Double Bus and Transfer Bus System

P. GOPALA KRISHNA ADE/400KV/APTRANSCO

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM 1. 2. 3. 4. 5.

In This Two Main Buses Are Available. They Are Called Bus-1 & Bus-2. One More Bus Is Available. This is Not Main Bus. We Call As Transfer Bus Or Auxiliary Bus Or Temporary Bus. 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 T/F-1

T/F-2

BUS-2

BAY3 BAY1

BAY2

FEEDER1 FEEDER2

BAY4

TRANSFER BUS

BAY5

TRANSFER BUS COUPLER

BUS COUPLER

BUS-1

BAY6

BAY7

BAY8

FEEDER3 FEEDER4

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM 1. 2. 3. 4. 5. 6. 7. 8.

In this each Feeder / Transformer / Reactor is having one Circuit Breaker. One Circuit Breaker for Bus Coupler. One more Circuit Breaker for Transfer Bus Coupler. The details are as follows based on layout. CB designation is very specific. First number will show voltage level. For 765 KV - 7, 550KV-5, 400KV -4, 220KV-2, 132KV -1. Second number will show Bay number. 52 is ANSI code for CB. Some of the locations it is called Q0.

BAY NO

CIRCUIT

CB DESIGNATION

BAY – 1

FEEDER – 1

2 – 1 – 52 CB

BAY – 2

FEEDER – 2

2 – 2 – 52 CB

BAY – 3

TRANSFORMER – 1

2 – 3 – 52 CB

BAY – 4

BUS COUPLER

2 – 4 – 52 CB

BAY – 5

TRANSFORMER – 2

2 – 5 – 52 CB

BAY – 6

TRANSFER BUS

2 – 6 – 52 CB

BAY – 7

FEEDER – 3

2 – 7 – 52 CB

BAY – 8

FEEDER – 4

2 – 8 – 52 CB

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM

STANDARD PRACTICE 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.

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.

BAY NO

CIRCUIT

BAY – 1

ISOLATORS DESIGNATION BUS-1

BUS-2

TR BUS

CIRCUIT

FEEDER – 1

2-1-89A

2-1-89B

2-1-89C

2-1-89L

BAY – 2

FEEDER – 2

2-2-89A

2-2-89B

2-2-89C

2-2-89L

BAY – 3

TRANSFORMER – 1

2-3-89A

2-3-89B

2-3-89C

2-3-89T

BAY – 4

BUS COUPLER

2-4-89A

2-4-89B

-

-

BAY – 5

TRANSFORMER – 2

2-5-89A

2-5-89B

2-5-89C

2-5-89T

BAY – 6

TRANSFER BUS

2-6-89A

2-6-89B

2-6-89C

-

BAY – 7

FEEDER – 3

2-7-89A

2-7-89B

2-7-89C

2-7-89L

BAY – 8

FEEDER – 4

2-8-89A

2-8-89B

2-8-89C

2-8-89L

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.

BAY NO

CIRCUIT

BAY – 1

ISOLATORS DESIGNATION CT

LA/SA

CVT

WT/LT

FEEDER – 1

2 – 1CT

2 – 1SA

2 - 1CVT

2 – 1LT

BAY – 2

FEEDER – 2

2 – 2CT

2 – 2SA

2 - 2CVT

2 – 2LT

BAY – 3

TRANSFORMER – 1

2 – 3CT

2 – 3SA

-

-

BAY – 4

BUS COUPLER

2–4 A/B CT

2 – 4SA

-

-

BAY – 5

TRANSFORMER – 2

2 – 5CT

2 – 5SA

-

-

BAY – 6

TRANSFER BUS

2 – 6CT

2 – 6SA

-

-

BAY – 7

FEEDER – 3

2 – 7CT

2 – 7SA

2 - 8CVT

2 – 8LT

BAY – 8

FEEDER – 4

2 – 8CT

2 – 8SA

2 - 8CVT

2 – 8LT

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 BUS1 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.

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.

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM CHANGING OVER OPERATION OF FEEDER-1 TO TBC CIRCUIT & TO NORMAL 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. 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. 2. 3. 4. 5. 6. 7. 8.

CLOSE FEEDER-1 BUS-1 ISOLATOR. CLOSE FEEDER-1 LINE ISOLATOR. PUT TTS IN NORMAL MODE. CLOSE FEEDER-1 CIRCUIT BREAKER. OPEN TBC CB. OPEN TBC BAY BUS-1 ISOLATOR. OPEN TBC BAY BUS-3 ISOLATOR. OPEN FEEDER-1 BUS-3 ISOLATOR.

DOUBLE MAIN BUS & TRANSFER BUS SYSTEM CHANGING OVER OPERATION OF ICT-2 TO TBC CIRCUIT & TO NORMAL NORMALLY ICT-2 IS CONNECTED BUS-2. THE SEQUENCE OF OPERATION STARTS AS FOLLOWS: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13.

CLOSE TBC BAY BUS-2 ISOLATOR. CLOSE TBC BAY BUS-3 ISOLATOR. CLOSE ICT-2 BAY-3 ISOLATOR. SO THE TBC CB BOTH SIDES HAVING VOLTAGE. PUT TTS IN TRANSFER MODE IN ICT-2 PANEL. CLOSE THE TBC CB. THEN, THE ICT-2 IS PARALLED WITH TBC AND FEEDING TWO PARALLEL PATHS. PATH1:ICT-2 CIRCUIT : ICT-2 BUS-2 ISO, ICT-2 CB, ICT-2 TRANSFORMER ISO TO ICT-2. PATH2:TBC CIRCUIT : TBC BUS-2 ISO, TBC CB, TBC BUS-3 ISO AND ICT-2 BUS-3 ISO TO ICT-2. THEN OPEN ICT-2 CB. NOW THE ICT-2 IS FEEDING FROM TBC CB. OPEN THE ICT-2 ISOLATORS i.e. BUS-2 ISO, TRANSFORMER ISO. NOT BUS-3 ISO. AFTER MAINTANENCE WORK IS OVER, THE REVERSE PROCEDURE MAY BE FOLLOWED.

TAKING TO NORMAL SYSTEM. 1. 2. 3. 4. 5. 6. 7. 8.

CLOSE ICT-2 BUS-2 ISOLATOR. CLOSE ICT-2 TRANSFORMER ISOLATOR. PUT TTS IN NORMAL MODE. CLOSE ICT-2 CIRCUIT BREAKER. OPEN TBC CB. OPEN TBC BAY BUS-2 ISOLATOR. OPEN TBC BAY BUS-3 ISOLATOR. OPEN ICT-2 BUS-3 ISOLATOR.

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.

THIS CONTAINS 1. A. B. 2. A. B. 3. A. B. 4. A. B.

ENTIRE SUBSTATION CONTAINS BUSBAR PROTECTION PANEL COMMON ANNUNCIATION/CONTROL PANEL BUS COUPLER BAY CONTAINS BUS COUPLER CONTROL PANEL BUS COUPLER RELAY & PROTECTION PANEL BUS SECTIONALISER BAY CONTAINS BUS COUPLER CONTROL PANEL BUS COUPLER RELAY & PROTECTION PANEL TRANSFER BUS COUPLER BAY CONTAINS TRANSFER BUS COUPLER CONTROL PANEL TRANSFER BUS COUPLER RELAY & PROTECTION PANEL

1. A. B. C. D. 2. A. B. C. D. E. 3. A. B. C.

EACH FEEDER/LINE BAY CONTAINS LINE CONTROL PANEL CB RELAY PANEL LINE PROTECTION PANEL LINE REACTOR PROTECTION PANEL EACH TRANSFORMER/ICT BAY CONTAINS ICT HV CONTROL PANEL HV CB RELAY PANEL ICT PROTECTION PANEL. LV CB RELAY PANEL. ICT LV CONTROL PANEL EACH BUS REACTOR BAY CONTAINS REACTOR CONTROL PANEL CB RELAY PANEL REACTOR PROTECTION PANEL.

BUSBAR PROTECTION PANEL

BCU1

BUSBAR CENTRAL UNIT 89BB2 AE CMR

QTY

1

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 No

2

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

set

3

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

--

4

Selector Switch Bus IN / OUT for each Bus

3 No

5

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

2 No

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

3 No

7

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

Set

8

Auxiliary Relays to Close Bus Isolators of Particular Bus from BCU.

3 No

9

Bus Earth Switches Contact Multiplier

2 No

10

Transfer Bus Coupler Isolators Contact multiplication

2 No

BCU2

BCU3

89BB1 AE CMR

DESCRIPTION

Bus Bar Aux relays

DC -1 DC -2

6

CENTRALISED ARCHITECTURE 2 RBB

BCU1

BCU2

BCU3

BUSBAR-1 RELAY

BUSBAR-2 RELAY

TRANSFER BUS RELAY

89BB2 AE CMR

2 RBB

S.NO

89BB1 AE CMR

DISTRIBUTED ARCHITECTURE

Bus Bar Aux relays

DC -1 DC -2

BUS COUPLER PANEL CONVENTIONAL PANEL

1

50/51 A,B C,N

2

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

Set

TRIP COIL 1&2 HEALTHY LEDS

3

Flag relays two element type for Circuit Breaker Troubles

Set

4

Trip Coil Supervision Relays.

6 No

5

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

2 No

6

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

3 No

IDMT Numerical Non Directional O/C & E/F Relay

1 No

8

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

Set

9

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

1 No

DC-2

86 GR-B CB Contact Multiplier Relay

7

2RBC

1 No BC BCU

LBB/ BU 50Z

LBB/ BU 50Z

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

DC-1

86 GR-A

96 50Z

QTY

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

DC-1

CB TROUBLES & ALARMS

DESCRIPTION

86 GR-A

DC-2

S.NO

2RBC

LBB/ BU 50Z

AUTOMATION PANEL

86 GR-B 96 50Z

CB PB

50/51 A,B C,N

BUS SECTIONALISER PANEL CONVENTIONAL PANEL

1

50/51 A,B C,N

2

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

Set

TRIP COIL 1&2 HEALTHY LEDS

3

Flag relays two element type for Circuit Breaker Troubles

Set

4

Trip Coil Supervision Relays.

6 No

5

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

2 No

6

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

3 No

IDMT Numerical Non Directional O/C & E/F Relay

1 No

8

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

Set

9

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

1 No

DC-2

86 GR-B CB Contact Multiplier Relay

7

2RBS

1 No BC BCU

LBB/ BU 50Z

LBB/ BU 50Z

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

DC-1

86 GR-A

96 50Z

QTY

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

DC-1

CB TROUBLES & ALARMS

DESCRIPTION

86 GR-A

DC-2

S.NO

2RBS

LBB/ BU 50Z

AUTOMATION PANEL

86 GR-B 96 50Z

CB PB

50/51 A,B C,N

TRANSFER BUS COUPLER PANEL AUTOMATION PANEL

CONVENTIONAL PANEL DESCRIPTION

QTY

1

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

1 No

2

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

LBB/ BU 50Z TRIP COIL

TBC BCU

1 No

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

1 No

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

Set

Trip Coil Supervision Relays.

6 No

6

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

2 No

7

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

12 No

8

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

3 No

9

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

Set

10

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

1 No

3

186 86 R1,Y1,B1 GR-A R2,Y2,B2

DC-1

4

286 86 R1,Y1,B1 GR-B R2,Y2,B2 CB 96 Multiply 50Z Relay

DC-2

CB 1&2 TROUBLES HEALTHY & ALARMS LEDS

5

2RTBC

A/R+SC 79+25

LBB/ BU 50Z

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

186 86 R1,Y1,B1 GR-A R2,Y2,B2

DC-1

A/R+SC 79+25

S.NO

286 86 R1,Y1,B1 GR-B R2,Y2,B2 Closing 96 Aux 50Z relays CB PB DC-2

2RTBC

LINE CB RELAY PANEL CONVENTIONAL PANEL 2RLA

AUTOMATION PANEL S.NO

DESCRIPTION

QTY 1 No

50 Z (LBB / BFR)

2

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

1 No

CB TROUBLE ALARAM AND TRIP RELAYS

3

Numerical Breaker Failure Relay. (BFR/CBF/LBB/ Stuck Breaker Protection)

1 No

4

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

SET

5

Trip Coil Supervision Relays.

6 No

6

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

TSR TC-1

DC I & II

86 GR -A

TSR TC-1I

1-PH TRIP RELAYS -6 FOR 21L1

86 GR -B

1-PH TRIP RELAYS -6 FOR 21L2

D/T CH-1 RECEIVE RELAYS

D/T CH-2 RECEIVE RELAYS

BREAKER UNDER VOLTAGE MULTIPLICA RELAY TION RELAY

BAY1 BCU

A/R+SC 79+25

LBB/ BU 50Z

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

2 No

186 R1,Y1,B1 86 GR-A R2,Y2,B2

DC-1

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

7

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

3 No

286 86 R1,Y1,B1 GR-B R2,Y2,B2

DC-2

1

79 + 25 (AUTO RECLOSURE + CHECK SYNC RELAY)

2RLA

8

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

12 No

96 CLSOING 50Z AUX RLYS CB PB

9

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

2 No

10

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

SET

11

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

1 No

12

Under Voltage Relay for Line Isolator Earth Switch Interlock circuit.

SET

13

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

1 No

CB, ISO

D/T CH-1 RECEIVE RELAYS

D/T CH-2 RECEIVE RELAYS

ICT HV or LV CB RELAY PANEL CONVENTIONAL CONVENTIONAL PANEL PANEL S.NO

DESCRIPTION

QTY

1

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

1 No

2

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

3

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

CB TROUBLE ALARAM AND TRIP RELAYS TSR TC-1

86 GR -A

DC I & II

TSR TC-1I

BREAKER MULTIPLICA TION RELAY

6 No

5

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

2 No

6

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

3 No

High Speed Inter trip relays and self resetting

4 No

8

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

SET

9

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

1 No

7

LBB/ BU 50Z

Set

Trip Coil Supervision Relays.

86 GR -B

INTER TRIP RELAYS

1 No

4

96 50Z INTER TRIP RELAYS

BAY1 BCU

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

DC-1

50 Z (LBB / BFR)

2RTRA

86 GR-A

DC-2

2RTRA

AUTOMATION PANEL

86 GR-B CB, ISO

96 CLSOING 50Z AUX RLYS CB PB INTER TRIP RELAYS

10

Under Voltage Relay for Line Isolator Earth Switch Interlock circuit.

Set

11

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

1 No

REACTOR CB RELAY PANEL CONVENTIONAL CONVENTIONAL PANEL PANEL 2RBRA

50 Z (LBB / BFR)

AUTOMATION PANEL S.NO

DESCRIPTION

QTY

1

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

1 No

2

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

3

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

CB TROUBLE ALARAM AND TRIP RELAYS TSR TC-1I

1 No LBB/ BU 50Z

Set

4

Trip Coil Supervision Relays.

6 No

5

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

2 No

6

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

3 No

7

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

SET

8

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

1 No

9

Under Voltage Relay for Line Isolator Earth Switch Interlock circuit.

CB TROUBLES & ALARMS

TRIP COIL 1&2 HEALTHY LEDS

86 GR -B

96 50Z

BREAKER MULTIPLICA TION RELAY

DC-1

86 GR -A

DC I & II

BAY1 BCU

86 GR-A

DC-2

TSR TC-1

2RBRA

86 GR-B CB, ISO

Set

96 CLSOING 50Z AUX RLYS CB PB

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

LINE + REACTOR PROTECTION PANEL 2RLB

S.NO

75A 75B 21L1

2RLRC

LINE PROTECTION PANEL DESCRIPTION

QTY

1

MAIN-1(21L1): Line Distance Protection

1 No

2

MAIN-2(21L2): Line Distance Protection

1 No

3

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

2 No

4

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

2 No

5

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

2 No

6

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

2 No

21L2

75A,B 87R

64R

Reactor Trouble Alarms & Trips

21R

LINE REACTOR PROTECTION PANEL S.NO

DESCRIPTION

QTY

1

MAIN-1(87R): Reactor Differential Protection Scheme

1 No

2

MAIN-2(21R): Reactor Backup impedance Protection Scheme

1 No

3

64R: Reactor REF Protection Scheme

1 No

4

Reactor Trouble Alarms & Trips.

5

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

2 No

6

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

2 No

set

ICT + REACTOR PROTECTION PANEL 2RTRB

75A,B 87T1

87T2

2RBRB

ICT PROTECTION PANEL S.NO

DESCRIPTION

QTY

1

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

1 No

2

MAIN-2(87T2): ICT DifferentialProtection (HZ)

1 No

3

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

2 No

4

Transformer Troubles Alarms & Trips

5

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

2 No

6

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

2 No

7

Over Flux Relays for HV & IV

2 No

50O/L

67IV

BUS REACTOR PROTECTION PANEL

99IV

50STUB

64R

Reactor Trouble Alarms & Trips

S.NO 99HV

87R

Set

Transformer Trouble Alarms & Trips

67HV

75A,B

DESCRIPTION

21R

QTY

1

MAIN-1(87R): Reactor Differential Protection Scheme

1 No

2

MAIN-2(21R): Reactor Backup impedance Protection Scheme

1 No

3

64R: Reactor REF Protection Scheme

1 No

4

Reactor Trouble Alarms & Trips.

5

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

2 No

6

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

2 No

set

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.

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

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.

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.

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 shall be used.

GROUP-A & GROUP-B TRIPPINGS LINE PROTECTION

TRANSFORMER PROTECTION

REACTOR PROTECTION

GROUP-A

GROUP-A

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

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

REACTOR DIFFERENTIAL RELAY (87R) REACTOR BACKUP RELAY (21 R) OIL TEMP HIGH TRIP PRESURE RELIEF TRIP

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-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-B REACTOR REF RELAY (64R) BUCHHOLZ TRIP WINDING TEMP HIGH TRIP LOW/ HIGH OIL LEVEL TRIP FIRE PROTECTION TRIP

PRINCIPLE OF Gr-A & Gr-B SEPERATION BUS BAR PROT

CABLE CABLE

CT

96 BB ABB Network Partner AG

CABLE BUS-1 ISOLATOR SELCTION

BUS-1 CABLE

BUS / LINE PT / CVT SELCTION

COM581

C E

MAIN-1 PROT

86 Gr-A

CABLE

PT BUS-2 ISOLATOR SELCTION

BUS-2 CABLE

MAIN-2 PROT

86 Gr-B

CABLE

PT

TRIP COIL-1

LINE CABLE CABLE

CVT DC SOURCE-1 CABLE

DC SOURCE-2 CABLE

DC -1/2 SELCTION

TRIP COIL-2

LINE PROTECTIONS 21L2 21L1

TRANSFORMER PROTECTIONS 87T2 87T1 CIRCUIT BREAKER RELYS OF TRANSFER BUS COUPLER ABB Network Partner AG

COM581

C E

NORMAL TRANSFER GROUP-A TRIP UNIT 86 Gr-A

GROUP-B TRIP UNIT 86 Gr-B

A/R RELAY (79+25)

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

A

A

B

B

B

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 cooperation 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.

NSD 50

MAIN-1 PROTECTION CARRIER INTER TRIPPING G4AC V9LC 1 LINE

G4AC V9LC 6

IN OUT CARRIER RECEIVE

G4AC V9LC 5

ABB

CR -VE

CS

G4AC V9LC 2

CARRIER SEND

G4AA V9LB 5 G4AA V9LB 6 PANEL-1

NSD 50

21L1

ALARM

+VE

-VE

G4AC V9LC 10 G4AC V9LC 13 G4AC V9LC 14

ABB

G4AC V9LC 9

PANEL-2

THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIP AND CONNECTED IN ANOTHER PANEL

NSD 50

MAIN-2 PROTECTION CARRIER INTER TRIPPING G4AC V9LC 1 LINE

G4AC V9LC 6

IN OUT CARRIER RECEIVE

G4AC V9LC 5

ABB

CR -VE

CS

G4AC V9LC 2

CARRIER SEND

G4AA V9LB 5 G4AA V9LB 6 PANEL-2

NSD 50

21L2

ALARM

+VE

-VE

G4AC V9LC 10 G4AC V9LC 13 G4AC V9LC 14

ABB

G4AC V9LC 9

PANEL-1

THIS IS BACKUP FOR PERMISSIVE/ PROTECTION TRIP AND CONNECTED IN ANOTHER PANEL

DIRECT TRANSFER TRIP – Gr-A 96 BUSBAR PROT PANEL

PANEL-1

87 BUSBAR TRIP

ABB NSD 50

M_CB CONTROL PANEL N T

T NC

DC +VE FROM PANEL

MAIN CB TBC_CB CONTROL PANEL N T

T NC

TBC CB

G4AD V9LC 2

50 LBB/BFR FOR MAIN CB / RAICA N T

G4AD V9LC 1 DC –VE FROM PANEL

50 LBB/BFR FOR TBC CB / RAICA N T

59L1 / OVER VOLTAGE STAGE-1

59L2 / OVER VOLTAGE STAGE-2

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.

7.

59L2 OVER VOLTAGE STAGE-2 OPERATED.

DIRECT TRANSFER TRIP – Gr-B 96 BUSBAR PROT PANEL

PANEL-1

87 BUSBAR TRIP

ABB NSD 50

M_CB CONTROL PANEL N T

T NC

DC +VE FROM PANEL

MAIN CB TBC_CB CONTROL PANEL N T

T NC

TBC CB

G4AD V9LC 2

50 LBB/BFR FOR MAIN CB / RAICA N T

G4AD V9LC 1 DC –VE FROM PANEL

50 LBB/BFR FOR TBC CB / RAICA N T

59L1 / OVER VOLTAGE STAGE-1

59L2 / OVER VOLTAGE STAGE-2

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.

7.

59L2 OVER VOLTAGE STAGE-2 OPERATED.

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.

LBB/BFR FLOW CHART MAIN PROTECTION OPERATED

YES

TRIP MAIN BREAKER

FAULT CLEARED

NO

RETRIP

YES

INITIATE BFR

YES

RESET BREAKER FAILURE SCHEME

WAIT FOR FAULT CLEARENCE

AND

TRIP BACK-UP/ Adjacent BREAKERS

The Breaker Failure Protection (LBB/BFR) can operate single-stage/twostage. 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.

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

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

TIMER +VE

+VE

-VE TO D/T CH-1 TO D/T CH-2 TO ANNUN

86 GR-B 96 BB

NT

50X

In case of Feeder bay / Transformer Bay

TO MAIN1 DR TO MAIN2 DR TO SER TO 86 GR-A TO 86 GR-B TO 96 BB TO BUSBAR

NT

+VE

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

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

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

TIMER +VE

+VE

-VE TO D/T CH-1 TO D/T CH-2 TO ANNUN

86 GR-B 96 BB

NT

50X

In case of Feeder bay / Transformer Bay

TO MAIN1 DR TO MAIN2 DR TO SER TO 86 GR-A TO 86 GR-B TO 96 BB TO BUSBAR

NT

+VE

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

NUMERICAL BUSBAR PROTECTION ¾

¾ 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

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 LBB, EFP and other Protections are inbuilt feature. Ratio Matching Transformers are not required. They can be programmable. Isolator selection is required & selection relays are not required for zone segregation. One Unit is sufficient, for any no of Zones of BUSBAR Protection. In Distributed Architecture Communication between Bay Unit to Central Unit is Fiber Optic connection. Check Zone feature like Over-all Differential Protection & Over Current Starter Protection is in built function. Current comparison, CT supervision, CT open circuit & CT Saturation Detection is also inbuilt feature. Disturbance recorder and event recorders are inbuilt feature. BUSBAR Tripping Relays are Provided in each bay associated CB Relay Panel and tripping through Bay Unit. These can be configured either High or Low impedance BUSBAR Protection.

Traditionally Two Distinctive Architectures (CENTRALISED & DECENTRALISED) Distributed Bus Protection

52

52 DAU

Centralized Bus Protection

52 DAU

52

52

DAU

CU

CU copper

52

copper

fiber

• Fits better new installations • Perceived less reliable • Slower

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

DOUBLE BUS WITH TB- NUMERIC(1) BUS-1

UU

UU

UU

BUS-2

UU UU

UU

UU

UU

AUX BUS

89A

89A

89A

89A

89A

89B

89B

89B

89B

89C ISOLATOR SELECTION

89C ISOLATOR SELECTION

89B ISOLATOR SELECTION

89C ISOLATOR SELECTION

89C ISOLATOR SELECTION

INDIVIDUAL RELAYS FOR EACH BUSBAR

DOUBLE BUS WITH TB- NUMERIC(2) BUS-1

UU

UU

UU

BUS-2

UU

BAY UNIT

BAY UNIT

BAY UNIT

BAY UNIT

BAY UNIT

87BB DISTRIBUTED ARCHITECTURE

BAY UNIT

89A 89B 89C

UU

UU BAY UNIT

89A 89B 89C

89A 89B

UU 89A 89B 89C

89A 89B 89C

UU

AUX BUS

BAY UNIT

DOUBLE BUS WITH TB- NUMERIC(3) BUS-1

UU

UU

UU

BUS-2

UU 87BB CENTRALISED ARCHITECTURE

89A 89B 89C

UU

UU 89A 89B 89C

89A 89B

UU 89A 89B 89C

89A 89B 89C

UU

AUX BUS