Double Bus and Transfer Bus System

(1)

P. GOPALA KRISHNA

ADE/400KV/APTRANSCO

(2)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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.

(3)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

FEEDER1

BUS-2

BUS-1

FEEDER2

TRAN SFER B U S COUPLER

T/F-1

T/F-2

BUS COUP LE R

TRANSFER BUS

FEEDER3 FEEDER4

BAY1 BAY2

BAY3 BAY4 BAY5

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DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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 CB

FEEDER – 3

BAY – 7

2 – 6 – 52 CB

TRANSFER BUS

BAY – 6

2 – 8 – 52 CB

FEEDER – 4

BAY – 8

2 – 5 – 52 CB

TRANSFORMER – 2

BAY – 5

2 – 4 – 52 CB

BUS COUPLER

BAY – 4

2 – 3 – 52 CB

TRANSFORMER – 1

BAY – 3

2 – 2 – 52 CB

FEEDER – 2

BAY – 2

2 – 1 – 52 CB

FEEDER – 1

BAY – 1

CB DESIGNATION

CIRCUIT

BAY NO

(5)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

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.

(6)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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.

2-8-89B

2-7-89B

2-6-89B

2-5-89B

2-4-89B

2-3-89B

2-2-89B

2-1-89B

BUS-2

2-8-89C

2-7-89C

2-6-89C

2-5-89C

-2-3-89C

2-2-89C

2-1-89C

TR BUS

2-8-89A

2-7-89A

2-6-89A

2-5-89A

2-4-89A

2-3-89A

2-2-89A

2-1-89A

BUS-1

ISOLATORS DESIGNATION

CIRCUIT

2-7-89L

FEEDER – 3

BAY – 7

-TRANSFER BUS

BAY – 6

2-8-89L

FEEDER – 4

BAY – 8

2-5-89T

TRANSFORMER – 2

BAY – 5

-BUS COUPLER

BAY – 4

2-3-89T

TRANSFORMER – 1

BAY – 3

2-2-89L

FEEDER – 2

BAY – 2

2-1-89L

FEEDER – 1

BAY – 1

CIRCUIT

BAY NO

(7)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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 - 8CVT

-2 - -2CVT

2 - 1CVT

CVT

2 – 8CT

2 – 7CT

2 – 6CT

2 – 5CT

2 – 4

A/B CT

2 – 3CT

2 – 2CT

2 – 1CT

CT

ISOLATORS DESIGNATION

WT/LT

2 – 8LT

FEEDER – 3

BAY – 7

-TRANSFER BUS

BAY – 6

2 – 8LT

FEEDER – 4

BAY – 8

-TRANSFORMER – 2

BAY – 5

-BUS COUPLER

BAY – 4

-TRANSFORMER – 1

BAY – 3

2 – 2LT

FEEDER – 2

BAY – 2

2 – 1LT

FEEDER – 1

BAY – 1

CIRCUIT

BAY NO

(8)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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 CLOSSED CONDITION 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.

(9)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

1. 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.

(10)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

NORMALLY FEEDER-1 IS CONNECTED BUS-1 & Feeder Protections are to be kept on Line CVT

THE SEQUENCE OF OPERATION STARTS AS FOLLOWS

:

1. PUT ALL PROTECTIONS ON LINE CVT.

2. CLOSE TBC BAY BUS-1 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.

8. OPEN FEEDER-1 BUS-3 ISOLATOR.

(11)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

NORMALLY ICT-2 IS CONNECTED BUS-2.

THE SEQUENCE OF OPERATION STARTS AS FOLLOWS

:

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.

8. OPEN ICT-2 BUS-3 ISOLATOR.

(12)

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

THIS CONTAINS

1. INDIVIDUAL BAYS LIKE FEEDER/LINE, TRANSFORMER, REACTOR.

2. BUS COUPLER BAY.

3. TRANSFER BUS COUPLER BAY.

1. EACH FEEDER/LINE BAY CONTAINS

A. LINE CONTROL PANEL B. CB RELAY PANEL

C. LINE PROTECTION PANEL

D. LINE REACTOR PROTECTION PANEL

2. EACH TRANSFORMER/ICT BAY CONTAINS

A. ICT HV CONTROL PANEL B. HV CB RELAY PANEL

C. ICT PROTECTION PANEL. D. LV CB RELAY PANEL. E. ICT LV CONTROL PANEL

3. EACH BUS REACTOR BAY CONTAINS

A. REACTOR CONTROL PANEL B. CB RELAY PANEL

C. REACTOR PROTECTION PANEL.

1. ENTIRE SUBSTATION CONTAINS

A. BUSBAR PROTECTION PANEL

B. COMMON ANNUNCIATION/CONTROL PANEL

2. BUS COUPLER BAY CONTAINS

A. BUS COUPLER CONTROL PANEL

B. BUS COUPLER RELAY & PROTECTION PANEL

3. BUS SECTIONALISER BAY CONTAINS

A. BUS COUPLER CONTROL PANEL

B. BUS COUPLER RELAY & PROTECTION PANEL

4. TRANSFER BUS COUPLER BAY CONTAINS

A. TRANSFER BUS COUPLER CONTROL PANEL

B. TRANSFER BUS COUPLER RELAY & PROTECTION PANEL

(13)

BUSBAR PROTECTION PANEL

2 No Transfer Bus Coupler Isolators Contact

multiplication 10

2 No Bus Earth Switches Contact Multiplier

9

3 No

Auxiliary 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 No DC-1 & DC-2 Supply Monitoring

/Supervision relays for Gr-A & Gr-B 5

3 No Selector 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

set Incase 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 QTY DESCRIPTION S.NO BCU3 BUSBAR CENTRAL UNIT 2 RBB DC -1 DC -2 BCU1 BCU2 89BB1 _AE C M R 89BB2 _AE C M R Bus Bar Aux relays DISTRIBUTED ARCHITECTURE BCU3 BUSBAR-1 RELAY 2 RBB DC -1 DC -2 BCU1 BCU2 89BB1 _AE C M R 89BB2 _AE C M R Bus Bar Aux relays CENTRALISED ARCHITECTURE BUSBAR-2 RELAY TRANSFER BUS RELAY

(14)

BUS COUPLER PANEL

1 No Emergency Circuit Breaker TNC

Switch or Push Button for CB Open & Close.

9

Set Auxiliary Relays to Close Circuit

Breaker & Isolators of Particular Bay from BCU.

8

1 No IDMT 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 No Trip Coil Supervision Relays.

4

Set Flag 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 QTY DESCRIPTION S.NO BC BCU 2RBC LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 CB PB LBB/ BU 50Z 50/51 A,B C,N 96 50Z AUTOMATION PANEL 2RBC CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 LBB/ BU 50Z 50/51 A,B C,N 96 50Z CONVENTIONAL PANEL CB Contact Multiplier Relay

(15)

BUS SECTIONALISER PANEL

1 No Emergency Circuit Breaker TNC

Switch or Push Button for CB Open & Close.

9

Set Auxiliary Relays to Close Circuit

Breaker & Isolators of Particular Bay from BCU.

8

1 No IDMT Numerical Non Directional O/C

& E/F Relay 7

with Electrical Reset through BCU for 86Gr-A, 86Gr-B & 96BB/50Z

including Supervision. 6

4

Set Flag 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 QTY DESCRIPTION S.NO BC BCU 2RBS LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 CB PB LBB/ BU 50Z 50/51 A,B C,N 96 50Z AUTOMATION PANEL 2RBS CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 LBB/ BU 50Z 50/51 A,B C,N 96 50Z CONVENTIONAL PANEL CB Contact Multiplier Relay

(16)

TRANSFER BUS COUPLER PANEL

12 No

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

1 No Numerical Auto Re-closure Relay

Scheme Complete Scheme with Check Synchronizing and Dead Line charging. 3

1 No Emergency Circuit Breaker TNC Switch

or Push Button for CB Open & Close. 10

Set Auxiliary Relays to Close Circuit Breaker

& Isolators of Particular Bay from BCU. 9

with Electrical Reset through BCU for 86Gr-A, 86Gr-B & 96BB/50Z including Supervision.

8

5

Set Flag relays two element type for Circuit

Breaker Troubles for Alarms/ Event Logger / Disturbance Recorder. 4

1 No Numerical 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 QTY DESCRIPTION S.NO TBC BCU 2RTBC LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A 186 R1,Y1,B1 R2,Y2,B2 DC-1 86 GR-B 286 R1,Y1,B1 R2,Y2,B2 DC-2 CB PB 96 50Z A/R+SC 79+25 Closing Aux relays AUTOMATION PANEL 2RTBC LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A 186 R1,Y1,B1 R2,Y2,B2 DC-1 86 GR-B 286 R1,Y1,B1 R2,Y2,B2 DC-2 96 50Z A/R+SC 79+25 CB Multiply Relay CONVENTIONAL PANEL

(17)

LINE CB RELAY PANEL

79 + 25 (AUTO RECLOSURE +

CHECK SYNC RELAY) 50 Z

(LBB / BFR)

2RLA

CB TROUBLE ALARAM AND TRIP RELAYS

TSR TC-1 TSR TC-1I DC I & II 86 GR -A 1-PH TRIP RELAYS -6 FOR 21L1 86 GR -B 1-PH TRIP RELAYS -6 FOR 21L2 BREAKER MULTIPLICA TION RELAY UNDER VOLTAGE RELAY D/T CH-1 RECEIVE RELAYS D/T CH-2 RECEIVE RELAYS BAY1 BCU 2RLA A/R+SC 79+25 LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A 186 R1,Y1,B1 R2,Y2,B2 DC-1 86 GR-B 286 R1,Y1,B1 R2,Y2,B2 DC-2 CB PB 96 50Z D/T CH-1 RECEIVE RELAYS D/T CH-2 RECEIVE RELAYS CB, ISO CLSOING AUX RLYS 1 No

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

11

SET

Under Voltage Relay for Line Isolator Earth Switch Interlock circuit.

12

1 No

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

13

SET

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

10

2 No

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

9

12 No High Speed Single Phase Trip Relays with

self resetting & Flag indication.

8

3 No

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

7

2 No

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

6

6 No

Trip Coil Supervision Relays.

5

SET

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

4

1 No

Numerical Breaker Failure Relay.

(BFR/CBF/LBB/ Stuck Breaker Protection)

3

1 No

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

2

1 No

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

1

QTY DESCRIPTION

S.NO

(18)

ICT HV or LV CB RELAY PANEL

1 No

9

Set

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

SET

8

4 No

High Speed Inter trip relays and self resetting

7

3 No

6

2 No

5

6 No

4

Set

3

1 No

Numerical 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 QTY DESCRIPTION S.NO CONVENTIONAL PANEL BAY1 BCU 2RTRA LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 CB PB 96 50Z CB, ISO CLSOING AUX RLYS AUTOMATION PANEL INTER TRIP RELAYS 50 Z (LBB / BFR) 2RTRA CB TROUBLE ALARAM AND TRIP RELAYS

TSR TC-1 TSR TC-1I DC I & II 86 GR -A 86 GR -B BREAKER MULTIPLICA TION RELAY INTER TRIP RELAYS INTER TRIP RELAYS 96 50Z CONVENTIONAL PANEL

(19)

REACTOR CB RELAY PANEL

CONVENTIONAL PANEL BAY1 BCU 2RBRA LBB/ BU 50Z CB TROUBLES & ALARMS TRIP COIL 1 & 2 HEALTHY LEDS 86 GR-A DC-1 86 GR-B DC-2 CB PB 96 50Z CB, ISO CLSOING AUX RLYS AUTOMATION PANEL 1 No

8

Set

9

SET

7

3 No

6

2 No

5

6 No

4

Set

3

1 No

Numerical 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 QTY DESCRIPTION S.NO 50 Z (LBB / BFR) 2RBRA CB TROUBLE ALARAM AND TRIP RELAYS

TSR TC-1 TSR TC-1I DC I & II 86 GR -A 86 GR -B BREAKER MULTIPLICA TION RELAY 96 50Z CONVENTIONAL PANEL

(20)

CONVENTIONAL CONTROL PANELS

(21)

LINE + REACTOR PROTECTION PANEL

LINE PROTECTION PANEL

2 No

Carrier Selector Switches for Main-1 &Main-2 for Auto reclosure and protection

6

2 No

5

2 No

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

4

2 No

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

3

1 No MAIN-2(21L2): Line Distance Protection

2

1 No MAIN-1(21L1): Line Distance Protection

1 QTY DESCRIPTION S.NO 2RLB 21L1 21L2 75A 75B 2RLRC 87R 64R 75A,B Reactor Trouble Alarms & Trips

21R

2 No

6

LINE REACTOR PROTECTION PANEL

2 No

5

set

Reactor Trouble Alarms & Trips.

4

1 No 64R: Reactor REF Protection Scheme

3

1 No MAIN-2(21R): Reactor Backup impedance

Protection Scheme

2

1 No MAIN-1(87R): Reactor Differential Protection

Scheme

1

QTY DESCRIPTION

(22)

ICT + REACTOR PROTECTION PANEL

2 No

Directional O/C + E/F Relays for HV & IV

6

ICT PROTECTION PANEL

2 No

Over Flux Relays for HV & IV

7

2 No

5

Set

Transformer Troubles Alarms & Trips

4

2 No

3

1 No MAIN-2(87T2): ICT DifferentialProtection (HZ)

2

1 No MAIN-1(87T1): ICT Differential Protection (LZ)

1 QTY DESCRIPTION S.NO 2RBRB 87R 64R 75A,B Reactor Trouble Alarms & Trips

21R

2 No

6

BUS REACTOR PROTECTION PANEL

2 No

5

set

Reactor Trouble Alarms & Trips.

4

1 No 64R: Reactor REF Protection Scheme

3

1 No MAIN-2(21R): Reactor Backup impedance

Protection Scheme

2

1 No MAIN-1(87R): Reactor Differential Protection

Scheme 1 QTY DESCRIPTION S.NO 2RTRB 87T1 87T2 75A,B Transformer Trouble Alarms & Trips

67HV 67IV 99HV 99IV 50O/L 50STUB

(23)

(24)

CBIP Guidelines on Protection

GENERAL

¾ 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.

¾ Wherever two sets of DC sources are available, to

obtain redundancy and to be able to take protection

out for maintenance, while equipment.

¾ in service, the relays are electrically and physically

segregated into two groups.

¾ Interconnection between these two groups shall not

generally be attempted.

¾ Segregation of protections and trip circuits in two

groups may be considered by giving DC supplies

through separate fuses.

(25)

CBIP Guidelines on Protection

GR-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

following

1. Protection

2. CB control

3. Isolator / earth switch control

4. Annunciation / indication

(26)

CBIP Guidelines on Protection

GR-A & GR-B TRIPPINGS

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 Functions

Trip coil 1 & 2 shall be fed from separate sources.

Closing coil can be from either of these two sources.

c) Isolator / Earth switch

These 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.

(27)

CBIP Guidelines on Protection

GR-A & GR-B TRIPPINGS

d) Annunciation & Indication

For 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 Functions

These 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.

(28)

CBIP Guidelines on Protection

Cabling

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

(29)

GROUP-A & GROUP-B TRIPPINGS

LINE

PROTECTION

TRANSFORMER

PROTECTION

REACTOR

PROTECTION

GROUP-A

MAIN-1 PROTECTION (21L1)

M1 BUILT IN FUNCTIONS

TEED-1 PROTECTION (87 TEED-1)

OVER VOLTAGE STAGE-1 PROT (59-1)

DIRECT TRIP CHANNEL-1 RECEIVED

GROUP-B

MAIN-2 PROTCTION (21L2)

M2 BUILT IN FUNCTIONS

TEED-2 PROTECTION (87 TEED-2)

OVER VOLTAGE STAGE-2 PROT (59-2)

LBB/BFR RELAY (50Z)

DIRECT TRIP CHANNEL-2 RECEIVED

GROUP-A

T/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 TRIP

PRESURE RELIEF TRIP

GROUP-B

T/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 TRIP

OLTC BUCHHOLZ TRIP

WINDING TEMP HIGH TRIP

LOW/ HIGH OIL LEVEL TRIP

GROUP-A

REACTOR DIFFERENTIAL RELAY (87R)

REACTOR BACKUP RELAY (21 R)

OIL TEMP HIGH TRIP

PRESURE RELIEF TRIP

GROUP-B

REACTOR REF RELAY (64R)

BUCHHOLZ TRIP

WINDING TEMP HIGH TRIP

LOW/ HIGH OIL LEVEL TRIP

FIRE PROTECTION TRIP

(30)

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-1 ISOLATOR SELCTION BUS-2 ISOLATOR SELCTION BUS / LINE PT / CVT SELCTION CABLE CABLE DC SOURCE-1 DC SOURCE-2

ABB Network Partner AG

C E COM581 CABLE DC -1/2 SELCTION MAIN-1 PROT MAIN-2 PROT 96 BB 86 Gr-A 86 Gr-B BUS BAR PROT

TRIP COIL-1

TRIP COIL-2

(31)

ABB Network Partner AG C E COM581 LINE PROTECTIONS 21L1 21L2 TRANSFORMER PROTECTIONS 87T1 87T2 CIRCUIT BREAKER RELYS OF TRANSFER BUS COUPLER NORMAL TRANSFER GROUP-A TRIP UNIT 86 Gr-A GROUP-B TRIP UNIT 86 Gr-B GROUP-A TRIP UNIT 86 Gr-A GROUP-B TRIP UNIT 86 Gr-B GROUP-A TRIP UNIT 86 Gr-A GROUP-B TRIP UNIT 86 Gr-B A/R RELAY (79+25) A/R RELAY (79+25)

A

B

A

B

A

B

(32)

AUTO RECLSOING FUNCTION

AUTO 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 Oriented

1. 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.

(33)

MAIN-1 PROTECTION CARRIER INTER TRIPPING

LINE 21L1

CR CS -VE CARRIER RECEIVE CARRIER SEND ALARM IN

ABB

NSD 50

OUT PANEL-1 PANEL-2

G4AC V9LC 1

G4AC V9LC 2

G4AC V9LC 5

G4AC V9LC 6

G4AA V9LB 5

G4AA V9LB 6

ABB

NSD 50

G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

G4AC V9LC 13

THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIP

AND CONNECTED IN ANOTHER PANEL

(34)

MAIN-2 PROTECTION CARRIER INTER TRIPPING

LINE 21L2

CR CS -VE CARRIER RECEIVE CARRIER SEND ALARM IN

ABB

NSD 50

OUT PANEL-2 PANEL-1

G4AC V9LC 1

G4AC V9LC 2

G4AC V9LC 5

G4AC V9LC 6

G4AA V9LB 5

G4AA V9LB 6

ABB

NSD 50

G4AC V9LC 10

G4AC V9LC 14

G4AC V9LC 9

G4AC V9LC 13

THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIP

AND CONNECTED IN ANOTHER PANEL

(35)

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

ABB

NSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

PANEL-1

CONDITIONS FOR DIRECT TRIP

1. 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.

N T T N C TBC CB TBC_CB CONTROL PANEL N T N T 50 LBB/BFR FOR TBC CB / RAICA N T

(36)

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

ABB

NSD 50

DC +VE FROM PANEL

G4AD V9LC 2

DC –VE FROM PANEL

G4AD V9LC 1

PANEL-1

CONDITIONS FOR DIRECT TRIP

1. 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.

N T T N C TBC CB TBC_CB CONTROL PANEL N T N T 50 LBB/BFR FOR TBC CB / RAICA N T

(37)

BASICS OF LBB/BFR PROTECTION

LOCAL 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.

(38)

LBB/BFR FLOW CHART

MAIN PROTECTION OPERATED YES YES TRIP MAIN BREAKER INITIATE BFR WAIT FOR FAULT CLEARENCE AND FAULT CLEARED YES NO RESET BREAKER FAILURE SCHEME TRIP BACK-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.

(39)

LBB Operation & Output

(MAIN BREAKER OF TRANSFER BUS SYSTEM)

INITIATION 186 R 186 Y 186 B 286 R 286 Y 286 B 86 GR-A 86 GR-B 96 BB

+VE

TO D/T CH-1 TO D/T CH-2 TO ANNUN TO MAIN1 DR TO MAIN2 DR TO SER TO 86 GR-A TO 86 GR-B TO 96 BB

-VE

50X

LBB / BFR

TIMER

+VE

N T In case of Feeder bay / Transformer Bay

+VE

N T

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

(40)

LBB Operation & Output

(TBC BREAKER OF TRANSFER BUS SYSTEM)

INITIATION 186 R 186 Y 186 B 286 R 286 Y 286 B 86 GR-A 86 GR-B 96 BB

+VE

TO D/T CH-1 TO D/T CH-2 TO ANNUN TO MAIN1 DR TO MAIN2 DR TO SER TO 86 GR-A TO 86 GR-B TO 96 BB

-VE

50X

LBB / BFR

TIMER

+VE N T

In case of Feeder bay / Transformer Bay

+VE

N T

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

(41)

NUMERICAL BUSBAR PROTECTION

¾

In this two Models of BUSBAR Protections are available.

1. Centralised Architecture.

2. Distributed Architecture.

¾

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.

(42)

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

(43)

DOUBLE BUS WITH TB- NUMERIC(1)

UU

BUS-1

BUS-2

UU

89A 89B ISOLATOR SELECTION 89A 89B 89C ISOLATOR SELECTION 89A 89B 89C ISOLATOR SELECTION 89A 89B 89C ISOLATOR SELECTION 89A 89B 89C ISOLATOR SELECTION

AUX BUS

(44)

DOUBLE BUS WITH TB- NUMERIC(2)

UU

BUS-1

BUS-2

UU

BAY UNIT 89A 89B 89 C 89A 89B 89 C BAY UNIT 89A 89B 89A 89B 89 C 89A 89B 89 C BAY UNIT BAY UNIT BAY UNIT BAY UNIT BAY UNIT BAY UNIT