400kv protection_ gk

400KV PROTECTION400KV PROTECTIONPREPARED BYPREPARED BY

GOPALA KRISHNA PALEPUGOPALA KRISHNA PALEPUADE/MRT(PROTECTION)ADE/MRT(PROTECTION)

BASICS BASICS OF OF

ONE AND HALF ONE AND HALF CIRCUIT BREAKER CIRCUIT BREAKER

SCHEMESCHEMEPREPARED BY

GOPALA KRISHNA PALEPUADE/MRT(PROTECTION)

ONE & HALF BREAKER DESCRIPTIONONE & HALF BREAKER DESCRIPTIONBUS-1 1. IN THIS TWO BUSES ARE PRIOVIDED.

BUS-2

2. THESE TWO BUSES ARE INTER CONNECTED BY THREE BREAKERS.3. THEY ARE DESIGNATED AS 1-52 CB, 2-52 CB, 3-52 CB.

1-52 CB

2-52 CB

3-52 CB

4. LINE-1 IS CONNECTED IN BETWEEN 1-52 CB & 2-52 CB.

LINE-1

5. LINE-2 IS CONNECTED IN BETWEEN 3-52 CB & 2-52 CB.

LINE-2

6. LINE-1 HAVING TWO FEEDING PATHS i.eA. VIA BUS-1 & 1-52 CBB. VIA BUS-2, 3-52 CB & 2-52 CB

7. LINE-2 HAVING TWO FEEDING PATHS i.eA. VIA BUS-2 & 3-52 CBB. VIA BUS-1, 1-52 CB & 2-52 CB

8. FOR INTURUPTING LINE-1 THE 1-52CB AND 2-52CB IS TO BE TRIPPED.9. FOR INTURUPTING LINE-2 THE 3-52CB & 2-52CB IS TO BE TRIPPED.

10. FOR ANY PROBLEM IN LINE-1 OR LINE-2 THE MIDDLE BREAKER(2-52 CB) MUST TRIP.

13. SO THESE TWO FEEDERS CONTROLLING BY THREE CIRCUIT BREAKERS IT IS CALLED ONE & HALF BREAKER SYSTEM.

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15. THE BAY BETWEEN LINE-1 & LINE-2 IS CALLED TIE BAY FOR FEEDER-1 & 2. 16. THE BAY BETWEEN BUS-2 & LINE-2 IS CALLED MAIN BAY FOR FEEDER-2.

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GOPALA KRISHNA PALEPU M.Tech(EMID), (MBA)

ADE/MRT/400KV SS/APTRANSCOMAMIDIPALLY, HYDERABAD

11. NORMALLY IN ALL TYPES OF BUSBAR CONFIGUARATIONS ONE BREAKER IS SUFFICIENT FOR ONE FEEDER.

14. THE BAY BETWEEN BUS-1 & LINE-1 IS CALLED MAIN BAY FOR FEEDER-1.

12. HERE TWO FEEDERS ARE CONTROLLING BY THREE BREAKERS.

ONE & HALF BREAKER SYSTEMONE & HALF BREAKER SYSTEM(4CTS METHOD)(4CTS METHOD)

LINE 1

1-89

1-89A

11--52CB52CB

1-CT3

3

3

3-89

3-89A

33--52CB52CB

3-CT3

22--52CB52CB

2-ACT 2-BCT

2-89A 2-89B

1-89L 3-89T

BUS-1 BUS-2

T/F-1

P1

P1 P1

P1

P2 P2

P2 P2


LINE 1

1-89A

11--52CB52CB

1-CT3

3

3

3-89

3-89A

33--52CB52CB

3-CT3

22--52CB52CB

1-LCT

2-CT

2-89A 2-89B

1-89L 3-89T

BUS-1 BUS-2

T/F-1

3 3-TCT

1-89

P2

P1

P2

P2

P2

P1 P1

P2

P1 P1


LINE 1

1-89A

11--52CB52CB

1B-CT33

3

3-89

3-89A

33--52CB52CB

3B-CT3

22--52CB52CB

2B-CT

2-89A 2-89B

1-89L 3-89T

BUS-1 BUS-2

T/F-1

3

1-89

P2

P1P2

P2

P2

P1 P1

P2P1

P13

P2

P11A-CT

2A-CT

3A-CT


LINE 1

1-89A

11--52CB52CB

1B-CT33

3

3-89

3-89A

33--52CB52CB

3B-CT3

22--52CB52CB

2B-CT

2-89A 2-89B

1-89L 3-89T

BUS-1 BUS-2

T/F-1

3

1-89

P2

P1P2

P2

P2

P1 P1

P2P1

P13P2

P11L-CT

2A-CT

3T-CT

PROTECTION TRIP SCHEMEPROTECTION TRIP SCHEME

BUS-1 BUS-2

1-52CB 3-52CB2-52CB

8686--AAMTR/MTR/HSTRHSTR

ABBABBREL521REL521MAINMAIN--11

8686--BBMTR/MTR/HSTRHSTR







ABBABBRET521RET521MAINMAIN--11


TRIP COIL-1 TRIP COIL-1 TRIP COIL-1


8686--A : GROUPA : GROUP--A MASTER TRIP RELAY / HIGH SPEED TRIP RELAY A MASTER TRIP RELAY / HIGH SPEED TRIP RELAY 8686--B : GROUPB : GROUP--B MASTER TRIP RELAY / HIGH SPEED TRIP RELAYB MASTER TRIP RELAY / HIGH SPEED TRIP RELAY

SINGLE BUS SYSTEMSINGLE BUS SYSTEM

11--52CB52CB1-89 1-89L

3

1-CT

P2 P13 33 3

CORES1 2 3 4 5

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1-CVT

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331 2 333

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CURRENT TRANSFORMERCURRENT TRANSFORMERCONNECTIONS IN 4CT METHODCONNECTIONS IN 4CT METHOD

11-- CTCT 22--BCTBCT 22--ACTACT 33--CTCTCORECORE--1 1

(PS)(PS)

CT SECONDARY CT SECONDARY CORE IS CORE IS

CONNECTED TO CONNECTED TO BUSBARBUSBAR--1 1

PROTECTIONPROTECTION

SPARESPARE SPARESPARE CT SECONDARY CT SECONDARY CORE IS CORE IS

CONNECTED TO CONNECTED TO BUSBARBUSBAR--2 2

PROTECTION PROTECTION

CORECORE--2 2 (PS)(PS)

BUSBARBUSBAR--1 1 CHECKUP CHECKUP

PROTECTION PROTECTION (SPARE)(SPARE)

SPARESPARE SPARESPARE BUSBARBUSBAR--2 2 CHECKUP CHECKUP


CORECORE--3 3 (0.5/0.2)(0.5/0.2)

2CTs SECONDARIES ARE 2CTs SECONDARIES ARE CONNECTED IN PARALLEL AND CONNECTED IN PARALLEL AND

CONNECTED TO CONNECTED TO PANEL METERS & ENERGY METERPANEL METERS & ENERGY METER


CONNECTED TO CONNECTED TO PANEL METERS & ENERGY METERPANEL METERS & ENERGY METER



CONNECTED TO CONNECTED TO MAINMAIN--2 PROTECTION2 PROTECTION

AFTER LBB/BFRAFTER LBB/BFR


CONNECTED TO CONNECTED TO BACKUP PROTECTIONBACKUP PROTECTION

AFTER LBB/BFRAFTER LBB/BFR


2CTs SECONDARIES ARE 2CTs SECONDARIES ARE CONNECTED CONNECTED

IN PARALLEL AND CONNECTED TO IN PARALLEL AND CONNECTED TO MAINMAIN--1 PROTECTION1 PROTECTION

2CTs SECONDARIES ARE 2CTs SECONDARIES ARE CONNECTED CONNECTED

IN PARALLEL AND CONNECTED TO IN PARALLEL AND CONNECTED TO MAIN PROTECTIONMAIN PROTECTION

LINE PROTECTIONLINE PROTECTION(CT CONNECTIONS(CT CONNECTIONS IN IN 4CTs METHOD)4CTs METHOD)

LINE 1

1-89

1-89A

11--52CB52CB

3-89

3-89A

33--52CB52CB

22--52CB52CB2-89A

2-89B1-89L3-89T

BUS-1 BUS-2

T/F-1

1-CT

P1

P2

33

33

3

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23

45

3

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CORES1 2 3 4 5

2B-CT

P1 P2

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METERINGMETERING

MAINMAIN--2 PROTECTION2 PROTECTION


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1-CVT

..

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LINE 1

1-89

1-89A

11--52CB52CB

3-89

3-89A

33--52CB52CB

22--52CB52CB2-89A

2-89B1-89L3-89T

BUS-1 BUS-2

T/F-1

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CORES1 2 3 4 5

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P1

P2

2A-CT

3-CT

P1P2

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METERINGMETERING



TRANSFORMER PROTECTIONTRANSFORMER PROTECTION(CT CONNECTIONS(CT CONNECTIONS IN IN 4CTs METHOD)4CTs METHOD)

LV CT

333

3

32

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CURRENT TRANSFORMER CURRENT TRANSFORMER CONNECTIONS IN 5CT METHODCONNECTIONS IN 5CT METHOD

11--CTCT 11--LCTLCT 22--CTCT 33--TCTTCT 33--CTCT


BUSBARBUSBAR--11PROTECTIONPROTECTION

TEED PROTTEED PROT--11(BAY 1&2)(BAY 1&2)












CORECORE--3 3 (0.5/0.2)(0.5/0.2)

SPARESPARE METERING &METERING &ENERGY ENERGY METERMETER


SPARESPARE


TEED PROTTEED PROT--22(BAY 1&2) (BAY 1&2)

AFTERAFTERLBB/BFRLBB/BFR

(1(1--52) 52)

MAINMAIN--22PROTECTIONPROTECTION


AFTERAFTERLBB/BFRLBB/BFR

(2(2--52) 52)

BACKUPBACKUPPROTECTIONPROTECTION


AFTERAFTERLBB/BFR LBB/BFR

(3(3--52)52)





MAINMAINPROTECTIONPROTECTION


LINE PROTECTIONLINE PROTECTION(CT CONNECTIONS(CT CONNECTIONS IN IN 5CTs METHOD)5CTs METHOD)

LINE 1

1-89

1-89A

11--52CB52CB

3-89

3-89A

33--52CB52CB

22--52CB52CB2-89A

2-89B1-89L3-89T

BUS-1 BUS-2

T/F-1

1-CT

P1

P2

33

33

3

CO

RE

S1

23

4

5

333 33CORES

12345

2-CTP1 P2

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METERINGMETERINGMAINMAIN--2 PROTECTION2 PROTECTION


333

3

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2

3

1-CVT

33

33

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1L-CT

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T/F PROTECTIONT/F PROTECTION(CT CONNECTIONS(CT CONNECTIONS IN IN 5CTs METHOD)5CTs METHOD)

LINE 1

1-89

1-89A

11--52CB52CB

3-89

3-89A

33--52CB52CB

22--52CB52CB2-89A

2-89B1-89L3-89T

BUS-1 BUS-2

T/F-1

3-CT

P1

P2

333 33CORES

12345

2-CTP1 P2

METERINGMETERINGMAINMAIN--2 PROTECTION2 PROTECTIONMAINMAIN--1 PROTECTION1 PROTECTION

333

3

1

2

3

1-CVT

33

33

3

CO

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S1

23

45

3T-CT

P1

P2

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LV CT


(GIS or AIS with DEAD TANK CBs) (GIS or AIS with DEAD TANK CBs)

1B1B--CTCT 1A1A--CTCT 2B2B--CTCT 2A2A--CTCT 3A3A--CTCT 3B3B--CTCT


BUSBARBUSBAR--1 1 PROTECTIONPROTECTION

2CTs SECONDARIES 2CTs SECONDARIES ARE CONNECTED ARE CONNECTED IN PARALLEL AND IN PARALLEL AND CONNECTED TO CONNECTED TO


2CTs SECONDARIES 2CTs SECONDARIES ARE CONNECTED ARE CONNECTED IN PARALLEL AND IN PARALLEL AND CONNECTED TO CONNECTED TO


BUSBARBUSBAR--2 2 PROTECTIONPROTECTION


BUSBARBUSBAR--1 1 CHECKUP CHECKUP PROTECTION PROTECTION

(SPARE)(SPARE)

2CTs SECONDARIES 2CTs SECONDARIES ARE CONNECTED INARE CONNECTED IN

PARALLEL AND PARALLEL AND CONNECTED TOCONNECTED TO

MAINMAIN--2 PROTECTION 2 PROTECTION AFTER LBB/BFRAFTER LBB/BFR


PARALLEL AND PARALLEL AND CONNECTED TO CONNECTED TO

BACKUP PROTECTION BACKUP PROTECTION AFTER LBB/BFRAFTER LBB/BFR


(SPARE)(SPARE)

CORECORE--3 3 (0.5/0.2)(0.5/0.2)

SPARESPARE 2CTs SECONDARIES 2CTs SECONDARIES ARE CONNECTED INARE CONNECTED IN


PANEL METERS & PANEL METERS & ENERGY METERENERGY METER



PANEL METERS & PANEL METERS & ENERGY METERENERGY METER

SPARESPARE


11--CTCT 1L1L--CTCT 2A2A--CTCT 2B2B--CTCT 3T3T--CTCT 33--CTCTCORECORE--1 1 (PS)(PS)



SPARESPARE SPARESPARE

SPARESPARE

SPARESPARE


AFTER LBB/BFRAFTER LBB/BFR(2(2--52)52)





(SPARE)(SPARE)


SPARESPARE



METERING &METERING &ENERGY ENERGY METERMETER

BACKUPBACKUPPROTECTIONPROTECTION

BUSBARBUSBAR--2 2 CHECKUPCHECKUPPROTECTION PROTECTION

(SPARE)(SPARE)

CORECORE--3 3 (0.5/0.2)(0.5/0.2)


SPARESPARE SPARESPARE

MAINMAINPROTECTIONPROTECTION



AFTER LBB/BFR AFTER LBB/BFR (1(1--52) 52)




AFTER LBB/BFR AFTER LBB/BFR (3(3--52)52)






COMPARISION BETWEEN COMPARISION BETWEEN 4CT METHOD & 5CT METHOD4CT METHOD & 5CT METHOD

CT PURPOSECT PURPOSE 5 CT METHOD5 CT METHOD 4 CT METHOD4 CT METHODBUSBAR &

BUSBAR CHECKUP PROTECTION

1 CT FOR BUS1 CT FOR BUS--1 & 1 & 3 CT FOR BUS3 CT FOR BUS--22

1 CT FOR BUS1 CT FOR BUS--1 & 1 & 3 CT FOR BUS3 CT FOR BUS--22

MAIN-1, MAIN-2 PROTECTION &

METERING

1L CT FOR FEEDER1L CT FOR FEEDER--1 & 1 & 3L CT FOR FEEDER3L CT FOR FEEDER--22

1 CT & 2B CT SECONDARIES ARE CONNECTED 1 CT & 2B CT SECONDARIES ARE CONNECTED PARALLEL FOR FEEDERPARALLEL FOR FEEDER--1 & 1 &

3 CT & 2A CT SECONDARIES ARE CONNECTED 3 CT & 2A CT SECONDARIES ARE CONNECTED PARALLEL FOR FEEDERPARALLEL FOR FEEDER--22

ADDITIONAL PROTECTION

TEEDTEED--1 PROTECTION (HIGH Z)1 PROTECTION (HIGH Z)(1 CT, 1L CT & 2 CT FOR FEEDER(1 CT, 1L CT & 2 CT FOR FEEDER--1 & 1 & 3 CT, 3L CT & 2 CT FOR FEEDER3 CT, 3L CT & 2 CT FOR FEEDER--2)2)

TEEDTEED--2 PROTECTION (LOW Z)2 PROTECTION (LOW Z)(1 CT, 1L CT & 2 CT FOR FEEDER(1 CT, 1L CT & 2 CT FOR FEEDER--1 &1 &3 CT, 3L CT & 2 CT FOR FEEDER3 CT, 3L CT & 2 CT FOR FEEDER--2)2)

STUBSTUB--1 PROTECTION1 PROTECTION( MAIN( MAIN--1 DISTANCE SCHEME IS CONVERTED 1 DISTANCE SCHEME IS CONVERTED TO STUBTO STUB--1 WHEN LINE ISOLATOR OPENS) 1 WHEN LINE ISOLATOR OPENS)

STUBSTUB--2 PROTECTION2 PROTECTION( MAIN( MAIN--2 DISTANCE SCHEME IS CONVERTED 2 DISTANCE SCHEME IS CONVERTED TO STUBTO STUB--2 WHEN LINE ISOLATOR OPENS)2 WHEN LINE ISOLATOR OPENS)

OTHER INFORMATION

TEED PROTECTIONTEED PROTECTION( THE 3NOs CTs ARE CONEECTED IN TEE SHAPE ( THE 3NOs CTs ARE CONEECTED IN TEE SHAPE AND CONNECTED TO DIFFERENTIAL RELAY SO AND CONNECTED TO DIFFERENTIAL RELAY SO IT IS CALLED TEED PROTECTION). IT IS CALLED TEED PROTECTION). TEEDTEED--11 IS CONNECTED ON SUMMATION OF 3 TEE IS CONNECTED ON SUMMATION OF 3 TEE SHAPED CTs & CONNECTED TO 3SHAPED CTs & CONNECTED TO 3--PH HIGH PH HIGH IMPEDENCE DIFFERENTIAL RELAY . IMPEDENCE DIFFERENTIAL RELAY . TEEDTEED--22 IS CONNECTED TO 3 WINDING LOW IS CONNECTED TO 3 WINDING LOW IMPEDENCE BIASED DIFFERENTIAL RELAY OF IMPEDENCE BIASED DIFFERENTIAL RELAY OF 3 TEE SHAPED CTs. 3 TEE SHAPED CTs. ( TEED PROTECTION WILL BE USED TO COVER ( TEED PROTECTION WILL BE USED TO COVER BLIND AREA BETWEEN TEE SHAPED CTs BLIND AREA BETWEEN TEE SHAPED CTs CONNECTED IN DIFF PROTECTION)CONNECTED IN DIFF PROTECTION)

STUB PROTECTIONSTUB PROTECTION( THERE IS NO UNCOVERED BLIND ZONE ) (WHEN ( THERE IS NO UNCOVERED BLIND ZONE ) (WHEN

EVER LINE ISOLATOR OPENS MAINEVER LINE ISOLATOR OPENS MAIN--1 & MAIN1 & MAIN--2 2 WILL BE CONVERTED TO STUB/ BUS OVER LOAD WILL BE CONVERTED TO STUB/ BUS OVER LOAD

RELAYS. STUB MEANS DEAD END) RELAYS. STUB MEANS DEAD END) ( STUB IS INBUILT FEATURE IN ADVANCED ( STUB IS INBUILT FEATURE IN ADVANCED NUMERICAL DISTANCE SCHEME RELAYS)NUMERICAL DISTANCE SCHEME RELAYS)

INFORMATION REGARDING INFORMATION REGARDING 6CT METHOD 6CT METHOD

THE LOCATION OF THE CTs ON BOTH SIDES OF THE CIRCUIT BREAKERS IS TYPICAL FOR SUBSTATIONS WITH DEAD-TANK CIRCUIT BREAKERS or GIS CIRCUIT BREAKERS.

LIVE-TANK CIRCUIT BREAKERS MAY HAVE CTs ONLY ON ONE SIDE TO REDUCE COST.

A FAULT BETWEEN CIRCUIT BREAKERS AND CT(END FAULT) MAY THEN STILL BE FED FROM ONE SIDE EVEN WHEN THE BREAKER HAS BEEN OPENED.

CONSEQUENTLY, FINAL FAULT CLEARING BY CASCADED TRIPPING HAS TO BE ACCEPTED IN THIS CASE.

STUB PROTECTION RELAY PROVIDED IN CASE OF LINE ISOLATOR OPENS.

1B-CT FOR BUSBAR-1 AND 3B-CT FOR BUSBAR-2 FOR BUSBAR PROTECTION & BUSBAR CHECKUP PROTECTION.

1A-CT & 2B-CT SECONDARIES ARE PARALLED AND CONNECTED TO MAIN-1 PROTECTION, MAIN-2 PROTECTION AFTER LBB/BFR AND METERING.

ONE & HALF BREAKER ( 6 CT METHOD) WITH PROTECTION SCHEMEONE & HALF BREAKER ( 6 CT METHOD) WITH PROTECTION SCHEME

TYPICAL ONE & HALF BREAKER TYPICAL ONE & HALF BREAKER SYSTEM ADOPTED IN GISSYSTEM ADOPTED IN GIS

DS : DISCONNECTOR SWITCH, GS: GROUNDING SWITCH, CT: CURRENT TRANSFORMER, VD: VOLTAGE DIVIDER

400KV C.T. INFORMATION400KV C.T. INFORMATION

33U

3U

3

U3

1S11S21S3

2S12S22S3

3S13S23S33S4

5S15S25S35S44S14S24S34S4

P1 P2

P1 P2

31S11S21S3

32S12S22S3

3

U

3S13S23S33S4

3U 5S15S25S

35S

4

3U 4S14S24S34S4

EYE BOLT EYE BOLT DESIGNDESIGN

HAIRHAIRPIN / PIN /

U SHAPE U SHAPE DESIGNDESIGN

DEAD TANK DESIGNDEAD TANK DESIGN

PRIMARY CONNECTIONS : P1 PRIMARY CONNECTIONS : P1 P2P2CURRENT RATING : 2000 AMPSCURRENT RATING : 2000 AMPS

SECONDARY CONNECTIONSSECONDARY CONNECTIONSCURRENT RATING : 1ACURRENT RATING : 1ACORESCORES CLASSCLASS PURPOSEPURPOSE

2000/ 1A2000/ 1A 1000/ 1A1000/ 1A 500/ 1A500/ 1A

CORECORE--11 PSPS BUSBAR BUSBAR PROTECTIONPROTECTION 1S1 1S1 1S31S31S2 1S2 1S3 1S3 1S1 1S1 1S21S2

____

CORECORE--22 PSPSBUSBAR BUSBAR CHECKUP CHECKUP

PROTECTIONPROTECTION2S1 2S1 2S32S3 2S2 2S2 2S3 2S3 2S1 2S1 2S22S2 ____

CORECORE--33 0.5 / 0.20.5 / 0.2 METERINGMETERING 3S1 3S1 3S43S4 3S2 3S2 3S43S43S1 3S1 3S23S23S3 3S3 3S43S43S2 3S2 3S33S3

CORECORE--44 PSPS MAINMAIN--2 2 PROTECTIONPROTECTION 4S1 4S1 4S44S44S2 4S2 4S44S44S1 4S1 4S24S2

4S3 4S3 4S44S44S2 4S2 4S34S3

CORECORE--55 PSPS MAINMAIN--1 1 PROTECTIONPROTECTION 5S1 5S1 5S45S45S2 5S2 5S45S45S1 5S1 5S25S2

5S3 5S3 5S45S45S2 5S2 5S35S3

CT LOAD FLOW DIAGRAMS WHEN CT LOAD FLOW DIAGRAMS WHEN 11--52 CB OPEN52 CB OPEN

1-52CB 3-52CB3

2-52CBP1P2

0A

S2 S40A

2000-1000-500/1A

3

P2P11000A

S4 S21.0A

2000-1000-500/1A

3

P1P21000A

S3 S42.0A

2000-1000-500/1A

3

P2P11500A

S4 S33.0A

2000-1000-500/1A1-CT 2-ACT 2-BCT 3-CT

LINE AT/F1000A 500A

MAINMAIN--1/ 1/ MAINMAIN--2/ 2/ METERMETER

FORFORLINELINE


FORFORAT/FAT/F

0A

0A

1.0A1.0A

3.0A

3.0A

2.0A

2.0A 2.0A

1.0A 1.0A

1.0A

1.0A

CT LOAD FLOW DIAGRAMS WHENCT LOAD FLOW DIAGRAMS WHEN22--52 CB OPEN52 CB OPEN

1-52CB 3-52CB3

2-52CBP1P2

1000A

S2 S41.0A

2000-1000-500/1A

3

P2P10A

S4 S20A

2000-1000-500/1A

3

P1P20A

S3 S40A

2000-1000-500/1A

3

P2P1500A

S4 S31.0A

2000-1000-500/1A1-CT 2-ACT 2-BCT 3-CT

LINE AT/F1000A 500A


FORFORLINELINE


FORFORAT/FAT/F

1.0A

1.0A

1.0A1.0A

1.0A

1.0A

0A

0A 0A

0A 0A

0A

0A

CT LOAD FLOW DIAGRAMS WHEN CT LOAD FLOW DIAGRAMS WHEN 33--52 CB OPEN52 CB OPEN

1-52CB 3-52CB3

2-52CBP1P2

1500A

S2 S41.5A

2000-1000-500/1A

3

P2P1500A

S4 S20.5A

2000-1000-500/1A

3

P1P2500A

S3 S41.0A

2000-1000-500/1A

3

P2P10A

S4 S30A

2000-1000-500/1A1-CT 2-ACT 2-BCT 3-CT

LINE AT/F1000A 500A


FORFORLINELINE


FORFORAT/FAT/F

1.5A

1.5A

1.0A1.0A

0A

0A

1.0A

1.0A 1.0A

0.5A 0.5A

0.5A

0.5A

MAINMAIN--1, MAIN1, MAIN--22PROTECTION &PROTECTION &

METERINGMETERINGFOR LINE FOR LINE

ADOPTED IN ADOPTED IN ONE AND HALFONE AND HALF

CIRCUIT BREAKER CIRCUIT BREAKER SCHEMESCHEME PREPARED BYGOPALA KRISHNA PALEPU

ADE/MRT(PROTECTION)

NORMS OF PROTECTION FOLLOWED IN APTRANSCO NORMS OF PROTECTION FOLLOWED IN APTRANSCO FOR TRANSMISIION LINES & DISTRIBUTION LINES ( FEEDER / LINE PROTFOR TRANSMISIION LINES & DISTRIBUTION LINES ( FEEDER / LINE PROTECTION )ECTION )

Sr.NoSr.No VOLTAGE VOLTAGE MAINMAIN-- 1 PROTECTION1 PROTECTION MAINMAIN--2 PROTECTION/ BACKUP PROTECTION2 PROTECTION/ BACKUP PROTECTION1.1. 11 KV LINES11 KV LINES 2 O/L + E/F ( 51 + 51N )2 O/L + E/F ( 51 + 51N ) --2.2. 33 KV LINES33 KV LINES 3 O/L + E/F ( 51 + 51N )3 O/L + E/F ( 51 + 51N ) --3.3. 66 KV LINES66 KV LINES4.4. 132 KV LINES132 KV LINES

SWITCHED DISTANCE SCHEME SWITCHED DISTANCE SCHEME ORORNUMERICAL DISTANCE SCHEME (21P+ 21N)NUMERICAL DISTANCE SCHEME (21P+ 21N)

3 O/L + E/F 3 O/L + E/F ( 50 + 50N + 51 + 51N + 67 + 67N )( 50 + 50N + 51 + 51N + 67 + 67N )

5.5. 220 KV LINES220 KV LINES NON SWITCHED DISTANCE SCHEME NON SWITCHED DISTANCE SCHEME ORORNUMERICAL DISTANCE SCHEME (21P + 21N)NUMERICAL DISTANCE SCHEME (21P + 21N)SWITCHED DISTANCE SCHEME SWITCHED DISTANCE SCHEME OROR

NUMERICAL DISTANCE SCHEME (21P+ 21N)NUMERICAL DISTANCE SCHEME (21P+ 21N)

6.6. 400 KV LINES400 KV LINES NON SWITCHED DISTANCE SCHEME NON SWITCHED DISTANCE SCHEME ORORNUMERICAL DISTANCE SCHEME (21P + 21N)NUMERICAL DISTANCE SCHEME (21P + 21N)NON SWITCHED DISTANCE SCHEME NON SWITCHED DISTANCE SCHEME OROR

NUMERICAL DISTANCE SCHEME (21P + 21N)NUMERICAL DISTANCE SCHEME (21P + 21N)IF MAINIF MAIN--1 & MAIN1 & MAIN--2 ARE NUMERICAL RELAYS BOTH SHOULD BE SEPARATE 2 ARE NUMERICAL RELAYS BOTH SHOULD BE SEPARATE CHARECTERESTICS, MODELS AND ALGORITHAMS (SHOULD NOT BE DUPLICATECHARECTERESTICS, MODELS AND ALGORITHAMS (SHOULD NOT BE DUPLICATED) AND D) AND ALL FEATURES SHOULD BE AVAILABLE IN BOTH SCHEMES AND BOTH RELAYSALL FEATURES SHOULD BE AVAILABLE IN BOTH SCHEMES AND BOTH RELAYS SHOULD SHOULD BE 100% REDENDENCY IN ALL ASPECTS.BE 100% REDENDENCY IN ALL ASPECTS.ZONEZONE--1: 80% OF MAIN LINE1: 80% OF MAIN LINEZONEZONE--2: 100% OF MAIN LINE + 50% OF SHORTEST LINE AT OTHER END2: 100% OF MAIN LINE + 50% OF SHORTEST LINE AT OTHER ENDZONEZONE--3: 100% OF MAIN LINE + 100% OF SHORTEST LINE AT OTHER END3: 100% OF MAIN LINE + 100% OF SHORTEST LINE AT OTHER ENDZONEZONE--4: 100% OF MAIN LINE + (100% OF SHORTEST LINE + 20% OF LONGEST L4: 100% OF MAIN LINE + (100% OF SHORTEST LINE + 20% OF LONGEST LINE)INE)

AT OTHER END.AT OTHER END.

MAINMAIN--1 PROTECTION FOR LINE1 PROTECTION FOR LINE(4CT METHOD)(4CT METHOD)

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REL 521REL 5213 3 3

3 3 3

IR5 / A511IY5 / A531IB5 / A551

IN5 / A571

1-CT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

2-BCT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

5S4 5S4 5S4

5S25S2 5S2

P2P2P2 CT MB

CT MB

P2P2P2

5S4 5S4 5S4

5S25S2 5S2

VR11 / E111VY11 / E131VB11 / E151VN11 / E171

1-CVT

CORE 1

200VA

CLASS: 3P

MAINMAIN--1 PROTECTION FOR LINE1 PROTECTION FOR LINE(4CT METHOD) (NEW DEVELOPMENT)(4CT METHOD) (NEW DEVELOPMENT)

3 3 3

3 3 3IR5 / A511IY5 / A531IB5 / A551

IN5 / A571

1-CT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

2-BCT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

5S4 5S4 5S4

5S25S2 5S2

P2P2P2 CT MB

CT MB

P2P2P2

5S4 5S4 5S4

5S25S2 5S2

VR11 / E111VY11 / E131VB11 / E151VN11 / E171

1-CVT

CORE 1

200VA

CLASS: 3P

IA =250.10 AIB =250.10 A IC =250.10 AVAB =400.0 KVVBC =400.0 KVVCA =400.0 KV

ESC ENT

ENABLEDTRIP TARGET RESET

INSTTIMECOMMSOTFZONE1ZONE2ZONE3ZONE4

PH-APH-BPH-CGND505179 RESET79 LOCKOUT

SEL- 421PROTECTIONAUTOMATIONCONTROL

SELIR5 / A511IY5 / A531IB5 / A551

IN5 / A571


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ACTIVE START TRIP

REL 521REL 5213 3 3

IR5 / A511IY5 / A531IB5 / A551

IN5 / A571

1-LCT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

5S4 5S4 5S4

5S25S2 5S2

P2P2P2 CT MBVR11 / E111VY11 / E131VB11 / E151VN11 / E171

1-CVT

CORE 1

200VA

CLASS: 3P


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ACTIVE START TRIP

REL 316REL 3163 3 3

3 3 3IR4 / C411IY4 / C431IB4 / C451

IN4 / C471

1-CT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

2-BCT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

4S4 4S4 4S4

4S24S2 4S2

P2P2P2 CT MB

CT MB

P2P2P2

4S4 4S4 4S4

4S24S2 4S2

VR21 / E211VY21 / E231VB21 / E251VN21 / E271

1-CVT

CORE 2

200VA

CLASS: 3P

LBB / BFR

RAICA

LBB / BFR

RAICA

50ZT

50Z

MAINMAIN--2 PROTECTION FOR LINE2 PROTECTION FOR LINE(4CT METHOD) ( NEW DEVELOPMENT)(4CT METHOD) ( NEW DEVELOPMENT)

3 3 3

3 3 3IR4 / C411IY4 / C431IB4 / C451

IN4 / C471

1-CT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

2-BCT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

4S4 4S4 4S4

4S24S2 4S2

P2P2P2 CT MB

CT MB

P2P2P2

4S4 4S4 4S4

4S24S2 4S2

VR21 / E211VY21 / E231VB21 / E251VN21 / E271

1-CVT

CORE 2

200VA

CLASS: 3P

IR4 / C411IY4 / C431IB4 / C451

IN4 / C471

MULTI FUNCTION NUMERICAL RELAY FOR MULTI FUNCTION NUMERICAL RELAY FOR MULTI BREAKER, MULTI CT & CVT/PT APPLICATION MULTI BREAKER, MULTI CT & CVT/PT APPLICATION

(NEW APPLICATION) (ONE & HALF BREAKER SYSTEM or RING BUS SYSTEM)(NEW APPLICATION) (ONE & HALF BREAKER SYSTEM or RING BUS SYSTEM)

1-52 CB 2-52 CB 3-52 CB3 3

LINE

1-52,2-52: MAIN & TIE CIRCUIT BREAKER21P: PHASE DISTANCE PROTECTION21G: GROUND DISTANCE PROTECTION27: UNDER VOLTAGE RELAY67: DIRECTIONAL RELAY50: INST OVER CURRENT RELAY51: TIME OVER CURRENT RELAY59: OVER VOLTAGE RELAY64: EARTH FAULT RELAY50BF-1: LBB/BFR OF MAIN CB50BF-2: LBB/BFR OF TIE CB79-1,2: AUTO RECLOSURE RELAY OF

MAIN & TIE CB25-1,2: CHECK SYNCHRONISAM RELAYFOR MAIN & TIE CB

67 50 BF-1 50 BF-2

21G 79-1 79-2

21P 25-1 25-2

50 51 27 59

3

3

3

33

3

BUS-1 PT BUS-2 PT

LINE CVT


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ACTIVE START TRIP

REL 316REL 3163 3 3

IR4 / C411IY4 / C431IB4 / C451

IN4 / C471

1-LCT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

4S4 4S4 4S4

4S24S2 4S2

P2P2P2 CT MBVR21 / E211VY21 / E231VB21 / E251VN21 / E271

1-CVT

CORE 2

200VA

CLASS: 3P

MULTI FUNCTION PANEL METERING & ENERGY METERMULTI FUNCTION PANEL METERING & ENERGY METER(4CT METHOD)(4CT METHOD)

3 3 3

3 3 3IR3 / D311IY3 / D331IB3 / D351

IN3 / D371

1-CT

CORE-3CTR: 2000-1000-500/1A

CLASS: 0.5

2-BCT

CORE-3CTR: 2000-1000-500/1A

CLASS: 0.5

3S4 3S4 3S4

3S23S2 3S2

P2P2P2 CT MB

CT MB

3S4 3S4 3S4

3S23S2 3S2

VR31 / E311VY31 / E331VB31 / E351

VN31 / E371

1-CVT

CORE 3

100VA

CLASS: 0.5P2P2P2

LD/G MVAR

+ MWATTS

KVOLTS

AMPS

PANEL METER

3 3 3

IR3 / D311IY3 / D331IB3 / D351

IN3 / D371

1-LCT

CORE-3CTR: 2000-1000-500/1A

CLASS: 0.5/0.2

3S4 3S4 3S4

3S23S2 3S2

P2P2P2 CT MB

VR31 / E311VY31 / E331VB31 / E351

VN31 / E371

1-CVT

CORE 3

100VA

CLASS: 0.5/0.2

LD/G MVAR

+ MWATTS

KVOLTS

AMPS

PANEL METER

MULTI FUNCTION PANEL METERING & ENERGY METERMULTI FUNCTION PANEL METERING & ENERGY METER(5CT METHOD)(5CT METHOD)

BUSBARBUSBARPROTECTIONPROTECTION

SCHEMES SCHEMES ADOPTED INADOPTED IN

ONE AND HALFONE AND HALFCIRCUIT BREAKER CIRCUIT BREAKER



BASICS OF BUSBAR PROTECTIONBASICS OF BUSBAR PROTECTIONNEED FOR BUSBAR PROTECTIONNEED FOR BUSBAR PROTECTION

IN ITS ABSENCE FAULT CLEARING TAKES PLACE IN ZONE-2 OF DISTANCE RELAY BY REMOTE END TRIPPING.

THIS MEANS SLOW AND UNSELECTIVE TRIPPING AND WIDE SPREAD BLACKOUT.EFFECT OF DELAYED CLEARENCEEFFECT OF DELAYED CLEARENCE

GREATER DAMAGE AT FAULT POINT.INDIRECT SHOCK TO CONNECTED EQUIPMENT LIKE SHAFTS OF

GENERATOR AND WINDINGS OF TRANSFORMER.BASIC THEORYBASIC THEORY

KIRCHOFFs CURRENT LAW STATES THAT THE SUM OF THE CURRENTS ENTERING A GIVEN NODE MUST BE EQUAL TO THE CURRENTS LEAVING AT THAT NODE.BUS BAR PROTECTION SYSTEMSBUS BAR PROTECTION SYSTEMSLOW IMPEDENCE DIFFERENTIAL PROTECTION

THE MOST SUITABLE PROTECTION SCHEME FOR DOUBLE AND MULTIPLE BUSBAR SYSTEMS (WITH OR WITHOUT TRANSFER BUS) WITH FEEDERS BEINGSWITCHED BETWEEN SECTIONS OF BUSBAR, WHICH OPERATES WITH FULL SELECTIVITY FOR ALL POSSIBLE BUSBAR CONFIGUARATIONS.HIGH IMPEDENCE DIFFERENCIAL PROTECTION

THE HIGH IMPEDENCE PROTECTION SCHEME, ON THE OTHER HAND, IS A GOOD SOLUTION FOR SINGLE BUSBAR ARRANGEMENTS , ONE & HALF BREAKER SYSTEMS OR RING BUSBARS, PROVIDING THAT APPROPRIATE DEDICATED CTCORES ARE AVAILABLE FOR THIS USE ALONE.

HIGH IMPEDENCE DIFFERENCIAL PROTECTIONSENSTIVE, STABLE & FAST PROTECTION FOR SINGLE BUSBAR

ARRANGEMENTS AND ONE & HALF BREAKER SYSTEMS. THE SYSTEM HAS LIMITS WHEN USED IN COMPLEX BUSBAR CONFIGUARATIONS.

HOWEVER, SPECIAL CT REQUIREMENTS, ADDITIONAL HIGH VOLTAGE DEVICE PROTECTION, DEMANDING MAINTANENCE ETC PUT RESTRICTIONS IN ITS APPLICATIONS.LIMITATIONS OF CONVENTIONAL HIGH IMPEDENCE DIFFERENTIAL RELAYPUTS STRINGENT REQUIREMENTS ON CTs.NEED FOR DEDICATED CT CORES.IDENTICAL CT RATIO, MAGNETISING IMPEDENCE.AUX CTs RATIO CORRECTIONS UNACCEPTABLE.IN ABILITY TO COPE WITH INCREASING FAULT CURRENT.SLOW RESPONSE.BASIC OPERATING TIME EXCLUDING RELAY TIME IS 15 20ms.

THIS RELAY REQUIRES CHECK ZONE FEATURE. THE TRIP COMMAND IS ONLY GIVEN WHEN BOTH A DISCRIMINATING & CHECK ZONE SYSTEM OPERATES.LOW IMPEDENCE DIFFERENTIAL PROTECTION

LOW IMPEDENCE PROTECTION(PERCENTAGE BIASED BUS DIFFERENTIAL RELAY) IS PREFARABLE FOR THE PROTECTION OF DOUBLE AND MULTIPLE BUSBAR SYSTEMS.ADVANTAGES

FREE OF ANY NEED FOR MATCHED CT CHARACTERESTICS OR RATIOs, LOW LEAKAGE REACTANCE OR RESISTANCE.

OTHER PROTECTIVE RELAYS CAN BE INCLUDED IN THE SAME CIRCUIT.STABLE FOR INFINITE FAULT LEVELS. INSENSITIVE TO CT SATURATION.DETECTS FAULTS WITHIN 1 2ms & INITIATES TRIPPING WITHIN 5 7ms.

BASICS OF BUS BAR PROTECTIONBASICS OF BUS BAR PROTECTIONBASIC THEORY

EXTERNAL FAULT

KIRCHOFFs CURENT LAW STATES THAT THE SUM OF THE CURRENTS ENTERING A GIVEN NODE MUST BE EQUAL TO THE CURRENTS LEAVING THAT NODE

I6

I4

I2

I5

I3

I1

IF

IF= I6= I1+I2+I3+I4+I5

INTERNAL FAULT

I6

I4

I2

I5

I3

I1IF

IF= I1+I2+I3+I4+I5+I6

DIFFERENCE BETWEEN BUSBAR SCHEMESDIFFERENCE BETWEEN BUSBAR SCHEMESDETAILSDETAILS HIGH IMPEDENCE BUSBAR HIGH IMPEDENCE BUSBAR

PROTECTIONPROTECTIONPERCENTAGE BIASED LOW PERCENTAGE BIASED LOW

IMPEDENCE BUS BAR IMPEDENCE BUS BAR PROTECTIONPROTECTION

PRINCIPLE THE CURRENTS ENTERING AND LEAVING THE BUSBAR ARE COMPARED CONTINUOSLY. IT INVOLVES CHOOSING OF IMPEDENCE HIGH ENOUGH STABLISE THE RELAY FOR HEAVY EXTERNAL FAULTS

IT HAS DIFFERENTIAL AND BIAS SETTING. THE RESULTANT BIAS IS PROPOTIONAL TO ARITHMATIC SUM OF ALL CURRENTS, WHEREAS THE OPERATING CURRENT IS VECTOR SUM OF ALL CIRCUIT CURRENTS.

CTs IT REQUIRES ALL IDENTICAL CT RATIOs & TURNS RATIO. LOW RESISTANCE OF SECONDARY WINDINGMINIMUM KNEE POINT VOLTAGE OF 300-500V.LOW MAGNETISING CURRENT(FEW MILLIAMPS).

IT CAN WORK WITH CTs OF UNEQUAL RATIOS ALSO. FREE OF ANY NEED OF MATCHED CT CHARACTERESTIC OR RATIOs LOW LEAKAGE REACTANCE OR RESISTANCE. OTHER PROTECTIVE RELAYS CAN BE INCLUDED IN THE SAME CIRCUIT.

BURDEN IMPOSES COMPARATIVELY HIGH BURDEN ON CTs. AUXILIARY CTs REDUCE THE PERFORMANCE OF THE SCHEME

IMPOSES LESS BURDEN ON CTs. AUXILIARY CTs HAVE NO EFFECT ON PERFORMANCE OF SCHEME.

CT SATURATION OPERATION OF SCHEME EVEN WHEN CTs GET SATURATED DURING INTERNAL FAULTS.OPERATION OF SCHEME EVEN WHEN CTs GET SATURATED DURING INTERNAL FAULTS. INSENSITIVE TO CT SATURATION.

UTILISATION IT IS GOOD SOLUTION FOR SINGLE BUSBAR ARRANGEMENTS, ONE & HALF BREAKER SYSTEMS OR RING BUSBAR SYSTEMS.

MOST SUITABLE FOR DOUBLE AND MULTIPLE BUSBAR SYSTEMS ( WITH OR WITHOUT TRANSFER BUS).

OPERATING TIME

BASIC OPERATING TIME EXCLUDING RELAY TIME IS 15 20 Ms.

DETECTS FAULTS WITH IN 1 2 Ms AND INITIATES TRIPPING WITH IN 5-7mS.

STABILITY INABILITY TO COPE WITH INCREASING FAULT CURRENTSTABLE FOR INFINITE FAULT LEVEL.

PERFORMANCE HIGHLY SENSITIVE FOR INTERNAL FAULTS AND COMPLETELY STABLE FOR EXTERNAL FAULTS.HIGHLY SENSITIVE FOR INTERNAL FAULTS AND COMPLETELY STABLE FOR EXTERNAL FAULTS.

ADDITIONAL PROTECTION

THIS RELAY REQUIRES CHECK ZONE FEATURE. THE TRIP COMMAND IS ONLY GIVEN WHEN BOTH A DISCRIMINATING & CHECK ZONE SYSTEM OPERATES.

THIS RELAY HAS IN BUILT CHECK ZONE FEATURE (NO SEPARATE CHECKZONE FEATURE) i.e OVER CURRENT STARTING RELAY PROVIDED.

BUS BAR PROTECTIONBUS BAR PROTECTION(4CT & 5CT METHOD)(4CT & 5CT METHOD)

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REB 521REB 521

3 3 3

3 3 3

IR1 / B111IY1 / B131IB1 / B151

IN1 / B1711-CT

CORE-1CTR: 2000-1000/1A

CLASS: PS

3-CT

CORE-1CTR: 2000-1000/1A

CLASS: PS

1S3 1S3 1S3

1S11S1 1S1

P2P2P2 CT MB

CT MB

P2P2P2

1S3 1S3 1S3

1S11S1 1S1

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ACTIVE START TRIP

REB 316REB 316

BUS BAR PROTECTION

FOR BUS-1

BUS BAR PROTECTION

FOR BUS-2

IR1 / B111IY1 / B131IB1 / B151

IN1 / B171

BUS BAR PROTECTIONBUS BAR PROTECTIONABB RADSS BUS BARABB RADSS BUS BAR--2 PROTECTION2 PROTECTION

ABB RADSS BUS BARABB RADSS BUS BAR--1 PROTECTION1 PROTECTIONBUS-1

BUS-2

3

31CT1-52CB

2-52CB

3-52CB

3CT 3

34CT4-52CB

5-52CB

6-52CB

6CT 3

37CT7-52CB

8-52CB

9-52CB

9CT 3

310CT10-52CB

11-52CB

12-52CB

12CT 3

313CT13-52CB

14-52CB

15-52CB

15CT 3

316CT16-52CB

17-52CB

18-52CB

18CT

BUSBARBUSBAR--1 PROTECTION TRIPPING SCHEME1 PROTECTION TRIPPING SCHEME

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REB 521REB 521

HIGH SPEEDHIGH SPEEDTRIP RELAYTRIP RELAY

FOR FOR 11--52 CB52 CB

TO CLOSE CKT INTERLOCKTO BLOCK A/RTO TRIP COIL-1TO TRIP COIL-2DIRECT TRIP SEND CH-1DIRECT TRIP SEND CH-2TO DISTURBENCE RECORDER

11--52 CB PANEL52 CB PANEL






1010--52CB PANEL52CB PANEL















11--52 CB PANEL52 CB PANELTRIP FROM 50 LBB

TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB

+VE BUSBAR PANEL

BUSBARBUSBAR--2 PROTECTION TRIPPING SCHEME2 PROTECTION TRIPPING SCHEME

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ACTIVE START TRIP

REB 316REB 316










1212--52CB PANEL52CB PANEL
















TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB


TO START 50 LBB

+VE BUSBAR PANEL

MISCELENEOUSMISCELENEOUSRELAYS & PROTECTIONSRELAYS & PROTECTIONS

ADOPTED FOR LINE INADOPTED FOR LINE INONE AND HALF ONE AND HALF

CIRCUIT BREAKERCIRCUIT BREAKERSCHEME SCHEME

(STUB, TEED, LBB/BFR AND AUTO (STUB, TEED, LBB/BFR AND AUTO RECLOSURE FUNCTIONS)RECLOSURE FUNCTIONS)

PREPARED BYGOPALA KRISHNA PALEPU

ADE/MRT(PROTECTION)

STUBSTUB--1/ STUB1/ STUB--2 PROTECTION2 PROTECTION1-52CB 2-52CB 3-52CBBUS-1 BUS-23 3

33

LINE-1 AT/F-1

STUB-1&2(BAY 1&2)

WHEN A LINE IS SUPPLIED VIA TWO CIRCUIT BREAKERS IN A ONE & HALFWHEN A LINE IS SUPPLIED VIA TWO CIRCUIT BREAKERS IN A ONE & HALF CIRCUIT CIRCUIT BREAKER ARRANGEMENT, THE LINE PROTECTION INCLUDES THE AREA BETWEBREAKER ARRANGEMENT, THE LINE PROTECTION INCLUDES THE AREA BETWEEN THE TWO EN THE TWO CTs. HOWEVER, WHEN THE LINE ISOLATOR IS OPEN THE LINE CVTs FCTs. HOWEVER, WHEN THE LINE ISOLATOR IS OPEN THE LINE CVTs FOR THE DISTANCE OR THE DISTANCE PROTECTION ARE CONNECTED TO THE LINE AND CANNOT PROVIDE THE CORPROTECTION ARE CONNECTED TO THE LINE AND CANNOT PROVIDE THE CORRECT RECT VOLTAGE FOR THE STUB END.(i.e THE AREA BETWEEN THE LINE ISOLATOVOLTAGE FOR THE STUB END.(i.e THE AREA BETWEEN THE LINE ISOLATOR AND CTs) R AND CTs) (STUB = DEAD END)(STUB = DEAD END)

TO PROVIDE PROTECTION FOR A FAULT IN THIS AREA, REL 521/ REL 316TO PROVIDE PROTECTION FOR A FAULT IN THIS AREA, REL 521/ REL 316 IS IS PROVIDED WITH A STUB PROTECTION WHICH GIVES AN BUS OVER CURRENT PROVIDED WITH A STUB PROTECTION WHICH GIVES AN BUS OVER CURRENT TRIP IF THE TRIP IF THE LINE ISOLATOR IS OPEN AND THE CURRENT EXCEEDS THE SET VALUE IN LINE ISOLATOR IS OPEN AND THE CURRENT EXCEEDS THE SET VALUE IN ANY PHASE.ANY PHASE.

STUBSTUB--1 (BAY 1&2) 1 (BAY 1&2) OPERATESOPERATES

IT OPERATES THE 3PH TRIP GRIT OPERATES THE 3PH TRIP GR--A MAIN CB (1A MAIN CB (1--52CB) 52CB) AND 3PH TRIP GRAND 3PH TRIP GR--A TIE CB (2A TIE CB (2--52CB)52CB)

STUBSTUB--2 (BAY 1&2) 2 (BAY 1&2) OPERATESOPERATES

IT OPERATES THE 3PH TRIP GRIT OPERATES THE 3PH TRIP GR--B MAIN CB (1B MAIN CB (1--52CB) 52CB) AND 3PH TRIP GRAND 3PH TRIP GR--B TIE CB (2B TIE CB (2--52CB)52CB)

1-89L

REL 521REL 521

REL 316REL 316

DISTANCE RELAYS CONVERTED TODISTANCE RELAYS CONVERTED TOSTUB/BUS OVER LOAD RELAYSSTUB/BUS OVER LOAD RELAYSWHEN LINE ISOLATOR OPENSWHEN LINE ISOLATOR OPENS

STUB PROTECTION TRIP SCHEMESTUB PROTECTION TRIP SCHEME

BUS-1 BUS-2

1-52CB 2-52CB






ABBABBREL521REL521STUBSTUB--11

ABBABBREL316REL316STUBSTUB--22

TRIP COIL-1 TRIP COIL-1

TRIP COIL-2 TRIP COIL-2


LINE ISOLATOR OPENS THIS INTERLINE ISOLATOR OPENS THIS INTERLOCK WILL INITIATE MAINLOCK WILL INITIATE MAIN--1 REL 521 1 REL 521 & CONVERTED STUB& CONVERTED STUB--1 PROTECTION1 PROTECTION

LINE ISOLATOR OPENS THIS INTERLINE ISOLATOR OPENS THIS INTERLOCK WILL INITIATE MAINLOCK WILL INITIATE MAIN--2 REL 316 2 REL 316 & CONVERTED STUB& CONVERTED STUB--2 PROTECTION2 PROTECTION

TEEDTEED--1 PROTECTION1 PROTECTION{BAY1&2}(5CT METHOD){BAY1&2}(5CT METHOD)

C

E

DISPLAY

ACTIVE START TRIP

RADHARADHA

3 3 3

3 3 31-CT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

1-LCT

CORE-1CTR: 2000-1000/1A

CLASS: PS

P2P2P2

P1P1P1

3 3 32-CT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

P1P1P1P2P2P2

P1P1P1

P2P2P2

5S4 5S4 5S4

5S25S2 5S2

5S4 5S4 5S4

5S25S2 5S2

1S4 1S4 1S4

1S11S1 1S1TEED-1 PROTECTION FOR BAY 2&3 IS ALSO SAME AS ABOVE AND THE FOLLOWING CTs & CORES ARE USED3-CT(CORE-5), 2-CT(CORE-1) & 3-TCT(CORE-1) ARE STARRED AND CONNECTED TO TEED-1 PROTECTION

IR5IY5IB5

IN5

IR5IY5IB5

IN5

IR1IY1IB1

IN1

TEEDTEED--2 PROTECTION2 PROTECTION{BAY1&2}(5CT METHOD){BAY1&2}(5CT METHOD)

3 3 3

3 3 3

1-CT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

1-LCT

CORE-2CTR: 2000-1000/1A

CLASS: PS

4S4 4S4 4S4

4S24S2 4S2

P2P2P2 CT MB

CT MBP2P2P2

2S2 2S2 2S2

2S32S3 2S3

3 3 3

2-CT

CORE-4CTR: 2000-1000-500/1A

CLASS: PS

4S2 4S2 4S2

4S44S4 4S4

P2P2P2CT MB

C

E

DISPLAY

ACTIVE START TRIP

RADSBRADSB

R

A

I

C

A

L

B

B

/

B

F

R

R

A

I

C

A

L

B

B

/

B

F

R

TEED-2 PROTECTION FOR BAY 2&3 IS ALSO SAME AS ABOVE AND THE FOLLOWING CTs & CORES ARE USED

3-CT(CORE-4), 2-CT(CORE-2) &

3-TCT(CORE-2) ARE CONNECTED TO

TEED-2 PROTECTION

TEEDTEED--1/ TEED1/ TEED--2 PROTECTION2 PROTECTION1-52CB 2-52CB 3-52CBBUS-1 BUS-2

3

3 3

3

3

LINE-1 AT/F-1

TEED-1&2(BAY 1&2)

TEED-1&2(BAY 2&3)

TEED PROTECTION IS BASED ON KIRCHOFFS CURRENT LAW. THREE SETS OTEED PROTECTION IS BASED ON KIRCHOFFS CURRENT LAW. THREE SETS OF CTSF CTSARE CONNECTED IN STAR FASHION. SOME OF THE CURRENTS MUST BE ZERARE CONNECTED IN STAR FASHION. SOME OF THE CURRENTS MUST BE ZERO. IF ANY O. IF ANY UNBALANCE CURRENTS ARE NOTICED THEN IMMEDIATELY TEED PROTECTION UNBALANCE CURRENTS ARE NOTICED THEN IMMEDIATELY TEED PROTECTION OPERATES. IF TEED PROTECTION BAY 1&2 OPERATED THEN IT TRIPS 1OPERATES. IF TEED PROTECTION BAY 1&2 OPERATED THEN IT TRIPS 1--52CB & 252CB & 2--52CB. 52CB. SIMILARLY IF TEED PROTECTION BAY 2&3 OPERATED THEN IT TRIPS 2SIMILARLY IF TEED PROTECTION BAY 2&3 OPERATED THEN IT TRIPS 2--52CB & 352CB & 3--52CB.52CB.

TEEDTEED--11PROTECTIONPROTECTION

SUMMATION OF INDIVIDUAL PHASES OF T-SHAPED 3 CTs BEFORE REACHING TO RELAY. THE CURRENT

FLOWING THROUGH IN 3-PHASES AFTER SUMMATION IS ZERO DURING BALANCED CONDITION.

HIGH IMPENDENCE THREE PHASE DIFFERENTIAL HIGH IMPENDENCE THREE PHASE DIFFERENTIAL RELAY IS USED AS TEEDRELAY IS USED AS TEED--1 PROTECTION.1 PROTECTION.

TEEDTEED--22PROTECTIONPROTECTION

T- SHAPED 3 CTs ARE CONNECTED TO RELAY. THE RELAY HAVING OPERATING COIL & RESTAIRING

COIL. BASED ON THE DIFFERENTIAL CURRENT FLOWING THROUGH THE OPERATING COIL THE

RELAY OPERATES.LOW IMPEDENCE PERCENTAGE BIASED THREE LOW IMPEDENCE PERCENTAGE BIASED THREE

TERMINAL THREE PHASE DIFFERENTIAL RELAY IS TERMINAL THREE PHASE DIFFERENTIAL RELAY IS USED AS TEEDUSED AS TEED--2 PROTECTION.2 PROTECTION.

TEED PROTECTION TRIP SCHEMETEED PROTECTION TRIP SCHEME

BUS-1 BUS-2

1-52CB 3-52CB2-52CB








ABBABBRADHARADHATEEDTEED--11

ABBABBRADSBRADSBTEEDTEED--22

ABBABBRADHARADHATEEDTEED--11

ABBABBRADSBRADSBTEEDTEED--22




BASICS OF LBB/BFR PROTECTIONBASICS OF LBB/BFR PROTECTIONLOCAL BREAKER BACKUP PROTECTIONLOCAL BREAKER BACKUP PROTECTION

A PROTECTION WHICH IS DESIGNED TO CLEAR A SYSTEM FAULTY BY INITIATING TRIPPING OTHER CIRCUIT BREAKER(S) IN THE CASE OF FAILURE TO TRIP OF THE APPROPRIATE CIRCUIT BREAKER.

IN MODERN NETWORKS THE CRITICAL FAULT CLEARING TIME MAY BE LESS THAN 200ms. HENCE, IF THE FAULT IS NOT CLEARED DUE TO FAILURE OF THE PRIMARY PROTECTIVE RELAYS OR THEIR ASSOCIATED CIRCUIT BREAKER, A FAST ACTING BACK-UP PROTECTIVE RELAY MUST CLEAR THE FAULT.THERE ARE TWO BASIC FORMS.REMOTE BACK-UP.LOCAL BACK-UP.

REMOTE BACKREMOTE BACK--UPUPPROVIDES BACK-UP PROTECTION FOR THE BOTH THE RELAYS

(MAIN-1 & MAIN-2) AND BREAKERS AT REMOTE SUBSTATION.

LOCALLOCAL BACKBACK--UPUPLOCAL BACK-UP PROTECTION CAN BE DEVIDED INTO TWO CATAGORIES.RELAY BACK-UPBREAKER BACK-UP

RELAY BACKRELAY BACK--UPUPz DUPLICATE PRIMARY PROTECTION. i.e ONE IS NON SWITCHED

DISTANCE PROTECTION AND ANOTHER IS SWITCHED DISTANCE SCHEME OR OTHER WISE BOTH SCHEMES CHARECTERSTICS ARE DIFFERENT (QUADRALATERAL, MHO CIRCULAR, TAMOTO & OPTICAL ) OR DIFFERENT MANUFACTURERS(ABB, ALSTOM, SIEMENS, EASUN REYROLL, SEL, GE, NXT PHASE OR BASLER) OR DIFFERENT METHODS (i.eELECTROMECHANICAL, STATIC, NUMERICAL{MICROPROCESSOR &DSP}).

IF MAIN-1 & MAIN-2 ARE NUMERICAL RELAYS BOTH SHOULD BE SEPARATE CHARECTERESTICS AND SEPARATE MODELS AND ALL FEATURES SHOULD BE AVAILABLE IN BOTH SCHEMES AND BOTH RELAYS SHOULD BE 100% REDENDENCY IN ALL ASPECTS

TO INCREASE THE SECURITY, THE CIRCUIT BREAKER HAS TWO TRIP COILS, ONE IS CONNECTED TO MAIN-1 PROTECTION AND ANOTHER IS CONNECTED TO MAIN-2 PROTECTION.

BREAKER BACKBREAKER BACK--UPUPBECAUSE OF THE HIGH COST OF HIGH VOLTAGE CIRCUIT

BREAKERS, IT IS NOT FEASIBLE TO DUPLICATE THEM.IN CASE OF A BREAKER FAILURE THE OTHER CIRCUIT BREAKERS

CONNECTED TO THE SAME BUS AS THE FAULTED BREAKER MUST THERE FORE BE TRIPPED.

LBB/BFR FLOW CHARTLBB/BFR FLOW CHART

MAIN PROTECTIONOPERATED

YES

YES

TRIP MAIN

BREAKER

INITIATEBFR

WAIT FOR FAULT

CLEARENCEAND

FAULT CLEARED

YES

NO

RESETBREAKER FAILURE SCHEME

TRIPBACK-UP

BREAKERS

LBB/BFR TIME COLBB/BFR TIME CO--ORDINATION CHARTORDINATION CHARTFAULT OCCURS

NORMAL CLEARING

INOPERATIVEBREAKER

BREAKER INTURUPTING TIME

PROTECTIVE RELAYFOR EX: DISTANCE RELAY

NORMAL CLEARING TIME

BREAKER FAILURE RELAY START

MARGIN

RESETTING TIME OF THE CURRENT MEASURING UNITS

SET TIME OF THE TIME MEASURING UNIT TRIPPING RELAYTIME

BACK-UP BREAKERINTERUPTING TIME

TOTAL CLEARING TIME OF THE BREAKER FAILURE RELAY

MARGIN

MAXIMUM FAULT CLEARING TIME BEFORE SYSTEM INSTABILITY

~30ms ~60ms

LBB/BFR LOGICLBB/BFR LOGICPHASE L1

PHASE L2/E

PHASE L3

CURRENT INPUTS

~

|||

A/DCONVERTER

&I > ISET

I > ISET

PHASE CURRENT SET POINT

EARTH CURRENT SET POINT

&

CIRCUIT BREAKER FAILURE INITIATE

BINARY INPUT

OUT PUT OF DISTANCE RELAY ORSHORT CIRCUIT CURRENT RELAY

> 1

TIMING/OUTPUT STAGE

0 1

0 1

TIME STAGE T1

TIME STAGE T2

TIME STAGE T2SWITCHED OFF

&

&

&

O

> 1

LEDCB FAILURE

INITIATE

LED

TRIP T2RELAY

ALARM T1 RELAY

LED

TRIP T1 RELAY

LED(PHASE START)

LED(EARTH START)

ALARM RELAY(PHASE START)

ALARM RELAY(EARTH START)

LBB/BFR PROTECTIONLBB/BFR PROTECTION

1-52CB 2-52CB 3-52CBBUS-1 BUS-2

LINE1 AT/F-1

LBB / BFR

RAICA

50ZT

LBB / BFR

RAICA

50ZLBB / BFR

RAICA

50Z LBB/BFR IS LOCAL BREAKER BACKUP PROTECTION/ BREAKER FAILURE RELALBB/BFR IS LOCAL BREAKER BACKUP PROTECTION/ BREAKER FAILURE RELAY.Y. 1No RELAY IS PROVIDED FOR EACH BREAKER.1No RELAY IS PROVIDED FOR EACH BREAKER. THIS IS CURRENT OPERATED RELAY.THIS IS CURRENT OPERATED RELAY. THIS RELAY IS ENERGISED WHEN MASTER TRIP RELAY(86THIS RELAY IS ENERGISED WHEN MASTER TRIP RELAY(86--A & 86A & 86--B) OPERATES B) OPERATES

AND GIVEN SIGNAL TO BREAKER FOR TRIP. AND GIVEN SIGNAL TO BREAKER FOR TRIP. IN THIS RELAY TIME DELAY IS PROVIDED.IN THIS RELAY TIME DELAY IS PROVIDED. THIS RELAY OPERATES WHEN THE BREAKER IS UNDER TROUBLE/ FAILS TO THIS RELAY OPERATES WHEN THE BREAKER IS UNDER TROUBLE/ FAILS TO

OPERATE. OPERATE. AFTER ENERGISED THE RELAY AND TIME DELAY COMPLETES, EVEN CURRENTAFTER ENERGISED THE RELAY AND TIME DELAY COMPLETES, EVEN CURRENT

IS THERE THIS THINKS BREAKER FAIL TO OPERATE AND GIVEN SIGNAL ASIS THERE THIS THINKS BREAKER FAIL TO OPERATE AND GIVEN SIGNAL AS PER PER SCHEME DESCRIBED NEXT PRESENTATION.SCHEME DESCRIBED NEXT PRESENTATION.

11--52 CB LBB/BFR OPERATION52 CB LBB/BFR OPERATION

BUS-1 BUS-2

1-52CB 3-52CB2-52CB

8

6

8

6

-

-

A

A

8

6

8

6

-

-

B

B



INITIALISATION

LBB/BFRLBB/BFRTIMETIME

DELAYDELAY

8

6

8

6

-

-

A

A

8

6

8

6

-

-

B

B

TC-1 TC-2

BUSBAR-1 PROTECTION OPTD

AND BUSBAR-1 ISOLATED

DIRECT TRIP 1&2VIA CARRIER TO

OTHER END

TC-1TC-2


BUS-1 BUS-2

1-52CB 3-52CB2-52CB



INITIALISATION


DELAYDELAY8

6

8

6

-

-

A

A

8

6

8

6

-

-

B

B

TC-1 TC-2



TO 86-B TRIP RELAYOF LINE CB(1-52CB)

DIRECT TRIP 1&2VIA CARRIER

TO OTHER END

TO 86-B TRIP RELAYOF AT/F(ICT) CB

(3-52CB)

INTER TRIP TOLVCB & TBCCB


BUS-1 BUS-2

1-52CB 3-52CB2-52CB

8

6

8

6

-

-

A

A

8

6

8

6

-

-

B

B



INITIALISATION


DELAYDELAY

8

6

8

6

-

-

A

A

8

6

8

6

-

-

B

B

TC-1 TC-2 TC-1TC-2

BUSBAR-2PROTECTION OPTD

AND BUSBAR-2 ISOLATED

INTER TRIP TO LV CB & TBC CB

AUTO RECLOSURE BASICSAUTO RECLOSURE BASICS FAULTS ARE THREE TYPES

1. TRANSIENT FAULT: These are cleared by the immediate tripping of Circuit Breakers and do not reoccur when the line is re-energized.2. SEMI-PERMANENT FAULTS: These require a time interval to disappear before a line is charged again.3. PERMANENT FAULTS: These are to be located and repaired before the line is re-energized.

About 80-90% of the faults occurring are transient in nature. Hence the Automatic Reclosure of breaker (after tripping on Fault) will result in the line being successfully re-energized.

ADVANTAGES:A. Decreasing outage time.B. Improving Reliability.C. Improving system stability.D. Reduce fault damage and Maintenance Time.

DEAD TIME: The time between the Auto-reclosing Scheme being energized and the operation of the contacts which energize the Circuit Breaker closing circuit.

RECLAIM TIME: The Time Following a successful closing operation measured from the instant the Auto-Reclosing relay closing contacts make which must elapse before the Auto-Reclosing relay initiates another reclosing attempt. In other words, it may be said to be the time between 1st and 2ndAuto-Reclosure.

TYPES OF AUTO-RECLOSING SCHEMES:1. BASED ON PHASE

A. THREE PHASE AUTO-RECLOSING: This type of Auto-Reclosing causes an immediate drift part of the two systems and hence no interchange of synchronizing power can take place during the dead time. B. SINGLE PHASE AUTO-RECLOSING: In this, only the faulty phase(only SLG Faults) is reclosed without causing interruption in interchange synchronizing power between two systems through other two healthy phases.

2. BASED ON ATTEMPTS OF RECLOSUREA. SINGLE SHOT AUTO-RECLOSING: In this scheme, Breaker is reclosed only once on a given fault before lockout of Circuit Breaker Occurs. High-Speed Auto-Reclosing for EHT System is invariably Single Shot.B. MULTI-SHOT AUTO-RECLOSING: In this scheme, more than one reclosing attempts made for a given fault before lockout of Circuit Breaker occurs.B.I. DISADVANTAGES: Repeated closure attempts has with high fault level would seriously affect the Circuit Breaker, Equipment and System Stability.B.ii. CIRCUIT BREAKER LIMITATIONS: Ability of Circuit Breaker to Perform several Trip Close operations in quick succession. B. iii. SYSTEM CONDITIONS: In the percentage of the semi-Permanent faults (which could be burnt out) is moderate, For example on the lines through the forest, multi shot Auto-Reclosing is followed.

3. DEPENDING ON SPEED:A. HIGH-SPEED AUTO-RECLOSING: This aids in fast restoration of supply but should be done by taking into account the following factors.I. System disturbance time can be tolerated without loss of system stability.ii. Characteristics of Protection Schemes and Circuit Breaker. B. LOW SPPED OR DELAYED AUTO RECLOSING: This is suitable for highly interconnected systems where the loss of a single line is unlikely to cause two sections of the system to drift apart and loose synchronism.

METHOD OF ADOPTION IN ONE AND HALF BREAKER SYSTEM: The Auto-Reclosure Functions used for the Bus Breakers 1-52CB & 3-52CB are set as Masters and one for the Center Breaker 2-52CB(TIE) as Follower. Co-ordination is required between the Auto-Reclosure Functions. A Synchrocheck function is also loaded in each Relay to permit 3 pole Auto-Reclosing.Each Line Protection relays starts both MAIN & TIE Circuit Breakers to trip for the Concerned line. After a Successful reclosure of the Main Breaker, The Tie Breaker will be reclosed after a supplementary time delay. Should the Main CB Auto-Reclosure relay not be successful in its reclosing attempts, the Tie CB Auto-Reclosure is blocked. If the Main CB is Open or its Auto-Reclosure Relay is not ready or Out of service, The TIE CB Auto-Reclosure will reclose The TIE Breaker after its own dead time without any supplementary time delay.

CHOICES OF EHV SYSTEM:1. CHOICE OF DEAD TIME: A. Lower limit is decided by deionising of Circuit Breaker.B. Upper Limit is decided by Transient Stability and Synchronism.C. Longer Transmission Lines Require Longer dead Time.D. The dead time for High Speed Auto-Reclosing scheme with EHV System is 0.3 to 1.2 sec.2. CHOICE OF RECLAIM TIME:This should not be set to such a low value that the operating cycle of Breaker is exceeded when two faults incident occurs close together. The reclaim time will be in the range of 10 to 30 sec., depending the breaker opening and closing mechanisms.3. CHOICE OF ZONE:This should normally kept in Zone-1. It is a Zone-1 fault and SLG fault only auto-reclosure is comes in to picture. In other zones the auto reclosure is blocked.

AUTOAUTO--RECLOSURE FOR RECLOSURE FOR ONE & HALF BREAKER SCHEMEONE & HALF BREAKER SCHEME

1-52CB 2-52CB 3-52CB

21 L121 L1MAINMAIN--1 1 REL 521REL 521




LINE-1 LINE-2

79 (A/R)+79 (A/R)+25(SYNC) 25(SYNC) RAAAMRAAAMRASCRASC



TRIP COMMANDSAUTO RECLOSURE

COMMANDS

AUTO RECLOSING TIMING CHARTAUTO RECLOSING TIMING CHART

TIME

AUTO RECLOSERELAY

INSTANT OF FAULT

PROTECTION

CIRCUIT BREAKERT

R

A

N

S

I

E

N

T

F

A

U

L

T

P

E

R

M

A

N

E

N

T

F

A

U

L

T

PROTECTION

CIRCUIT BREAKER

OPERATING TIME

OPERATING TIME

OPERATES

OPERATES

TRIP COILENERGISED

CONTACTSSEPARATE

ARCEXTINGUISHED

CONTACTS FULLY OPEN

RESETS

TRIP COILENERGISED

CONTACTSSEPARATE

ARCEXTINGUISHED

CONTACTS FULLY OPEN

RESETS

OPENING TIME

ARCING TIME

OPERATING TIME

OPENING TIME

ARCING TIME

OPERATING TIME

CLOSING COILENERGISED

CONTACTS MAKE

CONTACTSFULLY CLOSED

CLOSINGTIME

DEAD TIME

CLOSING COILENERGISED

CONTACTS MAKE

CONTACTSFULLY CLOSED

CLOSINGTIME

DEAD TIME

RECLOSE ON TO FAULT

OPERATES

TRIP COILENERGISED

CONTACTSSEPARATE

ARCEXTINGUISHED

CONTACTS FULLY OPEN

RESETS

SYSTEM DISTURBANCE TIMERECLOSE INITIATED

BY PROTECTION

DEAD TIME CLOSING PULSE TIMERECLAIM TIME

RELAY READY TO RESPONDTO FURTHER FAULT INCIDENTS(AFTER SUCEESFUL RECLOSRE)

CARRIER CARRIER INTERTRIPPING INTERTRIPPING

SCHEMESSCHEMESADOPTED IN ADOPTED IN


SCHEME SCHEME PREPARED BY


PROTECTION COUPLER PANELPROTECTION COUPLER PANEL

C

E

DISPLAY

ACTIVE START TRIP

NSD 50/ NSD 50/ NSD 70NSD 70

G4AC TB: V9LC

11--

2+2+

55--

6+6+

99--

10+

1313--

14+14+

TXTXTRIP TRIP A(C)A(C)

RXRXTRIPTRIPA(C)A(C)

TXTXTRIPTRIPB(D)B(D)

RXRXTRIPTRIPB(D)B(D)

CS

CS

CR

CR

GA4D TB:V9LC

11--

2+2+

55--

6+6+

99--

10+10+

13-

14+14+

TXTXTRIP TRIP C(A)C(A)

RXRXTRIPTRIPC(A)C(A)

TXTXTRIPTRIPD(B)D(B)

RXRXTRIPTRIPD(B)D(B)

CS

CS

CR

CR

G4AA TB: V9LB

A

L

A

R

M

A

L

A

R

M

-

-

1

1

2

5

0

V

D

C

2

5

0

V

D

C

A

L

A

R

M

A

L

A

R

M

-

-

2

2

2

5

0

V

D

C

2

5

0

V

D

C

55

66

77

88

PROTECTION COUPLERS FOR 400KV LINEPROTECTION COUPLERS FOR 400KV LINE FOR EACH LINE 2Nos PROTECTION COUPLER PANELS PROVIDED.FOR EACH LINE 2Nos PROTECTION COUPLER PANELS PROVIDED. FOR EACH LINE 1NO CARRIER SPEECH PANEL PROVIDED.FOR EACH LINE 1NO CARRIER SPEECH PANEL PROVIDED. SO, 1 LINE REQUIRES TOTAL 3 PANELS.SO, 1 LINE REQUIRES TOTAL 3 PANELS. CARRIER SPEECH PANEL PURELY FOR VOICE COMMUNICATION BETWEEN CARRIER SPEECH PANEL PURELY FOR VOICE COMMUNICATION BETWEEN

TWO SUBSTATIONS, i.e THE LINE CONNECTED SUBSTATIONS.TWO SUBSTATIONS, i.e THE LINE CONNECTED SUBSTATIONS. THE VOICE COMMUNICATION ARE TWO METHODS PROVIDED.THE VOICE COMMUNICATION ARE TWO METHODS PROVIDED. ONE IS HOTLINE COMMUNICATION/DEDICATED/ LIFT&TALK METHOD.ONE IS HOTLINE COMMUNICATION/DEDICATED/ LIFT&TALK METHOD. ANOTHER IS DIAL METHOD.ANOTHER IS DIAL METHOD. IN PROTECTION COUPLER PANELIN PROTECTION COUPLER PANEL--1 TOTAL 3 CARDS ARE IMPORTANT FOR 1 TOTAL 3 CARDS ARE IMPORTANT FOR

SENDING & RECEIVING TRIP SIGNALS.SENDING & RECEIVING TRIP SIGNALS. ONE CARD FOR ALARM i.e G4AA. ONE CARD FOR PERMISSIVE/PROTECTION ONE CARD FOR ALARM i.e G4AA. ONE CARD FOR PERMISSIVE/PROTECTION

TRIP i.e G4AC & ANOTHER CARD FOR DIRECT TRIPS i.e G4AD.TRIP i.e G4AC & ANOTHER CARD FOR DIRECT TRIPS i.e G4AD. IN PROTECTION COUPLERIN PROTECTION COUPLER--2 PANEL ALSO 3 CARDS ARE PROVIDED SIMILAR TO 2 PANEL ALSO 3 CARDS ARE PROVIDED SIMILAR TO

PROTECTION COUPLERPROTECTION COUPLER--1 PANEL.1 PANEL. THE PROTECTION COUPLER PANEL DRAWING IS SHOWN IN PREVIOUS MENU.THE PROTECTION COUPLER PANEL DRAWING IS SHOWN IN PREVIOUS MENU. 1SET TX & RX FOR PERMISSIVE/ PROTECTION TRIP(G4AC)1SET TX & RX FOR PERMISSIVE/ PROTECTION TRIP(G4AC) 1SET TX & RX FOR BACKUP FOR PERMISSIVE/ PROTECTION IN ANOTHER 1SET TX & RX FOR BACKUP FOR PERMISSIVE/ PROTECTION IN ANOTHER

PANEL(G4AC).PANEL(G4AC). 1SET TX & RX FOR DIRECT TRIP CHANNEL1SET TX & RX FOR DIRECT TRIP CHANNEL--1( G4AD).1( G4AD). 1SET TX & RX FOR SPARE UNDER EMERGENCY(G4AD).1SET TX & RX FOR SPARE UNDER EMERGENCY(G4AD). THE ABOVE ARRANGEMENT SIMILAR FOR PROTECTION COUPLER PANELTHE ABOVE ARRANGEMENT SIMILAR FOR PROTECTION COUPLER PANEL--2.2. G4AA CARD FOR ALARM.G4AA CARD FOR ALARM.

MAINMAIN--1 PROTECTION CARRIER INTER TRIPPING1 PROTECTION CARRIER INTER TRIPPING

ABB REL521ABB REL521CR

CS

-VECARRIER RECEIVE

CARRIER SEND

ALARM

IN

A

B

B

A

B

B

N

S

D

5

0

N

S

D

5

0

OUT

PANEL-1

PANEL-2

G4AC V9LC 1

G4AC V9LC 2

G4AC V9LC 5

G4AC V9LC 6

G4AA V9LB 5

G4AA V9LB 6

A

B

B

A

B

B

N

S

D

5

0

N

S

D

5

0 G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

G4AC V9LC 13THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIPTHIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIPAND CONNECTED IN ANOTHER PANELAND CONNECTED IN ANOTHER PANEL

+VE -VE

MAINMAIN--2 PROTECTION CARRIER INTER TRIPPING2 PROTECTION CARRIER INTER TRIPPING

ABB REL316ABB REL316CR

CS

-VECARRIER RECEIVE

CARRIER SEND

ALARM

IN

A

B

B

A

B

B

N

S

D

5

0

N

S

D

5

0

OUT

PANEL-2

PANEL-1

G4AC V9LC 1

G4AC V9LC 2

G4AC V9LC 5

G4AC V9LC 6

G4AA V9LB 5

G4AA V9LB 6

A

B

B

A

B

B

N

S

D

5

0

N

S

D

5

0 G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

G4AC V9LC 13THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIPTHIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIPAND CONNECTED IN ANOTHER PANELAND CONNECTED IN ANOTHER PANEL

+VE -VE

DIRECT TRIP SEND CARRIER CHANNELDIRECT TRIP SEND CARRIER CHANNEL--11

T N C

MAIN CB(1-52CB)

T N C

TIE CB(2-52CB)

CONTROL PANEL

BUSBAR TRIP (ZONE-1)


BUSBAR PROT-1 PANEL

BUSBAR PROT-2 PANEL

R Y B

R Y B

TIE CB (2-52 CB)

MAIN CB (1-52 CB)

50 LBB/BFR FOR MAIN CB

RAICA

59L1

OVER VOLTAGE STAGE-1

59L2


50 LBB/BFR FOR TIE CB

RAICA

ABBABBNSD 50NSD 50DC +VE

FROM PANEL

G4AD V9LC 2

DC VE FROM PANEL

G4AD V9LC 1

PANEL-1

DIRECT TRIP SEND CARRIER CHANNELDIRECT TRIP SEND CARRIER CHANNEL--22

T N C

MAIN CB(1-52CB)

T N C

TIE CB(2-52CB)

CONTROL PANEL



BUSBAR PROT-1 PANEL

BUSBAR PROT-2 PANEL

R Y B

R Y B

TIE CB (2-52 CB)

MAIN CB (1-52 CB)

50 LBB/BFR FOR MAIN CB

RAICA

59L1


59L2


50 LBB/BFR FOR TIE CB

RAICA

ABBABBNSD 50NSD 50DC +VE

FROM PANEL

G4AD V9LC 2

DC VE FROM PANEL

G4AD V9LC 1

PANEL-2

DIRECT TRIP RECEIVE CHANNELDIRECT TRIP RECEIVE CHANNEL--1&21&2

ABBABBNSD 50NSD 50

G4AD V9LC 6

G4AD V9LC 5

ABBABBNSD 50NSD 50

G4AD V9LC 6

G4AD V9LC 5

PANEL-1

PANEL-2

DC +VE

DC +VE

+VE -VE

TO 86TO 86--A MASTER TRIP RELAY A MASTER TRIP RELAY (HIGH SPEED TRIP RELAY) FOR (HIGH SPEED TRIP RELAY) FOR MAIN CB(152CB)MAIN CB(152CB)TO 86TO 86--A MASTER TRIP RELAYA MASTER TRIP RELAY(HIGH SPEED TRIP RELAY) FOR (HIGH SPEED TRIP RELAY) FOR TIE CB(252CB)TIE CB(252CB)

TO 86TO 86--B MASTER TRIP RELAYB MASTER TRIP RELAY(HIGH SPEED TRIP RELAY) FOR(HIGH SPEED TRIP RELAY) FORMAIN CB(152CB)MAIN CB(152CB)

TO 86TO 86--B MASTER TRIP RELAY B MASTER TRIP RELAY (HIGH SPEED TRIP RELAY) FOR(HIGH SPEED TRIP RELAY) FORTIE CB(252CB)TIE CB(252CB)

DIRECT TRIP-1CARRIER RECEIVE RELAY

DIRECT TRIP-2CARRIER RECEIVE RELAY

PLCC CARRIER PROTECTION SYSTEMPLCC CARRIER PROTECTION SYSTEM(TELEPROTECTION)(TELEPROTECTION)

C

E

ABB Network Partner AG REL531

REL 521MAIN-1

PROTECTION

C

E

1

2345678

9

10111213141516

ABB Network Partner AG REC 316*4

C

E

1

2345678

9

10111213141516


C

E


REL 316MAIN-2

PROTECTION

PLCCPANEL

PLCCPANEL

NSD 50PANEL

NSD 50PANEL

NSD 50PANEL

NSD 50PANEL

ELECTRICAL CONNECTION


ELECTRICAL POWER LINE

FIBRE OPTIC PROTECTION SYSTEMFIBRE OPTIC PROTECTION SYSTEM(TELEPROTECTION)(TELEPROTECTION)

C

E


REL 521MAIN-1

PROTECTION

C

E

1

2345678

9

10111213141516


C

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1

2345678

9

10111213141516


C

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REL 316MAIN-2

PROTECTION

NSD 70PANEL

NSD 70PANEL

NSD 70PANEL

NSD 70PANEL



FOX-UFOX-515

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FIBRE OPTIC CARRIER PROTECTION SYSTEMFIBRE OPTIC CARRIER PROTECTION SYSTEM(TELEPROTECTION)(TELEPROTECTION)

DIGITAL RELAY CONNECTION VIA FIBRE OPTICDIGITAL RELAY CONNECTION VIA FIBRE OPTIC

FOX-UFOX-515

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M

FOX-UFOX-515

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REL 521MAIN-1

PROTECTION

C

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1

2345678

9

10111213141516


C

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1

2345678

9

10111213141516


C

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REL 316MAIN-2

PROTECTION

MAINMAIN--1 & MAIN1 & MAIN--22PROTECTION FORPROTECTION FOR

AUTO TRANSFORMER AUTO TRANSFORMER ADOPTED IN ADOPTED IN




BASICS OF TRANSFORMER PROTECTIONBASICS OF TRANSFORMER PROTECTION1. 1. PURPOSE OF POWER TRANSFORMER PROTECTIONPURPOSE OF POWER TRANSFORMER PROTECTION

POWER T/F PROTECTION IS USUALLY INSTALLED TO DISCONNECT THE T/F AT:A.A. INTERNAL SHORT CIRCUITS AND EARTH FAULTS IN THE T/F AND ITS CONNECTED CIRCUITS.B.B. EXTERNAL FAULTS ON OTHER CIRCUITS. (BACK-UP PROTECTION)C.C. ABNORMAL SERVICE CONDITIONS SUCH AS OVERLOAD & OVER VOLTAGE.

2.2. PROTECTION DEVICES INBUILT OR MOUNTED ON POWER T/FPROTECTION DEVICES INBUILT OR MOUNTED ON POWER T/FA.A. OIL IMMERSED POWER T/F USUALLY HAVE A GAS DETECTOR AND OIL SURGE. DETECTOR (BUCHHOLZ ALARAM & TRIP DEVICES), WHICH ARE EXCELLENT FOR DETECTING INTERNAL FAULTS.B.B. LOAD TAPCHANGER COMPARTMENTS MAY HAVE A SIMILAR OVER PRESSURE DEVICE. C.C. TEMPARATURE MONITORS FOR OIL & WINDING PROVIDE GOOD OVER LOAD PROTECTION.D.D. PRESSURE RELIEF DEVICE IS PROVIDED TO SAFE GUARD THE T/F FROM HIGH PRESURES.

3.3. TRANSFORMER DIFFERENTIAL PROTECTIONTRANSFORMER DIFFERENTIAL PROTECTIONIT IS WIDELY USED AS INSTANTANEOUS PROTECTION FOR SHORT CIRCUIT FAULTS WITH IN THE DIFFERENTIAL ZONE. THIS IS TREATED AS MAIN-1 PROT FOR T/F.THE MOST COMMON TYPE OF PROTECTION IS THE CURRENT RESTRAINT TYPE.SOME TYPE OF DIFFERENTIAL RELAYS REQUIRE INTERPOSING CTs FOR CT RATIO MATCHING AND/OR PHASE SHIFT.HIGH IMPEDENCE DIFFERENTIAL PROTECTION CAN BE USED ON AUTO T/F & REACTORS.IT COVERS ONE GALVANICALLY INTERCONNECTED WINDING (WDG DIFF). BUT NOT A SEPARATE TERTIARY WINDING. IT REQUIRES A THREE PHASE SET OF CTs AT THE NEUTRAL SIDE OF WINDING.

4.4. RESTRICTED EARTH FAULT PROTECTIONRESTRICTED EARTH FAULT PROTECTIONTHIS IS A HIGH IMPEDENCE DIFFERENTIAL EARTH FAULT PROTECTION FOR ONE WINDING OR 1-PH. IT IS SOME TIMES USED IN LOW IMPEDENCE EARTHED SYSTEMS TO GIVE AN INSTANTANEOUS PROTECTION. WHICH IS MORE SENSITIVE THAN THE TRANSFORMER DIFFERENTIAL ONE. TYPICAL SENSITIVITY IS 5%. THERE ARE SOME PARTICULAR CT REQUIREMENTS, e.g. EQUAL TURNS RATIO OF THE CTs. INCASE OF T/F HAVING EARTHED STAR WINDING ONE RELAY SUFFICIENT. T/F HAVING STAR/STAR (BOTH EARTHED) APPLY TWO INDEPENDENT RELAYS.

5.5. BACK UP PROTECTIONBACK UP PROTECTIONA VARIETY OF RELAYS ARE AVAILABLE.A.A. OVER CURRENT & EARTH FAULT PROTECTION. ( 50, 50N, 51, 51N, 67, 67N - ANY COMBINATION OF THESE)B.B. UNDER IMPEDENCE / DISTANCE ( Z).

6.6. OTHER TYPES OF RELAYSOTHER TYPES OF RELAYSA.A. OVER VOLTAGE RELAY (U >).B.B. OVER FLUX/ EXCITATION (V/F >)( INVERSE TIME & DIFENITE TIME). FOR 400KV/220KV, 315 MVA & 500MVA TRANSFORMERS BOTH SIDES( i.e HV & LV) OVER FLUX RELAYS ARE PROVIDED BECAUSE BOTH SIDES HAVING GRID.

NORMALLY ADOPTED POWER TRANSFORMERS CAPACITIES IN NORMALLY ADOPTED POWER TRANSFORMERS CAPACITIES IN 400KV / 220KV400KV / 220KV

CAPACITY OF CAPACITY OF TRANSFORMERTRANSFORMER

HV HV VOLTAGEVOLTAGE

HV HV CURRENTCURRENT

LV LV VOLTAGEVOLTAGE

LV LV CURRENTCURRENT

315 MVA315 MVA 400 KV400 KV 454.68 A454.68 A 220 KV220 KV 0826.68 A0826.68 A500 MVA500 MVA 400 KV400 KV 721.71 A721.71 A 220 KV220 KV 1312.20 A1312.20 A

NORMS OF PROTECTION FOLLOWED IN APTRANSCO NORMS OF PROTECTION FOLLOWED IN APTRANSCO FOR POWER TRANSFORMERS & AUTO TRANSFORMERSFOR POWER TRANSFORMERS & AUTO TRANSFORMERS

BACK UPBACK UPPROTECTIONPROTECTIONS.NoS.No CAPACAPACITYCITY

VOLTAGE VOLTAGE RATIORATIO

MAIN MAIN PROTECTIONPROTECTION

HVHV

ADDITIONAL ADDITIONAL PROTECTIONPROTECTION

3 OL + 3 OL + 1 DIR EL1 DIR EL

BUCHHOLZ, BUCHHOLZ, OLTC OSROLTC OSROIL TEMPOIL TEMP

WDNG TEMPWDNG TEMP

BUCHHOLZBUCHHOLZOVER FLUX OVER FLUX OLTC OSROLTC OSRPRV/PRDPRV/PRDOIL TEMPOIL TEMP

WDNG TEMPWDNG TEMP

3 OL + 3 OL + 1 DIR EL1 DIR EL

3 OL + 3 OL + 1 DIR EL1 DIR EL3 OL + 3 OL +

1 DIR EL1 DIR EL

SPECIALSPECIALPROTECTIONPROTECTION

11 7.5 MVA 7.5 MVA 16 MVA16 MVA

3 DIR OL 3 DIR OL (HIGHSET) + (HIGHSET) +

1 DIR EL1 DIR EL(HIGHSET)(HIGHSET)

LVLV

132KV/11KV132KV/11KV 3 OL +3 OL +1 EL 1 EL

3 OL +3 OL +1 EL 1 EL

3 OL +3 OL +1 EL 1 EL

3 OL +3 OL +1 DIR EL 1 DIR EL 3 DIR OL 3 DIR OL

(HIGHSET) + (HIGHSET) + 1 DIR EL1 DIR EL

(HIGHSET) (HIGHSET)

132KV/33KV132KV/33KV

220KV/33KV220KV/33KV

220KV/132KV220KV/132KV

400KV/220KV400KV/220KV

DIFFERENTIAL DIFFERENTIAL RELAYRELAY

2216 MVA16 MVA

31.5 MVA31.5 MVA50 MVA50 MVA

NIL NIL

REF RELAY,REF RELAY,OVER LOAD OVER LOAD

ALARM ALARM RELAYRELAY

33 31.5 MVA31.5 MVA50 MVA50 MVA

44 100 MVA100 MVA

5 5 315 MVA 315 MVA 500 MVA500 MVA

MAINMAIN--1/ DIFFERENTIAL PROTECTION FOR AT/F1/ DIFFERENTIAL PROTECTION FOR AT/F(4 CT METHOD)(4 CT METHOD)

3 3 3

3 3 3

3-CT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

2-ACT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

5S4 5S4 5S4

5S35S3 5S3

P2P2P2 CT MB

CT MB

P2P2P2

5S4 5S4 5S4

5S35S3 5S3

3 3 3

LV-CT

CORE-5CTR: 1200-800/1A

CLASS: PS

5S1 5S1 5S1

5S35S3 5S3

P2P2P2

CT MB

C

E

DISPLAY

ACTIVE START TRIP

RET 521/ RET 521/ RET 316RET 316RADSBRADSB

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NORMALLY LOW IMPEDENCE BIASED

DIFFERENTIAL RELAY IS USED FOR

TRANSFORMER DIFFERENTIAL PROTECTION

MAINMAIN--1/ DIFFERENTIAL PROTECTION FOR AT/F1/ DIFFERENTIAL PROTECTION FOR AT/F(5 CT METHOD)(5 CT METHOD)

3 3 3

3-TCT

CORE-5CTR: 2000-1000-500/1A

CLASS: PS

5S4 5S4 5S4

5S35S3 5S3

P2P2P2 CT MB3 3 3

LV-CT

CORE-5CTR: 1200-800/1A

CLASS: PS

5S1 5S1 5S1

5S35S3 5S3

P2P2P2

CT MB

C

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DISPLAY

ACTIVE START TRIP

RET 521/ RET 521/ RET 316RET 316RADSBRADSB

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A

SELECTION OF AUX.CTs FOR DIFFERENTIAL PROTECTIONSELECTION OF AUX.CTs FOR DIFFERENTIAL PROTECTION NORMALLY 400KV/220KV AUTO TRANSFORMERS ARE OF CAPACITY 315MVA.NORMALLY 400KV/220KV AUTO TRANSFORMERS ARE OF CAPACITY 315MVA. FOR MERZ PRICE PROTECTION IF TRANSFORMER IS CONNECTED IN STAR/STFOR MERZ PRICE PROTECTION IF TRANSFORMER IS CONNECTED IN STAR/STARAR

THEN CT SECONDARIES ARE TO BE CONNECTED IN DELTA/DELTA.THEN CT SECONDARIES ARE TO BE CONNECTED IN DELTA/DELTA. CORRECT RATIO CTs ARE NOT AVAILABLE, THEN AUX.CTs ARE TO BE PROVCORRECT RATIO CTs ARE NOT AVAILABLE, THEN AUX.CTs ARE TO BE PROVIDEDIDED

FOR ACHEVING SUITABLE CURRENTS.FOR ACHEVING SUITABLE CURRENTS. IF AUX CTs ARE USING THEN MAIN CT SECONDARIES ARE CONNECTED IN SIF AUX CTs ARE USING THEN MAIN CT SECONDARIES ARE CONNECTED IN STAR.TAR. THIS IS BROUGHT TO AUX CTs. AUX CTs PRIMARY IS CONNECTED IN STATHIS IS BROUGHT TO AUX CTs. AUX CTs PRIMARY IS CONNECTED IN STAR & R &

SECONDARIES ARE CONNECTED IN DELTA.SECONDARIES ARE CONNECTED IN DELTA. NORMALLY THE RELAY RATED CURRRENT IS 1A.NORMALLY THE RELAY RATED CURRRENT IS 1A. AUX.CT s SECONDARIES ARE CONNECTED IN DELTA. FOR ACHIEVING 1A TOAUX.CT s SECONDARIES ARE CONNECTED IN DELTA. FOR ACHIEVING 1A TO

RELAY, AUX.CT SECONDARY CURRENT IS RELAY, AUX.CT SECONDARY CURRENT IS TO BE TO BE 0.577A.0.577A. THE FULL LOAD PRIMARY CURRENT OF 315MVA AT/F IS 454.7A.THE FULL LOAD PRIMARY CURRENT OF 315MVA AT/F IS 454.7A. BUT THE 400KV CTs RATIOs ARE AVAILABLE : 2000BUT THE 400KV CTs RATIOs ARE AVAILABLE : 2000--10001000--500/1A500/1A NEAREST VALUE TO FULL LOAD CURRENT IS 500/1A. HENCE IT IS ADOPTENEAREST VALUE TO FULL LOAD CURRENT IS 500/1A. HENCE IT IS ADOPTED.D. HENCE AT FULL LOAD HV CURRENT i.e 454.7A, THEN SECONDARY OF CT HENCE AT FULL LOAD HV CURRENT i.e 454.7A, THEN SECONDARY OF CT

CURRENT WILL BE 0.91A.CURRENT WILL BE 0.91A. SO HV SIDE AUX.CT RATIO IS 0.91/0.577A.SO HV SIDE AUX.CT RATIO IS 0.91/0.577A. THE FULL LOAD SECONDARY CURRENT OF 315MVA AT/F IS 826.7A.THE FULL LOAD SECONDARY CURRENT OF 315MVA AT/F IS 826.7A. BUT THE 220KV CTs RATIOs ARE AVAILABLE: 1200BUT THE 220KV CTs RATIOs ARE AVAILABLE: 1200--800/1A.800/1A. NEAREST VALUE TO FULL LOAD CURRENT IS 1200/1A. HENCE IT IS ADOPTNEAREST VALUE TO FULL LOAD CURRENT IS 1200/1A. HENCE IT IS ADOPTED.ED. HENCE AT FULL LOAD LV CURRENT i.e 826.7A,THEN SECONDARY OF CT CUHENCE AT FULL LOAD LV CURRENT i.e 826.7A,THEN SECONDARY OF CT CURRENT RRENT

WILL BE 0.689A.WILL BE 0.689A. SO LV SIDE AUX CT RATIO IS 0.689/0.577A.SO LV SIDE AUX CT RATIO IS 0.689/0.577A. SPECIAL INFORMATION:SPECIAL INFORMATION: LATEST NUMERICAL RELAYS NEED NOT REQUIRE AUX LATEST NUMERICAL RELAYS NEED NOT REQUIRE AUX

CTs. IN THESE RELAYS, CT RATIOS MATCHING CAN BE PROGRAMMED.CTs. IN THESE RELAYS, CT RATIOS MATCHING CAN BE PROGRAMMED.

MAINMAIN--2/ BACKUP PROTECTION FOR AT/F HV2/ BACKUP PROTECTION FOR AT/F HV(4 CT METHOD)(4 CT METHOD)

400kv protection_ gk

Documents

trip coil

inturupting line

main bay

tie bay

circuit breakers

feeding paths

middle breaker2

89l31ctp2 p13