotor

SpringMotor SpringMotor

Coil Coil Coll Coll Coil

VB-4.16-250

VB-4.16*350

VB-7.2-5008.0 12.3 3.7 2.2 2.3 8 0 5 19.0 10.0 4.546

VB-13.8-500

VB-13.8-750

VB-13.8-1000

VB1-4.16-25017.06.9 12.0 3.4 4.5 1.6 2.5 12.0 4.5 10.0 2.5 7.3 4.7

VB1-13.8-500

*Fuses for the tripping circuit should have an ampere rating of at least 2 times the tripping current and not less than 35 amperes..

Breaker TrippingPOWER/VAC circuit breakers are provided withmeans for manual tripping (push button) and forelectrically actuated tripping (trip coil). Electricallyactuated tripping devices are used for two functions:

• As a means of opening the breaker in the processof normal switching operations initiated by anoperator, or

® As a means of automatically opening thebreaker for circuit protective purposes, underabnormal conditions.

Electrical tripping is accomplished when externalpower, from a battery or from a rectified acsource (with capacitor), is directed into thebreaker trip coil. Normal switching tripping usesan operator control switch. Automatic trippingoccurs when a contact on a protective relaycloses, actuated by power circuit instrumenttransformers,

When deciding between dc battery trip and accapacitor trip, the following points must beconsidered:

• For a single breaker, or a few breakers, thecapacitor trip device has lower cost than abattery, but a trip device is required foreach breaker.

• A battery source is more reliable, but requiresmore maintenance than a capacitor trip device.

• If a battery is used for tripping, dc closingpower can also be obtained for little additionalcost.

DC BATTERY TRIP — When properly maintained,a battery offers the most reliable tripping source.It requires no auxiliary tripping devices, and usessingle-contact relays which directly energize asingle trip coil in the breaker. Power circuitvoltage and current conditions during time offaults do not affect a battery-trip supply; there-fore, it is considered the best source for circuitbreaker tripping. Additional advantages are that,usually, only one battery is required for each loca-tion, and it may be used to operate other equip-ment such as high-voltage circuit breakers orprotective grounding switches.Once a battery has been selected for tripping pur-poses, it can, after proper evaluation of additionalloads, also be used for breaker closing power. Forindoor applications, if the battery can be locatedclose to the switchgear, a 48-volt battery operatinglevel is usually suitable. For more general use, a125-volt battery is recommended, but 250-voltbatteries can be used if other conditions requirethat voltage. In outdoor locations, space considera-tions in the switchgear usually restrict the batteryto a 48-volt rating,

Long service can be obtained from batteries whenthey receive proper maintenance, are kept fullycharged, and when the electrolyte is maintainedat the proper level. For equipment in outlyinglocations where periodic battery maintenancewould be difficult, the capacitor trip device mayoffer overall advantages.

6

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(ki

27

Control Power Equipmentsource

CAPACITOR TRIPControlpowertransformer

ACAn “auto-charge” capacitor trip device is available,and consists of the ‘'simple” device, plus a voltageamplifier, a battery, and a battery charger. Undernormal conditions, with 230-volt ac power usedfor breaker closing, the single-cell, sealed, recharge-able, nickel-cadmium battery is maintained at fullcharge by the small charger connected to the230-volt ac source, Upon loss of ac power, thevoltage amplifier steps up the low battery voltageto the higher voltage needed to maintain chargeon the capacitor for several days.The “auto-charge” capacitor trip device (ST-230-3)is available whenever ac trip or capacitor tripis specified.

Battery" charger

-cHhrControl powerbatteryrt AC closing

power

(A) OC stored - energy close (?) Ac stored - energy close

ManuallychargedAC lighting or

general purposesourceBreaker Closing

Closing power availability should be independentof voltage conditions on the power systemassociated with the switchgear. Accordingly,a 125-volt or 250-volt dc battery is normally con-sidered to be the most reliable auxiliary powersource. Nevertheless, in many instances, thestorage battery or other independent powersource necessary to achieve this goal may requirean investment which is considered too high forthe advantages gained. This is particularly truefor small lineups, consisting of only a few circuitbreaker units.Generally, the choice between dc closing powerderived from a battery and ac closing powerderived from a control power transformer is aneconomic one, dictated by desired system reliability.There are other factors, however, which alsoinfluence this choice. These are:

• Need to close breakers with the power systemde-energized.

• Availability of housing space for a battery andits associated charging equipment.

• Estimated lowest ambient temperature and itseffect on battery capability.

• Maintenance requirements for a battery andbattery charger .

• Expected future equipment additions whichmay affect the present choice of closing-powersource.

(?) Ac stored - energy close @Monually stored- energy close

Figure 4-1. Closing mechanism arrangements.

The POWER/VAC® stored-energy operatingmechanism can use the closing arrangementsshown in Figures 4-1A through 4-1D.When the mechanism is operated from alternatingcurrent, the current required is such that it canbe taken from a control power transformer or ageneral-purpose or lighting source, as shown byFigures 4-1B and 4-1C. The energy for the nextoperation is stored in the springs as soon as thebreaker is closed. To permit control switch orautomatic initiation of closing, the ac source mustalso be present at the time of breaker closing toenergize the spring-release solenoid. The POWER/VAC breaker mechanism is also suitable formanual operation (Figure 4-1D), both for chargingthe springs and for releasing them to close thebreaker, in an emergency situation.

BREAKER REMOTE RACKING

When the usual manual racking means is supple-

mented by a motor, the load on the control powersource is the same as for the breaker spring-charging motor: see Table 4-2./

i

28

Contentsm

Section 5System and Equipment Protection

Page

SURGE PROTECTION 30

I'. '.--;i

/

29

System andEquipment Protection Cl?

Surge suppressors in lieu of surge arresters maybe ordered from the MVSBS. The 200A IRDISCHARGE PROTECTIVE LEVEL is:

4.16 kV = 9.25 - 10.9 kV7.2 kV = 17.2 - 23.0 kV13.8 kV = 32.1 - 38.0 kV

These devices are rated to operate continuously atrated line-to-line voltage for up to 1000 hours.For other low BIL equipment (i.e., ventilated dry-type transformers) consult the manufacturer forrecommendation for surge protection.

SURGE PROTECTION

Every medium voltage ac power system is subjectto transient voltages in excess of the normaloperating voltages. There are many sources oftransient voltages.The most prominent ones are:

• Lightning.• Physical contact with a higher voltage system,

• Resonant effects in series inductive-capacitivecircuits.

• Repetitive restrike (intermittent grounds).« Switching surges.To mitigate the effects of these transient voltages,both surge arresters and, where appropriate,surge capacitors should be used. Surge arresterslimit the crest voltage of a voltage surge; surgecapacitors reduce the steepness of the voltagewave which reaches the protected equipment.Surge capacitors, to be most effective, should belocated as close to the protected equipment(usually motors) as possible with minimum induc-tance connections.For ac rotating-machine protection refer toGeneral Electric Handbook Section 591D.

VACUUM BREAKER HEAT LOSS

Heat loss data is estimated to be as follows forvacuum breakers:

1 — 1200A Breaker = 550 Watts1 - 2000A Breaker = 1200 Watts1 — 3000A Breaker = 2000 WattsAdequate ventilation must be provided to main-

tain ANSI temperature rise values within themetalclad equipment.

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