Meeting of Protection Coordination Sub-Committee (PCSC

Minutes of the 54

th Meeting of PCSC held on 26

th May, 2016 Page 1

SOUTHERN REGIONAL POWER COMMITTEE BENGALURU

Minutes of the 54th Meeting of Protection Coordination Sub-Committee

(PCSC – 54) of SRPC held on 26th May, 2016

1. Introduction

The 54th meeting of Protection Coordination Sub-Committee (PCSC-54) was held on 26th May, 2016 in the Conference Hall of Southern Regional Power Committee (SRPC), Bangalore. The list of participants is enclosed at Annexure-I.

Sh. S.R. Bhat, Member Secretary (MS), SRPC welcomed Members and Participants to the meeting and briefed them on the following:

Informed members that a special meeting was held on 19.05.2016 to deliberate on the pending issues in respect of NPCIL/ BHAVINI. In the meeting concrete assurances were obtained from NPCIL/ BHAVINI on a host of issues like planned outages of NPCIL Units, Reactors’ installation at KGS, KKNPP, enabling of A/R feature on evacuation lines of NPCIL/ BHAVINI, Tap-changing & MVAR-Interchange at KGS and KKNPP, pending SCADA Inputs from NPCIL/ BHAVINI, compliance of PSAG-14 recommendations, etc, and hoped that NPCIL/ BHAVINI would initiate steps to meet the agreed timelines.

Apprised members that Protection Audit Review of Stations (15 in number) under Task-2 by the Consultant was under progress. Audit of 13 Stations had already been completed. The remaining two Stations, viz., 400/220 kV Raichur TPS (8-10 June, 2016) and 220 kV Nagjheri HPS (14-16 July, 2016) would also be audited shortly. He requested Constituents’ active cooperation in completing Task-2 activities to the satisfaction of all parties involved.

Briefed members that the data required for the review of Islanding Schemes of the Southern Region had been furnished by the concerned Constituents (TSTRANSCO, TANTRANSCO & KSEB), and the details of the Islanding Schemes along with study results would be shortly furnished for implementation by the concerned Constituents.

Wished Shri P. Raghuram, Executive Director, SRLDC on his getting superannuation by May, 2016, and placed on record the invaluable contribution made by him to various SRPC forums in general and PCSC forum in particular. Describing his towering personality, MS, SRPC stated his absence would be a colossal loss not only to his parent organization, but to power sector as well. So thorough was his command over the subject that he had been able to take firm stance and get his way through on many a complex issue, and was the guiding/ central force behind the disciplined operation of SR-grid as it was today. Then MS, SRPC requested ED, SRLDC to say a few words on the gracious but painful occasion for the benefit of SR-Constituents.

ED, SRLDC stated that when he started his career as PLCC Engineer with NTPC, he, being an E.C.E. graduate, knew nothing about protection. However, when later asked to look after protection related works, he started focussing on the fundamentals, and with the help/ guidance of his seniors, he was able to learn them quite effectively, and apply in practical situations. In this regard, he placed on record the guidance he received from Mr. Babu, Div.

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th Meeting of PCSC held on 26

th May, 2016 Page 2

Engineer, APTRANSCO and Mr. Venkateshwarulu, Div. Engineer, APTRANSCO in mastering protection concepts and disturbance analysis. He stated that when PGCIL took over RLDC, SR-grid was rather undeveloped, and there used to be frequent black-outs in the region. However, with the concerted efforts of all SR-Constituents, the situation improved significantly so much so that there was not even a single black-out in the region in the past 10 years. In this regard, the introduction of Special Protection Schemes as a defence mechanism was specially mentioned. The success of Talcher – Kolar SPS, the first of its kind, led other players in the Indian power sector to emulate & reap the benefits of properly designed SPS’s. ED, SRLDC stated that he had been attending PCSC meetings since 1994, and was witness to the marked difference in the way the things are analyzed in terms of thoroughness and quality, and wished to follow them even after retirement. He expressed his gratefulness to PCSC forum for giving him an opportunity to develop himself, and wished good luck to all. On this, PGCIL (SR-II) representative stated that Raghuram Sir would be remembered for the camaraderie he enjoyed with all including the junior staff posted in sites, and for the down-to-earth approach he adopted in resolving various issues. He was so systematic & meticulous in analyzing the things, esp. tripping events, that root-cause analysis often turned out to be a plaything for him, and he learnt a lot from him in this regard. Describing Raghuram Sir, KPTCL representative mentioned that the relation he shared with him was one that existed between a Principal and a Student, and every rendezvous with him was more than just a learning experience for him. With his pragmatic approach, he was able to enforce the much needed discipline in the operation of SR-grid, and rein in the unwarranted trippings that used to fester SR-grid in the past. Requesting for his continued guidance in future, he wished him a happy retired life. KSEB representative recounted that Raghuram Sir would be remembered not just for the knowledge he commanded or for the contribution he made to SR-grid, but also for the philosopher-guide role he played with his subordinates. With regard to any issue, he always asked only the relevant questions, and once he got right answers, he was also quick to appreciate others - a rare/ quintessential quality needed to motivate subordinates. In this regard, he briefly shared his own experience as to how he got encouragement from him when a black-out of Kozhikode took place in the past. MS, SRPC thanked all Constituents & Members for all the nice words, and stated that the admiration all Constituents had for ED, SRLDC shows how popular & committed he was, and it would be really painful to miss him in future meetings. On behalf of all PCSC members, he wished him success in all future endeavours.

22. Confirmation of the Minutes of the 53rd PCSC meeting held on 28th April, 2016

SE (Protection), SRPC stated that the Minutes of the 53rd meeting of the PCSC had been circulated vide SRPC letter No. SRPC/SE-III/ PCSC-53/ 2016/ 3031 – 64 dated 16.05.2016.

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th Meeting of PCSC held on 26

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Subsequently, KSEB vide their e-mail dated 25.05.2016 informed that KSEB remarks under III.2 and III.3 tripping events included in Annexure-II of the minutes should be modified as follows:

“KSEB:

Prior to the tripping event, single-phase auto-reclose feature in Main-II relay (CG make ZLV type) was in enabled condition. This feature requires breaker open status of each pole for successful reclosing operation. This had not been wired. Therefore, for each single-phase tripping in Zone-1, in the absence of breaker open status of that particular pole, the relay would initiate three-phase lock-out tripping.

Remedial action:

Now as a remedial measure, they had disabled A/R feature of this relay, and provided it through a separate external A/R relay (EE make, VARM type), and is working in good condition”.

With above modification, the Minutes of the 53rd Meeting of PCSC were confirmed.

3. Details of Grid Disturbances (GD’s), Grid Incidents (GI’s), Line Trippings due to Auto-Reclose

non-operation and PLCC mal- operation. The trippings due to GD’s, GI’s, Auto-Reclosure failure/ non-operation, and PLCC mal-operation

that had occurred during the period April - May, 2016 were discussed in the Meeting. The details of the tripping events including relevant PMU plots presented by SRLDC in the meeting are given at Annexure–II for kind reference. The deliberations and recommendations of the PCSC-forum are given at Annexure–III for further needful action.

4. Status of pending PCSC recommendations The status of implementation of pending PCSC recommendations was discussed in the meeting.

The Constituents had been requested to kindly submit the status of their compliance latest by 24.06.2016. The updated status of the same as on 10.06.2016 is enclosed at Annexure–IV.

5. Remedial measures/ Action taken for the tripping incidents of the transmission elements

under forced outage The tripping incidents of the transmission elements under forced outage for which the remedial

measures/ actions taken still awaited were discussed in the meeting. The Constituents had been requested to kindly furnish the remedial measures/ action taken in time so as to forward the same to Central Electricity Authority. The updated list of the same as on 10.06.2016 is enclosed at Annexure-V.

6. Certificate for Healthiness of Batteries

As per the MoP/ CEA direction given in pursuant to recommendations of the Enquiry Committee (NEW grid disturbance on 30th & 31st July, 2012), RPC’s are required to obtain from their respective Constituents the monthly certificate for healthiness of batteries, installed at 220 KV

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th Meeting of PCSC held on 26

th May, 2016 Page 4

and above voltage level Substations (for power supply to Relays, RTUs and PLCC equipment) and furnish the same to CEA/ MoP. With reference to above, the Constituents have been requested to submit the certificate on healthiness of batteries on monthly basis (i.e. status for a month shall be sent by the 7th day of the following month) to SRPC. The sought status for the month of April, 2016 has not been received from the following SR-Constituents:

TSTRANSCO, KPTCL, PED, PGCIL (SR-I & SR-II), NTPC-Ramagundam,

NTPL, CEPL & SEL

7. TSTRANSCO’s request to disable Special Protection Scheme at their 400 kV Mamidipally SS

An SPS had been implemented at 400kV Mamidipally substation in the year 2012 to avoid tripping of all 3x315MVA ICTs on overload in case of tripping of any one of the ICT’s. As per the scheme, whenever any ICT trips at 400kV Mamidipally substation, a Direct Trip signal would be generated at 400kV Mamidipally substation and trips the HV circuit breakers of 160/100 MVA, 220/132 kV Transformers at 220kV Shamshabad and 220kV Shadnagar substations to avoid tripping of remaining two ICTs at 400kV Mamidipally substation due to over loading. Now TSTRANSCO vide their mail dated 11.05.2016 informed that the daily average load on each 3x315MVA ICTs was not exceeding 230 MW for the past one year. Moreover, fourth 315 MVA ICT was taken into service on 07.01.2016. With this, even if any one of the 4x315 MVA ICTs was tripped, the remaining 3 ICTs would be able to share the available load. In view of the above, TSTRANSCO had requested for disabling/ deactivating the existing SPS scheme at 400kV Mamidipally substation to avoid tripping of PTRs at 220kV Shamshabad and 220kV Shadnagar substations as balance 3 nos. ICTs could cater to the loads in the eventuality of tripping any one of the fours ICT’s at 400kV Mamidipally substation. The above proposal of TSTRANSCO was discussed, and the forum acceded to TSTRANSCO’s request to disable/ deactivate the existing SPS t their 400 kV Mamidipally SS.

8. Special Meeting on Pending Protection Issues of M/s KPCL A special meeting was held on 3rd June, 2016 to deliberate on the pending protection issues of

M/s KPCL. The minutes of the meeting are given at Annexure-VI for kind reference. 9. Network configuration changes

As per the information furnished by SR-Constituents to the OCC forum in their 119th meeting (held on 10.05.2015; Minutes circulated on 27.05.2016), it is formed that the following configuration changes (additions/ deletions/ modifications of transmission elements) took place in the southern grid during March, 2016.

2nd Unit of M/s IL & FS Tamil Nadu Power Company Limited (ITPCL) (2x600 MW) in Tamil Nadu had declared COD from 00:00 Hours of 30.04.2016.

SR I, Power grid vide letter dated 30.04.2016 informed that consequent to successful completion of Trial Operation, the following assets under “Transmission System for Ultra

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th Meeting of PCSC held on 26

th May, 2016 Page 5

Mega Solar Park in Anantapur Dist, Andhra Pradesh – Part – A (Phase –I)” have been put under Commercial Operation w.e.f 00:00 hrs of 28th April 2016 in terms of Clause 4 of CERC (terms and Conditions of Tariff) Regulations, 2014. 1 No. 500 MVA, 400/220kV Transformer at NP Kunta Pooling Station along with

associated bays and equipment. LILO of 400 kV Kadapa (Cuddapah) – Kolar S/C line at NP Kunta Pooling Station. 2 Nos of 220 kV line bays at NP Kunta Pooling Station

220 kV D/C line from Jurala SS to Lower Jurala Hydro power of 22 ckm was commissioned on 29.04.2016 by TSTRANSCO.

220 kV SS at Dichpally in Nizamabad Dist of 1 x 160 + 2 x 100 existing MVA capacity was augmented to a capacity of 2 x 160 + 2 x 100 MVA and was commissioned on 06.04.2016 by TSTRANSCO.

220 kV SS at Bongiri in Nalgonda Dist of 2 x 100 existing MVA capacity was augmented to a capacity of 3 x100 MVA and commissioned on 16.04.2016 by TSTRANSCO.

220 kV SS at Waddekothapally in Warangal Dist of 2 x 160 + 1 x 100 MVA existing Capacity was augmented to a capacity of 3 x 160 MVA and was commissioned on 25.04.2016 by TSTRANSCO.

220 kV SS at Miryalguda in Nalgonda Dist Dist of 2 x160 + 1 x 100 existing MVA was augmented to a capacity is of 2 x 160 + 2 x 100 MVA and was commissioned on 26.04.2016 by TSTRANSCO.

220 kV SS at Renigunta in Chitoor Dist of 3 x 100 MVA was augmented to a capacity of 2 x100 + 1 x 160 MVA and was commissioned on 01.04.2016 by APTRANSCO.

220 kV SS at Chinakampally in YSR Dist of 1 x 100 MVA was augmented to a capacity of 1 x100 + 1 x 161 MVA and was commissioned on 02.04.2016 by APTRANSCO.

220 kV SS at Kondapally in Krishna Dist of 3 x100 MVA Capacity was augmented to a capacity of 2 x 100 + 1 x160 MVA and was commissioned on 25.04.2016 by APTRANSCO.

10. Instances of SPS Operation

Based on the information furnished by SRLDC, it is informed that the following instances of SPS operation took place in SR during the period 28.04.2016 – 25.05.2016.

Sl No

Date Time (hrs)

Reason Load relief obtained (MW)

AP KAR KEL TN Total

1 30-May-16 9:49 Talcher-Kolar SPS operated as pole-1

tripped 250 300 0 319 869

11. Compliance of Hon’ble CERC Orders

11.1 Petition No. 146/MP/2013 with I.A. 36/2013: Order dated 20.02.2014

Compliance of Regulations 5.2 I of the Grid Code: Issue regarding non-furnishing of FIR / Trip Analysis Report, EL, DR, etc. was also highlighted. It is pointed out that the above reports are to be submitted / uploaded on SRLDC web application within 24

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hours as mandated under IEGC / CEA Regulations.

Implementation of Phase-I and Phase-II of Protection Audit Recommendations: All the constituents are requested to submit the updated status of the compliance (those who have not completed recommendations mentioned in the Phase I and Phase II) to SRPC Secretariat at the earliest.

Compliance of Regulations 5.2 (e) & 5.2 (l) of the Grid Code and Regulation 3(1)(e) of CEA Grid Standards: The constituents are requested to strictly comply with these provisions by ensuring standard protections systems having the reliability, selectivity, speed and sensitivity to isolate the faulty equipment and protect all components from any type of faults, within the specified fault clearance time and providing protection coordination

Ensuring proper maintenance of transmission lines and adopting best O&M practices: The constituents are requested to conduct line patrolling regularly as per the SRPC transmission line patrolling guidelines (available under the menu item “All Uploads Operation Miscellaneous Transmission Line Patrolling Protocol / Guidelines for Southern Region” on SRPC website). (http://www.srpc.kar.nic.in/website/2014/operation/patrolling.pdf).

11.2 Petition No. 167/Suo- Motu/2012: Order dated 22.02.2014

The Constituents are requested to follow approved protection philosophy

ISTS licensees are requested to submit details of updated distance protection relay setting of all inter-regional lines to POSOCO & RPCs.

All SLDCs are requested to install/activate sound recording system in their control rooms within three months from the date of issue of this order.

The Constituents are requested to submit the progress of implementation to SRPC and SRLDC as specified in the Hon’ble CERC Order.

11.3 Petition No. 263/MP/2012: Order dated 19.12.2013

Constituents are requested to implement the quantum of relief by AUFR and df/dt relays by identifying additional feeders and keep them functional within one month of issuing this order.

SLDCs are also requested to map these relays on their respective SCADA system within three months of issuance of this order.

The Constituents are requested to submit the progress of implementation to SRPC and SRLDC as specified in the Hon’ble CERC Order.

11.4 APTRANSCO’s Petition No.95/MP/2015: Date of hearing 09-04-2015

It was noted in the Analysis and Decision part of the Order that:

“8. Noting the submissions of the petitioner, SRPC and SRLDC and activities initiated by the petitioner for procurement of materials required for implementation of the remarks of protecting audit, we allow time to the petitioner till 31.12.2015 for completion of our directions in Order dated 19.12.2013 in Petition No. 146/MP/2013.”

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“9. SRPC is directed to monitor the status of completion of works relating to protection audit remarks in respect of 7 nos 400 kV sub-stations and 11 nos 220 kV sub-stations of APTRANSCO, protection audit remarks in Protection Coordination Sub-Committee (PCSC) meetings and coordinate the periodic protection audit to be carried out in Southern Region after deliberation in SRPC and submit bi-monthly report to the Commission.”

11.5 TSTRANSCO’s Petition No.83/MP/2015: Order dated 14-05-2015

It was noted in the Order that:

“12. Noting the submission of the petitioner, SRLDC and SRPC and considering the actions already initiated by the petitioner for implementation of works relating to protection audit, we allow time till 31.10.2015 and 31.8.2016 for implementation of Phase-I and Phase -II works respectively. The petitioner is directed to submit affidavit confirming the completion of Phase I of protection audit remarks by 31.10.2015 and Phase-II of protection audit remarks by 31.8.2016.

13. SRPC is directed to monitor the status of completion of remarks in these substations vis-à-vis protection audit remarks in Protection Coordination Sub Committee (PCSC) meetings. SRPC is further directed to coordinate the periodic protection audit to be carried out in Southern Region after deliberation in SRPC.”

11.6 Order in Petition No. 86/MP/2014 and 374/MP/2014: Order dated 18-08-2015

The time-lines given to the various SR-Constituents for completion of Phase-I and Phase-II activities of Protection Audit Recommendations vide above Order are given below:

(A) KSEBL:

18. Noting the submission of KSEBL, SRLDC and SRPC and considering the actions already initiated by KSEBL for implementation of remarks of protection audit, we allow time till 31.12.2015 and 31.3.2016 for implementation of Phase-II works and R&M works at Idduki HEP respectively.

(B) TANTRANSCO:

21. After considering the submissions of TANTRANSCO, SRLDC and SRPC, it is noted that TANTRANSCO`s request for time till 31.5.2015 for implementation of Phase–I activities of providing numerical relays for feeder protection and Auto transformer protection is already over. We allow time till 30.6.2016 for other Phase-I activities such as provision of line VT, 5 core CT, Time synchronizing with GPS, Disturbance recorder & event logger and Phase-II activities. According to SRLDC, total implementation period is 15 to 16 months for items which involve major procurement, design changes with major site modification/civil activities. Accordingly, we allow 16 months time i.e up to 30.11.2016, for Renovation and Modernization of Singarpet, Singaperumalkoil, Salem and Tondiarpet 230 kV sub-stations from the issue of the order.

(C) NLC:

22. NLC has sought time upto 31.12.2014 and 31.3.2015 for completion of Phase-I work of Numerical Relay Retrofitting and for Phase-II works of providing second battery bank of PLCC respectively. It is noted that the completion dates for Phase-I and Phase-II of protection audit remarks as requested by NLC are already over. Therefore, no direction is required in this regard. However, we direct NLC to file a confirmation report regarding

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completion of protection audit works for Phase-I and Phase-II.

(D) KPTCL:

23. …

…

Considering the submission of KPTCL and SRLDC, we allow time to KPTCL time till 15.01.2016 for completion of Phase-I and Phase-II of protection audit remarks. No further extension shall be granted in this regard.

(E) KPCL:

24. …

…

Considering the submission of KPCL and SRLDC, we allow time to KPCL till 31.10.2015 and 31.12.2015 for completion of Phase-I for Phase-II of protection audit remarks respectively. No further extension shall be granted in this regard.

26. We direct SRPC to (a) submit status of protection audit remarks in respect of APGENCO, NTPC (SR), Talcher, Puducherry, PGCIL (SRTS I & II), MAPS and TANGEDCO, (b) monitor the status of completion of remarks of protection audit in respect of all constituents of Southern Region in Protection Coordination Sub-Committee (PCSC) meetings, and (c) to coordinate periodic protection audit to be carried out in Southern Region after deliberation in SRPC. All the constituents of Southern Region are directed to file their status with SRPC on regular basis to facilitate proper monitoring in PCSC meetings. SRPC is directed to submit bi-annually status report to the Commission confirming the completion of Phase-I, Phase-II and R&M works of protection audit remarks of the constituents of Southern Region.

12. Nomenclature for naming various files uploaded in Web based Tripping Monitoring System of SRLDC Portal

The nomenclature to be followed by the Constituents in naming various files (FIR, DR, EL, TR) corresponding to a tripping incident was brought out in the SRPC letter No. SRPC/ SE-III/ PCSC-45/ 4609 – 649 dated 26.06.2015 and in the minutes of PCSC-45 issued vide SRPC letter No. SRPC/SE-III/ PCSC-45/ 2015/ 5422-455 dated 21.07.2015. As illustrated therein, the format to be followed for the user entered part-name is given below:

Transmission Element File name to be given by the user

Transmission line SSN_DSN_line#_FT

Inter-connecting Transformer SSN_ICT#_FT

Generating Transformer SSN_GT#_FT

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Generating Unit SSN_Unit#_FT

Where, SSN = Source Station Name/ From end Station Name/ Sending end Station Name

DSN = Destination Station Name/ To end Station Name/ Receiving end Station Name

FT = File Type (FIR/ DR/ EL/ TR)

All SR-Constituents are requested to kindly intimate the above file naming nomenclature to all the concerned and ensure that it is strictly followed at all stations in their control area so that tripping analysis can be done systematically.

13. Date & Venue of the next Meeting

It is informed that the 55th PCSC meeting will be held on 29.06.2015 (Wednesday) at 10:30 hrs in the Conference Hall of SRPC, Bengaluru.

*****

Annexure-I

Annexure-I

Annexure-I

Annexure-I

Annexure-I

Annexure-I

54th PCSC meeting of SRPC

Annexure-II

Page 1 of 42

Sr. No.

Details of Event

Date &

Time Reason Remarks

Categor

y

1

Complete outage of

220kV S.P.Koil

Station of

TANTRANSCO

02-04-2016 at 17:50 hrs B-phase CT failure occurred in 220kV

MAPS-S.P.Koil line-1.. Busbar protection

got operated at SP.Koil station. All

elements except 230kV Oragadam and

230kV Kalivandapattu got tripped at

230kV S.P.Koil station. ‘Y’ phase CT and

support insulators also got damaged.

Load loss

:

GD-1

2

Complete outage of

220kV Kalamashery

Substation of KSEB

07-04-2016 at 12:31 hrs Tripping of 220kV Idukki-Kalamashery

line-1&2 led to complete outage of 220kV

Kalamassery Substation. The tripping

resulted in the outage of 110kV bus and

downstream radially fed substations

Load loss

: 400

MW GD-1

3

Complete outage of

230 kV Mywadi

substation of

TANTRANSCO

21-04-2016 at 23:47 hrs All feeders at 230 kV Mywadi S/S tripped

on operation of LBB protection as breaker

of O.K.Madapam feeder was under lockout

at Mywadi

GD-1

23-04-2016 at 10:57 Hrs 230 kV Mywadi-Pugalur line tripped on R-

Y fault. Bus bar protection got operated for

the line fault

GD-1

Details of Grid Disturbances: Annexure-II

Page 2 of 42

Complete outage of 220kV S.P.Koil Station of TANTRANSCO at

17:50 hrs on 02-04-2016

• Triggering incident : B-phase CT failure occurred in 220kV MAPS-S.P.Koil line-1.

• Details from FIR :

– Distance protection of line got operated sensing fault in zone-1.

– Bus-bar protection got operated at SP.Koil station.

– All elements except 230kV Oragadam and 230kV Kalivandapattu got tripped at 230kV S.P.Koil

station.

– ‘Y’ phase CT and support insulators also got damaged.

• Bus coupler breaker is not healthy at 230kV S.P.Koil station

Annexure-II

Page 3 of 42

Complete outage of 220kV Kalamashery Substation of KSEB at

12:31 hrs on 07-04-2016

• Antecedent condition : 220kV Kochi-Kalamasheri lines were under planned shutdown.

• Triggering incident : 220kV Kochi-Kalamasheri lines were under planned shutdown.

– Tripping of 220kV Idukki-Kalamashery line-1&2 led to complete outage of 220kV Kalamassery Substation.

– This resulted in the outage of 110kV bus and downstream radially feeding substations, 66kV bus and its downstream substations.

– Load loss : 400MW

Annexure-II

Page 4 of 42

• 220KV Idukki-Kalamashery line-1 tripped on a B-phase to earth fault in zone-1 at Kalamashery and Idukki.

• Distance protection zone-1 had operated at both ends.

• 220kV Idukki-Kalamashery line-2 tripped at Kalamassery end only due to

overloading of this feeder.

Annexure-II

Page 5 of 42

Loading on 220kV Idukki-Kalamasheri line-2 crossed the thermal limit of line.

• Points for discussion: • Status of Auto-reclose in 220kV Idukki-Kalmasheri lines

Annexure-II

Page 6 of 42

Complete outage of 230 kV Mywadi substation of

TANTRANSCO

Annexure-II

Page 7 of 42

Complete outage of 230 kV Mywadi substation of

TANTRANSCO

• Tripping at 23:47 hrs 21-04-2016

– Triggering incident : R-phase to earth fault in 230 kV Mywadi - Othakal mandapam line.

– AR operated and breaker was holding at 230 kV OKMandapam S/s.

– O.K.Madapam feeder was under lockout at Mywadi

– All feeders at 230 kV Mywadi SS (Anikadavu, Udumalpet-1 & 2, Kadamparai-1 & 2, Ponnapuram-1 & 2, Pugalur, Sembatty, 400/230 kV ICT-1,2 & 3 (PGCIL)) tripped on operation of LBB protection.

Annexure-II

Page 8 of 42

• Tripping at 10:57hrs on 23-04-2016

– Triggering incident : 230 kV Mywadi-Pugalur line tripped on R-Y fault.

– Mal-operation of Bus bar protection during line fault.

– All feeders at 230 kV Mywadi SS (Anikadavu, Udumalpet-1 & 2, Kadamparai-1 & 2, Ponnapuram-1 & 2, OKMandapam, Sembatty, 400/230 kV ICT-1,2 & 3 (PGCIL)) tripped on operation of bus bar protection

Annexure-II

Page 9 of 42

• Line tripped on R-phase to earth.

• LBB of tie breaker got operated at Nellore (AP) which resulted in tripping of 400kV Vijayawada-Nellore line and 400/220kV ICT-2 at Nellore (AP).

• Reason for LBB operation and remedial actions taken may be furnished

Tripping of 400kV Vijayawada-Nellore(AP) line-1 and ICT-2

at 13:52 Hrs on 03-04-2016

Vijayawada-1

Nellore (AP)

ICT-2

Annexure-II

Page 10 of 42

• Triggering incident : Failure of Y-Phase CT failure at Mamidipally station in 400kV Shankarapalli feeder.

• Protection operated : – Zone-1 at Mamidipally

– Zone-2, Carrier aided trip at Shankarpalli

• Mamidapalli end DR not furnished

Tripping of 400kV Shankarapalli-Mamidapalli line

at 00:03Hrs on 04-04-2016

Annexure-II

Page 11 of 42

• Tripping of 400kV Nellore-Sriperambadur line-1 – R-phase to earth fault

– Auto reclose attempt was unsuccessful due to persistent fault

– Voltage observed in Y&B phases in sriperambadur DR after AR attempt.

• Tripping of 400kV Sriperambadur-S.V.Chatram line – Line tripped at Sriperambadur end only on operation of over current protection.

– Suspected Mal-operation

Tripping of 400kV Sriperambadur-SV.Chartam and 400kV Nellore-

Sriperambadur line-1 at 00:11 Hrs on 05-04-2016

Annexure-II

Page 12 of 42

• Line tripped on operation of Backup impedance protection of line reactor.

• Direct trip was received at Mahboobnagar end. DR not furnished

• Reason for operation of Backup impedance may be furnished

Tripping of Raichur TPS-Mahboobnagar line at 10:23Hrs on

05-04-2016

Annexure-II

Page 13 of 42

• During both tripping, B-phase to earth fault had occurred in line.

• At Hassan end breakers tripped after Zone-2 time i.e. 350 ms and protection did trip instantaneously on Carrier aided tripping.

Tripping of 400kV Hassan-UPCL line-2 at 12:55Hrs and 13:32 Hrs

on 07-04-2016

Annexure-II

Page 14 of 42

• Triggering incident : – Failure of 110kV Y & B phase of BUS I PT

– Bus bar protection not available for 110kV Bus

– 230/110kV ICT- 1,2, & 3 tripped on operation of Back up over current protection and all 110

kV tie feeders tripped from remote ends on Z2 operation.

• Load loss : 335 MW.

Tripping of 110kV bus at 230/110 kV Ingur substation

at 15:36 Hrs on 08-04-2016

Annexure-II

Page 15 of 42

Annexure-II

Page 16 of 42

• 400kV Simhadri-Gajuwaka line-2 – R-phase to earth fault - Insulator de-capping

– Line tripped in zone-2 at Simhadiri end.

– Attempt for auto-reclose could not be established from DR and EL of Gazuwaka station.

– Pole discrepancy was observed for Main breaker (1352) of Gajuwaka-Simhadri line-2 at Gazuwaka end.

• 400kV Vijayawada-Gajuwaka line also got tripped during the incident at Gazuwaka end only.

• Points for discussion : – Failure of Carrier aided tripping at Simhadiri

– Tripping of Vijayawada-Gazuwaka line

Tripping of 400kV Simhadri-Gajuwaka line-2 and 400kV Vijayawada-Gazuwaka

line at 04:21 Hrs on 10-04-2016

Annexure-II

Page 17 of 42

• Line tripped on a B-phase to earth fault and auto-reclose attempt was unsuccessful due to persistent fault.

• Running Unit-1 at NTPL got tripped on low forward power

Tripping of 400kV Coastal-Tuticorin PS line and Unit-1 at NTPL at

07:05 Hrs on 11-04-2016

94 KM

61 KM

36 KM 48 KM

NTPL TUTICORIN PS

CEPL

MADURAI

Annexure-II

Page 18 of 42

NTPL

COASTAL

TUTICORIN PS

MADURAI

CoastalUnit B-phase current

Annexure-II

Page 19 of 42

• Y pole breaker of Tie breaker of Unit-4 at RTPS failed.

• Unit-4 got tripped on operation of Generator Differential, Reverse power & LBB protection.

• Operation of LBB protection led to tripping of BUS-2 at RTPS

• Points for discussion: – Status of bus coupler breaker

Tripping of 400kV Raichur TPS Bus-2 at 21:12Hrs on 13-04-2016

Annexure-II

Page 20 of 42

• Antecedent : At 18:33hrs, – IDMT E/f & subsequent operation of BFR protection of CWC-23 filter of east side filter of pole-1

– Tracking across Y phase grading capacitor

• At 18:58 hrs – IDMT E/f & subsequent operation of BFR protection of CWC-33 filter of east side filter of pole-1

– Tracking across Y phase grading capacitor

– Pole-1 went to standby mode due to non-availability of South filter.

Tripping of HVDC GAJUWAKA POLE 1

at 18:58 Hrs on 14-04-2016

Annexure-II

Page 21 of 42

• HVDC Talcher-Kolar Pole-1 tripped at Talcher end due to tripping of valve cooling system of pole-1 as fire has occurred in Valve Cooling UPS System.

Tripping of HVDC TALCHER - KOLAR POLE 1

at 18:43 Hrs on 14-04-2016

SPS operation details:

Annexure-II

Page 22 of 42

• Pole2 tripped on due to suspected maloperation of SF6 Gas Pressure Monitor of star bushing of Y-phase transformer.

Tripping of HVDC TALCHER - KOLAR POLE 2

at 19:44 Hrs on 14-04-2016

SPS operation details:

Annexure-II

Page 23 of 42

• Poles tripped due to loss of East bus voltage due to disturbance in Eastern region.

Tripping of HVDC GAJUWAKA POLE-1&2 at 12:23 Hrs on

15-04-2016

Annexure-II

Page 24 of 42

• During testing of retrofitted distance protection in 400kV Raichur-2 feeder, LBB protection trip DC got extended to Bus trip.

• This resulted in tripping of 220kV bus at RTPS and subsequently tripping of all connected 220kV elements.

• Unit-4 which is connected to 400kV Bus got tripped due to tripping of Station Utility Transformer

• Generation loss was around 760 MW.

Tripping of 220kV elements and Units1,2,3&4 at Raichur TPS at

15:36 Hrs on 15-04-2016

Annexure-II

Page 25 of 42

• East Converter Transformer Y-phase OLTC Tap gone out of step as compared to R and Y-Phase

• “Y” Phase transformer remained stuck at position 15, “R” and “Y” tap position are at 13.

• AC MCB of OLTC Motor of Y-phase got tripped in OLTC cubicle

• Remedial actions taken to avoid repetition of event may be furnished

Tripping of HVDC GAJUWAKA POLE 1 at 10:18 Hrs on 16-04-2016

Annexure-II

Page 26 of 42

• ICT tripped on operation on operation of Bus Reactor TEED protection.

• Dip observed in B-phase voltage in DR

• Findings and remedial actions may be shared with PSC

Tripping of ICT-2 at Cudappah station at 21:14 Hrs on 20-04-2016

Annexure-II

Page 27 of 42

• Tripping at 1:40 hrs on 21-04-2016 – Line tripped on direct trip receive at Satenapalli end.

– over-volatage start was observed in DR of Srisailam

• Tripping at 13:40 hrs on 21-04-2016 – R-Ph to earth fault had occurred in line. Line did not auto-reclose

– Direct trip receive was observed in DR of Sattenapalli and Srisailam.

Tripping of 400kV Sattenapalli-Srisailam line-2 at 01:40 Hrs on

21-04-2016

Annexure-II

Page 28 of 42

Tripping of HVDC GAJUWAKA POLE-1&2 at 18:16 Hrs on

22-04-2016

• 400kV Jeypore-Gazuwaka line-1&2 and HVDC Gazuwaka pole-1&2 got tripped during the incident.

• Details from FIR :

• HVDC pole-2 got blocked due to loss of east bus voltage from pole-1 east bus. • HVDC pole-1 got blocked due to loss of all filters of east side. • 400kV Jeypore-Gazuwaka line-1 tripped on direct trip receive and 400kV Jeypore-

Gazuwaka line-2 tripped on BFR operation.

Annexure-II

Page 29 of 42

• Two faults were observed through PMU data.

• First dip in R and B phase for 200ms and 2nd dip 500ms after 1st fault.

• 2nd dip was prominent in B-phase and 240ms.

Annexure-II

Page 30 of 42

Observation from DR of 400kV Jeypore-Gazuwaka line-1 Annexure-II

Page 31 of 42

Annexure-II

Page 32 of 42

• It can be observed that R-phase to earth fault had occurred in 400kV Jeypore-Gazuwaka line-1. Breakers at Gazuwaka got tripped on direct trip receive.

• Distance protection zone-4 operation observed at Gazuwaka.

• Current is observed in R-phase even after opening of breakers at Gazuwaka.

LBB protection got operated at Gazuwaka after 250ms. Direct trip sent was not observed in digital channel.

• Distance protection operation observed after 600ms. Fault current observed in B-phase for 200 ms.

• Voltage in B-phase is observed for 800ms and in B-phase for 600ms.

Annexure-II

Page 33 of 42

Observation from DR of 400kV Jeypore-Gazuwaka line-2 Annexure-II

Page 34 of 42

Z4 operation observed and Main-1 carrier receive observed. It appears that Jeypore end relay has sensed the fault in R-phase and tripped the breaker.

In DR there is absence of R-phase voltage. R-phase voltage re-appears after 200ms. Main breaker at Gazuwaka got tripped after 500ms on Z4 operation and Tie CB got tripped after

750 ms due operation of LBB protection. Main-2 carrier receive also observed.

Annexure-II

Page 35 of 42

Points for further investigation: Reason for LBB operation for Main- CB (CWD20-Q51) of 400kV Jeypore-Gazuwaka line-1, Tie breaker CW20 Q50, and Main breaker (CWD20-Q52) of filters CWC-23,24&25. Over-reach of relay at Jeypore end for fault in line-1.

Annexure-II

Page 36 of 42

• Details from FIR – Pole-1 blocked due to operation of BFR of south side filter CWC-36.

– Pole-2 tripped on loss of East side voltage from HVDC pole-1due to tripping of East bus-1 extension on differential trip.

Tripping of HVDC GAJUWAKA POLE-1 at 20:44 Hrs and pole-2 at

21:01 Hrs on 22-04-2016

Annexure-II

Page 37 of 42

• Line tripped during disturbance at 230kV Myavdi TNEB SS as Main-I relay picked up in zone- 3

• Findings and remedial actions may be shared with PCSC

Tripping of 400kV Madurai-Udumalpet line at 10:57 Hrs on

23-04-2016

Annexure-II

Page 38 of 42

Tripping of 400kV Ramagundam-Chandrapur line-1&2 at 19:26hrs on 04-05-2016

• Tripping of Ramagundam-Chandrapur line-1 – B-phase to earth fault in line at 19:16 hrs

– Line auto-reclosed at Chandrapur and did not auto-reclose at Ramagundam

– Pole discrepancy was observed in E.L

• Tripping of Ramagundam-Chandrapur line-2 – B-phase to earth fault in line at 19:26:hrs

– Ramagundam end tried to auto-reclose

– 3 phase trip at chandrapur both ends as line-1 had already tripped.

– Bhadrawati pole-1&2 tripped due to loss of south bus voltage

Annexure-II

Page 39 of 42

Annexure-II

Page 40 of 42

Sr.

No. Element

Date &

Time Reason

1

Tripping of 400kV NCTPS-Vallur

line-2

02-04-2016 at 2:09 hrs line tripped on a R-phase to earth fault. Line

auto-reclosed at NCTPS end and tripped at

Vallur end.

2

Tripping of 230kV Yerandahalli-

Hosur line

03-04-2016 at 12:48 hrs Line tripped on a R-phase to earth fault. Auto-

reclose was successful at Hosur. A/r not

available at Yerandahalli.

3

Tripping of 400kV Kalivandapattu-

Vallur line

10-04-2016 at 14:59 hrs R-phase to earth fault had occurred in line.

Auto reclose attempt or unsuccessful auto-

reclose could not be established from

provided DR/ EL.

4

Tripping of 400kV Vijayawada-

Nellore line-2

11-04-2016 at 6:43 hrs Line tripped on a B-phase to earth fault.

Attempt for Auto-reclose or unsuccessful

auto-reclose could not be established could

not be established from DR and EL furnished

5

Tripping of 400kV Coastal-NTPL

line

18-04-2016 at 4:25 hrs Line tripped on a Y-phase to earth fault. Line

auto-reclosed at Coastal end and did not

reclose at NTPL and Y&B pole tripped on

pole-discrepancy

6

Tripping of 400kV Hoody-

Neelamangala line-2

23-04-2016 at 13:22 hrs line tripped on a B-phase to earth fault.

Attempt for A/r or un-successful A/r could not

be established from DR

8

Tripping of 400kV Ambewadi-Ponda

line-1

26-04-2016 at 12:13 hrs FIR line tripped on a B-phase to earth fault.

DR was not available for the event. Auto-

reclose not enabled for line.

Failure or non-operation of Auto reclose during transient fault Annexure-II

Page 41 of 42

Sr.

No.

Details of Event Date &

Time Reason Remarks Category

1

Tripping of 400kV

Khammam-

Kalpakka line-2

22-04-2016

at 12:22 hrs

R line tripped at Kalpaka end

only on receipt of Direct trip &

holding from Khammam end

2

Tripping of 400kV

Ghanapur-

Mamidapalli line

30-04-2016

at 16:40 hrs

line tripped at Mamidipally end

only on direct trip received from

Ghanapur end

Lines tripping due to tripping at one end /PLCC mal-operation Annexure-II

Page 42 of 42

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 1/37

Analysis of Grid Occurrences - 54

I. Details of Grid Disturbances:

Sl. No.

Details of Event Date & Time Reason Remarks Category

1

Complete outage of 230 kV S.P.Koil Station of TANTRANSCO

02-04-2016 at 17:08 hrs

B-phase CT failure occurred in 230 kV S.P.Koil - MAPS line-1. Busbar protection got operated at SP.Koil station. All elements except 230kV Oragadam and 230kV Kalivandapattu got tripped at 230kV S.P.Koil station. ‘Y’ phase CT and support insulators also got damaged.

Gen Loss: NIL Load loss: NIL

GD-1

SLD: The Single Line Diagram of 230 kV SP Koil SS as provided by TANTRANSCO is attached at the end. Triggering incident was the bursting of B-phase CT at SP Koil end on 230kV S.P.Koil - MAPS line-1. SP Koil – MAPS line-1: SP Koil SS (TANTRANSCO) end:

As per FIR/TR, line tripped at 17:08 hrs on B-E fault due to DPR, Z1 operation. As per DR/EL, line tripped at 18:07:44.531 hrs on B-E fault due to DPR, Z1 operation. It was stated in TR that in 230kV Kalpakkam #1, ‘B’ Phase CT got bursted and 230kV Kalpakkam-1# got tripped in

Zone-1; Carrier was sent to the remote end, and simultaneously 230KV Busbar protection acted. Also adjacent ‘Y’ ph. CT and AB switch supporting insulators got damaged.

Time-sync of DR & EL needed to be ensured. MAPS (NPCIL) end:

As per FIR, line tripped (in 3-ph) at 17:10 hrs due to DPR, Z2 operation (42.83 km from MAPS end). As per FIR, Main-1 gave 3-ph trip; Main-2 gave B-ph trip.

DR & EL not furnished. Time-sync of DR & EL needed to be checked. SP Koil – MAPS line-2: SP Koil SS (TANTRANSCO) end:

As per FIR/TR, line tripped at 17:08 hrs due to BBP operation. DR/EL showing occurrence of BBP operation not furnished. MAPS end:

As per FIR, line tripped (in 3-ph) at 17:10 hrs on B-E fault due to DPR operation. As per FIR, Main-1 gave earth fault trip; Main-2 gave B-ph trip. DR & EL not furnished. PMU Plot for the triggering event:

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 2/37

SRPC/ SRLDC:

From the above PMU plot, there was no delay in clearing of the fault; as such Zone-2 operation at MAPS end on SP Koil – MAPS line-1 was not correct.

Even otherwise also, the fact that SP Koil – MAPS line-1 tripped at MAPS end in Zone-2 even though the carrier was sent from SP Koil end implied that Carrier Aided Trip had not taken place at MAPS, which in turn pointed to unhealthiness of PLCC Channels/ communication at MAPS end.

Further, since BBP had operated at SP Koil SS, tripping of SP Koil – MAPS line-2 at MAPS end was also not in order. It was also noted that for both the line trippings at MAPS end, Main-1 & Main-2 of respective lines seemed to have

operated on different kind of protections, which again pointed to the faulty operation of either Main-1 or Main-2 or both.

The operation of E/f relay at MAPS end on SP Koil – MAPS line-2 was not in order, for the remote (SP Koil) end had already tripped due to BBP operation. Moreover, it being a back-up protection, which comes into picture with time delay, could not act instantaneously. Hence back-up E/f protection settings needed to be checked.

The main handicap in analyzing the above trippings at MAPS end was the non-furnishing of respective DR’s & EL’s by MAPS. As such, the events shall be got analyzed thoroughly by MAPS with focus on the correctness of the settings of Main-I & Main-II relays (for primary & back-up protections) on both the lines.

To this, MAPS representative assured that the events would be analyzed thoroughly, and a detailed report would be furnished.

When MAPS representative informed that E/f protection had been set to operate on DMT, SRPC/ SRLDC clarified that both O/C and E/f protections should be set for normal inverse operation; only high-set should be set to operate with DMT, typically 50 msec.

When enquired about providing A/R operation at MAPS end on all 230 kV emanating lines as agreed in 19.05.2016 meeting, MAPS representative informed the same was under progress, and would be implemented soon. To this, SRPC/ SRLDC requested MAPS to furnish the time-line of providing A/R on all 230 kV (four in no.) lines, and complete the same by June, 2016 as agreed in the referred meeting.

As per TANTRANSCO Report dated 25.04.2016:

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 3/37

To an enquiry by ED, SRLDC, whether R& M works of 230 kV SP Koil SS were covered as part Phase-I & Phase-II

works, TANTRANSCO clarified that they were being pursued separately along with three other stations, and

include works such as commissioning of numerical bus-bar protection, providing double-bus operation, control

room shifting, etc., and would be completed in six months time.

In this context, TANTRANSCO was reminded of nearing dead-lines of Phase-I & Phase-II Protection Audit works

(30.06.2016), and was requested to take suitable action.

Recommendations:

MAPS to furnish a detailed report on the tripping of SP Koil – MAPS lines 1 & 2 at MAPS end with focus on the correctness of the settings of Main-I & Main-II relays (for primary & back-up protections) on both the lines.

MAPS to take steps to provide down-loading facility for DR & EL from Main-I & Main-II relays on all 230 kV lines emanating from MAPS.

MAPS, in co-ordination with SP Koil, to carry out PLCC end-to-end testing, on SP Koil – MAPS lines 1 & 2, and ensure healthiness of PLCC communication & carrier-aided protection.

MAPS to put in service Auto-Reclosure feature on all four 230 kV lines emanating from MAPS by June, 2016.

2

Complete outage of 220 kV Kalamassery Substation of KSEB

07-04-2016 at 12:31 hrs

Tripping of 220kV Idukki-Kalamassery line-1&2 led to complete outage of 220kV Kalamassery Substation. The tripping resulted in the outage of 110kV bus and downstream radially fed substations

Load loss: 400 MW

GD-1

SLD:

The Single Line Diagram of 220 kV Kalamassery SS as provided by KSEB is attached at the end. Kalamassery – Idukki line-1: Idukki (KSEB) end:

As per FIR/DR/EL/TR, the line tripped (in 3-ph) at 12:37:20.722 hrs on B-E fault due to DPR, Z1 operation. It was stated in TR that A/R was kept out of service due to commissioning of new relays and pending completion of

related wiring works. Kalamassery (KSEB) end:

As per FIR/DR/EL/TR, the line tripped (in 3-ph) at 12:32:00.407 hrs on B-E fault due to DPR, Z1 operation. It was stated in TR that A/R was kept out of service due to DC leakage at the time of tripping.

Kalamassery – Idukki line-2: Idukki (KSEB) end:

As per FIR, line was kept holding from Idukki end. Kalamassery (KSEB) end:

As per FIR/DR/EL/TR, the line tripped (in 3-ph) at 12:37:25.046 hrs due to operation of Over Current protection.

As generators connected on the 110 kV side had already been kept out of service, above tripping led to outage of 110kV bus and downstream radially fed substations.

Time-sync between Kalamassery and Idukki needed to be ensured.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 4/37

As per KSEB report dated 04.05.2016:

KSEB also informed that A/R at Idukki end would be put into service within two weeks. SRLDC:

Simultaneous outage for two out of the four lines (220 kV Kalamassery – Cochin lines 1 & 2 in the present case) should not have been given. However, in the event of absolute requirement of the same, proper load management should be resorted to avoid over-loading of the only remaining line, if one of the balance two lines gets tripped.

KSEB concurred with the above suggestion, and assured that the same would be taken care of in future trippings.

3

Complete outage of 230 kV Mywadi substation of TANTRANSCO

21-04-2016 at 23:47 hrs

All feeders at 230 kV Mywadi S/S tripped on operation of LBB protection as breaker of O.K.Madapam feeder was under lockout at Mywadi

GD-1

23-04-2016 at 10:57 Hrs

230 kV Mywadi-Pugalur line tripped on R-Y fault. Bus bar protection got operated for the line fault.

GD-1

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 5/37

SLD:

The Single Line Diagram of 230 kV Mywadi SS as provided by TANTRANSCO is attached at the end. Outage on 21.04.2016: 230 kV Mywadi –OK Mandapam S/C line: OK Mandapam (TANTRANSCO) end: FIR/DR/EL/TR not furnished.

However as per TR of Mywadi end, A/R at OK Mandapam was stated to be successful. Mywadi (TANTRANSSCO) end:

As per FIR/TR, line tripped at 23:47 hrs due to LBB operation. It was stated that R-E fault occurred on Mywadi – OK Mandapam feeder, and DPR, Z1 operated. But due to delay in opening time of 230 kV OKM feeder, LBB protection operated and tripped all other feeders connected to 230 kV Mywadi SS.

From DR/EL, a fault was observed in R-ph at 23:43:11.353 hrs, and all phase currents have become zero after 300 msec from the instant of occurrence of fault. And the three poles of the breaker got opened after 50 more msec. (i.e., 350 msec from the instant of fault occurrence).

400/ 230 kV ICT-1&2&3 trippings at 230 kV Mywadi SS of TANTRANSCO:

As per FIR/EL/TR, ICT-1&2&3 tripped at 23:47:32.121 hrs on LV side due to operation of LBB protection at 230 kV Mywadi SS.

It was stated in TR that all other feeders at 230 kV Mywadi SS (Anikadavu, Udumalpet-1 & 2, Kadamparai-1 & 2, Ponnapuram-1 & 2, Pugalur, Sembatty, 400/230 kV ICT-1,2 & 3 (PGCIL)) also got tripped on operation of LBB protection.

As per TANTRANSCO Report dated 23.05.2016:

Outage on 23.04.2016: 230 kV Mywadi-Pugalur S/C line: Mywadi (TANTRANSCO) end:

As per FIR/TR, the R-ph jumper of the Wave-Trap got opened due to melting of clamp. Lenz's phenomena sustained the current flow, and caused the formation of arc which is within the arcing distance of 'Y' phase ultimately resulting into 'R' & 'Y' phase fault. The fault current was about 23 KA.

For this fault, it was observed from DR that the line tripped (in 3-ph) at 11:53:29.534 hrs due to DPR, Z1 operation

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 6/37

from Myvadi end. However, for this through fault, BBP protection also operated and resulted in tripping of all feeders at 230 kV Mywadi SS (Anikadavu, Udumalpet-1 & 2, Kadamparai-1 & 2, Ponnapuram-1 & 2, OKMandapam, Sembatty, 400/230 kV ICT-1,2 & 3 (PGCIL)).

Pugalur (TANTRANSCO) end:

FIR/DR/EL/TR not furnished.

However, it was stated in TR of Mywadi SS that opening of the R-ph jumper of the Wave trap at Mywadi end caused attenuation of PLCC signal at Pugalur end, and resulted in operation of DPR protection in Zone 2.

400/ 230 kV ICT-1&2&3 trippings at 230 kV Mywadi SS of TANTRANSCO: As per FIR/EL/TR, ICT-1&2&3 tripped at 10:57:03.138 hrs on LV side due to operation of LBB protection at 230 kV

Mywadi SS. It was stated in TR that all other feeders at 230 kV Mywadi SS (Anikadavu, Udumalpet-1 & 2, Kadamparai-1 & 2,

Ponnapuram-1 & 2, Pugalur, Sembatty, 400/230 kV ICT-1,2 & 3 (PGCIL)) also got tripped on operation of LBB protection

Time-sync of line feeders’ relays and ICT’s relays at Mywadi SS needed to be ensured. As per TANTRANSCO Report dated 23.05.2016:

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 7/37

In view of the imminent onset of the wind season, ED, SRLDC enquired about the status of commissioning of 230 kV Numerical Busbar protection at 230 kV Mywadi SS, to which TANTRANSCO replied/ assured that the works, which were under progress, were directly being monitored by their Chief Engineer (P&C), and would be completed in 15 days time.

400 kV Madurai – Udumalpet S/C line: Udumalpet (PGCIL-SR2) end:

As per FIR, the line was kept holding Madurai (PGCIL-SR2) end: As per FIR/EL/TR, the line tripped (in 3-ph) at 10:57:03.045 hrs on R-Y fault due to DPR, Z3 operation.

From DR, this event (Z3-trip) seemed to have occurred at 11:57:03.044 hrs. Also Z3-trip happened almost instantaneously with the occurrence of R-Y fault. However, CB’s (152 & 252) were observed to be in CLOSED condition.

Time sync of DR & EL at 400 kV Madurai SS of PCIL (SR-II) needed to be ensured. PGCIL (SR-II):

The instantaneous Z3 trip was given by the newly commissioned Main-II (Micom P44) relay. Upon investigation with the help of OEM, they found that due to some additional/ wrong PSL logics, the relay was configured to give instantaneous trip in case of L-L faults.

Remedial action: The wrong/ additional PSL logics responsible for instantaneous trip in case of L-L faults had been removed.

On this, KSEB remarked that commissioning engineers should be properly instructed to disable all old settings while configuring relays with new settings.

KPTCL mentioned that not only during commissioning, even while undertaking testing activities also due care should be taken to disable/ enable requisite/ appropriate protections.

4

Tripping of Nagjheri Generators

14-04-2016 at 12:29 hrs

220 kV Nagjheri - Bidnal line tripped on B-E fault at 12:28 Hrs. At the same time, five running generating units (1, 2, 3, 4 & 6) at Nagjheri tripped on operation of Generator Transformer’s back-up Over Current & Earth Fault protection.

Gen. Loss: 640 MW

GD-1

SLD:

The Single Line Diagram of 220 kV Nagjheri PH as provided by KPCL is attached at the end. 220 kV Nagjheri – Bidnal S/C line: Nagjheri (KPCL) end:

FIR/DR/EL/TR not furnished. However, as per FIR of Bidnal, Nagjheri end tripped at 12:29 hrs on B-E fault due to DPR, Z2 operation (3.2 kA, 91

km from Nagjheri end) Bidnal (KPTCL) end:

As per FIR, the line tripped at 12:29 hrs due to DEFR operation. It was stated in FIR that as the line tripped on B/U protection (which is an electro-mechanical relay), DR & EL’s

were not available. KPTCL: At Bidnal, line tripped on DEFR due to suspected high resistive fault.

Remedial action: In the SEL relay, Mho characteristics had been previously selected for E/F protection. Now as remedial action,

Quadrilateral characteristics were selected for DEFR protection. Further, the resistive reach in Nagzari line distance relay at Bidnal end had been reviewed and revised. Action would be taken to trigger DR in numerical distance relay for b/u protection operation also.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 8/37

Outage of 220 kV Nagjheri PH of KPCL: SRPC/ SRLDC: It was noted that the various tripping files (FIR/DR/EL/TR) uploaded under Sender and Receiver sections in

SRLDC web portal were not related to the outage of 220 kV Nagjheri PH of KPCL on 14.04.2016 at 12:29 hrs. For example, the following can be noted from the various tripping files uploaded: As per SENDER-FIR, Nagjheri – Hubli line-2 tripped at 18:18 hrs on B-E fault due to DPR, Z1 operation. (It was

also stated that only Unit-1 was in service at the time of occurrence of this fault). As per SENDER-EL/SENDER-TR, Nagjheri – Ambewadi line-2 tripped at 15:02 hrs on B-E fault due to DPR, Z1

operation. (It was also stated that all Units except Unit-2 were in service at the time of occurrence of this fault).

The SENDER-DR pertains to Nagjheri – Ambewadi line-2 for an event on 13.04.2020 at 15:02:53.416 hrs. Type of fault was not shown. (DR not in order).

In place of RECEIVER-FIR, a DR was uploaded as per which Nagjheri – Hubli line-2 tripped at 18:18 hrs on B-E fault.

As per RECEIVER-TR/ RECEIVER-DR/ RECEIVER-EL, Nagjheri – Bidnal line tripped at 12:29:49.356hrs on B-E fault due to DPR, Z2 operation (91 km). (It was also stated in TR that all Units except Unit-5 were in service at the time of occurrence of this fault. Further, all in-service Units were stated to be tripped on operation of Generator Transformer’s back-up Over Current & Earth Fault protection.)

Thus KPCL, in gross violation of IEGC Regulation 5.2 (r), had not furnished any of the relevant tripping files pertaining to the event.

Further, operation of Generator Transformer’s back-up Over Current & Earth Fault (high-set) protection was not in order, for the fault current was stated to be 3.2 kA. Accordingly, there was a need to revise the settings of GT’s back-up O/C and E/F protections considering their individual contribution to solid bus fault at 220 kV bus of Nagjheri PH.

KPCL:

To this, KPCL informed that they had revised GT’s back-up protection settings in the recent past only from 5A to 7.5 A. However, they would re-check the adopted settings, and revise accordingly.

On this, KSEB suggested to keep appropriate time delay for high-set operation of GT’s transformer back-up protections.

Upon an enquiry by SRLDC as to whether SPS in place at Nagjheri operated during the event, KPCL replied that as it was a case of instantaneous high-set operation, GT’s were tripped even before the SPS could act.

Recommendations:

KPCL to revise the settings of GT’s back-up O/C and E/F protections considering their individual contribution to solid bus fault at 220 kV bus of Nagjheri PH.

KPCL to upload/ make available various tripping files (FIR/DR/EL/TR) for all tripping involving their stations in compliance of IEGC Regulation 5.2 (r).

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 9/37

II. Details of Grid incidents:

Sl. No.

Details of Event Date & Time Reason Category

1

Tripping of 400 kV Vijayawada - Nellore (AP) line-1 and ICT-2 at Nellore(AP)

03-04-2016 at 13:52 hrs

Line tripped on R-phase to earth. LBB of tie breaker got operated at Nellore (AP) which resulted in tripping of 400kV Vijayawada-Nellore line-1 and 400/220kV ICT-2 at Nellore (AP)

GI-2

At Nellore-AP SS of APTRANSCO, Nellore – Vijayawada line-1 and ICT-2 are in the same diameter.

400 kV Vijayawada-Nellore (AP) line-1 Nellore-AP (APTRANSCO) end:

As per FIR/DR/EL, line tripped at 13:52:31.758 hrs on R-E fault due to DPR, Z1 operation. From EL, the following observations could be made: DT was sent to Vijayawada end at 13:52:31.758 hrs Main-CB R-ph pole and Tie-CB all three poles got opened simultaneously at 13:52:31.801 hrs ICT-2 HV & LV breakers tripped at 13:52:31.995 hrs due to operation of Group A/B protection

From above, it can be seen that no LBB operation for Tie-CB took place. Vijayawada (PGCIL-SR1) end: As per FIR/TR, the line tripped at 13:52 hrs on R-E fault.

EL not furnished. (EL furnished pertained to Nellore – VTPS line at Nellore end) From DR, it was observed that the line tripped (in R-ph) at 13:52:31.781 hrs on R-E fault due to DPR, Z2 (CAT)

operation. However within 25 msec, DT was received due to which the other poles (Y-ph & B-ph) of the Main-CB also got opened.

400/220 kV ICT-2 tripping:

As per FIR/EL, ICT-2 tripped at 13:52:31.995 hrs due to operation of Group A/B protection APTRANSCO:

There was no actual LBB operation of the Tie-CB during the incident. However, the auxiliary LBB relay for the Tie-CB, ABB RXIG 24 relay, had mal-operated during the event resulting in opening of adjacent Main-CB’s and DT sending to the remote (Vijayawada) end.

Remedial action: The faulty auxiliary LBB relay, ABB RXIG 24, had been replaced with spare.

2 Tripping of 400kV Shankarapalli - Mamidapalli line

04-04-2016 at 00:03 hrs

Y-Phase CT failure had occurred in 400kV Shankarapalli-Mamidapalli line at Mamidipally end.

GI-2

Mamidipally (TSTRANSCO) end:

As per FIR, line tripped at 00:03 hrs due to DPR, Z1 operation. It was stated that Y-Phase feeder CT got blasted at Mamidipally.

DR/EL/TR not furnished. Shankarapally (TSTRANSCO) end: As per FIR, line tripped at 00:03 hrs due to DPR, Z2 operation. It was stated that Y-Phase feeder CT got blasted at

Mamidipally.

As per DR/EL, line tripped (in Y-ph) at 00:01:48.810 hrs due to DPR, Z2 (CAT) operation, and tried to auto-reclose after 650 msec, but tripped in 3-ph due to persistent fault.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 10/37

TSTRANSCO:

Replacement of existing Main-I & Main-II relays with numerical relays was under progress and would be completed by end of June, 2016, after which time DR & EL’s would be furnished without fail.

When mentioned that A/R dead-time was kept at 650 msec instead of 1 sec, TSTRANSCO assured that it would be corrected.

When pointed out by SRLDC that a marked dip in R-ph voltage was observed from PMU plots at the time of auto-reclosing, TSTRANSCO replied that due to bursting of Y-ph CT, smoke & oil spread to R-ph, and created a temporary R-ph fault also, due to which the original Y-ph fault effectively got converted into R-Y fault at the time of auto-reclosing.

Remedial action: The failed Y-ph CT was replaced with spare.

Recommendations:

TSTRANSCO to revise A/R dead-time on 400 kV Shankarapalli – Mamidipalli to 1 sec at both ends. TSTRANSCO to furnish Equipment Failure Report of Y-ph CT blast to CEA with a copy marked to SRPC.

3

Tripping of 400kV Sriperambudur - SV.Chartam and 400kV Nellore-Sriperambudur line-1

05-04-2016 at 00:11 hrs

400kV Nellore-Sriperambudur line-1 tripped on a R-phase to earth fault. 400kV Sriperambudur-S.V.Chatram line tripped at Sriperambudur end only on operation of over current protection

GI-2

400kV Nellore (PG) - Sriperambudur line-1 Nellore (PGCIL-SR2) end: As per FIR/DR/TR, the line tripped (in R-ph) at 00:10:18.280 hrs on R-E fault due to DPR, Z2 (CAT) operation, and

tried to auto-reclosed after 1 sec; but tripped in 3-ph due to persistent fault. EL furnished was irrelevant as it contained events starting from 00:12:18.300 hrs Sriperambudur (PGCIL-SR2) end:

As per FIR/DR/TR, the line tripped (in R-ph) at 00:11:22.376 hrs on R-E fault due to DPR, Z1 operation, and tried to auto-reclose after 1 sec; but tripped in R-ph only (for Main-CB) and in 3-ph (for Tie-CB) due to persistent fault.

Y-ph and B-ph poles of the Main-CB continued to be in CLOSED condition. From EL (which differs from DR in time-sync by 1 .2 sec), it was observed that PDR had operated after 3.8 sec (from the instant of Main-CB opening at 00:11:22.376 hrs) to open Y-ph and B-ph poles of the Main-CB.

400kV Sriperambadur-SV.Chatram line SV Chatram (TANTRANSCO) end:

As per FIR, the line was kept holding from SV Chatram end. Sriperambudur (PGCIL-SR2) end: As per FIR/DR/EL/TR, the line tripped in 3-ph at 00:11:23.726 hrs due to operation of O/C protection. PGCIL (SR-II):

The A/R functionality was implemented through a separate A/R relay at Sriperambudur end. In the instant case, due to problem in Main-CB auxiliary switch, the trigger from A/R relay did not reach all three poles, and resulted in unintended operation/ opening of the Main-CB.

Remedial action: The matter was referred to OEM for permanent solution. As a temporary measure, the unutilized spare

contacts of the Main-CB auxiliary switch had been put to use.

Regarding O/C operation at Sriperambudur end on 400 kV Sriperambudur – SV Chatram line, it was informed that O/C protection was kept enabled when the line was tested last time, However, as it was not disabled inadvertently even after completion of the same, it became manifest during the current incident.

Remedial action: O/C protection at Sriperambudur end on 400 kV Sriperambudur – SV Chatram line was disabled.

Recommendations:

PGCIL (SR-II) to check and revise Pole Discrepancy Relay (PDR) time setting appropriately based on the type of A/R scheme being implemented at their 400 kV Sriperambudur SS.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 11/37

4 Tripping of 400 kV Raichur TPS-Mahboobnagar line

05-04-2016 at 10:23 hrs

Line tripped on operation of Backup impedance protection of line reactor. Direct trip was received at Mahboobnagar end.

GI-2

Raichur TPS (KPCL) end: As per FIR, the line tripped at 10:23:42 hrs due to operation of Backup impedance protection of line reactor.

From DR/EL, A/R lock-out event was observed at 10:23:42.774 hrs. However, no events relating to operation of back-up impedance protection of Line reactor were observed.

Mahboobnagar (TSTRANSCO) end:

As per FIR, the line tripped at 10:24 hrs due to DT receipt from RTPS end. DR/ EL/TR not furnished. SRPC/ SRLDC:

Back-up impedance protection of Line Reactor at RTPS end on 400 kV Raichur TPS - Mehboobnagr line was not in order as there was no signature of any fault in the PMU plot around the occurrence of this tripping.

To this, KPCL stated that it was a typical case of mal-operation of the corresponding electro-mechanical relay, and informed that they were ready to take LR out of service, if permitted, in view of the short length of the line. On this SRLDC stated that even though it was a short line, due to prevailing of high voltages at RTPS, best option would be to convert this LR into a Bus Reactor. However, it was noted that there was neither the availability of additional circuit breaker nor the space required for reconfiguring the bays. As such, KPCL was asked to keep the functioning of concerned electro-mechanical back-up impedance protection relay under observation, and replace it with a spare at the earliest.

When enquired about non-furnishing of Mehboobnagar end’s DR & EL, TSTRANSCO replied that due to wiring problems, they were facing communication problem in downloading DR & EL’s from the corresponding relays, and assured that the same would be set right soon.

Recommendations:

KPCL to keep the functioning of the concerned electro-mechanical back-up impedance protection relay under observation, and replace it with a spare at the earliest.

5

Tripping of 400 kV Hassan-UPCL line-2

07-04-2016 at 12:55 hrs and 13:32hrs

On both the occasions, B-phase to earth fault had occurred in line. At Hassan end breakers tripped in Zone-2 time, i.e., after 350 ms, instead of tripping instantaneously on Carrier aided tripping.

GI-2

Tripping at 12:55 hrs: Hassan (PGCIL-SR2) end:

As per FIR/DR/EL/TR, line tripped at 12:55.46.240 hrs on B-E fault due to DPR, Z2 operation. From DR, it can be observed that carrier signal was received in main-1 which did not pick up during the fault. At

Hassan end breaker tripped after Zone-2 timing due to non receipt of carrier signal in main-2. UPCL end:

As per FIR/DR/EL/TR, line tripped at 12:57.07.407 hrs on B-E fault due to DPR, Z1 operation, and tried to auto-reclose after 1 sec; but tripped in 3-ph due to persistent fault.

Remedial action: UPCL informed that modifications had been carried out for PLCC circuit so as to send carrier signal from relay

directly without involving Contact Multiplier. The modified scheme was tested end to end for both lines on 21-05-16.

KPTCL informed that during the tripping, B-phase to earth fault had occurred in line. Fault was sensed in Zone-2 at Hassan end and in Zone-1 at UPCL end. Protection at UPCL end tried for Auto-reclose but tripped due to persistent fault. As observed from Hassan end DR, carrier signal was received in main-1 which did not pick up during the fault. At Hassan end breaker tripped after Zone-2 timing due to non receipt of carrier signal in main-2. Fault attended: A tree which was in the corridor of the line was removed.

Tripping at 13:32 hrs: Hassan (PGCIL-SR2) end:

As per FIR/DR/EL/TR, line tripped at 13:32:17.790 hrs on B-E fault due to DPR, Z2 operation. From DR, it can be observed that carrier signal was received in main-1 which did not pick up during the fault. At

Hassan end breaker tripped after Zone-2 timing due to non receipt of carrier signal in main-2.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 12/37

UPCL end:

As per FIR/DR/EL/TR, line tripped at 13:33:39.848 hrs on B-E fault due to A/R (Z1) operation, and tried to auto-reclose after 1 sec; but tripped in 3-ph due to persistent fault.

Remedial action: UPCL informed that modifications had been carried out for PLCC circuit so as to send carrier signal from relay

directly without involving contact Multiplier. The modified scheme was tested for both lines on 21-05-16 end to end.

KPTCL informed that during the tripping, B-phase to earth fault had occurred in line. Fault was sensed in zone-2 at Hassan end and in zone-1 at UPCL end. Protection at UPCL end tried for Auto-reclose but tripped due to persistent fault. As observed from Hassan end DR, carrier signal was received in main-1 which did not pick up during the fault. At Hassan end breaker tripped after Zone-2 timing due to non receipt of carrier signal in main-2. Fault attended: A tree which was in the corridor of the line was removed.

Time-sync of DR & EL’s at UPCL needed to be ensured. SRPC/SRLDC:

Even though the tripping at Hassan end in Zone-2 was in order, and was as per the implemented PLCC carrier scheme, it shall be tried on experimental basis for this line exclusively that a Contact Multiplier be used at each end, which upon receiving the carrier signal from the other end on any of the PLCC channels, would replicate it and send to both Main-I and Main-II relays.

PGCIL (SR-II) and UPCL are requested to try the above scheme for 400 kV UPCL – Hassan line, and inform its efficacy to PCSC forum in their next (55th) meeting.

Further, as the width of the carrier signal received at Hassan end has been observed to be very narrow, UPCL is requested use appropriate pulse-stretcher circuit/device at their end so as to generate carrier pulses of adequate width, say 50 - 100 msec.

6

Tripping at 230 kV Ingur substation

08-04-2016 at 15:36 hrs

110 kV “Y“ and “B” phase of BUS-1 PT got failed at Ingur substation. Due to absence of Bus bar protection in 110kV Bus, 230/110kV ICT- 1,2, & 3 tripped on operation of Back up over current protection and all 110 kV tie feeders tripped from remote ends on Z2 operation

GI-1

SLD:

The Single Line Diagram of 230 kV Ingur SS as provided by TANTRANSCO is attached at the end.

As per FIR/TR, 110 KV “Y “ and “B” phase of BUS-1 PT got burst. However, as there was no bus bar protection for 110 kV Bus-1, Auto Transformers - 1, 2, & 3 HV and LV tripped on operation of O/C (IDMT) protection. All 110 kV tie-feeders tripped at their respective remote ends on DPR, Z2 operation. Additionally for Auto Transformer – 3, % bias & high-set differential protection also acted due to bypassing of its LV side R &Y phase live tank CTs by the arcing spread from the adjacent failed PTs.

Remedial action: Bus-II at Ingur charged at 16.10hrs on 08.4.2016. For 110 kV Tiruvachi feeder and 110kV Thingalur feeder normal supply availed from Ingur Bus-I. After

conducting TAN DELTA test and RATIO test on LV3 CTs, Auto-transformer 3 was energized at 12.50 hrs on 09.04.2016.

3 nos. of new 110 kV Vidyuth-make PTs were commissioned in Bus-I after carrying out the pre-commissioning tests on 10.04.2016.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 13/37

As per TANTRANSCO’s Report dated 25.04.2016:

7

Tripping of 400kV Gajuwaka-Simhadri line-2 and 400kV Gazuwaka-Vijayawada line

10-04-2016 at 4:21 hrs

400kV Gajuwaka-Simhadri line-2 tripped on an R-phase to earth fault. Line tripped in zone-2 at Simhadiri end. 400kV Gazuwaka-Vijayawada line also got tripped during the incident at Gazuwaka end only.

GI-2

At 400 kV Gajuwaka SS, Simhadri Line-2 (Main-CB: 13) – (Tie-CB: 14) – (Main-CB: 15) Vijayawada Line are in same diameter.

400 kV Gajuwaka – Simhadri line-2 Gajuwaka (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped (in R-ph) at 04:21:01.433 hrs on R-E fault due to DPR, Z1 operation. Main-CB (13) & Tie-CB (14) R-ph poles got opened;

As DR’s time-scale was restricted to 800 msec, the following further observations could be made from EL:

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 14/37

During A/R’s dead-time at around 04:21:01.530 hrs Gajuwaka – Vijayawada line got tripped from Gajuwaka end opening its respective Main and Tie CB’s (M-CB: 15; T-CB: 14).

It was further observed that Tie-CB (14) and Main-CB (15)’s Trip Circuits were found to be faulty around 04:21: 01.950 hrs.

It was also observed that at 04:21:03.867 hrs, the other poles (Y & B) of Main-CB (13) got opened due to PDR operation. ----------------- Reasons for this?

From above observations of EL, it can be deduced that line failed to auto-reclose at Gajuwaka end. Simhadri (NTPC) end:

As per FIR/DR/EL/TR, the line tripped at 04:21:01.773 hrs on R-E fault due to DPR, Z2 operation. 400 kV Gajuwaka – Vijayawada S/C line Gajuwaka (PGCIL-SR1) end:

As per FIR/TR, the line tripped at 04:21 hrs on R-N and Y-N faults due to DPR operation. It was stated that 01 No. tension insulator was decapped at Loc No. 845.

From EL, it was observed that the line had tripped at around 04:21:01.530 hrs opening its respective Main and Tie CB’s (M-CB: 15; T-CB: 14).

Vijayawada (PGCIL-SR1) end:

As per FIR, the line was kept holding from Vijayawada end.

As per EL, the line tripped at 05:12:17.720 hrs on R-N and Y-N faults due to DPR operation. It was also observed that respective Main-CB (24) and Tie-CB (23) went into LOCK-OUT.

DR furnished (triggering time = 04:21:01.397 hrs) did not show the above events. Time-sync between DR and EL needs to be ensured.

PGCIL (SR-II) representative informed that the line was hand-tripped from Vijayawada end. PGCIL (SR-I):

The observed anomalies at Gajuwaka SS were because of the Insulator tracking phenomenon that severely affected their SS in April, 2016. Due to dense fog in and around Vizag Substation mixed with saline pollutants caused visible/audible tracking in the insulators and resulted in insulation breakdown and decapping of insulators.

Remedial action: Cold line washing of entire HVAC, HVDC Pole-1 & 2 including Filter Banks had been carried out. In Gajuwaka SS, all Strung Bus Porcelain insulators had been replaced with CLR Polymer type insulators. RTV Silicon High Voltage Insulation Coating on BPI insulator stacks and Isolator support structures connected

to 400kV Bus had been completed. In 400kV Simhadri – Gajuwaka – 1 & 2 Lines, all the porcelain insulators had been replaced with CLR Polymer

insulators. In 400kV Vijayawada – Gajuwaka S/C line, transmission lines porcelain insulators up to 30 km radius had been

replaced with CLR Polymer insulators. In 400kV Jeypore – Gajuwaka – 1 & 2, it was proposed to replace porcelain insulators with CLR Polymer

insulators up to 30 km radius. The work is under progress. In 400kV Simhadri – Vemagiri – 1 & 2, it was proposed to replace porcelain insulators with CLR Polymer

insulators up to 30 km radius. PLCC end-to-end testing on Gajuwaka – Simhadri line-2 was carried out on 28.04.2016, and ensured that PLCC

carrier communication is in healthy condition.

8

Tripping of 400kV Coastal-Tuticorin PS line and Unit-1 at NTPL

11-04-2016 at 7:05 hrs

Line tripped on a B-phase to earth fault and auto-reclose attempt was unsuccessful due to persistent fault. Running Unit-1 at NTPL got tripped during the incident.

GI-2

Tripping of 400 kV CEPL-TTNPS line: CEPL end:

As per FIR/DR/EL/TR, line tripped at 07:04:43.517 hrs on B-E fault due to DPR, Z1 operation, and tried to auto-reclose after 1.2 sec; but tripped in three-phase due to persistent fault.

From EL, it can also be observed that GCB (of CEPL Unit-1) had tripped at 07:04:45.100 hrs (which is as per the SPS in place at CEPL)

TTNPS (PGCIL-SR2) end:

As per FIR/DR/EL/TR, line tripped at 07:04:43.510 hrs on B-E fault due to DPR, Z2 (CAT) operation, and tried to

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 15/37

auto-reclose after 1 sec; but tripped in three-phase due to persistent fault. Tripping of NTPL Unit-1:

As per FIR/DR/TR, Unit-1 tripped at 07:05:03.230 hrs due to operation of Low Forward Power protection. In EL, the events relating to Unit-1 tripping at 07:05 hrs were not captured. However, it can be noticed that

Unit-1 trip occurred at 06:58:03.320 hrs due to Low Forward Power protection.

Time-sync of DR & EL of Unit-1 relays needed to be ensured. NTPL:

Unit-1 tripped not due to low forward power protection, but due to operation of its prime-mover Motor’s protection on high steam temperature, and informed that appropriate remedial action had been taken at their end.

In this regard, it was enquired whether NTPL had properly kept the fault ride through time delay in VFD Speed Sensor relay for the generating units, and requested to ensure that it is kept appropriately (typically 2 sec) to avoid unwarranted Unit trippings on account of transient voltage dips in auxiliary bus voltage.

9 Tripping of 400kV Raichur TPS Bus-2

13-04-2016 at 21:12 hrs

Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed. Unit-4 got tripped on operation of Generator Differential, Reverse power & LBB protection. Operation of LBB protection led to tripping of BUS-2 at RTPS

GI-2

SLD:

The single line diagram of 400/ 220 kV Raichur TPS as provided by KPCL is attached at the end.

As per FIR, 400 kV Bus-2 got tripped at 21:12:02 hrs due to operation of LBB protection. It was stated that during the synchronization process of Unit-4, when the excitation voltage was at 15 kV, the Y-Pole of Tie-breaker (of Unit-4) got blasted. As a result, Unit-4 tripped on Generator Differential, Reverse power & LBB protection. Operation of LBB protection led to tripping of 400 kV BUS-2 at RTPS.

The uploaded DR & EL & TR could not be downloaded. KPCL:

KPCL informed that Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed while synchronising it. Unit-4 got tripped on operation of Generator Differential, Reverse power & LBB protection protections. It was explained that due to surface conduction over the Unit-4 Tie-breaker, LBB relay of 400 kV Bus-2 got operated leading to tripping of all breakers connected to it. The reason for surface current was attributed to the deposition of ash, heavy mist & humidity on account of Unit-4’s proximity to cooling towers.

In this regard, SRPC/ SRLDC brought to KPCL’s attention the occurrence of similar event due to LBB operation of Main & Tie breakers of Unit-7 on 12.11.2015 at 00:30 hrs (discussed in 49th meeting of PCSC held on 30.11.2016), when it was recommended among other things to provide dedicated breaker flashover protection, and to take necessary preventive measures such as measurement of dynamic contact resistance, and over-hauling (hot-line washing) of breakers at regular intervals to ensure healthiness of breakers.

To this, KPCL informed that hot-line washing of breakers is already in place. Further, they have also initiated steps (tendering is in progress) for applying RTV Silicone high voltage insulator coatings to all ceramic insulators of

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 16/37

equipment like CT, PT, CB, Isolators etc.

When enquired about providing breaker flashover protection, KPCL assured that they would look into it. To this, it was explained that breaker flashover is an abnormal condition and may result in severe damage to capital equipment like Generator and Generator Transformer. Additionally it may also result in explosion of Circuit Breakers which can damage the nearby equipment in Switchyard and put Substation personnel at risk. As such, detection of flashover reliably and operating the protection system to isolate the affected breaker and generator in minimum possible time is all the more important, and informed that such a protection can be implemented using a logic based on immediate sensing of arc current supported by breaker status to reliably declare a flash. In this regard, papers contributed by Sh. Sanjay Bhatt, UPCL on “Adaptive Logic for Breaker Flashover Protection” is enclosed at Reference-I for kind perusal and necessary action.

Recommendations:

KPCL to keep to undertake the following remedial measures to avoid breaker flashovers: replacing all porcelain insulators with composite insulators carrying out hot-line water washing of all insulators on regular basis. applying Room Temperature Vulcanizing (RTV) Silicone high voltage insulator coatings to all bus-connected

ceramic insulators of equipment like CT, PT, CB, Isolators etc. KPCL to take steps to provide dedicated breaker flashover protection to all breakers at Raichur TPS at the earliest.

10 Tripping of HVDC Gazuwaka Pole-1

14-04-2016 at 18:33 hrs

IDMT E/F & subsequent operation of BFR protection of CWC-33 filter of south side of Pole-1 caused opening of Pole-1 connected south filter CB and Pole-1 went into standby mode due to non-availability of South filter.

As per FIR/TR of Gajuwaka SS of PGCIL (SR-I):

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 17/37

11 Tripping of HVDC Talcher-Kolar Pole-1 & Pole-2

Pole-1 at 18:42 Hrs on 14-04-2016

HVDC Talcher-Kolar Pole-1 tripped at Talcher end due to tripping of valve cooling system of Pole-1 as fire has occurred in Valve Cooling UPS System.

Pole-2 at 19:44 Hrs on 14-04-2016

Pole-2 tripped on due to suspected mal-operation of SF6 Gas Pressure Monitor of star-bushing of Y-phase transformer

Tripping of HVDC Talcher-Kolar Pole-1 at Talcher end at 18:42 hrs:

As per TR of Kolar HVDC Terminal of PGCIL (SR-II):

Tripping of HVDC Talcher-Kolar Pole-2 tripped at Talcher end at 19:44 hrs:

As per TR of Kolar HVDC Terminal of PGCIL (SR-II):

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 18/37

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 19/37

When enquired about the low load relief obtained from Tamil Nadu substations, TANTRANSCO replied that they would look into it and furnish appropriate details with reasons. Subsequently, TANTRANSCO vide their letter dated 28.05.2016 informed the following:

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 20/37

12 Tripping of Gajuwaka HVDC Poles - 1&2

15-04-2016 at 12:23 hrs

Poles tripped due to loss of East bus voltage due to disturbance in Eastern region.

As per TR of HVDC Gajuwaka SS of PGCIL (SR-I):

13

Tripping of Units at Raichur TPS

15-04-2016 at 15:36 hrs

During testing of retrofitted distance protection in 400kV Raichur-2 feeder, LBB protection trip DC got extended to Bus trip. This resulted in tripping of 220kV bus at RTPS and all connected 220 kV elements. Unit-4 which is connected to 400 kV Bus got tripped due to tripping of Station Utility Transformer that is connected 220 kV bus

GI-2

Unit-2 tripping:

As per FIR/EL, Unit-2 tripped at 16:49:38.850 hrs due to BBP lock-out relay operation & 86 GB (CLASS-C) trip. It was stated that DR was not available Time-sync at 220 kV RTPS needed to be ensured. Unit-3 tripping:

As per FIR/EL, Unit-2 tripped at 15:46:32.890 hrs due to operation of 220 kV LBB/ BBP protection& 86 GB (CLASS-C) trip.

It was stated that DR was not available Time-sync at 220 kV RTPS needed to be ensured. Unit-4 tripping:

As per FIR, Unit-4 in RTPS was running at 100MW load (Replaced GT-4 was under observation) with its auxiliaries on Station Transformer. On 15-04-2016 at 15.50 hrs. Bus Bar Protection was operated in RTPS 220kV station resulting in tripping of Station Transformer. The tripping of Station Transformer caused tripping of Unit-4.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 21/37

As per TR of KPCL:

KPCL informed that at the time of the incident, Unit Auxiliary Transformer of Unit-4 was under maintenance; hence Unit-4’s auxiliaries were being fed from the Station Transformer-4 (ST-4). As ST-4 was deriving its power from 220 kV bus, and since 220 kV side was being operated on single-bus, LBB operation of 220 kV Bus led to tripping of ST-4. This failure of supply to Unit-4 auxiliaries resulted in tripping of Unit-4.

It was noted from above that Unit-4 tripping was basically due to single-bus operation on 220 kV side.

It was also noted that trippings involving KPCL’s major generating stations such as 400/ 220 kV Raichur TPS and 220 kV Nagjheri TPS were found to be occurring with definite pattern. Hence, to discuss all outstanding protection issues of KPCL, it was considered prudent to convene a special meeting with higher management of M/s KPCL so that appropriate action could be initiated in right time.

Recommendations:

In view of the availability of two buses along with healthy bus-coupler at 220 kV RTPS, KPCL is recommended to put in service the double-bus operation at 220 kV RTPS by suitably distributing loads within 15 days.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 22/37

14 Tripping of HVDC Gajuwaka Pole- 1

16-04-2016 at 10:18 hrs

East Converter Transformer Y-phase OLTC Tap gone out of step as compared to R and Y-Phases

As per TR of HVDC Gajuwaka Terminal of PGCIL (SR-I):

15 Tripping of ICT-2 at Cudappah station

20-04-2016 at 21:14 hrs

ICT tripped on operation of Bus Reactor TEED protection

GI-2

At Kadapa SS of PGCIL (SR-I), ICT-2 and Bus Reactor are in same dia. Bus Reactor’s CB’s are: Main-CB = 13; Tie-CB = 14.

As per FIR, ICT-2 tripped at 21:14 hrs due to operation of Bus Reactor TEED protection. As per EL, Bus Reactor tripped at 21:15.00.205 hrs due to operation of its Biased Differential Protection.

(Nothing was said about ICT-2 tripping)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 23/37

As per DR, Bus Reactor tripped at 21:15.11.650 hrs due to operation of 3-ph Group-B protection (heavy fault current was observed in B-ph).

The furnished DR & EL showed events relating to Bus Reactor only, and that relating to ICT-2 tripping had not been furnished.

PGCIL (SR-I):

At Kadapa SS, ICT-2 and Bus Reactor (BR) were in same dia. At the time of tripping, BR was under shutdown, and a scaffold erected in the adjacent bay (to undertake some maintenance activites) accidentally fell upon the conductor portion between the BR breaker and its line-side (away from BR) isolator. This created a fault in the differential zone of the BR. As a significant amount of this fault current (> 10 kA) was contributed by ICT-2, it also tripped on high-set operation of the corresponding O/C protection.

16 Tripping of 400kV Sattenapalli-Srisailam line-2

21-04-2016 at 1:40 hrs

Line tripped on Direct Trip receipt at Sattenapalli end

GI-2

21-04-2016 at 13:40 hrs

R-Ph to earth fault had occurred in line. Direct Trip receipt was observed in DR of Sattenapalli and Srisailam.

GI-2

Tripping at 01:40 hrs: Sattenapalli (APTRANSCO) end:

As per FIR/DR/EL, line tripped at 01:40:37.731 hrs due to DT receipt from Srisailam end. Srisailam (TSGENCO) end:

As per FIR, line tripped at 01:37 hrs due to OVR operation. As per TR, line tripped at 01:35.33.135 hrs due to OVR, Stage-I operation. From DR/EL, line tripped at 01:38:01.463 hrs. However, its cause could not be established from them as the

status of line voltages prior to CB opening were not recorded in either DR or EL.

Reasons for line tripping at Srisailam end were not clear as events prior to CB opening were not shown. Time sync of DR & EL with GPS at Sattenapalli and Srisailam needed to be ensured. TSGENCO: The DR & EL submitted were that if Main-I relay whereas trip due to OVR operation came from Main-II relay.

To this, SRPC/ SRLDC stated that for any tripping, only relevant DR’s & EL’s corresponding to the tripping under consideration only should be made available/ uploaded in SRLDC web-portal, and requested TSGENCO to furnish appropriate DR & EL to substantiate above tripping was due to OVR operation at Srisailam end.

Tripping at 13:40 hrs: Sattenapalli (APTRANSCO) end: As per FIR/DR/EL, line tripped at 13:31:19.018 hrs due to DT receipt from Srisailam end. Srisailam (TSGENCO) end:

As per FIR/DR, line tripped at 13:28:42.421 hrs on R-E fault due to DPR, Z1 operation. As per EL, line tripped at 13:26:14.505 hrs on R-E fault due to DPR, Z1 operation. Time sync of DR & EL with GPS at Sattenapalli and Srisailam needed to be ensured. SRPC:

In the past also, there were several instances of Srisailam bound lines tripping at remote end substations of APTRANSCO due to DT receipt from Srisailam end on account of occurrence of faults on those respective lines.

The issue was discussed in earlier PCSC meetings also, when TSGENCO informed in the 49th meeting of PCSC held on 30.11.2015 that the newly commissioned numerical relays had some configuration problems due to which DT was being sent to remote ends wrongly. TSGENCO also informed in the said meeting that the matter had been taken up with the concerned OEM, and hoped to resolve the issue at the earliest.

However, the fact that similar events were found to be occurring even after six months implied that no definite action had been taken by TSGENCO to resolve the issue. To this, TSGENCO assured that they would soon address the issue.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 24/37

In this context, APTRANSCO requested to allow them to disable A/R at Kurnool and Sattenapalli ends on 400 kV Srisailam bound lines, since the same was not in place at Srisailam end.

On this, it was noted that the lines emanating from 400 kV Srisailam Generating Station were composite lines (combination of cable & over-head transmission lines). Taking note of the reservations expressed by TSGENCO in implementing A/R at Srisailam end, PCSC forum agreed to temporarily disable A/R at Kurnool & Sattenapalli ends on 400 kV Srisailam bound lines, until a clear-cut decision is taken in implementing A/R on composite lines such as those emanating from 400 Srisailam LB.

Recommendations:

TSGENCO to resolve configuration problems associated with the newly commissioned relays at 400 kV Srisailam LB latest by 30.06.2016 so that unwarranted DT sending to remote end substations of APTRANSCO is addressed.

17

Tripping of HVDC Gazuwaka Pole-1&2 and tripping of 400kV Jeypore-Gazuwaka line-1&2

22-04-2016 at 18:16 hrs

400kV Jeypore-Gazuwaka line-1&2 and HVDC Gazuwaka pole-1&2 got tripped during the incident. As per FIR, HVDC pole-2 got blocked due to loss east voltage from pole-1 east bus. HVDC pole-1 got blocked due to loss of all filters of east side. 400kV Jeypore-Gazuwaka line-1 tripped on direc trip receive and 400kV Jeypore-Gazuwaka line-2 tripped on Z-4.

GI-2

Tripping of 400 kV Gajuwaka – Jeypore Line-1: Gajuwaka (PGCIL-SR-1) end:

As per DR/TR, the line tripped at 18:16:40.894 hrs (as per EL, this event occurred at 18:16:41.890 hrs) due to DT

receipt from Jeypore end. But due to tracking in inulators, current flow was observed in all the three poles, due to

which LBB operation took place at 18:16:41.150 hrs. The following additional observations could be made from

DR:

Distance protection Zone-4 operation was observed for about 200 msec starting from 18:16:40:950 hrs at

Gazuwaka. (Is this trip or pick-up?)

Current was observed in R-phase even after opening of breakers at Gazuwaka.

LBB protection got operated at Gazuwaka at 18:16:41.150 hrs. However, Direct Trip sent was not observed

in the digital channel. At this instant, Distance protection operation (in Z1, Z2, Z3) was observed.

In TR, it was mentioned that from 18:04 hrs onwards, severe voltage fluctuations from 280 kV to 440 kV on East

Bus were observed. It was also stated that tripping of some of the 400 kV lines in the eastern region could have

caused voltage fluctuations.

Tripping of 400 kV Gajuwaka – Jeypore Line-2: Gajuwaka (PGCIL-SR-1) end:

As per DR, the line tripped in 3-ph at 18:16:41.470 hrs apparently due to Over Voltage conditions. But due to

tracking in insulators, current flow was observed in all the three poles, due to which LBB operation took place at

18:16:41.680 hrs (as per EL, LBB operation event occurred at 18:16:42.450 hrs). The following additional

observations could be made from DR:

Z4 operation observed twice for about 200 msec each time starting from 18:16:40.970 hrs and 18:16:41.500

hrs respectively. (Is this due to Insulator tracking?)

There is absence of R-phase voltage for about 200 msec starting from 18:16:40.970 hrs. R-phase voltage re-

appears after 200ms.

Main-CB tripped at 18:16:41.500 hrs, i.e., after 500ms on Z4 operation. (But Z4 operation sustained for

about 200 msec)

Tie-CB tripped at 18:16:41.700 hrs due operation of LBB protection.

It was stated in TR that BFR operation was due to pollution around Vizag Substation mixed with saline pollutants

causing visible/audible tracking in the insulators and thereby causing insulation breakdown and external

conduction.

Time-sync difference of 1 sec between DR and EL needed to be set right

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 25/37

Tripping of Gajuwaka HVDC Pole-1: As per TR, from 18:04 hrs onwards, severe Voltage Fluctuations on East Bus were observed from 280kV to 440kV.

Voltage fluctuations along with Voltage Imbalance caused tripping of all East Side filters of Pole-1 on System

conditions, there by Blocking the Pole-1 due to loss of all filters of East Side.

Tripping of Gajuwaka HVDC Pole-2: As per TR, from 18:04 hrs onwards, severe Voltage Fluctuations on East Bus were observed from 280kV to 440kV.

However, Pole-2 got Blocked due to loss of East Side Voltage from Pole-l East Bus.

PGCIL (SR-I): The observed anomalies at Gajuwaka SS were because of the Insulator tracking phenomenon that severely

affected their SS in April, 2016. Due to dense fog in and around Vizag Substation mixed with saline pollutants caused visible/audible tracking in the insulators and resulted in insulation breakdown and decapping of insulators.

In the instant case, the tripping of Jeypore-Gajuwaka line-2 at Gajuwaka end was due to LBB operation of CWD20Q52 caused by tracking across the grading capacitors connected across the breaker. This resulted in opening of all breakers connected to East Bus-II including CWD10Q52. However, near subsequent LBB operation of CWD10Q52 (caused again due to insulator tracking) led to opening of CWD10Q50. This opening of both Main-CB (CWD10Q52) and Tie-CB (CWD10Q50) effectively resulted in tripping of the line.

Remedial action: Cold line washing of entire HVAC, HVDC Pole-1 & 2 including Filter Banks had been carried out. In Gajuwaka SS, all Strung Bus Porcelain insulators had been replaced with CLR Polymer type insulators. RTV Silicon High Voltage Insulation Coating on BPI insulator stacks and Isolator support structures connected

to 400kV Bus had been completed. In 400kV Simhadri – Gajuwaka – 1 & 2 Lines, all the porcelain insulators had been replaced with CLR Polymer

insulators. In 400kV Vijayawada – Gajuwaka S/C line, transmission lines porcelain insulators up to 30 km radius had been

replaced with CLR Polymer insulators. In 400kV Jeypore – Gajuwaka – 1 & 2, it was proposed to replace porcelain insulators with CLR Polymer

insulators up to 30 km radius. The work is under progress. In 400kV Simhadri – Vemagiri – 1 & 2, it was proposed to replace porcelain insulators with CLR Polymer

insulators up to 30 km radius. PLCC end-to-end testing on Gajuwaka – Simhadri line-2 was carried out on 28.04.2016, and ensured that PLCC

carrier communication is in healthy condition.

18

Tripping of HVDC Gazuwaka Pole-1&2

Pole-1 at 20:44 hrs & pole-2 at 21:01 hrs on 22-04-2016

Pole-1 blocked due to operation of BFR of south side filter CWC-36. Pole-2 tripped on loss of East side voltage from HVDC pole-1due to tripping of East bus-1 extension on differential trip.

GI-2

Tripping of Gajuwaka HVDC Pole-1: Gajuwaka (PGCIL-SR-1) end:

As per TR, POLE-1 was Blocked due to operation of BFR of 01 no. of South Side In-Service Filter, i.e., CWC36

which tripped on "IDMT ElF protection". Later, it was investigated that the very severe Corona discharge being

observed in the switchyard equipments in the form of tracking caused flashovers and subsequent operation of E/F

protection of respective elements.

Filter Breaker BFR protection was due to external conduction across the Grading capacitor thereby tripping the

Main and Tie Breaker of Filter Bus and Blocking the Pole-1. Similar type of tracking was also observed inside the

filter banks and resulted in tripping of Filter on "IDMT E/F protection"

Tripping of Gajuwaka HVDC Pole-2: Gajuwaka (PGCIL-SR-1) end:

As per TR, Pole-2 was blocked on loss of East Side Voltage from HVDC Pole-l due to tripping of East Bus-1

Extension on "Differential Current Phase L1 trip".

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 26/37

19 Tripping of 400 kV Madurai-Udumalpet line

23-04-2016 at 10:57 hrs

Line tripped during disturbance at 230kV Myavdi TNEB SS as Main-I relay picked up in zone- 3

GI-2

400 kV Madurai – Udumalpet S/C line: Udumalpet (PGCIL-SR2) end:

As per FIR, the line was kept holding Madurai (PGCIL-SR2) end:

As per FIR/EL/TR, the line tripped (in 3-ph) at 10:57:03.045 hrs on R-Y fault due to DPR, Z3 operation. From DR, this event (Z3-trip) seemed to have occurred at 11:57:03.044 hrs. Also Z3-trip happened almost

instantaneously with the occurrence of R-Y fault. However, CB’s (152 & 252) were observed to be in CLOSED condition.

Time sync of DR & EL at 400 kV Madurai SS of PCIL (SR-II) needed to be ensured. PGCIL (SR-II):

The instantaneous Z3 trip was given by the newly commissioned Main-II (Micom P44) relay. Upon investigation with the help of OEM, they found that due to some additional/ wrong PSL logics, the relay was configured to give instantaneous trip in case of L-L faults.

Remedial action: The wrong/ additional PSL logics responsible for instantaneous trip in case of L-L faults had been removed.

On this, KSEB remarked that commissioning engineers should be properly instructed to disable all old settings while configuring relays with new settings.

KPTCL mentioned that not only during commissioning, even while undertaking testing activities also due care should be taken to disable/ enable requisite/ appropriate protections.

20

Tripping of 400 kV Ramagundam – Chandrapur lines 1 & 2 and HVDC Poles 1 & 2.

Line-1 on 04-05-2016 at 19:16 hrs & Line-2 on 04-05-2016 at 19:26 hrs

Line-1 tripped at 19:16:01 hrs on B-E fault, but auto-reclosed only at Chandrapur end. Line-2 tripped at both ends on B-E fault at 19:26 hrs. HVDC Poles – 1 & 2 were tripped at 19:26 hrs due to AC under-voltage on South-Bus.

GI-2

400 kV NTPC-Ramagundam – Chandrapur Line-1: Ramagundam (NTPC) end:

As per FIR/DR/EL/TR, line tripped (in B-ph) at 19:16.02.673 hrs on B-E fault due to A/R operation.

As DR’s scale was restricted to 280 msec, the following observations were made from EL: Within 350 msec from the instant of A/R initiation, the R & Y poles of Tie-CB got opened due to AUTO-TRIP

and it’s A/R went into LOCK-OUT. Finally, the R & Y poles of Main-CB got opened at 19:16:04.544 hrs due to PDR operation.

Chandrapur (PGCIL-WR1) end:

As per DR/EL/TR, line tripped at 19:16:02.688 hrs on B-E fault due to A/R operation, and successfully auto-reclosed after 1 sec.

It was mentioned in TR that the line tripped again at 19:16:10.900 hrs due to DT receipt from Ramagundam end. However, no DR and EL were furnished for this event.

400 kV NTPC-Ramagundam – Chandrapur Line-2: Ramagundam (NTPC) end: As per FIR/DR/EL/TR, line tripped (in B-ph) at 19:26.56.312 hrs on B-E fault due to DPR operation, and tried to

auto-reclose at 19:26:57.446 hrs; but tripped in 3-ph due to persistent fault. Chandrapur (PGCIL-WR1) end: As per TR, line tripped (in 3-ph) at 19:26 hrs on B-E fault due to DPR, Z1 operation. A/R was in BLOCKED condition

as 400 kV Ramagundam – Chandrapur line-1 was not in service. Tripping of HVDC Poles - 1 & 2: As per FIR/ TR of PGCIL (WR-I), the following could be noted: On 04/05/2016 at 19:16Hrs, Bhadrawati - Ramagundam # 1 line tripped on DT receive from Ramagundam end

and Pole-1 & 2 were carrying 700 MW,W-->S direction with Bhadrawati - Ramagundam # 2 in service . At 19:26hrs, Bhadrwati - Ramagundam # 2 line tripped on B-Phase to Earth fault. Subsequently, due to AC under-voltage on South Bus, both the Poles tripped on "GROUND FAULT" & "DC>AC" alarms.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 27/37

At 20:21Hrs, Ramagundam line-1 was charged thereby energising South Busbar. Then an attempt was made to deblock Pole-2 but the pole failed to deblock due to “RPC request to standby” signal from Reactive power Control(RPC). From the MPM alarms, it was found that the availability of the filters in both West & South side was not being updated by RPC-A & RPC-B and hence the RPC did not allow to energise the poles.

During investigation, the RPC, pole control & protections and PLC panels were checked for status signals of filters, pending alarms/card failures if any. The control and protection panels were found healthy.

Meanwhile, on 05.05.2016 at 01:59Hrs, Ramagundam-1 line tripped at on Over voltage protection operated at Bhadrawati end. Line was taken back into service at 02:59Hrs.

The filter availability was made available to RPC by resetting the power supply units and processor cards in RPC and both the Poles were normalised on 05/05/2016 at 04:40Hrs & 03:40Hrs respectively.

SRLDC:

ED, SRLDC stated that A/R failure at RSTPS end for the fault on line-1, and then auto-reclosure attempt from NTPC-Ramagundam for a subsequent fault on line-2, implied that (i) A/R was unhealthy, and (ii) the agreed A/R logic for 400 kV RSTPS – Chandrapur D/C line was not implemented at RSTPS end.

NTPC-Ramagundam:

Auto-Reclosure (A/R) had been recently configured, and was implemented from Main-I relay. As the present tripping was the very first tripping after it was put into service, its healthiness as well as configuration logic would be checked in the next shutdown planned to be availed in June, 2016.

Recommendations:

NTPC-Ramagundam to properly configure A/R functionality at RSTPS end as per the agreed logic for the faults on 400 kV RSTPS – Chandrapur D/C line, and furnish an action taken report to PCSC forum on the correctness of its operation.

III. Failure or non-operation of Auto reclose during transient fault

For all below cases of A/R non-operation, the time scale for the DR should be properly configured, say two sec, post triggering to capture complete A/R operation.

Sl. No.

Element Date & Time Reason

Category

1 Tripping of 400kV NCTPS-Vallur line-2

02-04-2016 at 2:09 hrs

Line tripped on R-phase to earth fault. Line auto-reclosed at NCTPS end and tripped at Vallur end.

GI-2

Vallur (NTECL) end: As per FIR/DR/EL/TR, the following took place. NCTPS Line 2 – R phase tripped on Diff Trip L1 @ 2:08:37:435 hrs 3-ph trip was issued @ 2:08:37:489 hrs. Then, the line tripped @ 2:08:37:520 hrs. During R phase fault @ 2:08:37:435 hrs, the fault currents observed were (R-ph = 21.1 kA; Y-ph = 1.3 kA; B-ph

= 0.1 kA) It was stated that in Main-1 relay, the fault was detected as L1 – L2 fault since there was also a rise in Y ph

current during fault. With single phase differential trip and phase selection of ph – ph, 3 phase trip was initiated.

NCTPS (TANGEDCO) end:

As per FIR/DR/EL/TR, the line tripped at 02:08:37.432 hrs on R-E fault due to operation of Line Differential Protection (LDP), and successfully auto-reclosed after 1 sec. However, A/R closing event was not shown in DR as it’s time scale was restricted to 160 msec.

Remedial action: AR successful at NCTPS-II end. Breaker tripped at Vallur end. Feeder hand tripped at NCTPS-II end at 03:21:52

hrs. Line patrol was done and declared no visible fault. NTECL:

In the instant case, even though Y-ph current was low, 3-ph trip had been given as it was extended from line differential protection on account of detection of L-L fault. As remedial action, now the 3-ph trip was extended from “ZCOM” only. Further, operating settings of ZCOM for L-L faults had also been suitably revised upwards.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 28/37

2 Tripping of 230kV Yerandahalli-Hosur line

03-04-2016 at 12:48 hrs

Line tripped on a R-phase to earth fault. Auto-reclose was successful at Hosur. A/R not available at Yerandahalli.

GI-1

Yerandanahalli (KPTCL) end: As per FIR, the line tripped at 12:21 hrs on R-E fault due to DPR, Z3 operation.

It was stated in FIR that facility to download DR & EL were not available at Yerandanahalli. Hosur (TANTRANSCO) end:

As per FIR/TR, the line tripped at 12:57:12.310 hrs on R-E fault due to DPR, Z1 operation, and successfully auto-reclosed.

But successful A/R operation could not be established from the furnished DR & EL due to constriction in their time-scales.

KPTCL:

At Yerandanahalli: Radially fed from Hosur. But tripped on DPR in Zone-3 during the instance. Reason: Tripping of line at Yeranadanahalli was due to problem in VT fuse fail block & loss of potential during

dead time of AR operation from remote end.

Remedial action: VT fuse fail block had been verified and attended. Auto reclosure feature would be enabled at Yeranadanahalli end after replacement of main-1 protection

(existing is OPTIMHO relay).

3 Tripping of 400 kV Kalvindapattu-Vallur line

10-04-2016 at 14:59 hrs

R-phase to earth fault had occurred in line. Auto reclose attempt is unsuccessful/ auto-reclose could not be established from provided DR/ EL.

GI-2

Vallur (NTECL) end:

As per FIR/DR/EL/TR, the line tripped (R-ph) at 14:59:14.800 hrs on R-E fault due A/R ( Z1) operation. However within 100 msec from the instant of R-ph pole tripping, the other poles, viz., Y-ph & B-ph, also got tripped due to receipt of DT from Kalavindapattu end.

Kalavindapattu (PGCIL-SR2) end:

As per FIR/TR, the line tripped (in R-ph) at 14:59 hrs on R-E fault due A/R operation, but tripped in 3-ph due to unsuccessful A/R operation.

From DR, successful A/R operation could not be established as only the events after A/R closure operation were shown. Further, A/R seemed to have taken place on Y-ph Pole for R-E fault.

In EL, time stamp resolution was limited to SECONDS, instead of msec. Further events pertaining to successful A/R operation were not present. However, DT SEND event to the Vallur end was observed at 14:59.15 hrs

Recommendations:

PGCIL (SR-II) to furnish a report on the tripping event detailing the reasons for unsuccessful A/R operation at Kalvindapattu end, and the remedial action taken to restore A/R to normalcy.

4 Tripping of 400kV Vijayawada-Nellore line-2

11-04-2016 at 6:43 hrs

Line tripped on a B-phase to earth fault. Attempt for Auto-reclose or unsuccessful auto-reclose could not be established from DR and EL furnished.

GI-2

Vijayawada (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped (in B-ph) at 06:15:12.416 hrs on B-E fault due A/R operation, but within 50 msec, the other two poles (R-ph & Y-ph) poles also got opened.

Nellore (PGCIL-SR1) end:

As per FIR/DR/EL/TR, the line tripped (in B-ph) at 06:17:57.330 hrs on B-E fault due A/R operation, but within 55 msec, the other two poles (R-ph & Y-ph) poles also got opened.

In EL, time stamp resolution was limited to SECONDS, instead of msec. Further events pertaining to successful A/R operation were not present. However, DT SEND event to the Vallur end was observed at 14:59.15 hrs

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 29/37

Recommendations: PGCIL (SR-I) to furnish a report on the tripping event detailing the reasons for unsuccessful A/R operation at

Vijayawada and Nellore ends, and the remedial action taken to restore A/R to normalcy.

5 Tripping of 400kV Coastal-NTPL line

18-04-2016 at 4:25 hrs

Line tripped on a Y-phase to earth fault. Line auto-reclosed at Coastal end and did not reclose at NTPL and Y&B pole tripped on pole-discrepancy.

GI-2

CEPL end:

As per FIR/DR/EL/TR, the line tripped (in Y-ph) at 04:25:06.732 hrs on Y-E fault due A/R (Z1) operation, and successfully auto-reclosed after 1 sec.

In DR, continuous Y-ph voltage was observed even during A/R dead-time. NTPL end:

As per FIR/DR/EL/TR, the line tripped (in Y-ph) at 04:25:06.732 hrs on Y-E fault due to A/R (Z1B) operation, but failed to auto-reclose after 1-sec dead-time. It was stated that A/R had failed to operate due to AC Supply failure for Breaker Hydraulic Pump (Y-Phase).

It was observed from EL that finally R-ph & B-ph Poles got opened at 04:25:09.183 hrs due to PDR operation. (This means PSAG-15 recommendation of changing PDR time delay from 2.5 sec to 1.5 sec has not yet been implemented).

In view of above, NTPL is recommended to immediately change PDR timing from 2.5 sec to 1.5 sec for all lines emanating from their switchyard.

Remedial action NTPL informed that AC supply had been restored for Y-phase Hydraulic Pump of the breaker.

6 Tripping of 400 kV Hoody-Nelamangala line-2

23-04-2016 at 13:22 hrs

Line tripped on a B-phase to earth fault. Attempt for A/R was un-successful/ A/R could not be established from DR.

GI-2

Hoody (KPTCL) end:

As per FIR/TR, the line tripped at 13:32 hrs on B-E fault. KPTCL informed that DR & EL were not available at Hoody, and the same would be provided as part of R & M

works that were under progress. Nelamangala (KPTCL) end:

As per FIR/DR/EL/TR, the line tripped (in 3-ph) at 13:32:33.691 hrs on B-E fault due to DPR, Z1 operation.

It was informed by KPTCL that fault due to forest fire was observed near Nelamangala, at Tower location 8 & 9. KPTCL:

The fault was a B-E fault due to fire beneath B-ph conductor at Tower locations 8 & 9 (from Nelamangala end). The fault was cleared from Nelamangala end due to DPR, Z1 operation; and Hoody end cleared it due to DPR, Z2 (CAT) operation.

Remedial action: However, it was noticed that A/R was not attempted at any of the ends. So, they had proposed to check/ set

right the healthiness/ functionality of A/R scheme on 01.06.2016.

7 Tripping of 400kV Ambewadi-Ponda line-1

26-04-2016 at 12:13 hrs

FIR line tripped on a B-phase to earth fault. DR was not available for the event. Auto-reclose not enabled for line.

GI-2

Ambewadi (KPTCL) end:

As per FIR/TR, line tripped at 12:15 hrs. The type of fault and the type protection operated were not mentioned in either FIR/TR. KPTCL:

At Ambewadi: DPR started in zone-1, started phase BN, Fault current 840A, Dip in voltage 124.9kV; the line tripped on DEFR.

Reason: Suspected High resistive fault in the line. KPTL informed that DR triggered in DPR during operation of B/u protection. However DR & EL records pertaining

to this incident was not available in the relay.

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 30/37

IV. Line trippings due to tripping at one end / PLCC mal-operation

Sl. No.

Details of Event

Date & Time

Reason Category

1

Tripping of 400kV Khammam-Kalpaka line-2

22-04-2016 at 12:22 hrs

Line tripped at Kalpaka end only on receipt of Direct Trip & holding from Khammam end

GI-2

Khammam (PGCIL-SR1) end:

As per FIR, the line was kept holding from Khammam end. Kalpaka (APTRANSCO) end:

As per FIR, the line tripped at 12:22 hrs due to DT receipt from Khammam end

DR & EL not furnished. APTRANSCO:

This kind of tripping had occurred for the third time. And in the instant case, there were as many as 20 level changes in Channel-1, and 25 level changes in channel-2, which implied that a genuine problem could be in store at Khammam end.

To this, PGCIL-SR1 representative informed that PLCC at their was absolutely healthy; and there were no increments in Transmit & Receive counters at their end.

Recommendations: For the line under consideration, the following shall be carried out by APTRANSCO and PGCL (SR-I) in co-

ordination: End-to-end communication for DT/ permissive & other signals may be ensured by testing at both the ends. Healthiness of PLCC system components (hardware and software) at both ends shall be checked and faulty components

shall be repaired/ replaced.

2 Tripping of 400kV Ghanapur-Mamidapalli line

30-04-2016 at 16:40 hrs

Line tripped at Mamidipally end only on Direct Trip receipt from Ghanapur end

GI-2

Ghanapur (PGCIL-SR1) end:

As per FIR, the line was kept holding from Ghanapur end. Mamidipalli (TSTRANSCO) end:

As per FIR/EL, the line tripped at 16:40:26.267 hrs due to DT receipt from Ghanapur end.

DR not furnished.

Recommendations: For the line under consideration, the following shall be carried out by TSTRANSCO and PGCL (SR-I) in co-

ordination: End-to-end communication for DT/ permissive & other signals may be ensured by testing at both the ends. Healthiness of PLCC system components (hardware and software) at both ends shall be checked and faulty components

shall be repaired/ replaced.

*****

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 31/37

Single Line Diagram of 230 kV SP Koil SS of TANTRANSCO (Ref:I.1)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 32/37

Single Line Diagram of 220 kV Kalamassery SS of KSEB (Ref:I.2)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 33/37

Single Line Diagram of 230 kV Mywadi SS of TANTRANSCO (Ref:I.3)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 34/37

Single Line Diagram of 230 kV Mywadi SS of TANTRANSCO (Ref:I.3)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 35/37

Single Line Diagram of 220 kV Nagjheri PH of KPCL (Ref:I.4)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 36/37

Single Line Diagram of 230 kV Ingur SS of TANTRANSCO (Ref:II.6)

Annexure-III

Grid Occurrences discussed in the 54th

Meeting of PCSC held on 26th

May, 2016 37/37

Single Line Diagram of 400/ 220 kV Raichur TPS of KPCL (Ref:II.9)

Annexure-III

Meeting

No /

Index

Details of Event Date &

Time

Reason PCSC Recommendations Utility responsible

for

Implementation

Status of Recommendations

as on 10.06.2016

Remarks

Pending Implementation of PCSC Recommendations (up to 53rd)

42/II/3 Outage at

Regulapadu

station of

APTRANSCO

21-02-2015

at

00:49 hrs

Y-Ph Metering PT failed at 220KV

Ragulapadu Substation. Fault got

cleared by tripping of lines from remote

ends.

1. APTRANSCO to furnish the remedial measures taken in

consequent to the tripping incident along with the status of bus

bar protection and bus coupler at Regulapadu S/s.

2. A/R feature to be enabled on Regulapadu – Alipuira 220 kV

inter-state line.

APTRANSCO Mail received on 27-05-2015:

1)Failed metering PT was replaced with new PT.

2) 220kV Ragulapadu is a single bus system. Hence there is no provision

for bus coupler at Ragulapadu SS.

Mail received on 24-06-2015:

APTRANSCO Vide Ltr. Dt. 23/06/2015, requested KPTCL to furnish the

details of available tele protection equipments and details of the

equipments going to be procure for enabling the carrier aided protection

on 220KV Ragulapadu-Alipura line. Based on the KPTCL information

we will take further necessary action.

Mail recieved on 22-08-2015:

APTRANSCOhas planned to commission ABB make ETL-41 type PLCC

terminal along with NSD-50 type protection coupler at Ragulapadu end

towards Alipura. vide our Ltr Dt 23-07-2015, it is requested KPTCL to

arrange ABB make ETL-41 cabinet with NSD-50 type protection coupler

for establishing PLC communication between Alipura- Ragulapadu.

KPTCL Mail recieved on 23-01-2016:

KPTCL is ready with ETL-41 cabinet with NSD-50 type protection

coupler at Alipur end.

APTRANSCO mail received on 24-02-2016:

Protection coupler equipment is ready at Ragulapadu end. Wave trap

errection is pending at Ragulapadu end. To maintain the ground

clearenace structural modification works are going on for errection of

wave trap.

Pending

Complete outage of

220kV Yerraguntla

substation and

tripping of running

Units at

Rayalaseema TPS

52/I/2

(GD)

PendingYet to be informedAPGENCO 1. APGENCO to check associated logic for lube oil pump for

correct operation under transient low voltage conditions at

Rayalaseema TPS, Unit-1.

2. APGENCO to keep appropriate time delay/ fault ride through

delay (typically 2 sec) in VFD speed sensor relay at all its

generating Units including Rayalaseema TPS Units.

HV B-Ph Current transformer of

100MVA Power Transformer -1 failed

resulting into a bus fault on 220KV Bus-

1. Unit-1 and Unit-5 at RYTPS tripped

during the fault at Yerraguntla

substation

21-02-2016

at 10:39 hrs

Yet to be informed Pending

Andhra Pradesh

49/II/13

APGENCO Yet to be informed Pending

31-10-2015

at 03:30 hrs

Tripping of running

Units 1 & 3 at

Rayalaseema TPS

of APGENCO

While synchronizing Unit-5 with grid,

Bus bar protection of 220kV Bus-1

operated which resulted in de-

energization of 220kV Bus-1. This

resulted in tripping of running Unit-

1&Unit-3, 220kV lines Pulivedula-1,

Yeralaguntla-1, Chinakampalli-1,

Timmapura

In view of the availability of 25AX, APGENCO shall keep

synchronizing facility in auto-mode after getting it’s operation

verified by its OEM, M/s BHEL.

APGENCO

49/III/4 Tripping of 400kV

Krishnapatnam-

Chittoor line-1

19-10-2015

at 07:49 hrs

R-phase to earth fault had occurred in

line. Chittoor end tried for auto-reclose.

However, due to persistent fault, breaker

at Chittoor end tripped. Krishnapatnam

end relay did not try for auto-reclose and

gave a 3 phase trip as observed from

D.R

APGENCO to make A/R functional on all lines emanating from

Krishnapatnam TPS by 10th December, 2015.

Annexure-IV

Page 1 of 19

52/II/1 Tripping of 400 kV

Chittoor-

Sriperambadur line

01-02-2016

at 9:55 hrs

line tripped on operation of line reactor

protection at Sriperambadur end and

direct trip was sent to Chitoor. Buchholz

relay of line reactor of 400kV Chitoor-

Sriperambadur got operated at

Sriperabadur end.

APTRANCO to take steps to ensure that DR and EL are

configured for recording DT receipt event at their

400 kV Chittoor substation.

APTRANSCO Yet to be informed Pending

44/III/2 Tripping of 400kV

Ghanapur-

Mamidapalli

line

15-04-2015

at 2:03 hrs

Line tripped at Mamidapalli end only

and was holding at Ghanapur.

Overvoltage protection had operated at

Mamidapalli

TSTRANSCO to make DR functional at Mamidipalli TSTRANSCO TSTRANSCO informed vide their mail dated 24.06.15 that the existing

relays would be replaced with numerical relays in DPR works.

Pending

APTRANSCO mail received on 24-02-2016:

220KV chittoor substation is a old 220KV substation with single bus

operation. Bus bar protection has both main & checkzone are in service.

PendingDuring testing of DC earth leakage, DC

got extended to bus bar protection relay.

Hence bus bar protection operated and

tripped the 220KV BUS connected

transformers and feeders.

18-11-2015

at 11:20 hrs

Tripping of 220kV

Chittoor-Tiruvalam

50/II/14

Pending

47/II/6 Tripping of 400kV

Khammam-KTPS

line-2

30-07-2015

at 6:08 hrs

1. TSGENCO to check the reclaim time of A/R and set it at 25

sec at KTPS.

2. TSGENCO to carry out PLCC end-to-end testing in

coordination with PGCIL (SR-I) for KTPS – Khammam

line-2; retrofitting of Protection Coupler may be carried out based

on the test results.

TSGENCO

07-09-2015

at 2:58 hrs

Line tripped on operation of over-

voltage protection at Mahboobnagar and

direct trip received at N’sagar station.

DT receive was observed in DR and EL

of N’sagar station. D.R/EL of

Mahboobnagar was not furnished to

validate the overvoltage tripping

42/II/3 Outage at

Regulapadu

station of

APTRANSCO

21-02-2015

at

00:49 hrs

Y-Ph Metering PT failed at 220KV

Ragulapadu Substation. Fault got

cleared by tripping of lines from remote

ends.

1. APTRANSCO to furnish the remedial measures taken in

consequent to the tripping incident along with the status of bus

bar protection and bus coupler at Regulapadu S/s.

2. A/R feature to be enabled on Regulapadu – Alipuira 220 kV

inter-state line.

APTRANSCO Mail received on 27-05-2015:

1)Failed metering PT was replaced with new PT.

2) 220kV Ragulapadu is a single bus system. Hence there is no provision

for bus coupler at Ragulapadu SS.

Mail received on 24-06-2015:

APTRANSCO Vide Ltr. Dt. 23/06/2015, requested KPTCL to furnish the

details of available tele protection equipments and details of the

equipments going to be procure for enabling the carrier aided protection

on 220KV Ragulapadu-Alipura line. Based on the KPTCL information

we will take further necessary action.

Mail recieved on 22-08-2015:

APTRANSCOhas planned to commission ABB make ETL-41 type PLCC

terminal along with NSD-50 type protection coupler at Ragulapadu end

towards Alipura. vide our Ltr Dt 23-07-2015, it is requested KPTCL to

arrange ABB make ETL-41 cabinet with NSD-50 type protection coupler

for establishing PLC communication between Alipura- Ragulapadu.

KPTCL Mail recieved on 23-01-2016:

KPTCL is ready with ETL-41 cabinet with NSD-50 type protection

coupler at Alipur end.

APTRANSCO mail received on 24-02-2016:

Protection coupler equipment is ready at Ragulapadu end. Wave trap

errection is pending at Ragulapadu end. To maintain the ground

clearenace structural modification works are going on for errection of

wave trap.

Pending

52/I/5

(GD)

Complete outage of

220kV Regulapadu

substation of

APTRANSCO

02.03.2016

at 14:32 hrs

220KV R-ph Metering PT failed at

220KV Regulapadu Substation.

APTRANSCO to furnish the Equipment Failure Report for the R-

ph CT blast to Power System Engg &

Technolgy Divison (PSETD) of Central Electricity Authority with

a copy marked to SRPC.

TSTRANSCO Yet to be informed TSTRANSCO to furnish a detailed report on the tripping event

along with remedial measures taken to PCSC forum.

Telangana

APTRANSCO Yet to be informed

Pending

Y-phase to earth fault had occurred in

line. From Khammam end DR it was

observed that the relay after dead time

tried for auto-reclose. The fault was

persisting and relay gave a single phase

trip instead of a 3 phase trip after

1.25sec. R& B pole voltage dip after 2

sec possibly due to operation of pole

discrepancy. Auto-reclose close

command observed after 2.5 seconds

and all poles got closed.

1. APTRANSCO to furnish SLD of 220/132 kV Chittoor SS,

2. APTRANSCO to confirm whether 220 kV side is on single-

bus operation with only one main-zone. If so, APTRANSCO shall

examine the feasibility of providing split-bus operation or

multiple main-zones for bus bar protection, and take necessary

steps to implement it.

APTRANSCO

Yet to be informed Pending

48/II/5 Tripping of 400kV

Nagarjunsagar-

Mahboobnagar line

Annexure-IV

Page 2 of 19

48/III/4 Tripping of 220kV

Gajwel-

Shankarapally line

20-09-2015

at 2:24 hrs

line tripped at Gajwel end on R-Phase to

ground fault. Reason for non-auto

reclose could be established as DR and

EL of both ends were not furnished

TSTRANSCO to furnish a detailed report on the tripping event

along with remedial measures taken to PCSC forum.

TSTRANSCO Yet to be informed Pending

51/IV/1 Tripping of 400kV

Gajwel-Hyderabad

29-12-2015

at 6:11 hrs

and 7:11 hrs

Line tripped at Gajwel end only due to

suspected PLCC mal-operation at

Gajwel end

TSTRANSCO to check the integrity of all DR’s and EL’s, and

sort out communication related issues at 400 kV Gajwel SS.

TSTRANSCO Yet to be informed Pending

52/I/6 Complete outage of

220kV

Malyalapalli station

of TSTRANSCO

10-03-

2016at

18:41 Hrs

CT failure occurred in 220kV

Ramagundam-Malyalapalli line-1 at

Malyalapalli end. The CT failure

resulted into a Bus fault. All 220kV

lines and transformers at Malyalapalli

station tripped during the incident.

TSTRANSCO to furnish the Equipment Failure Report for the R-

ph CT blast to Power System Engg & Technolgy Divison

(PSETD) of Central Electricity Authority with a copy marked to

SRPC.

TSTRANSCO Yet to be informed Pending

Karnataka

07-09-2015

at 2:58 hrs

Line tripped on operation of over-

voltage protection at Mahboobnagar and

direct trip received at N’sagar station.

DT receive was observed in DR and EL

of N’sagar station. D.R/EL of

Mahboobnagar was not furnished to

validate the overvoltage tripping

TSTRANSCO Yet to be informed TSTRANSCO to furnish a detailed report on the tripping event

along with remedial measures taken to PCSC forum.

Pending48/II/5 Tripping of 400kV

Nagarjunsagar-

Mahboobnagar line

Annexure-IV

Page 3 of 19

Mail recieved on 28-05-2015:

1) e-NIT floated on 28.07.2014 for procurement of Numerical distance

relays & GPS. As there is change in scope of work and quantity of relays

by more than 25%, which is not permitted as per KTPP act. Hence, tender

cancelled and refloated on 05.05.2015 with revised scope of work and

revised PQR.

2. However, as per the recommendations of PSAG, Relays were

temporarily rearranged, replaced and wired up. testing & commissioning

shall be completed with the assistance of KPTCL.

Mail recieved on 07-07-2015:

1. Cover -1 of the bid is scheduled for open eing on 25.06.2015.

2. As per the recommendations of PSAG, Relays were temporarily

rearranged. testing & commissioning completed with the assistance of

KPTCL.

Mail recieved on 07-09-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed.

Obtaining of Administration approval to place P.O is in progress.

However, as per therecommendationsof PSAG-10, Relays

weretemporarilyrearranged.Testing & commissioning completed with the

assistanceofKPTCL.

Mail recieved on 21-10-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed. LOA's

issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Mail recieved on 23-11-2015:

LOA's issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Engineering work is in progress.

Status informed during Special Meeting held on 03.06.2016:

LOA’s issued to M/s Schneider on 08.10.2015. Inspection of relays

completed and received at site. DI issued for all balance materials except

furnitures.

PendingKPCL1. The PCSC forum requested KPCL to speed up the

installation of Numerical Distance Protection relay in Kadra

–Kaiga and Kodasalli –Kaiga.

2. The PCSC forum requested KPCL to submit the

implementation status of PSAG-10 recommendations within a

week’s time.

A fault had occurred in 220 kV Kadra

and Kodasalli. As A result, de-

energization of 220kV bus occurred at

Kadra and Kodasalli.

13-11-2014

at 19:31hrs

GD-1 at Kadra and

Kodasalli hydro

power station

38/GD/3.5

Mail recieved on 28-05-2015:

1. e- Tender folated for the retrofit of existing static relays with

Numerical version for lines M.nagar,M.bad,ICT-1 & 2 -Technical Bid &

Price bid opened . Bid evaluation and approval to place P.O. is in

progress.

2. Retrofit of existing bus bar (CAG-34) with numerical version -

Budgetetory offers obtained and is in process.

3. Order placed on M/s Siemens to replace relays. The work will be

completed by May - 2015.

Mail recieved on 07-07-2015:

1. Retrofit of existing static relays with Numerical version for lines

M.nagar, M.bad and ICT- 1 & 2 -- Inspection of the Numerical relays at

M/s Siemens works completed on 11-06-2015 and Dispatch clearance has

been issued. Materials received.

2. Retrofit of existing bus bar (CAG-34) with numerical version –

Budgetary offers obtained and is under process.

Mail recieved on 07-09-2015:

1. Replacement of Old electromagnetic relays with Numerical relays has

been completed for RTPS-BTPS line & commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with

numerical relays.

The retrofitting of electromechanical relays with Numerical version for

ICT-1, ICT-2 and Munirabad line has been completed.

Retrofitting work for Mehaboobnagar line is pending. Awaiting for line

shutdown.

2. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd.

Chennai for retrofitting of relays for all 220kV lines at RTPS.

3. Retrofit of existing bus bar(CAG-34) with numerical version–

Budgetary offers obtained and is under process.

Mail recieved on 21-10-2015 and 23-11-2015:

1) Replacement of Old electromagnetic relays with Numerical relays has

been completed for RTPS-BTPS line & commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with

numerical relays.

The retrofitting of electromechanical relays with Numerical version for

the following lines/ICTs have been completed/commissioned as follows:

a) ICT-2 –Commissioned on 01-08-2015

b) ICT-1 ---Commissioned on 08-08-2015

c) Munirabad line--- Commissioned on 16-08-2015.

d) Mehaboobnagar line-- Commissioned on 09-09-2015.

2. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd.

Chennai for retrofitting of relays for all 220kV lines at RTPS.

3. Retrofit of existing bus bar(CAG-34) with numerical version–

Budgetary offers obtained and is under process.

PendingRTPS Tripping

incidents and the

Spl meeting held at

RTPS on 13th and

14th March 2014

30/I/A KPCLThe PCSC forum recommended for replacement of existing

electromechanical relays with Numerical relays. Spl meeting held at RTPS on 13

th and

14th

March 2014

Mar-14

Annexure-IV

Page 4 of 19

Mail recieved on 28-05-2015:

1) e-NIT floated on 28.07.2014 for procurement of Numerical distance

relays & GPS. As there is change in scope of work and quantity of relays

by more than 25%, which is not permitted as per KTPP act. Hence, tender

cancelled and refloated on 05.05.2015 with revised scope of work and

revised PQR.

2. However, as per the recommendations of PSAG, Relays were

temporarily rearranged, replaced and wired up. testing & commissioning

shall be completed with the assistance of KPTCL.

Mail recieved on 07-07-2015:

1. Cover -1 of the bid is scheduled for open eing on 25.06.2015.

2. As per the recommendations of PSAG, Relays were temporarily

rearranged. testing & commissioning completed with the assistance of

KPTCL.

Mail recieved on 07-09-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed.

Obtaining of Administration approval to place P.O is in progress.

However, as per therecommendationsof PSAG-10, Relays

weretemporarilyrearranged.Testing & commissioning completed with the

assistanceofKPTCL.

Mail recieved on 21-10-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed. LOA's

issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Mail recieved on 23-11-2015:

LOA's issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Engineering work is in progress.

Status informed during Special Meeting held on 03.06.2016:

LOA’s issued to M/s Schneider on 08.10.2015. Inspection of relays

completed and received at site. DI issued for all balance materials except

furnitures.

PendingKPCL1. The PCSC forum requested KPCL to speed up the

installation of Numerical Distance Protection relay in Kadra

–Kaiga and Kodasalli –Kaiga.

2. The PCSC forum requested KPCL to submit the

implementation status of PSAG-10 recommendations within a

week’s time.

A fault had occurred in 220 kV Kadra

and Kodasalli. As A result, de-

energization of 220kV bus occurred at

Kadra and Kodasalli.

13-11-2014

at 19:31hrs

GD-1 at Kadra and

Kodasalli hydro

power station

38/GD/3.5

ICT tripped due to operation of Over

current and Earth fault relay

14-01-2015

at 1:09

hrs

KPCL to check the possibility of providing line differential

protection between RTPS and Yermarus stations.

KPCL

GD-1 at 220kV

Kadra power

Station of KPCL

16-02-2015

at 12:56 hrs

41/I/1

Tripping of

400/220kV ICT-1

at

BTPS

43/II/14

Pending

KPCL vide their mail dated 07.07.2015 informed that revised relay

settings would be incorporated in co-ordination with KPTCL.

Mail received on 07-09-2015 , 21-10-2015 and 23-11-2015:

Revised relay settings are awaited from KPTCL.

Revised relay settings furnished by KPTCL will be incorporated in co-

ordination with KPTCL shortly.

Pending

KPCL Mail received on 28-05-2015:

1. Main-2 relays already installed and commissioned.

2. DC fuses are intact. Till date no such incidence occurred.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Mail received on 07-07-2015 , 21-10-2015 and 23-11-2015:

1. Completed.

2. Completed.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Triggering incident was B-phase to earth

fault had occurred in 220kV Kadra-

Kodasalli line. Line tripped from

Kodasalli end only. 220kV Kaiga-Kadra

tripped in Zone-3 from Kaiga end.

Tripping of evacuating lines caused bus

shut down at Kadra hydro station.

1. KPCL to make functional the Main2 (EPAC) relay with

the help of KPTCL at the earliest.

2. KPCL to investigate the reason for DC fuse fail during

transient fault in 220kV Kadra-Kodasalli line including the

testing/ checking of DC supply cables, breaker control cables, and

trip coils.

3. KPCL to ensure supply for Main-1& Main-2 protections,

Trip Coils (TC1, TC2) from separate battery banks.

Annexure-IV

Page 5 of 19

49/II/15 Trippings at

Raichur TPS

12-11-2015

at 00:30 hrs

Running Unit-4, 5 and Unit-8 and

400kV RTPS-Yeramaras TPS feeder got

tripped due to de-energization of both

400kV Bus-1&2 at Raichur TPS

1. KPCL to carry out hot-line washing of RTPS-connected lines

regularly to avoid trippings due to fog and dust.

2. KPCL may see the feasibility of providing breaker flashover

protection at RTPS, and implement the same if possible.

KPCL Status informed during Special Meeting held on 03.06.2016:

1. Hot line washing was done previously.tender process is on for silicon

coating of insulators.

Pending

PendingMail received on 21-10-2015:

1) Anti-pumping contactors of all the nine 220KV Lines are in circuit and

tested periodically during AOH works of lines along with other

protections.

2) Completed.

3) Possibility to use both the 220kV buses as main bus under normal

operation is under review.

Mail recieved on 23-11-2015:

1) Completed

3) Two bus operation for 220kV buses : In place of existing CT switching

relays, High speed manual heavy duty change over switch of sufficient

current capacity will be retrofitted to all feeders at 220kV station and

same will be operated manually during changeover of feeder by one bus

to the other and this arrangement may facilitate to put both buses in

service. Time required for this retrofit is around 90days . However, this

work will be taken up only after retrofitting of electromagnetic relays with

numerical relays for Main-2 protection of all 220kV lines, for which work

is in progress.

KPCL1. KPCL to check the operation of anti-pumping relay on 220 kV

side and keep it in healthy condition.

2. KPCL to provide manual reset to the 220 kV side master trip

relay.

3. KPCL to use both the 220 kV buses as main buses under

normal operation, and should go for single bus operation only

during emergencies.

07-06-2015

at 01:35 hrs

Trippings at 220kV

Raichur TPS

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

1.Existing Back up relays will be replaced by numerical type distance

relays.Procurement is in tendering stage.

2. Completed.

3. Completed.

KPTCL Mail recieved on 23-01-2016:

1. Existing back up relays will be replaced by Main-2 protection. LOI

issued M/s Alstom for taking up the works.

KPTCL Mail Recieved dated 25-05-2016:

Under the Scope of R&U. The work will be taken up by M/s Alstom

shortly.

KPTCL1. PCSC forum recommended KPTCL to replace the old static

distance protection relays with numerical relays.

2. PCSC forum also requested KPTCL to provide a broken

conductor alarm indication in Control Room.

3. Standing instruction needed to be given to the all substation

personnel for not changing the relay settings without approval of

RT/MRT wing.

Mail received on 27-05-2015 & 29-07-2015:

1. C&R panels of 500MVA ICT 1&2 will be replaced under scheduled

R&M works.

2. O&M personnel are instructed to take sufficient care in order to avoid

unwarrented trippings. --- Completed.

KPTCL mail received on 23-01-2016:

New C&R panels(with numerical relays) erected for 500MVA ICT-1 &2

under R&M work, which will be commissioned shortly.

KPTCL mail received on 25-05-2016:

New C&R panels(with numerical relays) erected for 500MVA ICT-1 &2

under R&M work, which will be commissioned shortly.

KPTCL1. PCSC forum recommended KPTCL to replace the relay with a

different make.

2. KPTCL was also requested to train the O&M personnel

adequately before performing any maintenance works to avoid

such unwanted trippings.

Pending

Fault had occurred in 220kV

Mahalingapura-Narendra line-2. Due to

the

failure of relay operation at

Mahalingapura,

breakers at remote end tripped which

resulted in bus dead condition.

25-10-2014GD-1 at

Mahalingapura

Substation of

KPTCL

38/GD/3.1

Suspected mal-operation of 220kV side

Rphase

over current relay

01-12-2014Tripping of

400/220kV

ICT-2 at Hoody

substation of

KPTCL

46/II/21

Pending

39/I/5

Annexure-IV

Page 6 of 19

PendingMail recieved on 29-07-2015:

Carrier protection is being restored for 220kV Sedam-Tandoor line at

Sedam end. After restoring the carrier protection , AR will be enabled.

KPTCL mail recieved on 23-01-2016:

Carrier protection is being restored for 220kV Sedam-Tandoor line at

Sedam end. After restoring the carrier protection , AR will be enabled.

KPTCL mail recieved on 25-05-2016:

SEE,SCADA to update the latest status

Mail received on 28-04-2015:

Procurement of Bus bar and LBB protection is in the final tendering

stage. 2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled.

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

KPTCL mail received on 23-01-2016:

1. Bus bar protection panels pocured and erected at Sedam. Wiring ,

testing ,commissioning is being taken up.Planned to complete by April

2016.

2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled after restoration of PLCC.

PendingKPTCL 1. KPTCL to provide Bus bar and LBB protections for 220

kV bus at Sedam S/s.

2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur

inter-state line.

R-Phase to ground fault occurred on

220kV Sedam-Shahpur line. Fault not

cleared from Sedam end due to stuck-

breaker condition. While the Sedam-

Sahapur line tripped from Shahapur end

in Zone-1, the other 220 kv lines from

Sedam tripped at remote ends in Zone-2.

This caused complete outage of 220kV

Sedam substation.

Triggering incident was B-phase to earth

fault in 220kV Ambewadi- Nagzari line-

1. B-pole of breaker did not open at

Ambewadi end. LBB protection not

available at Ambewadi end. All elements

tripped on Zone-2 from remote ends.

22-12-2014

at 21:22 hrs

GD-1 at 220kV

Ambewadi Station

of KPTCL

27-01-2015

at 8.00 hrs

Complete outage at

220kV Sedam

Substation of

KPTCL (GD-1)

Mail received on 28-04-2015:

1. In view of operating 220kV Ambewadi SS in split bus mode, action is

being taken up by KPTCL. Problem in the 220kV bus coupler breaker is

attended and isolator overhauling work is under progress. Spilt bus

operation at Ambewadi will be made possible at the earliest.

2. ICT protection system at Ambewadi and trippings occured at Supa GS

during the instance is checked up and remedial measures already

furnished in this regard. ---- Completed

Mail recieved on 29-07-2015:

1. Action is being taken by KPTCL for operating Ambewadi in split bus

mode. Problem in bus coupler breaker is attended.Isolator overhaulling

work is completed.PTs are already provided to 220kV Bus-II. After

commissioning of Bus-II PTs, Ambewadi can be operated in split bus

mode. Pending works will be completed within a months time.

KPTCL mail recieved on 23-01-2016:

Bus-II PTs yet to be commissioned.Planned to complete before end of

April-2016.

Pending1. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore the possibility of having split

bus operation at Ambewadi and submit the details of the same to

PCSC forum.

2. KPTCL shall provide the details of the tripping of Supa hydro

station connected downstream from 110 kV bus.

KPTCL40/I/1

41/I/4

KPTCL was requested to explore the possibility of providing

A/R feature to this line and submit the remedial measures to the

PCSC forum.

Line tripped on Yphase to earth fault

from both the ends

20-12-2014

at 22:20 hrs

220kV Sedam-

Tandur line

40/IV/1 KPTCL

Annexure-IV

Page 7 of 19

47/III/8 Tripping of 220kV

Ambewadi-Ponda

line-2

02-08-2015

at 13:20 hrs

Line tripped on a transient fault in B-

phase. There is no

provision for auto reclose.

PendingYet to be informed

Yet to be informed Pending

Mail received on 27-05-2015:

1. Carrier protection is put in to service. AR will be enabled at the

earliest.

Mail received on 29-07-2015:

1. Action is taken for enabling AR for Mudashinge and Talandage lines.

Work is scheduled during first week of August 2015.

KPTCL mail received on 23-01-2016:

1) Replaced existing VXL by ABB make C&R panel for both interstate

lines on 21.04.2015. The ABB Engineer visited 220KV Chikodi on

05.11.2015 for enabling AR system to existing ABB make REL511 relay

for both interstate line, but AR system not enabled due to internal cards

faulty. Hence action is being taken to replace the ABB,REL511 distance

relays within a months time.

Pending

42/I/2

(GD)

42/II/2

KPTCL to activate non-directional Over Current protection with a

time delay of 600-800 msec for Fuse

failure condition at Lingasugur.

Tripping of Unit-

1&2

along with

400/220kV

ICT-2 at Raichur

TPS

06-08-2015

at 4:51 hrs

KPTCL

KPTCL1. KPTCL to provide A/R feature on the 220 kV Chikkodi –

Talandage, and 220 kV Chikkodi –Mudashinge inter-state lines.

2. KPTCL to carry out E/F relay coordination for Chikkodi -

Talandage and Chikkodi –Mudashinge lines in coordination with

Maharashtra.

Lines tripped during test charging

220kV

Chikodi-Belgaum line-2 from Chikodi

end.

20-02-2015

at

06:40 hrs

Tripping of 220kV

Chikodi-

Talandage and

220kV Chikodi-

Mudshingi line

47/II/13

Till A/R is put into service on Ambewadi-Ponda line-1, KPTCL

to reduce Zone-2 time setting to zero sec. at Ambewadi end.

1. KPTCL to provide Bus Bar protection and LBB protection at

Sedam S/s and furnish the status of their implementation to PCSC

forum.

2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur

inter-state line.

Pending1. KPTCL shall provide A/R feature on Ambewadi – Ponda 220

kV D/C inter-state line.

2. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore the possibility of having split

bus operation at Ambewadi and submit the details of the

same to PCSC forum.

KPTCL

KPTCL

Fault in 220kV Ambewadi-Nagjheri line-

2

12-03-2015

at 7:51 hrs

Complete outage of

220kV Ambewadi

substation of

KPTCL

220kV RTPS-Lingasugur line-2 tripped

at TPS end on operation of distance

protection zone-1. 400/220kV ICT-2 got

tripped on operation of earth fault

protection. 220kV RTPS-Lingasugur

line-1&3 tripped on distance protection

zone-2 and zone-3 respectively. Due to

tripping of ICT-2, the running units got

overloaded and it was mentioned that

under frequency occurred as units are on

load control. The Units got tripped on

under frequency.

Fault occurred in 220kV Sedam-Shahpur

line

Pending

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

Mail received on 27-05-2015:

1. Bus Bar protection will be provded under R&U.

2. A/R yet to be enabled.

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

KPTCL15-02-2015

at 14:24 hrs

Complete outage of

220kV Sedam

substation of

KPTCL

42/I/1

(GD)

Annexure-IV

Page 8 of 19

47/III/10 Tripping of 220kV

Ambewadi-Ponda

line-1

08-08-2015

at 10:51

hrs and 09-

08-2015 at

11:15 hrs

Line tripped on a B-phase to earth fault.

Line tripped as there is no provision for

auto-reclose

47/III/12 Tripping of 220kV

Ambewadi-Ponda

line-1

17-08-2015

at 13:20 hrs

Line tripped on a transient fault . There

is no provision for Auto reclose.

KPTCL mail received on 25-05-2016:

Presentl 220kV Nelamangala -Hoody(i.e. nelamangala-Peenya-Hebbal -

Hoody line is made LIILO at Yelahanka sub station and breaker at

Peenya is kept open, necessary modification in distance relay settings

adopted for new configuration.

Pending

PendingYet to be informed

220kV Ambewadi-Nagjheri line-2

tripped on B-phase to earth fault. This

resulted in loss of supply to 220kV

Ambewadi bus. 220kV Ambewadi-

Ponda line-1&2 were hand tripped after

deenergization of bus at Ambewadi.

KPTCL to fast-track providing A/R on all 220 kV lines

emanating from Ambewadi SS to prevent Station shut-down on

temporary faults.

KPTCL

48/I/2

(GD)

Complete outage of

220kV Peenya

Substation in

Karnataka

27-09-2015

at 4:23:17

hrs

All connected 220kV lines and

transformers were taken on 220kV

North bus as South bus was under shut

down for conversion of strung bus to

rigid bus and isolator replacement under

R&M works. Failure of HV side Y

phase CT of 150MVA Transformer-3

occurred at Peenya Substation which

resulted in operation of Differential and

HV REF protection. The failure of CT

also resulted in a 220kV bus fault in

North Bus.

KPTCL to revise distance relay settings at Nelamangala end for

220 kV Nelamangala – Hebbal - Peenya line – 1 for the effective

line length of 17 km. These new settings can be appropriately

reviewed as and when the tie-arrangement at Hebbal is done away

with.

KPTCL

Outage of 220kV

Ambewadi station

in Karnataka

48/I/3

(GD)

Till A/R is put into service on Ambewadi-Ponda line-1, KPTCL

to reduce Zone-2 time setting to zero sec. at Ambewadi end.

KPTCL

KPTCL mail received on 23-01-2016:

Will be complied in a months time.

Pending30-09-2015

at 10:41 hrs

Annexure-IV

Page 9 of 19

48/I/4

(GD)

Complete outage of

220 kV HSR

substation of

Karnataka

06-10-2015

at 16:32 hrs

All connected 220kV lines at 220kV

HSR substation i.e. Somanahalli, EPIP,

Hoody and Nagnathapura tripped during

the incident. Triggering incident was

fault in 220kV HSR-EPIP line

KPTCL to review distance relay settings at Naganathpura SS in

view of LILO arrangement at HSR Lay-out.

KPTCL KPTCL mail received on 23-01-2016:

ABB make REL 670 type distance relays provided to Somanahalli and

hoody lines. Planned to commission within 10 days.

KPTCL Mail recieved dated 25-05-2016:

New REL 670 relays erected in the panel. Testing and commissionng will

be done within a month's time.

Pending

52/I/3

(GD)

Complete outage of

220kV Shimoga

substation

22-02-2016

at 15:03 hrs

220kV Bus Bar protection operated

during failure of R phase CT in DVG-2

line bay.

KPTCL to operate 220 kV Shimoga on multi-bus operation under

normal conditions, put it on single-bus operation only under

emergency conditions.

KPTCL Yet to be informed Pending

Yet to be informed Pending

220kV lines from Nagjheri power house

started tripping from 11:00 hrs due to

fault in lines. The sequence of tripping

is shown in SOE list. At 12:33 hrs,

220kV Narendra-Ambewadi lines-1&2

got tripped which resulted in loss of

evacuation path to Nagjheri station

resulting in tripping of running Units

and complete outage at Nagjhheri power

station. 220kV Ambewadi station also

got de-energized due to tripping of

source feeders i.e. 220kV Narendra-

Ambewadi-1&2 and 220kV Nagjheri-

Ambewadi-1&2.

1. To avoid tripping of transmission lines on transient faults,

KPCL/ KPTCL is recommended to carry out periodic patrolling

of lines, and ensure their proper maintenance by carrying out

jungle/ bushing clearance and trimming of tree branches within

the RoW of transmission lines as per the SRPC transmission line

patrolling guidelines (available under the menu item "All

Uploads Operation Miscellaneous Transmission Line

Patrolling Protocol / Guidelines for Southern Region" on SRPC

website).

2. KPCL/ KPTCL to review operation of SPS at NPH for

functionality (reduction of generation with tripping of evacuating

lines) and healthiness.

3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into

service if more than 200 MW generation from Kali Complex

(with Nagheri Contribution not less than 50 MW) is ensured on

sustained basis.

KPCL/ KPTCL Status informed during Special Meeting held on 03.06.2016:

1. KPTCL informed that the matter had been taken up with concerned

Line Operation and Maintenance wing to carry out corridor clearance and

maintenance as per schedule to avoid frequent line faults in this corridor.

A letter had also been addressed to Chief Engineer, Bhagalkot zone, to

ensure lines in & around Kali complex are maintained in healthy

condition. --- Completed

2. KPTCL assurd that the final modified SPS would be implemented at

Nagjheri PH at the earliest. ------ Pending

3. KPCL informed that Nagjhari- Kodasalli Lines 1 & 2 had been kept in

service since 23.05.2016 @ 08.06hrs. ---- Completed

KPTCL Mail received dated 25-05-2016:

SEE, RTC, Bangalore to update the status

Complete outage of

220kV Ambewadi

Substation of

KPTCL

29.10.2015

at 14:34 hrs

1. KPCL to provide A/R on all 220 kV lines emanating from

Nagjheri PH.

2. KPTCL to provide A/R on all 220 kV lines emanating from

Ambewadi SS.

KPTCL

Failure of Lightning Arrestor of Y-phase

Line Reactor of 400kV Guttur-Hiriyur

line-1 and line tripped on distance

protection Zone-1. Bus-bar protection of

400kV Bus-2 at Guttur substation also

got operated during the event sensing

this through fault. 400/220 kV ICT-1 &

2 at Guttur, 400kV Kaiga-Guttur-2,

400kV

Guttur-Narendra-2, 400kV Guttur-

Hiriyur-2 and 400kV Guttur-Munirabad

which are on 400kV Bus-2 got tripped

during the incident. 400kV Guttur-

Narendra-1 which was on Bus-1 also

tripped at the same time.

51/II/21 Multiple tripping at

400kV Guttur sub-

station

17-01-2016

at 18:53 hrs

KPTCL 1. KPTCL to configure all DR’s and EL’s at 400 kV Guttur SS so

that they will also get triggered for BBP operation.

2. KPTCL to ensure time-synchronization of all DR’s and EL’s

with GPS at their 400 kV Guttur SS.

220kV Nagjheri-Ambewadi line-1

tripped at 13:33 hrs due to B phase to

earth fault. Ambewadi was radially fed

from Nagjheri power station through

220kV Nagjheri-Ambewadi line-2.

Tripping of this line caused 220kV Bus

shut down at Ambewadi and remaining

lines and transformers were hand

tripped

49/I/1.3

(GD)

Complete outage of

220kV Peenya

Substation of

KPTCL

53/I/1 Pending16-03-2016

at 11:39 Hrs

22-02-2016

at 12:36 hrs

51/I/3

Pending

Pending

220kV Peenya-Nelamangala-3 tripped

on B-E fault at both ends. At the same

time, 220kV Peenya-Nelamangala-4

tripped on R-Y fault only at

Nelamangala end, and was in service

from Peenya end. Due to tripping of

these two lines, 220kV Peenya-

Nelamangala-2 tripped on overcurrent

protection.

KPTCL to furnish a report on the tripping of 220 kV Peenya-

Nelamangala line-4 Nelamangala detailing the remedial measures

taken including the settings adopted for Z1B (Zone extension)

and Power Swing Block.

KPTCL KPTCL Mail received dated 25-05-2016:

SEE, RTC, Bangalore to update the status

Complete outage of

220kV Nagjheri

power station and

220kV Ambewadi

substation of

KPTCL

Annexure-IV

Page 10 of 19

53/II/1 Tripping of ICT-3

at Raichur

Substation

15-03-2016

at 12:28 hrs

ICT-3 tripped due to operation of back-

up earth fault protection during fault in

220kV RTPS-Raichur line-1.

KPCL/ KPTCL to check the ICT’s back-up (high-set) protection

settings, and ensure that they operate with a time delay of 100

msec.

KPCL/KPTCL KPTCL Mail Recieved dated 25-05-2016:

SEE,SCADA to update the status of healthiness of carrier protection of

220kV RTPS-Raichur 1 &2 lines

Pending

220kV lines from Nagjheri power house

started tripping from 11:00 hrs due to

fault in lines. The sequence of tripping

is shown in SOE list. At 12:33 hrs,

220kV Narendra-Ambewadi lines-1&2

got tripped which resulted in loss of

evacuation path to Nagjheri station

resulting in tripping of running Units

and complete outage at Nagjhheri power

station. 220kV Ambewadi station also

got de-energized due to tripping of

source feeders i.e. 220kV Narendra-

Ambewadi-1&2 and 220kV Nagjheri-

Ambewadi-1&2.

1. To avoid tripping of transmission lines on transient faults,

KPCL/ KPTCL is recommended to carry out periodic patrolling

of lines, and ensure their proper maintenance by carrying out

jungle/ bushing clearance and trimming of tree branches within

the RoW of transmission lines as per the SRPC transmission line

patrolling guidelines (available under the menu item "All

Uploads Operation Miscellaneous Transmission Line

Patrolling Protocol / Guidelines for Southern Region" on SRPC

website).

2. KPCL/ KPTCL to review operation of SPS at NPH for

functionality (reduction of generation with tripping of evacuating

lines) and healthiness.

3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into

service if more than 200 MW generation from Kali Complex

(with Nagheri Contribution not less than 50 MW) is ensured on

sustained basis.

KPCL/ KPTCL Status informed during Special Meeting held on 03.06.2016:

1. KPTCL informed that the matter had been taken up with concerned

Line Operation and Maintenance wing to carry out corridor clearance and

maintenance as per schedule to avoid frequent line faults in this corridor.

A letter had also been addressed to Chief Engineer, Bhagalkot zone, to

ensure lines in & around Kali complex are maintained in healthy

condition. --- Completed

2. KPTCL assurd that the final modified SPS would be implemented at

Nagjheri PH at the earliest. ------ Pending

3. KPCL informed that Nagjhari- Kodasalli Lines 1 & 2 had been kept in

service since 23.05.2016 @ 08.06hrs. ---- Completed

Tamil Nadu

PendingYet to be informed 1. KPCL to furnish a report on the reasons for Unit-6 tripping at

Nagjheri PH.

2. KPCL/ KPTCL to modify suitably the SPS at Nagjheri Power

House such that it would also factor in the over loading of

Ambewadi-Narendra lines.

3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into

service if more than 200 MW generation from Kali Complex

(with Nagheri Contribution not less than 50 MW) is ensured on

sustained basis.

KPCL/ KPTCL

Pending TANTRANSCO to take suitable measures like installing more

stub-towers along 230 kV OK Mandapam – Myvady line to avoid

excessive sag due to over-loading.

TANTRANSCO

1. TANTRANSCO to ensure correctness of operation of LBB

relays at SP Koil.

2. TANTRANSCO & MAPS to furnish their respective

compliance report of the recommendations of to-be-conducted

PSAG-14 meeting at MAPS, Kalapakkam.

TANTRANSCO

TANTRANSCO vide their mail dated 24.06.15 informed that different

relays in Main-I & Main-II would be ensured at the earliest.

Mail recieved on 24-07-2015 ,19-02-2016 and 24-03-2016:

Different relays in Main-I & Main-II will be ensured.

Mail received on 27-04-2016:

TANTRANSCO: Not feasible in the existing SAS sub stations. Hence,

exemption may be given for these sub stations.

Mail received on 20-05-2016:

As discussed in the 52nd PCSC meeting, Swapping of Relays between

two stations is not feasible in the existing SAS sub stations. Hence,

exemption may be given for these sub stations.

Pending

Complete outage of

S.P.Koil station of

TANTRANSCO

and generation loss

at MAPS

TANTRANSCO Mail received on 19-02-2016:

LBB scheme will be checked to ensure correctness of operation while

availing Line Clear.

TANTRANSCO and MAPS mail received on 25-01-2016:

Complaince report was submitted with respect to the recommendations

given in the Minutes of PSAG-14 Meeting.

TANTRANSCO mail received on 24-03-2016 ,27-04-2016 and 20-05-

2016:

Complaince report was submitted on 25.01.2016 with respect to the

recommendations given in the Minutes of PSAG-14 Meeting.

TANTRANSCO Mail received on 19-02-2016, 24-03-2016 and 27-04-

2016:

230kV Othakalmandapam - Myvadi feeder will be made LILO at Kongal

Nagar. Line restringing will be carried out along with the above proposal.

Mail Received on 20-05-2016:

230kV Othakalmandapam - Myvadi feeder will be made LILO at Kongal

Nagar. Line restringing will be carried out along with the above proposal.

43/II/5 Tripping of 400kV

Alamathy-

SVChatram line-

1&2

and 400/230kV

ICT

at S.V.Chatram

29-03-2015

at

15:29 hrs

TANTRANSCO was requested to swap the relays between two

stations, so that

Main-1 and Main-2 will be of different make at each station.

TANTRANSCOLine-2 tripped on R-phase to earth fault.

Line autoreclosed at SVChatram end

and failed to reclose at Alamathy end.

Bphase to earth fault in line-1. Line tried

for A/r but due to permanent fault line

did not reclose. ICT tripped on

operation of over flux protection.

53/I/3

(GD)

Complete outage of

220kV Ambewadi

station of KPTCL

and 220kV

Nagjheri of KPCL

18-03-2016

at 14:40 hrs

Ambewadi Narendra line-2 tripped on

fault and 220kV ambewadi Narendra

line-1 tripped due to over-loading.

Running Units at Nagjheri also tripped

during the event due to tripping of

evacuating lines

09-11-

2015at

09:33 hrs

Fault had occurred in 230kV MAPS-

S.P.Koil feeder-1. LBB protection got

operated as breaker of this feeder was

under lockout and resulted in tripping of

230kV bus at S.P.Koil. Unit-1&2 at

MAPS due to loss of evacuating feeders

i.e. 230kV MAPS-S.P.Koil feeder-1&2

Complete outage of 230kV Palladam,

230 kV Othakalmandapam S/s, 230 kV

Coimbatore S/s, 230 kV Thudialur and

230 kV Sadayapalayam S/s

05-09-2015

at 14:04 hrs

Disturbance in

220kV Tamilnadu

system

48/I/1

(GD)

49/I/1.5

(GD)

22-02-2016

at 12:36 hrs

51/I/3

Pending

PendingComplete outage of

220kV Nagjheri

power station and

220kV Ambewadi

substation of

KPTCL

Annexure-IV

Page 11 of 19

50/II/17

21-12-2015

at 6:28 hrs

Pending

TANTRANSCO to check the LBB scheme for LV-3, and furnish

the remedial measures taken to PCSC forum.

TANTRANSCO TANTRANSCO mail received on 24-03-2016:

CMR relay for extending LBB protection was released and LBB extended

from Distance Protection relay directly. CT is not available in the Bus

Coupler bay for zone segregation. However, during commissioning of

third ICT, Bus section Breaker will be provided for zone segregation.

Numerical BBP relay will be provided.

Mail recieved on 27-04-2016 and 20-05-2016:

CT is not available in the Bus Coupler bay for zone segregation.

However, during commissioning of third ICT, Bus section Breaker will be

provided for zone segregation. Numerical BBP relay will be provided.

Fault had occurred in 230kV Madurai-

Sembatty line. Trip from distance relay

was not extended to breaker due to

protection DC fail. LBB protection got

operated resulting in a busbar trip at

230kV Madurai substation. All

elements got tripped as there is a single

bus operation at 230kV Madurai S/s

1. TANTRANSCO to provide split-bus operation with bus

sectionalizer CB for their 230 kV Madurai (Chekanurani) SS.

2. TANTRANSCO to provide two main-zone operation for the

numerical BBP that is being commissioned.

3. TANTRANSCO to examine the feasibility of providing Re-

Trip feature for the LBB protection, and accordingly take steps

for implementing the same.

400/230kV Myvadi ICT-3 tripped due to

the operation of 230 kV CB LBB

protection at 230 KV bus (TNEB) of

Myvadi station.

27-11-2015

at 17:26 hrs

Tripping of

400/230kV Myvadi

ICT-3

Complete outage of

230kV Madurai S/s

(Chekanaurani) of

TANTRANSCO

19-01-2016

at 11:56 hrs

1. TANTRANSCO to examine the feasibility of providing two

main-zone operation for bus bar protection by exploring various

alternatives like replacing existing bus-coupler CB with a hybrid

bus-coupler CB that comes with inbuilt CT, replacing existing

BBP relay with another suitable relay that supports two main-

zone operation, and implement the same.

1. TANTRANSCO to ensure correctness of operation of LBB

relays at SP Koil.

2. TANTRANSCO & MAPS to furnish their respective

compliance report of the recommendations of to-be-conducted

PSAG-14 meeting at MAPS, Kalapakkam.

TANTRANSCOComplete outage of

S.P.Koil station of

TANTRANSCO

and generation loss

at MAPS

TANTRANSCO Mail received on 19-02-2016:

LBB scheme will be checked to ensure correctness of operation while

availing Line Clear.

TANTRANSCO and MAPS mail received on 25-01-2016:

Complaince report was submitted with respect to the recommendations

given in the Minutes of PSAG-14 Meeting.

TANTRANSCO mail received on 24-03-2016 ,27-04-2016 and 20-05-

2016:

Complaince report was submitted on 25.01.2016 with respect to the

recommendations given in the Minutes of PSAG-14 Meeting.

Busbar protection got operated for a

fault in 230kV Mywadi-Anaikadavu line

09-11-

2015at

09:33 hrs

Fault had occurred in 230kV MAPS-

S.P.Koil feeder-1. LBB protection got

operated as breaker of this feeder was

under lockout and resulted in tripping of

230kV bus at S.P.Koil. Unit-1&2 at

MAPS due to loss of evacuating feeders

i.e. 230kV MAPS-S.P.Koil feeder-1&2

49/I/1.5

(GD)

TANTRANSCO Mail received on 19-02-2016 and 24-03-2016:

Revision of Bus Bar Protection setting was carried out. The stabilizing

voltage setting was raised from 410 to 450 volts. After completing the

necessary test, the bus bar protection put in to service on 29.12.2015.

Mail recieved on 27-04-2016:

Revision of Bus Bar Protection setting was carried out. After completing

the necessary test, the bus bar protection put in to service on 29.12.2015.

TANTRANSCO

Pending

Complete outage of

230kV Mywadi

station of

TANTRANSCO

50/I/3

(GD)

51/I/1

(GD)

Pending

TANTRANSCO Mail received on 19-02-2016, 24-03-2016 and 27-04-

2016:

LBB scheme will be tested while availing Line Clear.

Mail Received on 20-05-2016:

Revision of Bus Bar Protection setting was carried out. After completing

the necessary test, the bus bar protection put in to service on 29.12.2015.

TANTRANSCO Pending

Annexure-IV

Page 12 of 19

765 kV RAICHUR -

SHOLAPUR 1 and

2

Kerala

Pending

(Recommend

ation No.1)

PGCIL (SR-I & SR-II)

Pending

(Receomme

ndation 4)

Sholapur -1 and 2 Feeder got tripped at

Raichur end on operation of over current

protection in Main-1 distance relay and

holding from Solapur end on 04.09.2015

at 19:24:42 Hrs

04-09-2015

at

19:25 hrs

Mail received on 31-07-2015:

1. Reducing the sensitivity of REF protection of Unit # 4, 5, 6 at Idukki

PH: - Generation wing is planning to purchase new transformer

management relays with low impedance REF protection. Purchase

procedures initiated. ---------Pending

2. The replacement/ repair of faulty breakers are under the consideration

of Generation wing. Breakers will be replaced / repaired in a phased

manner. Unit #3 breaker was replaced with available breaker from the

220kV IDMD feeder. The 220kV CBs of unit #2 and unit #3 will be

replaced with in two months.

3. No abnormalities were noticed in the PLCC equipment at New Pallom

station. It is kept under observation.

Mail recieved on 30-10-2015:

1. Purchase procedures is still in progress.

2. Replaced.

3. PLCC equipment Tested and found OK.

Mail recieved on 03-03-2016:

1. Even though repeated plans to have a joint inspection with M/s.ABB

who is the OEM of the relay panel for replacing the relays with numerical

ones, the same could not become successful. Finally, the inspection has

been fixed on 15.03.2016. It has been planned to replace existing REF

protection with low impedance ones after retrofitting the numerical ones

of OEM.

Mail recieved on 25-05-2016:

1.Generation wing is planning ti provide low impedance REF protection

by retrofitting numerical ABB make transformer management relay in the

existing panel. ---- Pending.

2.Faulty breaker of Unit3 has been replaced. ---- Completed.

3.PLCC equipments in the feeder were checked and found OK. ------

Completed.

KSEB1. KSEB to reduce sensitivity of REF protection appropriately at

Idukki PH.

2. KSEB to replace/ repair the faulty breaker.

3. KSEB to check the PLCC equipment at New Pallam and

inform the remedial measures taken to PCSC forum.

220 kV breaker of unit-3 at Idukki

Power

house flashed and bus differential

protection

acted. All Generators (6Nos.) along with

all

220 kV feeders tripped during the

incident.

28-04-2015

at 12:30 Hrs

1. PGCIL (SR-I) to check the A/R scheme implemented through

BCU’s at all its GIS/ SAS substations for correct

operation.

2. PGCIL (SR-I) to ensure time-synchronization of DR & EL of

765 kV Kurnool SS with GPS.

3. PGCIL (SR-I) to sort out the LEGEND ISSUE related to

tripping of the lines in the Event Logger of Raichur.

4. PGCIL (SR-I) to check & ensure the functionality &

healthiness of synchronization facility at Raichur end at

the earliest opportune time.

Pending42/II/7 Tripping of 400kV

Jeypore-Gazuwaka

line-

1&2 and tripping

of

HVDC Pole-

1&2 at Gazuwaka

23-02-2015

at

13:34 hrs

HVDC pole-1 got tripped due to failure

of 4 no. power supply card. HVDC pole-

2 tripped on DC low voltage trip.

400kV Jeypore-Gazuwaka line-1&2

tripped due to operation of Over voltage

protection at Gazuwaka end.

PGCIL (SR-I) to submit the report of M/s ABB’s on preventing

supply card failures.

PGCIL (SR-I)

PGCIL (SR-I) Mail received on 27-04-2016:

1. A/R scheme is implemented through BCUs in all the SAS stations. ----

Completed.

2. All the IEDs at 765kV Kurnool and 765kV Raichur were ynchronised

with GPS using SNTP protocol. ------- Completed.

3. The legends modified in Event/alarm list. ---------- Completed.

4. Yet to be informed. ------ Pending

Yet to be informed

Complete outage of

Idukki Hydro

Power Station (GD-

1)

44/I/1

(GD)

47/II/18

Annexure-IV

Page 13 of 19

51/II/22 Tripping of

400/220kV ICT-1

at Munirabad

18-01-2016

at 12:46 hrs

ICT-1 tripped during operation of tie

bay breaker

1. PGCIL (SR-I) to configure Event Logger (s) at Munirabad to

record event at msec level.

2. PGCIL (SR-I) to set right Time and Field Time values being

shown in EL to proper values.

PGCIL (SR-I) Mail received on 27-04-2016:

Noted and shall be followed

Pending

52/II/6 Tripping of ICT-2

at Cudappah

substation

25-02-2016

at 14:23 hrs

ICT-2 tripped on operation of

directional over current. At the same

time B-phase to earth fault had occurred

in 400 kV Cuddapah-Kolar line

PGCIL (SR-I) to revise settings for high-set unit of ICT’s back-up

protection at their Kadapa SS such that it will not operate for a

through fault that has been cleared in time.

PGCIL (SR-I) Mail received on 27-04-2016:

Relay settings were as per our corporate recommendations and are same

for all the ICTs in the region. However, suggestion of PCSC is being

taken up with our CC/Engineering.

Pending

41/II/12 Tripping of 400KV

Coastal-NTPL line

13-02-2015

at 22:54 hrs

Line tripped B-phase to earth fault and

later tripped on R-Y phase fault. From

Coastal end D.R, Y & B poles of

breaker opened first and R-pole appears

to be opened on Pole discrepancy.

CEPL to check A/R scheme at their end. CEPL Yet to be informed Pending

44/III/4 Tripping of 400kV

Coastal (CEPL)-

Tuticorin pooling

station

20-04-2015

at 12:35 hrs

Line tripped at Coastal energen end only

and was holding from TTRNPS

CEPL to furnish a detailed report on this trip event to PCSC

forum.

CEPL Yet to be informed Pending

47/III/2 Tripping of 400kV

Vemagiri – GVK

(JPD)

line-2

16-07-2015

at 17:02 hrs

R-phase to earth fault had occurred in

line. Line auto reclosed at Vemagiri end

and failed to reclose at GVK end.

GVK to put A/R into service at GVK Jegurupadu end on 400 kV

GVK (Jegurupadu) – Vemagiri line-2.

GVK (Jegurupadu) Yet to be informed Pending

Kurnool -II Feeder got tripped on B-N

fault and holding from Kurnool end

(successfully auto-reclosed at Kurnool

end) subsequently

tripped at other end on operation of

Over Voltage, Stage-I protection at

Raichur end on 04.09.2015 at 19:24 Hrs

04-09-2015

at

19:25 hrs

765 KV RAICHUR

–

KURNOOL 2

Others

Pending

(Receomme

ndation 4)

1. PGCIL (SR-I) to check the A/R scheme implemented through

BCU’s at all its GIS/ SAS substations for correct

operation.

2. PGCIL (SR-I) to ensure time-synchronization of DR & EL of

765 kV Kurnool SS with GPS.

3. PGCIL (SR-I) to sort out the LEGEND ISSUE related to

tripping of the lines in the Event Logger of Raichur.

4. PGCIL (SR-I) to check & ensure the functionality &

healthiness of synchronization facility at Raichur end at

the earliest opportune time.

PGCIL (SR-I) Mail received on 27-04-2016:

1. A/R scheme is implemented through BCUs in all the SAS stations. ----

Completed.

2. All the IEDs at 765kV Kurnool and 765kV Raichur were ynchronised

with GPS using SNTP protocol. ------- Completed.

3. The legends modified in Event/alarm list. ---------- Completed.

4. Yet to be informed. ------ Pending

TANTRANSCO mail received on 24-03-2016:

3Ф Trip at 400kV Alamathy end due to DT received from vallur end for

BФ LAS bursted in Alamathy -Thiruvalam - 1 # at Alamathy end.

Mail received on 27-04-2016 and 20-05-2016:

3Ф Trip at 400kV Alamathy end due to DT received from vallur end for

BФ LAS bursted in Alamathy -Thiruvalam - Line-1 at Alamathy end.

PendingNTECLNTECL, Vallur to furnish a report detailing the reasons for mal-

operation of Vallur end relays for a fault on Alamathy-Tiruvalam

line-1, and remedial measures taken to PCSC forum. In the report,

their preparedness for implementing line differential protection on

Vallur-Alamathy lines may also be indicated.

47/II/18

400kV Vallur-Alamathy Line-2 got

tripped from Vallur end during failure of

Y-phase LA in 400kV Alamathy-

Tiruvalam line. Protection at Vallur end

tried for an auto-reclose and gave a 3

phase trip.

13-12-2015

at 22:42 hrs

Tripping of 400kV

Alamathy-

Tiruvalam line-1

and 400kV

Alamathy-Vallur

line-2

51/II/4

Annexure-IV

Page 14 of 19

51/II/7 Tripping of 400 kV

Vemagiri-

Gauthami-2

26-12-2015

at 00:01 hrs

Line tripped on operation of over

voltage protection at Gauthami end and

direct trip was received at Vemagiri.

FIR, DR and EL of Gouthami end was

not available to validate the over voltage

tripping.

1. GVK Gautami to adjust drop-off to pick-up ratio to > 98% for

the Over Voltage relays at Gautami end on 400 kV Gautami –

Vemagiri lines.

2. GVK Gautami to ensure time-sync of all DR’s & EL’s at

Gautami Station with GPS

GVK (Gautami) Yet to be informed Pending

52/IV/3 Tripping of 400kV

Vemagiri-GMR

line-2

09-02-2016

at 12:57 hrs

Tripped at GMR end only and line is in

service from Vemagiri.

GMR to furnish a detailed report on the tripping event along with

remedial measures taken to PCSC forum.

GMR Yet to be informed Pending

53/I/6 Complete outage of

NTPL and CEPL

power Station

17-04-2016

at 01:09 hrs

Running Units got tripped due to

tripping of 400kV Coastal-Tuticorin PS

line and 400kV NTPL-Tuticorin PS

line. 

CEPL to modify and put in place with immediate effect the

existing SPS at their Station such that it operates even for single-

pole opening on CEPL – TTNPS line due to A/R operation [in

addition to its (SPS’s) operation on 3-pole opening that results

from permanent faults] on account of single-ph-ground faults.

CEPL Yet to be informed Pending

53/III/11 Tripping of 400kV

Ramagundam-

Chandrapur line-1

27-03-2016

at 22:06 hrs

Line tripped on Y- phase to earth fault.

Line did not auto-reclose.

NTPC – Ramagundam to provide Auto-reclose feature for Tie-

CB’s also In addition to the Main-CB’s.

NTPC Yet to be informed Pending

Miscellaneous

On account of R-phase to earth fault,

line tripped at Hassan end due to

operation of distance Zone-2 and non-

receipt of carrier. From D.R of

Talaguppa end it is observed that fault

had occurred in Yphase.

01-01-2015

at

13:38 hrs

Tripping of 400

kV TALAGUPPA

– HASSAN line

40/II/3

PendingKPTCL/

PGCIL (SR-I)

1. PGCIL and KPTCL to ascertain the reason for the phase

discrepancy in the relay operation and take suitable remedial

measures.

2. KPTCL to check the PLCC operation at Talaguppa end and

submit the report to the PCSC forum.

PGCIL (SR-II)/

KPTCL

As reported directional over current

relay of ICT’s operated due to

snapping of line jumper in 220kV

Lingapur line.

16-07-2014400/220 kV ICT-1

& 2 at

MUNIRABAD

34/I/6 Mail recieved on 27-05-2015 (KPTCL):

1. KPTCL has taken action to provide bus bar protection to 220kV buses.

2. Over current relay Settings of ICTs to be reviewed by PGCIL.

Mail received on 29-07-2015 (KPTCL):

Initial Tendering stage

KPTCL Mail recieved on 23-01-2016:

Detailed estimate prepared for taking up the work. CEE, Transmission

Zone, Gulbarga will take up necessary procurement and further

execution.

1. Bus bar protection shall be provided by asset owner ( i.e

KPTCL).

2. Settings for main distance protection & Overcurrent

protection shall be examined and reviewed.

3. Time synchronization of the Substation shall be ensured.

4. Correct DR shall be submitted to the SRLDC for trip analysis.

Mail recieved on 28-04-2015:

End to end testing of PLCC has been done and problem in the PLCC is

atttended.

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

End to end testing of PLCC has been done and problem in the PLCC is

atttended. Phase discrepancy in the relay operation is to be checked

jointly.

Mail recieved on 02-09-2015 from PGCIL (SR-II):

Problem is in identification of phases at Talguppa end. To be rectified by

M/s KPTCL.

Pending

(with

KPTCL)

Annexure-IV

Page 15 of 19

43/II/12 Multiple tripping at

400kV Raichur

(PG) and Raichur

TPS of KPCL

11-04-2015

at 18:04 hrs

400kV Raichur(PG) - Gooty line-2,

400kV RTPS - Raichur (PG) lines-1&2,

400kV RTPS - Mahboobnagar, Unit#5

at RTPS tripped during the incident

KPCL, KPTCL and PGCIL (SR-I) to furnish the action taken

report on the recommendations given by PSAG-13 that held its

meeting at Raichur on 22-04-2015 and 23-04-2015.

KPCL/KPTCL/

PGCIL(SR-I)

Yet to be informed by PGCIL (SR-I). Pending

[with PGCIL

(SR-I)]

Tripping of Unit 1

at NCTPS

24-05-2015

at 19:13 hrs

ID Fan trip

Tripping of Unit 1

at MEPL

24-05-2015

at 19:13 hrs

Coal Mill tripped

Tripping of Unit 1

at

Krishnapatnam

24-05-2015

at 19:17 hrs

Generator Protection operated

Tripping of Unit-8

at RTPS

24-05-2015

at 19:19 hrs

Tripped on Overvoltage.

Pending

(with

APTRANSC

O)

400kV Raichur TPS-Raichur(PG) line-

1&2, 400kV Raichur-Mahboobnagar,

Unit#7 and ICT-2 at RTPS tripped

during the incident. B phase to earth

fault had occurred in 400kV Raichur

TPS-Raichur line-1

09-03-2015

at

06:36 hrs

Multiple tripping at

Raichur TPS of

KPCL

42/II/18

1. PGCIL (SR-I) to enable Auto reclosure feature at Vijayawada

end.

2. PGCIL (SR-I) to check distance relay settings for Vijayawada –

Vemagiri line-3, and furnish a compliance report to PCSC forum.

400kV Vemagiri-Vijayawada lines -

1&3, 400kV Vemagiri-Gautami line-2,

400kV Vemagiri-Konaseema line-2 and

400/220kV ICT-2 at Vemagiri tripped

during the incident. Triggering incident

was failure of B-phase L.A in 400kV

Vijayawada-Vemagiri line-1 at Vemagiri

end.

25-04-2015

at 10:04

hrs

Multiple tripping at

Vemagiri

substation of

APTRANSCO

44/II/6

1. Yet to be informed by KPCL.

2. Mail received on 26-05-2015 from TSTRANSCO:

It is found that the main-2 ABB make REL316 type distance relay was

defective and same was replaced with MICOM P444 by M/s.PGCIL on

23.04-2015. After replacement of main-II, DR can be extracted from this

relay. For EL in to service, some field winding is pending which is being

taken up in this month.

3. PGCIL mail recieved on 27-04-2016:

End to end PLCC tunning carried out

1. KPCL to review REF setting (DMT or IDMTL) for unit-7 by

first week of April, 2015 and inform the same to PCSC forum.

2. TSTRANSCO to furnish Mehaboobnagar’s DR and EL and the

reasons for distance relay operation at their end within a week’s

time.

3. PGCIL (SR-I) to rectify the issues relating to A/R operation,

relay reach (Z2), reverse reach (Z4) and SOTF auxiliary contacts

within a week’s time, and submit the actions taken to PCSC

forum.

KPCL/

TSTRANSCO/

PGCIL (SR-I)

Pending

(with KPCL)

PGCIL/

APTRANSCO

PGCIL Mail received on 27-04-2016:

1. For Vijayawada - Vemagiri - 3 feeder A/R at Vijayawada end is in

service and relay settings were revised and implemented as per

Ramakrishna committee recommendations.

2. For Vijayawada - Vemagiri - 1 feeder (Asset belongs to

APTRANSCO), A/R relay is not envisaged. APTRANSCO has to

carryout the wiring/programming in Main-1 protection OR to provide

seperate A/R Relay.

44/I/3 1. All Tripped units, viz., Krishnapatinam, MEPL, Raichur,

NCTPS to submit a detailed report on this event including the

remedial measures taken to PCSC forum.

2. KPCL to check the excitation system of Unit 8 of RTPS, and

submit the remedial measures taken to PCSC forum.

KPCL/ MEPL/

APGENCO/ TNEB

TANGEDCO vide their mail dated 07.07.2015 informed that as per the

discussion and recommendation of 44th meeting of PCSC held on

28.05.2015, a time delay of 2 Sec had been introduced for the above

tripping for all the ID fans at NCTPS-II.

MEPL vide their mail dated 14.09.2015 informed that they had

implemented 2 seconds delay for under voltage tripping of all Drag Chain

Feeder Conveyors. And this has been done for both the Units.

Pending

(with KPCL,

APGENCO)

Annexure-IV

Page 16 of 19

1. APGENCO to furnish to PCSC forum (i) A3-size Single Line

Diagram of SDSTPS, and (ii) the sequence of events with time

stamp showing the protection that opened Tie-CB (405) at

SDSTPS.

2. APGENCO to review STUB/TEED protection in all dias at

SDSTPS and ensure that they are configured for instantaneous

operation.

3. APGENCO to properly configure the STATE of the tripping

events so that they get recorded appropriately like TRIP/

OPERATED in their corresponding Event Loggers.

4. APGENCO to ensure time sync of all DR’s and EL’s at

SDSTPS.

5. PGCIL (SR-I) to provide line differential protection for 400 kV

NPS –Nellore-PG lines 1 & 2.

As per FIR submitted, CT damage

observed in Chitoor-Main bay (404).

Main breakers connected to bus-1 (401,

404, 407, 410) got tripped on operation

of bus bar protection. Unit-1 tripped on

operation of MFT. Unit-2 was not in

service

08-09-2015

at 18:20 hrs

Complete outage of

Krishnapatnam

TPS

47/I/2 APGENCO/ PGCIL

(SR-I)

Mail received on 27-04-2016 from PGCIL (SR-I):

Procurement of differential protection for 400kV NPS-NLR D/C and

400kV RCR-RTPS-D/C is under tendering.

Pending

1. MEPL to ensure healthiness of all CT’s by carrying out Tan

Delta and DGA tests wherever necessary.

2. MEPL to take suitable action to correct the operation of tie-

CB Bay Control Unit that caused LBB/ BBP operation.

3. PGCIL (SR-1) to carry out end-to-end PLCC testing in

coordination with MEPL and ensure that carrier-aided protection

on MEPL – NPS line is in healthy condition.

4. SEL to properly time-coordinate their Over Current phase and

Earth fault relays in consultation with MEPL.

MEPL/ PGCIL (SR-

I)/ SEL

MEPL vide their mail dated 14.09.2015: informed the following

1. Tan Delta Testing of winding and DGA of Insulating Oil for all CTs

was carried out and found to be normal.

2. Could not find any problem during internal checks hence we are in

touch with ABB for rectification work. Will be done by the end of 15th

Oct'15.

3. End to end testing of Carrier signals was carried out and found them

healthy.

Pending

(with MEPL

& SEL)

Y phase CT failure at MEPL led to

tripping of 400kV NPS-MEPL, 400kV

SEPL-MEPL line and Unit-2 at MEPL.

Uni-1 was not in service at the time of

tripping

20-05-2015

at 20:38 hrs

Complete outage of

MEPL power

station

45/I/2

R-phase to earth fault had occurred in

400kV Coastal NTPL line. Line auto-

reclosed at NTPL end and failed to

reclose at Coatal end. Auto reclose

block was persisting due to PLCC

channel fail. Also running Units-1&2 at

NTPL tripped on operation of GT

differential protection.

03-08-2015

at

15:43 hrs

Tripping of 400kV

Coastal-

NTPL line and

running units

at NTPL

47/II/9 1. NTPL to ensure (i) proper DATE settings, and (ii) time-sync

with GPS for DR and EL at NTPL.

2. CEPL to furnish remedial measures taken regarding PLCC

channel failure.

NTPL/ CEPL Yet to be informed Pending

Mail recieved on 25-05-2016 from KPTCL:

Availability of week end infeed with eco feature to be confirmed by

SEE,RTC,Hubli

PendingKPTCL/ KPCL/

NPCIL (KAPS)

1. KPTCL/ KPCL to see the possibility of implementing Weak

Infeed logic with Echo feature enabled by Under

Voltage (27) element on Kadra-Karwar lines 1 &2, and

implement the same if feasible.

2. NPCIL to time-coordinate Kaiga’s DEFR settings with (i) Zone-

2 settings at Kaiga, and (ii) primary protections of the lines

emanating from Kadra and Kodasalli.

3. KPCL to ensure time-sync of EL’s, and healthiness of the Fault

Locators at Kadra.

220kV Kadra-Karwar lines-1&2 tripped

on earth fault in B-phase in zone-2.

Kaiga-Kadra line tripped at Kaiga end

only on operation of directional eath

fault protection.

31-07-2015

at

11:44 hrs

Tripping of 220kV

Kadra-Karwar lines

- 1&2 and 220kV

Kaiga-Kadra line

47/II/7

Annexure-IV

Page 17 of 19

50/II/11 Tripping of 400kV

Neyveli TS2-

Pugalur line

14-11-2015

at 4:01 hrs

Line tripped on operation of over

voltage protection at Pugalur end.

However from DR it was observed that

the voltages were below the O/v stg-1

threshold limits

1. NLC to configure DT receipt event from Pugalur for triggering

DR and EL at NLC TPS II.

2. PGCIL (SR-II) to check drop-off to pick-up ratio of OVR relay

at Pugalur and configure its operation as per SRPC provided OVR

gradings.

PGCIL (SR-II)/

NLC

NLC mail received on 25-03-2016 and 27-04-2016:

Recommended configuration of DR/EL will be done during shut down of

feeder

Pending

51/II/6 Tripping of 400kV

Sattenapalli-

Vijayawada line

25-12-2015

at 3:01 hrs

Line tripped due to operation of over

voltage protection at Vijayawada end

and Direct Trip was received at

Sattenapalli end

1. PGCIL (SR-I), in co-ordination with APTRANSCO, to address

the problem with CB at the earliest opportune time.

2. APTRANSCO to take steps to replace the faulty Event Logger

at Vijayawada (Nunna) SS.

PGCIL (SR-I)/

APTRANSCO

PGCIL mail received on 27-04-2016:

Being pursued with APTRANSCO

Pending

TSGENCO mail received on 24-02-2016:

1. TSGENCO in coordination with APTRANSCO, PLCC end to end

testing completed for Srisailam- Kurnool S/C line and DT Send/ Receive

& Carrier Send/ Receive Signals are found normal. ---- Completed.

2. Auto- reclose was disabled at Srisailam end for SSLM- KNL feeder

(As per the settings given by Systems Protection/ TSTRANSCO). The

feeder contains XLPE cable & GIS. ----------- Completed.

3. TSGENCO intimated to M/s ABB India Ltd. Service Engineer will

come and resolve the configuration problems. ---- Pending

APTRANSCO mail received on 24-02-2016:

1. In coordination with the TSGENCO end to end PLCC Channels and

carrier aided protection schemes testing was carried out and found

satisfactory. ---------- Completed.

1.TSGENCO in coordination with APTRANSCO to carry out end-

to-end testing of PLCC channels by 15.12.2015 on 400 kV

Srisailam – Kurnool S/C line and 400 kV Srisailam – Sattenapalli

D/C line.

2. TSGENCO and APTRANSCO to make A/R functional on 400

kV Srisailam – Kurnool line.

3. TSGENCO to resolve configuration problems with the newly

commissioned relays at Srisailam LB so that unwarranted DT

sending to remote ends is addressed.

TSGENCO/

APTRANSCO

400kV Kurnool-Srisailam line - distance

protection zone-2 had operated at

Srisailam end. However from DR, R-

phase to earth fault and zone-2 start

were observed. Breakers at Kurnool end

tripped on direct trip receive from

Srisailam end.

ICT-2 Main-CB tripped due to

operation of bus bar protection, and Tie-

CB tripped due to DT receipt from

Srisailam

26-10-2015

at 14:31 hrs

Tripping of

400/220 kV ICT-2

at Kurnool

Substation and

400kV Kurnool-

Srisailam line

49/II/11 Pending

(with

TSGENCO)

Pending

1. For Gooty –Nelamangala line, PGCIL (SR-I) and KPTCL to

provide 3-ph trip logic at their respective ends upon detection of

PLCC link failure during dead-time of A/R operation.

2. PGCIL (SR-I) to make GPS functional at Gooty SS, and

ensure time-sync of various DR’s and EL’s with it (GPS).

3. PGCIL (SR-I) /KPTCL to furnish reason for the operation of

Backup impedance protection of the line reactor at Nelamangala

end and the remedial measures taken to PCSC forum.

PGCIL (SR-I) /

KPTCL

PGCIL Mail received on 27-04-2016:

1. A/R blocked due to failure of PLCC link. The defective PLCCcards

replaced at Neelamgala end. ------ Pending

2. Gooty end Time syc unit is replaced with new one and commissioned. --

------ Completed.

3. Yet to be informed.

PendingR-phase to earth fault had occurred in

Line. Line did not auto-reclose from

both ends. It was mentioned that Y&B

pole breakers at Neelamangala tripped

on operation of pole discrepancy and

backup impedence protection for line

reactor got operated.

12-11-2015

at 00:20 hrs

Tripping of 400kV

Gooty-

Nelamangala line

50/II/8

Running units at Thermal Powertech

power Station tripped due to tripping of

400kV Nellore pooling station (NPS)-

TPCIL line and 400kV Nellore pooling

station (NPS)-ECC line

30-12-2015

at 06:02hrs

Complete outage of

TPCIL power

station

50/I/2 1.PGCIL (SR-I) to furnish Action Taken Report on the findings

of OEM on relay mal-operation at NPS end on 400 kV NPS –

NCCK line to PCSC forum.

2. PGCIL (SR-I) to appropriately configure Station Event Logger

at NPS to record events at msec interval.

3. PGCIL (SR-I) to carry out PLCC end-to-end testing in

coordination with TPCIL for 400 kV NPS –TPCIL line.

4.PGCIL (SR-I), MEPL, SEL, TPCIL & NCC to take steps to

provide line differential protection at their respective ends on all

400 kV lines (except Gooty line) emanating from Nellore Pooling

Station, and furnish an action plan to implement the same.

PGCIL (SR-I),

MEPL, SEL, TPCIL,

NCC

PGCIL (SR-I) mail received on 27-04-2016:

1. The firmware of REL670 is being upgraded. ------- Completed.

2. The recording of events in msec interval is being taken up with OEM.

Henceforth, for analysis purpose, we will provide larm list which has

msec time stamp. -------- Completed.

3. End to end testing of PLCC code transmision and tuning of channels

carried out. ------- Completed.

4. Procurement of differential protection for 400kV NPS-NLR D/C and

400kV RCR-RTPS-D/C is under tendering. The legends modified in

Event/alarm list. Provision of diff. rel;ay for all short lines emanating

from NPS is being taken up with our corporate. -------- Pending.

Annexure-IV

Page 18 of 19

52/I/8 Complete outage of

400kV NTPL

station and CEPL

Stations

14-03-2016

at 01:36 hrs

Running Units at NTPL and Coastal

Energen power station got tripped due to

tripping of evacuating lines.

NTPL and PGCIL (SR-II) to furnish compliance report of the

recommendations given by PSAG-15 Committee that held its

meeting on 12-13 April, 2016 at NTPL, Tuticorin.

PGCIL (SR-II)/

NTPL

NTPL mail received on 19.05.2016:

All General Recommendations will be done in the second week of June

2016 ---------- Complied by NTPL.

Yet to be informed by PGCIL (SR-II)

Pending

[with PGCIL

(SR-II)]

1. KPTCL to configure the Auto-Reclosure (A/R) scheme at

Hoody end for all lines emanating from Hoody end in such a way

that in the event of occurrence of faults during A/R dead-time, (i)

it should immediately give a 3-ph trip, and (ii) A/R should go into

lock-out state, i.e., it must not reclose after the elapse of dead-

time of A/R.

2. As regards over-reaching of Kolar and Nelamangala end

relays for the fault on 400 kV Hoody – Kolar line-2, KPTCL and

PGCIL (SR-II) are recommended to modify the Z1B settings of

the relays used (7SA522) suitably so that they operate with a

Zone-2 time delay.

3. KPTCL to check the ICT’s back-up (high-set) protection

settings, and ensure that they operate with a time delay of 100

msec.

4. KPTCL to take steps to replace the solid state relays at

Hoody end on Hoody-Nelamangala lines – 1 & 2 with numerical

relays at the earliest.

KPTCL/

PGCIL (SR-II)

KPTCL Mail recieved dated 25-05-2016:

1. Incorporated. --- Completed.

2. Yet to be informed.

3. With the existing electromechanical relays, it's not possible to add time

delay of 100 mSec. However, ongoing R&M works of Hoody included

complete ICT1 and ICT2 panel replacement having Numerical relays.

4.The solid state relays of Nelamangala-1 and Nelamangala-2 lines will

be replaced by numerical relays for which relays have been

identified,Will be attended in a month's time.

Pending400kV Hoody-Nelamangala line-1&2,

400kV Hoody-Kolar line-1&2,

400/220kV ICT-2 at Hoody tripped

during the incident. ICT-1&3 were hand

tripped after the incident.

26-03-2016

at 12:42 hrs

Complete outage of

400kV Hoody

substation of

KPTCL

53/I/5

Annexure-IV

Page 19 of 19

Sl.No. Element NameOutage

date/time

Revival

date/time

Reason for

OutageSender/ Receiver

Remedial Measures/ Actions

taken

1 220 kV SEDAM - TANDUR29-02-

2016/18:14:00

29-02-

2016/22:23:00

DISTANCE

PROTECTION

OPERATED

KPTCL/ TSTRANSCO

KPTCL: As per the information

received from Tandoor Sub

station, bus fault had occurred at

Tandoor Sub station during the

instance.

2 220 kV SABARGIRI - THENI12-03-

2016/13:55:00

12-03-

2016/14:35:00R-N FAULT KSEB/ TANTRANSCO

TANTRANSCO: Temporary fault.

AR lockout at Theni end. Feeder

normalised at 14:35 hrs.

KSEB:

3 400 Kv KAYATHAR - KARAIKUDI 101-04-

2016/12:49:00

02-04-

2016/13:31:00

TRIPPED ON B-PH

FAULTTANTRANSCO / PGCIL (SR-II)

TANTRANSCO: Temporary fault.

AR closed & lockout. Line patrol

was carried out and no visible

fault found.

PGCIL-SR2:

4 400 Kv KAYATHAR - KARAIKUDI 107-04-

2016/12:50:00

07-04-

2016/14:09:00

TRIPPED REASON

AWAITEDTANTRANSCO / PGCIL (SR-II)

TANTRANSCO: Temporary fault.

AR closed & lockout.

5 400 Kv NCTPS - VALLUR 107-04-

2016/18:48:00

08-04-

2016/08:05:00

HEAVY TRACKING

@ VLR ENDTANGEDCO / NTECL

TANTRANSCO/TANGEDCO:

Feeder hand tripped from Vallur

end and Direct Trip received at

NCTPS-II end.

Pending Remedial Measures/ Actions taken

for the Critical Tripping Incidents (as on 10.06.2016)

Annexure-V

Page 1 of 11

6 400 Kv NCTPS - VALLUR 207-04-

2016/19:42:00

08-04-

2016/07:59:00

HEAVY TRACKING

@ VLR ENDTANGEDCO / NTECL

TANTRANSCO/TANGEDCO:

Feeder hand tripped from Vallur

end and Direct Trip received at

NCTPS-II end.

7 400 Kv NCTPS - VALLUR 213-04-

2016/18:52:00

07-05-

2016/13:26:00

TRIPPED ON R-PH

FAULTTANGEDCO / NTECL

TANTRANSCO/TANGEDCO: R-

phase Insulator at location no.12,

R,Y&B insulators at location no.13

and Gantry R,Y&B insulators were

replaced

8 220 kV EDAMON - TIRUNELVELI 214-04-

2016/16:54:00

14-04-

2016/17:07:00

TRIPPED ON R-PH

FAULTKSEB / PGCIL (SR-II)

PGCIL(SR-II):Tripped on R-N fault

due to lightning.

9 220 kV SEDAM - TANDUR15-04-

2016/15:46:00

15-04-

2016/17:06:00

BUSBAR PROT.

OPERATED @

220KV RCR END

KPTCL / TSTRANSCO To-be-discussed

10 400 kV HASSAN - NEELAMANGALA16-04-

2016/00:19:00R-Y FAULT PGCIL (SR-II) / KPTCL

PGCIL(SR-II):Tripped on R-Y fault

due to lightning.

11 400 kV DICHIPALLY - RAMAGUNDAM16-04-

2016/11:21:00

16-04-

2016/12:00:00

TRIPPED ON R-PH

FAULTTSTRANSCO / NTPC To-be-discussed

12 400 kV DICHIPALLY - RAMAGUNDAM16-04-

2016/13:51:00

16-04-

2016/14:35:00B - N FAULT TSTRANSCO / NTPC To-be-discussed

13 400 Kv KAYATHAR - KARAIKUDI 217-04-

2016/14:37:00

17-04-

2016/15:18:00R-N FAULT TANTRANSCO / PGCIL (SR-II)

TANTRANSCO: Temporary fault

and AR lockout at both ends.

14 400 Kv COASTAL - TTRNPS17-04-

2016/02:52:00

H/T DUE TO TO

AVOID MULTIPLE

A/R OPERATIONS(

NO GEN UNITS

AVAILABLE)

CEPL / PGCIL (SR-II)

PGCIL(SR-II):H/T as per the CEPL

request due to flash over of

insulators at CEPL end vide SRLDC

code CR-04/385

15400 kV MAHABOOB NAGAR -

RAICHUR

19-04-

2016/21:42:00

19-04-

2016/22:20:00

MALOPERATION

OF RELAY @ RCR

END

TSTRANSCO / KPTCL To-be-discussed

Annexure-V

Page 2 of 11

16 400 Kv VTPS - MALKARAM 122-04-

2016/13:29:00

22-04-

2016/16:18:00R PH FAULT APGENCO / TSTRANSCO To-be-discussed

17 400 kV GUTTUR - HIRIYUR 222-04-

2016/03:04:00CVT FAILURE KPTCL / PGCIL (SR-II)

PGCIL(SR-II):Emergency S/D

availed for replacing failed CVT at

HYR end vide SRLDC code CR-

04/546.

18 400 kV RAMAGUNDAM - GAJWEL23-04-

2016/10:09:00

23-04-

2016/13:16:00

TRIPPED ON B-PH

FAULTNTPC / TSTRANSCO To-be-discussed

19 400 kV HASSAN - NEELAMANGALA23-04-

2016/17:48:00

Y- PH LA BLAST @

NLM ENDPGCIL (SR-II) / KPTCL To-be-discussed

20 400 Kv KLVDPT - VALLUR 224-04-

2016/13:52:00

24-04-

2016/14:21:00R - N FAULT PGCIL (SR-II) / NTECL

PGCIL(SR-II):Tripped on R-N

transient earth fault.

21 400 Kv VTPS - MALKARAM 124-04-

2016/14:12:00R -N FAULT APGENCO / TSTRANSCO To-be-discussed

22 220 kV AMBEWADI - PONDA 125-04-

2016/00:06:00DEFR OPERATED KPTCL / GOA To-be-discussed

23 400 kV KHAMMAM - N'SAGAR 126-04-

2016/09:25:00

26-04-

2016/10:06:00R-N FAULT PGCIL (SR-I) To-be-discussed

24 400 Kv HASSAN - UPCL 126-04-

2016/14:05:00

26-04-

2016/17:00:00R-N FAULT KPTCL / UPCL

KPTCL:At 15.28Hrs, 400kV Hassan-

UPCL-1 was under open condition

due to fault. Tripping of Hassan-

UPCL-2 resulted in SPS operation

and uniit2 generating around 600

MW tripped during the instance.

Annexure-V

Page 3 of 11

25 400 Kv HASSAN - UPCL 226-04-

2016/15:28:00R-Y FAULT KPTCL / UPCL

KPTCL:At 15.28Hrs, 400kV Hassan-

UPCL-1 was under open condition

due to fault. Tripping of Hassan-

UPCL-2 resulted in SPS operation

and uniit2 generating around 600

MW tripped during the instance.

26 400 kV SIMHADRI - KALPAKKA 430-04-

2016/04:15:00DUE TO BUS FAULT NTPC/APTRANSCO To-be-discussed

27 400 kV KALPAKKA - VEMAGIRI 230-04-

2016/04:15:00DUE TO BUS FAULT APTRANSCO To-be-discussed

28 400 Kv NCTPS - VALLUR 130-04-

2016/17:09:00

TRIPPED ON R-PH

FAULTTANGEDCO/ NTECL

TANTRANSCO/TANGEDCO: Line

patrolling work completed and at

Loc. No. 10, R-Ph. insulator Decap.

Defect attending work under

progress.

29 400/220 kV ICT-1 AT RAICHUR01-05-

2016/21:45:00

B/B-1 PROTECTION

OPERATED DUE TO

ICT-1 CT

FLASHOVER

KPCL To-be-discussed

30400 kV N'SAGAR - MAHABOOB

NAGAR

01-05-

2016/21:45:00

B/B-1 PROTECTION

OPERATED DUE TO

ICT-1 CT

FLASHOVER

PGCIL (SR-I)/TSTRANSCO To-be-discussed

Annexure-V

Page 4 of 11

31 400/220 kV ICT-3 AT RAICHUR01-05-

2016/21:45:00

01-05-

2016/23:05:00

B/B-1 PROTECTION

OPERATED DUE TO

ICT-1 CT

FLASHOVER

KPCL To-be-discussed

32 400 Kv RAICHUR - YTPS01-05-

2016/21:45:00

01-05-

2016/22:24:00

B/B-1 PROTECTION

OPERATED DUE TO

ICT-1 CT

FLASHOVER

KPCL To-be-discussed

33400 kV MAHABOOB NAGAR -

RAICHUR

01-05-

2016/21:45:00

01-05-

2016/23:25:00

B/B-1 PROTECTION

OPERATED DUE TO

ICT-1 CT

FLASHOVER

TSTRANSCO/KPCL To-be-discussed

34 400 Kv KUDAMKULAM - MADURAI02-05-

2016/22:15:00

02-05-

2016/22:37:00R-N FAULT NPCIL/PGCIL (SR-II)

PGCIL(SR-II):Tripped on transient

earth fault in the line, persisting

beyond the dead time.

NPCIL: A/R scheme for other 3

lines i.e KKNPP to Tirunelvelli are

implemented &Kept in

service.A/R implementation of

A/R Scheme for KKNPP to

Madurai line will be enabled after

getting clearance from NPCIL HQ

Design group.

35 400 kV VIJAYAWADA - KHAMMAM02-05-

2016/15:51:00

02-05-

2016/16:01:00Y - N FAULT PGCIL (SR-I) To-be-discussed

Annexure-V

Page 5 of 11

36 220 kV AMBEWADI - PONDA 102-05-

2016/04:53:00

TRIPPED AT

AMEBEWADI END

PNLY

KPTCL/ GOA To-be-discussed

37 400 kV JEYPORE - GAZUWAKA 203-05-

2016/22:39:00INTERZONE FAULT PGCIL (ER-I)/ PGCIL (SR-I) To-be-discussed

38 400 kV KALPAKKA - GAZUWAKA 103-05-

2016/22:37:00

TRIPPED ON R-PH

FAULTAPTRANSCO/ PGCIL (SR-I) To-be-discussed

39 220 kV AMBEWADI - PONDA 103-05-

2016/13:03:00

03-05-

2016/21:30:00

PHASE TO PHASE

FAULTKPTCL/ GOA To-be-discussed

40400 kV RAMAGUNDAM -

HYDERABAD 3

03-05-

2016/16:27:00

03-05-

2016/20:08:00PH-PH FAULT NTPC/ PGCIL (SR-I) To-be-discussed

41400 kV RAMAGUNDAM -

CHANDRAPUR 1

04-05-

2016/19:16:00

04-05-

2016/20:21:00B-N FAULT NTPC/PGCIL (WR-I) To-be-discussed

42 HVDC BHADRAVATHI POLE 104-05-

2016/19:27:00

05-05-

2016/04:40:00TRIPPING OF LINES PGCIL (WR-I) To-be-discussed

43 HVDC BHADRAVATHI POLE 204-05-

2016/19:27:00

05-05-

2016/03:39:00TRIPPING OF LINES PGCIL (WR-I) To-be-discussed

44 400 Kv BTPS - YTPS04-05-

2016/17:16:00

04-05-

2016/18:12:00R-N FAULT KPCL To-be-discussed

45 400 Kv SATTENAPALLI - SRISAILAM 104-05-

2016/21:47:00

TRIPPED ON R-PH

FAULTAPTRANSCO/ TSGENCO To-be-discussed

46 400 kV GOOTY - NELAMANGALA04-05-

2016/15:22:00

04-05-

2016/15:49:00R-N FAULT PGCIL (SR-I)/ KPTCL To-be-discussed

47 400 kV KAIGA - GUTTUR 108-05-

2016/14:10:00

08-05-

2016/14:45:00

TRIPPED ON B-PH

FAULTNPCIL/ KPTCL

PGCIL(SR-II):Portion of the line in

which fault occurred owned and

maintained by M/s KPTCL. May be

clarified from M/s KPTCL

Annexure-V

Page 6 of 11

48 400 Kv KUDAMKULAM - MADURAI08-05-

2016/17:32:00

08-05-

2016/17:46:00

TRIPPED ON R-PH

FAULTNPCIL/ PGCIL (SR-II)

PGCIL(SR-II):Tripped at KKUM end

only due to non-implementation

of A/R scheme at KKUM end.

NPCIL: A/R scheme for other 3

lines i.e KKNPP to Tirunelvelli are

implemented &Kept in

service.A/R implementation of

A/R Scheme for KKNPP to

Madurai line will be enabled after

getting clearance from NPCIL HQ

Design group.

49 400 Kv KUDAMKULAM - MADURAI08-05-

2016/20:25:00

08-05-

2016/20:35:00

TRIPPED ON R-PH

FAULTNPCIL/ PGCIL (SR-II)

PGCIL(SR-II):Tripped at KKUM end

only due to non-implementation

of A/R scheme at KKUM end.

NPCIL: A/R scheme for other 3

lines i.e KKNPP to Tirunelvelli are

implemented &Kept in

service.A/R implementation of

A/R Scheme for KKNPP to

Madurai line will be enabled after

getting clearance from NPCIL HQ

Design group.

50 220 kV SABARGIRI - THENI10-05-

2016/14:43:00

10-05-

2016/15:05:00B - N FAULT KSEB/ TANRANSCO

TANTRANSCO: Temporary fault.

AR lockout at both ends.

51 400/220 kV ICT-3 AT CHITTOOR10-05-

2016/20:14:00

11-05-

2016/22:41:00

RELAY

MALOPERATIONAPTRANSCO To-be-discussed

Annexure-V

Page 7 of 11

52 HVDC BHADRAVATHI POLE 110-05-

2016/09:06:00

10-05-

2016/18:32:00

AUXILLARY POWER

SUPPLY FAILUREPGCIL (WR-I) To-be-discussed

53 400 kV HYDERABAD - KURNOOL11-05-

2016/17:15:00

11-05-

2016/18:02:00B-N FAULT PGCIL (SR-I)/ APTRANSCO To-be-discussed

54220 kV GUMMUDIPUNDI -

SULLURPET

12-05-

2016/12:15:00

12-05-

2016/13:15:00B-N FAULT TANTRANSCO/ APTRANSCO

TANTRANSCO:In 230kV Southern

Bus, Auto Transformer-2 Bus

Isolator 'C'-phase support

insulator flashover. All 230kV

feeders got tripped at remote end

on Zone-2. BBP relay was kept out

of service at the time of fault due

to Auto Transformer-2 pre-

commissioning works.

APTRANSCO:

55 765 KV RAICHUR - SHOLAPUR 116-05-

2016/22:13:00

16-05-

2016/23:28:00R-N FAULT PGCIL (SR-I) To-be-discussed

56 400 kV HYDERABAD - KURNOOL17-05-

2016/13:30:00

17-05-

2016/13:32:00

TRIPPED ON B-N

FAULTPGCIL (SR-I)/ APTRANSCO To-be-discussed

57 220 kV KANIAMPET - KADAKOLA17-05-

2016/16:26:00B - N FAULT KSEB/ KPTCL To-be-discussed

58400 Kv KRISHNAPATNAM -

CHITTOOR -1

17-05-

2016/08:47:00

TRIPPED DUE TO

LA FAILURE AT

KRSPTNM END

APGENCO/ APTRANSCO To-be-discussed

59 400/220 kV ICT-3 AT RSTPS18-05-

2016/17:45:00

18-05-

2016/21:30:00

LV SIDE TRIPPED

DUE TO LINE

TRIPPED ON B-N

FAULT

NTPC-Ramagundam To-be-discussed

60 400 kV CUDDAPPA - CHITTOOR18-05-

2016/02:59:00

DT RECEIVED AT

CUDAPAPGCIL (SR-I)/ APTRANSCO To-be-discussed

Annexure-V

Page 8 of 11

61 400 Kv KUDGI-NARENDRA 218-05-

2016/16:25:00

18-05-

2016/16:38:00B -N FAULT PGCIL (SR-II) To-be-discussed

62 765 KV RAICHUR - SHOLAPUR 118-05-

2016/16:56:00

18-05-

2016/17:35:00Y- N FAULT PGCIL (SR-I)/ PGCIL (WR-I) To-be-discussed

63 765 KV RAICHUR - SHOLAPUR 218-05-

2016/16:56:00

18-05-

2016/17:43:00Y -N FAULT PGCIL (SR-I)/ PGCIL (WR-I) To-be-discussed

64 765 KV RAICHUR - SHOLAPUR 219-05-

2016/15:41:00

19-05-

2016/16:26:00B-N FAULT PGCIL (SR-I)/ PGCIL (WR-I) To-be-discussed

65 220 kV SEDAM - TANDUR19-05-

2016/16:05:00

TRIPPED AT

TANDURKPTCL/ TSTRANSCO To-be-discussed

66 400 Kv GAJWEL - SINGARENI-220-05-

2016/16:53:00

20-05-

2016/18:42:00MALOPERATION TSTRANSCO/ TSGENCO To-be-discussed

67 765/400 Kv ICT-3 at NPS23-05-

2016/07:15:00

23-05-

2016/13:59:00

B-PH DIFFERENTIAL

PROTECTION

ACTED

PGCIL(SR-I) To-be-discussed

68 400/220 kV ICT-1 AT HOODY27-05-

2016/08:08:00

27-05-

2016/08:39:00

Y-PH CT BLAST @

220KV SIDEKPTCL To-be-discussed

69 400/220 kV ICT-2 AT HOODY27-05-

2016/08:08:00

27-05-

2016/08:43:00

Y-PH CT BLAST @

220KV SIDEKPTCL To-be-discussed

70 400 Kv KOLAR - TVLLM27-05-

2016/21:46:00

TRIPPED ON R-Y

FAULTPGCIL(SR-II) To-be-discussed

71 400 Kv SATTENAPALLI - SRISAILAM 128-05-

2016/17:55:00

DISTANCE

PROTECTIONAPTRANSCO/TSGENCO To-be-discussed

72 400 Kv RAICHUR PG - GOOTY 129-05-

2016/00:25:00

29-05-

2016/01:38:00

TRIPPED ON R-PH

FAULTPGCIL(SR-I) To-be-discussed

73 400 Kv RAICHUR PG - GOOTY 229-05-

2016/00:25:00

29-05-

2016/01:39:00

TRIPPED ON R-PH

FAULTPGCIL(SR-I) To-be-discussed

74 220 kV AMBEWADI - PONDA 129-05-

2016/02:40:00

29-05-

2016/02:58:00B-PH FAULT PGCIL(SR-I) To-be-discussed

75400 kV MAHABOOB NAGAR -

RAICHUR

29-05-

2016/02:41:00

TRIPPED ON

BREAKER

PROBLEM @ RCR

TSTRANSCO/KPTCL To-be-discussed

Annexure-V

Page 9 of 11

76 400 Kv RAICHUR - YTPS31-05-

2016/17:20:00

31-05-

2016/18:26:00Y-PH FAULT KPCL To-be-discussed

77 400 Kv BTPS - YTPS31-05-

2016/17:20:00

31-05-

2016/19:06:00Y-PH FAULT KPCL To-be-discussed

78 400 kV VIJAYAWADA - NELLORE 131-05-

2016/18:16:00

31-05-

2016/19:00:00

TRIPPED DUE TO

WINDING

TEMPERATURE

HIGH

PGCIL(SR-I) To-be-discussed

79 220 kV AMBEWADI - PONDA 101-06-

2016/22:53:00

01-06-

2016/23:06:00

DISTANCE

PROTECTIONKPTCL/GOA(SR) To-be-discussed

80 220 kV AMBEWADI - PONDA 102-06-

2016/04:34:00

02-06-

2016/05:01:00

DISTANCE

PROTECTIONKPTCL/GOA(SR) To-be-discussed

81 400/220 kV ICT-2 AT HOODY02-06-

2016/03:09:00

BUSHING

FLASHOVERKPTCL To-be-discussed

82 400 kV MYSORE - KOZHIKODE 202-06-

2016/14:02:00

02-06-

2016/14:17:00TRANSIENT FAULT PGCIL(SR-II) To-be-discussed

83 400 kV RAMAGUNDAM - N'SAGAR 202-06-

2016/19:24:00

02-06-

2016/19:37:00B -N FAULT NTPC/PGCIL(SR-I) To-be-discussed

84 400 kV TALAGUPPA - HASSAN02-06-

2016/16:52:00B - N FAULT KPTCL/PGCIL(SR-II) To-be-discussed

85 220 kV SEDAM - TANDUR03-06-

2016/21:52:00

04-06-

2016/00:36:00B-N FAULT KPTCL/ TSTRANSCO To-be-discussed

86400 Kv SHANKARPALLY-

MAMIDIPALLY

03-06-

2016/20:58:00R-N FAULT TSTRANSCO To-be-discussed

87 220 kV YERANDAHALLY - HOSUR03-06-

2016/21:16:00

03-06-

2016/23:05:00B-N FAULT KPTCL/ TANTRANSCO To-be-discussed

88 GOOTY-SOMANAHALLI03-06-

2016/23:12:00

03-06-

2016/23:40:00TRIPPED PGCIL (SR-I) To-be-discussed

89 GOOTY-NELAMANGALA03-06-

2016/16:06:00

03-06-

2016/16:59:00

TRIPPED DUE TO

TEMP. HIGH

PROTECTION

PGCIL (SR-I)/ KPTCL To-be-discussed

90 765 KV RAICHUR - SHOLAPUR 203-06-

2016/16:08:00

03-06-

2016/19:05:00Y - B FAULT PGCIL (SR-I)/ PGCIL (WR-I) To-be-discussed

Annexure-V

Page 10 of 11

91 400/230 kV ICT-1 AT NEYVELI04-06-

2016/07:51:00

04-06-

2016/08:38:00

TRIPPED ON OVER

LOADNLC To-be-discussed

92 765 KV RAICHUR - SHOLAPUR 204-06-

2016/22:28:00

04-06-

2016/23:03:00

TRIPPED ON B-PH

FAULTPGCIL (SR-I)/ PGCIL (WR-I) To-be-discussed

93 400 kV JSW TORANAGALLU-GUTTUR04-06-

2016/13:57:00

04-06-

2016/14:14:00MASTERTRIP JSWEL/ KPTCL To-be-discussed

94 400 kV NELAMANGALA - HOODY 204-06-

2016/11:31:00

04-06-

2016/11:45:00

TRIPPED AT

HOODY END ONLYKPTCL To-be-discussed

95400 kV WARANGAL - BOOPALPPALLI

1

04-06-

2016/20:45:00

04-06-

2016/22:01:00

TRIPPED ON R-PH

FAULTPGCIL (SR-I)/ TSGENCO To-be-discussed

96 220 kV AMBEWADI - PONDA 104-06-

2016/03:00:00B-N FAULT KPTCL/ GOA To-be-discussed

97 400 kV KHAMMAM - N'SAGAR 105-06-

2016/22:41:00

06-06-

2016/22:54:00

TRIPPED ON B-PH

FAULTPGCIL (SR-I) To-be-discussed

98 400 Kv METTUR - ARASUR-205-06-

2016/14:18:00

05-06-

2016/15:26:00

DISTANCE

PROTECTIONTANGEDCO/ PGCIL (SR-II) To-be-discussed

99 400 kV KAIGA - GUTTUR 108-06-

2016/14:18:00

TRIPPED ON R-PH

FAULTKAPS/ KPTCL To-be-discussed

100 400 Kv HASSAN - UPCL 109-06-

2016/12:16:00

09-06-

2016/12:19:00

TRIPPED AT HSN

END ONLYPGCIL (SR-II)/ KPTCL/ UPCL To-be-discussed

Annexure-V

Page 11 of 11

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 1

SOUTHERN REGIONAL POWER COMMITTEE BENGALURU

Minutes of the Special Meeting on Pending Protection Issues of M/s KPCL held on 03.06.2016

Introduction

A Special Meeting was held on 03rd June 2016 at SRPC Secretariat, Bengaluru to deliberate on the pending

protection issues of M/s KPCL. The list of participants is enclosed at Annexure - I. Sh. S.R. Bhat, Member Secretary (MS), SRPC welcomed Sh. P. Bhaskar, Technical Director, KPCL, and Sh. M.

Shivamallu, Chief Engineer (Elec. Design), KPCL, and other Members and Participants to the Meeting. He

informed that the present meeting had been convened to deliberate on all outstanding pending protection

issues of M/s KPCL. At the outset, he appreciated the active participation of KPCL in all the meetings of

Protection Coordination Sub-Committee (PCSC) of SRPC, and also placed on record the co-operation extended

by KPCL management in resolving/ addressing various protection issues, whether related to protection audit

recommendations or specific recommendations of PSAG & PCSC meetings. However, since certain issues were

observed to be occurring recurrently at their major generating stations such as 400/ 220 kV Raichur TPS and

220 kV Nagjheri PH, it was considered prudent to bring the same to the notice of higher management of KPCL

so that the appropriate action could be initiated in right time. He further stated that certain issues such as

providing auto-reclosure on all 220 kV lines emanating from Kali complex, status of works at Sharavathy

Generating Station, providing double-bus operation at KPCL’s 220 kV generating stations, etc. would also be

discussed in the Meeting.

The following issues were deliberated in the meeting:

1. Recurring Grid Disturbances (GD’s) at Nagjheri Power Station

Sl. No. Date & Time of Event /

Gen loss & Load Loss

Reason

(i) 22.02.2016 at 12:36 hrs

Gen Loss: 500 MW;

Load Loss: 99 MW

220kV lines from Nagjheri PH started tripping from 11:00

hrs due to transient faults in lines. 220kV Narendra-

Ambewadi lines-1&2 got tripped which resulted in loss of

evacuation path to Nagjheri station resulting in tripping of

running Units and complete outage at Nagjhheri power

station. 220kV Ambewadi station also got de-energized

due to tripping of source feeders, i.e., 220 kV Narendra-

Ambewadi-1&2 and 220kV Nagjheri-Ambewadi-1&2.

(ii) 18.03.2016 at 14:40 hrs

Gen loss : 300 MW;

Load loss : 333 MW

Ambewadi Narendra line-2 tripped on fault and 220kV

Ambewadi Narendra line-1 tripped due to over-loading.

Running Units at Nagjheri also tripped during the event

due to tripping of evacuating lines

(iii) 14.04.2016 at 12:29 hrs

Gen Loss: 640 MW

220 kV Nagjheri - Bidnal line tripped on Y-B fault at 12:28

Hrs. At the same time, five running generating units (1,3,4,

5 & 6) at Nagjheri tripped on operation of Generator

Transformer’s back-up Over Current & Earth Fault

protection.

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 2

SLD:

The single line diagram of 220 kV Nagjheri PH as provided by KPCL is given at Annexure-II.

The GD-1 events at Sl. Nos. (i), (ii) and (iii) were discussed in PCSC-51 meeting held on 25.02.2016,

PCSC-53 meeting held on 28.04.2016, and PCSC-54 meeting held on 26.05.2016 respectively. While the

first event was on account of poor maintenance of the 220 kV lines surrounding Nagjhri PH, the second

event was due to non-factoring in of the over-loading of Ambewadi-Narendra lines in the SPS at Nagjheri

PH. The third event was due to tripping of the running Units for a through fault on account of improper

settings of GT’s O/C and E/F protections.

Deliberations:

1.1 Line maintenance issues:

SRLDC stated that since most of the lines tripped on transient single phase to earth fault, regular line

patrolling & clearing the trees/ branches in the ROW of the lines warrants urgent attention by KPCL &

KPTCL.

To this, KPTCL informed that the matter had been taken up with concerned Line Operation and

Maintenance wing to carry out corridor clearance and maintenance as per schedule to avoid frequent

line faults in this corridor. A letter had also been addressed to Chief Engineer, Bhagalkot zone, to ensure

lines in & around Kali complex are maintained in healthy condition.

To avoid tripping of transmission lines on transient faults, KPCL/ KPTCL was recommended to carry out

periodic patrolling of lines, and ensure their proper maintenance by carrying out jungle/ bushing

clearance and trimming of tree branches within the RoW of transmission lines as per the SRPC

transmission line patrolling guidelines (available under the menu item "All Uploads Operation

Miscellaneous Transmission Line Patrolling Protocol / Guidelines for Southern Region" on SRPC

website).

1.2 SPS Modification at Nagjheri PH (NPH)

In both 1 (i) & 1 (ii), it was observed that prior to Nagjheri PH outage, NPH – Hubli lines and NPH – Bidnal

line were under OPEN condition due to bus shutdown at Hubli SS and/or transients faults on the

respective lines. Under these conditions, one of the Ambewadi – Narendra D/C lines got tripped on a

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 3

transient fault, and led to the over-loading of the other line. As a result, the other line also got tripped

on O/C protection. Since the Nagjheri – Kodasalli lines had already been kept OPEN as per SLDC, KPTCL

instructions, NPH was effectively left with no evacuating lines, which ultimately led to the tripping of

NPH running Units on over-frequency.

In this regard, KPTCL explained that the existing SPS (given at Annexure-III) had been designed to

operate with the loci of faults lying on the Nagjheri bound 220 kV lines. Accordingly, it was configured to

operate with a delay of 1 sec in the event of over-loading (current exceeding 590 A) of any of its

evacuating lines, and was not co-ordinated with the operation of over current protection of Ambewadi-

Narendra D/C lines. Now in the instant cases, the loci of faults were on the lines emanating from the

substations surrounding Nagjheri, but away from it. As a result, even though the SPS at Nagjheri PH was

in healthy condition, it had not operated due to non-fulfilment of the conditions required w.r.t loading

and current flow on the lines.

It was further observed from the existing SPS that only that running Unit out of Unit-3 and Unit-6 with

maximum generation would be tripped as a result of SPS operation. As such, further reduction/ backing-

down of generation at NPH was not possible if Unit-3 and Unit-6 were already under outage condition.

This implied that a loss to the extent of 600 MW (by virtue of Ngajheri PH outage) was very much a

reality if tripping of Ambewadi – Narendra D/C lines were to take place under such conditions.

On this, SRPC/ SRLDC opined that while modifying the existing SPS so as to factor in over-loading of

Ambewadi-Narendra lines could offer immediate relief, it would do well for KPTCL as a long-term

solution to undertake re-conductoring (with HTLS type of conductors) of 220 kV Nagjheri – Ambewadi

D/C line, 220 kV Ambewadi – Narendra D/C line, 220 kV Nagjheri – Kodasally D/C line, and 220 kV Kaiga

– Kodasalli S/C line.

To this, KPTCL agreed to take into account all factors affecting NPH generation including over-loading of

Ambewadi – Narendra D/C lines, and assured that the thus suitably modified SPS would be put into

service after taking necessary approval from their management. KPTCL also agreed to take up

re-conductoring of the above mentioned 220 kV lines with their management.

The modified SPS at NPH as proposed by KPTCL is given at Annexure-III.

SRLDC and SLDC, KPTCL were requested to kindly go through the details of the above proposed SPS

with focus on the limiting values of various time-delays & current flows, and furnish their comments to

KPTCL for incorporation of the same.

KPTCL was recommended to implement the final version of the modified SPS at Nagjheri PH at the

earliest.

KPTCL was further recommended to actively undertake re-conductoring (with HTLS type of conductors)

of 220 kV Nagjheri – Ambewadi D/C line, 220 kV Ambewadi – Narendra D/C line, 220 kV Nagjheri –

Kodasally D/C line, and 220 kV Kaiga – Kodasalli S/C line, and furnish an action plan for implementing

the same.

1.3 Revising GT back-up protection settings appropriately at Nagjheri PH

SRPC/ SRLDC stated that the operation of Generator Transformer’s back-up Over Current & Earth Fault

(high-set) protection for a through fault was not in order (the fault current was stated to be 3.2 kA).

Accordingly, there was a need to revise the settings of GT’s back-up O/C and E/F protections considering

their individual contribution to solid bus fault at 220 kV bus of Nagjheri PH.

To this, KPCL informed that they had revised GT’s back-up protection settings in the recent past only

from 5 A to 7.5 A. However, in view of the current GD, Discrete Relay High set values had been

re-calculated and assured that the same would be loaded in stages in consultation with OEM of Relays

(M/s Andritz).

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 4

1.4 Putting 220 kV Nagjheri-Kodasalli lines into service

It was noted that the 220 kV Nagjheri- Kodasalli D/C lines had been kept opened based on SLDC, KPTCL

instructions. In this regard, it was pointed out that closing of these lines could have averted this grid

disturbance since there was sufficient generation at all Generating Stations (esp. Nagjheri) in Kali

Complex, and brought to KPCL & KPTCL’s attention the study carried out in respect of similar grid

disturbance that occurred there on 22.02.2016 at 12:36 hrs. (Minutes of PCSC-51 issued vide SRPC letter

no: SRPC/SE-III/PCSC-51/2016/ 1702-35 dated 16.03.2016, where it was recommended to put 220 kV

Kodasalli - Nagjheri D/C lines into service if more than 200 MW generation from Kali Complex (with

Nagheri Contribution not less than 50 MW) is ensured on sustained basis.

To this, KPCL informed that Nagjhari- Kodasalli Lines 1 & 2 had been kept in service since 23.05.2016 @

08.06hrs.

2. Trippings involving 400/ 220 kV Raichur TPS

Sl. No. Details of Event Date & Time

Reason

(i) Tripping of 400 kV Raichur TPS -

Mahboobnagar line

05-04-2016

at 10:23 hrs

Line tripped on operation of Backup

impedance protection of line reactor.

Direct trip was received at Mahboobnagar

end.

(ii) Tripping of 400kV Raichur TPS Bus-2

13-04-2016 at 21:12 hrs

Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed. Unit-4 got tripped on operation of Generator Differential, Reverse power & LBB protection. Operation of LBB protection led to tripping of BUS-2 at RTPS

(iii) Tripping of Units at Raichur TPS Gen loss: 760 MW

15-04-2016 at 15:36 hrs

During testing of retrofitted distance protection in 400kV Raichur-2 feeder, LBB protection trip DC got extended to Bus trip. This resulted in tripping of 220kV bus at RTPS and subsequently tripping of all connected 220kV elements. Unit-4 which is connected to 400kV Bus got tripped due to tripping of Station Utility Transformer that is connected 220 kV bus

The above Grid Incidents (GI’s) were discussed in PCSC-54 meeting held on 26.05.2016. While the first GI

seemed to be on account of mal-operation of Line Reactor back-upprotection, w.r.t. the second GI it was

informed that during the synchronization process of Unit-4, when the excitation voltage was at 15 kV,

the Y-Pole of Tie-breaker (of Unit-4) got blasted. As a result, Unit-4 got tripped on Generator Differential,

Reverse power & LBB protection. Operation of LBB protection led to tripping of 400 kV Bus-2 at RTPS.

Similarly, the third GI was also not in order as the 220 kV side seemed to be on single-bus operation.

Further, there was also a need to provide alternative source to Unit-4 auxiliaries, esp. when the SUT,

from which the Unit-4 auxiliaries are presently being fed, goes out.

SLD:

The single line diagram of 400/ 220 kV Raichur TPS as provided by KPCL is given at Annexure-II.

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 5

Deliberations:

2.1 Tripping of 400 kV Raichur TPS -Mahboobnagar line on 05.04.2016 at 10:23 hrs

SRPC/ SRLDC stated that operation of back-up impedance protection of Line Reactor (LR) at RTPS end on

400 kV Raichur TPS - Mehboobnagar line was not in order as there was no signature of any fault in the

PMU plot around the time of occurrence of this tripping.

To this, KPCL stated that it was a typical case of mal-operation of the corresponding electro-mechanical

relay, and informed that they were ready to take LR out of service, if permitted, in view of the short

length of the line. On this SRLDC stated that even though it was a short line, due to prevailing of high

voltages at RTPS, best option would be to convert this LR into a Bus Reactor.

The issue was further discussed, and it was noted that there was neither the availability of additional

circuit breaker nor the space required for reconfiguring the bays. As such, it was recommended to KPCL

to keep the referred electro-mechanical back-up impedance protection relay under observation, and

replace it with a spare at the earliest.

2.2 Tripping of Raichur TPS 400 kV Bus-2 on 13.04.2016 at 21:12 hrs

KPCL informed that Y-ph Pole of Tie-breaker of Unit-4 at RTPS failed while synchronising it. Unit-4 got

tripped on operation of Generator Differential, Reverse power & LBB protection protections. It was

explained that due to surface conduction over the Unit-4 Tie-breaker, LBB relay of 400 kV Bus-2 got

operated leading to tripping of all breakers connected to it. The reason for surface current was attributed

to the deposition of ash, heavy mist & humidity on account of Unit-4’s proximity to cooling towers.

In this regard, SRPC/ SRLDC brought to KPCL’s attention the occurrence of similar event due to LBB

operation of Main & Tie breakers of Unit-7 on 12.11.2015 at 00:30 hrs, when it was recommended

among other things to provide dedicated breaker flashover protection, and to take necessary preventive

measures such as measurement of dynamic contact resistance, and over-hauling (hot-line washing) of

breakers at regular intervals to ensure healthiness of breakers.

To this, KPCL informed that hot-line washing of breakers is already in place. Further, they have also

initiated steps (tendering is in progress) for applying RTV Silicone high voltage insulator coatings to all

ceramic insulators of equipment like CT, PT, CB, Isolators etc.

When enquired about providing breaker flashover protection, KPCL assured that they would look into it.

To this, it was explained that breaker flashover is an abnormal condition and may result in severe

damage to capital equipment like Generator and Generator Transformer. Additionally it may also result

in explosion of Circuit Breakers which can damage the nearby equipment in Switchyard and put

Substation personnel at risk. As such, detection of flashover reliably and operating the protection system

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 6

to isolate the affected breaker and generator in minimum possible time is all the more important, and

informed that such a protection can be implemented using a logic based on immediate sensing of arc

current supported by breaker status to reliably declare a flash. In this regard, papers contributed by

Adani personnel on (i) “Adaptive Logic for Breaker Flashover Protection”, (ii) “External Flashover of

Generator Circuit Breaker in Coastal Power Plants having Air Insulated Switchyard”, and (iii) “Practical

Interlock Logics to prevent undesired Circuit breaker closing, Isolator opening & charging of Bay in

Substations using IEDs” are enclosed at Annexure-IV for kind perusal and necessary action.

Thus, KPCL was recommended to undertake the following remedial measures to avoid breaker

flashovers:

replacing all porcelain insulators with composite insulators

carrying out hot-line water washing of all insulators on regular basis.

applying Room Temperature Vulcanizing (RTV) Silicone high voltage insulator coatings to all bus-

connected ceramic insulators of equipment like CT, PT, CB, Isolators etc.

KPCL was also recommended to take steps to provide dedicated breaker flashover protection to all

breakers at Raichur TPS at the earliest.

2.3 Tripping of Units at Raichur TPS on 15-04-2016 at 15:36 hrs

KPCL informed the following:

KPCL informed that at the time of the incident, Unit Auxiliary Transformer of Unit-4 was under

maintenance; hence Unit-4’s auxiliaries were being fed from the Station Transformer-4 (ST-4). As ST-4

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 7

was deriving its power from 220 kV bus, and since 220 kV side was being operated on single-bus, LBB

operation of 220 kV Bus led to tripping of ST-4. This failure of supply to Unit-4 auxiliaries resulted in

tripping of Unit-4.

In this regard, SRLDC enquired about the reasons for not providing double-bus operation at 220 kV level

at RTPS, and the general practice being adopted w.r.t. double-bus operation at the other generating

stations of KPCL. To this, KPCL informed that excepting at 220 kV RTPS, its all other 220 kV generating

stations were being operated on double-bus operation only.

It was noted with concern that in spite of the availability of two buses along with healthy bus-coupler,

all generating units (1, 2 & 3) and the loads/ feeders at 220 kV were put on single bus operation at 220

kV RTPS. As such, KPCL was recommended to put in service the double-bus operation at 220 kV RTPS

by suitably distributing loads within 15 days.

3. Revival schedule & status of works in progress at Sharavathy Generating Station.

KPCL informed the following:

Units- 6,7 & 8 and 2 lines (Shimoga 3 & 4) are in service.

Order placed on M/s ABB on 22.03.2016 for balance 7 Units & 7 lines with DCS adapting state of art technology.

Implementation schedule:

KPCL also informed that Units – 9 & 10 would be synchronized by 06.06.2016; and all other remaining Units would be synchronized by 30.06.2016.

4. Auto-Reclosure scheme implementation on all 220 kV lines emanating from Kali Complex

The issue has been deliberated in various PCSC meetings. Since most of the faults that occur on 220 kV

lines emanating from Generating Stations in Kali Complex are transient single phase to ground faults, the

outages such as those mentioned at Sl. No. 1 could be avoided by providing A/R on the 220 kV lines of

Kali Complex.

When enquired about the action initiated by KPCL in this regard, KPCL informed the following:

Implementation of Auto-reclosure scheme would be taken up after retrofit of new version Numerical

Distance relays for Main-2 protection.

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 8

PO had been placed on M/s Schneider Electric Infrastructure Ltd. for supply of Numerical protection

relay to be used as Main-2 protection. Materials received at site. Erection work would be taken up

shortly.

However, when KPCL expressed the apprehension of their GT’ breakers switching on to high fault

currents, it was clarified that the time-differentiated A/R scheme as detailed in the minutes of PCSC-51,

(also reproduced below) can be implemented:

“In this, after a line is opened from both ends (generator end & remote end) on

A/R operation, the remote end will be auto-reclosed as usual after the elapse of

its dead-time (say, 1 sec). However, the generator end relay will check for the

line voltage after elapse of an elongated dead time (say 1.3 or 1.5 sec; here the

additional 0.3 or 0.5 sec has been included as a safety time margin). If the line

voltage so sensed is healthy & normal (which implies that the fault has already

been cleared), then generator end will be auto-reclosed; else 3-ph trip will be

given at generator end to open the other two phase poles.”

On this, KPTCL stated that by above scheme even though the generator end is effectively prevented

from closing on to fault, there is also a need to prevent auto-reclosing altogether when the fault current

is prohibitively high, as it could lead to high-voltage phenomena, and result in cascade tripping of the

connected lines.

The merit in the KPTCL’s argument was thoroughly discussed, and it was agreed to implement blocking

auto-reclosure on heavy fault currents (say 70 % of the corresponding bus-fault level) on experimental

basis on any one line connected from Sharavathy Generating Station as explained below:

“In this, additionally an Over Current (O/C) element is kept enabled to operate at

70 % of the corresponding bus-fault level at both ends of the line, and is

configured to block A/R at the originating end alongside sending Direct Trip (DT)

command to the other end. By this, as long as the fault current is less than the set

value of O/C element, auto-reclosure will be attempted for the tripped line in

accordance with the above detailed time-differentiated A/R scheme. However,

when the fault current exceeds the set value of the O/C element, A/R function will

be blocked at the originating end, and DT will be sent to the other end”.

Thus, KPCL was recommended to implement auto-reclosure on all 220 kV lines emanating from Kali

complex in accordance with the above detailed time-differentiated A/R scheme.

Further, KPTCL, in coordination with KPCL, was requested to implement and validate on experimental

basis the above detailed logic for blocking Auto-Reclosure on heavy fault currents on any one line

connected from Sharavathy Generating Station, and furnish a report on the efficacy/viability of the

scheme for implementation on all transmission lines.

5. Tap-Change of KPCL Stations

Station Unit Present tap &

Corresponding

voltage (in kV)

Recommended Tap &

Corresponding

Voltage (in kV)

Kadra All units 7 & 225.5 8 & 222.75

Kodasalli All units 7 & 225.5 8 & 222.75

Sharavathy 9 2 & 231 4 & 220

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 9

KPCL informed that the Taps at Kadra and Kodasalli Power Houses had been kept at 7/225.5 to suit

system condition against the recommended value of 8/225.75 for matching generator voltage with

system voltage. Similarly, at Sharavathy Generating Stations (SGS), the 9th Unit GT-tap could not be

changed due to technical problems. KPCL informed that tendering is in progress for procurement of

115 MVA Generator transformers, after which the required tap would be provided at SGS.

On this, SRLDC explained that since the system voltage for synchronization is 220 kV at Kadra & Kodasalli,

and the recommended value is nearer to this, KPCL’s reservations on changing to recommended tap are

mi splaced.To this, KPCL agreed to look into the issue, and adjust tap positions accordingly.

KPCL was recommended to adopt the SRLDC recommended tap-positions at their Kadra (all Units),

Kodasalli (all Units) and SGS (Unit-9) stations at the earliest.

6. Compliance of pending Recommendations of the following Power System Analysis Group (PSAG) Meetings

The status of recommendations of PSAG-3 held on 04.09.2013 to analyze the multiple trippings that at

Sharavathy HPS on 18-08-2013 is given at Annexure-V.

The status of recommendations of PSAG- 6 held on 05.02.2014 to analyze the multiple trippings at

Raichur TPS on 26-01-2014 and 30-01-2014 is given at Annexure-VI.

The status of recommendations of PSAG-10 held on 12.11.2014 to analyze the Grid Disturbances at

Kadra, Kodasalli and Kaiga Power Stations that occurred on 26-09-2014 and 05-10-2014 is given at

Annexure-VII.

The status of recommendations of PSAG-13 held on 22-23 April, 2015 to analyze the cause of multiple

trippings that took place at RTPS and Raichur-PG on 09.03.2015 & 11.04.2015 is given at

Annexure-VIII.

It was noted that generally recommendations involving procurement activities are pending. As can be

seen from the furnished status, the erection & commissioning activities for the recommended works are

under progress.

7. Pending Implementation of PCSC Recommendations

The latest status of compliance of recommendations of various PCSC meetings relating to KPCL Stations is

given at Annexure-IX.

It was noted that steps had been taken to implement various PCSC recommendations relating to revision

of specific relay settings, enabling of A/R scheme, replacement of old electromechanical relays with

numerical relays at KPCL Stations, etc.

8. Protection Audit Recommendations (Phase- I & II)

The latest status of compliance of Protection Audit recommendations (Phase-I and Phase-II works) pertaining

to KPCL Stations is given at Annexure-X.

It can be seen from the furnished status that all works of Phase-I & Phase-II have been targeted to be

completed before 30.12.2016, the dead-line for which KPCL has committed before Hon’ble CERC in their

application seeking time-extension for implementing protection audit recommendations relating to their

stations.

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 10

9. High resistance faults are frequently observed in 220kV lines in Kali complex due to the dense vegetation. Faults are often observed to be cleared by back up protections. The resistive reach of distance protection relays to be reviewed along with proper vegetation management. KPCL informed that they were seized of the matter, and assured that the Resistive reach of lines would be

revised in co-ordination with KPTCL.

10. Fault level at Raichur TPS

During failure of R-phase CT of 400/220kV ICT-1at Raichur TPSat 21:44 Hrs on 01-05-2016 the fault current

recorded in DR was 36 kA. Suitable actions need to be planned as fault level may exceed 40kA in near future.

To take care of the situation arising out of 400 kV RTPS bus fault level exceeding 40 kA, KPCL informed

that in RTPS area switchgear which can withstand such fault level only are being put into service in recent

days. Further, materials with design specifications considering 50 kA only are being procured. The same

will be CONSIDERED and adopted in all future replacements.

11. Differential protection for 400kV lines

400kV Raichur-Raichur TPS line-1&2 and 400kV Raichur-YTPS and in future lines from Bellary pooling station

to nearby generating TPS are to be provided with differential protection as frequent over-reach is observed

with distance protection relays.

KPCL informed that DIFFERENTIAL PROTECTION for 400 kV lines would be provided in consultation with

KPTCL and considering site feasibility.

12. Faulty distance relay in 400kV RaichurTPS-YeramarusTPS line

400 kV RTPS-YTPS line is tripping from Raichur TPS end for any through fault due to problem in distance relay

at RTPS end.

KPCL informed that the SOTF logic implemented in Micom P444 distance relay at RTPS end on 400 kV RTPS –YTPS line had been wrongly configured with continuous enabling, due to which whenever any fault takes place on down-stream network, it is invariably acting to trip the line.

Now the ALSTOM make P444 relay settings were revised on 01.05.2016 in consultation with M/s

ALSTOM, and the line is found to be stable.

13. D.R and station event logger to be triggered with operation of Main and Back-up protections of transmission

line/ generator /bus-bar protection with proper time synchronization for proper analysis.

KPCL informed that protection relays with built-in Disturbance Recorder (DR) and Event Logger (EL) with

facility to synchronize with GPS were being procured and commissioned.

To this SRPC/ SRLDC while appreciating KPCL’s initiative in procuring new protection (numerical) relays

with DR and EL and time-synchronization facilities, informed that the new relays must be suitably

configuring for recording even those events that occur on operation of back-up protections of

transmission line/ generator /bus-bar. To this, KPCL agreed to take necessary action for capturing events

on back-up protection operation.

Annexure-VI

Minutes of the Special Meeting held on 03.06.2016 with M/s KPCL Page 11

14. Integrity test for Station earth mats in KPCL stations

As per CPRI report, improper earthing was one of the reasons attributed for fire incident at Sharavathy

power house. Station Earth mat integrity test need to be carried out at all KPCL power station as a

precautionary measure.

KPCL informed that New Earthing System as per design of M/S CPRI would be put into service, which

would be in addition to the existed earth mat. KPCL also assured that Station Earth-mat integrity test

would be carried-out at all KPCL power stations as a precautionary measure.

Vote of Thanks

MS, SRPC thanked Technical Director, KPCL and other Officials from KPCL & KPTCL for participating in the

Meeting. He hoped that with active cooperation, visible improvement would be witnessed in the near future

on these pending protection issues.

*****

Annexure-VI

Annexure-I

Annexure-VI

Annexure-I

Annexure-VI

Annexure-II

Annexure-VI

SHAHPUR-1

SHAHPUR-2

Annexure-II

Annexure-VI

SPS Logic at Nagjhari (15-08-12)

Revised to 600MW after 26-06-14.

EXISTING SPECIAL PROTECTION SCHEME FOR NAGHJARI GENERATING STATION : FLOW LOGIC

Tripping of Hubli-Sirsi 1 &2 lines

Or Tripping of Bidnal-Harthi 1 &

2 lines will lead to tripping of

Generating units U3 0r U6 @

Nagjhari, based on the condition,

if Total Gen (including Kodasalli

lines inflow @ Nagjhari) is > 900

MW

KODASALLI 2

KODASALLI 1

INPUT FROM GEN AND KODASALLI LINES

TRIP MAX OF G3 AND

G5

G3

G6H

UB

LI 1

CURRENT <30 A OR BREAKER TRIP

LINE CURRENT

BREAKET TRIP

G1 TO G6 GEN IN MW

ANY ONE HIGH

CURRENT <30 A OR BREAKER TRIP

CURRENT <30 A OR BREAKER TRIP

CURRENT <30 A OR BREAKER TRIP

CURRENT <30 A OR BREAKER TRIP

CURRENT <30 A OR BREAKER TRIP

LINE CURRENT

BREAKET TRIP

LINE CURRENT

BREAKET TRIP

LINE CURRENT

LINE CURRENT

LINE CURRENT

BREAKET TRIP

HU

BLI

2

BID

NA

L 1

BID

NA

L 2

AM

BEW

AD

I 1

AM

BEW

AD

I 2

HU

BLI

1H

UB

LI 2

BID

NA

L 1

BID

NA

L 2

AM

BEW

AD

I 1A

MB

EWA

DI 2

KO

DA

SALL

I1

KO

DA

SALL

I 2

LINE CURRENTS

ANY LINE CURRENT >590 A (DELAY 1 SEC)

ANY LINE CURRENT <30 A OR BREAKER TRIP ORANY DI COMMAND FROM HUBLI OR BIDNAL AND TOTAL GEN >900 OR ANY LINE CURRENT >590 A

TOTAL GEN

ANY LINE CURRENT<30 A OR BREAKER TRIP AND TOTALGEN >900

LIINE LOAD

LIINE LOAD

MAX OF G3 AND G6

TOTAL GEN

HU

BLI

BID

NA

L

SPS DI INPUTS FROM RTU

ANY DI COMMAND FROM HUBLI OR BIDNAL AND TOTAL GEN >900

Annexure-III

Annexure-VI

SPS Logic at Nagjhari (15-08-12)

Case 1e) Any line Current is > 590 A OR In Bidnal-Harthi 1 & 2 & Bidnal-Soundatti if any line current is < 30A or Breaker tripped, DI command shall be sent from Hubli to Nagjhari & Gen> 600MW then one unit which is generating Max will be tripped.

MODIFIED SPECIAL PROTECTION SCHEME FOR NAGHJARI GENERATING STATION : FLOW LOGIC(Revised as on June 2016)

Case 1a) Any line Current is > 590 A for 1.5 sec & Gen> 600MW then one unit which is Max of 6 units will be tripped.

Case 1b) Any line Current is > 590 A for 2 sec OR in Ambewadi-Narendra 1 & 2 lines if any current is > 700A, DI command shall be sent from Ambewadi to Nagjhari & Gen> 300MW then one unit which is generating Max will be tripped.

Case 1c) Any line Current is > 590 A for 2.5 sec OR in Ambewadi-Narendra 1 & 2 lines if any current is < 30A & the other line current is > 800A, DI command shall be sent from Ambewadi to Nagjhari & Gen> 200MW then one unit which is generating Max will be tripped.

Case 1d) Any line Current is > 590 A OR in Hubli-Bidnal 1 & 2 if any line current is < 30A or Breaker tripped, DI command shall be sent from Hubli to Nagjhari & Gen> 600MW then one unit which is generating Max will be tripped.

INPUT FROM GEN AND KODASALLI LINES

TRIP MAX OF G1 TO

G6G

G1 TO G6 GEN IN MW

AMBEWADI 1

HUBLI 1

ANY LINE CURRENT >590 A

TOTAL GEN

ANY LINE CURRENT >590 A , Gen> 300MW (DELAY 2SEC)

AMBEWADI 2

In Ambewadi-Narendra 1 & 2 if any line current >700A, DI command shall be sent from Ambewadi to Nagjhari

In Ambewadi-Narendra 1 & 2 if any line current is < 30A & the other line current>800A, DI command shall be sent from Ambewadi to Nagjhari

HUBLI 2

HUBLI 3

In Hubli-Bidnal 1 & 2 if any line current is < 30A or Breaker tripped, DI command shall be sent from Hubli to Nagjhari

Bidnal

In Bidnal-Harthi 1 & 2 & Bidnal-Soundatti if any line current is < 30A or Breaker tripped , DI command shall be sent from Hubli to Nagjhari

ANY LINE CURRENT >590 A , & Gen >600 MW (DELAY 1 .5 SEC)DELAY 1.5 SEC

ANY LINE CURRENT >590 A DELAY 2 SEC

ANY LINE CURRENT >590 A DELAY 2.5 SEC

ANY LINE CURRENT >590 A , Gen> 200MW (DELAY 2.5 SEC)

ANY LINE CURRENT >590 A

DELAY 1 SECANY LINE CURRENT >590 A , Gen> 300MW (DELAY 1 SEC)

ANY LINE CURRENT >590 A DELAY 1 SEC ANY LINE CURRENT >590 A , Gen> 300MW (DELAY 1 SEC)

Annexure-III

Annexure-VI

Adaptive Logic for Breaker Flashover Protection of Generator. Sanjay Bhatt

Protection Automation and Metering Group Adani Power Training and Research Institute

Adani Power Limited, Ahmedabad [email protected]

1. ABSTRACT:

Flashover can occur on any breaker in the network where an overvoltage condition is present, but the probability is higher for breakers being used to synchronize two isolated power systems; e.g. on generator breakers, line breaker connecting two separate sources or grids. For Generator/line breaker, the Period is considered as critical in view of withstanding rise in voltage vector appearing across poles of Circuit Breaker and the arc quenching process before generator/line synchronization, or just following generator/line tripping respectively. The circuit breaker for above said applications for must be designed capable of maintaining the sufficient insulation level to withstand the same. The detection of flashover reliably and operating protection to isolate the affected breaker and generator in possible minimum time calls for a logic based on immediate sensing of arc current supported by breaker status to reliably declare a flash. This paper describes the logic adapting the numerical relaying logic blocks with current status different from conventionally used and also described in IEEE guideline for Generator Protection C37.102.

2. KEYWORDS: Breaker Flashover, Generator Protection for GT Breaker flashover, unintended arc across Generator breaker

3. INTRODUCTION:

(I) It is because the vectors of the protected generator and grid vector across circuit breaker poles are slipping with respect to a power system. This will lead to a condition to establish at least twice rated phase-neutral voltage across the generator circuit breaker. Due to the system and machine operation condition it is quite often possible that even higher voltage may be established. This will lead to establishment of arc between two poles of circuit breaker, which may be internal or external, leading to failure of breaker damaging self and also nearby equipments and persons. Further the establishment of arc will also lead to the asynchronous energisation of Generator with grid and create oscillation damaging Generator Transformer / Generator. Detecting the flashover The abnormal rise in voltage just after generator tripping is most likely due to following reasons,

Prime mover failure: which is associated by the excitation level not matching instantly with the lowering of active power, where the pre-failure level of excitation might be maintained until AVR action takes place.

AVR malfunction: this is associated with failure of AVR to discharge energy through discharging resistor at the time of tripping boosted by residual flux.

Annexure-IV

Page 1 of 23

Annexure-VI

2 Adaptive Logic for Breaker Flash over protection of Generator.

The peak to peak voltage appearing across circuit breaker is indicated at Fig.1 below.

During the synchronization process, the out-of-phase angle between breaker contacts changes from 0 to 360 degrees continuously. Voltage between breaker contacts reaches its maximum instantaneous value when the angle difference between the voltages is 180 degrees, with a magnitude equal to double the nominal phase-to-ground peak voltage; posing severe stress to the insulation. May also result in out of step and swing.

The flash over thus occurred in most of the cases are of single phase in nature as because of probability of maximum peak to peak voltage at a time is for one phase and very rare may be of two phases depending up on deterioration of insulation and repeated peak across each phase.

(II) Detection of Flash over The detection of arc as a fault is very tricky due to lower magnitude and also resembling the breaker status with selectivity among various normal and abnormal grid behavior and remote fault. The arc current will always reflect as a Zero sequence or Negative sequence current which can be detected typically as under.

Fig 1- Typical One and Half CB arrangement possible breaker flash over due to peak to peak voltage across CB open contacts Breaker

Fig 2a- Typical CT connection to detect breaker arc current as residual current for Generator directly connected to Grid

Fig 2b- Typical CT connection to detect breaker arc current as residual current for Generator connected to Grid through Transformer.

Annexure-IV

Page 2 of 23

Annexure-VI

3 Adaptive Logic for Breaker Flash over protection of Generator.

Typically the detection of Neutral over current from Generator or Generator transformer as referred in fig (2a & 2b) with Breaker OPEN status is interpreted as breaker flash over condition, and after certain small time delay tripping is declared out. Alternatively detection of Negative sequence current at Generator Neutral and phase side with Breaker status is also used for detection of breaker flash over condition.

(III) Action: Tripping of associated bus is essential here, because, merely tripping of Generator or excitation will also initiate tripping of Generator breaker and still the breaker is shunted by flash arc current, with the breaker is already in OPEN status, will subsequently cause initiation of LBB and after certain time delay of LBB timer will trip Bus breakers, which is delayed tripping as per LBB setting and initializing scheme.

(IV) Reliability & Selectivity.

(a) Limitation of above logic remains always within the reliability of the breaker status, because defective status of breaker obtained through breaker auxiliary switch many times falsify due to switch and related gearing alignment and contact issues. During the defective status of breaker associated with remote fault or short duration unbalance due to auto reclosing will cause to operate the

logic undesirably causing tripping of Generator and bus also. However use of GT neutral current with interlocking of GTCB may lead to mal-operation when the Breaker contact is defective, which enables the function during normal operation of unit. Further the setting of IN for Flash over detection is kept low enough for effective detection of flash current therefore any earth fault or unbalance in the grid / line may lead to operation of the function. Use of Generator Neutral CT will avoid the possibilities of above mal-operation during grid disturbances. However pure single phase flash may not be reflected at Generator Neutral side because of the zero sequence isolation at generator side for faults on GT side.

(b) In case of Generator connected with one and a half breaker bus arrangement detection of breaker flash over if actual, will not identify the breaker (Main or Tie) which has undergone flash over. Pl. refer fig 1, where it has been indicated that the Generator / Line can be connected either from Main or Tie breaker and therefore the flash over condition may be for either of two breaker. Thus the automatic and reliable detection of the breaker which has undergone the mishap must be identified and output action should be relevant to the identification. It is now obvious that action to isolate the Generator from Grid should be separate for each condition with unique identification. Merely detecting breaker flash over condition from the breaker status (composite may be of Main and Tie) and neutral current from Generator Transformer or Generator, with action for Tripping of Bus bar and Class A tripping for Generator is not sufficient as well not truly as per requirement defeating the aim for Breaker flash over protection intended so.

Above limitation for reliability and selectivity will place a threat to undesired tripping, delayed tripping or stability aspects too.

& Breaker OPEN Status

IN>

I2p>

I2n>

TRIP Excitation& BUS

& Breaker OPEN Status

TRIP Excitation& BUS

Fig 3- conventional logic to detect breaker flash over

Time

Time

Annexure-IV

Page 3 of 23

Annexure-VI

4 Adaptive Logic for Breaker Flash over protection of Generator.

(V) Solution: Addressing above limitations with feasible solution is possible with following considerations. As earlier discussed Broadly two criteria are required to detect breaker flash over (i) Breaker OPEN status (ii) sensing of Neutral current at GT or Negative sequence current at Generator terminal and (iii) third one essential for One and Half breaker Bus arrangement is, identifying the affected breaker. The output actions are then decided and forwarded with suitable circuit schemes. (a) Detection of Breaker Status.

Indirect assessment of breaker pole status can only be done by detecting flow of current through all three phases simultaneously registering a status in logic block and removing also the register status as low, i.e. using flipflop block triggered by current threshold. Also as per IEEE GUIDE FOR AC GENERATOR PROTECTION: Std C37.102-1006, 4.7.1 Open generator breaker flashover protection: ‘Generator breaker flashover may also be detected by breaker pole disagreement relaying. This relay monitors the three-phase currents flowing through the breaker and senses whether any phase is below a certain low threshold level (indicating an open breaker pole) at the same time that any other phase is above a substantially higher threshold level (indicating a closed or flashed-over pole).’ Logic using FlipFlop :

Above logic criteria are indicated at Fig 4. The flow of current through circuit breaker at HV side of Generator Transformer is considered as Phase current (Iph) and IN as GT neutral current. The OPEN status is detected when all three phases detect current below 2% (or practically as low possible setting available in relay which can be detected reliably. The OPEN status implies isolated

condition of Generator from grid and SET the FlipFlop. The output of FlipFlop makes input of AND gate high arming for Breaker flashover protection active. On detection of neutral current in GT or Negative sequence current at Generator will operate breaker flash over protection trip output. The normal operation of Generator can be considered as (i) Before & During synchronizing (ii) After Synchronizing and (iii) Grid fault when Generator is normal in service (iv) After isolating from grid. (i) Before & during synchronizing there

is no current flow and hence FlipFlop O/P is High. There will not be Iph and IN hence keeping the logic O/P as low.

(ii) Immediate after synchronizing there will be Iph >5% (or to be set as possible initial loading normally) resetting the FlipFlop after 200 mS.

(iii) Machine running normally will also prevail condition (ii) above.

(iv) After tripping of machine there will be Iph<2% as set above will immediately put function in service.

Fig 4- Breaker open status Detection logic based on current threshold using SR FlipFlop

SR Flip Flop

S

R

O

IPh <2% 3 Phase

IPh > 5% 3 Phase

T = 200 mS

& IN> 10 to 20%

T = 100 mS

TRIP ALL / BUS TRIP

Iph= Phase current, IN = GT Neutral current

For 1-1/2 Breaker bus, separate logic for Main and Tie breaker path current.

Annexure-IV

Page 4 of 23

Annexure-VI

5 Adaptive Logic for Breaker Flash over protection of Generator.

Logic using AND –OR blocks : Some of the basic versions of IEDs do not have the Flip Flop logical blocks, for which following logic using basic AND – OR and Timer blocks can be used as indicated at Fig-5 here under.

The lower current threshold for any one phase is monitored for OPEN status, this implies for resetting only when all three phases have current more than 2% i.e. all poles closed. The drop out timer is intended for keeping function armed for 200 mS. after synchronizing during which practically picking up of load by Generator more than 5%.

All four conditions mentioned in earlier paragraph for Generator are addressed here

also detecting reliably the breaker flash over condition.

The IN setting for 10 to 20% is intended for detecting lower arc current as low as 10% keeping in consideration normal maximum unbalance current.

The delay in output is chosen as 100 mS for stability and reliability purpose considering normal breaker closing time and inherent difference in closing of individual pole and also initial unbalance current owing to measurement and magnetizing effect for lower magnitude.

OUTPUT Action:-

The output action of the protection must isolate the Generator from grid and also removal of excitation to Generator. The conventionally action for a LBB protection is similar to the required one for Breaker Flashover condition.

The difference here is the detection at a lower magnitude of current without any trip initiation and also operating time is much less than typical LBB time of 200 to 250 mS.

Fig 5- Breaker open status Detection logic based on current threshold using AND-OR blocks.

Iph= Phase current, IN = GT Neutral current

For 1-1/2 Breaker bus, separate logic for Main and Tie breaker path current

&

IN> 10 to 20%

PU Timer = 100 mS

TRIP ALL (Class A & BUS TRIP

IPh-B <2%

IPh-c <2%

OR

IPh-A >5%

IPh-B >5%

IPh-C >5%

OR

DO Timer 200 mS

Annunciation & SOE in SCADA / DCS

IPh-A <2%

LBB Initiation

OR

TRIP ALL (Class A & BUS TRIP

Breaker Flash over O/P

I>20% Timer 250 mS

&

Fig 6: Output action for LBB and Breaker flash over protection

Annexure-IV

Page 5 of 23

Annexure-VI

6 Adaptive Logic for Breaker Flash over protection of Generator.

(V) Solution

(b) Selectivity of Breaker Flash over for One and Half Breaker system arrangement of Bus.

The One and half breaker arrangement is mainly having advantage of redundant connectivity for feeders. As shown in fig-7, the Phase current used for Breaker flash over can be referred from Main or Tie breaker CTs. The breaker flash over may occur for Main or Tie breaker during synchronizing or after isolation from Grid. So both the paths must be

separately detected for flash arc current i.e. Main and Tie breaker. The action required after detection of flashover are different as detailed below.

(1) MAIN Breaker flash over Tripping of Generator in Class-A

to trip excitation immediately and stop prime mover for any rise in voltage due to residual magnetism.

Open all bus breaker to isolate the affected breaker from grid.

(2) TIE Breaker flash over. Tripping of Generator in Class-A

to trip excitation immediately and stop prime mover for any rise in voltage due to residual magnetism.

Trip Main breaker of Line side. Send Direct Trip Transfer signal to

isolate source from remote end.

The logic described for Current detection as Iph-A-B-C in earlier paragraphs equally used separately for Main and Tie breaker. The CT input for Main and Tie paths are indicated in fig-7.

Two separate logics should be built as conveniently in bay IEDs like, BCU or back up relay with separate set of actions as described above.

Please note that the neutral current here and elsewhere in document is indicated from GT neutral, whereas can also be used as Negative sequence current of Generator Phase connection also.

The setting values shown here are from experienced values for a 660 MW Generator, however can be considered on typical machine behavior and normal operation.

TIE

Fig 7: Current detection for selectivity for One and Half Breaker arrangement for breaker flash over protection.

Line Feeder

Y

D

Main-Line

Main-Gen

G

Iph-TIE

Iph-MAIN G

IN

Annexure-IV

Page 6 of 23

Annexure-VI

7 Adaptive Logic for Breaker Flash over protection of Generator.

(VI) CONCLUSION;

The breaker flash over phenomena is a very typical one to detect reliably and opt for action like isolation of bus and feeder at minimum possible time. Typical logic are offered by various manufacturer as indicated earlier, however use of reliable detection and output action is a part of scheme designing and adaption of philosophy.

Reliable detection and comprehensive logic is now very easy to be built in IEDs having numerous logical blocks, I/O configuration and even use of GOOSE signals for interlocking.

Breaker flash over protection must be used as a critical protection function particularly the locations like sea shore based or saline atmosphere surrounded installations, where chances of external flash over is higher. The lower flash arc current may also cause severe oscillation and asynchronous energisation may lead to damage to TG set or transformer.

Careful design should be carried out to handle flash over detection and isolation for one and Half breaker arrangement.

(VII) REFERENCES a. IEEE Guide for AC Generator

Protection: Std C37.102-1006, 4.7.1

b. Guide for Ac Generator Protection, ANSI/IEEEC 37.102-1995.

c. Application manual AREVA Micom P34x relay.

(VIII) Acknowledgement:

Author takes opportunity to express gratitude and special thanks to HOD of P&M Group of Adani Power Ltd., his guideline & knowledge, Adani Power Training & Research Institute, APL management for granting permission and inspiration to think and present this paper.

(IX) Author:

Sanjay U. Bhatt, working as DGM (Protection) at Adani Power Ltd, Ahmedabad, (Protection Automation & Metering Department), from January 2012.

B.E. (Electrical) -1993 from L.E. College Morvi , Gujarat (India).

Worked: o In G.S.F.C.-Jamnagar, as Ele.

Maintenance Engr. o In Govt. Polytechnic, as a lecturer on

clearing GPSC. o In GSECL, Gujarat as Junior Engineer

at Sikka Power station as Electrical Testing & Maintenance engineer and at SLDC during commissioning of SCADA and related system.

o As Deputy Engineer at GSECL corporate office as Testing engineer.

Annexure-IV

Page 7 of 23

Annexure-VI

External Flashover of Generator Circuit Breaker

in Coastal Power Plants having Air Insulated

Switchyard

Bishnu Prasanna Nanda and Pramod Kumar Saxena Adani Power Training and Research Institute, Ahmedabad, India

Email: {bp.nanda; pramod.saxena}@adani.com

Abstract—The breaker flashover can be either internal or

external. External flashover is mainly due to deposition on

the external surface of the contact housings. In case of

Power Stations in coastal areas, salt deposition takes place

because of saline atmospheric pollution. Breaker flashover is

an abnormal condition and may result in severe damage to

capital equipment like Generator and Generator

Transformer. Additionally it may also result in explosion of

Circuit Breakers which can damage nearby equipment in

Switchyard and put Substation personnel at risk.

Numerical relays used for Generator Protection have the

feature to detect breaker flashover condition and quickly

isolate the equipment. This paper describes such problems

at Mundra Thermal Power Plant in western coast of India

and also dwells upon the causes, protection philosophy,

preventive measures and recommendations.

Index Terms—flashover, an unintended electric arc,

creepage distance, shortest path between two conductive

parts measured along the surface of the insulation

I. INTRODUCTION

A. Brief Description of the Plant and the Problem

Adani Power Ltd is a Private Power Utility company in

India having currently installed capacity of 6600 MW in

three geographical locations and another 2640 MW is

under installation. Mundra Thermal Power Plant is

flagship plant of Adani Group having 4620 MW installed

capacity and located in west coast of Gujarat State, India.

The Power Station has 5 units of 660 MW and 4 units of

330 MW. Two units of 330 MW are connected to 220

KV and rest all units are connected to 400 KV grid.

The Power Plant is located 0.5 KM (Arial distance)

away from sea. Humidity remains 70% in day time and

80% in night. Both 220 KV and 400 KV Switchyard are

outdoor Air Insulated Switchyard (AIS) and the bus

arrangement is Double main and Transfer and one and

half breaker scheme respectively.

The Power Station has been experiencing failures of

string and suspension insulators because of salt coating

on external surface since 2009. The salt contamination in

Manuscript received May 10, 2013, revised September 8, 2013. This paper is property of APTRI and reproduction, use or disclosure

to third parties without express authority is strictly forbidden.

combination with dust because of proximity to sea lead to

decrease in withstand voltage and dry band formation

near cap & pin by high density of leakage current.

Erosion of porcelain insulators result due to increased

leakage current and finally it develops in to overall

flashover.

Tracking along the insulator surface and consequent

failures prompted the Power Station authorities to replace

all the porcelain insulators with Composite long rod

insulators and start hot line water washing on regular

basis. The ceramic insulators of equipment like CT, PT,

CB, Isolators etc. are part of equipment and hence can not

be replaced. However these insulators have been coated

with Room Temperature Vulcanizing (RTV) Silicone

Compound.

B. Incidence

On 30/06/2012, at about 04.22 Hrs, the 330 MW Unit-

4 was getting ready for synchronization with the grid

after a forced outage. The Turbine Generator (TG) set

was at 3000 rpm and the Generator isolator in switchyard

was in closed condition. As soon as the voltage was built

up to about 24 KV, external flashover took place across

the Y-Phase Generator Circuit Breaker contacts with

heavy sound and the insulator housing of the contact got

broken. The unit got tripped on actuation of Generator

Protection.

At the same time Local Breaker Backup (LBB)

Protection of 400 KV bus also operated and all the

breakers connected with the bus also got tripped.

II. OBSERVATIONS POST OCCURENCE

Photographs of the damage Breaker pole has been

placed below as Photograph-1 and Photograph-2.

Photograph-1: Damaged Breaker Pole

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Photograph-2: Damaged Breaker Pole

The Disturbance Recorder (DR) chart of Generator

placed below as Fig. 1 clearly showed flashover of Y-

Phase CB. The current measured was 3.21 kA (RMS) and

4.63 kA (Peak).

Figure 1. Generator disturbance recorder chart

From the above observation and seeing the physical

condition of the Circuit Breaker, it was concluded that the

flashover in Y-Pole was due to external contamination in

saline atmosphere. Since the machine was ready for

synchronization, one side of the breaker was having grid

voltage and other side voltage i.e. machine voltage was

varying with respect to the grid voltage. Under such

condition, breakdown voltage was reached across the

breaker pole and flashover took place externally.

Similar flashover incidence has also been experienced

by Mundra Thermal Power Station previously in Unit-3

and Unit-7.

III. CAUSE OF BREAKER FLASHOVER

Flashover may occur across Generator Breaker

terminals during synchronization while the breaker is

open due to:

External flashover due to contamination

Internal flashover due to low dielectric pressure

High level of humidity

Frequently, only one phase of the breaker flashes over

during synchronizing procedures. In such case-

Power system suffers an undesirable out-of-step

and single-phase synchronization

Extensive damage to generators and step-up

transformers.

During synchronization process, the out-of-phase

voltage angle between contacts changes from 0 to 360

degrees continuously. Voltage across the breaker contacts

reaches its maximum instantaneous value when the angle

difference between the voltages is 180 degrees as shown

in Fig. 2 below-.

Figure 2. Voltage across breaker contacts

The voltage across breaker contacts before

synchronization (considering connection with 400 KV

Grid) -

Line voltage = 400 KV

Phase voltage = (400 /√3) = 231 KV

Peak value of Phase voltage =√2 x 231 = 327 KV

During out of phase condition, i.e. (voltage vectors 180

degree apart), net voltage across breaker contacts = 462

KV (RMS) and 654 KV (Peak)

This voltage may cause external or internal flashover

depending upon the breaker condition.

IV. METHODS FOR FLASHOVER PROTECTION

From the power system point of view, a flashover is a

fault which is not a ground or a phase-to-phase fault, but

a condition that resembles one phase of a breaker closed,

with a residual current much lower than a phase-to-

ground fault. A flashover can lead to a power oscillation.

Multifunction Numerical Generator Protection relays

have the function to detect both inadvertent energisation

and also breaker flashover condition. However standard

breaker-failure protections effective at detecting flashover

failure require an external trip signal from another

protection device to initiate the breaker failure. Relying

on an external trip prolongs the failure until line,

generator, or transformer protection trips.

The current flow during single phase CB flashover has

been shown below in Fig. 3.

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Figure 3. Current in case of single phase CB flashover

Following parameters can be used as inputs for

detecting breaker flashover and design protection scheme

for the same-

Phase currents

Residual current

Voltages from one or both sides of the breaker,

Breaker status auxiliary contacts (52a or 52b )

Close-signal monitoring or timers

Once the flashover is detected, all the breakers in the

bus must be tripped, as in a conventional breaker-failure

scheme. Security considerations are very important to

avoid mal-operations.

A. Method-1

Based on residual-current measurement and a breaker

auxiliary contact [52a- Normally open (NO) or 52b-

Normally closed (NC)] supervision. Logic for triggering

Breaker Failure scheme is shown in Fig. 4 below.

Flashover is detected and the bus is cleared if there

is residual current and the breaker is open.

Require timer to eliminate mismatching in time of

simultaneous closing of three phases.

Figure 4. Logic for initiating breaker failure scheme

B. Method- 2

Time Limits and Close-Signal Monitoring to Detect

Flashover is shown in Fig. 5 below.

Figure 5. Logic for Detection of Breaker Flashover

In order to operate this logic requires-

Phase current greater than set value and no current

five cycles before the start of the scheme.

Breaker auxiliary contact open.

No closing signal to breaker at least six cycles

before the start.

Allows scheme operation only if latch conditions occur

in the first five cycles after current flows in the breaker.

No mal-operation where a breaker auxiliary signal is lost

during normal operation with the breaker closed and

residual or phase currents present.

Method I would trip for this condition in case of

external fault. Timer is used to confirm the flashover

condition. The timer resets once current falls set value or

close signal appears or 52a indicates a closed indication.

Unbalanced currents associated with breaker head

flashover will generally cause the generator negative-

sequence relay to operate. This will initiate tripping of the

generator breaker(s), shutting down the generator and

providing the Breaker Failure Initiation (BFI) signal. The

Breaker Failure Logic will be initiated only if the breaker

failure current detectors are set with sufficient sensitivity

to detect the flashover current.

In case the current detectors are set higher than the

flashover current and breaker failure is not initiated, the

result may be catastrophic failure of the generator. The

key consideration for setting the breaker failure current

detector is to set it below the level of the current expected

for breaker-pole flashovers.

One approach used to speed the detection of a breaker

flashover is to modify the breaker failure scheme as

shown in Fig-6. An instantaneous overcurrent relay (50N)

is connected in the neutral of the generator step-up

transformer and is set to respond to an Extra High

Voltage (EHV) breaker pole flashover current. The relay

output is supervised by the generator breaker “52B” NC

contact providing an additional start to the breaker failure

scheme. When the generator breaker is open and one or

two poles of the breaker flash over, the resulting

transformer neutral current is detected by the 50N relay

without the delay that would be associated with a

negative sequence relay. The current detectors (CD)

associated with the generator breaker scheme must be set

with sufficient sensitivity to detect this flashover

condition.

Figure 6. Speedy detection of Breaker Flashover

V. PROTECTION PROVIDED IN MUNDRA UNITS FOR

BREAKER FLASHOVER

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A. Phase 1&2 Units

In Phase-1&2 the relay used for Generator Protection

is P344 of AREVA make. In this relay, detection of

Breaker flashover condition is by a neutral current

measuring element. The relay standby earth fault

protection element has been connected to measure the

transformer HV earth fault current and provide the

breaker flashover protection, via suitable scheme logic.

B. Phase 3&4 Units

In Phase-3 & 4, the Generator Protection Relay used is

RCS 985B of Nanjing NARI Relays, China make. In this

relay single phase and two phases flashover has been

considered but three-phase flashover is ignored.

Criterion of circuit breaker flashover:

Position contacts of three phases of circuit breaker

are open

Negative sequence current is higher than setting

Excitation has been applied to generator, and

generator voltage is higher than setting.

Operation of this protection will shut off excitation and

activate BFI Protection.

VI. PREVENTIVE MEASURES TO AVOID FLASHOVER

The saline pollution environment is prevalent in all

Coastal Power Stations. The degree of pollution may be

different at different places.

Probability of breaker internal flashover is highest in

SF6 type of breaker. However since external flashover is

due to contamination, it can take place in any type of

breaker. Following preventive measures need to be taken

to avoid external flashover:

Line isolators should be closed just prior to

voltage build-up and when machine is ready for

synchronization.

Generator Breakers used in coastal areas should be

designed with higher creepage distance (about 35

mm/ KV) or else use creep extenders.

Regular cleaning of the insulator (Hot line

washing with DM water) to avoid salt deposition.

Avoid synchronization when humidity is high.

In Mundra TPP, the activity listed in 1 & 4 of above

list is being done regularly. Additionally, HVCE (High

Voltage Creepage Extenders) are being procured for use.

High Voltage Wraparound Creepage Extenders are

designed for use in highly contaminated environments.

The wrap around type cold applied variant is retained in

place on the collar of the existing porcelain disc with the

help of pressure sensitive mastic. Typically application of

one extends nominal creepage distance of the existing

insulator by 100 mm. It is also quite imperative to note

that once 20% of the creepage is added with the help of

extender, pollution withstand ability of the original

insulator without creating electrical flashover enhances

by more than double. The extenders are designed to be

resistant to conventional spray washing techniques and

will withstand most normal handling, abuse, and extreme

weather conditions. Photograph-3 below shows a typical

bushing fitted with Wraparound Creepage extender.

Photograph-3: HV Wraparound Creepage Extender

VII. CONCLUSION

Generator tripping on account of Breaker Flashover

can be very disruptive and costly to the Power Utility.

Determining the cause of the tripping and assessing

equipment damage can take lot of time and consequent

delay in returning to normal operations.

Following are the recommendations:

Presently the cost of Gas Insulated Switchgear

(GIS) has come down and indoor GIS can be

considered. The author’s strongly recommended to

go for GIS in place of AIS in Coastal Power

Stations. The capital cost of Switchyard shall be

about 50% high, but the operating cost shall very

less and payback period is about 5 years.

It is critical to have good sequence-of-events and

oscillographic data to review protective relay

performance, assess fault levels and clear the

machine of any damage. Instead of relying on fault

recording feature of Numerical relays, dedicated

DR should be installed in all large capacity

Generators.

A dedicated breaker-flashover scheme is a must

for breakers used to synchronize Generators.

ACKNOWLEDGEMENT

The authors wish to thank the management of Adani

Power Ltd for granting permission to participate in this

Conference and present this paper.

The authors also thank the personnel of Adani Power

Training and Research Institute (APTRI) for their support

and help in submission of paper and registration.

REFERENCES

[1] Guide for Ac Generator Protection, ANSI/IEEEC 37.102-1995. [2] IEEE Tutorial on The Protection of Synchronous Generators,

IEEE 95TP102.

[3] AC High-Voltage Circuit Breakers Rated on A Symmetrical Current Basis—Preferred Ratings and Related Required

Capabilities, IEEE C37.06-1987. [4] IEEE Standard for AC High-Voltage Generator Circuit Breakers

Rated on A Symmetrical Current, IEEE C37.013-1993.

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[5] IEEE Standard Test Procedure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis, IEEE C37.09-

1979.

[6] IEEE Guide for AC Generator Protection, IEEE C37.102-1987. [7] Evaluation of Methods for Breaker Flashover Protection, Ramón

Sandoval Comisión Federal de Electricidad Sinaloa, México.

Bishnu Prasanna Nanda has about 32 years’ experience in Indian Power sector and has worked

in both Public and Private Power utilities. He has

done B.Tech in Electrical Engg from National Institute of Technology, Raurkela, Odisha, India

in 1981. He has also done Advanced Diploma in Management from IGNOU, New Delhi. He has

been certified as Energy Auditor by Bureau of

Energy Efficiency, New Delhi, India. During his career spanning 32 years, he worked with NTPC Ltd for 27 years in various Project sites in

Operation & Maintenance wing. Since 2008, he is with Adani Group

and presently working as Vice President (Engineering).

Pramod Kumar Saxena has more than 28 years’

experience in Indian Power sector and has

worked in both Public and Private Power utilities. He has done B.E in Electrical Engg from

Government Engineering College Rewa Madhya Pradesh, India in 1984. During his career

spanning 28 years, he worked with NTPC Ltd for

20 years in various Project sites in Operation & Maintenance wing. Since 2008, he is with Adani

Group. Up to 2012 he worked in projects and commissioned 5 units of 660 MW at Mundra. Presently he is working as General Manager

(O&M) at Mundra TPP.

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PRACTICAL INTERLOCK LOGICS TO PREVENT UNDESIRED CIRCUIT BREAKER CLOSING, ISOLATOR OPENING & CHARGING OF BAY

IN SUB STATION USING IEDS

Sanjay U Bhatt, Protection, Automation and Metering Department

Adani Power Ltd, Ahmedabad E-mail: [email protected]

ABSTRACT Un desired charging of a bay / equipment when is ready to charge or immediately after getting isolated, due to accidental closing of circuit breaker or breaker flash over may result in severe undefined damage / loss to equipment / system stability / human loss, as well financial burden due to huge repairing cost and outage period till normalcy.

This paper describes practical interlock logics using IEDs for (1) controlling DC negative source to circuit breaker closing circuit and (2) Auto opening of Isolators after opening of circuit breaker.

KEYWORDS Circuit Breaker closing circuit logic, DC negative source breaking for CB closing, Isolator Auto opening logic, safety interlock for CB and isolator.

1. INTRODUCTION The essential element of a protection & control circuit design is to have inclusion of all engineering aspects for control, protection, monitoring & measurement having considerations for technical & operational limitations and capabilities of equipments, system and switchgear, operation possibilities & flexibilities with safety interlocking.

Fig. 1 is a typical such circuit conventionally used for a Circuit Breaker closing purpose.

Fig 1- Typical Closing circuit of a circuit

Accidental shorting of DC+ve to close CB

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The safety interlocking involves design of circuit in a controlled manner, by which ultimately actuates the operating mechanism of relevant circuit breaker / isolators / contactors / solenoids etc. for bridging primary connections to charge or operate the equipment. CASE-I In case of a circuit breaker for closing circuit interlock, the auxiliary supply (DC +ve or Phase) is extended from source to actuating point connection of closing coil of a circuit breaker through various permissive contacts ensuring healthy operating conditions, CB readiness, and absence of any abnormalities. The cables are routed through all relevant location of interlock contacts. DC –ve or Neutral is directly connected to other end of closing coil. A typical circuit is shown at Fig. 1.

The opening of isolator on load is also such kind of operation due to similar reasons indicated above.

CASE-II

In addition to the undue closing of circuit breaker, the undesired energizing of equipment (Transformer, Generator, Line etc.) may also happen in case of breaker flash over (internal or external) , particularly in case of Generator or two charged line from different sources, when going to synchronize or after isolated from grid. This is due to external insulation failure or arcing within breaker chamber, causing out of phase connection of two vector (peak to peak twice magnitude) causing severe oscillation and damage to equipment. The detection of breaker flash over reliably and isolation is still a serious concern especially in case of one and half breaker arrangement. Fig.2 shows a typical bay arrangement for a Generator with possible peak to peak voltage vector from Grid and Generator causing flash over. .

An automatic and comprehensive logic which can detect successful opening of breaker and initiate command to open the outgoing circuit isolator with flexibility of closing operation will be very useful to be secure against such wrong energisation of equipments

Fig 2- Typical One and Half CB arrangement possible breaker flash over due to peak to peak voltage across CB open contacts Breaker

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2 A CASE STUDY FOR GENERATOR BREAKER RECLOSING AFTER TRIPPING.

Recently at one of the large power plant the Generator Transformer Bushing of a phase failed which led to tripping of unit on operation of overall differential protection with tripping of both Main & Tie breaker. Due to heavy flash over and burning of insulation & oil, there was heavy fire and hot oil spread in nearby MK box & cable trench. This led to damage of all cables as shown in the pictures. After @10 Minutes the Main breaker got closed due to shorting of cable carrying DC+ve and return for closing. However the tripping command was persisting on operation of lockout relay hence tripping of breaker was taking place immediately on closing this sequence repeated multiple times and then stopped on blowing of main DC fuse.

Due to very short time closing, opening of B phase HV bushing of GT and residual rolling of turbine, nothing further damaged occurred.

Fig-3, indicates the control cables route for CB closing from switchyard kiosk to Generator Relay Panel and Synchronizer panel located at Main C/R. The cable trench route is passing near GT area where fire took place.

The detailed closing control circuit is shown at Fig-4.

It is therefore must to review the conventional closing circuit scheme for breaker & Isolator and cabling practices.

Fig 3- Showing location of Bay Kiosk, CB, GT and Main C/R with route of control cable.

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Due to fire cable damaged and shorted core to complete the closing circuit path for DC Positive return to Circuit Breaker Closing circuit.

Generator Relay Panel interlock for closing circuit

Synchronizing interlock for closing circuit and closing command from Main Control Room

CB cubicle at Switchyard

Control cables in cable trench from Switchyard to Main C/R

Interlocks

Figure-4- A Generator Breaker Closing circuit, event of closing control cable shorted resulting in undesired closing of circuit breaker Annexure-IV

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3. ISSUES WITH CONVENTIONAL CIRCUIT BREAKER CLOSING & ISOLATOR OPEN CIRCUIT.

Please refer case study mentioned earlier, where the breaker closing circuit philosophy used is conventional as described previously. The scheme is simple and being used everywhere.

Pl. refer Fig.1, and case study occurrence, it is seen that extension of DC +ve supply to closing coil terminal is the only deciding factor for closing operation of breaker and also opening sequence of isolator . Any undue extension of DC+ve to operating coil may lead to undesired operation of equipment. The undue extension of DC+ve to closing circuit/isolator opening circuit may happen due to (1) shorting of control cable carrying DC+ve and return path after permissive and command towards CB/Isolator, and (2) Simultaneous grounding of DC+ve system and terminal connected to CB closing / Isolator Open circuit. The sample case for CB are mentioned in following sections which will also apply to Isolator open circuit with due modifications.

4. SOLUTION TO BREAKER CLOSING DUE TO UNDESIRED SHORTING OF DC+VE.

The mishap due to above indicated DC+ve shorting can be avoided by breaking DC-ve immediately after closing CB and the same can be made through just before closing CB, command through SCADA/IED.

The simple solution is to switch OFF the closing supply immediately after closing CB and make ON when required to close. The same can be made by breaking DC +ve as well with the method described here. However this may involve addition of circuits and contacts for +ve at DC source also, with simultaneous operation of contacts on both sides, adding more complexity and online monitoring of closing circuit also is not possible. So for our purpose DC-ve breaking scheme is sufficient.

.

Existing Closing Circuit 

Close Guard I/P 

Fig. 5a- Closing circuit DC Negative breaking with CMR operated from Logical operation of IED / circuit. CMR placed at Breaker MK box.

Fig. 5b- Closing circuit DC Negative breaking with Output of IED / Logical circuit scheme placed at Control panel

Digital / Analogue Interlock I/O 

Digital / Analogue Interlock I/O 

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Fig. 5a and 5b above indicate the methods of breaking DC-ve using logical operation performed from numerical IEDs or such circuit from conventional relay, contactor, timers etc.

A simple way of breaking DC-ve is to route it from Master trip relay contacts where DC+ve for closing permissive is also routed.

However in case of manual opening or isolation Master Trip relay may not operate or can be reset after tripping for further interlocks and operations in a Generating Station. So it is also not covering complete risk.

In method 5a the CMR (Contact Multiplier Relay) placed in CB MK box is used to isolate the DC –ve. The CMR is operated by a separate DC/AC source from IED/ Logical device. As shown the CMR energizing supply is also wired from two separate contacts from IED at C&R panel. This will ensure complete secured operation of CMR even in case of the cable damage for CMR.

In method 5b the DC-ve is routed through contacts of IEDs/Device placed at Kiosk in Switchyard interfaced with SCADA.

Method 5a is the most appropriate one for all cases due to secured operation of CMR placed very near to CB closing circuit in MK box.

The CMR method should be used where there is no S/Y Kiosk near to CB and C&R panels are located at Main C/R directly connected with CB for control.

All above method should ensure secure operation with flexibility to operator and monitoring feedback. It should also supervise the shorting of cable or undue extension of DC+ve in closing circuit by guarding method.

5. LOGIC FOR BREAKING DC-VE USING IEDs & SCADA.

A practical logic using IEDs and SCADA interface implemented at the power station where the undesired closing of Generator Breaker happened as referred in case study is shown here at Fig. 6a and 6b.

Explanation of the logic:

Please refer Fig 6a, where a concept circuit is shown for placing of IED /CMR contact in the Negative terminal of closing coil (CC). The Guard input from DC+ve circuit is connected before CB auxiliary switch contact which is closed when breaker is OPEN or immediately after closing contact circuit. The guard input turns in high state when Close command is extended or any undue positive is extended in close circuit.

Please refer Fig 6b, the main logic part which can be built in IED (Relay/Bay Control Unit BCU / RTU having required logical blocks with IEC61850 accepting GOOSE signal and hard wired Binary I/O signal from scheme wiring and interfacing with local SCADA. This is generally available now with all IEDs installed in a switchyard.

The logic uses RS Flip Flop block having reset priority for latching output OPEN / CLOSE. The Flip Flop get reset and breaking DC-ve when

Circuit Breaker is closed successfully. Lock out / Master trip relay operated. Circuit Breaker Pole Discrepancy Relay

(PDR) operated. Circuit Breaker closeing permissive interlock

NOT OK. Negative Bypass command from Switchyard

SCADA is given for Manual Bypass purpose.

All above condition will cause Flip Flop to reset and opening of contact to break DC-ve.

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52b

CC

Various external interlocks / commands

Breaker MK / Control Box

IED/ CMR Contact

DC ‐ve

DC +ve

CB CLOSE (Except Line Bay)

CB-PDR Operated

Lock out relay Operated

RESET

SET

OUT

+ve Guard input High

‘CLOSE circuit through command’ (Pulse) from OWS

RS Flip-flop

IED Contacts to 

operate CMR or to 

DC‐ve circuit of CB 

as per scheme 

adopted. 

Guard BI of BCU / IED

200 ms 

NOTE: The logic can be built in IED (Relay/Bay Control Unit BCU / RTU having required logical blocks with

IEC61850 accepting GOOSE signal and hard wired Binary I/O signal from scheme wiring and interfacing with local SCADA. This is generally available now with all IEDs installed in a switchyard.

Necessary wiring / GOOSE configuration should be worked out for I/O as per logic. ‘The Close circuit through command’ from OWS (Operator Work Station of SCADA) to extend DC-ve for

manual close should be initiated before closing of breaker so that –ve circuit to closing coil will be extended. In case of any unwanted DC +ve extension in closing circuit will be monitored by Guard circuit and will not

allow the flip flop to set to extend DC –ve to closing coil. Which is monitored in SCADA also. The Guard timing is considered as 200 mS allowing closing of breaker normally. The above circuit can also be used for isolator control circuit with modification in input logic and other

interlocks.

Manual Reset (Pulse) from OWS

CB closing permissive OK

Interlock status feedback to SCADA / OWS

Fig 6b - Logic for DC-ve breaking for Circuit Breaker Closing circuit

Fig-6a- Concept Circuit for Breaker Closing circuit

Breaker Aux. contact

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The Flip Flop will be set to drive BO to extend DC-ve under following condition.

Though manual command from OWS (SCADA) when it is really required to close breaker, if the DC Guard input is NOT High more than 200 mSec.

Immediately after closing of CB the Flip Flop will get reset breaking DC-ve till a manual intervention is made which should be done just before closing the breaker. In case of line after closing of breaker to allow Auto Reclosure operation DC-ve is not being broken, however except in case of three phase tripping.

Further it is also important to have wire cores for DC +ve source of closing circuit going to external wiring and return from CB MK should be in different cable and not in same cable.

Above logic has been implemented and proven well working taking care for all possible abnormalities. The same can also be used to take care for undue opening of Isolator with some modification of logic such as the phase and neutral (OR DC +ve and –ve) will be extended simultaneous when any open command generated from valid open sequence and other interlocks.

Snap of logic and control built in SCADA database is mentioned as under for a Generator Circuit Breaker.

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6. LOGIC FOR AUTOMATIC OPENING

OF ISOLATOR AFTER TRIPPING OF CIRCUIT BREAKER.

It is well known that an Isolator is OFF Load and Circuit Breaker is ON Load circuit breaking equipments. Opening of an Isolator on load will lead to a severe damage to equipment and human also. Due to this reason to avoid accidental opening of isolator a routine practice is being adopted for an isolator, to switch OFF isolator Driving Motor supply after closing electrically or manually. However in case of ABCB earlier, due to risk of getting closing of circuit Breaker on low air pressure automatic opening of isolators on immediate opening of CB was used using hard wired CB status based logic. Now days all isolators are remotely operated from SCADA and also with concept of unmanned S/S the Isolators are kept ready to operate with all auxiliary sources in service. With this arrangement it is must for isolator to have DC-ve and also automatic opening of isolator breaking logic schemes.

Please refer Section 2 Case-II and case study of occurrence, the reclosing of Circuit Breaker due to any reason or flash over subsequent to opening of breaker or before synchronizing will defiantly damage the equipment connected. In the referred case, the immediate opening of circuit (Line) isolator on opening of CB would have saved the impact on Transformer and Generator, if so designed in the scheme. The manual opening of isolator immediately after tripping of CB is also not expected due to human action.

The logic implemented at Sub station referred earlier is mentioned at Fig 7 & 8 using Bay Control Unit, GOOSE signal for status / Analogue signal over IEC 61850.

The output of Auto OPEN Logic is configured with same output of the existing logic for OOPEN sequence of isolator taking status and feedback as per logic.

Explanation of the logic:

Please refer Fig. 8, the Auto Open sequence will be initiated after proposed time delay of 5 sec, when (i) Under current relay picks up AND (ii) Main Breaker is not CLOSED AND (iii) TIE Breaker is not CLOSED AND (iv) Isolator closed status is high. For secure operation the interlock of load current and breaker status has been incorporated. The Auto open sequence will be automatically latched for next operation when (1) Under current relay resets OR (ii) Main Breaker CLOSED OR (iii) Tie Breaker CLOSED, after a proposed time delay of 5 sec. The next closing sequence will be initiated by Manual command from SCADA OWS for SET command to the RS Flip-Flop, and when it is set will allow manual CLOSE sequence to operate making the operation more secure and enhancing the CLOSE logic also.

Again after opening of breaker and sensing of under-current will allow Auto opening of isolator as per logic.

The implemented logic screen snap is also indicated at Fig-9.

Existing CLOSE sequence

Existing OPEN sequence 

AUTO OPEN Logic 

BCU Output for Isolator OPEN & CLOSE 

SCADA interface 

Annexure-IV

Page 21 of 23

Annexure-VI

Fig 8 - Logic for Auto open of Isolator after opening of Circuit Breaker 

&

I<1 Under Current 

Main Breaker CLOSE 

TIE Breaker CLOSE 

Isolator CLOSE status 

Manual SET  

(Pulse) from OWS 

Timer  OPEN 

Command 

to Isolator 

  RESET

OUT

O

R

SET

To Isolator CLOSE logic interlock 

to ensure SET condition of Auto 

Open sequence 

& Existing LOGIC for 

Isolator CLOSE command 

CLOSEE 

Command to 

Isolator

T 

5 S

NOTE: Manual SET command from OWS SCADA should be SET before Closing of Isolator. The Logic is built in BCU and connected with existing OPEN command of isolator. Manual Set command latch O/P from flip flop is interlocked with Existing Logic for Isolator Closing Required modification & configuration of relevant relay for under current setting and Logic should be worked out. Timing for Auto Open Isolator may be set at 5 second after opening of CB.

Fig 9 – Implemented Logic for Auto open of Isolator after opening of Circuit Breaker 

Annexure-IV

Page 22 of 23

Annexure-VI

7. CONCLUSION

The described engineering practice should be implemented as a standard scheme for operation of Circuit Breaker and Isolators looking to secure operation of primary switching.

Because numbers of incidences are being occurred on account of damaged cables or DC- grounding or mal-operation even during fault finding or testing of control wiring. The use of latest technology or equipment without reliable operating mechanism is waiting for a disaster always.

Availability of Numerical technological IEDs and GOOSE signals over IEC61850 protocol with SCADA has made the task very easy and secure.

(1) Circuit Breaker Closing circuit should be equipped with DC-ve breaking as near as possible to Closing Coil with Contact Multiplying relay / IED (Relay) contact with secured logic, control and monitoring facility in SCADA.

(2) Isolator OPEN circuit should also be equipped with similar above scheme logic indicated at (1).

(3) Circuit (Line) Isolator should be automatically opened immediately after tripping /Opening of CB/s. The logic should be secured enough to ensure complete OFF Loading of circuit and also with no confliction with CLOSE sequence operation.

(4) The control cables carrying DC-ve from CB / Isolator and to IED/Relay at C&R panel should be in different cable, preferably separate route to avoid any possibility of malfunction of the above discussed circuit itself.

(5) All the input / output and logical status should be configured in event of IED and SCADA for future analysis on event of occurrence.

(6) The new specification for C&R panel and scheme should be included with above said requirements.

REFERENCES:

(1) Various schemes drawing for different substations.

(2) AREVA make application manuals on BCU MICOM C264 /EN/AP/ C30, PACIS Operation Interface for Automation and other IEDs

(3) ABB make application manuals on 670 series IEDs.

AUTHOR:

.

.

.

Sanjay U. Bhatt, working as DGM (Protection) at Adani Power Ltd, Ahmedabad, (Protection Automation & Metering Department), from January 2012.

B.E. (Electrical) -1993 from L.E. College Morvi , Gujarat (India). Worked: In G.S.F.C.-Jamnagar, as Ele. Maintenance Engr. In Govt. Polytechnic, as a lecturer on clearing GPSC. In GSECL as Junior Engineer at Sikka Power station as Electrical Testing & Maintenance engineer and at SLDC during commissioning of SCADA and related system. As Deputy Engineer at GSECL corporate office as Testing engineer.

Annexure-IV

Page 23 of 23

Annexure-VI

Latest status of implementation of recommendations of PSAG-3 for

the Gird incident occurred at SGS on 18.08.2013

S.N.

Recommendations

KPCL’s Compliances

a Disturbance Recorder facility LOA issued to M/s Alstom T&D India Ltd., Chennai for Supply & Erection of Disturbance Recorder & GPS on 26.06.2015. During Fire accident on 18.2.2016 at SGS, all the equipment and panels placed in control room - control, relay, protection, metering panels, cable duct, cables, air conditioning system, fire detection system, etc., have been burnt completely. Hence, Re-engineering work to suit the upcoming DCS system at site, is in progress.

b Providing GPS (Time synchronization) facility

c To replace both bus sectionalizing BOCBs with new circuit breakers

LOA issued on 12.12.2014 to M/s ABB India Ltd., Bangalore. Supply and Erection of both the Breakers completed. Commissioning will be taken up along with commissioning of Sectionaliser panels from new Bay Control Rooms.

Annexure-V

Annexure-VI

S.N Commitee observations KPCL Compliance

5

KPCL shall take action to arrange for GPS time

synchronisation of all EL's and provide DR for all

lines.

Completed.

6KPCL shall take action for retrofitting of all old

electromagnetic relays with numerical relays.

Retrofitting electromechanical relays with Numerical version relays completed for

all 400kV lines.

Work Order placed on 26.06.2015 for retrofitting of relays for all 220kV lines at

RTPS. Commissiong of relays completed for Lines: Lingasugur -1,2 &3, raichur-1 &2,

Sedam 1 &2. Erection is in progress for Shahpur 1 & 2 Lines.

Obtained the Budgetary offer for retrofitting the electromechanical relays of

existing bus bar protection with numerical version and is under process.

12Recommondations of protection Audit conducted

on 02.11.2012 shall be carried out.

All Recommondations of protection Audit are being implemented in both 220kV &

400kV RTPS station except that the erection of Numerical relays is in progress for

Shahpur 1 & 2 Lines . The latest status of activities in phase-1 & phase-2 are

updated on bimonthly basis.

COMPLIANCES FOR THE RECOMMENDATIONS OF SPECIAL PROTECTION ANALYSIS GROUP COMMITTEE (SPAG-6) DURING THEIR VISIT TO RTPS

ON 05.02.2014.

Annexure-VIAnnexure-VI

1

The PSAG-10 members recommended to replace the Main I (Q21 static

Quadramho relay -SHPM 101) distance protection relays with Numerical relays

having DR and EL features.

LOA’s issued on 08.10.2015. Inspection of relays completed

and received at site. DI issued for all balance materials

except furnitures.

2The PSAG group also advised KPCL to test the Main II Relay (PZ1000

numerical relay) at the earliest .

Completed.

3

The PSAG group recommended to have a uniform Zone II time settings as

agreed in the Tripartite meeting of KPCL, KPTCL and Kaiga (NPCIL) held during

11th& 12th of December, 2013) in the Kaiga – Kali Complex.

Completed.

4

The Resistive reach of distance protection relay of Kadra – Kodasalli (both

ends), Kadra – Karwar I, Kadra – Karwar II (Kadra end), Kodasalli – Nagjheri I,

Kodasalli – Nagjheri II (both ends) lines to be increased so as to operate on high

resistance faults within the permissible limits . Since the present settings are

prone to under reach and initiating unwanted tripping at the their locations,

PSAG has recommended to suitably increase the resistive reach of all the lines.

PSAG advised KPCL to revise the settings at the earliest.

Completed.

5

PSAG recommended to make the carrier aided protection functional for 220kV

Kadra-Kodasalli, 220kV Kadra-Kaiga and 220kV Kodasalli-Kaiga lines. In

addition, since most of the faults are seen as high resistance fault, PSAG

suggested to revise the existing PUR to POR scheme for all the lines at Kali

complex.

LOA’s issued on 08.10.2015. Inspection of relays completed

and received at site. DI issued for all balance materials

except furnitures.

6

The PSAG group noted that most of the faults were in the ‘B’ Phase (of RYB) to

ground faults. The group observed that it may be due to thick vegetation below

Kadra – Kodasalli, Kodasalli - Kaiga line, Kadra – Kaiga line. Hence the PSAG

group members advised to have regular thorough line patrolling and clearing the

corridor (i.e. Right Of Way).

To be implemented by KPTCL

Compliance to recommendations of Meeting of Protection system Analysis Group (PSAG-10) at Kadra, Kodasalli and

Kaiga held on 12th & 13th November 2014 for discussing the Grid Disturbances occurred on 26.09.2014 and 05.10.2014

Sl. No. Recommendations KPCL Compliances

Page 1 of 2

Annexure-VII

Annexure-VI

Sl. No. Recommendations KPCL Compliances

7

PSAG had recommended to have a uniform setting for the backup earth fault

protection (67N) provided through distance relay (i.e PZ1000) and separate

back up earth fault relay (CDD21 of English Electric, electro mechanical)

immediately.

Completed.

8The PSAG group advised to disable the phase over current protection in

distance relays (i.e PZ1000 of CSPC make) immediatelyCompleted.

9

KPCL informed that installation of GPS for time synchronization of all relays and

other protection devices is under process. KPCL is requested to expedite the

same.

LOA’s issued on 08.10.2015. Inspection of relays completed

and received at site. DI issued for all balance materials

except furnitures.

10

It is suggested to check timings (opening and closing) on Kadra line CB test at

Kodasalli station periodically and the record of checking to be maintained in the

substation

Completed.

11

It was observed that Kodasalli – Nagjheri I & II lines were kept open at Nagjheri

end on 26.09.2014, 5.10.2014 & 14.10.2014 during bus dead conditions at

Kodasalli station. KPTCL (SLDC) is requested to clarify /review the issue

To be implemented by KPTCL/SLDC

12The DR and EL data of the line/unit tripping shall be made available for analysis

at station level / SLDC /SRLDC/SRPC level.Noted

Page 2 of 2

Annexure-VII

Annexure-VI

S.N Commitee observations KPCL Compliance

1 To check the REF scheme during next shut down

for GT of Unit -7 at RTPS

Completed.

2 To take up with OEM and check the configuration

for auto reclose in relay at RTPS end as block for

auto reclose should not initiate with fuse fail On/

Start

The PSL, Event, DR & settings files extracted from the relay have

been sent to OEM for checking & reviewing. Settings received &

have been loaded in to the relay.

3 To simulate the sequence of event for relays

which trigger Class-B master relay and also check

up the pick-up voltage of Class-B Master trip relay

of Unit-5 at RTPS.

The same was checked and found to be order.

COMPLIANCES FOR THE RECOMMENDATIONS OF SPECIAL PROTECTION ANALYSIS GROUP COMMITTEE (PSAG- 13) DURING

THEIR VISIT TO RTPS ON 23.04.2015

Annexure-VIII

Annexure-VI

Mee

ting

No /

Inde

x

Details of

Event

Date Reason PCSC Recommendations Utility

Responsible

for

implementatio

n

Status of Recommendations

as on

Remark

s

Pending Implementation of PCSC Recommendations (30th to 53rd)

Karnataka

Annexure-IX

Page 1 of 12

Annexure-VI

Pending Mail recieved on 28-05-2015:

1. e- Tender folated for the retrofit of existing static relays with

Numerical version for lines M.nagar,M.bad,ICT-1 & 2 -Technical Bid &

Price bid opened . Bid evaluation and approval to place P.O. is in

progress.

2. Retrofit of existing bus bar (CAG-34) with numerical version -

Budgetetory offers obtained and is in process.

3. Order placed on M/s Siemens to replace relays. The work will be

Completed by May - 2015.

Mail recieved on 07-07-2015:

1. Retrofit of existing static relays with Numerical version for lines

M.nagar, M.bad and ICT- 1 & 2 -- Inspection of the Numerical relays at

M/s Siemens works completed on 11-06-2015 and Dispatch clearance has

been issued. Materials received.

2. Retrofit of existing bus bar (CAG-34) with numerical version –

Budgetary offers obtained and is under process.

Mail recieved on 07-09-2015:

1. Replacement of Old electromagnetic relays with Numerical relays has

been completed for RTPS-BTPS line & commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with

numerical relays.

The retrofitting of electromechanical relays with Numerical version for

ICT-1, ICT-2 and Munirabad line has been completed.

Retrofitting work for Mehaboobnagar line is pending. Awaiting for line

shutdown.

2. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd.

Chennai for retrofitting of relays for all 220kV lines at RTPS.

3. Retrofit of existing bus bar(CAG-34) with numerical version–

Budgetary offers obtained and is under process.

Mail recieved on 21-10-2015 and 23-11-2015:

1) Replacement of Old electromagnetic relays with Numerical relays has

been completed for RTPS-BTPS line & commissioned on 18.03.2014.

Raichur-PG1 & Raichur-PG2 lines have already retrofitted with

numerical relays.

The retrofitting of electromechanical relays with Numerical version for

the following lines/ICTs have been completed/commissioned as follows:

a) ICT-2 –Commissioned on 01-08-2015

b) ICT-1 ---Commissioned on 08-08-2015

c) Munirabad line--- Commissioned on 16-08-2015.

d) Mehaboobnagar line-- Commissioned on 09-09-2015.

2. Job order placed on 26.06.2015 on M/s Alstom T&D India Ltd.

Chennai for retrofitting of relays for all 220kV lines at RTPS.

3. Retrofit of existing bus bar(CAG-34) with numerical version–

Budgetary offers obtained and is under process.

RTPS

Tripping

incidents and

the Spl

meeting held

at RTPS on

13th and 14th

March 2014

30/I/

A

KPCLThe PCSC forum recommended for replacement of existing

electromechanical relays with Numerical relays. Spl meeting held at RTPS on 13

th and 14

th

March 2014

Mar-14

Annexure-IX

Page 2 of 12

Annexure-VI

Mail recieved on 28-05-2015:

1) e-NIT floated on 28.07.2014 for procurement of Numerical distance

relays & GPS. As there is change in scope of work and quantity of relays

by more than 25%, which is not permitted as per KTPP act. Hence, tender

cancelled and refloated on 05.05.2015 with revised scope of work and

revised PQR.

2. However, as per the recommendations of PSAG, Relays were

temporarily rearranged, replaced and wired up. testing & commissioning

shall be completed with the assistance of KPTCL.

Mail recieved on 07-07-2015:

1. Cover -1 of the bid is scheduled for open eing on 25.06.2015.

2. As per the recommendations of PSAG, Relays were temporarily

rearranged. testing & commissioning completed with the assistance of

KPTCL.

Mail recieved on 07-09-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed.

Obtaining of Administration approval to place P.O is in progress.

However, as per therecommendationsof PSAG-10, Relays

weretemporarilyrearranged.Testing & commissioning completed with the

assistanceofKPTCL.

Mail recieved on 21-10-2015:

NIT floated on 5.5.15 through e-portal. Bid evaluation completed. LOA's

issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Mail recieved on 23-11-2015:

LOA's issued to M/s Schneider Electric Infrastructure Ltd. on 08.10.2015.

Engineering work is in progress.

Status informed during Special Meeting held on 03.06.2016:

LOA’s issued to M/s Schneider on 08.10.2015. Inspection of relays

completed and received at site. DI issued for all balance materials except

furnitures.

KPCL1. The PCSC forum requested KPCL to speed up the installation

of Numerical Distance Protection relay in Kadra –Kaiga and

Kodasalli –Kaiga.

2. The PCSC forum requested KPCL to submit the implementation

status of PSAG-10 recommendations within a week’s time.

A fault had occurred in 220 kV Kadra and

Kodasalli. As A result, de-energization of

220kV bus occurred at Kadra and

Kodasalli.

13-11-2014

at 19:31hrs

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

1.Existing Back up relays will be replaced by numerical type distance

relays.Procurement is in tendering stage. Remaining observations were

attended.

KPTCL Mail recieved on 23-01-2016:

Existing back up relays will be replaced by Main-2 protection. LOI issued

M/s Alstom for taking up the works.Remaining observations were

attended.

KPTCL Mail Recieved dated 25-05-2016:

Under the Scope of R&U. The work will be taken up by M/s Alstom

shortly.

KPTCL1. PCSC forum recommended KPTCL to replace the old static

distance protection relays with numerical relays.

2. PCSC forum also requested KPTCL to provide a broken

conductor alarm indication in Control Room.

3. Standing instruction needed to be given to the all substation

personnel for not changing the relay settings without approval of

RT/MRT wing.

Fault had occurred in 220kV

Mahalingapura-Narendra line-2. Due to

the

failure of relay operation at

Mahalingapura,

breakers at remote end tripped which

resulted in bus dead condition.

25-10-2014GD-1 at

Mahalingapur

a Substation

of KPTCL

38/G

D/3.1

Pending

Mail recieved on 27-05-2015 (KPTCL):

1. KPTCL has taken action to provide bus bar protection to 220kV buses.

2. Over current relay Settings of ICTs to be reviewed by PGCIL.

Mail received on 29-07-2015 (KPTCL):

Initial Tendering stage

KPTCL Mail recieved on 23-01-2016:

Detailed estimate prepared for taking up the work. CEE, Transmission

Zone, Gulbarga will take up necessary procurement and further

execution.

1. Bus bar protection shall be provided by asset owner ( i.e

KPTCL).

2. Settings for main distance protection & Overcurrent

protection shall be examined and reviewed.

3. Time synchronization of the Substation shall be ensured.

4. Correct DR shall be submitted to the SRLDC for trip analysis.

Pending

400/220 kV

ICT-1 & 2 at

MUNIRABA

D

34/I/6 As reported directional over current relay

of ICT’s operated due to snapping of

line jumper in 220kV Lingapur line.

16-07-2014 PendingKPTCL

GD-1 at

Kadra and

Kodasalli

hydro power

station

38/G

D/3.5

Annexure-IX

Page 3 of 12

Annexure-VI

Circuit breaker of 400kV Guttur-Hiriyur

line-1 failed at Guttur end while availing

shutdown for replacement of CVT. The

failure of breaker caused bus fault at

Guttur.

05-11-2014

at 11:42 hrs

GD-1 at

Guttur

Substation of

KPTCL

38/G

D/3.2

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

1.Existing Back up relays will be replaced by numerical type distance

relays.Procurement is in tendering stage. Remaining observations were

attended.

KPTCL Mail recieved on 23-01-2016:

Existing back up relays will be replaced by Main-2 protection. LOI issued

M/s Alstom for taking up the works.Remaining observations were

attended.

KPTCL Mail Recieved dated 25-05-2016:

Under the Scope of R&U. The work will be taken up by M/s Alstom

shortly.

KPTCL1. PCSC forum recommended KPTCL to replace the old static

distance protection relays with numerical relays.

2. PCSC forum also requested KPTCL to provide a broken

conductor alarm indication in Control Room.

3. Standing instruction needed to be given to the all substation

personnel for not changing the relay settings without approval of

RT/MRT wing.

Fault had occurred in 220kV

Mahalingapura-Narendra line-2. Due to

the

failure of relay operation at

Mahalingapura,

breakers at remote end tripped which

resulted in bus dead condition.

25-10-2014GD-1 at

Mahalingapur

a Substation

of KPTCL

38/G

D/3.1

PendingKPTCLKPTCL was requested to expedite the early implementation of

pending recommendations of:

1. Protection Audit (Phase-I & Phase-II)

2. PSAG-4, PSAG-5, and PSAG-8

Pending

Mail received on 27-05-2015 & 29-07-2015:

Latest satus of implementatin of Phase-1 &2 recommendations, PSAG

4,5 and 8 is being obtained from field. The Status will be updated witin a

weeks time.

KPTCL mail received on 23-01-2016:

'The following works are attended at 400kV Guttur SS :

1. Replacement of Hiriyur-1 line, Bus Coupler, Tie Bus coupler breakers

by new Alstom make breakers (3 new CBs commissioned) recently.

2. New CVTs provided for 400kV Hiriyur line-1 and commissioned on

21.01.2016

KPTCL mail received on 25-05-2016:

The following works are attended at 400kV Guttur SS :

1. Replacement of Hiriyur-1 line, Bus Coupler, Tie Bus coupler breakers

by new Alstom make breakers (3 new CBs commissioned) recently.

2. New CVTs provided for 400kV Hiriyur line-1 and commissioned on

21.01.2016.

3) Remaining works planned under R&U will be taken up by M/s

Alstom shortly.

39/I/5 Pending

Mail received on 28-04-2015:

1. In view of operating 220kV Ambewadi SS in split bus mode, action is

being taken up by KPTCL . Problem in the 220kV bus coupler breaker is

attended and isolator overhauling work is under progress. Spilt bus

operation at Ambewadi will be made possible at the earliest.

2. ICT protection system at Ambewadi and trippings occured at Supa GS

during the instance is checked up and remedial measures already

furnished in this regard.

Mail recieved on 29-07-2015:

Action is being taken by KPTCL for operating Ambewadi in split bus

mode. Problem in bus coupler breaker is attended.Isolator overhaulling

work is completed.PTs are already provided to 220kV Bus-II. After

commissioning of Bus-II PTs, Ambewadi can be operated in split bus

mode. Pending works will be completed within a months time.

KPTCL mail recieved on 23-01-2016:

Bus-II PTs yet to be commissioned.Planned to complete before end of

April-2016.

Pending1. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore the possibility of having split

bus operation at Ambewadi and submit the details of the same to

PCSC forum.

2. KPTCL shall provide the details of the tripping of Supa hydro

station connected downstream from 110 kV bus.

KPTCLTriggering incident was B-phase to earth

fault in 220kV Ambewadi- Nagzari line-1.

B-pole of breaker did not open at

Ambewadi end. LBB protection not

available at Ambewadi end. All elements

tripped on Zone-2 from remote ends.

22-12-2014

at 21:22 hrs

GD-1 at

220kV

Ambewadi

Station of

KPTCL

40/I/1

Mail received on 27-05-2015 & 29-07-2015:

C&R panels of 500MVA ICT 1&2 will be replaced under scheduled

R&M works. O&M personnel are instructed to take sufficient care in

order to avoid unwarrented trippings.

KPTCL mail received on 23-01-2016:

New C&R panels(with numerical relays) erected for 500MVA ICT-1 &2

under R&M work, which will be commissioned shortly.

KPTCL mail received on 25-05-2016:

New C&R panels(with numerical relays) erected for 500MVA ICT-1 &2

under R&M work, which will be commissioned shortly.

KPTCL1. PCSC forum recommended KPTCL to replace the relay with a

different make.

2. KPTCL was also requested to train the O&M personnel

adequately before performing any maintenance works to avoid such

unwanted trippings.

Suspected mal-operation of 220kV side

Rphase

over current relay

01-12-2014Tripping of

400/220kV

ICT-2 at

Hoody

substation of

KPTCL

Annexure-IX

Page 4 of 12

Annexure-VI

Line tripped on Yphase to earth fault from

both the ends

20-12-2014

at 22:20 hrs

220kV Sedam-

Tandur line

40/IV

/1

Mail received on 28-04-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage. 2. Action is being taken to restore the carrier protection for

220kV Sedam-Tandoor line. AR will be enabled.

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled after restoration of PLCC.

KPTCL mail received on 23-01-2016:

1. Bus bar protection panels pocured and erected at Sedam. Wiring ,

testing ,commissioning is being taken up.Planned to complete by April

2016.

2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled after restoration of PLCC.

PendingKPTCL 1. KPTCL to provide Bus bar and LBB protections for 220 kV

bus at Sedam S/s.

2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur

inter-state line.

R-Phase to ground fault occurred on

220kV Sedam-Shahpur line. Fault not

cleared from Sedam end due to stuck-

breaker condition. While the Sedam-

Sahapur line tripped from Shahapur end in

Zone-1, the other 220 kv lines from Sedam

tripped at remote ends in Zone-2. This

caused complete outage of 220kV Sedam

substation.

27-01-2015

at 8.00 hrs

Complete

outage at

220kV Sedam

Substation of

KPTCL (GD-

1)

41/I/4

Mail recieved on 29-07-2015:

Carrier protection is being restored for 220kV Sedam-Tandoor line at

Sedam end. After restoring the carrier protection , AR will be enabled.

KPTCL mail recieved on 23-01-2016:

Carrier protection is being restored for 220kV Sedam-Tandoor line at

Sedam end. After restoring the carrier protection , AR will be enabled.

KPTCL mail recieved on 25-05-2016:

SEE,SCADA to update the latest status

KPTCLKPTCL was requested to explore the possibility of providing A/R

feature to this line and submit the remedial measures to the PCSC

forum.

Pending

Mail received on 28-04-2015:

1. In view of operating 220kV Ambewadi SS in split bus mode, action is

being taken up by KPTCL . Problem in the 220kV bus coupler breaker is

attended and isolator overhauling work is under progress. Spilt bus

operation at Ambewadi will be made possible at the earliest.

2. ICT protection system at Ambewadi and trippings occured at Supa GS

during the instance is checked up and remedial measures already

furnished in this regard.

Mail recieved on 29-07-2015:

Action is being taken by KPTCL for operating Ambewadi in split bus

mode. Problem in bus coupler breaker is attended.Isolator overhaulling

work is completed.PTs are already provided to 220kV Bus-II. After

commissioning of Bus-II PTs, Ambewadi can be operated in split bus

mode. Pending works will be completed within a months time.

KPTCL mail recieved on 23-01-2016:

Bus-II PTs yet to be commissioned.Planned to complete before end of

April-2016.

Pending1. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore the possibility of having split

bus operation at Ambewadi and submit the details of the same to

PCSC forum.

2. KPTCL shall provide the details of the tripping of Supa hydro

station connected downstream from 110 kV bus.

KPTCLTriggering incident was B-phase to earth

fault in 220kV Ambewadi- Nagzari line-1.

B-pole of breaker did not open at

Ambewadi end. LBB protection not

available at Ambewadi end. All elements

tripped on Zone-2 from remote ends.

22-12-2014

at 21:22 hrs

GD-1 at

220kV

Ambewadi

Station of

KPTCL

40/I/1

GD-1 at

220kV Kadra

power Station

of KPCL

16-02-2015

at 12:56 hrs

KPCL Mail received on 28-05-2015:

1. Main-2 relays already installed and commissioned.

2. DC fuses are intact. Till date no such incidence occurred.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Mail received on 07-07-2015 , 21-10-2015 and 23-11-2015:

1. Completed.

2. Completed.

3. Possibility of DC-1 & DC-2 arrangement and splitting of DC will be

reviewed.

Triggering incident was B-phase to earth

fault had occurred in 220kV Kadra-

Kodasalli line. Line tripped from Kodasalli

end only. 220kV Kaiga-Kadra tripped in

Zone-3 from Kaiga end. Tripping of

evacuating lines caused bus shut down at

Kadra hydro station.

Pending41/I/1 1. KPCL to make functional the Main2 (EPAC) relay with the

help of KPTCL at the earliest.

2. KPCL to investigate the reason for DC fuse fail during

transient fault in 220kV Kadra-Kodasalli line including the testing/

checking of DC supply cables, breaker control cables, and trip

coils.

3. KPCL to ensure supply for Main-1& Main-2 protections, Trip

Coils (TC1, TC2) from separate battery banks.

Annexure-IX

Page 5 of 12

Annexure-VI

Fault in 220kV Ambewadi-Nagjheri line-212-03-2015

at 7:51 hrs

Complete

outage of

220kV

Ambewadi

substation of

KPTCL

42/I/2

(GD)

Mail received on 27-05-2015:

Carrier protection is put in to service. AR will be enabled at the earliest.

Mail received on 29-07-2015:

Action is taken for enabling AR for Mudashinge and Talandage lines.

Work is scheduled during first week of August 2015.

KPTCL mail received on 23-01-2016:

1) Replaced existing VXL by ABB make C&R panel for both interstate

lines on 21.04.2015. The ABB Engineer visited 220KV Chikodi on

05.11.2015 for enabling AR system to existing ABB make REL511 relay

for both interstate line, but AR system not enable due to internal cards

faulty. Hence action is being taken to replace the ABB,REL511 distance

relays within a months time.

KPTCL1. KPTCL to provide A/R feature on the 220 kV Chikkodi –

Talandage, and 220 kV Chikkodi –Mudashinge inter-state lines.

2. KPTCL to carry out E/F relay coordination for Chikkodi -

Talandage and Chikkodi –

Mudashinge lines in coordination with Maharashtra.

Lines tripped during test charging 220kV

Chikodi-Belgaum line-2 from Chikodi

end.

20-02-2015

at

06:40 hrs

Tripping of

220kV

Chikodi-

Talandage

and

220kV

Chikodi-

Mudshingi

line

42/II/

2

Mail received on 28-04-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage. 2. Action is being taken to restore the carrier protection for

220kV Sedam-Tandoor line. AR will be enabled.

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled after restoration of PLCC.

KPTCL mail received on 23-01-2016:

1. Bus bar protection panels pocured and erected at Sedam. Wiring ,

testing ,commissioning is being taken up.Planned to complete by April

2016.

2. Action is being taken to restore the carrier protection for 220kV

Sedam-Tandoor line. AR will be enabled after restoration of PLCC.

PendingKPTCL 1. KPTCL to provide Bus bar and LBB protections for 220 kV

bus at Sedam S/s.

2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur

inter-state line.

R-Phase to ground fault occurred on

220kV Sedam-Shahpur line. Fault not

cleared from Sedam end due to stuck-

breaker condition. While the Sedam-

Sahapur line tripped from Shahapur end in

Zone-1, the other 220 kv lines from Sedam

tripped at remote ends in Zone-2. This

caused complete outage of 220kV Sedam

substation.

27-01-2015

at 8.00 hrs

Complete

outage at

220kV Sedam

Substation of

KPTCL (GD-

1)

41/I/4

Pending

1. KPTCL to provide Bus Bar protection and LBB protection at

Sedam S/s and furnish

the status of their implementation to PCSC forum.

2. KPTCL to implement A/R feature on 220 kV Sedam-Tandur

inter-state line.

Pending1. KPTCL shall provide A/R feature on Ambewadi – Ponda 220 kV

D/C inter-state line.

2. Till the completion of R&M works for bus bar and LBB

protection, KPTCL shall explore

the possibility of having split bus operation at Ambewadi and

submit the details of the

same to PCSC forum.

KPTCL

15-02-2015

at 14:24 hrs

Complete

outage of

220kV Sedam

substation of

KPTCL

42/I/1

(GD)

Mail received on 27-05-2015: 1. Bus Bar protection will be provded

under R&U.

2. A/R yet to be enabled.

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

KPTCLFault occurred in 220kV Sedam-Shahpur

line

Pending

Mail received on 29-07-2015:

1. Procurement of Bus bar and LBB protection is in the final tendering

stage.

2. Action is being taken to restore the carrier protection for 220kV Sedam-

Tandoor line. AR will be enabled after restoration of PLCC.

Annexure-IX

Page 6 of 12

Annexure-VI

47/III

/8

Tripping of

220kV

Ambewadi-

Ponda line-2

02-08-2015

at 13:20 hrs

Line tripped on a transient fault in B-

phase. There is no

provision for auto reclose.

KPTCL to activate non-directional Over Current protection with a

time delay of 600-800 msec for Fuse

failure condition at Lingasugur.

Pending

ICT tripped due to operation of Over

current and Earth fault relay

14-01-2015

at 1:09

hrs

Tripping of

400/220kV

ICT-1 at

BTPS

43/II/

14

Pending

Tripping of

Unit-1&2

along with

400/220kV

ICT-2 at

Raichur TPS

06-08-2015

at 4:51 hrs

KPTCL Yet to be informed Pending

Mail received on 21-10-2015:

1) Anti-pumping contactors of all the nine 220KV Lines are in circuit and

tested periodically during AOH works of lines along with other

protections.

2) Completed.

3) Possibility to use both the 220kV buses as main bus under normal

operation is under review.

Mail recieved on 23-11-2015:

1) Completed

3) Two bus operation for 220kV buses : In place of existing CT switching

relays, High speed manual heavy duty change over switch of sufficient

current capacity will be retrofitted to all feeders at 220kV station and

same will be operated manually during changeover of feeder by one bus

to the other and this arrangement may facilitate to put both buses in

service. Time required for this retrofit is around 90days . However, this

work will be taken up only after retrofitting of electromagnetic relays

with numerical relays for Main-2 protection of all 220kV lines, for which

work is in progress.

KPCL1. KPCL to check the operation of anti-pumping relay on 220 kV

side and keep it in healthy condition.

2. KPCL to provide manual reset to the 220 kV side master trip

relay.

3. KPCL to use both the 220 kV buses as main buses under normal

operation, and should go for single bus operation only during

emergencies.

07-06-2015

at 01:35 hrs

Trippings at

220kV

Raichur TPS

46/II/

21

KPCL vide their mail dated 07.07.2015 informed that revised relay

settings would be incorporated in co-ordination with KPTCL.

Mail received on 07-09-2015 , 21-10-2015 and 23-11-2015:

Revised relay settings are awaited from KPTCL.

Revised relay settings furnished by KPTCL will be incorporated in co-

ordination with KPTCL shortly.

PendingKPCL to check the possibility of providing line differential

protection between RTPS and Yermarus stations.

KPCL

Yet to be informedKPTCL

220kV RTPS-Lingasugur line-2 tripped at

TPS end on operation of distance

protection zone-1. 400/220kV ICT-2 got

tripped on operation of earth fault

protection. 220kV RTPS-Lingasugur line-

1&3 tripped on distance protection

zone-2 and zone-3 respectively. Due to

tripping of ICT-2, the running units got

overloaded and it was mentioned that

under frequency occurred as units are

on load control. The Units got tripped

on under frequency.

47/II/

13

Till A/R is put into service on Ambewadi-Ponda line-1, KPTCL to

reduce Zone-2 time setting to zero sec. at Ambewadi end.

Annexure-IX

Page 7 of 12

Annexure-VI

47/III

/10

Tripping of

220kV

Ambewadi-

Ponda line-1

08-08-2015

at 10:51

hrs and 09-

08-2015 at

11:15 hrs

Line tripped on a B-phase to earth fault.

Line tripped as there is no provision for

auto-reclose

47/III

/12

Tripping of

220kV

Ambewadi-

Ponda line-1

17-08-2015

at 13:20 hrs

Line tripped on a transient fault . There is

no provision for Auto reclose.

220kV Ambewadi-Nagjheri line-2 tripped

on B-phase to earth fault. This resulted in

loss of supply to 220kV Ambewadi bus.

220kV Ambewadi-Ponda line-1&2 were

hand tripped after deenergization of bus at

Ambewadi.

KPTCL to fast-track providing A/R on all 220 kV lines emanating

from Ambewadi SS to prevent Station shut-down on temporary

faults.

KPTCL KPTCL mail received on 23-01-2016:

Will be complied in a months time.

Pending30-09-2015

at 10:41 hrs

Outage of

220kV

Ambewadi

station in

Karnataka

48/I/3

(GD)

48/I/2

(GD)

Complete

outage of

220kV

Peenya

Substation in

Karnataka

27-09-2015

at 4:23:17

hrs

All connected 220kV lines and

transformers were taken on 220kV North

bus as South bus was under shut down for

conversion of strung bus to rigid bus and

isolator replacement under R&M works.

Failure of HV side Y phase CT of

150MVA Transformer-3 occurred at

Peenya Substation which resulted in

operation of Differential and HV REF

protection. The failure of CT also resulted

in a 220kV bus fault in North Bus.

KPTCL to revise distance relay settings at Nelamangala end for

220 kV Nelamangala – Hebbal - Peenya line – 1 for the effective

line length of 17 km. These new settings can be appropriately

reviewed as and when the tie-arrangement at Hebbal is done away

with.

KPTCL KPTCL mail received on 25-05-2016:

Presentl 220kV Nelamangala -Hoody(i.e. nelamangala-Peenya-Hebbal -

Hoody line is made LIILO at Yelahanka sub station and breaker at

Peenya is kept open, necessary modification in distance relay settings

adopted for new configuration.

Pending

PendingYet to be informedKPTCLTill A/R is put into service on Ambewadi-Ponda line-1, KPTCL to

reduce Zone-2 time setting to zero sec. at Ambewadi end. Annexure-IX

Page 8 of 12

Annexure-VI

48/I/4

(GD)

Complete

outage of 220

kV HSR

substation of

Karnataka

06-10-2015

at 16:32 hrs

All connected 220kV lines at 220kV HSR

substation i.e. Somanahalli, EPIP, Hoody

and Nagnathapura tripped during the

incident. Triggering incident was fault in

220kV HSR-EPIP line

KPTCL to review distance relay settings at Naganathpura SS in

view of LILO arrangement at HSR Lay-out.

KPTCL KPTCL mail received on 23-01-2016:

ABB make REL 670 type distance relays provided to Somanahalli and

hoody lines. Planned to commission within 10 days.

KPTCL Mail recieved dated 25-05-2016:

New REL 670 relays erected in the panel. Testing and commissionng will

be done within a month's time.

Pending

49/I/1

.3

(GD)

Complete

outage of

220kV

Ambewadi

Substation of

KPTCL

29.10.2015

at 14:34 hrs

220kV Nagjheri-Ambewadi line-1 tripped

at 13:33 hrs due to B phase to earth fault.

Ambewadi was radially fed from Nagjheri

power station through 220kV Nagjheri-

Ambewadi line-2. Tripping of this line

caused 220kV Bus shut down at

Ambewadi and remaining lines and

transformers were hand tripped

1. KPCL to provide A/R on all 220 kV lines emanating from

Nagjheri PH.

2. KPTCL to provide A/R on all 220 kV lines emanating from

Ambewadi SS.

KPTCL Yet to be informed Pending

49/II/

15

Trippings at

Raichur TPS

12-11-2015

at 00:30 hrs

Running Unit-4, 5 and Unit-8 and 400kV

RTPS-Yeramaras TPS feeder got tripped

due to de-energization of both 400kV Bus-

1&2 at Raichur TPS

1. KPCL to carry out hot-line washing of RTPS-connected lines

regularly to avoid trippings due to fog and dust.

2. KPCL may see the feasibility of providing breaker flashover

protection at RTPS, and implement the same if possible.

KPCL Status informed during Special Meeting held on 03.06.2016:

Hot line washing was done previously.tender process is on for silicon

coating of insulators.

Pending

Failure of Lightning Arrestor of Y-phase

Line Reactor of 400kV Guttur-Hiriyur line-

1 and line tripped on distance protection

Zone-1. Bus-bar protection of 400kV Bus-

2 at Guttur substation also got operated

during the event sensing this through fault.

400/220 kV ICT-1 & 2 at Guttur, 400kV

Kaiga-Guttur-2, 400kV

Guttur-Narendra-2, 400kV Guttur-Hiriyur-

2 and 400kV Guttur-Munirabad which are

on 400kV Bus-2 got tripped during the

incident. 400kV Guttur-Narendra-1 which

was on Bus-1 also tripped at the same

time.

51/II/

21

Multiple

tripping at

400kV Guttur

sub-station

17-01-2016

at 18:53 hrs

KPTCL 1. KPTCL to configure all DR’s and EL’s at 400 kV Guttur SS so

that they will also get triggered for BBP operation.

2. KPTCL to ensure time-synchronization of all DR’s and EL’s

with GPS at their 400 kV Guttur SS.

KPTCL Mail received dated 25-05-2016:

SEE,RTC,Bangalore to update the status

Pending

220kV lines from Nagjheri power house

started tripping from 11:00 hrs due to fault

in lines. The sequence of tripping is shown

in SOE list. At 12:33 hrs, 220kV Narendra-

Ambewadi lines-1&2 got tripped which

resulted in loss of evacuation path to

Nagjheri station resulting in tripping of

running Units and complete outage at

Nagjhheri power station. 220kV

Ambewadi station also got de-energized

due to tripping of source feeders i.e.

220kV Narendra-Ambewadi-1&2 and

220kV Nagjheri-Ambewadi-1&2.

1. To avoid tripping of transmission lines on transient faults,

KPCL/ KPTCL is recommended to carry out periodic patrolling of

lines, and ensure their proper maintenance by carrying out jungle/

bushing clearance and trimming of tree branches within the RoW

of transmission lines as per the SRPC transmission line patrolling

guidelines (available under the menu item "All Uploads

Operation Miscellaneous Transmission Line Patrolling

Protocol / Guidelines for Southern Region" on SRPC website).

2. KPCL/ KPTCL to review operation of SPS at NPH for

functionality (reduction of generation with tripping of evacuating

lines) and healthiness.

3. KPCL to put 220 kV Kodasalli - Nagjheri D/C lines into service

if more than 200 MW generation from Kali Complex (with Nagheri

Contribution not less than 50 MW) is ensured on sustained basis.

KPCL/ KPTCL Status informed during Special Meeting held on 03.06.2016:

SPS is in condition at NPH healthy and It is provded for non auxilliary

units ie 3 and 6 of NPH

PendingComplete

outage of

220kV

Nagjheri

power station

and 220kV

Ambewadi

substation of

KPTCL

22-02-2016

at 12:36 hrs

51/I/3

(GD)

Annexure-IX

Page 9 of 12

Annexure-VI

52/I/3

(GD)

Complete

outage of

220kV

Shimoga

substation

22-02-2016

at 15:03 hrs

220kV Bus Bar protection operated during

failure of R phase CT in DVG-2 line bay.

KPTCL to operate 220 kV Shimoga on multi-bus operation under

normal conditions, put it on single-bus operation only under

emergency conditions.

KPTCL Yet to be informed Pending

53/II/

1 (GI)

Tripping of

ICT-3 at

Raichur

Substation

15-03-2016

at 12:28 hrs

ICT-3 tripped due to operation of back-up

earth fault protection during fault in

220kV RTPS-Raichur line-1.

KPCL/ KPTCL to check the ICT’s back-up (high-set) protection

settings, and ensure that they operate with a time delay of 100

msec.

KPCL/KPTCL KPTCL Mail Recieved dated 25-05-2016:

SEE,SCADA to update the status of healthiness of carrier protection of

220kV RTPS-Raichur 1 &2 lines

Status informed during Special Meeting held on 03.06.2016:

Revised settings will be uploaded in co-ordination with KPTCL

Pending

220kV Peenya-Nelamangala-3 tripped on

B-E fault at both ends. At the same time,

220kV Peenya-Nelamangala-4 tripped on

R-Y fault only at Nelamangala end, and

was in service from Peenya end. Due to

tripping of these two lines, 220kV Peenya-

Nelamangala-2 tripped on overcurrent

protection.

KPTCL to furnish a report on the tripping of 220 kV Peenya-

Nelamangala line-4 Nelamangala detailing the remedial measures

taken including the settings adopted for Z1B (Zone extension) and

Power Swing Block.

KPTCL KPTCL Mail received dated 25-05-2016:

SEE,RTC,Bangalore to update the status

Pending16-03-2016

at 11:39 Hrs

Complete

outage of

220kV

Peenya

Substation of

KPTCL

53/I/1

(GD)

1. KPTCL to configure the Auto-Reclosure (A/R) scheme at

Hoody end for all lines emanating from Hoody end in such a way

that in the event of occurrence of faults during A/R dead-time, (i) it

should immediately give a 3-ph trip, and (ii) A/R should go into

lock-out state, i.e., it must not reclose after the elapse of dead-time

of A/R.

2. As regards over-reaching of Kolar and Nelamangala end relays

for the fault on 400 kV Hoody – Kolar line-2, KPTCL and PGCIL

(SR-II) are recommended to modify the Z1B settings of the relays

used (7SA522) suitably so that they operate with a Zone-2 time

delay.

3. KPTCL to check the ICT’s back-up (high-set) protection

settings, and ensure that they operate with a time delay of 100

msec.

4. KPTCL to take steps to replace the solid state relays at Hoody

end on Hoody-Nelamangala lines – 1 & 2 with numerical relays at

the earliest.

KPTCL KPTCL Mail recieved dated 25-05-2016:

1. Incorporated.

3. With the existing electromechanical relays, it's not possible to add time

delay of 100 mSec. However, ongoing R&M works of Hoody included

complete ICT1 and ICT2 panel replacement having Numerical relays.

4.The solid state relays of Nelamangala-1 and Nelamangala-2 lines will

be replaced by numerical relays for which relays have been

identified,Will be attended in a month's time.

400kV Hoody-Nelamangala line-1&2,

400kV Hoody-Kolar line-1&2, 400/220kV

ICT-2 at Hoody tripped during the

incident. ICT-1&3 were hand tripped after

the incident.

26-03-2016

at 12:42 hrs

Complete

outage of

400kV Hoody

substation of

KPTCL

53/I/1

(GD)

Pending

PendingYet to be informed53/I/3

(GD)

Complete

outage of

220kV

Ambewadi

station of

KPTCL and

220kV

Nagjheri of

KPCL

18-03-2016

at 14:40 hrs

Ambewadi Narendra line-2 tripped on

fault and 220kV ambewadi Narendra line-

1 tripped due to over-loading. Running

Units at Nagjheri also tripped during the

event due to tripping of evacuating lines

1. KPCL to furnish a report on the reasons for Unit-6 tripping at

Nagjheri PH.KPCL/ KPTCL to modify suitably the SPS at Nagjheri

Power House such that it would also factor in the over loading of

Ambewadi-Narendra lines.

2. KPCL/ KPTCL to put 220 kV Kodasalli - Nagjheri D/C lines

into service if more than 200 MW generation from Kali Complex

(with Nagheri Contribution not less than 50 MW) is ensured on

sustained basis.

KPCL/ KPTCL

Miscellaneous

Annexure-IX

Page 10 of 12

Annexure-VI

36/II/

8

400kV

Raichur-

Munirabad

line

07-09-2014 B-phase to earth fault had occurred in line.

Line auto reclosed at Munirabad end and

failed to reclose at Raichur end.

KPTCL:

PD (pole discrepancy) time delay would be changed.

PGCIL /

KPTCL

Yet to be informed Pending

with

KPTCL

43/II/

12

Multiple

tripping at

400kV

Raichur(PG)

and Raichur

thermal

11-04-

2015at

18:04 hrs

400kV Raichur(PG)-Gooty line-2,

400kV Raichur TPS-Raichur(PG)

line-1&2, 400kV Raichur-

Mahboobnagar, Unit#5 at RTPS

tripped during the incident

KPCL, KPTCL and PGCIL (SR-I) to furnish the action taken report

on the

recommendations given by PSAG members held at Raichur on 22-

04-2015 and

23-04-2015.

KPCL/KPTCL/

PGCIL(SR-I)

Yet to be informed Pending

Tripping of

Unit 1 at

NCTPS

24-05-2015

at 19:13 hrs

ID Fan trip

Tripping of

Unit 1 at

MEPL

24-05-2015

at 19:13 hrs

Coal Mill tripped

Tripping of

Unit 1 at

Krishnapatna

m

24-05-2015

at 19:17 hrs

Generator Protection operated

Mail received on 26-05-2015 from TSTRANSCO:

It is found that the main-2 ABB make REL316 type distance relay was

defective and same was replaced with MICOM P444 by M/s.PGCIL on

23.04-2015. After replacement of main-II, DR can be extracted from this

relay. For EL in to service, some field winding is pending which is being

taken up in this month.

PGCIL mail recieved on 27-04-2016:

End to end PLCC tunning carried out

1. KPCL to review REF setting (DMT or IDMTL) for unit-7 by first

week of April, 2015 and

inform the same to PCSC forum.

2. TSTRANSCO to furnish Mehaboobnagar’s DR and EL and the

reasons for distance relay

operation at their end within a week’s time.

3. PGCIL (SR-I) to rectify the issues relating to A/R operation,

relay reach (Z2), reverse reach

(Z4) and SOTF auxiliary contacts within a week’s time, and submit

the actions taken to

PCSC forum.

KPCL/TSTRANS

CO/PGCIL (SR-I)

Pending

with SEL

400kV Raichur TPS-Raichur(PG) line-

1&2, 400kV Raichur-Mahboobnagar,

Unit#7 and ICT-2 at RTPS tripped

during the incident. B phase to earth

fault had occurred in 400kV Raichur

TPS-Raichur line-1

09-03-2015

at

06:36 hrs

Multiple

tripping at

Raichur

thermal

power station

of

KPCL

42/II/

18

Mail recieved on 28-04-2015: End to end testing of PLCC has

been done and problem in the PLCC is atttended.

Mail received on 27-05-2015 (KPTCL) & 29-07-2015:

End to end testing of PLCC has been done and problem in the PLCC is

atttended. Phase discrepancy in the relay operation is to be checked

jointly.

Mail recieved on 02-09-2015:

Problem is in identification of phases at Talguppa end. To be rectified by

M/s KPTCL.

Pending1. PGCIL and KPTCL to ascertain the reason for the phase

discrepancy in the relay operation and take suitable remedial

measures.

2. KPTCL to check the PLCC operation at Talaguppa end and

submit the report to the PCSC forum.

PGCIL/ KPTCLOn account of R-phase to earth fault, line

tripped at Hassan end due to operation of

distance Zone-2 and non-receipt of carrier.

From D.R of Talaguppa end it is observed

that fault had occurred in Yphase.

01-01-2015

at

13:38 hrs

Tripping of

400

kV

TALAGUPP

A

– HASSAN

line

40/II/

3

44/I/3

(GD)

1. All Tripped units, viz., Krishnapatinam, MEPL, Raichur, NCTPS

to submit a detailed report

on this event including the remedial measures taken to PCSC

forum.

2. KPCL to check the excitation system of Unit 8 of RTPS, and

submit the remedial measures

taken to PCSC forum.

KPCL/ MEPL/

APGENCO/

TNEB

TANGEDCO vide their mail dated 07.07.2015 informed that as per the

discussion and recommendation of 44th meeting of PCSC held on

28.05.2015, a time delay of 2 Sec had been introduced for the above

tripping for all the ID fans at NCTPS-II.

MEPL vide their mail dated 14.09.2015 informed that they have

implemented 2 seconds delay for under voltage tripping of all Drag Chain

Feeder Conveyors. And this has been done for both the Units.

Pending

with

KPCL,

APGENC

O

Annexure-IX

Page 11 of 12

Annexure-VI

Tripping of

Unit-8 at

RTPS

24-05-2015

at 19:19 hrs

Tripped on Overvoltage.

KPTCL Mail Recieved dated 25-05-2016:

Availability of week end infeed with eco feature to be confirmed by

SEE,RTC,Hubli

PendingKPTCL/ KPCL/

NPCIL

44/I/3

(GD)

1. All Tripped units, viz., Krishnapatinam, MEPL, Raichur, NCTPS

to submit a detailed report

on this event including the remedial measures taken to PCSC

forum.

2. KPCL to check the excitation system of Unit 8 of RTPS, and

submit the remedial measures

taken to PCSC forum.

KPCL/ MEPL/

APGENCO/

TNEB

TANGEDCO vide their mail dated 07.07.2015 informed that as per the

discussion and recommendation of 44th meeting of PCSC held on

28.05.2015, a time delay of 2 Sec had been introduced for the above

tripping for all the ID fans at NCTPS-II.

MEPL vide their mail dated 14.09.2015 informed that they have

implemented 2 seconds delay for under voltage tripping of all Drag Chain

Feeder Conveyors. And this has been done for both the Units.

Pending

with

KPCL,

APGENC

O

1. KPTCL/ KPCL to see the possibility of implementing Weak

Infeed logic with Echo feature enabled by Under

Voltage (27) element on Kadra-Karwar lines 1 &2, and implement

the same if feasible.

2. NPCIL to time-coordinate Kaiga’s DEFR settings with (i) Zone-2

settings at Kaiga, and (ii) primary protections of the lines

emanating from Kadra and Kodasalli.

3. KPCL to ensure time-sync of EL’s, and healthiness of the Fault

Locators at Kadra.

220kV Kadra-Karwar lines-1&2 tripped

on earth fault in B-phase in zone-2.

Kaiga-Kadra line tripped at Kaiga end

only on operation of directional eath

fault protection.

31-07-2015

at

11:44 hrs

Tripping of

220kV Kadra-

Karwar line-

1&2 and

220kV

Kaiga-Kadra

line

47/II/

7

Annexure-IX

Page 12 of 12

Annexure-VI

S. No Name of

SubstationDetails of work Status of Implementation of Protection Audit Recommendations Remarks

Dead Earth fault in 220 V DC set 1 & 2. Completed Complied

relays not Synchronised with GPS.

The work will be completed by March 2015.

Latest Update as on 25-08-2015:

GPS received at site. The work will be completed by December 2015.

Latest Update vide mail on 27-01-2016:

Completed.

Complied

A/R Scheme for 220 kV Lines not available for

lines.Completed Complied

2 220 kV Kadra

(Gen) Carrier protection is out of service for Karwar 1

& 2 feedersCompleted Complied

3 220 kV Kodasalli

S/S (Gen) Carrier protection is not in service for all feeders

(the real time testing is pending).Completed Complied

4

220 kV Nagjhari

Power House

The LBB relay time & current are sdet at 1.5 sec

& 0.2 A for all feeders and generating

transformers.

Completed Complied

220 V DC earth fault persisting negative dead

grounded

Latest Update as on 25-08-2015:

Negative dead ground is removed. Partial ground is present. The work will be completed by December 2015.

Latest Update vide mail on 27-01-2016:

Completed

Complied

LBB Relay RAICA RXKL1 setting for ICT-II is

kept at 50 mA.Completed Complied

LBB relay timing is observed to be 0.7 sec

which is high, can be reduced to 250 to 300

m.sec in coordination with pole discrepancy

relay of breaker.

Completed Complied

KPCL

Phase-I

1 220 kV BTPS

5 220 kV Raichur

TPS

6 220 kV Sharavathi

SS (Gen)

STATUS OF IMPLEMENTATION OF PROTECTION AUDIT RECOMMENDATIONS

Annexure-X

Page 1 of 14

Annexure-VI

Carrier protection should be kept in service for

the feeders having no carrier protection.

The work will be completed by July - 2015.

Latest Update as on 25-08-2015:

Completed

Complied

DC earth leakage should be arrested on top

priority to avoid spurious trippings due to DC

earth leakage.

Completed Complied

Substation GPS to be connected to event logger

and protection relays for correct recording of the

sequence of events.

e-NIT floated on 15.09.2014. The work will be completed by December-2015.

Latest Update as on 25-08-2015:

NIT was issued through e-portal. LOA for Supply & Erection of Disturbance Recorder & GPS issued to M/s Alstom

T&D India Ltd., Chennai on 26.06.2015. Contract agreement executed.

Latest Update vide mail on 27-01-2016:

Letter of Award issued to M/s Alstom T&D India Ltd., Chennai for Supply & Erection of Disturbance Recorder &

GPS on 26.06.2015. The firm has completed site visit for collection of data’s from site and is now preparing

schematic drawings.It is estimated that the work completion period may extend until 30.12.2016.

Pending

Complied

Feeders with same Make & Type relay as Main-I

& Main-II should be changed with different

Make/Type relays for Main-I & Main-II.

LOA issued to M/s Alstom T&D India Ltd. Bengaluru. The work will be completed by December - 2015.

Latest Update as on 25-08-2015:

LOA dtd. 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Review of drawings completed. Materials

received at site. The work will be completed by December - 2015.

Latest Update vide mail on 27-01-2016:

LOA dated: 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Erection work completed for all 8 Lines &

2 BCs except for S-2 line, which is in pregress.The erection works involve obtaining prior line clearance from the

State Load Dispatch Centre hence the erection work for remaining line is expected to complete by 31.01.2016.

Status informed during Special Meeting held on 03.06.2016:

Completed

Complied

6 220 kV Sharavathi

SS (Gen)

Feeders having O/C and E/F relays as Main-II to

be replaced with distance relays for good

protection coordination on 220 kV Grid.

LOA issued to M/s Alstom T&D India Ltd. Bengaluru. The work will be completed by December - 2015.

Latest Update as on 25-08-2015:

LOA dtd. 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Review of drawings completed. Materials

received at site. The work will be completed by December - 2015.

Latest Update vide mail on 27-01-2016:

LOA dated: 15.12.2014 issued to M/s Alstom T&D India Ltd. Bengaluru. Erection work completed for all 8 Lines &

2 BCs except for S-2 line, which is in pregress.The erection works involve obtaining prior line clearance from the

State Load Dispatch Centre hence the erection work for remaining line is expected to complete by 31.01.2016.

Status informed during Special Meeting held on 03.06.2016:

Completed

Annexure-X

Page 2 of 14

Annexure-VI

A/R Selection switch is kept in non auto mode

for all 400 kV lines.

Dead 220 V DC Earth fault for both sets i.e.

Positive to Earth 235 V.Completed Complied

GPS time synchronisation for all the relays &

DR not carried.

The work will be completed by May 2015.

Latest Update as on 25-08-2015:

GPS received at site. The work will be completed by December 2015.

Latest Update vide mail on 27-01-2016:

Completed.

Complied

High setting for the bus bar differential

protection i.e. 325 V.

The work will be completed by March - 2015.

Latest Update as on 25-08-2015:

Assistance of OEM required. OEM opined that the setting is in line with latest fault levels, considering fault level as

50kA.

Latest Update vide mail on 27-01-2016:

Assistance of OEM required. OEM opined that the setting is in line with latest fault levels, considering fault level as

50kA. This shall be reviewed as per the opinion of OEM and hence may please be removed from the list.

Status informed during Special Meeting held on 03.06.2016:

Completed

Complied

7

A/R function for 400kV lines shall be completed by May 2015.

Latest Update as on 25-08-2015:

Timers dispatched from supplier. Software programming is completed during previous shut down availed on lines.

One more shut down is required for uploading settings and to modify wiring. A/R function for 400kV lines shall be

completed by December 2015.

Latest Update vide mail on 27-01-2016:

Request sent to State Load Despatch Centre for availing LC for enabling A/R function for 400kV lines.The erection

works involve obtaining prior line clearance from the Sate Load Dispatch Centre hence the work completion period

may extend till 30.03.2016.

Status informed during Special Meeting held on 03.06.2016:

Completed.

Complied

400 kV BTPS

Annexure-X

Page 3 of 14

Annexure-VI

Pole descripency relay setting kept at 0.1 Sec for

all the lines.

The work will be completed by July - 2015.

Latest Update as on 25-08-2015:

Timers dispatched from supplier. The work will be completed by December - 2015.

Latest Update vide mail on 27-01-2016:

Completed.

Complied

220 V DC earth fault persisting with leakage

current of 15 mACompleted Complied

PD settings for Munirabad, BTPS and

Mahboobnagar kept at 0.1 secCompleted Complied

RTPS-Munirabad line Zone-II setting (26.880

Ohm) is more than Zone-III (26.44 Ohm)Completed Complied

No fault locator working for Munirabad and

Mehboobnagar lines