f-3, midc area, andheri (east), mumbai - 400 093 durbaaya fo@sa · 2007-11-13 · the tower...

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]

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ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸— Sub :- Minutes of 98th Protection Committee Meeting held on 23rd & 24th October 2007 at Raipur. Ÿ¸−¸½™¡¸ / Sir,

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Please find enclosed herewith the minutes of 98th Protection Committee Meeting of Western Regional Power Committee, Mumbai held on 23rd & 24th October 2007 at Chhattisgarh State Electricity Board, Raipur for your information and necessary action.

¤¸¾“ˆÅ ˆÅ¸ ˆÅ¸¡¸Ä¨¸¼î¸ œ¸®¸½¢¨¸¬¸¢Ÿ¸¢÷¸ ˆÅú ¨¸½¤¸¬¸¸ƒ’ www.wrpc.nic.in œ¸£ ž¸ú „œ¸¥¸¤š¸ í¾ — Minutes are also available at WRPCommittee website www.wrpc.nic.in

š¸›¡¸¨¸¸™ /Thanking you

ž¸¨¸™ú¡¸/Yours faithfully,

(‡¬¸.”ú.’¸ˆÅ¬¸¸¿”½/S.D. Taksande) ‚š¸ú. ‚¹ž¸.(£.)/Suptdg. Engr.(P.) ¬¸¿¥¸Š›¸ /Encl. :- „œ¸£¸½Æ÷¸¸›¸º¬¸¸£ /As above

http://www.wrpc.nic.in/


MINUTES OF THE 98th PROTECTION COMMITTEE MEETING

The 98th Protection Committee Meeting was held on 23rd & 24th October 2007 at

Raipur, Chhatisgarh. The list of participants is placed at Annex -I.

Shri Manoj Dey, Member (T&D), CSEB welcomed the members and participants

to the 98th meeting of Protection Committee. He said that it was a great pleasure for

CSEB to host the meeting at Raipur and hoped that the meeting will be successful in

arriving at important decisions in protection related issues.

Inaugurating the meeting, Shri Rajib Ranjan, Chairman, CSEB/WRPC stated that

the Protection Committee is one of the important forums of WRPC, where the grid

occurrences are analysed in detail and continuous improvement in protection system and

devices is discussed. Laying stress on the importance of adopting the rules and

regulations pertaining to system protection by all the utilities in the Western Region, he

said that in the area of power transmission, system protection has an important role and in

its absence one cannot think of continuous supply of quality power. He requested all the

power utility members in WR to strictly follow the system protection regulations in order

to manage the whole system effectively in the ensuing Rabi season when the demand in

the region will be in increasing mode.

Shri P. Patel, Member Secretary, on behalf of WRPC welcomed all the members and

participants to the 98th Protection Committee Meeting and thanked Shri Rajib Ranjan,

Chairman, CSEB/WRPC and other dignitaries from CSEB for their presence on the occasion in

spite of their busy schedule and also for having consented to host the meeting by CSEB at

Raipur. He stated that apart from the recommendations of the inquiry Committee on the two

partial grid disturbances on 25th & 28th February 2007, there are total ten important occurrences

reported by the constituents for this meeting covering occurrences between April and June

2007. These occurrences will be discussed, analysed and remedial measures to be evolved to

avoid recurrence. He wished for fruitful discussions during the two days meet. He then

requested Shri S. D.Taksande, Superintending Engineer (Protection), WRPC to take up Agenda

items for discussion.

Minutes of 98th WRPC PCM

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

the members and participants to the 98th Protection Committee Meeting. He once again

thanked Shri S.N. Chauhan, Chief Engineer (T&C), CSEB and his team of dedicated

engineers for the excellent arrangements made for the meeting and comfortable stay of

the participants. He requested protection engineers to keep operational all protection

schemes in their jurisdiction so as to avoid/minimize the disturbances in the region. He

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 97th Protection Committee Meeting.

Superintending Engineer (Protection), WRPC, stated that minutes of 97th Protection

Committee Meeting of WRPC held on 17th & 18th July 2007 at REL, Mumbai were

circulated vide WRPC letter no. Prot./97-PCM/2007-08/WRPC/7149 dated 2nd August

2007. Shri P. Barik, SO/F, EMU, KAPS vide his email dated 11.09.07 has desired to

incorporate following corrections in the minutes:

1. ITEM 2.04: In the MOM it was mentioned that “CTs of ABB make are replaced with

BHEL make at Haldarwa end” but the same were replaced at KAPS switchyard for

220kV KAPS- Haldarwa feeders.

2. In the participants list, name of Shri P. Barik, SO/F, EMU, KAPS, NPCIL, who

attended the meeting, did not appear by mistake and the same may be included in the

relevant list.

With the above modifications, the minutes for 97th Protection Committee Meeting were confirmed.

Item No.2: System disturbances

2.01: Grid Disturbances in Western Regional Grid on 25.2.2007 at 1634 hours and

28.2.2007 at 13:11 hours:

Central Electricity Authority had constituted an inquiry Committee under Section 73(l) of

Electricity Act, 2003 to inquire into the above incidences of grid disturbances of

25.02.2007 & 28.02.2007 under the chairmanship of Shri Santosh Kumar, Member


(GO&D), CEA, New Delhi. Report of the Committee has been submitted and accepted

by the Central Electricity Authority, New Delhi. Full report of the Committee is available on

the website of WRPC (viz. www.wrpc.nic.in). Recommendations pertaining to Protection have

also been circulated to members, vide letter No.WRPC/Prot/GD FEB 07/2007-08/699 dated 7

Sept. 2007 and were discussed for implementation during the meeting. The fallout of discussions

and present status on the recommendations is enclosed at Annexure 2.01.

2.02: System disturbance at 400 kV Bhopal S/S in MPPTCL system on 01-04-2007:

At 04:01hrs on 01.04.2007, 220kV Bhopal-Bairagarh feeder No.2, connected to Bus-2,

tripped from both ends with failure of 220kV CT (System Control make) installed on R Ph.

of the feeder at 400kV Bhopal S/S. The Bus Bar Protection operated and resulted in

tripping of all the feeders on Bus No.2, since Bairagarh feeder was connected on Bus-2.

Oil from the R Ph. CT splashed, on the adjacent 220kV Bhopal-Bairagarh-1 feeder bay and

hence the 220kV Bhopal-Bairagarh-1 feeder tripped from both ends. The Tie CB

connecting 220kV Bus-1 & 2 tripped successfully. There was no interruption to any area

due to above trippings.

Normalcy was restored between 04:38 to 04:48hrs.

Committee observed that operation of Bus bar protection of Bus No.2 due to

bursting of 220kV Bhopal-Bairagarh R ph CT is in order. Committee recommended

regular tan δ test on CTs. As the C.T. was only 14years old, regular tan δ

monitoring could have avoided its failure.

2.03: System disturbance at 220 kV Vapi S/S in GETCO system on 04-04-2007:

On 04.04.2007 at 11:55Hrs, there was a persistent fault on 220kV Vapi-KAPP line-1, but

the line did not trip on distance and backup protection. The fault was cleared by all the

feeder tripping from S/S end and or far end. The auxiliary relay 75E (center relay of 5

relay unit of EE make) of Bus PT selection relay found inoperative due to its burnt coil.

The 75E relay extends the DC supply to protection relays and tripping circuit, hence the

DC supply to protection relays and tripping circuit in 220kV Vapi-KAPP line-1 was not

available. Relay operations of 220kV Ambheta, Ambheti , KAPS-2 lines and DR of DPR



of far end of Ambheti line indicate conversion of initial C phase fault into multiphase

fault either in 220kV Vapi-KAPP line-1 or 220kV Vapi-KAPP line-2 OR in both the

lines. The 220kV TAPS line tripped from S/S end on Zone-3 Reverse (EE make SHPM

101). As per report of M/s PGCIL, heavy fire in the farm was observed at the bottom of

the tower location No.8 (Tension location). The three 100MVA 220/66 kV transformers

did not trip at both ends.

The burnt coil of 75E relay of Bus PT selection relay was replaced. The DPR was tested

& found OK. One extra LED, for trip circuit supervision is provided on the panel in

addition to the existing annunciation.

All the feeders were restored between 12:10Hrs and 17:15Hrs.

Committee suggested for separate D.C. supply to Main and Back up protections.

Tripping of TAPS feeder on reverse zone-3 is in order.

GETCO informed that LBB protection is now provided.

2.04: System disturbance at 400 kV Lonikand S/S in MSETCL system on 09-04-2007:

On 09.04.2007 at 05:30Hrs, the ‘R’ ph C.T. of 220kV transfer bus coupler got burst. The

220kV Sanaswadi-I line was connected to Main Bus-I through TBC. The Bus Bar

protection operated and all the lines and ICT-I & ICT-III connected to this bus tripped on

B.B. protection. The 400/220kV, 315MVA ICT-II connected to Main bus-II tripped due

to over loading. The Bus Bar protection operation, due to bursting of CT is in order.

Normalcy was restored at 06:40Hrs on 09.04.07.

Committee suggested reduction in the periodicity of tan delta testing of old CTs so

that proper track of change in tan delta can be maintained for monitoring the health

of CT

Committee felt that operation of bus bar protection and selective tripping of lines

was in order.

2.05: System disturbance at 400 kV Bableshwar S/S in MSETCL system on 24-04-2007:

On 24.04.2007 at 15:25Hrs, 220kV LBB protection operated at 400kV Bableshwar S/S


due to delay in tripping of circuit breaker of 220kV Bableshwar – Walunj ckt II. There

was transient fault of B phase to earth on 220kV Bableshwar – Walunj ckt II and 220kV

Bableshwar – Bhenda line simultaneously resulting in tripping of these lines at both ends

on distance protection. As the 220kV Bableshwar – Walunj ckt II was connected to

220kV Main Bus –II, all equipments connected to this bus tripped.

The two 400/220kV ICTs, 220kV Bus Coupler and 220kV tripped feeders were restored

between 15:52Hrs and 18:10Hrs on 24.04.07 except 220kV Bableshwar – Walunj ckt II

which was taken in to service at 02:03Hrs on 25.04.07.

MSETCL representative informed that on checking of circuit breaker of Walunj ckt

No. II at 400kV Bableshwar S/S, its closing & tripping time of all the three phases

was in order i.e. closing time around 84msec and tripping time around 20msec. Also

LBB relay timer & pick up was found satisfactory for the settings of 200ms for

timer, 0.8A for each R & B ph and 0.2A for E/F. Therefore committee suggested for

slightly increasing the 0.2A E/F current setting to avoid spurious tripping.

MSETCL to counter above problem has decided to change L.B.B. relay

configuration from 2 O/C + 1 E/F to 3 O/C configuration as per earlier

recommendation of WRPC.

2.06: System disturbance at 400 kV Indore S/S in MPPTCL system on 30-04-2007:

On 30.04.07 at 16:10hrs, Y Phase tension string between gantry to gantry of 220kV

Badnagar feeder, flashed over and the jumper fell over 220kV Main Bus-I & II resulting

in Bus fault at 400kV Indore S/S. The 220kV sides of 400/220kV, 315MVA ICTs-I, II &

III tripped on Y ph O/C & 400kV side tripped on inter-trip. 220kV Indore –South Zone-I

& 220kV Indore –South Zone-II tripped from 220kV South Zone S/S on O/C. 400kV

Indore-Itarsi feeder tripped at 400kV Itarsi S/S and 400kV Indore-Nagda feeder tripped at

400kV Nagda S/S.

Backfeed availed at 220kV South Zone at 16:25hrs, and other 132kV S/S’s from 16:40hrs

to 17:10hrs. After isolating Y ph jumper of Badnagar feeder, 220kV Bus charged at

17:58hrs and system was normalized thereafter.


Committee requested for further analyzing as to why 400kV Itarsi and Nagda

feeders tripped from other end. Also O/C setting of transformers needs to be

rechecked. Committee observed that the occurrence took place due to maintenance

aspect of the S/S and suggested for improving the preventive maintenance of

important EHV Sub station at Indore. Thermo vision survey and physical

inspection of ageing insulator strings may be increased till they are replaced.

2.07: System disturbance at 220 kV Nagda S/S in MPPTCL system on 06-05-2007:

On 06.05.2007 at 16:02Hrs spare Earth wire snapped on 400KV Main Bus-I connected

with canopy of 315MVA T/F-III gantry column, resulting the 400kV bus fault & causing

tripping of 400kV Nagda-Indore feeder from both ends, 400kV Nagda –ISP feeder from

ISP end & 400kV Nagda-SSP-I feeder from SSP end. At the time of tripping Nagda -

SSP feeder II was in OFF condition. The 3 x 315MVA T/F did not trip, hence the same

were hand tripped. At 16:55hrs. Nagda-ISP charged from 400kV Nagda end, but tripped

again. At 17:08hrs. Nagda-Indore charged from 400kV Nagda end, but tripped again.

All other lines restored between 16:58hrs and 17:25hrs.

Committee suggested MPPTCL to further study all the trippings related to above

occurrence for coherency of sequence.

2.08: System disturbance at 220 kV Vapi S/S in GETCO system on 06-05-2007:

On 06.05.2007 at 17:05Hrs, the 220kV B-Ph PT of 220kV Bus A got burst & caught fire.

220kV Ambheta and KAPP line-1 tripped on DPR from Vapi end & all other feeders

tripped from remote end. All the T/F and BC were hand tripped. The Vapi S/S was in

dark from 17:05 to 17:55hrs. The EE make CAG11 type B/B protection scheme with

connected CTR 600/1A with stabilizing resistance of 345 Ohm, is in service at this S/S.

The busbar protection check zone relay operated but main Zone-A relay did not operate,

hence the busbar protection did not operate and all the lines tripped from Vapi end/

remote end. The DP schemes of 220kV Ambetha and KAPP-I might have operated due

MM3V type of electro-magnetic DPR, which can mal-operate on reverse closure fault.


The disturbance report on 220kV Vapi-Ambheti line at 400KV Ambheti end and 220kV

Ambheta and KAPP-I at Vapi end indicates that the fault persisted for 350 msec.

The CAG 11 scheme tested & found in order, and the matter is referred to M/s AREVA.

All the feeders are having CT ratio of 600/1A. It is proposed to replace the CT’s with

CT’s having CT ratio of 1200/1A, to avoid CT saturation.

All the feeders were restored between 17:55Hrs and 18:1Hrs.

GETCO informed that as check zone relay operated but main Zone-A relay did not

operate for CAG Bus Bar protection, they have referred the matter to M/s AREVA.

As an interim measure, the current setting of the relay has been reduced from 0.8A

to 0.3A by increasing stabilizing resistor to increase sensitivity of the relay.

Committee suggested for looking in to possibility of tripping Bus coupler on reverse

zone setting as back up to Bus bar protection after 200msec. Tripping of Bus

Coupler on reverse zone setting should not trigger LBB and for which special care is

required to be taken.

2.09: System disturbance at 400 kV Bina S/S in MPPTCL system on 20-05-2007:

At 15:55hrs on 20/05/07, 400kV Bina-Bhopal-2 tripped from Bhopal end on A ph to

earth fault in Zone-I. At 400kV Bina S/S, Main-II protection relay operated for the fault

in 400kV Bina-Bhopal-2 but tripping command continue for more than 0.2Sec (LBB

timer setting), resulting into initiation of tripping through LBB relay. Operation of LBB

relay at Bina S/S resulted in tripping of 400kV MPPTCL – PGCIL interconnector I & II,

400kV Bina – Bhopal ckt-I and 315MVA 400/220/33kV ICT Nos. I, II and III. After the

occurrence took place, breaker and relay were tested and found working satisfactorily,

however, self resetting type tripping relay was found sticky which was attended and

rectified.

All the lines & T/F charged between 16:55hrs to 18:26hrs. No interruption to any area

Committee observed that same trip relay was used for Main-I and Main-II relays

when the standard practice followed is to use separate trip relay for each Main-I


and Main-II right from separate D.C. supply. Committee recommended to adopt

two separate trip relays for Main-I and Main-II.

2.10: System disturbance at 220 kV Haldarva S/S in GETCO system on 10-06-2007:

At 14:20hrs, 220kV Haldarva-IPCL line-2, tripped from both ends on Zone-I with B & C

Ph. fault. Simultaneously, Bus-Bar differential protection relay Zone-A, B Ph operated

and all the feeders and transformers connected to 220kV Bus-A, tripped on 96-Bus Bar

protection relay. Due to tripping of 220/66kV, 100MVA T/F No.-I, other 220/66kv

50MVA T/F No.-II tripped from LV side on O/C (R Ph.), due to overload. On inspection

after the occurrence the B ph CB isolator (29C) clamp towards CB side was found

damaged, B ph jumper between CB isolator & CB found overheated inside the clamp and

burnt grass found in the nearby area of the isolator of the 220kV IPCL line-2, connected

to Bus Bar-A. The Bus-A & Bus-B are operated in isolated mode to reduce fault level.

No fault was found on 220kV IPCL line-2, during patrolling. Damaged components in

the bay of 220kV IPCL-2 were replaced. Knee point voltage of all the CT’s of 220kV

IPCL line-2 were measured & found normal. Bus Differential protection relay was tested

and the results were found O.K. The scheme as whole was found normal.

Bus-A was charged through 220kV Jhagadia line at 17:25hrs, and all the lines & feeders

were restored between 14:45hrs to 18:57hrs, except 220kV IPCL line-2 which was

charged at 17:15hrs on 11.06.2007.

Committee opined that Bus bar protection might have operated due to damages to

isolator clamp and fire in vicinity. GEB informed that the setting of relay increased

from 244V to 340V, considering the present fault level of 27KA at 220kV Bus.

2.11: System disturbance at 220 kV Talangpore S/S in GETCO system on 21-06-2007:

At 06:45 hrs, in the bay of 220/66kV T/F No.I, flashover took place on the Y ph insulator

string (suspension) located on flyover conductor at top gantry and got detached from top

gantry and it remained swinging on the clamp of the flyover conductor, but did not touch

the ground. Though this being a bus zone-A fault, the Bus Bar protection scheme (Type:


RADSS, ABB make) did not operate and all the lines connected to 220kV Talanpore S/S

tripped from remote end, except T/F-I, T/F-II, T/F-III and Bus Coupler. The T/F-I, II &

III were hand tripped at Talangpore S/S. 220kV Bus Coupler CB did not trip. The

flashover insulator string and damaged clamp of P.I. was replaced. The T/F-I was tested

for routine tests & the results were satisfactory. The Bus Bar scheme was logically

checked and found healthy. The matter has been referred to the supplier for non -

operation of the scheme during fault.

The Bus A & B were charged taking 220kV Vav line into service at 08:10hrs. All the

lines & T/F charged by 19:40hrs.

Committee felt that high resistance fault might have resulted in to low fault current

which was not sufficient to operate the differential relay may be the reason for non –

operation of RADSS bus bar scheme. Matter may be referred to supplier M/s ABB

for thorough testing.

ITEM NO. 3: Tripping of lines / ICTs:

The incidences of tripping of lines and ICTs during the period 01-04-2007 to30-06-

2007 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. Inquiry Committee to inquire into incidences of grid

disturbances of 25.02.2007 & 28.02.2007 has recommended that the monthly status

on the healthiness of DRs (with time stamping status) and the sequential event

logging devices at each of the sub-stations/generating station is checked and

certified by the concerned substation/generating stations in-charge, and confirmed

to RPC secretariat.

Superintending Engineer (Protection), WRPC informed the committee that

D/R and SER status will hence forth be monitored every month by WRPC in


WRPC OCC meetings. A format supplied by OCC forum of WRPC was

circulated to constituents as a reference.

Committee once again emphasized that SERs and DRs along-with GPS time

synchronisation are essentially to be provided on priority at all 400kV S/Ss

first, and then, at all important 220kV S/Ss, for proper analysis of the events

during disturbance and for taking required preventive measures.

ITEM NO.5: Follow up points:

5.01: Provision of Numerical Distance Protection on 400kV Bhadravati –

Chandrapur ckt I & II

During 89th PCM of WREB, while reviewing information on A/R, DR and SER in

Western Region, POWERGRID stated that DR has been provided at Bhadravati on

400kV Bhadravati –Chandrapur ckt I & II and they felt that these are being short

lines DR provided at POWERGRID S/S Bhadravati is sufficient for analyzing the

tripping of these lines. However, committee felt that DRs should be provided for

both ends even for short lines and the same is essential for analyzing the event of

tripping. Accordingly, POWERGRID during 93rd PCM agreed to provide

Disturbance Recorder at Chandrapur on 400kV Bhadravati – Chandrapur ckt I&II

by replacing old Main-I & Main-II (P-40) relays with numerical relays, however,

replacement of relays yet not materialized. In this connection MSETCL requested

PowerGrid for providing new relays at Chandrapur S/S.

Powergrid representative intimated that REL make numerical relays have

already been procured and the same will be commissioned at Chandrapur

within one month.

5.02: Re-commissioning of Bus Bar Protection Schemes at 400kV

Sub-station Indore:

Chief Engineer (LD), SLDC, MPPTCL, Jabalpur vide his letter No. 07-05/955 dt


20.07.2007 has intimated that 400kV and also 220kV Bus Bar Protection

Schemes at 400kV Sub-station, Indore in MPPTCL, which were out since long,

have been taken in to circuit after thorough testing and checking at 16:40Hrs on

26th June 2007 and 20:00Hrs on 30th June respectively. Also, 400kV 50MVAR

Reactor which was taken out from 400kV Sarni-Indore line after LILO of the

same at ISP, has been utilized in view of the high voltage problem and taken into

service on 400kV Indore – ISP ckt-II at 18:22Hrs on 29th June 2007.

Committee noted.

5.03: Commissioning of PLCC system in 220 KV lines of SEBs emanating

from Powergrid Khandwa S/S:

MPPTCL representative stated that 400kV Khandwa (PGCIL) Sub-station is

having 4 Nos. 220kV feeders namely 220kV Nepa-I, 220kV Nepa-II, 220kV

Barwaha with tapping at Omkareshwar and 220kV Julwaniya. All the feeders

have been installed and commissioned with carrier added protection except for

220kV Khandwa – Julwania. This is due to the fact that this feeder is proposed to

be 220kV Omkareshwar – Julwania, for which Carrier cabinet with protection

couplers have already been provided by NHDC, Omkareshwar.

Committee noted and suggested MPPTCL to check for the matching

protection couplers at Khandwa, Omkareshwar and Julwania as feeder

220kV Khandwa–Julwania will become 220kV Khandwa-Omkareshwar

and 220kV Omkareshwar– Julwania after LILO at Omkareshwar.

5.04: Procurement of new Busbar protection scheme at 400 KV Nagda MPPTCL S/S:

Commissioning activities of PowerGrid four nos. new bays (Bina – Nagda –

Dehgam) at Nagda are in full swing. During 97th PCM, M/s MPPTCL

representative intimated that tender for procurement of new Bus bar protection

scheme at Nagda is finalised and the same is expected from the firm within two

months.


MPPTCL representative intimated that supply order for procurement of new

busbar protection scheme at Nagda has been placed on M/s ABB and its

delivery is expected within two months.

ITEM NO. 6: Other grid points:

6.01: 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 had agreed 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 was 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 referred

to manufacture BHEL for indicating the suitability of the prime mover for

the auto re-closure duty.

In this connection NPCIL have informed that the matter is under review

by BHEL and BHEL have requested NPCIL for details of A/R scheme at

Trombay or Chandrapur and scheme proposed to be adopted for 400kV

lines emanating from TAPP-3 & 4, including the reclosure times. M/s

BHEL also desired to know the kind of electrical disturbances expected on

the system as after effects of auto re-closure of lines; to enable them study

their effects on TG system.

(i) Committee discussed the issue and suggested to furnish auto re-

closure details of schemes adopted at Chandrapur, Trombay

and in NTPC stations to NPCIL for furnishing the same to M/S

BHEL.


(ii) As regards to information asked by M/S BHEL i.e. kind of

electrical disturbance expected on the system as a after effects of

auto re-closure of lines, the committee requested NPCIL to

request M/S BHEL to be more specific as to what they want so

that it could be discussed in PCM forum.

6.02: Repair / replacement of Main–I protection P-40 relays of Powergrid

lines at Sarni:

MPPTCL vide their SLDC’s letter No. 07-05/RPC-37A/1233 dtd 10.09.07

have informed that the power supply module of M/s EE make P-40 relays

used as Main-I since 1987 in the line protection schemes of both 400kV

PowerGrid lines namely Sarni – Itarsi line and Sarni– Koradi line at Satpura

400kV S/S are giving problem and are presently out since 22:30Hrs of

01.09.07. Chief Manager, PGCIL, 400kV Sub-station, Pathrota, Itarsi was

requested for repairing / replacement of P-40 relays /Main – I Protection

system of both the lines at the earliest.

PowerGrid representative informed that the relay has been commissioned

on 15.09.2007.

6.03: REL interconnection at MSETCL 220kV Boisar sub-station:

The interconnection of REL and MSETCL through LILO of 220kV Dahanu

– Versova ckt # 1 at Boisar S/S of MSETCL was completed on 01.07.2007.

In the 97th PCM, committee observed that Mumbai islanding scheme is

reviewed by the enquiry committee set up to investigate the partial grid

disturbance on 25.02.07 and 28.02.07. As such the setting of UF relays on

REL-MSETCL interconnection should also be in line with the

recommendation of the enquiry committee. REL agreed to do the needful

after receipt of enquiry committee report. Committee further suggested for

a meeting between MSETCL and REL to co-ordinate the relay settings at

Boisar, Versova and Dahanu S/Ss. Accordingly, a meeting was convened

between MSETCL & REL at 220kV Boisar S/S on 24.07.2007 to discuss


REL – MSETCL Boisar interconnection related issue.

Committee noted the above. MSETCL and REL representatives

informed that all issues have been sorted out and a co-ordination team

is formed to look into all related matters.

6.04: Avoidable tripping of 220kV PGCIL Kumhari – Bhilai-3 feeder on 24.08.07:

Superintending Engineer (T&C), CSEB, Bhilai requested PGCIL that the

Zone-III timings of 220kV PGCIL Kumhari – Bhilai-3 feeder be revised to

800ms from the existing settings of even less than 700ms in order to avoid

undesired tripping of this particular line.

PGCIL representative informed that the Zone-III setting of 220kV

PGCIL Kumhari – Bhilai-3 feeder has been revised as desired.

6.05: Wrong system operation on 400kV Bhilai – Seoni line on 19.09.2007:

Superintending Engineer (T&C), CSEB, Bhilai informed that on 19.09.2007

at 11:26Hrs, 400kV Bhilai – Seoni line was charged from Seoni end

(425kV) instead of Bhilai end (412kV) resulting in operation of Reactor

backup protection at 400kV S/s Bhilai. The line should have been charged

from Bhilai end first and synchronized from Seoni end. 400kV Bhilai sub-

station is an important S/S in WR grid and any wrong operation in or

around the S/S may trigger in minor or major grid disturbance.

Committee observed that standard practice of charging a line is from

lower voltage end. As regards to lines emanating from Generating S/S,

line should be charged from other end so as not to pass on any

disturbance to P.S. while charging. This is to be followed irrespective of

voltage being low at P.S. end.

ITEM NO. 7: Retrofitting / replacement of old Protection Schemes / equipments by

Powergrid:

POWERGRID, vide their letter No. WRTS/O&M/R/141/ 2202 Dated 26.09.2007

proposed retrofitting of old protection schemes, replacement of obsolete


Protection & PLCC system, replacement of obsolete ABCBs and replacement of

Gapped LAs with Gapless LAs at their various sub stations. Copy of their letter

was a part of Agenda of the minutes for discussion by the utilities. On further

query by WRPC about the matter, PowerGrid representative informed that

Consent of Beneficiaries is required for filing of petition for additional

capitalization on account of these works. They have also intimated that whenever

new equipment / system replaces the old equipment / system, the original value of

the equipment / system will be deducted from the gross block.

Committee discussed the technical aspects of the proposal. It was observed

that the proposal was in line with the protection philosophy discussed in

various meetings of Protection Committee and in the interest of secure and

stable grid operation. The committee therefore recommended acceptance of

the proposal.

ITEM NO. 8: Any other item:

8.01: Use of numerical distance protection reverse zone as back up to busbar

protection:

With the permission of the Chair, MSETCL, T&C circle Aurangabad representative

put up a proposal for use of numerical distance protection reverse zone as back up

to busbar protection for discussion before the WRPC protection committee and

requested for WRPC protection committee’s opinion in this regard. MSETCL

representative further stated that this scheme is under consideration for

implementation in MSETCL system.

Committee members participated in the discussion during the presentation of

the scheme by MSETCL. Due to complexities in relay co-ordination, members

desired that the scheme be circulated along with minutes of 98th WRPC PCM

so that it can be studied in detail by individual constituents and further

discussion can take place in the next PCM for its consideration for use. Note

on the scheme is placed as Annexure-8.


8.02: Review of Mumbai islanding scheme:

Superintending Engineer (Protection), WRPC informed that in pursuance of

recommendation of the Inquiry Committee on Grid Disturbance of 25th & 28Th

February, 2007, a meeting was held on 18th September 2007 to review the readiness

of implementation of revised Mumbai Islanding Scheme. TPC were to adopt new

Governor setting on Hydro M/Cs as per revised frequency settings. TPC and REL

both expressed readiness in all respects within a fortnight time. It was decided that

the scheme will be implemented in a mutually agreed date.

ITEM NO. 9: Date and Venue of the next meeting.

The next meeting is proposed during December 2007 end wherein system

disturbances during the period 01-07-2007 to 30-09-2007 will be discussed. Exact

date and venue will be communicated separately.


ANNEXURE-3

TRIPPINGS OF LINES / ICTS

Sl. No.

NAME OF S/S

DATE OUT AT

NAME OF THE LINE/ICT

SYSTEM / Provision of A/R (Yes/No)

DATE/ CHARGED AT

REASON

3.01

400kV Padghe

03.04.07 13:10

200MVA, 220/100kV ICT No.II

MSETCL

??? The ICT tripped on Diff.Protn. & Buccolz. B Ph. HV bushing of the ICT was found damaged.

3.02

220kV KAPS

04.04.07 11:54

220kV KAPP- Vapi # 1 & # 2

POWERGRID

12:48 A/T on distance protection due to C-ph to E/F.

3.03

220kV KAPS

04.04.07 13:29

220kV KAPP- Haldarwa # 1

POWERGRID


3.04

220kV KAPS

04.04.07 14:45

220kV KAPP- Haldarwa # 2

POWERGRID


3.05

400kV Koradi

05.04.07 19:20

400kV Bhusawal -2

MSETCL (Y) 05.04.07

19:52 Line tripped for transient R-N fault. A/R at both end operated but went into L/O because of recurrence of fault in reclaim time

3.06

400kV Nagda

06.04.07 15:35

400kV Nagda-SSP-I

MPPTCL (Y)

16:30 O/V & Main-1 & 2 optd. A/R L/O

3.07

400kV Nagda

07.04.07 14:25

400kV Nagda-SSP-I

MPPTCL (Y)

15:15 --

3.08

400kV Chandra-pur

07.04.07 19:20

400kV C’pur -Bhadravati ckt-4, 3 & 1

POWERGRID (Y) 20:27 Ckt.3 & 4 tripped

simultaneously on transient B-N fault due to snapping of earth wire of 400kV Bhadrawati-Ramagundam ckt. near Bhadrawati end. Ckt-1 tripped at Chandrapur end only probably due to mal operation of P40 Main 1


protection. 3.09

400kV Nagda

08.04.07 14:46

400kV Nagda-SSP-I

MPPTCL (Y)

14:46 A/R successfully at both ends.

3.10

400kV Nagda

11.04.07 10:50

400kV Nagda-Indore

MPPTCL (Y)

11:25 Main-I &II ( B ph Z1N) Operated..

3.11

400kV Satpura

18.04.07 20:30

400kV Bhilai- Sarni

MPPGCL (Y)

23:08 A/T at both ends due to operation of Buchholz relay of Line Reactor at Bhilai end.

3.12

400kV Nagda

21.04.07 06:34

400kV Nagda-ISP

MPPTCL (Y)

07:22 A/T due to O/V & Main-2 protection operated.

3.13

400kV Nagda

21.04.07 06:34

400kV Nagda-SSP-I

MPPTCL (Y)

14:25 A/T due to O/V & Main-1 protection Operated. A/R L/O

3.14

400kV Nagda

21.4.07 07:30

400kV Nagda-SSP-II

MPPTCL (Y)

08:25 A/T due to O/V & Main-1 protection Operated. A/R L/O

3.15

400kV Nagda

21.04.07 10:25

400kV Nagda-SSP-II

MPPTCL (Y)

30.04.07 24:00

A/T due to O/V & Main-1 protection Operated. A/R L/O

3.16

400kV VSTPS

25.4.07 14:17

400kV V’chal- Satna # 1

POWERGRID (Y)

???? A/T due to persistence of transient B-ph to ground fault after A/R cycle.

3.17

400kV Bhilai

29.04.07 01:48

400kV Bhilai- KSTPS # 1

POWERGRID (Y)

03:02 A/T at both ends on R-N fault.

3.18

400kV Nagda

30.04.07 16:10

400kV Nagda-Indore

MPPTCL (Y)

16:30 Main-2 (B ph Z3) Operated. A/R L/O

3.19

400kV Asoj

02.05.07 15:42

400kV Asoj – Ukai

GETCO (Y)

15:42 A/T at both ends on R-N fault. A/R successful at both ends.

3.20

400kV Koradi

04.05.07 13:31

400kV Koradi-Chandrapur

MSETCL (Y) 13:31 Transient B-N fault. A/R

successful at both ends.

3.21

220kV KAPS

06.05.07 17:07

220kV KAPP- Vapi # 1

POWERGRID

19:44 A/T at remote end Vapi only due to B-ph to E/F.

3.22

220kV KAPS

06.05.07 17:07


POWERGRID

19:38 A/T at in Zone-2 at KAPS and CB manually tripped at remote end Vapi due to C-ph to E/F.


3.23

400kV Itarsi

07.05.07 16:12

400kV Itarsi- Indore # 2

POWERGRID (Y)

08.05.07 04:40

A/T on persisting Y-N fault due to snapping of E/W between Loc. No. 324-325.

3.24

400kV Indore

07.05.07 17:48

400kV Indore- Asoj # 2

POWERGRID (Y)

08.05.07 04:55 (07.05.07 20:40GETCO)

A/T on R-N fault due to snapping of E/W at Loc. No. 765 near Asoj. A/R lockout due to persisting nature of fault.

3.25

400kV Bhilai

08.05.07 14:45

400kV Bhilai- Korba # 1

POWERGRID (Y)

15:13 A/T from both ends due to Y-N fault in Zone-I from Bhilai end. Main CB of the feeder was out and D/T received from other end leading to A/R lockout.

3.26

400kV Raipur

09.05.07 01:27

400kV Raipur- Rourkela # 1

POWERGRID (Y)

16:56 A/T from both ends due to ph–ph fault at 403.3km from Raipur end Also the REF of line Reactor at Raipur end operated due to NGR LA failure causing three phase tripping. B-ph jumper had snapped and fell over R-ph conductor at Location No. 1100.

3.27

400kV Vapi

09.05.07 09:27

400kV Gandhar- Vapi

POWERGRID (Y)

???? A/T on Y- ph to E/F. A/R operated successfully in main and tie bay Y-pole but due to repetitive fault in Y-ph, all three poles of main and Tie CB tripped

3.28

400kV Chandra-pur

09.05.07 09:55

400kV C’pur-Parli # 3

MSETCL (Y) 10.05.07

09:20 A/T on B-N fault. The fumes & flames due to burning of the sugarcane waste had created the fault between Loc.No.557 & 558.

3.29

400kV Jabalpur

10.05.07 17:31

400kV J’pur – Itarsi # 1 & 2

POWERGRID (Y)

17:37 # 2 17:56 # 1

A/T on R-ph to E/F. After A/R, second fault occurred. Patrolling was carried out from loc. 113 to 177, no abnormality was found in the section patrolled, rain with thunderstorm was reported in the area at the time of tripping.

3.30

400kV 11.05.07

400kV Raipur

POWERGRID (Y)

17:12 A/T from both ends due to Y N fault at 343 7km from


0 Raipur 7 15:48

Raipur- Rourkela # 1

Y-N fault at 343.7km from Raipur. A/R attempted but line again tripped due to reappearance of fault after 4 seconds.

3.31

400kV Raipur

11.05.07 15:48

400kV Raipur- Rourkela # 2

POWERGRID (Y)

15:54 A/T at Rourkela end only due to mal-operation of Main-2 protection for Rourkela feeder-2 at Rourkela for a Y-N fault of Rourkela –1 feeder.

3.32

400kV V’chal

14.05.07 15:43

400kV V’Chal-Jabalpur-2

POWERGRID (Y)

16:20 Carrier received in both the channels at Jabalpur due to which Main-I & Main-II protn. Operated at both ends, during patrolling no abnormality was observed.

3.33

400kV Raipur

15.05.07 12:23

400kV Raipur-Sipat

POWERGRID (Y)

13:14 A/T from both ends on Y Phase to earth fault A/R took place and gone for A/R lockout due to persisting fault.

3.34

400kV Chandra-pur

15.05.07 22:50

400/220kV, 315 MVA ICT-2

MSETCL

16.05.07 00:36

Tripped because of shorting of the trip terminals of WT meter of C ph unit at TB in control box, due to seepage of oil through control cable.

3.35

400kV Asoj

18.05.07 15:05

400kV Asoj – Ukai

GETCO (Y)

15:05 A/T at both ends on R-N fault. A/R successful at both ends.

3.36

400kV Jabalpur

19.05.07 15:00

400kV Itarsi-2

POWERGRID (Y)

19.05.07 15:15

Tripped from both ends on B-Ph to E/F. Just after A/R second fault occurred. During patrolling no abnormality was observed.

3.37

400kV Asoj

23.05.07 17:58

400kV Kasor – SSP

GETCO (Y)

18:28 A/T on B ph to E/F. Patrolling carried out, no cause found.

3.38

400kV Asoj

25.05.07 17:38

400kV Asoj- Amreli

GETCO (Y)

???? A/R operated and then lockout.

3.39

400kV Kolhapur

25.05.07 17:22

400kV Mapusa-1

POWERGRID (Y)

17:56 Due to receipt of direct trip. Suspected transient fault at Kolhapur end or mal operation of PLCC. Event


loggers & PLCC at Mapusa & Kolhapur end are being checked

3.40

400kV Indore

28.05.07 16:36

400kV Asoj-2

POWERGRID (Y)

28.05.07 17:04

Transient B Ph.-E fault, A/R successful at Asoj end only.

3.41

400kV Jabalpur

28.05.07 20:18

400kV Itarsi-3

POWERGRID (Y)

A/R successful at both ends, on transient R Ph –E Fault. No abnormality found during patrolling.

3.42

400kV Jabalpur

31.05.07 09:31

400kV Itarsi-1

POWERGRID (Y)

31.05.07 21:02

Line Auto tripped on Y –E Fault. A/R attempt was taken but tripped again due to sensing of fault by Main-II. Trial taken from Itarsi end, but tripped immediately on 2 Ph. Indication of Main-II. No abnormality found during patrolling.

3.43

220kV TAPS

31.05.07 21:24

220kV TAPS- Borivali

MSETCL 22:58 A/T on transient R-N fault from both ends.

3.44

400kV TAPP

31.05.07 22:05

400kV Padghe-1

POWERGRID (Y)

31.05.07 23:23

A/T at both ends due to A ph to E/F.

3.45

400kV Chandra-pur

01.06.07 14:40

400kV C’pur- Parli # 3

MSETCL (Y)

14:40 A/T on transient B-N fault and successfully A/R at both ends.

3.46

400kV Asoj

02.06.07

400kV Asoj- Wanakbori

GETCO (Y)

04:57 At Asoj M-2 prot-P-40 & ph selector operated and at Wanakbori M-2 prot-P-40 operated. Y-ph 400kV CT of middle and line BKR of Unit No.-4 & ICT failed. P-40 mal-operated.

3.47

400kV Chandra-pur

04.06.07 16:15


MSETCL (Y)

16:35 A/T on transient B-N fault.

3.48

400kV Itarsi

05.06.07 15:11

400kV Itarsi- Indore # 2

POWERGRID (Y)

06.06.07 03:37

A/T on permanent B-N fault due to failure of mid span joint of earth wire.

3.49

400kV Chandra-pur

06.06.07 17:20


MSETCL (Y)

17:55 A/T on transient R-N fault.


3.50

400kV Chandra-pur

06.06.07 18:39


MSETCL (Y)


3.51

400kV Chandra-pur

06.06.07 20:02

400kV C’pur- B’vati # 4

POWERGRID (Y)

20:02 A/T on transient R-N fault and successfully A/R at both ends.

3.52

400kV Koradi

09.06.07 17:05

3x100MVA,400/220kV ICT-I

MSETCL 23:04 T/F tripped on Differential protection due to bursting of 220kV side R ph LA.

3.53

400kV Raipur

09.06.07 20:56

400kV Raipur- Sipat # 3

POWERGRID (Y)

21:45 A/T on transient R-N fault at 74.33kM from Raipur end. A/R from both ends but again tripped on reappearance of fault after half second.

3.54

400kV Asoj

10.06.07 07:47

400kV Asoj – Ukai

GETCO (Y)

08:38 A/T at both ends on transient B ph to E/F. A/R L/O.

3.55

400kV Jabalpur

10.06.07 14:40

400kV V’chal- Jabalpur # 1

POWERGRID (Y)

15:33 A/T due to persistence of transient R-ph to ground fault after A/R cycle. Special patrolling carried out from Loc. 285 to 325 & 53 to 103, no abnormality was found.

3.56

400kV Jabalpur

10.06.07 14:41

400kV V’chal- Jabalpur # 2

POWERGRID (Y)

15:33 A/T on transient B-N fault. Special patrolling carried out from Loc. 285 to 325 & 53 to 103, no abnormality was found.

3.57

400kV Kasor

11.06.07 11:16

400kV Kasor- SSP

GETCO (Y)

11:34 A/T on transient B-N fault. A/R operated and then definite trip. No abnormality found during patrolling.

3.58

400kV Bhilai

13.06.07 17:40

400kV Korba- Bhilai # 1

POWERGRID (Y)

17:59 A/T from Bhilai end only on receipt of D/T signal in channel-2 As this problem recurred even after attempt for solution of problem by M/s ABB. The matter has been taken up with manufacturer


of PLCC panel M/s ABB Mumbai.

3.59

400kV Nagda

14.06.07 00:02

400kV Nagda-SSP-I

MPPTCL (Y)

14.06.07 06:35

A/T due to O/V

3.60

400kV Bhadravati

14.06.07 21:42

400kV B’wati- Chandrapur #3 & # 4

POWERGRID (Y)

22:44 #3 22:46 #4

Main CB & Tie CB tripped on B-N fault. Low air pressure alarm “CB healthy” of Main CB appeared & prevented A/R of Main CB & tripped on pole discrepancy. As main CB A/R unsuccessful, Tie CB could not get permissive command & Tie CB also tripped on pole discrepancy. Suggestion for improvement from site is that the scheme should be modified such that in case Main CB could not attempt the re-close command due to some problem like ‘Air pressure low’ alarm then permission to the Tie CB is cleared automatically so that the line can A/R through Tie CB.

3.61

220kV KAPS

15.06.07 17:40


POWERGRID

18:15 A/T at both ends due to C-ph to E/F.

3.62

400kV Jabalpur

18.06.07 16:54

400kV J’pur – Itarsi # 1

POWERGRID (Y)

17:24 A/T at both ends on R to B ph to ph fault. Special patrolling carried out from Loc. 571 to 648, no abnormality was found.

3.63

400kV Chandra-pur

19.06.07 08:23


MSETCL (Y)


3.64

400kV Bhilai

20.06.07 15:04


POWERGRID (Y)

15:34 A/T from both ends on R-N fault at 82% of the line length from Bhilai end. As Main CB was out of service & Tie CB in non-auto mode at Bhilai and D/T signal received at Bhilai end led to unsuccessful auto re-close. The matter has been taken up with M/s ABB, manufacturer of PLCC panel installed in this feeder for receipt of D/T signal.

3.65

400kV Asoj

20.06.07 18:35

400kV Asoj – Amreli

GETCO (Y)

21.06.07 14:41

A/T due to snapping of earth wire and falling on B-ph conductor at Loc. No. 463.

3.6 400kV 21.06.0 400kV MPPTCL 21.06.07 ARLO, C/LO


6 Nagda 7 06:57

Nagda-Indore

(Y) 07:25

3.67

400kV Nagda

21.06.07 06:57

400kV Nagda-ISP

MPPTCL (Y)

21.06.07 08:10

A/T due to O/V

3.68

400kV Nagda

21.06.07 06:57

400kV Nagda-SSP-II

MPPTCL (Y)

21.06.07 14:30

A/T due to O/V

3.69

400kV Nagda

21.06.07 18:08

400kV Nagda-SSP-II

MPPTCL (Y)

26.06.07 13:30

M-1, M-2 Protn. Operated. ARLO.

3.70

400kV Kasor

23.06.07 03:31

400kV Kasor- Chorania

GETCO (Y)

Not charged due to high system voltage

A/T due to high system voltage

3.71

220kV TAPS

25.06.07 06:12


MSETCL 06:38 A/T at both ends due to A ph to E/F.

3.72

220kV TAPS

25.06.07 10:33


MSETCL 26.06.07 12:52

A/T at both ends due to A ph to E/F.

3.73

400kV Kasor

25.06.07 12:18

400kV Kasor- Chorania

GETCO (Y)

12:43 A/T due to high system voltage

3.74

400kV Bhilai

25.06.07 18:55


POWERGRID (Y)

19:35 A/T on R-N fault at 48Km from Bhilai end. After dead time of 1sec it got successfully A/R at Bhilai end but A/R unsuccessful at Korba end, may be due to low air pressure.

3.75

400kV Nagda

26.06.07 07:00

400kV Nagda-Indore

MPPTCL (Y)

26.06.07 07:25

A/T due to O/V

3.76

400kV Nagda

26.06.07 07:00

400kV Nagda-ISP

MPPTCL (Y)

26.06.07 07:45

A/T due to O/V

3.77

400kV Nagda

26.06.07 07:00

400kV Nagda-SSP-I

MPPTCL (Y)

Still out A/T due to O/V

3.78

400kV Kasor

26.06.07 07:02

400kV Kasor – SSP

GETCO (Y)

07:28 A/T due to high system voltage


3.79

400kV VSTPS

27.06.07 11:50

400kV V’chal- Korba # 2

POWERGRID (Y)

???? A/T on B-N fault. Immediately after re-closing, line again tripped due to persisting fault.

3.80

400kV Kasor

27.06.07 14:19

400kV Kasor- GPEC

GETCO (Y)

14:50 A/T from both ends on B-N fault.

3.81

400kV Nagda

29.06.07 13:04

400kV Nagda-ISP

MPPTCL (Y)

29.06.07 13:25

A/T due to O/V

3.82

400kV Boisar

29.06.07 13:05

400kV Tarapur- Padghe # 1

POWERGRID (Y)

14:14 A/T due to operation of O/V stage-2 protection at Padghe end.

3.83

400kV Nagda

29.06.07 13:04

400kV Nagda-SSP-II

MPPTCL (Y)

29.06.07 14:00

A/T due to O/V

3.84

400kV Koradi

29.06.07 19:05

400kV Koradi- Bhusawal # 2

MSETCL (Y)

19:05 A/T on transient B-N fault and successfully A/R at both ends.

3.85

400kV Raipur

30.06.07 03:11

400kV Korba- Raipur # 2

POWERGRID (Y)

02.07.07 16:55

A/T from both ends. Due to prev-ailing high system voltage, O/V stage –I operated at Raipur end, resulting in 3 ph tripping of line. System voltage before tripping was approximately 433kV. Line could not be taken in to service before 02.07.07 due to higher system voltage.


Protection Division, WRPC, Mumbai

Subject: Draft Minutes of 98th Protection Committee Meeting

Please find enclosed herewith Draft Minutes for the 98th Protection

Committee Meeting held on 23rd & 24th Oct. 2007 in CSEB at Raipur.

Submitted for approval please.

(B.R. Joshi)

E.E.(P)

S.E.(P)

M.S. please


f-3, midc area, andheri (east), mumbai - 400 093 durbaaya fo@sa · 2007-11-13 · the tower...

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