Villianur Is an Important System Element in Grid Operation

SOUTHERN REGIONAL POWER COMMITTEE BENGALURU Minutes of the Special Meeting on the Pending Protection Issues of Puducherry Substations held on 20th July, 2018

A. Introduction

A Special Meeting was held on 20th July, 2018 at PED HQ, Puducherry to deliberate on all outstanding protection issues involving their substations. The list of participants is enclosed at Annexure-I.

Sh. S.R. Bhat, Member Secretary (MS), SRPC welcomed Officials of PED, NLCIL, PGCIL (SR-II) to the meeting and thanked Sh. D. Ravi, SE-I & HoD of PED for arranging the meeting at short notice. Then, outlining the reasons for calling special meeting, he stated that 230 kV substation of PED at Villianur is an important system element in grid operation. However, of late it was seen that there were three grid disturbances (30th May, 5th June and 15th June 2018) in Villianur S/S affecting all the loads connected to it. The adverse effect on the load due to the disturbance was to the extent of 100 -120 MW which is fairly sizeable and is about 35 % of the total demand of PED system.

He informed that in the aftermath of the grid disturbances of 2012, Central Electricity Authority was keeping a regular watch on the grid disturbances in the country. Periodic reports were also being submitted to the Ministry of Power. Hence, three grid disturbances in fairly quick succession in PED system had attracted attention.

Of the three events, the first two were discussed in the 75th meeting of PCSC held on 28.06.2018. However, owing to absence of PED representatives, these events, which primarily occurred because of failure of some substation equipment along with non-operation of required protections, could not be analysed in detail.

He also stated that recognizing the importance of 230/110 kV Villianur and Bahour substations in supplying power to Puducherry, comprehensive protection audit of the same was conducted by SRPC teams in July, 2017, and a no. of measures were suggested for system improvement. However, based on the status furnished by PED, it was noted that not much progress was observed with regard to implementation of remedial measures.

In view of the gravity of the matter, it was therefore decided to convene this meeting to analyze these Grid Disturbances in detail, to review the status of implementation protection audit remarks of Villanur & Bahour substations, and to identify various short-term and long-term measures for time-bound implementation in the interest of smooth grid operation.

Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 1

B. Analysis of the Villianur GD’s on 30.05.2018, 05.06.2018 & 15.06.2018

The Grid Disturbances that occurred on 30.05.2018, 05.06.2018 & 15.06.2018 at 230/ 110 kV Villianur Substation were thoroughly analysed in the meeting. Their analysis, along with necessary measures required to be taken by various partied involved, is enclosed at Annexure-II for kind reference. The details of the tripping events including relevant PMU plots presented by SRLDC in the meeting are also enclosed at Annexure-V for kind reference.

PED, PGCIL (SR-II) and NLCIL were requested to initiate necessary action to comply with the measures recommended.

C. Review of status of implementation of Protection Audit Recommendations of Villanur and Bahour Substations.

Subsequent to a similar GD event at 230/ 110 kV Villianur SS on 19.05.2017 (triggering incident in this case was failure of CT in 110 kV Villianur-Kurumbapet), comprehensive protection audit of 230/ 110 kV Villinaur SS and 230/ 110 kV Bahour SS was conducted by SRPC teams in July, 2017, and a no. of recommendations were given for system improvement.

Based on the status furnished by PED vide their mail dated 10.07.2018, implementation status of above remarks was reviewed in the meeting, and the same is enclosed at Annexure-III for kind reference. It was noted that even though implementation of majority of the remarks is linked with PSDF funding, there is a significant chunk of remarks which have no financial implications, but solely related to revising existing relay settings, and could have been attended by this time.

PED was therefore asked to attend the latter set of remarks on priority basis in a month’s time. Further, since various works had already been commenced through PSDF funding, PED was asked to complete the remaining remarks also in a phased and time-bound manner.

D. Review of compliance status of the recommendations given in the special meeting held on 3rd January, 2017 w.r.t. Neyveli Grid Disturbance on 25.11.2016

In the meeting, the compliance status of the recommendations given in the Special Meeting held on 3rd January, 2017 w.r.t. Neyveli Grid Disturbance on 25.11.2016 was reviewed, and the same is enclosed at Annexure-IV for kind reference & necessary action by PED, NLCIL & TANTRANSCO.

It was noted that TANTRANSCO representatives had not come to attend the meeting.

Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 2

E. Measures identified for time-bound implementation of various protection remarks by PED

While appreciating the steps and constraints expressed by PED, the following measures were highlighted for time bound and focused implementation:

 Since the protection systems in place at Villianur & Bahour substations are not in compliance of various protection standards & regulations, early & time-bound implementation of the ongoing schemes for renovation and up-gradation of substations through the Power System Development Fund was emphasized.  In the Review Meeting of PSDF held in January 2018, Chairperson, CEA had expressed concern over the slow pace of implementation. PED had also been requested to kindly step up the pace of implementation.  It was noted that PED is in the process of submitting a revised DPR for additional PSDF funding to undertake further works for improving protection systems at Villianur & Bahour substations. However, since considerable time had lapsed since the Review Meeting in January 2018, PED was asked to expedite the same.  It was noted that at present PED is dependent on external agencies for carrying out testing of various electrical equipment & relays & protection oriented trouble shooting. Similarly, over-dependence on TANTRANSCO engineers was hampering the works. PED was therefore requested to initiate steps to suitably develop manpower of PED in various activities such as relay setting calculations etc. or alternatively, approach central PSU such as POWERGRID, who would undertake the works on consultancy basis. The necessity of establishing Standard Testing Lab and procurement of essential testing equipments to cater to all 230 kV substations under PED control was high-lighted.  PED was asked to ensure regular participation of their Officers in the Sub-Committee Meetings of SRPC, especially those relating to Protection.  In view of the criticality of Villianur & Bahour substations, PED was also asked to identify a Nodal Officer at senior level to make periodic assessment of status of implementation of their protection audit remarks, and take steps to remove any bottlenecks by bringing them to the notice of their higher management for efficient redressal.

F. Vote of Thanks

MS, SRPC thanked SE-I & HoD, PED and other Officials from Puducherry ED, NLCIL, PGCIL (SR-II) & SRLDC for participating in the Meeting. He hoped that with active co-operation & due diligence by PED, measures as chalked out would be given priority for improving protection systems at Puducherry Substations, and effective monitoring mechanisms would be put in place to improve their operational performance.

*****

Minutes of the Special Meeting on Pending Protection Issues of Puducherry Stations held on 20th July, 2018 Page 3

Annexure-I Annexure-II

Analysis of the Villianur GD’s on 30.05.2018, 05.06.2018 & 15.06.2018

Sl. Details of Event Date &Time Reason Remarks Category No.

Triggering incident was failure of 230 kV side R-ph CT of 230/ 110 kV of ICT -2 at 230/ 110 kV Villianur station. 230 Complete outage of 08:40 hrs on kV Neyveli - Villanur and 230 kV Pondy - Load Loss: 1 230/ 110 kV Villianur GD-1 30-05-2018 Villianur lines tripped from Neyvelli end 130 MW Substation and Pondycherry end respectively. This led to loss of supply to 230 kV Villianur Station.  Stipulated TR formats were not used by PED and NLCIL SLD:  The single line diagram of 230/ 110 kV Villianur SS as furnished by PED is attached at the end.

Tripping of 230 kV Villianur – NLC-II line: NLC-II (NLCIL) end:  As per FIR/DR/EL/TR, line tripped at 08:50:00.544 hrs due to operation of SOTF O/C protection.  Time-sync of Protection Relays with GPS needed to be ensured at NLC-II. Villanur (PED) end:  As per FIR, the line was kept holding from Villianur end.  It was stated in TR that 230 kV R-ph HV-II CT of 100 MVA Auto Transformer-II failed resulting in tripping of both 230 kV Villanur – NLC2 line and 230 kV Villianur-Pondy line from remote ends. The respective breakers at Villianur 230 KV SS end were holding and only the breakers at Neyveli and Pondy ends got tripped.

Tripping of 230 kV Villanur – Pondicherry line: Pondycherry (PGCIL-SR2) end:  As per FIR/DR/EL/TR, line tripped at 08:42:23.564 hrs due to DPR, Z2 (with Tz2 = 250 msec) operation. Villanur (PED) end:  As per FIR, the line was kept holding from Villianur end.  It was stated in TR that 230 kV R-ph HV-II CT of 100 MVA Auto Transformer-II failed resulting in the tripping of both 230 kV Neyveli - Villanur line and 230 kV Pondy - Villianur line. The respective breakers at Villianur 230 KV SS end was holding and only the breakers at Neyveli and Pondy ends tripped.  Remedial action informed by PED:  Failed CT (Year of manufacture:1985, Year of commissioning: 1987) was replaced with R-phase CT released from 230 kV Pondy-Villianur Line as no spare CT with similar CT ratio 150-300-600- 1200/1-1-1-1A was available on hand at Villianur SS. Auto Transformer-II was brought back into service at 01:15hrs on 31.05.2018.  Remaining Y and B-phase CTs of 230KV Pondy Line were released and one set of new CTs with CT ratio 400-800-1000-1200-1600/1-1-1-1A were erected in Pondy line bay on 31.05.2018. After having conducted pre-commissioning tests by P&C wing of TANTRANSCO Limited, Villupuram, 230 kV Pondy-Villianur line was closed at 20:20 hrs on 11.06.2018 and brought the Villianur SS into Grid. However, 230 kV Busbar protection scheme was kept out of service before energizing the Pondy line since CT ratio adopted for Busbar protection to 230 kV Neyveli, HV-I and HV-II (600/1A)

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 1/8

Annexure-II differed from that of 230KV Pondy Line (1200/1A).  Six numbers of new 230 kV CTs with CT ratio 300-600-1000-1200-1600/1-1-1-1A have been supplied to this department by M/s PGCIL on 04.07.2018 in lieu of CTs borrowed by them. Actions have been initiated to replace the in-service aged 230KV HV-I & HV-II CTs with the newly supplied CTs. After the replacement of CTs, the 230 kV Busbar protection scheme will be brought back into service. P&C wing of TAN TRANSCO Limited, Villupuram has been requested to carry out pre- erection test on the new CTs in order to commence the CT erection work.

 Remedial action informed by NLCIL:  When enquired about the reasons for SOTF operation at NLCIL end on 230 kV NLC2 – Villianur line, NLCIL informed that it was due to old setting of SOTF protection (2000 A) implemented from an external relay. As a remedial measure, its setting was now revised to 2800 A.

Deliberations:  It was noted that the triggering fault (CT blast) was within zones of differential protection of 230/ 110 kV Autotransformer - II and 230 kV busbar protection. However, non-operation of these primary protections during the incident was suspected/ attributed to the fact that since 110 kV side was radially fed, shorting/ bypassing of the CT from 230 kV side during the incident on account of engulfing arc might have resulted in zero difference current, and their consequent non-operation.

 When enquired about the time-line for restoring 230 kV BBP, PED informed that they would be availing shutdowns on 28.07.2018 and 04.08.2018 to complete replacement works of CT’s, hence by the end of first week of August, 2018, they would be able to put 230 kV BBP back into service at Villianur SS.

However, considering the frailty of the substation equipment, and the need to avoid delayed clearance of faults during this intermediate time, PGCIL (SR-II) and NLCIL were asked to immediately effect the following changes:  PGCIL (SR-II) to revise Zone-2 time-setting to 150 msec at Pondy end on 230 kV Pondy - Villianur line.  NLCIL to revise Zone-2 time-setting to 150 msec at NLC TS-2 end on 230 kV NLC TS2 - Villianur line. The above revised settings would be retained till 230 kV Busbar protection is put into service at 230/ 110 kV Villianur SS, which information would be shared by PED with all concerned.

 When enquired about why interlock with CB status was not employed for SOTF protection, NLCIL informed that such provision was not available in the external relay. However, after commissioning of Main-II relay in about 6 months time, SOTF protection with CB status interlock would be provided from the same.  In this regard, it was noted that since the same functionality is being provided by the existing O/C & E/F back-up protections of the line from NLC-TS2 end, NLCIL was asked to check if the operating characteristics of SOTF protection implemented from the external relay at NLCIL end on 230 kV NLC TS2 - Villianur line could be changed to IDMT. If so, the same shall be put to use. Else, NLCIL was asked to disable the SOTF protection implemented from the external relay. In the event of disabling SOTF protection, NLCIL was also asked to take steps for providing Main-II relay for the line at the earliest, and implement SOTF protection from it.

 In this regard, PED was asked to take steps to comply with the protection audit remarks of 230/ 110 kV Villianur SS in a phased and time-bound manner.

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 2/8

Annexure-II Triggering incident was the failure of R-ph breaker of 110 kV Kalappet-Villianur line got failed at Villianur end. Fault was Complete outage of cleared by tripping of the upstream 11:23 hrs on Load Loss: 2 230/ 110 kV Villianur feeders. 230kV NLC St-2 Villianur tripped GD-1 05-06-2018 120 MW SS of PED at NLC end and 230kV Pondy Villianur line tripped at Pondy end on Zone-3 distance operation, resulting in the loss of supply to 230 kV Villianur station.  Stipulated TR formats were not used by PED and NLCIL

SLD:  The single line diagram of 230/ 110 kV Villianur SS as furnished by PED is attached at the end.

Tripping of 230 kV Villanur – NLC-II line: Villianur (PED) end:  As per FIR, line was kept holding. NLC-II (NLCIL) end:  As per FIR/DR/EL/TR, line tripped at 11:23:54.963 hrs due to DEF (Tef =2.15 sec) operation.

Tripping of 230 kV Villanur – Pondicherry line: Villianur (PED) end:  As per FIR, line was kept holding. Pondicherry (PGCIL-SR2) end:  As per FIR/DR/EL/TR, line tripped at 11:23:50.052 hrs due to DPR, Z3 operation (observed Tz3 = 0.5 sec).  In the furnished DR & EL, along with Z3_Trip, Z4_Trip was also observed at the same time.

As per PED report furnished vide their mail dated 21.06.2018 :  For 110 kV Villianur – Kalapet feeder fault, Main-I distance protection relay of the said feeder picked up the fault, and actuated the trip relay. Due to impact of the fault, B-ph pole column of the breaker failed and hence the feeder breaker failed to open.  HV & LV O/C relays of both Auto-Transformer-I & Auto-Transformer-II acted for R, Y & B phase, but none of the breakers of Auto-Transformers got opened as the terminal fuse of 110 V Station Battery Bank was found to be blown out.

 Remedial action informed by PED:  Terminal fuse of 110 kV Station Battery Bank was replaced. Cause for the blown out of fuse was being studied.  A work order has been issued to a contractor M/s Ragavi Engineers, Puducherry vide Order No.05/ED/EE-Auto SS/AEE-M-VASS/2018-19, dated 06.07.2018 at the cost of Rs. 97, 350/- for providing 4 sets of pipe in pipe chemical earthing at the back yard of control room to strengthen the existing earthing of Control & Relay panels, AC & DC Distribution panels and 110 Volt Station and 48 Volt PLCC battery chargers within 15days from the date of work order.  Failed Kalapet feeder breaker (Year of manufacture: 1987, Year of commissioning: 1987) was replaced with new circuit breaker. Also the aged CTS of Kalapet feeder (Year of manufacture: 1986, Year of commissioning: 1987) were also replaced with new CTs as a precautionary measure.  Switch yard earthing was measured during the total shutdown availed in Villianur SS on 30.06.2018. Individual and combined earth pit value of Kalapet feeder bay was observed to be

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 3/8

Annexure-II 3 ohm. However, other earth pit values are observed on higher sides, actions have been initiated to strengthen earthing of switch yard.

Deliberations:  It was noted that even though the triggering cause of the GD had to do with the failure of operating mechanism of the 110 kV CB on 110 kV Villianur – Kalapet line at Villianur end, the main cause for the GD was the failure of 110 kV Protection DC which led to non-opening of the HV and LV breakers of Autotransformers on O/C & E/F protections.

Here it was also noted that the claim of PED that O/C & E/F protections had operated but the corresponding HV & LV breakers of Autotransformers – I & II could not be sustained given the fact that same DC was energizing both relays and breakers.

Thus, it was suspected that failure of 110 kV protection DC could be due to issues relating to improper earthing of various equipment in the substation, which was also corroborated by the measured high earth-resistance values of various pits.. As informed by PED, since steps had already been initiated in the direction of improving earth-pit resistances, they were also asked to carry out station earth-mat integrity test covering both 230 kV & 110 kV voltage levels.

 In this regard, it was also noted that since 110 kV sides of Villianur and Bahour Sations are radially fed, PGCIL (SR-II) and NLCIL were asked to revise Zone-3 timing on 230 kV lines emanating from 230 kV Pondy and 230 kV NLC TS-2 to 0.8 sec as mentioned below:

 PGCIL (SR-II) to revise Zone-3 time-setting to 800 msec at Pondy end on 230 kV Pondy - Villianur line & 230 kV Pondy – Bahour line.  NLCIL to revise Zone-3 time-setting to 800 msec at NLC TS-2 end on 230 kV NLC TS2 - Villianur line & 230 kV NLC TS@ - Bahour line.

 PGCIL (SR-II) was also asked to examine the reasons for Zone-4 trip, and correct the same.

 In this regard, PED was also asked to take steps to comply with the protection audit remarks of Villianur SS in a phased and time-bound manner.

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 4/8

Annexure-II Triggering event was failure of B-phase 230 kV Current Transformer (Make: TELK) of HV-I Breaker of 230/110 kV 100 MVA Auto Transformer-I at Villianur substation. Fault was cleared by tripping Complete outage of of source feeders i.e. 230 kV Neyveli- 230/ 110 kV Villianur 07:29 hrs on Load Loss: GD-1 3 Villianur Line breaker at NLC TS-II and SS of PED 15-06-2018 102 MW 230KV Pondy-Villianur Line Breaker at 400KV Pondy S/S. Fault was cleared in 350 ms as observed from PMU data plot. This in-turn resulted in loss of supply to 230 kV Villinanur station.

 Stipulated TR formats were not used by PED and NLCIL

Tripping of 230 kV Villanur – NLC-II line: Villianur (PED) end:  As per FIR/TR, line was kept holding.  It was stated in FIR/TR that Failure of B-phase 230KV Current Transformer (Make: TELK, Sl. No.:230116-39, Year of Manufacture: 1985) of HV-I Breaker of 230/110 kV 100MVA Auto Transformer- I at 07:29 hrs on 15.06.2018 due to ageing, resulted in tripping of 230 kV Neyveli-Villianur Line breaker at TS-II, Neyveli and 230 kV Pondy-Villianur Line Breaker at 400 kV Pondy SS. Due to this, supply to 110/ 22 kV substations, viz., Marapalam SS, Venkata Nagar SS, Kalapet SS, and Villianur SS fed from this station got affected. NLC-II (NLCIL) end:  As per FIR, line tripped at 07:29 hrs due to DPR operation. (Type of fault and type of protection operated were not mentioned).  TR not furnished (In place of TR, EL furnished.)  As per EL, line tripped (in 3-ph) at 07:29:50.522 hrs on Relay Definitive Trip/ 86T operation.  As per DR, line tripped (in 3-ph) at 07:29:50.522 hrs on 86T operation.  Time-sync of PR’s with GPS needed to be ensured.

Tripping of 230 kV Villanur – Pondicherry line: Villianur (PED) end:  As per FIR/TR, line was kept holding.  It was stated in FIR/TR that Failure of B-phase 230KV Current Transformer (Make: TELK, Sl. No.:230116- 39, Year of Manufacture: 1985) of HV-I Breaker of 230/110 kV 100MVA Auto Transformer-I at 07:29 hrs on 15.06.2018 due to ageing, resulted in tripping of 230 kV Neyveli-Villianur Line breaker at TS-II, Neyveli and 230 kV Pondy-Villianur Line Breaker at 400 kV Pondy SS. Due to this, supply to 110/ 22 kV substations, viz., Marapalam SS, Venkata Nagar SS, Kalapet SS, and Villianur SS fed from this station got affected. Pondicherry (PGCIL-SR2) end:  As per FIR/DR/EL/TR, line tripped at 07:29:25.733 hrs on B-E fault due to DPR, Z2 (tz2 = 250 msec) operation.

 Remedial action informed by PED:  Failed CT (Year of manufacture: 1985, Year of commissioning:1987) was replaced with Y-phase CT released from 230 kV Pondy-Villianur Line as no spare CT with similar CT ratio 150-300-600-1200/ 1-1-1-1A was available on hand at Villianur SS. Auto Transformer-I was brought back into service at

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 5/8

Annexure-II 19:31 hrs on 15.06.2018.  Six numbers of new 230 kV CTs with CT ratio 300-600-1000-1200-1600/1-1-1-1A have been supplied to this department by M/s PGCIL on 04.07.2018 in lieu of CTs borrowed by them. Actions have been initiated to replace the in-service aged 230KV HV-I & HV-II CTs with the newly supplied CTs to avoid any more failure of 230KV CTs due to ageing.

Deliberations:  It was noted that the triggering fault (CT blast) was within the zone of differential protection of 230/ 110 kV Autotransformer – I (230 kV BBP had been kept out of service at the time of occurrence of this GD). However, non-operation of these primary protections during the incident was suspected/ attributed to the fact that since 110 kV side was radially fed, shorting/ bypassing of the CT from 230 kV side during the incident on account of engulfing arc might have resulted in zero difference current, and their consequent non-operation.

 PGCIL (SR-II) to revise Zone-2 time-setting to 150 msec at Pondy end on 230 kV Pondy - Villianur line.  NLCIL to revise Zone-2 time-setting to 150 msec at NLC TS-2 end on 230 kV NLC TS2 - Villianur line.

The above revised settings would be retained till 230 kV Busbar protection is put into service at 230/ 110 kV Villianur SS, which information would be shared by PED with all concerned.

 When enquired about the type of protection that resulted in 86T operation from NLC TS2 end, NLCIL informed that they would look into the same and revert soon. Since the protection had acted almost instantaneously, NLCIL was asked to take necessary steps to rectify the same and inform the remedial action taken.

 In this regard, PED was also asked to take steps to comply with the protection audit remarks of Villianur SS in a phased and time-bound manner.

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 6/8

Annexure-II Single line diagram of 230/ 110 kV Villianur SS of Puducherry ED (Ref: 1)

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 7/8

Annexure-II

Single line diagram of 230/ 110 kV Villianur SS of Puducherry ED (Ref: 2)

Analysis of Grid Disturbances at Villianur Substation of Puducherry ED 8/8

Annexure-III

Status of Implementation of New Protection Audit Recommendations (as on 20.07.2018)

Puducherry ED

1) 230/ 110 kV Villianur SS [10 - 12 July, 2017]

Sl. No. Deficiences/Nonconformity observed Status of Implementation of Protection Audit Recommendations Remarks

1 Directional O/C & E/F protections to be provided for 230 kV & 110 kV feeders Mail dated 30.01.2018 & 13.03.2018 & 10.07.2018: Pending PSDF where Main-II is not provided; Directional E/F protection to be provided for 230 Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels kV & 110 kV feedes where Main-I & Main-II are provided installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

2 Line CVT's to be provided in all phases for all 230 kV lines. Mail dated 30.01.2018 & 13.03.2018: Pending PSDF As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed)

Mail dated 10.07.2018: A tender has been floated on 15.05.2018 to invite e-tender to replace the existing aged outdoor equipments along with deteriorated RCC supporting structure. Provision has been given to provide Line CVTs in all phases in the fore said tender. The e-tender has been opened and Technical evaluation is under process. 3 Redundant DC suppy for protection (110 V) and communication (48 V) Mail dated 30.01.2018 & 13.03.2018: Pending applications to be provided with requisite segregation in wiring. Existing aged Two sets of 110Volt Station Batteries have been replaced with two sets of new 110Volt Station Batteries. Further, in addition to the existing one set of 48Volt PLCC battery, one more 48Volt PLCC Battery has been provided. All the above three batteries have been commissioned in the last week of January 2018. Wiring has to be done to segregate the existing single circuit into two circuits.

4 For 230 kV feeders, the present single-zone BB protection is to be reviewed and Mail dated 30.01.2018 & 13.03.2018: Pending PSDF provided with two-zone operation & Check-zone operation. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

5 Z4 (reverse) is to be provided in all distance relays of 230 kV & 110 kV feeders Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

6 Z2 and Z3 (reactive & resistive) reaches & time settings were observed to be Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings not in line with Ramakrishna Committee guidelines, which may be reviewed Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. appropriately. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

1/11 Page 1 of 11 Annexure-III

7 Auto-reclosure dead-time and reclaim-time for 230 kV feeders may be revised to Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings 1 sec and 25 sec respectively. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

8 Power Swing Philosophy (Z1 --> Unblock; Higher Zones --> Block for 2 sec) is Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings to be adoped unfiromly across all 230 kV feeders. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

9 Load encroachment feature may be appropriately kept enabled in 230 kV & 110 Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings kV feeders. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

10 For 230 kV Pondy feeder POR may be used in place of the existing PUR. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

11 Steps to be taken to ensure that Main-I & Main-II protections or Main & back-up Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending protections of feeders are fed from different DC supplies. Existing aged Two sets of 110Volt Station Batteries have been replaced with two sets of new 110Volt Station Batteries. Further, in addition to the existing one set of 48Volt PLCC battery, one more 48Volt PLCC Battery has been provided. All the above three batteries have been commissioned in the last week of January 2018. Wiring has to be done to segregate the existing single circuit into two circuits.

12 REF protection to be provided for 100 MVA, 230/ 110 kV ICT-1 & ICT-2. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

13 Directionality to be provided for O/C protection of 100 MVA, 230/ 110 kV ICT-1 Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF & ICT-2. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

14 Directional E/F protection to be provided for 100 MVA, 230/ 110 kV ICT-1 & ICT- Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF 2. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

2/11 Page 2 of 11 Annexure-III

15 Overflux protection to be provided for 100 MVA, 230/ 110 kV ICT-1 & ICT-2. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

16 Steps to be taken to ensure that Group-A & Group-B protections or Main & back- Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending up protections of ICT's are fed from different DC supplies. Existing aged Two sets of 110Volt Station Batteries have been replaced with two sets of new 110Volt Station Batteries. Further, in addition to the existing one set of 48Volt PLCC battery, one more 48Volt PLCC Battery has been provided. All the above three batteries have been commissioned in the last week of January 2018. Wiring has to be done to segregate the existing single circuit into two circuits.

17 At present AC auxiliary supply is being provided from 440 Volt, 3phase, 50 Hz Mail dated 30.01.2018: Pending LT supply from 200 kVA, 22 kV/440 V Transformer connected directly on the Various possible ways to connect the 110/22KV Villianur Sub-Station with nearby 110/22KV Korkadu SS by 22KV main bus of the nearby 110/22 kV Villianur SS. Since this substation is fed from feeder is being explored. 230/ 110 kV Villianur substation, steps may be taken to provide redundant AC auxiliary supply by providing another 200 kVA, 22 kV/ 440 V transformer in the Mail dated 13.03.2018 & 10.07.2018: 110/ 22 kV SS that is charged from 22 kV Korkadu feeder, and laying another Division-EHV of this department has been requested vide Lr. No.714/Ed/EE-Auto SS/AEE-M-VASS/F-4/2017-18, 440 V cable from its secondary to thr AC supply changeover panel at 230/ 110 dated 27.02.2018 (Copy enclosed) to explore the possibilities of providing another 200KVA, 22KV/440V station kV Villianur SS. transformer I nearby 110/22KV Villianur SS that is charged by a 22KV feeder either from 110/22KV Korkadu SS or Kurumbapet SS for providing AC auxiliary supply to 230KV Villianur Auto SS.

18 GPS based time-synchronization equipment may be provided for synchronizing Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF various 230 kV & 110 kV protection relays. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

19 Steps may be to taken provide DR's with facility for automatic fault record Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF downloading to a central PC/ server. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

20 Standalone Event Logger may be provided. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

21 It was observed that existing 100 MVA transformers had not been provided with Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF fire protection. Steps may be taken to provide the same in accordance with the As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of relevant standards. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed)

3/11 Page 3 of 11 Annexure-III

22 It was observed that supporting structures and equipment such as breakers, Mail dated 30.01.2018 & 13.03.2018: Pending PED CT's, isolators, etc. In 110 kV switchyard had served thier full life. Steps may be As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of taken to refurbishing of 110 kV switchyard appropriately. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, replacement of existing deteriorated RCC supporting structures have been proposed to be replaced with G.I. lattice structure.

Mail dated 10.07.2018: A tender has been floated on 15.05.2018 to invite e-tender to replace the existing aged outdoor equipments along with deteriorated RCC supporting structure. Provision has been given to provide Line CVTs in all phases in the fore said tender. 23 Vegetation & weeding was observed in switchyard area. Steps may be taken to Mail dated 30.01.2018: Pending PSDF provide chemically treated PCC flooring, and then covering it with suitable blue As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of metal spreading in switchyard area. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide chemically treated PCC flooring, and then covering it with suitable blue metal spreading in switchyard area.

Mail dated 13.03.2018 & 10.07.2018: Vegetation & weeds grown in the switch yard area were manually cleared and now the switch yard is kept clean. However, as a permanent measure, Detailed Project Report at the cost of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide chemically treated PCC flooring, and then covering it with suitable blue metal spreading in switchyard area.

24 It was observed that most of the existing gantry & equipment supporting (RCC) Mail dated 30.01.2018 & 13.03.2018: Pending PSDF structures are in dilapidated state. Steps may be taken to replace them with As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of suitable lattice/ tubular structures. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to replace the existing dilapidated gantry & equipment supporting (RCC) structures with G.I. lattice / tubular structures.

25 Earth-resistance values for various earth-pits seem to be on higher side. Steps Mail dated 30.01.2018 & 13.03.2018: Pending may be taken to bring it down to less than 1 ohm. Action has been initiated to bring down the earth resistance value to less than 1ohm

Mail dated 10.07.2018: Earth resistance values have been measured in the last total shutdown availed in this station on 30.06.2018. Action has been initiated to bring down the earth resistance value to less than 1ohm 26 Equipment labeling for proper phase-sequence may be provided. Mail dated 30.01.2018: complied Action has been initiated to Equipment labeling for proper phase-sequence

Mail dated 13.03.2018 & 10.07.2018: The work of Equipment labeling for proper phase-sequence was completed on 13.03.2018.

4/11 Page 4 of 11 Annexure-III

27 Earthing of various equipment including door-to-panel earthing to be properly Mail dated 30.01.2018: Complied ensured. Action has been initiated for Earthing of equipment including door-to-panel earthing.

Mail dated 13.03.2018 & 10.07.2018: The work of Earthing of various equipment including door-to-panel earthing was completed on 13.03.2018.

28 Buccholtz relays may be provided with suitable canopy to prevent unwarranted Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending trippings due to moisture ingress. Suitable canopy has been fabricated and kept on hand awaiting for shutdown to provide over Buchholz relays

29 At present, PED is dependent on external agencies for carrying out testing of Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending various electrical equipment & relays & protection oriented trouble shooting. Steps have been initiated to establish Standard Testing Lab and procurement of essential testing equipments to Steps may be taken to establish Standard Testing Lab and procurement of cater to all 230 kV substations. essential testing equipments to cater to all 230 kV substations under its control.

30 PED informed that they had already initiated steps for Renovation & Upgradation Mail dated 30.01.2018: Complied (R&U) of grid stations in Pondycherry region (230/ 110 kV Villianur SS & 230/ Detailed scope of the works included in proposed R & U works has already been furnished vide Lr.256/ED/EE- 110 kV Bahour SS) under PSDF funding, covering most of the above works. In MRT&MMC/F-SRPC/2017-18, dated 14.08.2017. (copy enclosed) this regard, PED is requested to furnish detailed scope of the works included in proposed R & U works. Mail dated 13.03.2018 & 10.07.2018: Detailed scope of the works included in proposed R & U works has already been furnished vide Lr.256/ED/EE- MRT&MMC/F-SRPC/2017-18, dated 14.08.2017. (copy enclosed)

31 In view of radial operation of 110 kV feeders, Zone-1 reach may be increased to Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings 90 % of line length, and Zone-2 time-setting may be reduced to 150 msec. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

2) 230/ 110 kV Bahour SS [10 - 12 July, 2017]

Sl. No. Deficiences/Nonconformity observed Status of Implementation of Protection Audit Recommendations Remarks

1 It is observed that main protections of feeders (230 kV as well as 110 kV) and Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF trasformers are being provided from static relays. Steps may be taken to replace Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels the same with suitable numerical relays. installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

2 Directional O/C & E/F protections to be provided for 230 kV & 110 kV feeders Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF where Main-II is not provided; Directional E/F protection to be provided for 230 Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed kV & 110 kV feedes where Main-I & Main-II are provided with numerical relays under the project of Upgradation of existing static relays and replacement of sub-station equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

5/11 Page 5 of 11 Annexure-III

3 Z4 (reverse) is to be provided in all distance relays of 230 kV & 110 kV feeders Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

4 Z2 and Z3 (reactive & resistive) reaches & time settings were observed to be Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings not in line with Ramakrishna Committee guidelines, which may be reviewed Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. appropriately. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

5 Auto-reclosure dead-time and reclaim-time for 230 kV feeders may be revised to Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings 1 sec and 25 sec respectively. Accordingly Pole Discreancy time-delay may be Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. kept at 1.5 sec. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

6 Power Swing Philosophy (Z1 --> Unblock; Higher Zones --> Block for 2 sec) is Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings to be adoped unfiromly across all 230 kV feeders. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

7 Load encroachment feature may be appropriately kept enabled in 230 kV & 110 Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings kV feeders. Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

8 It is observed that busbar protection relays have been provided for both 230 kV Mail dated 30.01.2018 & 13-03-2018 & 10.07.2018 Pending & 110 kV buses. However, the same have been kept out of service since Co-ordination of Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested to commisssioning. PED shall take steps to put these into operation. bring the 230KV and 110KV Bus Bar Protection scheme into service.

9 For 230 kV Pondy feeder POR may be used in place of the existing PUR. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings Protection & Communication wing of TAN TRANSCO Limited, Villupuram has been requested vide Lr. No.347/ED/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 21.09.2017 for revision of existing relay settings as per the recommendations of Protection Audit Team.

10 Steps to be taken to ensure that Main-I & Main-II protections or Main & back-up Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending protections of feeders are fed from different DC supplies. One set of existing aged 110Volt Station Battery has been replaced with a new battery bank during the last week of January 2018. Action has been initiated for necessary wiring to segregate Main-I and Main-II Protection to fed from different DC source.

11 REF protection to be provided for 80 MVA, 230/ 110 kV Transformers -1 & 2. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

6/11 Page 6 of 11 Annexure-III

12 Directionality to be provided for O/C protection of 80 MVA, 230/ 110 kV Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Transformers -1 & 2. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

13 Directional E/F protection to be provided for 80 MVA, 230/ 110 kV Transformers Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF -1 & 2. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

14 Overflux protection to be provided for 80 MVA, 230/ 110 kV Transformers -1 & Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF 2. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

15 Steps to be taken to ensure that Group-A & Group-B protections or Main & back- Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending up protections of Transformers are fed from different DC supplies. One set of existing aged 110Volt Station Battery has been replaced with a new battery bank during the last week of January 2018. Action has been initiated for necessary wiring to segregate Group-A and Group-B Protection of Transformer fed from different DC source.

16 GPS based time-synchronization equipment may be provided for time- Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF synchronizing various 230 kV & 110 kV protection relays. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

17 Steps may be to taken provide DR's with facility for automatic fault record Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF downloading to a central PC/ server. Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

18 Stand-alone Event Logger may be provided. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF Existing Control & Relay Panels installed with static relays are proposed to be replaced with new control panels installed with numerical relays under the project of Upgradation of existing static relays and replacement of substation equipments at 230KV Villianur and Bahour Auto Sub-Station at the cost of Rs.10,56,16,191/- through PSDF funding. Tendering process for award of work on labour contract basis for the above said work is almost over and waiting for the approval of Puducherry Government to place order at the lowest tenderer.

7/11 Page 7 of 11 Annexure-III

19 Line CVT's to be provided in all phases for all 230 kV lines. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide Line CVTs in all phases for all 230KV Lines..

20 Surge Arrestors to be to be provided for 230 kV feeders at gantry entry point. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide Surge Arrestors for 230KV feeders at gantry entry point.

21 Oil leakage is being observed in both 80 MVA, 230/ 110 kV Tranformers. Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PED Suitable action may be taken to arrest the same. Budgetary offer has been called for from a reputed contractor for arresting oil leakage observed in the Transformers. Work will be commenced shortly on obtaining expenditure sanction from the competent authority on the estimate prepared with the rate offered by the contractor.

22 It is observed that existing 80 MVA transformers have not been provided with Mail dated 30.01.2018 & 13-03-2018: Pending PSDF fire protection. Steps may be taken to provide the same in accordance with the recommendation of Protection Audit Team, a Detailed Project Report at the cost of Rs.14,85,42,653.21 has relevant standards. been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide fire protection system to 80MVA Auto Transformer-I&II.

Mail dated 10.07.2018: As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide fire protection to transformers.

23 It is observed that 230 kV & 110 kV Bus-Coupler breakers are not in working Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF condition, and have been kept out of service. Also they have no attendant CT's. OEM M/s.Crompton Greaves Limited has been requested to offer rate to bring back the 230KV Bus Coupler PED may therefore take steps to replace them with attendant CT's to make way Breaker into service. As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost for two-zone busbar protection. of Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide attendant CTs to make way to two-zone busbar protection.

24 Segregation in wiring for extending supply from DC1 and DC2 to trip coils of 230 Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending kV & 110 kV feeders to be carried out. Action has been initiated to segregate the wiring for extending supply from DC1 and DC2 to trip coil of 230KV and 110KV Breakers.

8/11 Page 8 of 11 Annexure-III

25 Redundant DC suppy for communication (48 V) application to be provided with Mail dated 30.01.2018: Complied requisite segregation in wiring. In addition to the existing 48Volt PLCC battery, one more 48Volt PLCC Battery bank has been erected and commissioned during the last week of January 2018. Wiring will be done to segregate Source-1 & II.

Mail dated 13.03.2018 & 10.07.2018: In addition to the existing 48Volt PLCC battery, one more 48Volt PLCC Battery bank has been erected and commissioned as a redundant DC supply for communication during the last week of January 2018 with requisite segregation in wiring.

26 All gantry towers (metallic structures) including lightning masts to be earthed Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending properly as per relevant standards. Action has been initiated to earth all gantry towers (metallic structures) including lightning mast.

27 Equipment labeling for proper phase-sequence may be provided. Mail dated 30.01.2018: complied Action has been initiated to Equipment labeling for proper phase-sequence

Mail dated 13.03.2018 & 10.07.2018: The work of Equipment labeling for proper phase-sequence was completed on 13.03.2018.

28 Door-to-panel earthing in various switchyard marshalling panels to be properly Mail dated 30.01.2018: complied ensured. Action has been initiated for Earthing of equipment including door-to-panel earthing.

Mail dated 13.03.2018 & 10.07.2018: The work of Door-to-panel earthing in various switchyard marshalling panels was completed on 13.03.2018.

29 Buccholtz relays may be provided with suitable canopy to prevent unwarranted Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending trippings due to moisture ingress. Suitable canopy has been fabricated and kept on hand awaiting for shutdown to provide over Buchholz relays

30 At present AC auxiliary supply is being obtained from 22 kV Bahour Mail dated 30.01.2018: Pending (Pandasozhanallur) feeder from nearby 110/ 22 kV Bahour SS. Since this 110/ Exploring all the possible ways to provide another dedicated redundant AC auxiliary supply from nearby 22 kV SS is being fed from the present 230/ 110 kV SS, in the event of supply 110/22KV Sub-Station which is being fed by other 230KV Sub-Stations. failure at the latter, the former will also lose supply. PED shall take steps to provide another dedicated redundant AC auxiliary supply feeder. Mail dated 13.03.2018 & 10.07.2018: Division-EHV of this department has been requested vide Lr. No.714/Ed/EE-Auto SS/AEE-M-VASS/F-4/2017-18, dated 27.02.2018 (Copy enclosed) to explore the possibilities of arranging an alternate 22KV supply fed from 110/22KV Sub-Stations those are either fed from 230KV Villianur Auto SS or 230KV Thondamanatham Auto SS for the existing 22KV/440V Distribution Transformer installed in the campus of 230KV Bahour Auto SS, presently being fed by 22KV Pandasozhannlur feeder from 110/22KV Bahour SS.

31 DC earth leakage is being observed in both 110 V DC Sources. Also the Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending corresponding DC Earth-fault relays in soruce end DCDB panels are observed to DC earth leakage being observed in the battery charger will be attended in the forthcoming total shutdown. be not in working-condition. Steps shall be taken to rectify the same at the Replacement of existing DC Distribution Panels have been included in the DPR. earliest.

9/11 Page 9 of 11 Annexure-III

32 Vegetation & weeding is observed in switchyard area. Steps may be taken to Mail dated 30.01.2018: Pending PSDF provide chemically treated PCC flooring, and then covering it with suitable blue As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of metal spreading in switchyard area. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to provide chemically treated PCC flooring, and then covering it with suitable blue metal spreading in switchyard area.

33 It is observed that most of the existing gantry & equipment supporting Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PSDF structures have been of RCC. PED may take steps to replace them with suitable As per the recommendation of Protection Audit Team, a Detailed Project Report at the cost of lattice/ tubular structures when R & M works for the substation are propsoed. Rs.14,85,42,653.21 has been prepared to replace the existing aged equipments and provide additional equipments at 230KV Villianur and Bahour Auto Sub-Station and sent to higher authority to obtain sanction under PSDF funding. (copy enclosed). In that DPR, provision has been given to replace the existing dilapidated gantry & equipment supporting (RCC) structures with G.I. lattice / tubular structures.

34 Testing of various relays and measurement of earth-resistance values for Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending various earth-pits should be undertaken periodically as per relevant standards, Actions have been initiated for Testing of various relays and measurement of earth-resistance values for various and records properly maintained. earth-pits periodically as per relevant standards and record them properly

35 It is observed that relay settings for various protection relays have been set by Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending Settings TNEB at the time of commissioning. However, records relating to the same have Protection and Communication wing of TAN TRANSCO Limited, Villupuram has been requested to furnish the not been made available to PED. Steps may be taken (by PED/ TNEB) to existing relay settings for future reference. maintain proper records w.r.t. Implemented relay settings at Substation level.

36 At present, PED is dependent on external agencies for carrying out testing of Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Pending PED various electrical equipment & relays & protection oriented trouble shooting. Steps have been initiated to establish Standard Testing Lab and procurement of essential testing equipments to Steps may be taken to establish Standard Testing Lab and procurement of cater to all 230 kV substations. essential testing equipments to cater to all 230 kV substations under its control.

37 PED informed that they had already initiated steps for Renovation & Upgradation Mail dated 30.01.2018: Complied (R&U) of grid stations in Pondycherry region (230/ 110 kV Villianur SS & 230/ Detailed scope of the works included in proposed R & U works has already been furnished vide Lr.256/ED/EE- 110 kV Bahour SS) under PSDF funding, covering relay & control panel MRT&MMC/F-SRPC/2017-18, dated 14.08.2017. (copy enclosed) replacement works. In this regard, PED is requested to furnish detailed scope of the works included in proposed R & U works for the 230/ 110 kV substation. Mail dated 13.03.2018 & 10.07.2018: Detailed scope of the works included in proposed R & U works has already been furnished vide Lr.256/ED/EE- MRT&MMC/F-SRPC/2017-18, dated 14.08.2017. (copy enclosed)

38 PED has not provided the following data as part of protection audit: Pending Settings

(i) Fault level of the Substation for 3-ph-Ground and 1-ph-Ground faults at both Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: 230 kV and 110 kV levels Fault level of the station has been requested from EHV division of this department. Details will be furnished as soon as received from the said division.

10/11 Page 10 of 11 Annexure-III

(ii) Adopted Relay Settings (given by Head Quarters/ Corporate Office and Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: implemented in field) Protection and Communication wing of TAN TRANSCO Limited, Villupuram has been requested to furnish the existing relay settings. Relay settings will be furnished as soon as received from the said corporation.

(iii) Details on Periodicity of Relay Testing and latest Relay Test Reports Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Details are being collected from the source available at 230KV Bahour Auto Sub-Station. Details will be furnished shortly.

(iv) Details of Measurement of Station Earth-Mat & Earth-Pits Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Action has been initiated to measure the Earth-mats and Earth-Pits value. Measurements will be submitted shortly.

(v) AC Supply Changeover Scheme Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Will be submitted shortly.

(vi) Details of 110 kV CT's Ratios and Errors Mail dated 30.01.2018, 13.03.2018 & 10.07.2018: Details have been called for from TAN TRANSCO Limited. Will be submitted shortly on receipt of the same.

11/11 Page 11 of 11 Annexure-IV

Compliance Status of the Recommendations given in the Special Meeting on Neyveli GD held on 03.01.2017

Sl. Recommendation Puducherry ED (furnished vide their NLCIL (furnished vide their mail TANTRANSCO No. mail dated 10.07.2018) dated 13.10.2018) (furnished vide their mail dated 23.02.2017) 1 Provision of GPS/ Time 1. Existing Control & Relay panels In order to provide GPS connectivity Tender has been opened for synchronization facility in all installed with static relays are to numerical relays of Generator and provision of GPS, DR & EL and 220 kV & above substations/ proposed to be replaced with new feeder, OEM of relay and probable procurement is under progress. generation switchyards control panels installed with suppliers were addressed. M!s. ABB, [PED, TANTRANSCO, numerical relays under the project OEM of GRP relays, after exten sive fi [PENDING] NLCIL, ST-CMS] of PSDF in both 230KV Villianur eld study informed that Time and Bahour Auto Sub-Stations. Synchronisation facility is not possible Tendering process for award of fo r the old version relays in service at work on labour contract basis for TPS-1. the above work is almost over and awaiting for the approval of TPS 1 is likely to be phased out within Puducherry Government to place a year. All the connected 220KV order to the lowest tenderer. feeders emanating from TPS 1 2. A tender has been floated on Switchyard will be diverted to the 15.05.2018 to invite e-tender to upcoming TANGEDCO 230/ 110 KV SS replace the existing aged outdoor near NNTPP. In view of the above and equipments along with considering the remaining life period deteriorated RCC supporting of TPS 1 , the proposal to implement structure in the above said GPS connectivity is under scrutiny for substations. The e-tender was in principle approval. opened and Technical evaluation is under process. However, built-in clocks of 220KV 3. In the event of completion of the feeder protection relays are being above said works, both of the updated periodically, using a Laptop substations would be equipped whose system clock is set to GPS with GPS / time synchronization time. Considering the phasing out facility. proposal of TPS 1 from April 2019, 220KV feeders at TPS 1 may be [PENDING] exempted from implement at ion of GPS time synchronisation facility. [PENDING w.r.t. NLC TS2] Page 1 of 5 Annexure-IV

2 TANTRANSCO was The Digital Events (Breaker status) is recommended to get the programmed for RTU time stamping functionality (including and the same was tested in Alundur power supply) of the DCPC’s and Trichy 230 kV Sub-Stations. [between MLDC and [PENDING] Tiruvannamalai/ Villupuram/ NLC TS-I/ During the tripping of the generation ST-CMS] checked and Unit-B on 25-11-2016 (17:27:09 hrs) ensure their healthiness all in O/C protection and subsequent the time. [TANTRANSCO] tota l generations/ feeder tripping, the 4BV, BOA Carrier 3 Migrating to RTU time- [PENDING] [PENDING] Communication charger AC fuse stamped SoE at the stated failed (maintained by NLC) and 4BV, stations/substations 100Ah battery source drained due to [Bahour, Villianur, NLC TS-II, aging (DoC of Battery was 1996 & NLC TS-I, ST-CMS, Alundur, served for more than 20 years) and Trichy, Tiruvannamalai, all Voice & data channels through Villupram, Singarapet and PLCC equipments at Neyveli TS-I, Deviakurichi] (Viz., Cuddalore, T.V.Malai and Villupuram and ST_CMS PLCC in TS-I [PED, TANTRANSCO, & II link feeder) disturbed and no NLCIL, PGCIL (SR-II)] data migration from their respective RTUs to DCPC equipment reporting to MLDC Chennai.

It is also noted that there is no redundant OFC path ready for data migration to Back-up Control Center at Madurai LDC through Kadalangudi, Thiruvarur towards Trichy provided by PGCIL/Tejas Ltd. under fiber expansion project for ULDC scheme. However as per the ULDC up-gradation scheme, data through Neyveli DCPC (Main & Stand-by) are configured in such a

Page 2 of 5 Annexure-IV

way to report to MLDC SCADA at Chennai.

M/s.PGCIL/Tejas Ltd. will be informed to test and commission the OFC link between Neyveli and Trichy through Kadalangudi, Thiruvarur,Thanjavur & Trichy to extend the communication channel for ULDC SCADA Back-up Control Center at Madurai. [PENDING]

4 Review settings adopted for Reviewed O/C protection and other [COMPLIED] relevant protections for Unit-8. [NLCIL]

5 NLCIL was recommended to Settings recommended by M/s BHEL- check integrity of Static EDN (OEM), are adopted for Static Excitation System of Unit-1 Excitation System in all the 9 Units of for proper operation. OEM’s TPS 1. help may also be taken in [COMPLIED] this regard, if required. [NLCIL] 6 Review of AVR’s excitation In order to ascertain the integrity of limiter settings of all SES of UNIT-1, a committee with generating Units three senior executives of NLCIL was appropriately at NLC TS-I so constituted. The committee that unwarranted tripping of scrutinised the SES settings in all generating Units is aspects and conducted necessary prevented in fit-cases where field tests. OEM was also consulted GT/ ICT/ feeder O/C during the study. The committee has protections could have stated that the adopted settings are acted first. OEM’s help may intact. also be taken in this regard, [COMPLIED] Page 3 of 5 Annexure-IV

if required. [NLCIL]

7 Puducherry was Total shutdowns are being availed recommended to take periodically at 230KV substations in appropriate steps for Puducherry Electricity Department attending to suspected hot- and carried out maintenance works to spots in time, which is also avoid any breakdown due to hot- mandated as per Regulation spots. 26 of CEA (Grid Standards) Regulations, 2010. [PED] [COMPLIED]

8 TANTRANSCO was Procurement of Thermo-vision recommended to provide at Camera is under progress. least one more thermo- vision scanning camera so [PENDING] that each circle would have their exclusive thermo- vision scanning camera to attend to hot-spots in time. [TANTRANSCO]

9 Puducherry was Load to the tune of 67 MW being so recommended to carry out for availed from 230 kV Villianur Auto load-rearrangement by Sub-Station by 110/22 kV shifting some loads from Kurumbapet Substation was Bahour/ Villianur to transferred to 230KV Thondamanatham and Thondamanatham SS on 13.04.2018. distribute them more evenly Now, load at all three 230KV across these substations. substations are at evenly distributed. [PED] [COMPLIED] 10 TANTRANSCO was It is prudent to maintain the open recommended to undertake condition of Acharapakkam holistic review of all such Villupuram feeder to avoid the tripp lines, which are mostly kept ing of 230 KV Maps - Achrapakkam open (like Acharapakkam – feeder on overloading. Otherwise if Page 4 of 5 Annexure-IV

Villupurram, Alundur – the feeder is tripped, 230 KV MAPS - Algarkoil, Kadalangudi – Echur, SPDR - Arni & MAPS - S.P.Koil Tiruvaroor) for suitable # 1 & 2 feeders trip cascadingly on system strengthening overload. Also, MAPS units will pull measures, and implement out, the cascade disturbance would them in a phased manner in have been imparted to certain areas the interest of grid security of Chennai city i.e. S.P.Koil, and operational flexibility. Oragadam, Siruseri & Arni. Similarly, [TANTRANSCO] the open condition of Alundur - Alagarkoil feeder have saved the cascaded tripping in Madurai, Pugalur and Myvadi areas during the recent disturbance. [COMPLIED]

However, review will be done in a phased manner for suitable system strengthening measures for ensuring Grid security. [PENDING]

11 Furnishing of tripping details Tripping events are being uploaded by COMPLIED The Tripping details are being in compliance of Regulation Puducherry Electricity Department in furnished then and there in the 5.2 (r) of IEGC SRLDC’s web-portal within 24hours of POSOCO website. [PED, TANTRANSCO, occurrence. NLCIL, PGCIL (SR-II)] [COMPLIED] [COMPLIED] [COMPLIED]

*****

Page 5 of 5 Annexure-V

Special Meeting on Pending Protection Issues of Puducherry Substations

20-07-2018

Page 1 of 13 Annexure-V

Complete outage of 230kV Villianur substation

• Failure of switchyard equipment leading to complete station outage

• Delayed clearance of fault

• Non operation of primary protection at Villianur station

• Load Loss in Pondicherry control area > 100MW (each time)

Page 2 of 13 Annexure-V

Complete outage on 30.05.2018

Event Details of tripping Remedial actions taken Points for discussion by Puducherry Complete outage of 230KV Failure of R-phase 230KV CT of Failed CT replaced with R-phase Non-operation of protection at Villianur Sub-Station 230/110KV 100MVA ICT-2 at 230KV CT from 230KV Pondy-Villianur Villianur at 08:40hrs on 30.05.2018 Villianur Station. Line. Auto Transformer-II brought back into service on Action plan for replacement 230KV Neyveli-Villianur and 230KV 31.05.2018. plan of CT’s for 230KV HV-I & Pondy-Villianur lines tripped from HV-II CT’s Neyveli end and Pondicherry end One set of new CT’s (CT ratio respectively. This led to loss of 400-800-1000-1200-1600/1A) Bus bar protection out of supply to 230KV Villianur Station. were erected in Pondycherry service line bay on 31.06.2018.

Fault clearing time – 360ms Bus bar protection taken out of service

Actions initiated to replace the in service aged 230KV HV-I & HV-II CTs with the newly supplied CTs. (Six numbers of new 230KV CTs with CT ratio 300-600-1000-1200-1600/1A)

Page 3 of 13 Annexure-V

Complete outage on 05.06.2018

Event Details of tripping Remedial actions atken Points for discussion by Puducherry Complete outage of 230KV Failure of B-phase pole of breaker 1. Failed Kalapet feeder CB was Healthiness status of Villianur Sub-Station at of 110KV Villianur – Kalapet line at replaced with spare new CB. CT’s remaining equipments in 11:23hrs on 05.06.2018 Villianur end of Kalapet feeder replaced with 132kV switchyard new CT’s as a precautionary measure. Switchyard earth resistance HV & LV back up over Current relays higher than permissible limits. of both Auto Transformer-I & II 2. Provision of 4sets of pipe in acted for R, Y & B-phase. Protection pipe chemical earthing at the DC failed as the terminal fuse of back yard of control room 110 Volt Station Battery bank. 3. Switch yard earthing 230KV Neyveli-Villianur and 230KV measurement (30.06.2018). Pondy-Villianur lines tripped from Individual and combined earth Neyveli end and Pondicherry (zone- pit value of Kalapet feeder bay – 3) end respectively. 3 ohm.

Fault clearing time – 720ms Other earth pit values observed on higher sides, actions initiated to strengthen earthing of switch yard.

Page 4 of 13 Annexure-V

Complete outage on 15.06.2018

Event Details of tripping Remedial actions atken Points for discussion by Puducherry Complete outage of 230KV failure of B-phase 230KV Current Failed CT replaced with Y-phase Reason for non-operation of Villianur Sub-Station at Transformer (Make: TELK) of HV-I CT from 230KV Pondy-Villianur protection at Villianur. 07:29 Hrs Breaker of 230/110KV 100MVA Line. Auto Transformer-I on 15-06-2018 Auto Transformer-I at Villianur brought back into service on Action plan for replacement substation 15.06.2018. plan of CT’s for 230KV HV-I & HV-II CT’s 230KV Neyveli-Villianur and 230KV One set of new CT’s (CT ratio Pondy-Villianur lines tripped from 400-800-1000-1200-1600/1A) Bus bar protection out of Neyveli end and Pondicherry (zone- were erected in Pondycherry service 2) end respectively. line bay on 31.06.2018.

Bus bar protection taken out of Fault clearing time – 350ms service

Actions initiated to replace the in service aged 230KV HV-I & HV-II CTs with the newly supplied CTs. (Six numbers of new 230KV CTs with CT ratio 300-600-1000-1200-1600/1A)

Page 5 of 13 Annexure-V 1. Complete Outage of 230kV Villianur station at 08:42 Hrs on 30-05-2018

• Triggering Incident: Failure of R-ph CT of HV side 100MVA 230/110kV transformer 2. • Transformer protection did not operate. • Following feeders tripped: • 230kV NLC st-2 - Villianurtripped at NLC end on over current protection. • 230kV Pondy - Villianurline tripped at Pondy end on zone 2 distance operation.

• Load loss: 130 MW

Page 6 of 13 Annexure-V PMU Plots:

Dip in B-phase voltage indicate fault in B- phase.

Fault Clearance time: 360 msecs

Page 7 of 13 Annexure-V SLD of 230kV Villianurstation

Page 8 of 13 Annexure-V 2. Complete Outage of 230kV Villianur station at 11:23 Hrs on 05-06-2018

Villianur end

• Triggering Incident: Failure of R-ph breaker of 110kV Kalappet - Villianurline at Villianur end. • Fault was cleared by tripping of the upstream feeders. • Following feeders tripped: • 230kV NLC st-2 - Villianurtripped at NLC end on Z3, distance protection. • 230kV Pondy - Villianurline tripped at Pondy end on Z3 distance protection. • Load loss: 120 MW Page 9 of 13 Annexure-V PMU Data Plots

Dip in B voltage was observed in all the phases of 400kV Sriperumpudur bus during the event for 720ms.

Remedial measures taken:

Terminal fuse of 110V battery bank replaced.

Page 10 of 13 Annexure-V SLD of 230kV Villianurstation

Page 11 of 13 Annexure-V 3. Complete Outage of 230kV Villianur station at 07:29 Hrs on 15-06-2018

• Triggering Incident: B-phase CT (Make: TELK) of HV-I Breaker of 230/110KV 100MVA Auto Transformer-I got failed • Fault was cleared by tripping of the upstream feeders. • Following feeders tripped: • 230kV NLC st-2 - Villianurtripped at NLC end on operation of 86T. • 230kV Pondy - Villianurline tripped at Pondy end on distance protection zone 2.

• Load loss: 102 MW

Page 12 of 13 Annexure-V PMU Plots:

Dip in B voltage was observed in 400kV Sriperumpudur bus during the event for 350ms.

Page 13 of 13