transfer bus

P. GOPALA KRISHNAADE/400KV/APTRANSCO

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. In This Two Main Buses Are Available.2. They Are Called Bus-1 & Bus-2.3. One More Bus Is Available. This is Not Main Bus. 4. We Call As Transfer Bus Or Auxiliary Bus Or Temporary Bus.5. This is Useful only, When any Of the Circuit Breaker (only One) Is Out Of Service Or

Maintenance Or Trouble.6. If One Of the Circuit Breaker in Trouble, This Is More Useful.7. If Second Circuit Breaker is also in Trouble, then This Is Not Useful.8. Most Of The Time, The Auxiliary Bus Is Kept Open. 9. Based On My Experience, Now a Days, this May Be Least Useful.10. Note: Checking of Every Month, One Day, One Feeder is to be Kept On Transfer Bus and to

Ascertain Healthiness Of Transfer Bus. This is to be Followed Regularly, Then the Transfer Bus is Available When Emergency Occurs.

11. But, this System is Not Useful For CT Troubles or any other Equipment Troubles. 12. The Tentative Substation Layout Is Shown In Next Slide.13. This System is adopted When ABCBs, BOCBs, MOCBs Are Available.14. The ABCBs, BOCBs, MOCBs Requires Regular Maintenance.15. The reason behind for Adoption of Transfer Bus System is, During The Maintenance of

Circuit Breaker, the Consumer Should Not Suffer.16. Now A Days SF6 CBs With Trouble Free Mechanisms are Coming and all Substations are

having Redundant or Alternative Source of supply is Available, Still Following This Concept is Some What Unhappy.

17. The Location of CT is after Line Isolator and towards Line. This is also one more Disadvantage.

18. For Maintenance Of CT, The Line is to be Taken LC and Remove the Jumpers And to Test. 19. This Type Of One More Unhappy System Is Available i.e. Double Bus With Bypass Isolator.

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

FEEDER1

BUS-2

BUS-1

FEEDER2

TRA

NSF

ER B

US

CO

UPL

ER

T/F-1 T/F-2

BU

S C

OU

PLER

TRANSFER BUS

FEEDER3 FEEDER4

BAY1 BAY2BAY3 BAY4 BAY5

BAY6 BAY7 BAY8

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. In this each Feeder / Transformer / Reactor is having one Circuit Breaker.2. One Circuit Breaker for Bus Coupler.3. One more Circuit Breaker for Transfer Bus Coupler.4. The details are as follows based on layout.5. CB designation is very specific.6. First number will show voltage level. For 765 KV - 7, 550KV-5, 400KV -4, 220KV-2, 132KV -1.7. Second number will show Bay number. 8. 52 is ANSI code for CB. Some of the locations it is called Q0.

2 – 7 – 52 CBFEEDER – 3BAY – 72 – 6 – 52 CBTRANSFER BUSBAY – 6

2 – 8 – 52 CBFEEDER – 4BAY – 8

2 – 5 – 52 CBTRANSFORMER – 2BAY – 52 – 4 – 52 CBBUS COUPLERBAY – 42 – 3 – 52 CBTRANSFORMER – 1BAY – 32 – 2 – 52 CBFEEDER – 2BAY – 22 – 1 – 52 CBFEEDER – 1BAY – 1

CB DESIGNATIONCIRCUITBAY NO


1. FOR BUS ISOLATON: EACH BUS HAVING BUS ISOLATOR FOR EACH BAY.

2. FOR CB ISOLATION: CIRCUIT BREAKER HAVING BOTH SIDES ISOLATORS.

3. FOR LINE/ICT ISOLATION: LINE / ICT HAVING LINE ISOLATOR.

4. FOR BUS MAINTANENCE: EACH BUS HAVING BUS EARTH SWITCH.

5. FOR CB MAINTANENCE: EACH ISOLATOR HAVING EARTH SWITCH TOWARDS CB SIDE.

6. FOR LINE / ICT MAINTANENCE: EACH LINE / ICT HAVING LINE EARTH SWITCH.

STANDARD PRACTICE

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. In this each Feeder / Transformer / Reactor is having four Isolators.2. One Isolator for Bus-1, one Isolator for Bus-2, one isolator for Transfer Bus and another

Isolator for Feeder / Transformer / Reactor.3. In case of Bus Coupler only Bus-1 & Bus-2 Isolators will be available.4. In case of Transfer Bus Coupler, Bus-1, Bus-2 & Transfer Bus isolators are available.5. 89 represents Isolator. Bus-1 Isolator represents-A, Bus-2 Isolator represents-B, Transfer

Bus Isolator represents-C, Circuit Isolator represents-L/T/R based on circuit.

2-8-89B2-7-89B2-6-89B2-5-89B2-4-89B2-3-89B2-2-89B2-1-89BBUS-2

2-8-89C2-7-89C2-6-89C2-5-89C

-2-3-89C2-2-89C2-1-89CTR BUS

2-8-89A2-7-89A2-6-89A2-5-89A2-4-89A2-3-89A2-2-89A2-1-89ABUS-1

ISOLATORS DESIGNATIONCIRCUIT

2-7-89LFEEDER – 3BAY – 7-TRANSFER BUSBAY – 6

2-8-89LFEEDER – 4BAY – 8

2-5-89TTRANSFORMER – 2BAY – 5-BUS COUPLERBAY – 4

2-3-89TTRANSFORMER – 1BAY – 32-2-89LFEEDER – 2BAY – 22-1-89LFEEDER – 1BAY – 1

CIRCUITBAY NO

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. IN THIS EACH FEEDER / TRANSFORMER / REACTOR IS HAVING CT & LA/SA TOWARDS

CIRCUIT.2. NORMAL APTRANSCO PRACTICE BUS COUPLER HAVING TWO SIDES CT. BUT MOST OF

THE UTILITIES HAVING ONE SIDE CT. BUS COUPLER NOT HAVING LA, CVT & WT/LT.3. TRANSFER BUS COUPLER HAVING ONE CT. TRANSFER BUS COUPLER NOT HAVING LA,

CVT & WT/LT.4. IN THIS EACH FEEDER IS HAVING CVT & WT/LT TOWARDS CIRCUIT.

2 – 8SA 2 – 7SA 2 – 6SA 2 – 5SA

2 – 4SA

2 – 3SA 2 – 2SA 2 – 1SA LA/SA

2 - 8CVT2 - 8CVT

--

-

-2 - 2CVT2 - 1CVT

CVT

2 – 8CT2 – 7CT2 – 6CT2 – 5CT

2 – 4 A/B CT

2 – 3CT2 – 2CT2 – 1CT

CTISOLATORS DESIGNATION

WT/LT

2 – 8LTFEEDER – 3BAY – 7-TRANSFER BUSBAY – 6

2 – 8LTFEEDER – 4BAY – 8

-TRANSFORMER – 2BAY – 5

-BUS COUPLERBAY – 4

-TRANSFORMER – 1BAY – 32 – 2LTFEEDER – 2BAY – 22 – 1LTFEEDER – 1BAY – 1

CIRCUITBAY NO

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. NORMALLY EACH FEEDER / TRANSFORMER / REACTOR IS TO BE CONNECTED TO EITHER

BUS-1 OR BUS-2, NOT BOTH.2. THE CONCEPT BEHIND IS WHEN EITHER OF THE BUS BAR PROTECTION OPERATES

ATLEAST 50% CIRCUITS WILL BE IN SERVICE. 3. FOR MAINTANENCE POINT OF VIEW IT IS HAPPY THAT ALL CIRCUITS KEPT ON ONE BUS

AND ANOTHER BUS CAN BE TAKEN IN TO MAINTANENCE.4. NORMALLY BUS-1 OR BUS-2 SELECTION IS TO BE DONE BEFORE CHARGING CIRCUIT.5. APTRANSCO STANDARD PRACTICE, IN CASE OF DOUBLE CIRCUIT, ONE CIRCUIT ON BUS-

1 AND CIRCUIT -2 ON BUS-2.6. FOR EXAMPLE VEMAGIRI-1 & 2 FEEDERS ARE AVAILABLE, VEMAGIRI -1CONNECTED ON

BUS-1 AND VEMAGIRI-2 CONNECTED ON BUS-2.7. IN CASE OF TRANSFORMER ICT-1 CONNECTED ON BUS-1 AND ICT-2 CONNECTED ON

BUS-2.8. THE BUS COUPLER BREAKER IS ALWAYS IN SERVICE. THE BUS-1 & 2 ISOLATORS BOTH

ARE CLOSSED POSITION.9. DURING SERVICE, CHANGE OVER BUS IS NOT A PRACTICE, HOWEVER THIS IS POSSIBLE

WHEN BUS COUPLER IS CLOSSED CONDITION ONLY. PLEASE REFER THE INTERLOCK CIRCUIT OF ANY FEEDER.

10. DURING SERVICE THE CHANGING OF BUS PROCEDURE IS AS FOLLOWS: IF THE CIRCUIT IS CONNECTED ON BUS-1, CLOSE BUS-2 ISO AND OPEN BUS-1 ISO. SIMILARLY FOR BUS-2 TO BUS-1 CHANGE OVER. DONOT PRACTICE REGULARLY. THIS IS PURELY FOR EMERGENCY AND WHEN BOTH ISOLATORS & CB OF BUS COUPLER IS CLOSSEDCONDITION ONLY.

11. THE ISOLATOR SELECTION IS GOING TO BUSBAR PROTECTION. i.e. IF BUS-1 ISO CLOSES CT IS CONNECTED TO BUSBAR-1 PROTECTION OR BUS-2 ISO CLOSES CT IS CONNECTED TO BUSBAR-2 PROTECTION.

12. DURING BUS BAR PROTECTION OPERATES, THE BAYS CONNECTED TO THAT BUS AND BUSCOUPLER CBs ARE OPENED. THIS EXPLAINED IN BUSBAR PROTECTION IN NEXT SLIDES.

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM1. NORMALLY TRANSFER BUS COUPLER CB & ISOs ARE ALWAYS IN OPEN CONDITION.2. WHEN ANY OF THE CB TROUBLE COMES THAT WILL BE TRANSFERED TO AUXILIARY BUS

AND THAT CIRCUIT IS FED FROM AUX BUS.3. THE OPERATION OF TRANSFER BUS WILL BE EXPLAINED IN NEXT SLIDES.4. FROM THE SAMPLE LAYOUT WE ARE PRESUMED THAT FEEDER-1, ICT-1 & FEEDER-3 ARE

CONNECTED ON BUS-1 AND FEEDER-2, ICT-2 & FEEDER-4 ARE CONNECTED ON BUS-2.5. BUS COUPLER CB & ISOLATORS ARE IN SERVICE.6. DURING THIS CHANGE OVER TO TRANSFER BUS, THE TRIPPING CIRCUITS ARE

TRANSFERRED TO TRANSFER BUS COUPLER CB.7. DURING THE CIRCUIT IS CONNECTED ON TRANSFER BUS COUPLER, IF FAULT OCCURS

ON CIRCUIT, THE PROTECTIVE RELAYS WILL GIVE TRIP SIGNAL TO CONCERNED CB AND TRANSFER BUS CB.

8. THIS CAN BE AVOIDED BY USING SOME MORE LOGIC.9. THE TBC CT ONE CORE IS CONNECTED TO SELECTION OF BUSBAR PROTECTION EITHER

BUS-1 & BUS-2 BASED ON ISOLATOR SELECTION.10. ANOTHER CORE IS CONNECTED TO BUS-3 BUSBAR PROTECTION.11. THIS IS EXPLAINED IN BUS BAR PROTECTION PRESENTATION.12. IN TRANSFER BUS PANEL, AUTO RECLOSURE RELAY IS AVAILABLE. THIS IS USEFUL

WHEN ANY FEEDER IS CONNECTED TO TBC, THEN IT IS USEFUL.13. IN TRANSFER BUS PANEL, TBC LBB RELAY IS ALSO AVAILABLE. 14. DURING THE OPERATION OF TRANSFERING THE CIRCUIT TO THE TBC, THE COMPLETE

SEQUENCE IS TO BE FOLLOWED. ANY THING WRONG, THEN ALARM WILL COME. THE OPERATION COMPLETES PERFECTLY THE ALARM WILL DISAPPEAR.

15. NORMAL CONVENTIONAL SYSTEM WE ARE PROVIDING TTS SWITCH. THIS IS TRIP TRANSFER SWITCH. IN NORMAL MODE TRIPING IS DONE FOR PARTICULAR CIRCUIT BREAKER, IF IT IS TRANSFER MODE THE TRIP CIRCUIT IS PARALLED AND EXTENDED TO TBC CIRCUIT BREAKER BAY.

16. IN AUTOMATION SYSTEM, THE LATCH RELAY MAY PROVIDE, FOR THIS OPERATION AND THAT CAN BE OPERATED FROM BCU/ REMOTE.

DOUBLE MAIN BUS & TRANSFER BUS SYSTEMNORMALLY FEEDER-1 IS CONNECTED BUS-1 & Feeder Protections are to be kept on Line CVTTHE SEQUENCE OF OPERATION STARTS AS FOLLOWS:1. PUT ALL PROTECTIONS ON LINE CVT.2. CLOSE TBC BAY BUS-1 ISOLATOR.3. CLOSE TBC BAY BUS-3 ISOLATOR.4. CLOSE FEEDER-1, BAY-3 ISOLATOR.5. SO THE TBC CB BOTH SIDES HAVING VOLTAGE.6. PUT TTS IN TRANSFER MODE OF FEEDER-1 PANEL.7. CLOSE THE TBC CB. 8. THEN, THE FEEDER-1 IS PARALLED WITH TBC CB AND FEEDING TWO PARALLEL PATHS.9. PATH1:FEEDER-1 CIRCUIT : FEEDER-1 BUS-1 ISO, FEEDER-1 CB, FEEDER-1 LINE ISO TO

FEEDER-1.10. PATH2:TBC CIRCUIT : TBC BUS-1 ISO, TBC CB, TBC BUS-3 ISO AND FEEDER-1 BUS-3 ISO

TO FEEDER-1.11. THEN OPEN FEEDER-1 CB.12. NOW THE FEEDER-1 IS FEEDING FROM TBC CB.13. OPEN THE FEEDER ISOLATORS i.e. BUS-1 ISO, LINE ISO. NOT BUS-3 ISO.14. AFTER MAINTANENCE WORK IS OVER, THE REVERSE PROCEDURE MAY BE FOLLOWED.TAKING TO NORMAL SYSTEM.1. CLOSE FEEDER-1 BUS-1 ISOLATOR.2. CLOSE FEEDER-1 LINE ISOLATOR.3. PUT TTS IN NORMAL MODE.4. CLOSE FEEDER-1 CIRCUIT BREAKER.5. OPEN TBC CB.6. OPEN TBC BAY BUS-1 ISOLATOR.7. OPEN TBC BAY BUS-3 ISOLATOR.8. OPEN FEEDER-1 BUS-3 ISOLATOR.

CHANGING OVER OPERATION OF FEEDER-1 TO TBC CIRCUIT & TO NORMAL


NORMALLY ICT-2 IS CONNECTED BUS-2.THE SEQUENCE OF OPERATION STARTS AS FOLLOWS:1. CLOSE TBC BAY BUS-2 ISOLATOR.2. CLOSE TBC BAY BUS-3 ISOLATOR.3. CLOSE ICT-2 BAY-3 ISOLATOR.4. SO THE TBC CB BOTH SIDES HAVING VOLTAGE.5. PUT TTS IN TRANSFER MODE IN ICT-2 PANEL.6. CLOSE THE TBC CB. 7. THEN, THE ICT-2 IS PARALLED WITH TBC AND FEEDING TWO PARALLEL PATHS.8. PATH1:ICT-2 CIRCUIT : ICT-2 BUS-2 ISO, ICT-2 CB, ICT-2 TRANSFORMER ISO TO ICT-2.9. PATH2:TBC CIRCUIT : TBC BUS-2 ISO, TBC CB, TBC BUS-3 ISO AND ICT-2 BUS-3 ISO TO

ICT-2.10. THEN OPEN ICT-2 CB.11. NOW THE ICT-2 IS FEEDING FROM TBC CB.12. OPEN THE ICT-2 ISOLATORS i.e. BUS-2 ISO, TRANSFORMER ISO. NOT BUS-3 ISO.13. AFTER MAINTANENCE WORK IS OVER, THE REVERSE PROCEDURE MAY BE FOLLOWED.TAKING TO NORMAL SYSTEM.1. CLOSE ICT-2 BUS-2 ISOLATOR.2. CLOSE ICT-2 TRANSFORMER ISOLATOR.3. PUT TTS IN NORMAL MODE.4. CLOSE ICT-2 CIRCUIT BREAKER.5. OPEN TBC CB.6. OPEN TBC BAY BUS-2 ISOLATOR.7. OPEN TBC BAY BUS-3 ISOLATOR.8. OPEN ICT-2 BUS-3 ISOLATOR.

CHANGING OVER OPERATION OF ICT-2 TO TBC CIRCUIT & TO NORMAL

DOUBLE MAIN BUS & TRANSFER BUS SYSTEMTHIS CONTAINS 1. INDIVIDUAL BAYS LIKE FEEDER/LINE, TRANSFORMER, REACTOR.2. BUS COUPLER BAY.3. TRANSFER BUS COUPLER BAY.

1. EACH FEEDER/LINE BAY CONTAINSA. LINE CONTROL PANELB. CB RELAY PANELC. LINE PROTECTION PANELD. LINE REACTOR PROTECTION PANEL2. EACH TRANSFORMER/ICT BAY

CONTAINSA. ICT HV CONTROL PANELB. HV CB RELAY PANELC. ICT PROTECTION PANEL.D. LV CB RELAY PANEL.E. ICT LV CONTROL PANEL3. EACH BUS REACTOR BAY CONTAINSA. REACTOR CONTROL PANELB. CB RELAY PANELC. REACTOR PROTECTION PANEL.

1. ENTIRE SUBSTATION CONTAINSA. BUSBAR PROTECTION PANELB. COMMON ANNUNCIATION/CONTROL

PANEL2. BUS COUPLER BAY CONTAINSA. BUS COUPLER CONTROL PANELB. BUS COUPLER RELAY & PROTECTION

PANEL3. BUS SECTIONALISER BAY CONTAINSA. BUS COUPLER CONTROL PANELB. BUS COUPLER RELAY & PROTECTION

PANEL4. TRANSFER BUS COUPLER BAY

CONTAINSA. TRANSFER BUS COUPLER CONTROL

PANELB. TRANSFER BUS COUPLER RELAY &

PROTECTION PANEL

THIS CONTAINS

BUSBAR PROTECTION PANEL

2 NoTransfer Bus Coupler Isolators Contact multiplication10

2 NoBus Earth Switches Contact Multiplier9

3 NoAuxiliary Relays to Close Bus Isolators of Particular Bus from BCU.8

Set

3-Ph High Speed Master Trip Relays with Electrical Reset through BCU for 96BB/50Z including Supervision. are at respective CB Relay Panels.

7

3 No

Bay Control Units for BUS-1, BUS-2 & Transfer Bus equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

6

2 NoDC-1 & DC-2 Supply Monitoring /Supervision relays for Gr-A & Gr-B 5

3 NoSelector Switch Bus IN / OUT for each Bus 4

--

Numerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection)Inbuilt function of Bus Bar Protection

3

setIncase of Distributed Architecture Bay/ Peripheral units are at respective CB Relay Panels.

2

1 No

3 Zone Numerical Bus Bar Protection Relay for Double Bus and Transfer Bus System of Either Distributed Architecture or Centralised Architecture with test plug.

1

QTYDESCRIPTIONS.NO

BCU3

BUSBARCENTRAL UNIT

2 RBB

DC-1

DC-2

BCU1 BCU2

89B

B1

AE

CM

R

89B

B2

AE

CM

R BusBarAux

relays

DISTRIBUTED ARCHITECTURE

BCU3

BUSBAR-1RELAY

2 RBB

DC-1

DC-2

BCU1 BCU2

89B

B1

AE

CM

R

89B

B2

AE

CM

R BusBarAux

relays

CENTRALISED ARCHITECTURE

BUSBAR-2RELAY

TRANSFER BUSRELAY

BUS COUPLER PANEL

1 NoEmergency Circuit Breaker TNC Switch or Push Button for CB Open & Close.

9

SetAuxiliary Relays to Close Circuit Breaker & Isolators of Particular Bay from BCU.

8

1 NoIDMT Numerical Non Directional O/C & E/F Relay 7

3 No

3-Ph High Speed Master Trip Relays with Electrical Reset through BCU for 86Gr-A, 86Gr-B & 96BB/50Z including Supervision.

6


6 NoTrip Coil Supervision Relays. 4

SetFlag relays two element type for Circuit Breaker Troubles 3

Set

Numerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection). (Bus Coupler Having Both Sides CTs.) (part of Busbar)

2

1 No

Bay Control Units for BC CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NO

BC BCU

2RBC

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

CB PB

LBB/ BU50Z

50/51 A,BC,N

96 50Z

AUTOMATION PANEL2RBC

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

LBB/ BU50Z

50/51 A,BC,N

96 50Z

CONVENTIONAL PANEL

CB ContactMultiplier

Relay

BUS SECTIONALISER PANEL

1 NoEmergency Circuit Breaker TNC Switch or Push Button for CB Open & Close.

9

SetAuxiliary Relays to Close Circuit Breaker & Isolators of Particular Bay from BCU.

8

1 NoIDMT Numerical Non Directional O/C & E/F Relay 7

3 No


6



SetFlag relays two element type for Circuit Breaker Troubles 3

Set

Numerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection). (Bus Coupler Having Both Sides CTs.) (part of Busbar)

2

1 No

Bay Control Units for BC CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NO

BC BCU

2RBS

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

CB PB

LBB/ BU50Z

50/51 A,BC,N

96 50Z

AUTOMATION PANEL2RBS

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

LBB/ BU50Z

50/51 A,BC,N

96 50Z

CONVENTIONAL PANEL

CB ContactMultiplier

Relay

TRANSFER BUS COUPLER PANEL

12 NoHigh Speed Single Phase Trip Relays with self resetting & Flag indication. 7

1 NoNumerical Auto Re-closure Relay Scheme Complete Scheme with Check Synchronizing and Dead Line charging.

3

1 NoEmergency Circuit Breaker TNC Switch or Push Button for CB Open & Close. 10

SetAuxiliary Relays to Close Circuit Breaker & Isolators of Particular Bay from BCU. 9

3 No


8



SetFlag relays two element type for Circuit Breaker Troubles for Alarms/ Event Logger / Disturbance Recorder.

4

1 NoNumerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection). (part of Busbar)

2

1 No

Bay Control Units for TBC CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NO

TBC BCU

2RTBC

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

186R1,Y1,B1R2,Y2,B2

DC

-1

86 GR-B

286R1,Y1,B1R2,Y2,B2 D

C-2

CB PB

96 50Z

A/R+SC79+25

ClosingAux

relays

AUTOMATION PANEL2RTBC

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

186R1,Y1,B1R2,Y2,B2

DC

-1

86 GR-B

286R1,Y1,B1R2,Y2,B2 D

C-2

96 50Z

A/R+SC79+25

CBMultiplyRelay

CONVENTIONAL PANEL

LINE CB RELAY PANEL

79 + 25(AUTO RECLOSURE + CHECK SYNC RELAY)

50 Z(LBB / BFR)

2RLA

CB TROUBLE ALARAM AND TRIP RELAYS

TSRTC-1

TSRTC-1I

DCI & II

86 GR -A1-PH TRIPRELAYS -6FOR 21L1

86 GR -B1-PH TRIPRELAYS -6FOR 21L2

BREAKERMULTIPLICATION RELAY

UNDER VOLTAGE

RELAY

D/T CH-1 RECEIVERELAYS


BAY1 BCU

2RLA

A/R+SC79+25

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

186R1,Y1,B1R2,Y2,B2

DC

-1

86 GR-B

286R1,Y1,B1R2,Y2,B2 D

C-2

CB PB

9650ZD/T CH-1 RECEIVERELAYS


CB, ISOCLSOINGAUX RLYS


SETUnder Voltage Relay for Line Isolator Earth Switch Interlock circuit. 12

1 No3-Ph Energy Meter for Both Export & Import with Test Terminal Blockwith RS232/485 with Modbus/ DNP 3.0 Protocol

13

SETAuxiliary Relays to Close Circuit Breaker & Isolators of Particular Bay from BCU. 10

2 NoHigh Speed Auxiliary trip relays with flags and self resetting for Direct Trip-1 & 2 Receive.

9

12 NoHigh Speed Single Phase Trip Relays with self resetting & Flag indication. 8

3 No3-Ph High Speed Master Trip Relays with Electrical Reset through BCU for 86Gr-A, 86Gr-B & 96BB/50Z including Supervision.

7



SETFlag relays two element type for Circuit Breaker Troubles for Alarms/ Event Logger / Disturbance Recorder.

4

1 NoNumerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection) 3

1 NoNumerical Auto Re-closure Relay Scheme Complete Scheme with Check Synchronizing and Dead Line charging.

2

1 NoBay Control Units for Line Main CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NOCONVENTIONAL PANEL AUTOMATION PANEL

ICT HV or LV CB RELAY PANEL


SetUnder Voltage Relay for Line Isolator Earth Switch Interlock circuit. 10

1 No

3-Ph Energy Meter for Both Export & Import with Test Terminal Block with RS232/485 with Modbus/ DNP 3.0 Protocol

11


4 NoHigh Speed Inter trip relays and self resetting7

3 No


6




3

1 NoNumerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection) (Part of Bus Bar Protection)

2

1 No

Bay Control Units for ICT Main CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NOCONVENTIONAL PANEL

BAY1 BCU

2RTRA

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

CB PB

9650Z


AUTOMATION PANEL

INTER TRIPRELAYS

50 Z(LBB / BFR)

2RTRA


TSRTC-1

TSRTC-1I

DCI & II

86 GR -A 86 GR -B


INTERTRIP

RELAYS

INTER TRIP

RELAYS

9650Z

CONVENTIONAL PANEL

REACTOR CB RELAY PANELCONVENTIONAL PANEL

BAY1 BCU

2RBRA

LBB/ BU50Z

CB TROUBLES& ALARMS

TRIP COIL1 & 2

HEALTHYLEDS

86 GR-A

DC

-1

86 GR-B D

C-2

CB PB

9650Z


AUTOMATION PANEL


SetUnder Voltage Relay for Line Isolator Earth Switch Interlock circuit. 9


3 No


6




3

1 NoNumerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection) (Part of Bus Bar Protection)

2

1 No

Bay Control Units for Bus Reactor Main CB Bay Equipment Control, Operation, Monitoring, Synchronisation & Interlocks with Mimic.

1

QTYDESCRIPTIONS.NO

50 Z(LBB / BFR)

2RBRA


TSRTC-1

TSRTC-1I

DCI & II

86 GR -A 86 GR -B


9650Z

CONVENTIONAL PANEL

CONVENTIONAL CONTROL PANELS(THESE ARE REPLACED BY BCU’s IN AUTOMATION)

LINE + REACTOR PROTECTION PANELLINE PROTECTION PANEL

2 NoCarrier Selector Switches for Main-1 &Main-2 for Auto reclosure and protection6


2 NoVoltage Selector Switch for BUS PT or LINE CVT for Main-1 & Main-2. 4

2 NoVoltage Selection Relays for BUS-1 & BUS-2 based on isolator selection 3

1 NoMAIN-2(21L2): Line Distance Protection2

1 NoMAIN-1(21L1): Line Distance Protection1

QTYDESCRIPTIONS.NO

2RLB

21L1

21L2

75A75B

2RLRC

87R

64R

75A,B

Reactor TroubleAlarms & Trips

21R

2 NoVoltage Selection Relays for BUS-1 & BUS-2 based on isolator selection6

LINE REACTOR PROTECTION PANEL


setReactor Trouble Alarms & Trips. 4

1 No64R: Reactor REF Protection Scheme 3

1 NoMAIN-2(21R): Reactor Backup impedance Protection Scheme2

1 NoMAIN-1(87R): Reactor Differential Protection Scheme1

QTYDESCRIPTIONS.NO

ICT + REACTOR PROTECTION PANEL

2 NoDirectional O/C + E/F Relays for HV & IV6

ICT PROTECTION PANEL

2 NoOver Flux Relays for HV & IV7


SetTransformer Troubles Alarms & Trips4

2 NoVoltage Selection Relays for BUS-1 & BUS-2 based on isolator selection 3

1 NoMAIN-2(87T2): ICT DifferentialProtection (HZ)2

1 NoMAIN-1(87T1): ICT Differential Protection (LZ)1

QTYDESCRIPTIONS.NO

2RBRB

87R

64R

75A,B

Reactor TroubleAlarms & Trips

21R

2 NoVoltage Selection Relays for BUS-1 & BUS-2 based on isolator selection6

BUS REACTOR PROTECTION PANEL


setReactor Trouble Alarms & Trips. 4

1 No64R: Reactor REF Protection Scheme 3

1 NoMAIN-2(21R): Reactor Backup impedance Protection Scheme2

1 NoMAIN-1(87R): Reactor Differential Protection Scheme1

QTYDESCRIPTIONS.NO

2RTRB

87T1

87T2

75A,B

Transformer TroubleAlarms & Trips

67HV 67IV

99HV 99IV

50O/L 50STUB

CBIP Guidelines on ProtectionGENERAL

Some broad guidelines for Engineering of Protection System are given below and could be refined if felt necessary by the Utility according to its specific needs and practices.

Wherever two sets of DC sources are available, to obtain redundancy and to be able to take protection out for maintenance, while equipment.

in service, the relays are electrically and physically segregated into two groups.

Interconnection between these two groups shall not generally be attempted.

Segregation of protections and trip circuits in two groups may be considered by giving DC supplies through separate fuses.

CBIP Guidelines on ProtectionGR-A & GR-B TRIPPINGS

For 400kV stations there shall be two separate Battery Systems available for Protection, Control & Tripping/ Closing operations. To obtain Redundancy and to be able to take Protection out for Maintenance, while equipment is in service, the Relays are Electrically and Physically segregated in to Two groups. Grouping is done to the extent possible in such a way that each group can independently carryout Protective functions with near equal redundancy. Inter connection of these two groups shall not be generally be attempted.Distribution of DC supply shall be done bay wise to feed the following1. Protection2. CB control3. Isolator / earth switch control4. Annunciation / indication


a) Protection Function:For each group of protection, separate DC sources are recommended.Example: Group-1: 21L1, 87T1, 67HV, 87R, 87BB1

Group-2: 21L2, 87T2, 67LV, 21R, 87BB2

b) CB FunctionsTrip coil 1 & 2 shall be fed from separate sources. Closing coil can be from either of these two sources.

c) Isolator / Earth switchThese associated with any one circuit shall be fed from one of the two DC sources.

In the case of One and half (1 & ½) CB arrangement, the Isolator / Earth switch associated with the tie CB can be fed from either source 1 or 2.


d) Annunciation & IndicationFor each bay, these functions can be fed from either one of the two sources. Each function shall be fed however through separate feeds.

e) Monitoring FunctionsThese shall be grouped in 3 groups

(i) Disturbance Recorders

(ii) Fault Locators

(iii) Event Loggers

All the three groups shall be fed through separate feeds from either of the two sources.Now days Numerical IEDs / Protective Relays are Having above functions are offered as inbuilt. Most of the Utilities are accepting this.

CBIP Guidelines on ProtectionCabling

It is recommended that:

(i) Separate cables are used for AC & DC circuit.

(ii) Separate cables are used for DC 1 & DC 2 circuits.

(iii) For different cores of CT & CVT separate cables shall be used.

GROUP-A & GROUP-B TRIPPINGSLINE

PROTECTIONTRANSFORMER

PROTECTIONREACTOR

PROTECTION

GROUP-AMAIN-1 PROTECTION (21L1)M1 BUILT IN FUNCTIONSTEED-1 PROTECTION (87 TEED-1)OVER VOLTAGE STAGE-1 PROT (59-1)DIRECT TRIP CHANNEL-1 RECEIVED

GROUP-BMAIN-2 PROTCTION (21L2)M2 BUILT IN FUNCTIONSTEED-2 PROTECTION (87 TEED-2)OVER VOLTAGE STAGE-2 PROT (59-2)LBB/BFR RELAY (50Z)DIRECT TRIP CHANNEL-2 RECEIVED

GROUP-AT/F DIFFERENTIAL RELAY (87T1)T/F B/U IMP RELAY (21T)T/F HV BACKUP RELAY (67HV)T/F HV OVERFLUX RELAY (99HV)TERITIARY DELTA WNDG NDR PROT OIL TEMP HIGH TRIPPRESURE RELIEF TRIPGROUP-BT/F HIGH Z DIFF RELAY (87T2)T/F NEUTRAL CURRENT RLY (51 NCT)T/F LV BACKUP RELAY (67LV)T/F LV OVERFLUX RELAY (99 LV)OVER LOAD PROT (ALARM ONLY)BUCHHOLZ TRIPOLTC BUCHHOLZ TRIPWINDING TEMP HIGH TRIPLOW/ HIGH OIL LEVEL TRIP

GROUP-AREACTOR DIFFERENTIAL RELAY (87R)REACTOR BACKUP RELAY (21 R)OIL TEMP HIGH TRIPPRESURE RELIEF TRIP

GROUP-BREACTOR REF RELAY (64R)BUCHHOLZ TRIPWINDING TEMP HIGH TRIPLOW/ HIGH OIL LEVEL TRIPFIRE PROTECTION TRIP

PRINCIPLE OF Gr-A & Gr-B SEPERATION

CT

CABLE

CABLE

PT

CVT

PT

BUS-1

BUS-2

LINE

CABLE

CABLE

CABLE

CABLE

CABLE

CABLE

BUS-1ISOLATORSELCTION

BUS-2ISOLATORSELCTION

BUS / LINEPT / CVT

SELCTION

CABLE

CABLE

DC SOURCE-1

DC SOURCE-2

ABB Network Partner AG

CE

COM581

CABLE

DC -1/2SELCTION

MAIN-1PROT

MAIN-2PROT

96 BB

86 Gr-A

86 Gr-B

BUS BAR PROT

TRIPCOIL-1

TRIPCOIL-2

ABB Network Partner AG

CE

COM581

LINE PROTECTIONS21L1 21L2

TRANSFORMER PROTECTIONS87T1 87T2

CIRCUIT BREAKERRELYS OF TRANSFER

BUS COUPLER

NORMAL

TRANSFER

GROUP-ATRIP UNIT

86 Gr-A

GROUP-BTRIP UNIT

86 Gr-B

GROUP-ATRIP UNIT

86 Gr-A

GROUP-BTRIP UNIT

86 Gr-B

GROUP-ATRIP UNIT

86 Gr-A

GROUP-BTRIP UNIT

86 Gr-B

A/R RELAY(79+25)

A/R RELAY(79+25)

A

B

A

B

A

B

AUTO RECLSOING FUNCTIONAUTO RECLOSING CIRCUITS:Arrangement of Relays

When Line is Transferred to Transfer Bus, Auto Reclosing Facility for This CB can be extended in Two Ways

* CB Oriented1. Individual Auto reclosure and Synchro-check relay for each CB . Hence co-

operation between CB’s and Synchro-check relay etc., is straight forward.

2. Interconnection between Line relays and reclosure relays complicated.

* LINE Oriented

1. Interconnection between Line relays and reclosure relays Simpler.

2. Connections to CB Oriented equipments complicated.

Note: CB Oriented Arrangement is preferred.

MAIN-1 PROTECTION CARRIER INTER TRIPPING

LINE 21L1CR

CS

-VECARRIER RECEIVE

CARRIER SEND

ALARM

IN

AB

BN

SD 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

AB

BN

SD 5

0 G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

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

+VE -VE

MAIN-2 PROTECTION CARRIER INTER TRIPPING

LINE 21L2CR

CS

-VECARRIER RECEIVE

CARRIER SEND

ALARM

IN

AB

BN

SD 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

AB

BN

SD 5

0 G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

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

+VE -VE

DIRECT TRANSFER TRIP – Gr-A

T N C

MAIN CB

M_CB CONTROL PANEL

87 BUSBAR TRIP

96 BUSBAR PROT PANEL

50 LBB/BFR FOR MAIN CB / RAICA

59L1 / OVER VOLTAGE STAGE-1


ABBNSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

PANEL-1

CONDITIONS FOR DIRECT TRIP1. TTS SWITCH IN NORMAL + MAIN CB REMOTE HAND TRIP GIVEN.2. TTS SWITCH IN TRANSFER + TBC CB REMOTE HAND TRIP GIVEN.3. 96 BUSBAR-1/2 OPERATED.4. TTS SWITCH IN NORMAL + MAIN CB 50 LBB/BFR OPERATED.5. TTS SWITCH IN TRANSFER + TBC CB 50 LBB/BFR OPERATED. 6. 59L1 OVER VOLTAGE STAGE-1 OPERATED.7. 59L2 OVER VOLTAGE STAGE-2 OPERATED.

N T

T N C

TBC CB

TBC_CB CONTROL PANELN T

N T

50 LBB/BFR FOR TBC CB / RAICAN T

DIRECT TRANSFER TRIP – Gr-B

T N C

MAIN CB

M_CB CONTROL PANEL

87 BUSBAR TRIP

96 BUSBAR PROT PANEL

50 LBB/BFR FOR MAIN CB / RAICA



ABBNSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

PANEL-1

CONDITIONS FOR DIRECT TRIP1. TTS SWITCH IN NORMAL + MAIN CB REMOTE HAND TRIP GIVEN.2. TTS SWITCH IN TRANSFER + TBC CB REMOTE HAND TRIP GIVEN.3. 96 BUSBAR-1/2 OPERATED.4. TTS SWITCH IN NORMAL + MAIN CB 50 LBB/BFR OPERATED.5. TTS SWITCH IN TRANSFER + TBC CB 50 LBB/BFR OPERATED. 6. 59L1 OVER VOLTAGE STAGE-1 OPERATED.7. 59L2 OVER VOLTAGE STAGE-2 OPERATED.

N T

T N C

TBC CB

TBC_CB CONTROL PANELN T

N T

50 LBB/BFR FOR TBC CB / RAICAN T

BASICS OF LBB/BFR 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.

BREAKER BACK-UP

BECAUSE 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 CHART

MAIN PROTECTIONOPERATED

YES

YES

TRIP MAIN

BREAKER

INITIATEBFR

WAIT FOR FAULT

CLEARENCEAND

FAULT CLEARED

YES

NO

RESETBREAKER FAILURE SCHEME

TRIPBACK-UP/Adjacent

BREAKERS

The Breaker Failure Protection (LBB/BFR) can operate single-stage/two-stage. When used as single-stage protection, the Bus trip command is given to the adjacent Circuit Breakers if the protected feeder Breaker fails. When used as two-stage protection, the first stage can be used to repeat the trip command to the relevant feeder Breaker, normally on a different trip coil, if the initial trip command from the feeder protection is not successful. The second stage will result in a Bus trip to the adjacent Breakers, if the command of the first stage is not successful.

RETRIP

LBB Operation & Output(MAIN BREAKER OF TRANSFER BUS SYSTEM)

INITIATION186 R186 Y186 B286 R286 Y286 B

86 GR-A86 GR-B

96 BB

+VE

TO D/T CH-1TO D/T CH-2TO ANNUNTO MAIN1 DRTO MAIN2 DRTO SERTO 86 GR-ATO 86 GR-BTO 96 BB

-VE50X

LBB / BFR

TIMER

+VEN T

In case of Feeder bay / Transformer Bay

+VEN T

In case of Transfer bay / Bus Coupler Bay for Transfer Bus / Bypass ISO System initiation to that LBB

TO BUSBAR

LBB Operation & Output(TBC BREAKER OF TRANSFER BUS SYSTEM)

INITIATION186 R186 Y186 B286 R286 Y286 B

86 GR-A86 GR-B

96 BB

+VE

TO D/T CH-1TO D/T CH-2TO ANNUNTO MAIN1 DRTO MAIN2 DRTO SERTO 86 GR-ATO 86 GR-BTO 96 BB

-VE50X

LBB / BFR

TIMER

+VEN T

In case of Feeder bay / Transformer Bay

+VEN T

In case of Main Circuit Breaker of Transfer Bus System initiation to that LBB

TO BUSBAR

NUMERICAL BUSBAR PROTECTION

In this two Models of BUSBAR Protections are available.1. Centralised Architecture.2. Distributed Architecture.The following are the advantages in this Numerical BUSBAR Protection

1. LBB, EFP and other Protections are inbuilt feature.2. Ratio Matching Transformers are not required. They can be

programmable.3. Isolator selection is required & selection relays are not required for zone

segregation. 4. One Unit is sufficient, for any no of Zones of BUSBAR Protection.5. In Distributed Architecture Communication between Bay Unit to Central

Unit is Fiber Optic connection. 6. Check Zone feature like Over-all Differential Protection & Over Current

Starter Protection is in built function.7. Current comparison, CT supervision, CT open circuit & CT Saturation

Detection is also inbuilt feature.8. Disturbance recorder and event recorders are inbuilt feature.9. BUSBAR Tripping Relays are Provided in each bay associated CB Relay

Panel and tripping through Bay Unit.10. These can be configured either High or Low impedance BUSBAR

Protection.

Traditionally Two Distinctive Architectures(CENTRALISED & DECENTRALISED)

• Fits better new installations• Perceived less reliable• Slower

52

DAU

52

DAU

52

DAU

CU

copper

fiber

Distributed Bus Protection

52 52 52

CU

copper

Centralized Bus Protection

• Fits better retrofit installations• Perceived more reliable• Potentially faster

DOUBLE BUS WITH TB- NUMERIC(1)

U U U U UU UU

BUS-1

BUS-2UUUU

UUUU

89A89B

ISOLATORSELECTION

89A89B89C

ISOLATORSELECTION

89A89B89C

ISOLATORSELECTION

89A89B89C

ISOLATORSELECTION

89A89B89C

ISOLATORSELECTION

AUX BUS

INDIVIDUAL RELAYS FOR EACH BUSBAR


U U U U UU UU

BUS-1

BUS-2UUUU

UUUU

BAYUNIT

89A

89B

89C

89A

89B

89C

BAYUNIT

89A

89B

89A

89B

89C

89A

89B

89C

BAYUNIT

BAYUNIT

BAYUNIT

BAYUNIT

BAYUNIT

BAYUNIT

AUX BUS

87BB DISTRIBUTED ARCHITECTURE


U U U U UU UU

BUS-1

BUS-2UUUU

UUUU

89A

89B

89C

89A

89B

89C

89A

89B

89A

89B

89C

89A

89B

89C

AUX BUS

87BB CENTRALISED ARCHITECTURE

transfer bus

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