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LIST 1) Chief Engineer (LD), MSETCL, Kalwa.Fax-27601769/65 2) Chief Engr. (Trans O&M), MSETCL, Bandra. Fax No. 022 26598587. 3) S.E. (T&C), MSETCL, Aurangabad Fax-0240-2234220 /2346290 4) S.E (T&C), MSETCL, Pune. Fax-9520-2617532/2612342 5) S.E. (T&C), MSETCL, Nagpur. Fax-95712-2234220 6) S.E.(T&C), MSETCL, Nasik Road Fax-0253-2462422 7) S.E.(T&C), MSETCL, Vashi Fax--022-27662055 8) S.E.(Gen.Tstg), MSPGCL,Eklahre, Nasik Fax-95253-2810496/2810499 9) S.E. (Task Force), MSPGCL, Nagpur Fax- 0712-2591717. 10) Chief Engineer (Gen), GSECL, H.O. Baroda. Fax-0265-5512129/2344537 11) Addl. C.E.(Testing), GETCO, Baroda. Fax-0265-2351218 12) Chief Engineer(LD), MPPTCL, Jabalpur. Fax-0761- 2664343 /2282632. 13) E.D. (T&C),MPPTCL, Jabalpur. Fax-0761-2661696 14) Addl.C.E., MPPGCL, Jabalpur Fax- 0761-2660063/2665805 15) E.E. (SLDC), MPPTCL, Indore Fax-0731-2874515 16) Chief Engineer (LD), CSPTCL, Bhilai. Fax-0788-2282632/0788-383633 17) C.E. (T&C), CSEB, Raipur.Fax-0771-4066988/07759-226227 18) EE (T) , CSPGCL- Fax.No. 07789-226227 19) S.E.(T&C), CSPTCL, Bhilai. Fax.No.- 20) S.E.(T&C), CSPTCL, Raipur. Fax No.0771-4066988. 21) E.E.(T&C), CSPTCL, Bhilai. Fax No. -0788 2281561 22) EE, Division VIII(MRT),Elect. Dept; Goa Fax 0832-2735124. 23) Supdt.Engr., Electricity Dept., DNH, Silvasa. Fax : 0260-2642338 24) Executive Engr., Electricity Dept. DD. Fax : 0260-2250889 25) D.G.M.(O.S. ),N.T.P.C., Mumbai, Fax- 28216692 26) D.G.M.(EM), KSTPS,NTPC,KorbaFax 07759-233088/ 232440 27) DGM (EMD), VSTPS, NTPC, Vindhyachal Fax-07805-247713 28) DGM (EM-I),NTPC, SIPAT Fax-07752-246506/246691. 29) AGM(O&M), KGPP,Adityanagar, Surat Fax 0261-2861428/2861433 30) Sr.Supdt. (EM),Gandhar, NTPC Fax-02642-87402 / 87450 31) DGM (O.S.), WRLDC, Mumbai Fax-28235434 32) DGM, WRTS-I POWERGRID,Nagpur.Fax-95712-641366/2641496 33) Addl General Manager, WRTS-II,POWERGRID,Baroda Fax-0265-2480952 34) SME (E), TAPS-3&4,Tarapur Fax 02525-282001/282073 35) Maintenance Superintendant,TAPS –1 & 2,Tarapur.Fax- 02525-282121 36) SME(E), NPCIL ,Kakrapara Fax 02626-234266 37) GM(Maint.). T.Power., Ahmedabad.Fax-079-27506679 38) AGM (ET&A),TPC, Trombay. Fax –022-66687088 39) Dy.Gen. Manager,Dahanu TPS Fax- 952528-222576 40) Vice President, Reliance Energy, Mumbai Fax-30094488 41) GM (Electrical), JPL, Raigarh. Fax.No.7767-281995,281993. 42) Director (G M Division), CEA, New Delhi. Fax.No.011-26109750 43) AGM(OS), NSPCL, New Delhi . Fax.No.011 26717363/26717366 44) GM, KSK Mahanadi Power Co Ltd., Hyderabad- Fax.No.04023559930 45) Director (Tech & Projects), JSW Energy( Ratnagiri) Ltd., Fax.No. 022 67848393 46) GM, RGPPL,Anjanwel,Guhagar,Ratnagiri. Fax.No. 02359 241071

1 Minutes of 115th Protection Committee of WRPC

MINUTE OF 115th PROTECTION COMMITTEE MEETING OF WRPC HELD ON

6/7.09.2012 AT PUNE

The 115th Protection Committee Meeting of WRPC was held on 6/7.09.2012 at Pune. The list

of participants is placed at Annexure -I.

Shri A. V. Kolap, S.E.TR.(O&M), MSETCL, Pune welcomed all the members and

participants attending the meeting. Shri S. G. Kelkar, ED(Opn), MSETCL welcomed all the

members and participants and highlighted the progress of MSETCL at glance.

Shri S. D. Taksande, Member Secretary (I/C), WRPC, welcomed all the members and the

participants of the 115th Protection sub-Committee Meeting. He stated that todays meeting in

past 30th & 31st July occurrence. A committee headed by Chairperson CEA studied the

occurrences and submitted its report covering recommendations having a special time line.

Many recommendations are protection related and therefore implementation of these

recommendation in the time bound manner is the responsibility of PCM group. Also

Chairman WRPC & CMD MSETCL during the meeting held at WRPC Mumbai on 7th

Aug.2012 formulated a group consisting of Shri U.G.Zalte Chairman TCC & Dir(O)

MSETCL, Shri S D Taksande MS WRPC, & Shri P Pentayya GM WRLDC to review

defence mechanism , RGMO facility, Black start facility and communication facility in WR

so that W Region remain safe during any eventualities. In this regard special meeting was

arranged on 07.09.2012 at same venue. He requested all the participants to actively

participate in discussions.

He also informed that a presentation by CPRI B,lore on protection audit has been

arranged during the course of meeting. He thanked MSETCL for making nice arrangements

for stay and transport of the participants.

Member Secretary (I/C) then requested Shri M. M. Dhakate, SE(Protection), WRPC to take

the agenda items for discussion in seriatim.

The agenda Items were taken up for discussions.

ITEM NO.1: CONFIRMATION OF MINUTES OF 114TH PROTECTION

COMMITTEE MEETING.

SE(Protection), WRPC stated that the minutes of 114th PCM, held on 11/12.06.2012 at

WRPC Mumbai, were circulated vide WRPC letter No. Prot./114 PCM/2012/WRPC-6410


dated 27th June 2012 and following correction/observations have been received :

1. Rinfra vide email dated 26.07.2012 have requested to add following sentence in

ITEM NO. 6.3 : Revised islanding scheme in R-infra Mumbai transmission network

of 114th PCM :

“Committee has opined that R-Infra can proceed in implementing the Revised

Scheme as presented during the meeting.”

2. Item No. 2.4(ii) Multiple tripping of 400 KV lines at 400 kV JSWEL, Jaigad

(Ratnagiri) sub-station on 17.03.2011: It is noted and confirmed by WRLDC/JSWEL

that these trippings were occurred on 17.03.2012.

Members agreed for above modification/corrections.

The minutes of 114th Protection Committee were confirmed with above modifications.

ITEM NO.2: SYSTEM DISTURBANCES

2.1: System disturbances in CSPTCL/CSPGCL system.

2.1 (i) Occurrence at Korba East (Extn) (DSPM) Station on 1.05.2012

CSPGCL representative explained the disturbance as below:

At 10:34 Hrs on 1.05.2012, cascaded tripping of following lines, ICTs and generators

occured :

Kotmikala-Amarkantak-1 Ph to Ph fault, DPR operated

Kotmikala-Amarkantak-2 Over current

400/220 kV ICT at Korba(W) R & Y phase Overcurrent

Korba(E) Unit-3,4,5 (50 MW each) Overspeed/turbine trip

BALCO Unit-1 &2 Over frequency

DSPM unit-1 & 2(250 & 210 MW) Gen. elect. & reheater protection

220 kV Korba(E)-Mopka B-G fault, DPR operated

220 kV BALCO-Korba(E)-1&2 Alongwith generators at BALCO

220 kV DSPM-Banari S/c and 220 kV DSPM-Suhela S/c were already out of service due to

falling of tower. Also, 220 kV Korba(E)-Raigarh, 220 kV Korba(E)-Budhipadar-II & III


were kept out to control overloading on 220 kV DSPM-Korba(E) S/c.

Approximately, 940 MW loss of generation without any load loss has been reported.

In the 114th PCM during discussion on Item No. 2.1(i) : System disturbance at 400 kV Korba

system in CSPTCL system on 19-04-11, Committee recommended that in the absence of

SPS, the over current setting of the lines in the area can be raised to 150% so that sufficient

time margin would be available to take corrective actions in the event of loss of line in the

area thereby avoiding overloading the other lines by cutting-off the load or backing down the

generation. Committee further suggested that WRLDC would device SPS in consultation

with CSPGCL/CSPTCL on urgent basis.

WRLDC intimated that SPS is very much essential in Korba area, since the area is generation

hub (with evacuation mostly on 220kV system) and the transmission system is fragile around

Korba area. Tripping/planned outages of the two to three 220kV transmission elements in

this corridor causes overloading and tripping of other elements in this corridor leading to

further depletion of the transmission corridor as in the above incidence. Proper line outage

coordination is also required for avoiding such incidence till the SPS is put in place.

Committee opined that the recommendation of 114th PCM as mentioned above may be

implemented at the earliest. It is also felt that inview of complex network in

Chhattisgarh , a small group could be formed to finalize the SPS scheme and be put up

to PCM.

2.1 (ii) Occurrence at Sipat on 15.06.12 and 19.06.12

NTPC representative explained the occurrence as below :

On 15.06.2012 and 19.06.2012 at NTPC Sipat there was a grid disturbance resulting in a total loss of

generation of the order of 2100-2300 MW at Sipat.

A group comprising of representatives from WRPC, WRLDC, POWERGRID and NTPC met at

NTPC-Sipat on 29.06.2012 to analyze the events that led to the disturbance and suggest remedial

measures to prevent recurrence of the same. A report analyzing the grid disturbance at Sipat STPS on

15.06.2012 and 19.06.2012 is available on WRPC website.

Brief descriptions of occurrences as explained by NTPC Sipat representative is given below:

Incident on 15.06.2012 at NTPC Sipat:


On 15.06.2012 at 1832 hrs at NTPC-Sipat units # 1,2,4,5 were on bar generating 2347MW. At

18:34:51 hrs B Phase of 400kV tie CT of IBT1 (400/132 kV) to ICT1 (765/400 kV) at Bay 14 at

NTPC Sipat burst and led to the tripping of IBT1 and ICT1 on Tee Differential protection. During the

explosion one broken insulator piece flew and damaged moose conductor clamp of LA of

IBT2(400/132 kV). This caused the conductor to snap and resulted in tripping of IBT2 on transformer

differential protection at 18:34:53hrs.

The Explosion of B phase CT of 14CT-B and splashing of hot oil caused following damages:

a. B phase CT of 14CT-B failed and completely damaged.

b. R & Y phase CT of 14CT-B and Y Phase CT of 14CT-A insulator got damaged.

c. 7 nos. Isolator stacks of Bay 13, 14 & 15 got damaged.

d. B-phase Circuit Breaker pole of 1452 breaker damaged beyond repair.

e. 1 no. IPS to twin Moose connector damaged in R-phase of IBT-2.

Approx. 20 meters of length of all 240 nos of control and power cables running in the main trench in

the vicinity of failed CT caught fire due to spillage of oil from CT and got damaged. These damaged

cables pertain to bay No 13 (IBT #1 main bay), 14 IBT#1 & ICT # 1 tie bay), 15 (ICT # 1 main bay),

16 (Raipur # 2 main bay), 17 Raipur # 2 and Ranchi # 1 tie bay) & 18 (Ranchi #1 main bay).

The tripping of the IBTs resulted in loss of station auxiliaries supply and the running units at Sipat

tripped as follows:

1) The Unit 2 tripped on low vacuum at 1836 hrs.

2) Unit 1 tripped at 1853 hrs, unit 4 at 1900 hrs and unit 5 at 1933 hrs.

The generation loss was around 2347 MW. The NTPC Sipat Engineers and staff quickly acted and

controlled the fire. Due to the above disturbance 400 kV Sipat-Raipur ckt 2 tripped at 18:40:44 hrs

and 400 kV Sipat-Ranchi tripped at 18:37:33 hrs. Further the tripping also led to high voltage in 765

kV and 400 kV networks and following elements tripped on High voltage.

1) 765 kV Seoni-Wardha 2 at 1900 hrs

2) 400 kV Seoni-Bhilai at 1853 hrs

3) 400 kV Seoni-Khandwa 1 at 1853 hrs

4) 400 kV Seoni-Bina at 1853 hrs

5) 400 kV Seoni-Khandwa 2 at 1900 hrs

6) 400 kV Seoni-Satpura at 1900 hrs

7) 765 kV Seoni-Bilaspur 1 at 1910 hrs

Restoration activities were taken up by Sipat and on 16.06.2012 by 1200 hrs around 2000 MW

generation was on bar. The ICT2(765/400 kV) and IBT2(400/132 kV) were charged. ICT1 and IBT1


remained out. While cable restoration work was in progress, another incident took place on

19.06.2012.

Incident on 19.06.2012 at NTPC Sipat:

On 19.06.2012 at 1615 hrs at NTPC-Sipat units # 1,2,3,4,5 were on bar generating 2150MW. At

16.16 Hrs on 19.06.2012 IBT-2 got tripped, which was the only source in service for 132KV

switchyard and in turn all station transformers got dead. On inspection it was found that LBB of 1552

(IBT-1) breaker operated leading to actuation of Bus Bar protection of 400 KV Bus-1. 400Kv Bus-1

became dead. All Bus #1 breaker 952, 1252, 2052 and 2452 got tripped. 400KV Bus-II was live

through Raipur # 1, Ranchi #2 and ICT#2. As IBT # 2 was charged from Bus#1 Main CB 1252 and its

dia i.e bay 10 & 11 were not commissioned, tripping of Bus #1 caused tripping of IBT #2.

This caused tripping of all running units at Sipat as follows:

Unit -2 at Sipat tripped immediately followed by tripping of unit-5 at 1623 hrs, unit- 4 at

1643 hrs and finally unit-1 at 1651 hrs. The generation loss was around 2150 MW and

resulted in high voltages in 765 and 400 kV networks.

Following lines tripped on high voltages.

1) 765 kV Sipat-Bilaspur 2 at 1653 hrs

2) 765 kV Seoni-Wardha 1 at 1653 hrs

3) 400 kV Raipur-Sipat 1 at 1653 hrs

4) 400 kV Seoni-Bina s/c at 1653 hrs

5) 400 kV Sipat-Ranchi 2 at 1653 hrs

6) 400 kV Bhilai-Seoni s/c at 1653 hrs

7) 400 kV Khandwa – Seoni 1 at 1653 hrs

8) 400 kV Seoni-Satpura at 1653 hrs

9) 400 kV Khandwa-Seoni 2 at 1653 hrs

There was no significant change in frequency due to incoming wind generation at that time. By 0230

hrs of 20.06.2012 all units at Sipat were synchronized.

The group recommended as following :

1) To explore the possibility of additional standby supply for auxiliaries from nearby 132 kV

system

2) The findings ( root cause analysis report of R & Y phase CTs by Areva).

3) New arrangement of sharing of shifting of loads between station and UATs


4) Procurement and replacement of the cables

Wrt recommendation No. 1 as above NTPC representative intimated that the matter is taken up with

Corporate office for providing 132 kV standby supply for auxiliaries as normally 33 kV standby

supply is provided.

Wrt recommendation No. 2 as above NTPC representative intimated that M/s Areva could not come

to any conclusion since the failed CT was completely damaged.DGA of 11CTs were done after the

incidence and six CTs which are Areva 2005 make and showing DGA violation were replaced. The

same will be taken back by M/s Areva for further checking and report is awaited. He further intimated

that tan delta of all 95 CTs have been carried out and the results are in order.

It was opined that the DGA oil samples in case of hermetically sealed CTs is a concern and the

frequency of carrying out the DGA analysis has to be restricted.

ED(O), MSETCL intimated that the CTs can easily be tested for tan delta, but even after showing

normal results, CTs including new CTs tend to fail. Hence DGA analysis is the only test to ascertain

the healthiness of the CTs

Wrt recommendation No. 3 as above NTPC representative intimated that

• IBT-2 Tie bay (Bay 10, 11) made ready and charged.

• Compressors control supply changed from Station board to Unit board in stage 1&2.

• Stage-2 compressor cooling water pump supply changed from station board to unit board.

• Replacement of 400KV damaged equipments completed.

• Repairing of damaged cables by 29.06.2012.

• Charging of all feeders by 11.07.2012.

Wrt recommendation No. 4 as above NTPC representative intimated that procurement and

replacement of cables is going on in opportunity outages.

Committee members discussed the matter and some additional recommendations were

suggested as below :

• The S/S layout should be such that the physical location of CT and cable trench

be at a distance to avoid fire in case of CT Bursting.

• FRS coating (even though costly) should be applied on entire length of control


cables so as to avoid propagation of fire and avoiding short circuiting of the

cable due to fire.

• Drain point leakage is required to be avoided.

• DGA analysis of all CTs to be done every three years.

• As new CTs are also failing and State agencies needs to procure any equipment

as per lowest bids. The procurement of inferior CTs can be avoided if stringent

specifications are given at the time of tendering. The specifications may be

firmed up/shared amongst the utilities.

2.2: System disturbances in GETCO/GSECL system.

2.2(i) Occurrence at Sachin S/s in Gujarat on 27.03.2012

GETCO representative explained the occurrence as follows:

At 00:05 hrs on 27.03.12 due to flashover of B-Phase PT of 220 kV Bus-B, bus fault

occurred leading to tripping of all feeders and ICTs at Sachin S/S on operation of Bus Bar

protection.

220 kV Sachin S/s is having double main and transfer bus switching scheme. The bus-

coupler was under planned shutdown for replacement of B-phase CT of 220 kV Bus-A.

GETCO representative further stated that the two bus arrangement was converted to single

bus arrangement through isolator, since the Bus Coupler was under outage.

Load loss of 204 MW was reported due to above without any generation loss.

Committee felt that Bus Bar operated correctly but healthiness of PT should be

monitored regularly.

2.2(ii) Occurrence at Kim S/s in Gujarat on 27.03.2012

At 14:15 hrs on 27.03.2012 GSEG-Mora-Kim and GSEG-Kim which were evacuation lines

for GSEG tripped on Y –phase distance protection. GSEG GT-1(52 MW) and GSEG

STG(52.1 MW) tripped due to loss of evacuation lines. Gujarat has reported that on

patrolling sugar cane wastes were found burnt below the locations 91 & 92. (distance 17.7

Km from Kim).


Committee felt that the tripping was in order. For the fault however more awareness

may be spread among farmers.

2.2(iii) Occurrence at Kakrapar APS on 4.05.2012

Rrepresentative from KAPS explained the occurrence as below:

On 4.05.2012 at 17:50 Hrs CB of Kakrapar-Haldarwa-2 at KAPS end tripped on pole

discrepancy protection with C10x relay flag while normalizing the line. NPCIL have

intimated that on investigation ‘B’ pole closing circuit anti pumping relay NC contact found

resistive. The same was attended through spare contact of anti pumping relay (52 yC) and

closing loop made healthy.

Committee felt that the tripping was in order.

2.2(iv) Occurrence at Nakhatrana S/s on 27.05.2012

Rrepresentative from GETCO explained the occurrence as below:

At 10:50 hrs on 25.05.2012 backup protection operated at 220 kV Nakhatrana-Nanikhakhar-

II leading to tripping of KLTPS and ALTPS units and subsequently Nakhatrana s/s

experienced zero power. Planned shutdown of 220kV Nakhatrana-Nanikhakhar-I was

availed at 25.05.2012 for earth wire replacement work. Panandro –Kukma-II was under

outage due to permanent fault from 24.05.12 for repairing broken conductor. Due to heavy

loading on Panandro –Kukma-I and heavy wind in reverse direction, the induction effect

made it very difficult and dangerous to work on Panandro –Kukma-II and hence Panandro –

Kukma-I was switched off at 10:50 hrs to enable to carry out work on Panandro –Kukma-II.

This led to tripping of Nakhatrana-Nanikhakhar-II on back up protection due to overload and

other lines also tripping of KLTPS unit 1 & 2(unit 3 &4 were under forced shutdown) and

ALTPS unit 1(unit-2 was under forced shutdown) due to lack of evacuation.

Committee discussed the matter and concluded that this incidence could have been

averted if proper outage coordination had been there.


2.2(v) Occurrence at Ichhapore S/s on 2.06.2012

Rrepresentative from GETCO explained the occurrence as below:

220 kV Kawas-Haldarwa-I & II lines were switched off for controlling line loading of 220

kV Kawas-Ichhapore line. Also, planned shutdown for 220 kV Navsari-Sachin line was

availed on 2.06.12. Load on Essar complex (200 MW), Sachin S/s(200 MW),

Ichhapore(70MW) was catered by 3 lines namely 220 kV Kawas-Ichhapore, 220 kV Vav-

Ichhapore and 220 kV Vav-Sachin. At 16:15 hrs on 2.06.2012 a direct trip command from

Kawas end received during PLCC testing carried out at Kawas 220 kV Kawas-Ichhapore

line. Tripping of Kawas-Ichhapore line led to overloading of 220kV other two lines and

eventually tripped on over current protection causing zero power at Ichhapore and Sachin s/s.

Load loss of 47 MW was reported during above incidence.

It was opined that there is plug system which has to be removed if any PLCC testing is to be

carried out for avoiding extension of direct trip command. The test plug might not have been

removed while carrying out the above test. GETCO representative stated that plug system is

available at Kawas end and same was not removed due to human error.

Committee felt that checklist for testing should be well documented and available at

each substation.

2.3: System disturbances in MPPTCL/MPPGCL system.

2.3(i) Occurrence at 220 kV Jabalpur S/S and Bargi HPS on 27.05.2012.

MPPTCL representative explained the occurrence as below :

On 27.05.2012 at around 21:45 hrs 132 kV B-Phase CT of bus-coupler bay at Bargi HPS got

burst which caused bus fault at Bargi. Bargi line -1 at Jabalpur tripped on zone -2 but due to

delayed opening of 132 kV breaker of Bargi-Jabalpur-II at 220 kV Jabalpur s/s, its “B”

phase pole got burst and created bus fault on 132 kV bus resulting into tripping three

transformers(220/132 kV) and all outgoing feeders from remote end including 45 MW Unit-

1. There was load loss of around 260 MW and generation loss at Bargi HPS at 31 MW.

Relay indications at Jabalpur 220 kV Jabalpur s/s - 132KV Bargi 1 – ABC G- Z2


132KV Bargi 2- C-N, Z3 3x40 MVA MTSB- DTOC-2 Trip both side 3x40MVA BHEL DTOC-2 Trip both side 1x160 MVA GEC- E/F 132 kV Marhotal s/s -Jabalpur - C ph. Z2, At 132 Narsinghpur S/s - On Shrinagar line- Forward Power Relay operated. MPPTCL representative intimated that the breaker was 23 year old BHEL make and failed

breaker was replaced on 31.05.12 with ABB make SF6 CB. He further intimated that SHPM

Quadramho Relay of 132 Bargi 2 feeder at Jabalpur Replaced on 16.06.12.

Committee felt that the tripping was in order. It was also felt that replacement of any

electrical equipment solely on age could not be recommended. The overall history of

equipment is to be considered before any replacement.

2.3(ii) Occurence at Satpura S/s on 5.04.2012

MPPGCL represtnative explained the occurrence as below :

On 5.04.2012 at 00:30 hrs at Satpura TPS, 220 kV main Bus-I PT ‘B’ phase (SCT make) got

burst. Consequently busbar differential zone-I(R&B) phase and zone –II(R phase) operated

resulting into tripping of all lines and generators connected on Bus-I and Bus-II. Generation

loss of 470 MW has been reported. In the instant incident “B” phase P.T. of Bus-I failed

very badly due to internal problem in PT and burst into pieces causing heavy splash of oil in

the surrounding area.

To avoid such recurrence the location of existing PTs of 220 kV Bus-I have been shifted.

The failed “B” phase P.T. was replaced with available SCT make P.T. in order to normalize/

charge 220KV Bus-I. However, these SCT make P.T.s are proposed to be replaced with

BHEL make P.Ts ordered recently by the site.

MPPGCL representative intimated that Westinghouse PTs which served for over 50 years

were replaced with SCT make PTs which are bursting quite often. Also, busbar protection

(Asia RADSS) again operated on 5.9.12 for which the detail report is not unavailable right

now.

MPPGCL was requested to submit the report.

Committee felt that the tripping was in order. It was also felt that replacement of any


electrical equipment solely on age could not be recommended. The overall history of

equipment is to be considered before any replacement.

2.3(iii) Occurrence at 132 kV Bina S/s on 4.05.2012


On 4.05.2012 at 07:45 hrs one tower of 132 kV Bina-Rajghat line at location no. 256

collapsed and 132 kV Bina-Rajghat tripped on DPR on AN phase and current fed was of the

order of 1592 A. Simultaneously 132 kV Bina-Chanderi line (which was on the same tower)

DPS operated on C-phase zone-I but A phase did not trip ( later CB trip coil found burnt).

After collapsing and tilting of the tower the fault came on A phase and started feeding current

approx 780 A in Chanderi feeder. Due to continuous feeding of fault current in A phase of

132 kV Chanderi feeder the 160MVA and 3x40 MVA transformers at Bina S/S tripped at on

E/F alongwith 132 kV Sagar, 132 kV Ashoknagar at Bina end on E/F. 132 kV Sironj and

Basoda feeders tripped from other end. Also, BORL 1&2 tripped from BORL end.

MPPTCL representative intimated that the breakers are MOCB type and over 35 years old.

The work of replacement of breakers is going on and already 90 % of these breakers have

been replaced.

ED(O), MSETCL intimated that many a places breakers were procured and installed as per

fault level at that time. But fault levels have changed a lot over the years and hence

CT/PT/Breakers needs to be upgraded as the fault levels are increasing.

Committee felt that the tripping was in order.

As regards to failure of new CT/PTs, Committee opined that the specifications

prepared at the time of procurement should be very stringent and also

warranty/guarantee for more than 5 years should be called for. Stage inspections

should be carried out strictly as per specifications.

2.3(iv) Occurrence at 220/132 kV Ujjain S/s on 7.05.2012


MPPTCL have intimated that on 7.05.2012 at 15:16 hrs 132 kV Ujjain-Ghosla line

attempted to trip on C phase zone –I indication at Ujjain end and tripped on over current E/F

from remote end. At Ujjain end B phase pole of MOCB got stuck up which continued to

feed heavy fault current and all the elements tripped from remote ends to stop feeding of

fault. Hence there was a total supply failure at 220 kV/132 kV Ujjain s/s. Ther is no bus bar

protection generally provided on 131 kV bus bar.

Later, the defective pole’s mechanism has been replaced and further the breaker is being

replaced by SF6 breaker.

2.3(v) Occurrence at 220kV Barwaha S/s on 11.05.2012


On dt. 11.05.12, at 00:58 hrs., 220 KV “Y” phase L.A. of 220 KV Barwaha – Itarsi feeder

burst at 220 KV S/s Barwaha. There was heavy lightening in the area. This feeder tripped

from both ends. It tripped from Itarsi (remote) end on DPR in Zone I, but at Barwaha end

DPR not operated due to VT fuse failure blocking, therefore, it tripped on back up E/f

protection, it has taken about 426 msec, consequently due to this delay in tripping, other 220

KV feeders on 220 KV bus Barwaha, tripped on DPR Zone II protection from remote ends,

except the 220 KV Barwaha – Handia feeder.

There were no interruption occurred due to this event, 220 KV bus & Transformers were

remain charged due to availability of 220 KV supply from 220 KV S/s Handia. Healthy 220

KV feeders normalized within 30 minutes.

The DPR (Make AREVA, Type 442) of 220 KV Barwaha Itarsi feeder was not operated at

220 KV S/s Barwaha end. It was blocked by VT fuse failure feature due to failure of “Y”

phase PT fuse in C&R panel. On checking the Fuse grip base found defective, which was

then replaced. Since fault duration was about 426 msec, it was close to Zone II operational

time therefore, due to slight delay at 220 KV Handia S/s end, fault disconnected just before

operation of DPR at 220 KV S/s Handia end.

Failed L.A. (20 years old) replaced by new L.A. on 220 KV Barwaha- Itarsi feeder at 220 KV

S/s Barwaha. The 220 KV C&R panels were checked for any discrepancy as observed above.


During these trippings, 05 Generators ( 5 x 50 MW ) tripped at Omkareshwar HPS, and a

generation loss of 125 MWh occurred. However line trippings at Omkareshwar HPS were in

order and other 220 KV feeders at Omkareshwar HPS connected to other 220 KV S/s were

also normal at that time.

Committee discussed the matter and opined that lightening arrestors supposed to divert

the lightening strokes and should not fail due to lightening itself. Also, Leakage current

(LCM) of LAs be monitored. Committee felt that the tripping of Omkareshwar units

were undesirable. MPPGCL may submit detailed report regarding trippings at

Omkareshwar.

This item was again slated for discussion in the next PCM after data from

Omkareshwar is made available.

2.4: System disturbances in MSETCL/MSPGCL system.

2.4(i) Occurrence at 220 kV Kalwa on 12.06.2012 at 17:05 Hrs

MSETCL representative explained the occurrence as below :

On dtd.12.06.12 at 17:06 Hrs at 400KV R.S. Kalwa , 400 KV AREVA make CT of spare single phase unit of BHEL make burst & caught fire. At this instant, the REF protection & instantaneous B/U protection operated & breaker tripped which isolated the CT fault from the system. The failed CT has rising trend of Capacitance & Tan-delta values indicating that CT failed due to insulation failure.

Date of Testing Voltage Capacitance Tan-delta

26/06/2010 10KV 1095pf 0.197%

24/11/2010 10KV 1098.3pf 0.15%

27/11/2011 10KV 1098.0pf 0.976%

01/03/2012 10KV 1099pf 1.13%

07/06/2012 10KV 1093pf 2.051%

This rising trend has developed in new CT which is just five years old & charged in the year 2010 only . The matter was immediately referred to M/s AREVA & representative visited on dtd.20.06.2012 for inspection. The final report is awaited.


The controls cables were found to be damaged of own bay of ICT-1 & spare ICT of BHEL & CGL make. The E/W in between s/s take off gantry & 1st tower of double circuit 220 KV Kalwa- Kharghar & Kalwa- SIEMENS snapped & broken in to pieces. The fumes & flames of busted CT found to be spread over & broken pieces of insulator part of CT hit on ICT tank, 400 KV Bushing etc.

17/05:06:10:543 hrs : ( 1204 msec)

At this instant, it is confirmed that the BB Main II operated. The failed CT was connected to Main-II Bus resulting in to tripping of all the feeder/equipments connected to the bus along with Bus coupler.

The 400KV feeders tripped at remote end also on DT received signal. The indication appeared on ABB, RADSS BB is Y, B, & U (trip). This confirms that the BB did not operate for CT failure. However, it subsequently operated due to fumes & flames spread over on the adjacent/nearby Y & B ph of 3 x 167 MVA ICT – I which were connected to Main Bus II.

17/05:06:11:395 hrs : (2056 msec)

During the above occurrence, the E/W from S/S take off gantry to 1st tower of double Circuit line 220KV Kalwa – Siemens & Kalwa – Kharghar also break down from tower end. This has caused the 3 ph – G fault initially on 220KV Kalwa – Siemens line which is cleared instantly by the distance protection at both ends in Zone – 1.

17/ 05:06:12:675 hrs : (3336 msec)

The above failure of E/W have also caused the transient fault on B ph of 220KV Kalwa –Kharghar line due to swinging whereby the line tripped at Kalwa end & reclosed successfully , However Kharghar end tripped in Zone 2.

During above occurrence, Kalwa – Mulund & Kalwa – Trombay and 220kV Interconnector found to be tripped at Kalwa end only on operation of BB trip relay ABB make (RXMVB2: Speed Relay, ABB Make).

It is also noted that the above trip relay (ABB , RXMVB 2) is found to be operated on < 50 % of rated DC voltage being fast acting devices. Therefore, it may be operating due to DC voltage spike.

To understand the phenomenon, the Additional Aux. relays are incorporated in the BB Tripping of 220KV Kalwa & Trombay and 220kV Interconnector (Drawing Enclosed).

The window and relay indication are as below: 200 MVA SPARE ICT 400/220 kV breaker tripped ( 400KV side )WI: Diff Trip; Breaker D.C fail; buchholz alarm; Fault: 400kv CT of this spare ICT 200 MVA Brust.


RI: 86REF E/F Relay – 1Element 67 IN Directional E/F 1 Element (INST) 86A 5 Element SLD showing the occurrence details and bus bar trip relay circuitry is enclosed at

Annexure-2.4(i).

MSETCL representative further informed that torret CTs are not used for REF

protection of the ICT and the line CTs are wired for REF protection of the ICT.

Committee observed that the tripping of ICT due to failure of line CT is in order, since

the core towards the ICT side might have initially developed the fault and BB side core

might have been wired up for REF protection. The REF protection sensed the fault

correctly and tripped the ICT on REF. It was also observed that simultaneously the BB

protection should have operated since the same CT was wired in the BB protection.

However the BB protection might not have sensed the fault initially as the BB

protection might have been wired up through the CT core towards BB and the failure

of the CT core towards the ICT developed the fault initially and this was the out of zone

fault for BB protection and before the CT blasted completely the fault was isolated by

tripping the ICT. The spread over of fumes & flames of the busted CT caused

carbonization of the adjacent/nearby Y & B ph of 3 x 167 MVA ICT – I which were

connected to Main Bus II thereby creating a bus fault. This time the BB protection

sensed the fault correctly and isolated the fault. The tripping of the 220kV lines due to

breaking of E/W and creating Ph-G faults was in order. The operation of 220kV BB

protection was undesirable due to spurious DC voltage. The performance of the

modified BB tripping scheme should be closely monitored, since an additional relay in

the scheme would introduce additional delay and additional circuitry in the BB

protection scheme. The matter may be referred to ABB.

2.4(ii) Occurrence at 220 KV S/S Khaparkheda on date 19.03.2012


On 19.03.12 at 20:43 hrs Bus bar protection operated due to the initiation of arc across the

R, Y & B Poles (i.e. between blades & jaws) of the 29C Isolator of GT4 bay and is attributed

to the imperfect closing of the 29C Isolator.


Details of trippings at Khaparkheda S No

Name of feeder / equipment

Window Indications

Relay Indications (RYB nomenclature)

1. Busbar protection for 220 KV Transfer bus (i.e. Auxiliary bus) operated and tripped the TBC breaker through its 96 busbar trip relay:

Busbar Protection Operated

Busbar scheme ABB – RADSS with TR and R, T & U flag indications.

i. 220 KV TBC BB Prot optd 96 relay optd. 2. 220 KV GT4 E/F opt. (at PCR

end); LBB operated WI on

GT4 control panel and RTU

DC SCADA IED at GCR end

O/C-E/F relay; LBB relay (B/U + LBB Alstom- KCEG 142), MTR optd.

3. Consequent to operation of the LBB relay of GT4 all breakers connected to 220 KV Main Bus1 including Bus-coupler at Khaparkheda GCR tripped through respective Busbar trip relay 96 as follows:

--- ---

i. 400 KV Koradi ckt BB Prot optd. 96 relay optd. ii. 220 KV Ambazari ckt1 BB Prot optd. 96 relay optd. iii. 220 KV Kanhan ckt2 BB Prot optd 96 relay optd.iv. 220 KV Kaulewada ckt1 BB Prot optd 96 relay optd.v. 220 KV Kalmeshwar ckt BB Prot optd 96 relay optd.vi. 220 KV Wardha ckt BB Prot optd 96 relay optd.vii. 220 KV GT1 MTR Optd 96 relay optd.viii. 220 KV GT3 MTR Optd 96 relay optd.ix. 220 KV GT4 MTR Optd 96 relay optd.x. 40 MVA Stn T/F1 MTR Optd 96 relay optd.xi. 40 MVA Stn T/F3 MTR Optd 96 relay optd.xii. 40 MVA Stn T/F4 MTR Optd 96 relay optd. xiii. 220 KV Bus Coupler MTR Optd 96 relay optd. There were no trippings at Remote ends. Details : Outage was availed by construction wing on date 19.03.2012 on 220 KV Main bus2

at 220 KV S/S Khaparkheda for connecting the bus2 side jumpers for the proposed

commissioning of two new 220 KV circuits to new Khaparkheda S/S. For availing this

outage all the 9 bays that were connected to 220 KV Bus2 were shifted to 220 KV Bus1

through TBC by the S/S operating staff in the morning session. After completion of the

jumpering work by construction, operation of restoration of normalcy of bays was taken up in

hand by S/S operating staff at 17:56 hrs. Shifting operation for six 220 KV bays (viz:


Ambazari2, Kanhan1, Purti, Kaulewada2, GT2 & Stn T/F2) from Bus1 to Bus2 was

completed by 20:15 hrs.

Shifting operation for 7th bay (i.e. GT4 bay) were underway; at the juncture of tripping of

main breaker of GT4 heavy sparking across all the six R, Y & B pole contacts of 29C double

break isolator of GT4 bay (at 20:43 hrs) was observed by the switchyard operating staff.

Subsequently all the breakers connected to 220 KV Main Bus1 at Khaparkheda S/S tripped.

Analysis of Occurrence :

• MSETCL have intimated that they have analysed the occurrence and main cause of

occurrence is the heavy arcing that took place across all the R, Y & B pole contacts

(i.e. jaw & blade) of the double break isolator 29C (i.e. TBC side isolator) in GT4 bay

during shifting operations. Though after post occurrence, the correct closing and

opening operations of 29C isolator of GT-4 bay were confirmed in presence of the

CE, EHV CC O & M Zone, Nagpur, SE, EHV O & M Circle, Nagpur, EE,EHV O &

M Division, Nagpur and SE(TCC) Nagpur, it was felt that there must have been some

gap left between jaw and blade of 29C isolator during pre-occurrence shifting

operation. This might not have been noticed during night hours. At this instance GT4

was running at @183 MW of power. Thus the current of @500A was initially broken

across the imperfectly closed poles of the isolator which initiated arcing. The length

of arc and the magnitude of flashover current gradually increased and subsequently

attained a fault value. The estimated fault current is @10KA.

• This heavy arcing fault was in-zone fault for TBC bus (i.e. Auxiliary bus) and thus

selective operation of Busbar protection (ABB-RADSS) for transfer bus and

subsequent tripping of TBC breaker is IN ORDER.

• The occurrence took place at the very instance of hand-tripping of main breaker of

GT4 during shifting operation. Hence the GT4 remained connected to Main Bus1 (i.e.

29A isolator was in closed position) also the ‘NIT’ switch remained in ‘INTER’

position.

• While other sources connected to the bus-I fed the fault through the TBC, The GT4

directly fed the fault with its own fault contribution (estimated fault contribution by

GT4 @1KA). This caused Earth Fault relay of GT4 to operate at PCR end and issued

the trip command to TBC & Main breaker. However the fault current did not seize as

the Generating Unit-4 was directly feeding the fault. Hence, subsequently its LBB


protection operated and tripped all the breakers connected to Bus1. Hence the

operation of E/F & LBB protection of GT4 and consequent tripping of all breakers

connected to 220 KV Main Bus1 at Khaparkheda is IN ORDER.

• The sequence of operations for shifting of the GT4 bay was later verified and found

OK.

SE(Protection), WRPC enquired whether transfer bus is used for switching of feeders from

one bus to another. Members from Generating company viz. NTPC, CGPL, State Genco’s of

other States etc. informed that switching is done directly through isolators and transfer bus is

not used for switching over from one bus to other bus. This procedure of transferring element

from one Bus to other also takes far lesser time. Transfer bus is used only during when there

is problem with own breaker or own isolator or own CT.

Committee recommended that MSETCL may follow the same procedure that is being

followed by other generators/TRANSCOs. The operation of LBB and BB protection of

220kV transfer bus was in order, since the transfer bus isolator was not closed properly

during transfer of GT4 from Main bus 1 to Main bus 2. However the above occurrence

would have been avoided if the above procedure for transfer of element from one bus to

another bus was adopted.

2.4(iii) Occurrence at 400 KV S/S Khaparkheda on date 05.04.2012


At 400 kV Khaparkheda s/s at 12:41 on 5.04.2012 all breakers connected to 400 KV Bus1

(one and a half bus arrangement) tripped at 400 KV GCR Khaparkheda through respective

Busbar trip relay 96 on operation of LBB protection (50Z1) (Areva Micom make P123 type)

of GTR bay installed in MAHAGENCO GCR, for Bus-I.

Details of trippings at Khaparkheda S No


Window / SCADA

Indications


1 LBB relay of GTR bay operated at Mahagenco’s PCR end and tripped following breakers connected to 400 KV Bus1 through respective BB trip relay 96 as under:

---- LBB relay 50Z1 (Areva Micom P123) operated at PCR with trip LED indication. Fault data (Record 25): Ia = 0; Ib=1.25A; Ic=0; Faulted Phase: None; Tme: 12:41:25:22; Dt 05.04.12


i. 400 KV GTR 96 relay optd 96 relay (GTR was OFF) Time: 12:41:44:174 hrs)

ii. 3X167 MVA 400/220 KV ICT1

96 relay optd 96 relay (Time: 12:41:44:174 hrs)

iii 3X167 MVA 400/220 KV ICT2

96 relay optd 96 relay (Time: 12:41:44:174 hrs)

iv 400 KV Stn 5A 96 relay optd 96 relay (Time: 12:41:44:174 hrs) v 400 KV Stn 5B 96 relay optd 96 relay (Time: 12:41:44:174 hrs)

There were no trippings at Remote ends. MSETCL representative stated that on enquiry with MAHAGENCO it was intimated that

GTR was already OFF. The pre-synchronisation trials of the GTR bay were in progress and

the relay operated at the instance of switching OFF / ON the auxiliary DC to the Control &

Relay panel. This trial was a part of the routine test. However at the instance of switching of

auxiliary supply, the ‘any trip’ pulse from MTR (Master Trip Relay) was active to the LBB

relay as the MTR was not resetted.

The numerical busbar scheme Sifang CSC 150 is provided at 400 KV Khaparkheda GCR.

The in-built LBB function of this relay is used for LBB protection for all the bays except

GTR. As the control of GTR bay is with Mahagenco, the LBB relay for this bay is also under

the purview of Mahagenco and the LBB command for GTR is externally connected to the trip

bus of busbar scheme. The matter of undesired operation of the LBB relay has been taken up

with MAHAGENCO and with M/S Areva.

As one and a half breaker bus arrangement is provided at GCR, the breakers connected to

Bus-1 & Bus-2 are clearly identified; hence isolator interlock is not provided for

identification of breaker. In the present scheme the LBB command of GTR is therefore

directly connected to the trip bus without such interlock.

The matter for review of the protection scheme for introduction of Breaker or Isolator

interlock is also taken up with M/S Easun Reyrolle Ltd.

The tripping of breakers connected 400 KV Bus-1 consequent to operation of LBB did not

cause any interruption of supply, since there is a one and a half breaker bus arrangement. The

GTR was already OFF and other bays were being fed through respective Tie breaker / Main

breaker.


Committee opined that this is human error and this occurrence could have been

avoided if proper procedure would have been followed. Also, MSPGCL were

instructed to provide necessary interlock in the scheme at Khaparkheda Generating

station. After providing the interlock the compliance report stating details of the same

may be forwarded to WRPC.

2.4(iv) Occurrence at 220 KV S/S Warora on date 13.05.2012


On date 13.05.2012 at 08:58 hrs 220 kV Bus bar Protection (REB 500 ABB Make) of 220

KV WPCL bus operated and tripped following breakers through respective B/B trip relay

96 including bus sectionalizer breaker

Sr No


Window Indications


a 220 KV WPCL Ckt-1 nil 96 BB trip relay b 220 KV WPCL Ckt-2 nil 96 BB trip relay

Trippings at Remote ends :

S No

Name of S/S Name of the feeder

Window Indications Relay Indications

1 220 KV GCR Chandrapur

220 KV Warora Distance protection trip

Dist Zone-2, R-Y-N, XTF=40.6 KM, 86

2 220 KV Wani 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,86

3 220 KV Wardha 220 KV Warora Distance protection optd.

Dist Zone-2, R-Y-N, XTF=73 KM,86

4 220KV Hinganghat 220 KV Warora Distance protection optd.

Dist Zone-2 R-Y,XTF=48.76 KM,86

Details of occurrence : On date 13.05.2012 at 08:58 hrs, bursting sound was heard from the switch yard of 220 KV

S/S Warora, followed by total a. c. failure at this S/S. On Yard inspection ‘R’ ph CT (Make:

SCT Gaziabad, Sr. no.: 2009/1766, Mfg year: 2009) of 220 KV WPCL Bus-sectionalizer

found to have burst. The failure caused damage to R-ph pole of Siemens make bus-

sectionalizer breaker and R-ph insulator of incoming side and outgoing side isolators and

carbonisation of adjoining Y-ph CT. 220 KV Bus bar Protection scheme (ABB - REB 500)

provided for 220 KV WPCL bus operated alongwith the newly commissioned 220 KV Bus

bar Protection scheme (Make: NR-RCS 915 ) provided on 220 KV old Warora bus which


was kept on alarm mode.

Analysis of occurrence :

• The work of extension of existing 220 KV bus in the extended section of

switchyard, providing of bus-section breaker and allied work of providing

switchgear, protection and SCADA etc was carried out by M/S WPCL on turnkey

basis. On date 13.05.2012, at 08:58 Hrs the R-ph CT of 220 KV Bus-sectionalizer

burst which created bus fault in WPCL bus and consequently 220 KV Bus bar

Protection (ABB-REB 500) of 220 KV WPCL bus operated and tripped 220 KV

WPCL Ckt-I & II breakers through respective B/B trip relay 96 including Bus-

sectionalizer breaker at Warora end is in order.

• Remote end indication at Chandrapur, Wani, Wardha, Hinganghat indicate the

involvement of R & Y phases in the fault, indicating that the smoke of the burst R-

ph CT must have created a bus fault w. r. to Y phases. This fault was being fed

from existing 220 KV Warora bus. The Newly commissioned numerical 220 KV

Bus bar protection scheme (RCS 915 Make-NR) provided for 220 KV old Warora

bus operated but since the same was kept on alarm mode so as to confirm its

stability on through fault, no tripping at local end at Warora S/S occurred. Thus

220 KV bus fault on 220 KV old Warora bus caused all the sources to trip at their

respective end on distance zone-2 (R & Y phases). Tripping of all sources at

remote end caused total a.c. failure at 220 KV S/S Warora.

• The occurrence caused loss of generation @436 MW of M/S WPCL. Also the load

of Warora Railway TSS of @ 2 MW and local load of @ 43 MW was affected.

The load of @ 385 MW of Hinganghat, Wardha, GCR Chandrapur and Wani

feeders was thrown off to other lines in the grid. The 220 KV grid however

remained stable.

• The newly commissioned 220 KV Bus bar protection scheme (RCS 915 Make-NR)

which was kept on alarm mode to confirm its stability on through fault is now kept

on trip mode.

Committee observed that the tripping of lines from remote ends in zone 2 were in order

since the BB protection scheme was kept under observation(in Alarm mode).

2.4(v) Occurrence at 220 KV S/S Butibori on date 19.06.2012


MSETCL have informed that at 03:50 hrs on 19.06.2012 at Butibori S/S all breakers

connected to 220 KV Main Bus-1 including Bus-coupler tripped through respective 96 BB

tripped.

Details of trippings at Butibori: S No

Name of the feeder / equipment

Window Indications Relay Indications

1 LBB Protection of 220 KV Indorama feeder operated and tripped all breakers connected to 220 KV Bus 1, including Bus-coupler, through respective 96 BB trip relays, as follows:

-

2 220 KV Indorama LBB protection optd 2/50Z, 96 3 220 KV Inox i)Pilot wire prot optd.

ii)Pilot wire defective 96

4 220 KV Buscoupler Nil 96 5 50MVA 220/33 KV T/F-3 Nil 96 6 220 KV Koradi Trip relay optd. 96

There were no trippings at remote end.

Analysis of occurrence : MSETCL have analysed the incidence as below :

1. There was a fault on 11 KV bus at M/S Indorama company emanating from 220 KV

Butibori S/S. For this fault, 11/33 KV Tie 4 & 5 T/F tripped on over-current relay at

consumer end with fault current @ 1.71 KA and 1.63 KA on 33 KV side in about 232

msec.

2. The matter of operation of LBB protection of 220 KV Indorama feeder was

investigated in detail and the problem of contact of trip relay RXMS1 was detected.

It was found that the D.C logic of LBB relay on 220 KV Indorama panel at 220 KV

Butibori S/S was through via bus bar protection trip relay (96) contact which was

found stuck in make condition. The fault current was above the pick up setting of

LBB relay . Current setting of LBB relay is 0.8 A sec(CTR-400/1A) that is 320 A

primary with 200 msec timer setting. As D.C. logic of the LBB relay was already

through and fault current was above pick up setting of LBB relay resulting into

operation of LBB protection of 220 KV Indorama feeder. The problem of contact of


trip relay RXMS1 was later attended and confirmed that the D.C. logic of LBB relay

is not through.

3. It is to note that back up protection of 220 KV Indorama feeder did not operate for the

above fault as the fault current was just above the pick up setting of LBB relay and

Earth fault relay will take time @0.5Sec to operate. The setting of Back up O/C and

E/F relay (Make: EE, Type: CDD) are:

CTR PS TMS O/C R & B 400/1A 100% 0.08 E/F 40% 0.08

4. The total fault current shown at 33 KV level at M/S Indorama end is @3.34KA

(Ref: Annexure:2). For this fault, The fault current shown by 220 KV side relay of

220/33 KV T/F at 220 KV Butibori S/S end is @500 A. From this it appears that

@500 A fault current is fed from 220 KV bus at 220 KV Butibori S/S. For 500 Amp

fault current the time require for E/F relay to operate is calculated as under:

500A/160=3.1 means for 3 times current TOP is 6.302 and TMS setting for E/F is

0.08. Thus time requires to operate E/F relay comes out to be @504 msec.

From this it appears that before operation of E/F relay of T/F, the LBB relay of

Indorama feeder operated with pick up setting of 320 A primary with 200 msec timer

setting.

5. The occurrence caused interruption to EHV consumers M/S Indorama & M/S INOX

(Load 1MW and 2.5 MW respectively) and also local 33 KV load of @ 12 MW

was affected. The load @ 55 MW on 220 KV Koradi feeder was shared by other

feeders and the grid remained stable.

Committee discussed the incidence and opined that the operation of LBB protection of

220 KV Indorama feeder is undesirable and the operation of LBB relay of 220 KV

Indorama feeder was mainly due to contact stuck up (low contact gap) problem of trip

relay RXMS 1 (since RXMS 1 are high speed relay), which made the trip logic of LBB

relay through and the load current was higher than the LBB current setting.

Committee opined that trip through logic of LBB relay should be wired up through

RXMH relay (since these are slow speed relays) instead of RXMS 1 relay for desirable


operation of LBB.

ITEM NO. 3: Other points:

ITEM NO. 3.1: Implementation of SPS for Agra-Gwalior corridor. Member Secretary(I/C), WRPC, intimated that NRLDC vide letter dated 5.8.2012 requested

for discussion and finalization of setting for SPS for tripping of Agra-Gwalior lines or Bina-

Gwalior lines.

Following comments were communicated to NRPC vide letter

No.WRPC/Protection/SPS/2012/1287 Dated 16.08.2012.

1. SPS designed by NR is preemptive action to control overloading of Agra-Gwalior and Bina-

Gwalior corridor between WR and NR and therefore summated values for both the circuits

may be considered for operating load shedding in NR.

2. Proper load shedding in NR only would reduce the flow on above corridor. The effect of

backing down of generation in WR would not be so sensitive to reduce the flow on above

corridor. Therefore, Case-1 and Case-2 actions to be taken by NR constituents are in order.

3. As far as backing down of 500 MW generation in Western Region is concerned, We have

requested WRLDC to carry out sensitivity study to find the effect of backing down/tripping

of various generators on flow on Bina-Gwalior and Agra-Gwalior lines.Therfore

presupposing backingdown of generation at VSTPS or Korba may not be appreciable.

4. In case of angular separation between Gwalior and Agra beyond permissible limit planned

separation between the two grids alongwith load shedding schemes may also be planned/

incorporated.

5. Sufficient time delay and interlocks are required to be provided for backing down/tripping of

generation in WR after ascertaining that sufficient load shedding is carried out in NR and

thereafter according to flow on Agra-Gwalior and Bina-Gwalior lines backing down

quantum can be decided.

6. Appropriate action plan may be devised in case of tripping of both Agra-Gwalior lines

7. Above points alongwith the sensitivity study results submitted by WRLDC would then be

discussed in ensuing Protection sub-Committee of WRPC and thereafter in TCC & WRPC

forum and then the outcome would be submitted to NR.

WRLDC have carried out studies to check the sensitivity of various options as below :

• As per studies, after tripping of Agra-Gwalior lines power flow over other inter-regional


lines between NR-WR and WR-ER would increase. Higher sensitivity has been observed

with reduction of generation at :

i) Korba, Sipat, Vindhyachal STPS to control power flow towards ER

ii) CGPL & SSP to control power flow in Zerda-Bhinmal-Kankroli lines

iii) Satpura TPS to control power flow in Bina-Mehgaon-Gwalior lines

iv) ISP and Satpura TPS to control power flow in Badod-Kota-modak lines

• The SPS shall also take signal from another SPS to be provided at Bina for loss of D/C

lines of Bina-Gwalior

• Inter-tripping scheme at Bina to control ICT loadings

• SPS had been made operational in NR since 18.08.2012 for load shedding of 500 MW in

UP and Rajasthan whenever flow on Gwalior-Agra D/C crosses 500 MW/Ckt or if flow

crosses 750 MW in case of only single ckt. Availability.

The loss of export to NR may result in high voltages at Bina & Gwalior and inter-tripping

shall be provided to trip one ckt of 400 kV Bina-Gwalior D/C (if both ckts are available) or

tripping of one ckt of Satna-Bina. (preferably 765 kV). The voltage grading for tripping of

lines at Bina may be coordinated accordingly so that 400 kV Bina-Bina D/C and 400 kV

Bina-Shujalpur D/C should not trip and positively avoided.

As per studies 500 MW relief from all the stations mentioned above are required.

In this a discussion evolved among members. The gist of discussion is given below.

CE, SLDC, MPPTCL stated that Satpura TPS normally operate on Technical minimum and

therefore Satpura TPS may not be considered for above backing down and instead JP Bina

Power Station may be considered. Further SSP and ISP being a hydro station and the

generation from this station during such occasions may not be always available. Hence

alternate generation backing down may be explored.

He further stated that similar SPS is also required to be designed for Badod-Modak and

Badod-Kota lines or alternatively load in Rajasthan/UP (near Modak & Kota) to the tune of

100 MW should be tripped.

In view of above it was decided that backing down at JP Bina instead of backing down at

Satpura TPS and backing down at CGPL instead of backing down at SPS and ISP may be

included in the scheme for controlling the flow from WR to NR.


Regarding commercial mechanism to compensate for UI payable due to above for the

concerned stations as above, GM, WRLDC intimated that at this stage suspension of UI for

these stations or post-facto revision of schedules (schedules as per actual) may be done by

them as done in case of transmission constraints. Detailed commercial mechanism would be

formulated by WRLDC and then it may be discussed in ensuing Commercial Committee.

Committee in-principle agreed with the above arrangement. Details would be prepared

by WRLDC and put up for approval in the next WRPC meeting. NRPC would be

intimated of having identified units for 500 MW backing down required for proposed SPS

scheme.

ITEM NO. 3.2: Repeatation of PLCC frequency for various 400 kV lines under WRSS-

II & Mundra UMP scheme

SE(Protection), WRPC stated that ACE(Transmission), GETCO during 114th PC meeting

intimated that PLCC frequencies already in use on 400 kV at GETCO s/s are repeatedly used

by PGCIL for 400 kV D/c Ranchodpura(Vadavi)-Limbdi(Chorania), 400 kV D/c

Ranchodpura-Zerda(Kansari), 400 kV Ranchodpura-Bachau and 400 kVLimbdi(chorania)-

Mundra commissioned under WRSS-II and Mundra UMPP scheme without any concurrence

fromGETCO. He further intimated that as per technical report, CE1, IEC 663:1980 clause

No. 4.1.2.C, “The same frequency maybe used for two different PLCC stubs working on

lines forming common system if two are separated by at least two line sections with

intermediate sub stations.”

PGCIL has used frequencies already used in service for GETCO without any concurrences

from GETCO for other stations and warned that the practice of utilizing repeated frequencies

for PLCC may cause mal operation of system further causing instability in the grid. He

further intimated that 8 KHz band is used for every link.

PGCIL/WRLDC representative during 114th meeting of Protection Committee intimated that

PGCIL might have used repeated frequencies due to non-availability of the bandwidth. He

further intimated that elsewhere 4 KHz band is used safely in the system and the problem of

non-availability of bandwidth can be resolved if 4 KHz band is used in GETCO. However,

he would confirm the same after consultation with WR-II. PGCIL/WRLDC were requested

to followup the matte with WRTS-II, PGCIL.


ACE(TR), GETCO vide letter No. CE(Tr)/SE/Telecom/PLCC/39/1012 dated 23.07.2012

addressed to PGCIL, WR-II (have intimated that despite several reminders to PGCIL

regarding repeated use of PLCC frequencies for 400 kV transmission lines under WRSS-II &

Mundra UMPP scheme, matter have not been responded/solved by PGCIL.

PGCIL, WR-II representative intimated that they have referred the matter to their

Corporate office and necessary action is being taken. SE(Protection), WRPC requested

PGCIL and GETCO to sort out the matter bilaterally for which both PGCIL and

GETCO agreed.

ITEM NO. 3.3: Review of low frequency and high frequency trip setting for generating stations in WR.

SE(Protection), WRPC stated that during recent grid disturbance in NR/ER/NER on

31.07.2012, WR grid was isolated from rest of NEW grid and WR frequency almost touched

51.5 Hz. Following units reported to have tripped in WR during isolation of WR from

NR/ER :

Station/ Unit Date/Time Reason MW Adani, Mundra-7 31.07/13:01 SPS operation 660 EPGL-2 31.07/13:02 Feed water pump tripped 600 KLTPS-2 31.07/13:02 Geenrator protection operated 70 DSPM -1 31.07/12:57 UAT HT side overcurrent relay 250 DSPM -2 31.07/12:57 Over frequency relay operated 250 Sipat STPS 31.07/13:01 Over frequency relay operated 500

Member Secretary (I/C), WRPC stated that from above it is clear that most of the units have

tripped on protection irrelevant with the above occurrence and trippings were undesirable,

however it has given relief as required at that time. It is necessary that particular relief is

received through designed tripping of units as per setting. Also, the generator trip

settings/timings required to be staggered to avoid simultaneous/excessive tripping of all

generators at given station/control area/State. In such an event total station may face

blackout and may result into low frequency in the grid in the event of tripping more than

required generation.

Committee reviewed the trip settings of various units and recommended that

generation of around 1500 MW is required to be tripped/backed down during high

frequency operation of the system at specific generating stations so as to avoid


transmission congestions and over voltage problems. Committee further felt that

generator over frequency trip are not meant for tripping the units as a system special

protection scheme and the over frequency trip settings suggested by the OEM of the

generators be retained. WRLDC was requested to study and identify the generating

units which are required to be tripped at system frequency above 51.5Hz. as a design

feature notwithstanding trip setting adopted by other units in grid.

ITEM NO. 3.4: Protection Auditing by CPRI

Member Secretary (I/C), WRPC stated that during the meeting held at CEA on recent grid

disturbance in NR, importance of protection auditing was discussed. All the members are

familiar with protection of power system but new to auditing of the same. In order to address

the system security concerns protection audit of substations is essential and actively being

pursued in India. The aim of the audit is to review the protection philosophy, relay

coordination and protection settings, healthiness of DC system, healthiness of

communication link with respect to protection system, healthiness of Time synchronization

of generating Units, healthiness of disturbance recorders and event loggers, protection testing

procedures and protection system technology.

Accordingly, Shri Shivkumar Aradhya, CPRI, Bengaluru made a detailed presentation on the

ins and outs of protection auditing, wherein he covered aspect like scope of audit, stages of

audit, methodology adopted for audit, facilities available at CPRI, and case studies of DTL.

The full presentation is available on WRPC website.

Member Secretary, WRPC enquired CPRI whether any license has been granted to

CPRI or CPRI is certified as statutory body for protection audit. In reply, CPRI stated

that presently there is no license or certificate granted to CPRI and CPRI is carrying

out audit of protection system of State and other utilities as per requests received from

them. Also MS enquired whether only stand alone audit is possible or whole scheme

such as bus-bar or differential scheme can be audited. CPRI representative stated that

online scheme can not be audited however instrument transformer accuracy and setting

of relays individually could be audited. The presentation has been uploaded on WRPC

site.

ITEM NO. 4: Any other issues.


entered NR. Further prior to closing the AC Bypass, NTPC-Vindhyachal

was running normally with WR system. It is unfortunate that some problem

of NR system bypass got ‘extended into’ Vindhyachal and tripped the units.

3) As such Committee recommended that Vindhyachal units tripped under

grid disturbance and appropriate commercial issues may be taken up in the

CCM forum of WRPC.

4.2 CGPL Synchronization issue.

CGPL representative intimated that on 30.07.2012 at around 06:15hrs, CGPL Mundra was

isolated from the grid and survived with house load. The loading of the generators which was

around 700MW dropped to @124MW after isolation. At around 06:19hrs unit-2 tripped on

reverse power and Unit-1 continued on house load generating about 62MW. 400 kV CGPL-

Mundra line was in service. While closing 400kV Bhacchau-Ranchodpura ckt 2 at

Ranchodpura S/S by GETCO there was a large synchronizing current of the order of 26 kA

on all three phases and the unit at CGPL Mundra tripped. There were damages to the unit and

the original manufacturer has to be called and it took around a month to bring back the unit.

He apprehended that the synchronization of 400 kV Bachau-Ranchodpure ckt 2 was

performed without using the check synchronization facility and this was due to improper

synchronization.

GETCO representative intimated that synchronizing facility is available at 400kV

Ranchodpura. Further GETCO was instructed by WRLDC to close the above line. However

it was not told to them that CGPL was on islanded mode / house load.

GM, WRLDC stated that this was the problem of communication, as CGPL intimated that

their units were islanded on house load, which was not understood by operators at at

WRLDC. He opined that CGPL could have intimated that their units were islanded from the

grid. To this CGPL pointed out that they have no way of knowing whether they are islanded

or not from the grid.

Committee discussed the occurrence and observed the following:

1) The large currents in all the three phases resulted due to improper

synchronization. It is well known that when two systems are synchronized with

large phase difference, it results in a fault like situation on all the phases, which


entered NR. Further prior to closing the AC Bypass, NTPC-Vindhyachal

was running normally with WR system. It is unfortunate that some problem

of NR system bypass got ‘extended into’ Vindhyachal and tripped the units.

3) As such Committee recommended that Vindhyachal units tripped under

grid disturbance and appropriate commercial issues may be taken up in the

CCM forum of WRPC.

4.2 CGPL Synchronization issue.

CGPL representative intimated that on 30.07.2012 at around 06:15hrs, CGPL Mundra was

isolated from the grid and survived with house load. The loading of the generators which was

around 700MW dropped to @124MW after isolation. At around 06:19hrs unit-2 tripped on

reverse power and Unit-1 continued on house load generating about 62MW. 400 kV CGPL-

Mundra line was in service. While closing 400kV Bhacchau-Ranchodpura ckt 2 at

Ranchodpura S/S by GETCO there was a large synchronizing current of the order of 26 kA

on all three phases and the unit at CGPL Mundra tripped. There were damages to the unit and

the original manufacturer has to be called and it took around a month to bring back the unit.

He apprehended that the synchronization of 400 kV Bachau-Ranchodpure ckt 2 was

performed without using the check synchronization facility and this was due to improper

synchronization.

GETCO representative intimated that synchronizing facility is available at 400kV

Ranchodpura. Further GETCO was instructed by WRLDC to close the above line. However

it was not told to them that CGPL was on islanded mode / house load.

GM, WRLDC stated that this was the problem of communication, as CGPL intimated that

their units were islanded on house load, which was not understood by operators at at

WRLDC. He opined that CGPL could have intimated that their units were islanded from the

grid. To this CGPL pointed out that they have no way of knowing whether they are islanded

or not from the grid.

Committee discussed the occurrence and observed the following:

1) The large currents in all the three phases resulted due to improper

synchronization. It is well known that when two systems are synchronized with

large phase difference, it results in a fault like situation on all the phases, which


happened in this case.

2) Prior to synchronization, the communication gaps indicates that operator at

GETCO was not aware that by closing a 400 kV Ranchodpura-Bachau line, they

were attempting to synchronize an islanded system with the rest of the grid. If

GETCO had been instructed by WRLDC that by closing the above line, two

islanded systems are being synchronized, permissible limits of synchronization

could have been made stringent ( as done for generator synchronization) and

suitably taken care of, so that the synchronization is smooth. This would have

avoided the damage to the machine at CGPL.

3) Committee recommended that in future, WRLDC, before giving codes, should

be fully aware of the situation and also make aware any intervening or

coordinating agency about the situation, particularly for lines connecting to or

near generating stations.

4) Committee recommended that flow of information and communication from

WRLDC to SLDC / intervening agency should be clear and explicit.

ITEM NO. 5: Date and Venue of the next meeting.

The next protection Committee meeting will be held during the month of December -12. The

date and venue will be intimated separately.

ANNEXURE-I

1 Shri S.A.Patel Ex. Engineer (Testing)

2 Shri. P S Kulkarni Superintending Engineer, Nagpur3 Shri. Ajit Pachori Executive Engineer, Mumbai

4 Shri S G Kelkar ED (O), Mumbai5 Shri Shinde Chief Engineer , SLDC, Kalwa6 Shri Shashank Jewalikar Superintending Engineer (T &C), Auragabad.7 Shri A M Kondawar Superintending Engineer (TCC), Nagpur8 Shri Vasant Pandey EE, SLDC, Kalwa9 Shri B L Pasarate SE(TCC), Vashi

10 Shri P M Deshpande EE(Testing), Yavatmal11 Shri P S sale SE(TCC), Karad12 Shri P R Deore CE(Trans.), Pune13 Shri R S Parulkar EE(T&T), Chandrapur

14 Shri Bende P R Chief Engineer, SLDC, Jabalpur

15 Shri R S Shrivastava Superintending Engineer, 400kV S/S, Bhopal16 Shri Sunil Yadav Superintending Engineer(T&C) , Indore.

17 Shri Prakash C. Soni Superintending Engineer (Engg.), MPPGCL,Jabalpur

18 Shri M Z Rehman Superintending Engineer (T&C), Bhilai

19 Shri S K Mehta Superintending Engineer(O&M), Raipur20 Shri P Kolay Superintending Engineer(Opn.), Korba west

21 Shri Ruchir Oza SO/E , TAPS-3&4, Tarapur 22 Shri Ashwin Yadav SO/E , TAPS-3&4, Tarapur 23 Shri V M Daptardar SME(E), TAPS 1&2 , Tarapur

LIST OF PARTICIPANTS

115th Protection Committee Meeting held on 6th & 7th September 2012 at Pune(Mah.).

GETCO (Gujarat Energy Transmission Corporation Limited)

MAHAGENCO (Maharashtra State Power Generation Company Limited)

MSETCL (Maharashtra State Electricity Transmission Company Limited)

MPPTCL (Madhya Pradesh Power Transmission Corporation Limited)

MPPGCL (Madhya Pradesh State Power Generation Co. Ltd.)

CSPTCL (Chattisgarh State Power Transmission Co. Ltd.)

CSPGCL (Chattisgarh State Power Generation Co. Ltd.)

NPCIL (Nuclear Power Corporation of India Limited)

24 Shri Jitendra Tewari AGM (EMD-I/c) Vindhyachal STPS25 Shri R K Aash AGM(Elect.), NTPC, Kawas.26 Shri Prasun Chakraborty AGM(EMD-I), NTPC, Sipat.27 Shri D Roychowdhary AGM WR-II, Raipur28 Shri Oswald Menezes DGM(OS)., NTPC,WR-I,Mumbai

29 Shri Kundan Rathod Sr. Manager( E M), RGPPL.

30 Shri M A K P Singh Member (Power), NCA31 Shri Rajesh Sharma Assist. Director, NCA

32 Shri Ravi A. Wadyalkar Manager , WRTS-I, Nagpur33 Shri Brahananda Doppani Manager (O&M), WRTS-II, Vadodara.

34 Shri Murlikrishnan Asst. Gen. Manager35 Shri A Uppal Chief Manager36 Shri Girish Jawale Manager, Mumbai

37 Shri K N Athavale GM(Electrical)

38 Shri Uday Trivedi Manager, Ahmedabad.

39 Shri Pravin Chitral Assistant Gen. Manager (O&M), Ahmedabad.40 Shri Milind Modi Manager (Trans.), Ahmedabad.

41 Shri M. R. Waigankar Sr. Manager (T&P), R-Infra, Mumbai

42 Shri S. Aradhya Addl. Director

43 Shri P Pentayya GM, POSOCO, Mumbai44 Shri V A Murty DGM, POSOCO, Mumbai45 Smt. Pushpa Seshadri Chief Manager (OS), POSOCO,Mumbai

46 Shri S D Taksande Member Secretary I/C47 Shri Satyanarayan S. Superintending Engineer (O&S)48 Shri M M Dhakate Superintending Engineer (P)49 Shri P D Lone Executive Engineer (Comml)

NTPC Ltd.

RGPPL,Ratnagiri

NARMADA CONTROL AUTHORITY

PGCIL (Power Grid Corporation of India Limited)

TPC (Tata Power Company)

Coastal Gujrat Power Ltd.,Mundra

Adani Power Ltd, Ahmedabad

Torrent Power Ahmedabad

REL (Reliance Infra Ltd.)

CPRI , Bangalore

POSOCO WRLDC (Western Regional Load Dispatch Centre)

WRPC (Western Regional Power Committee)

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