Baart sarkar Government of India kond`Iya ivaVut … at Padghe S/S. The distance relay of 220kV Wada...

Minutes of 96th WRPC PCM

Baart sarkar Government of India kond`Iya ivaVut p`aiQakrNa

Central Electricity Authority piScama xao~Iya ivaVut saimait

Western Regional Power Committee ef -3, emaAayaDIsaI xao~, AMQaorI (pUva-), mauMba[- - 400 093

F-3, MIDC Area, Andheri (East), Mumbai - 400 093

Aa[- esa Aao : 9001-2000 ISO : 9001-2000

dUrBaaYa Phone: 022- 28221681 ; 28200194 / 195 / 196; fO@sa Fax : 022 – 28370193

Website : www.wrpc.nic.in E-mail : [email protected] No. Prot./ 96 PCM / 2006-07 / WRPC / 3404 Date: 12th April 2007 To, Sub :- Minutes of 96th Protection Committee Meeting held on 29th & 30th

March 2007 at Vadodara. Sir,

Please find enclosed herewith the minutes of 96th Protection Committee Meeting of Western Regional Power Committee, Mumbai held on 29th & 30th March 2007 at Vadodara for your information and necessary action.

Minutes are also available at WRPCommittee website www.wrpc.nic.in

Thanking you

Yours faithfully,

(S.D. Taksande) Suptdg. Engr.(P.)

Encl. :- As above


MINUTES OF THE 96th PROTECTION COMMITTEE MEETING

The 96th Protection Committee Meeting was held on 29th & 30th March 2007 at

Vadodara. The list of participants is placed at Annex -I.

At the outset, Shri M.K. Iyer, Sr. C.G.M. (F & A), GETCO welcomed the

members and participants to 96th Protection Committee Meeting. He said that it

was a great pleasure for GETCO in holding this 96th WRPC PCM at Vadodara

and thanked WRPC for giving an opportunity to host the Protection Committee

Meeting by GETCO.

Shri S. D.Taksande, Superintending Engineer (Protection), WRPC welcomed

all the participants to the 96th Protection Committee Meeting and informed that

Shri P. Patel, Member Secretary, WRPC could not chair this meeting due to his

presence required in another urgent meeting at New Delhi. He thanked GETCO

for having consented readily to host the meeting at Vadodara. He thanked Shri

M.K. mehta, A.C.E., GETCO and his team of dedicated engineers for the

excellent arrangements made for the meeting and comfortable stay of

participants. He stated that there was no major grid disturbance took place

during the period of this meeting ie. In the last quarter of the year 2006 but

recently two partial grid disturbances took place on 25th & 28th February 2007

emphasizing special attention of experts from various utilities in the field of

protection to review all protection schemes implemented in their respective

jurisdiction. He requested protection engineers to keep operational all

protection schemes including Under Frequency Relays. He emphasized on

monitoring of operation of these relays, load relief obtained and expected for

safe & secured operation of the enlarged grid.

Shri S. D.Taksande, Superintending Engineer (Protection), WRPC, informed

the participants that WRPC PCM Agenda & Minutes are made available on

WRPC website (www.wrpc.nic.in). The agenda items were taken up for

discussion in seriatim.

Item No.1: Confirmation of Minutes of 95th Protection Committee Meeting. Minutes of 95th Protection Committee Meeting of WRPC held on 3rd & 4th


January 2007 at TAPS-3&4, Tarapur were circulated vide WRPC letter no.

Prot./95-PCM/2006-07/WRPC/602 dated 22nd Jan. 07. No comments were

received from any of the members.

The minutes for 95th Protection Committee Meeting were confirmed.

Item No.2: System disturbances 2.01: System disturbance at 400 kV Koradi S/S in MSETCL system on 09-10-2006 The representative of MSETCL explained that on 09.10.2006 at 05:33Hrs,

while withdrawing the Generating Unit # 2, connected to 220kV Main Bus-I, its

LBB relay operated and resulted in tripping through respective 96 relay of all

breakers including Bus Coupler connected to 220kV Main Bus-I. On

investigation, both trip coils of the BHEL make MOCB, manufactured &

commissioned in 1987, of Generator Unit # 2 were found burnt.

After isolating the Gen. Unit # 2, 220kV Main Bus–I was restored by 7:40 Hrs

on the same day.

Committee observed that while withdrawing the set, trip command was sent to trip MOCB provided for the Generating Unit but as both the trip coils were burnt, MOCB could not open and LBB operated. Tripping of all breakers connected to Main Bus-I, along with Bus Coupler, on operation of LBB protection is in order. MSETCL informed that all the four Generating Units connected to 220kV Bus are provided with MOCBs. MOCBs are having mechanical problem in its tripping mechanism and are under replacement in R/M scheme by SF6 breakers. 2.02: Equipment failure at 220kV Osmanabad S/S in MSETCL system on 12-10-06 The representative of MSETCL explained that on 12.10.2006 at 06:20Hrs,

220/33kV, 25MVA CGL Make Power Transformer Sr. No. T-8297, two sets of

33kV BHEL make VCBs (one Set of Upala feeder and other of LV side of

stated transformer) and 6 Nos. 33kV, Indian Transformer Co. Boisar Make

CTs failed at 220kV Osmanabad S/S due to a 33kV feeder fault which got


converted in to close up 33kV Bus fault due to non tripping of breakers of

feeder and the transformer in spite of operation of their respective protections.

Isolation of fault took place only after tripping of 220kV lines on Distance

Protection from remote end Sub-stations at Parli and Solapur.

The respective protections at the Sub-station operated correctly but due to

inadequate D.C. voltage, the breakers failed to operate and ultimately the fault

was cleared from remote ends correctly. On detailed checking after

occurrence it was revealed that charger AC supply MCB was in tripped

condition and battery DC voltage was of the order of 120-130volts as against

220V. After replacement of two-three weak cells, DC supply was restored to

the level of 170Volts, sufficient to make breakers “ON” of 220kV incoming line

and 220/33kV transformer at the substation.

Normalcy restored by 11:10Hrs on 12.10.2006.

Committee opined that very low battery DC voltage, due to high battery resistance for weak cells, during non-availability of DC supply through charger is the reason for non operation of trip coils of breakers which resulted in conversion of a 33kV feeder fault into close up 33kV Bus fault. Committee recommended that effective monitoring systems and maintenance practices should be followed for battery and battery charger. Battery voltage & decay of cells should be checked at regular intervals by switching “OFF” the battery charger and also by measuring battery impedance.

Committee also recommended for providing LBB and Bus Bar scheme for 220kV Osmanabad S/S.

2.03: ICT failure at 400kV New Koyna S/S in MSETCL system on 29-10-2006 The representative of MSETCL explained that on 29.10.2006 at 04:58Hrs,

3x105MVA, 400/220/33kV ICT No.-1 having load of 90A on HV side, tripped


at 400kV New Koyna S/S on differential protection. Both the HV and MV CBs

tripped. As there was no visual damage in the jurisdiction of differential zone,

the ICT was isolated from both ends and tests such as ‘Turns ratio test for

ICT’, ‘IR values and Primary injection of HV and MV CTs’, ‘ IR values of HV,

LV and MV of ICT and LAs’, ‘BDV of oil of ICT’ and ‘Relay testing’ etc were

carried out. Tertiary Y-phase bushing of the ICT was suspected damage.

Also, during relay testing, NDR relay of the ICT was not picking up –

defective. In this occurrence, the NDR should also have picked up but it being

defective did not operate.

After necessary testing, the ICT was recharged at 12:20Hrs on 02.11.2006

without NDR relay in view of generation from Dabhol and to have redundancy,

and stood ok. At 12:40Hrs on 02.11.2006 ICT was loaded up to 110A on HV

side. The defective NDR relay was replaced on 04.11.2006.

Committee observed that tripping of ICT on differential protection is in order for damage in Tertiary Y-phase bushing of ICT. Committee recommended for regular check up of tan-delta measurement of Tertiary winding of transformer as well. Also, regular check up of healthiness of relay (NDR) is recommended since defect in NDR was observed during investigation, which could have been avoided. 2.04: System disturbance at 400/220kV Padghe S/S in MSETCL system on 16-11-06 The representative of MSETCL explained that on 16.11.2006 at 22:04 Hrs,

W.S. make 220kV B-phase C.T. in respect of 220kV Padghe – Wada feeder

burst at Padghe S/S. The distance relay of 220kV Wada feeder at Padghe

had sensed the fault in B-E, Zone-I correctly, however, the fault subsequently

turned to bus fault during bursting of C.T. and 220kV Bus Bar protection

operated resulting in tripping of all lines & equipments, including Bus Coupler,

connected to 220kV Main Bus –II at 400/220kV Padghe S/S.

At 220kV Wada S/S, the distance relay cleared the fault in Zone-I, B-E when

the fault is in Zone-II from Wada. The distance scheme at Wada is being

tested.


At the time of this occurrence, the 400kV Padghe – Tarapur line II tripped on

over voltage. The voltage sensed was 242.9kV. The over voltage signal was

transmitted to Tarapur end through carrier. Thus CBs tripped at Tarapur and

Padghe ends.

400kV Padghe – Boisar line tripped at Padghe end only on distance

protection B-E indicates mal-operation. The distance relay LZ96 (ABB make)

at Padghe in respect of 400kV Boisar line had been replaced by REL 521

ABB make on 21.01.2007 after necessary testing. The load thrown at Padghe

S/S during the occurrence was 374MW.

All tripped lines & equipments were restored between 23:26Hrs on

16.11.2006 and 00:42Hrs on 17.11.2006 except 220kV Padghe – Wada

feeder which was restored at 21:04Hrs on 17.11.2006 after replacing the

damaged C.T. by ABB make C.T.

Committee observed that load throw due to 220kV Bus isolation might have caused Over Voltage on 400kV Bus leading to tripping of 400kV Tarapur – Padghe # 2. The reason of multiple grounding in panel given by MSETCL for O/V, seems to be inadequate, however the multiple groundings needed removal. MSETCL informed that LZ 96 relay of 400kV Padghe – Boisar at Padghe end has been replaced by REL 521 ABB make relay. 2.05: System disturbance at 220kV Aarey S/S in REL system on 25-11-2006 The representative of REL explained that on 25.11.2006 at 19:16 Hrs, 220kV

Aarey – Borivali Line-2 tripped on distance Protection Zone-I, Y Phase (RYB)

at both ends i.e. Aarey and TPC – Borivali end on genuine fault.

Simultaneously during the fault, the LBB protection of Numerical Relay

MICOM P127 on the parallel feeder 220kV Aarey – Borivali Line –1 mal-

operated and its LBB element operated tripping feeders namely 220kV Aarey

– Borivali #1, 220kV Aarey –Versova #1 and 100MVA transformers-1 & 3


including Bus Coupler connected to 220kV Main Bus – I.

This resulted in disconnection of REL 220kV system from TPC system as

both the TPC interconnecting lines tripped. Thus REL system got islanded

from the WR grid and survived after effecting 273MW load shedding. DTPS

units survived along with loads of Versova, Ghodbunder & part of Aarey.

At 20:19Hrs, REL system was synchronized with TPC and total 33kV feeder

restoration was carried out by 20:40Hrs on the same day.

Committee observed that CB trip condition required for LBB operation must be pre existing and second condition of current requirement met due to tripping of 220kV Aarey – Borivali Line-2 and hence LBB in respect of 220kV Aarey – Borivali Line-1 operated. Committee recommended that ground and DC leakage of P127 relay should be checked up properly. REL informed that the maloperated MICom P127 was sent to Areva for detail investigation. 2.06: System disturbance at 220 kV Navsari S/S in GETCO system on 01-12-2006 The representative of GETCO explained that on 01.12.2006 at 01:50Hrs,

220kV Navsari – Nashik # 2 tripped from both the ends on distance

protection. The other line 220kV Navsari – Nashik # 1 also tripped from

Nashik end only on distance protection in Zone-3 for R-E fault, A/R lock-out.

The CB of 220kV Navsari – Nashik # 1 from Navsari end did not trip. No other

line tripping or disturbance occurred at that instance. The S/S is having single

main bus with transfer bus arrangement and all the bays were connected to

main bus. From the Disturbance Report retrieved from REL 511 relay of

220kV Navsari – Nashik # 2, it was observed that R-ph pole of Circuit Breaker

of the line at Navsari end opened after lapse of @ 910 mS which resulted in

persistent fault feeding in the faulty 220kV Navsari – Nashik # 2 line from

Navsari end. 220kV Navsari – Nashik # 1 was in charged condition from

Navsari end and the other end tripped. The breakers of 220kV Navsari –


Nashik lines are very old manufactured in 1969, HBB make, ABCB type.

GETCO informed that breaker is being replaced and also MM3 relays being

replaced by Numerical relays.

220kV Navsari – Nashik # 2 line was charged at 03:03Hrs on the same day.

Committee analysed the occurrence and observed that 910ms time taken to trip faulty feeder 220kV Navsari – Nashik # 2 might have caused relay of 220kV Navsari – Nashik # 1 to trip in Zone-3 at Nashik end, as except 220kV Navsari – Nashik # 1 other feeders have MM3 relays and due to low fault current, relays might not have operated. There is no LBB protection scheme provided at S/S, so other feeders did not trip on LBB. Also Nashik being the nearest generating station, a strong source, might be the reason for tripping of the feeder from Nashik end only. Committee recommended for sectionalizing of the bus and also for provision of LBB protection scheme at 220kV Navsari S/S. 2.07: System disturbance at 220 kV Ranasan S/S in GETCO system on 10-12-2006 The representative of GETCO explained that on 10.12.2006, 132kV Y ph C.T.

of 132kV Ranasan – Sabarmati # 2 at 220kV Ranasan S/S was replaced by

reconditioned C.T. due to oil leakage of the C.T. After necessary testing line

was charged at 17:50Hrs and stood OK. At 18:35Hrs, the reconditioned C.T.

failed due to fire and breaker of 132kV Ranasan – Sabarmati # 2 tripped.

Also, simultaneously 220/132kV 150MVA Transformer No. 4 failed and caught

fire resulting in complete damage. All the lines and transformers connected to

132kV Bus except Chiloda, Talod, Vijapur & IPRL (Radial) tripped.

All tripped elements except 132kV Ranasan – Sabarmati # 2 and 220/132kV

150MVA Transformer No. 4 were restored between 22:06 Hrs & 22:55Hrs on

the same day. After C.T. replacement, 132kV Ranasan – Sabarmati # 2 was

charged on 12.12.06 at 18:45Hrs.

Committee observed that as C.T. was on bus side, fault current


persisted for longer duration. Heavy fault current fed by all the four transformers and transformer no. 4 got affected and caught fire. Therefore, Committee recommended for replacement of location of C.T. from bus side to line side and provision of REF protection on all existing 220/132kV & 132/66kV transformers. Committee also recommended for two bus arrangement and Bus Bar protection scheme at the important Ranasan S/S. GETCO informed that renovation of S/S with numerical relays and other R & M activities are under way and will be completed within three months time.

2.08: System Disturbance at TAPS 3&4 in NPCIL on 01-10-2006 The above disturbance was discussed in 95th PCM held at TAPS-3&4 wherein

representative of NPCIL explained that on 1-10-2006 at 22.23.31.500, 400 kV

Tarapur- Padghe-II tripped on directional earth fault with C-phase to ground

fault indication and disturbance recorder data showing an earth fault current of

500A (Relay setting 200A-1sec time delay) maximum varying from a value of

152A to 500A in around 5 seconds. The fault resistance was such high that

the distance protection at local/remote end could not detect a fault and TAPS-

3&4 Main-II relay tripped on directional earth fault (backup protection). Exactly

one sec after this incident i.e. at 22:23:32:500 400 kV Tarapur-Padghe ckt-I

tripped on zone-3 with a DTF of 192.7kM. Around 1.4 sec after that 400 kV

Padghe ckt –II remote end tripped on zone-II with a DTF of 92kM. The C

phase voltage dipped to 54.3kV ie the fault resistance reduced to drastically

but due to absence of permissive signal the relay tripped after Zone-2 time.

It was felt that the fault existed on 400kV Tarapur-Padghe ckt-II very near to

the TAPS 3&4 Switchyard but nothing abnormal was found even after

thorough yard survey. It was during night with heavy rains and so it was

concluded that an arcing discharge had occurred in the line at that time which

was transient in nature.

The fault in the 400 kV Tarapur- Padghe-II line could not be cleared until it


transformed into a low resistance fault. The non-operation of main/backup

protection at remote end of 400 kV Tarapur- Padghe-II led to unwarranted

outage of 400 kV Tarapur- Padghe-I. As such, proper co-ordination of

resistive reach settings at both the ends is required to be done to avoid

unwarranted tripping of healthy line or even generator.

In 95th PCM, Committee observed that relay co-ordination has to be achieved at both Tarapur and Padghe. Committee discussed at length all the aspects of relay co-ordination and concluded that some more inputs and deliberations were required, therefore, it was suggested that MSETCL, PGCIL and TAPS-3&4 would sit together and mutually decide the relay settings. All the three utilities agreed to sort out the problem within shortest time. However, it was learnt from TAPS-3&4 and MSETCL representatives that no meeting was convened for corrective action in the matter.

As decided by the Committee during 95th PCM, matter was to be sorted out in a meeting between NPCIL, MSETCL and POWERGRID. The meeting could not be held earlier and is now scheduled on 10th April 2007 at TAPS –3&4 station to achieve relay co-ordination so that healthy line does not trip for a fault on other line. Item no. SA2.09: System Disturbance at 220kV S/Ss Satna & Rewa in MPPTCL system on 10.10.2006 The representative of MPPTCL explained that on date 10-10-2006 at 08:28Hrs, due to flashover at location No. 911716 on 220kV Rewa – Tons # II feeder, 220kV Satna – Tons # II and 220kV Rewa – Tons # II both feeders connected to 220kV Bus –II at Tons tripped from Satna and Rewa end whereas there was no tripping at Tons Hydel Power House end. 220kV Rewa – Tons # 1 connected to Bus-I at Tons was not in service due to system high voltage. 220kV Satna – Tons # I connected to Bus-I at Tons remained charged from both ends. There was no interruption to supply at 220kV Rewa & Satna. Normalcy restored between 09:40Hrs to 10:20Hrs on the same day. Committee observed that as there was no LBB at 220kV Tons S/S, the non tripping of C.B. of 220kV Rewa – Tons # II at Tons resulted in tripping of other line i.e. 220kV Rewa – Tons # II tripped at Satna on E/F / why DPR at Satna did not operate needs investigation. Committee recommended for investigation in C.B. non tripping at Tons and suggested for replacement of existing breakers with SF6 breakers. Item no. SA2.10: System Disturbance at 220kV S/S Sarni in MPPTCL


system on 23.10.2006 The representative of MPPTCL explained that on date 23-10-2006 at 20:20Hrs, due to melting ‘B’ phase jumper of 220kV Satpura Power House feeder, connecting the 220kV Incoming feeder to wave trap top clamp, disconnected from wave trap at 220kV S/S Sarni. As the Incomer Bay at 220kV S/S Sarni end is not fully equipped, 220kV Sarni feeder at Satpura Power House S/S, 132kV Sarni – Chhindwara feeder at 132kV Chhindwara S/S and 132kV Sarni – Khappaswami feeder at 132kV Khappaswami S/S tripped at remote ends. Normalcy restored between 20:28Hrs to 21:00Hrs on the same day. Committee recommended that

- 220kV Sarni feeder bay should be immediately fully equipped so that fault can be cleared.

- ICTs did not trip on O/C as Chindwara is a weak source, therefore, ICTs should be provided with Directional Earth Fault Protection.

- Thermovision should be carried out on line and equipments regularly.

Item no. SA2.11: System Disturbance at 400kV S/S Nagda in MPPTCL system on 01.11.2006 The representative of MPPTCL explained that on date 01-11-2006 at 04:20Hrs, 315MVA Transformer No. I, II & III tripped on over load resulting in interruption to 400kV S/S Nagda, 220kV S/Ss at Ujjain, Nagda, Barnagar, Ratlam & Neemuch and to many 132kV Sub Stations in the area. Though load- dropping scheme for 315MVA transformers provided to trip feeders/Xmers at 220kV S/S at Nagda operated but it could not extend desired load relief. To avoid the reoccurrence, load-dropping scheme is now modified to obtain load relief of approximately 435MW at 400kV S/S Nagda. Normalcy restored between 04:50Hrs to 05:00Hrs on the same day. Committee opined that there should be overload alarm in advance well before tripping criterion on 400kV 3x315MVA Xmers so that preventive action could be taken to avoid Xmer tripping. Committee also suggested that load dropping scheme framed should be operational all time. MPPTCL informed that load - trimming scheme has been modified to give load relief of approximately 435MW and the scheme has been implemented. Item no. SA2.12: System Disturbance at 220kV S/S Barwaha in MPPTCL system on 19.11.2007 & 21.11.2006. The representative of MPPTCL explained that on date 19-11-2006 at 21:55Hrs, 220kV Khandwa – Dewas feeder tripped from both ends. To avoid over loading of Transformers at 400kV S/S Indore, the load of 220kV S/S


Dewas was diverted to Khandwa through 220kV Khandwa – Barwaha feeder, Barwaha – Ujjain (Indore) & Indore – Dewas feeder by keeping these feeders on auxiliary bus at Barwaha & Indore. For tracing the faulty section, 220kV Khandwa – Dewas feeder was sectionalized and was charged section wise. 220kV Khandwa – Barwaha section of the feeder was charged from Barwaha end & it stood OK. When the 220kV Barwaha – Ujjain (Indore) charged from Barwaha end only up to Indore, it did not hold & tripped. At the same time BHEL 1974 make, C phase C.T. of 220kV Barwaha – Ujjain (Indore) feeder failed at Barwaha end damaging other CT and total supply at 220kV S/S Barwaha failed. Normalcy restored on 23.11.2006 at 09:45Hrs. Committee opined that C phase C.T. of 220kV Barwaha – Ujjain (Indore) feeder had failed but did not burst or shattered, therefore second charging was attempted. Also C.T. was on line side, no bus bar protection operated and other feeders tripped from other end. Committee recommended for stopping non standard practices and adopting only standard practice while shifting lines from one bus to other / Auxiliary bus. Item no. SA2.13: System Disturbance at 400kV S/S Nagda in MPPTCL system on 04.12.2006 The representative of MPPTCL explained that on date 04-12-2006 at 01:20Hrs, 220kV Nagda – Ujjain # I tripped from both ends. On charging of the feeder from Nagda end, DPR again operated but circuit breaker failed to trip resulting in tripping of 3X315MVA Transformers at 400kV S/S Nagda and causing interruption to various places. On patrolling the fault was found on 220kV Nagda – Ujjain # I at location No. 143 where all the discs of R phase found flashover and R phase conductor found resting on middle cross arm. Normalcy restored between 02:50Hrs to 03:50Hrs on the same day. Committee observed that there is no bus bar protection scheme at 220kV Nagda S/S and 3x315MVA Xmers tripped on 220kV side. Committee, therefore, suggested for bus bar protection scheme at 220kV Nagda S/S and also ICTs should have directional E/F protection instead of non-directional one. Also, two trip coils should be in parallel with different D.C. source for circuit breaker tripping.

ITEM NO. 3: Tripping of lines / ICTs: The incidences of tripping of lines and ICTs during the period 01-10-2006

to31-12-2006 were discussed during the meeting.

Observations of the committee are enclosed at Annex –3. ITEM NO. 4: Information on A/R, DR and SER in Western Region: PCM forum is monitoring the progress and working conditions of A/R, DR and


SER in Western Region. During the meeting Superintending Engineer

(Protection), WRPC specifically requested all the constituents to furnish the

details of 400kV lines and 400kV Sub stations where these facilities are not

provided yet or provided but not in working condition. Action proposed for

rectifying the faulty A/R, D/R and SER may be informed to WRPC. Also,

change in status furnished by constituents, if any, be made available to

WRPC. ITEM NO.5: Special Protection Scheme – Run back of generating stations: During 95th PCM, Member Secretary, WRPC informed the Committee that

Northern and Central (WR-ER-NER) Grids are operating in synchronous

mode since 26th August 2006 with the commissioning of 400kV Gorakhpur –

Muzaffarpur double circuit line (ER-NR A.C. link). It may be noted that when

both 400kV Muzaffarpur – Gorakhpur lines are in service along with Tala HEP

and other additional generation in ER, then tripping of these lines might cause

serious overloading of lines in WR and thereby in-secured operation of WR

grid necessitating for a Special Protection Scheme.

NR and WR are receiving power from ER, since source of surplus generation

is in ER. As such, generation in ER is required to be reduced in the event of

tripping of any of ER–NR or ER–WR AC links to restrict the overloading and

resultant disturbance in the region. Accordingly, the following scheme was

proposed and approved in the 2nd meeting of WRP Committee held on 12th

Oct.2006.

“Since NR & WR connected through ER, separation of regions can be

sensed through sudden frequency rise in ER. In order to control tie-

line flows from ER, it is essential to back-down generation

automatically in ER. Normally, the flows on ER-NR links will be to the

tune of 1500MW on an average and assuming the flows on ER-WR

link is about 1500Mw and further loading is to be avoided, then there

will be a need to back-down generation in ER generating stations by

1500MW to retain pre occurrence conditions. ER has about 5 units of


500MW and considering HP/LP bypass action, the load on 500MW

units can be reduced by 1500MW as 60% of the steam is bypassed.

The action can be triggered at 50.8 / 51.0 Hz. This would reduce /

maintain the tie line flows to the only region connected to ER”.

The views of WRPC were conveyed to ERPC for their consideration and

implementation. ERPC deliberated the above proposal in their forum and

opined that tripping of ER-NR / ER-WR links might not always result in rise of

frequency up to 50.5Hz and that backing down of 1000MW of generation in

ER might lead load shedding to ER consumers. The ER constituents had

requested that Special Protection Scheme might be prepared by CEA

considering the overall aspect of grid security and future planning of the entire

NER-ER-WR-NR grid.

WRPC in its 3rd meeting held on 28th February 2007 had desired that the

finalisation of Special Protection Scheme by CEA may be expedited at the

earliest as implementation of this scheme would greatly reduce the risk of

major grid disturbances in the integrated grid. Accordingly, WRPC has

requested CEA for any other alternative scheme in the matter.

Committee noted.

ITEM NO.6: Frequent tripping of 400kV lines emanating from SSP on over voltage Protection: Superintending Engineer (Protection), WRPC informed that incidences of

high voltage at 400kV SSP S/S resulting in frequent tripping of 400kV lines

emanating from SSP i.e. 400kV SSP –Dhule # 1 & 2, 400kV SSP-Nagda # 1

& 2, 400kV SSP – Asoj & 400kV SSP – Kasor on over voltage protection

was discussed during the 372nd Operation & Co-ordination Committee

(OCC) Meeting of WRPC on 9th February 2007 wherein it was suggested

that all over voltage relays on 400kV lines evacuating power from SSP are to


be set at 110% with time co-ordination. Narmada Control Authority (NCA),

vide their letter No. 3/1/2006/Power/276 dated 12/13th February 2007 have

taken up the matter with concerned utilities for remedial measures.

All concerned utilities confirmed that, in consultation with GSECL, they have co-ordinated the relay setting at remote ends Dhule, Nagda, Asoj and Kasor. Moreover machines at SSP have been tested for operation in synchronous mode for controlling the high voltage problem. ITEM NO.7: Follow up points:

7.1: A/R scheme of 400kV Tarapur – Boisar ckt. 1 & 2 and 400kV Tarapur – Padghe ckt 1 & 2 at Tarapur NPCIL end

Presently the A/R selector switch of all the 400kV lines emanating

from TAPP 3 & 4 is kept in non-auto mode at TAPP end. NPCIL

agrees in principle to the view that single phase auto re-closure

on all 400kV lines should be commissioned to improve the

transient stability of the regional power system. At the same time,

NPCIL is of the view that the prime mover of the nuclear units

vary in design from their counterparts of thermal stations and the

suitability of the prime mover at the generating station needs to

be ascertained before provision of auto re-closure feature on the

lines emanating from Nuclear Power Station. Accordingly, NPCIL

have referred to manufacture BHEL for indicating the suitability of

the prime mover for the auto re-closure duty.

NPCIL representative informed that so far they have not received any communication from the manufacturer. Action based on the recommendation of the manufacturer would be taken in the matter. Superintending Engineer (P), WRPC advised NPCIL to expedite the feedback from the manufacture, so that A/R scheme is implemented at both ends for stability of system.

7.2: Commissioning of PLCC system in 220kV lines of other utilities emanating from POWERGRID sub – stations


WRPC Protection Committee has agreed to follow CBI&P guidelines in

the above matter. As per CBI&P manual, there should be at least one

carrier aided non-switched three-zone distance protection scheme to

protect 220kV line. Accordingly, Committee has time and again

emphasized the need for early commissioning of PLCC panels and

protection couplers wherever to be provided.

A. Khandwa Sub-station:

Four nos. 220kV lines of MPPTCL are connected to Khandwa S/S

of Powergrid. These lines were commissioned in the year 2005.

The protection coupler had not been procured at both ends, the

same needs to be procured and commissioned by MPPTCL at the

earliest.

MPPTCL representative informed that commissioning of Protection Couplers for all the lines 220kV Nepa Ckts. 1 & 2 and that of 220 KV Julwania & Barwaha will be completed within three months. Relays for 220 kV Julwania ckt are expected by the end May, 2007.

B. Commissioning of Carrier inter trip scheme on 220kV lines of MSETCL

MSETCL representative informed that the carrier aided protection had been provided in respect of 220 kV Padghe-Boisar (PGCIL) line & 220 kV Boisar (MSETCL) – Boisar (PGCIL) line. Carrier aided inter-tripping protection has been taken into service in respect of 220 kV Boisar (MSETCL)-Boisar (PGCIL) line on 05.02.07. The present status of carrier inter-tripping protection is as under:

Sr. No. 220 kV line Date of commissioning of carrier inter-tripping

protection 01] Tarapur-Boisar-II 16/10/94 02] Tarapur-Borivali 17/12/02 03] Trombay-Tifil 06/07/05 04] Nagothane-Apta 08/08/06 05] Nagothane-Mahad 17/08/06 06] Kalwa-Mulund-I 23/08/06 07] Kalwa-Borivali 24/08/06


08] Kalwa-Apta 24/08/06 09] Kalwa-Taloja 29/08/06 10] Washala-Raymond 22/11/06 11] Padgha-Boisar (PGCIL) 07/12/06 12] Kalwa-Mulund – II 19/12/06 13] Boisar(MSETCL)-Boisar

(PGCIL) 05/02/07

14] Kalwa - Kharghar 07/02/07 15] Khargar - Kandalgaon 23/02/07 16] Boisar-II - Nalasopara 02/03/07

Committee noted.

7.3: Problem of PLCC in 400kV Korba-Raipur Ckt.# 2

The problem in one PLCC channel, 200 Rx / 252 Tx kHz is still

persisting even after removing jumper at one location. The

signal levels in other PLCC channel 136/140 KHz has been

found normal in ideal condition and this signal levels getting

disturbed during fault condition.

Committee during earlier PCM felt that one of the additional

jump-ring still existing should be removed to improve the

performance. Alternatively, other possibilities for improving

PLCC signal levels on priority may be explored.

POWERGRID representative informed that 400KV Korba –

Raipur Ckt.2 would become LILOed at 400 KV Batarapra

(Powergrid) sub-station. The LILO work would be carried out in

the month of April/May ‘07. After this, length of line shall be

reduced and in turn result in less loss of PLCC signals. The

performance of PLCC levels shall be observed after LILO at

Batapara and action will be taken accordingly.

Committee suggested for reviewing the performance of

PLCC after LILO work completed and if no improvement

observed then still existing additional jump-ring be

removed.


7.4: Replacement of LZ 96 (ABB) relay in respect of 400kV

Padghe – Boisar line at 400kV Padghe S/S: MSETCL representative informed that the PGCIL had procured

new REL 521 (ABB) make relay for replacement of LZ 96 (ABB)

in respect of 400kV Padghe – Boisar line at 400kV Padghe S/S.

After necessary testing, the relay was taken in service on

20.01.2007.

Committee noted. 7.5: Commissioning of Bus Bar Protection Scheme at 220kV

Borivali S/S in MSETCL: MSETCL representative informed that the Bus – Bar Protection

Scheme of ABB make type REB500 has been provided for

220kV bus at Borivali Sub – station on 01.09.2006. Committee noted.

7.6: Non –auto reclosing of 400 kV Vindhyachal- Jabalpur lines.

POWERGRID representative informed that in case of B-phase

to earth fault, the auto re-closing of 400 kV Vindhyachal-

Jabalpur Ckt- 3 & 4 is not taking place at Vindhyachal, while the

same is taking place at Jabalpur end in all the incidences. The

problem was suspected to be of CGL make breakers. M/S CGL

had suggested some modifications in the breaker, which were

intimated to NTPC Vindhyachal. POWERGRID had carried out

such modifications at their end wherever CGL breakers are

commissioned.

During 95th PCM, Committee suggested POWERGRID to supply material

regarding modifications carried out in CGL make breakers at their end and

correspond with VSTPS, NTPC for their comments. Details on modification as

received from POWERGRID are placed below for benefit to NTPC & other

utilities:

REPORT ON MODIFICATION IN CGL MAKE CIRCUIT BREAKERS.


Prior to modification:

Auto-reclose of ‘B’ phase gets blocked most of the time during single phase B ph to earth fault due to mal-operation of pressure switch of Auto reclosure circuit.

Details modification done:

Matter taken up with M/s CGL, Nasik to investigate the cause of mal-operation. M/S CGL has conducted certain experiments with alternate piping arrangement from Air receiver to Auto reclosure Air pressure switch (63AR). This modification can be done at site itself and needs certain spares (adopter, connectors etc.). This modification has been carried out in all CGL make CBs at POWERGRID sub-stations.

After Modification

After modification the performance of auto reclosing during single phase, transient B ph to earth fault is found to be satisfactory. For further details, the address of concerned CGL representative is given below:

Shri Bipin N.Deo Sr. Executive – Sub-station Services M/s Crompton Greaves Ltd., Switcher Gear complex, A-3, MIDC Area, Ambad NASIK – 422010 Phone: 0253 – 2382271 Mobile: 09373917340

NTPC representative informed that VSTPS had carried out the modifications on CGL breakers during the month of March 2007.

Modifications on Jabalpur end already done.

ITEM NO.8: Other grid points:

8.1: Discrepancy in A/R of 400 KV Raipur – Sipat line at NTPC end during tripping on 19.12.2006:

POWERGRID representative informed that during tripping of 400 KV

Raipur – Sipat line on transient R ph. to earth fault, no permissive

carrier has been received from Sipat end, although Main-I & Main-II

relays sensed the fault in Z1 & Z2 at Sipat end. At Raipur end, the Z1

of relays has been time delayed by 100 mS due to presence of Series


Capacitor & it becomes instantaneous only on receipt of permissive

carrier from remote end. Non-transmission of permissive carrier from

Sipat end needs to be looked into. Further, fault locator reading

received from Sipat end is also erratic. Committee suggested for relay co-ordination by NTPC SIPAT.

8.2:Problem in 400kV Itarsi - Bhopal # 1 tie CB at 400kV Itarsi SS:

POWERGRID representative informed that at 400kV Itarsi SS, tie CB

(ABB make) of 400 kV Bhopal Ckt.1 was taken out of service since

17.10.2006 due to failure of actuator housing of drive unit. Matter has

been taken up with MPPTCL to expedite the rectification of the same.

MPPTCL representative informed that the tie CB would be

rectified & restored within 15 days.

8.3: Tripping of 400 KV Tarapur – Padghe Ckt. 1&2 and Tarapur – Boisar Ckt.1 & 2 / System Disturbance at TAPS 3&4 in NPCIL on 14.01.2007:

POWERGRID have intimated that 400 KV Tarapur – Padghe Ckt. 1&2

and 400kV Tarapur – Boisar Ckt.1&2 tripped simultaneously at 19:02

hrs on 14.01.2007 due to failure of ’Y’ ph. Bus-2 PT at Tarpaur end and

direct trip command received at Padghe & Boisar ends. As such

PGCIL enquired for the reason for simultaneous tripping of both Bus-

1&2 for the failure of Bus-2 P.T.

TAPS-3 & 4 representative stated that it was an occurrence at TAPS-

3&4 on 14.01.07 at 19:02Hrs when 400 KV Tarapur – Padghe Ckt.1&2,

400kV Tarapur – Boisar Ckt.1&2 and GT # 3 & 4 tripped at TAPS end

on operation of LBB and at remote ends feeders tripped on receipt of

D/T command due to failure of ’Y’ ph. Bus-2 PT at Tarpaur end, leading

to a Y ph to ground Bus fault. Due to this fault, Bus Differential relay for

Bus-2 along with Check zone operated (PBDCB scheme). But due to

problem in one NC contact for supervision relay, which is wired in


series with the main differential contact, the trip to zone-2 feeders could

not get extended. Later upon investigation it was found that a Spacer in

the auxiliary relay for Bus differential supervision got melted and stuck

to the base. This led to the supervision contact of the relay remaining in

operated condition (ie NO condition) due to which command for Bus

differential could not be extended for tripping. This relay was tested in

September 2005 end due to frequent operation of zone-2 supervision

element and found to be operating satisfactorily in the tests,

Subsequent to the test once the supervision relay again operated and

resettled after some time. Subsequent to this incident, no alarm or

indications were found on the relay. Later this relay was in service till

the occurrence without any noticeable problem. Due to failure of this

contact, Bus differential could not extend trip and with a bus fault the

Zone-4 starters of lines initiated LBB and after 200ms initiated Bus

Differential for both the buses which tripped all the feeders connected

to both the buses and also tripped line remote end breakers as LBB

protection is wired to extend direct inter trip to remote end.

TAPS 3& 4 further concluded the analysis as below:

The event was triggered due to failure of 400kV Bus-2 Y ph PT.

Similarly Bus differential did not operate due to problem in supervision

contact. It is believed that the operation of supervision relay for Bus

differential in September 2005 lead to changing over of contacts for the

Bus differential supervision relay and contact spacer of this relay got

melted due to this changeover. Due to problem in NC contact of

supervision relay, the trip could not get extended which lead to non-

tripping of Zone-2 breakers. Due to the instantaneous initiation of

Zone-4 given by 21M2 relay (EPAC-3000), the LBB protection

operated for all the lines tripping all feeders on both the 400kV buses

200msec after the incident.

The Zone-4 LBB contacts were found to operate instantaneously

for EPAC-3000 were later rectified in consultation with Areva T &

D engineers.


8.4: Interconnection of REL and MSETCL at Boisar S/S of MSETCL: At present 220kV REL network is radially connected to 220kV TPC

system. As per REL’s letter No. TD-112/MSR/2006 dated 05.02.2007,

STU has approved the interconnection of REL with 220kV Boisar S/S of

MSETCL through LILO of 220kV Dahanu – Versova ckt # 1. Thus the

existing islanding scheme will have to be modified to suit the new

scenario.

MSETCL representative informed that a meeting is proposed on 3rd April’07 at MSETCL HQ to discuss the matter. Committee suggested to incorporate the decisions of that meeting while modifying the existing islanding scheme.

SA 8.5: Problems in newly commissioned GETCO bays at Dehgam SS:

POWERGRID has informed that M/S GETCO has commissioned the

DRs & Event logger at Dehgam S/S on 08.03.2007. During the tripping

of 400kV Dehgam – Soja line on 09.03.2007, the following

discrepancies were noticed:

a. Disturbance Recorder: At Dehgam end, no fault event

recorded but it is confirmed from GETCO that the Disturbance

Recorder data was received at Asoj end. It seems that RECO

file is being transferred DR data to evaluation stations (Asoj) by

default.

GETCO representative informed that as file is received at Asoj, it must be available at Dehgam as well and the same might have not been retrieved at Dehgam local PC. POWERGRID may contact Shri Pancholi, EE GETCO for any clarification.

b. Event logger: In Event Logger print out of above tripping only

main CB status recorded. The status of other events like Main-

1&2 protection Start/Trip, A/R operation, Carrier sent etc were

not recorded.


Proper analysis of tripping could not be carried out in absence of

DR & EL printouts.

GETCO representative informed that they will look in to the matter.

SA8.6: Rectification of Bus Bar Protection Scheme at 400kV Nagda MPPTCL

S/S

POWERGRID has informed that four numbers new 400kV PGCIL bays

(Bina – Nagda – Dehgam) are likely to be commissioned in the month

of April 2007 at 400kV Nagda S/S. As such up-gradation of Bus-bar

protection scheme at 400kV Nagda S/S is essential for secured grid

operation.

MPPTCL representative informed that procurement process of new Bus Bar Scheme suitable for 13No. feeders at Nagda is already under process and correct status will be intimated shortly.

SA 8.7: Frequent mal-operation of protection at Gandhar

POWERGRID representative informed that 400kV Jhanor – Dehgam ckt-I has tripped on 09.01.07 and 09.03.07 at Jhanor NTPC end only and Auto re-closed successfully, for the fault in 400kV Dehgam – Soja line. At Dehgam end, no tripping and relay indications were observed in both instances. To avoid undesirable tripping of healthy line, matter has to be investigated & rectified.

NTPC representative informed that they are in the process of procurement of Numerical Relays to replace the existing ABB make RAZFE relays for Main-I protection of both 400kV Jhanor – Dehgam # 1 and 400kV Jhanor – Dehgam # 2 at their end.

ITEM NO. 9: Date and Venue of the next meeting. The next meeting is proposed during June/July 2007 wherein system

disturbances during the period 01-01-2007 to 31-03-2007 will be discussed.

Exact date and venue will be communicated separately.


ANNEX-I

LIST OF PARTICIPANTS

96th Protection Committee Meeting held on 29th & 30th March, 2007 at Vadodara hosted by GETCO

CSEB ( Chhatisgarh State Electricity Board ) Shri D.K. Chawda Executive Engineer (T&C), Raipur GETCO (Gujarat Energy Transmission Corporation Limited) Shri M.K. Mehta Addl. Chief Engineer (Testing), Baroda Shri B.R. Panchal Superintending Engineer (Testing), Baroda Shri J.N. Pancholi Executive Engineer (Testing), Asoj Shri B.K. Rakholia Executive Engineer (Testing), Gotri Shri J.S. Shah Dy. Engineer (Testing), Baroda Shri S.R. Charan Dy. Engineer (Testing), Gotri Shri R.P. Satani Dy. Engineer (Testing), Asoj Shri N.M. Sheth Dy. Engineer (Testing), Baroda Shri A.M. Athavale Junior Engineer (Testing), Asoj GSECL (Gujarat State Electricity Corporation Limited)

Shri U.D. Adhvaryu Superintending Engineer (Testing), Baroda MSETCL (Maharashtra State Electricity Transmission Company Limited)

Shri C.G. Barbole Chief Engineer (LD), SLDC, Kalwa Shri R.N. Tonge Superintending Engineer (TCC), Vashi Smt. R.R. Bhide Superintending Engineer (TCC), Pune Shri B.H. Gujarathi Executive Engineer (LD), SLDC, Kalwa Shri P.S. Ingle Dy. Executive Engineer (TCC), Pune Shri J.G. Nandapurkar Dy. Executive Engineer (TCC), Nagpur Miss V.B. Sawant Jr. Engineer, (TCC), Vashi MPPTCL (Madhya Pradesh Power Transmission Corporation Limited)

Shri V. Mehto Superintending Engineer (T&C), Bhopal MPPGCL (Madhya Pradesh Power Generation Corporation Limited)


Shri Naresh Punjabi Executive Engineer (T&C), Jabalpur NTPC (National Thermal Power Corporation)

Shri T.K. Rao Dy. General Manager (EM), KSTPS, Korba Shri S. Kumar Sr. Supdt. (O&M/EM), JGPS, Jhanor NPCIL (Nuclear Power Corporation of India Limited) Shri A.N. Thakur S.M.E.(E), TAPS 3 & 4, Tarapur Shri S.V. Shivalkar S.M.E.(E), TAPS 1 & 2, Tarapur Shri Mahesh P. Karia SO/D (EMU) TAPS 3 & 4, Tarapur Shri N.S. Patil Sr. Engineer (Elect.), KAPS, Kakrapar PGCIL (Power Grid Corporation of India Limited)

Shri D. Bruhananda Sr. Engineer (O&M), WRTS, Nagpur TPC (Tata Power Company)

Shri M.V. Kini Sr. Manager (ET&A), Trombay, Mumbai TPL (Torrent Power Limited)

Shri D.V. Dave Asstt. Manager (Elect.), Ahmedabad REL (Reliance Energy Limited)

Shri A.M. Waknis Addl. Manager (Trans.), R/S Goregaon, Mumbai WRPC (Western Regional Power Committee) Shri S. D. Taksande Superintending Engineer (P) Shri B. R. Joshi Executive Engineer (P)


ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Sl. No.

NAME OF S/S

DATE OUT AT

NAME OF THE LINE/ICT

SYSTEM DATE/ CHARGED AT

REASON

3.01

400kV Khandwa

01.10.06 11:09

400kV Khandwa-Dhule # 2

POWERGRID 18:43 A/T due to operation of line reactor PRV protection at Dhule end which was tested and no abnormality observed. Suspected due to DC earth leakage at Dhule

3.02

400kV Padghe

01.10.06 22:23

400kV Tarapur-Padghe #1, #2

POWERGRID 23:03 #1 23:29 #2

A/T on transient B phase to E/F. Heavy wind prevailed at the tripping time. A/R selector switch kept in Non-Auto mode at Tarapur end.

3.03

400kV Padghe

02.10.06 07:58

400kV Tarapur-Padghe #1

POWERGRID 12:55

A/T due to operation of O/V stage-I protection at Padghe. A/R selector switch kept in Non-Auto mode at Tarapur end.

3.04

220kV TAPS

03.10.06 12:54

220kV TAPS- Borivali

MSETCL 13:23 A/T at both ends on C-ph to E/F.

3.05

400kV Padghe

03.10.06 02:41

400kV Tarapur-Padghe #1

POWERGRID 09:16

A/T due to operation of O/V stage-I protection at Padghe. A/R selector switch kept in Non-Auto mode at Tarapur end.

3.06

400kV Mapusa

04.10.06 17:01

400kV Kolhapur-Mapusa #1

POWERGRID 11.10.06 12:11

A/T due to operation of O/V stage-I protection at Kolhapur MSETCL end. D/T received at Mapusa end A/R lockout took place due to three phase tripping.

3.07

220kV KAPS

04.10.06 17:58

220kV KAPP- Vav # 1

GETCO 18:51 A/T at both ends on C-ph to E/F.

3.08

400kV Satpur

05.10.06

400kV Sarni-

MPPGCL 13:33 A/T at both ends on distance protection


a 11:50 Indira Sagar

scheme.

3.09

400kV Raipur

05.10.06 17:52

400kV Korba- Raipur # 2

POWERGRID 18:35 A/T on transient B phase to E/F.

3.10

400kV Khandwa

09.10.06 14:04

400kV Khandwa – Dhule # 2

POWERGRID 15:01 A/T at Khandwa end only while transferring the line on TBC. Three phase tripping occurred and hence A/R did’nt take place.

3.11

400kV Bhadra-vati

11.10.06 14:48

400kV Bhilai - Bhadravati

POWERGRID 14:59 A/t due to mal-operation of PLCC channel –I at B’vati end which was identified & rectified. A/R lockout due to three phase tripping.

3.12

400kV Mapusa

11.10.06 17:03


POWERGRID 18.10.06 10:05


3.13

400kV Itarsi

13.10.06 15:54

400kV Jabalpur- Itarsi # 4

POWERGRID 17:56 A/T due to mal-operation of CSR (Controlled Shunt Reactor) protection at Itarsi. Matter taken up with M/s BHEL for investigating the tripping and remedial measure.

3.14

220kV TAPS

14.10.06 11:35


MSETCL 11:54 A/T at both ends on B-ph to E/F.

3.15

220kV TAPS

14.10.06 11:48

220kV TAPS- Boisar


3.16

220kV TAPS

14.10.06 12:11

220kV TAPS- Boisar


3.17

220kV Vav

14.10.06 13:25

220kV Vav – Ukai (Th)

GETCO 13:50 A/T on aided trip at Vav end. Heavy spark & damage at B-ph CT clamp at Ukai end.

3.18

220kV TAPS

17.10.06 12:27

220kV TAPS- Boisar


3.1 220kV 21.10. 220kV MSETCL 12:01 A/T at both ends on C-ph


9 TAPS 06 11:37

TAPS- Borivali

to E/F.

3.20

400kV Jabalpur

23.10.06 20:47

400kV V’chal- Jabalpur # 3

POWERGRID 21:22 A/T on transient B phase to E/F. Line A/R at Jabalpur end only.

3.21

220kV TAPS

26.10.06 12:37


MSETCL 27.10.06 15:47

A/T at both ends on C-ph to E/F.

3.22

400kV Indore

28.10.06 06:03

400kV Indore- Asoj # 2

POWERGRID 08:40 A/T due to mal-operation of NGR Buchholz relay protection at Indore due to suspected leakage DC system. D/T command sent to Asoj end.

3.23

400kV Mapusa

29.10.06 05:04


POWERGRID 18.10.06 10:05


3.24

400kV Asoj

03.11.06 06:05

400kV Asoj- Amreli

GETCO 06:15 A/T on transient Y phase to E/F. Line A/R at Asoj end. No cause found in patrolling.

3.25

400kV Koradi

06.11.06 07:58

400kV Koradi- Bhusaval # 2

MSETCL 08:05 A/T at Koradi end only on L/O trip for remote end fault. Spurious D/T command received through NSD61 Prot. Coupler causing unwanted tripping at Koradi end. Protection Coupler counter advanced at Koradi end without corresponding advancement at Bhusawal end. D/T trials taken later but nothing abnormal found. Matter is under further investigation.

3.26

220kV Haldarva

07.11.06 16:28

220kV H’rva – Kawas # 1

POWERGRID 08.11.06 15:23

A/T on R- ph to E/F. R-ph string flashed at Loc. No. 174(S).

3.27

400kV Asoj

10.11.06 11:15

400kV Asoj- SSP

GETCO 11:42 A/T due to system voltage high.

3.28

220kV Haldarva

01.12.06 06:50

220kV H’rva – Kawas # 2

POWERGRID 07:25 A/T on B- ph to E/F. Patrolling done by PGCIL. No cause found.

3.29

400kV Nagda

04.12.06 02:55

400kV Nagda- Indira Sagar

MPPGCL 03:50 A/T due to system high voltage.

3.30

400kV Satna

13.12.06 10:45

400kV Satna- Bina # 1

POWERGRID 10:51 A/T due to DC leakage at Bina. D/T received at Satna.


3.31

400kV Satna

13.12.06 10:57

400kV Satna- Bina # 1

POWERGRID 11:01 A/T due to DC leakage at Bina. D/T received at Satna.

3.32

400kV Chandra-pur

14.12.06 16:25

400kV C’pur- Parli # 1

MSETCL 15.12.06 14:35

A/T at both ends on A-N fault. Phase conductor alongwith insulator string came down at Location No. 189.

3.33

220kV Haldarva

19.12.06 15:00

220kV H’rva – KAPP #1

POWERGRID 16:10 A/T on B- ph to E/F. Patrolling done by PGCIL. No cause found.

3.34

400kV Sipat

19.12.06 20:03

400kV Sipat- Raipur # 3

POWERGRID 20:03 A/T on transient A-ph to E/F. A/R successful at both ends.

3.35

400kV Satna

22.12.06 16:50

400kV V’chal- Satna # 4

POWERGRID 17:46 A/T on operation of O/V protection due to DC leakage at V’chal NTPC end. D/T signal received at Satna.

3.36

400kV Satna

29.12.06 15:28

400kV V’chal- Satna # 4

POWERGRID 18:05 A/T on receipt of D/T signal from V’chal NTPC end.

Baart sarkar Government of India kond`Iya ivaVut … at Padghe S/S. The distance relay of 220kV Wada...

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