Observations/Remarks. Sl. No.

Transcription

1 Name of Substation Date of Audit Observations/Remarks 00kV Thrichy SS..0 The old electromagnetic/static relays may be replaced with numerical relays. The possibility of testing relays as per schedule may be explored. Existing 0 V set- Batteries may be enhanced to adequate capacity. It was informed that action has been initiated. 00kV Salem SS(IS)..0 The existing static distance protection relays of 00 kv feeders may be replaced with numerical relays 0kV Madurai SS..0 Possibility of providing time synchronising system (GPS unit) for protection relays. The existing static distance protection relays to be replaced with numerical relays. Dedicated Event logger may be provided for post tripping analysis. The existing KVA DG set may be enhanced to 0 KVA. An additional V battery set may be provided for reliable PLCC operation. The partially damaged RCC equipment support structure may be attended on urgent basis. 0kV Pugalur SS 0..0 Possibility of providing CB for sectionalised bus may be explored. DG set capacity may be enhanced to 0 KVA from KVA by providing additional KVA DG set. Fire extinguisher system of the power transformer may be enhanced. GPS system may be installed for synchronising relays. Better protection infrastructure facilities like Event Logger Disturbance Recorder with dedicated computer systems, printers (As of now only one system available). 0kV Kundah-(Gen) kv GC Breaker may be erected and commissioned urgently to avoid tripping of tie feeders in the event of tripping of auto transformers 0kV Kundah-(Gen).0.0 sets of Las have been provided at bus only. Second core of Bus VT has been used for line protection. Line CVTs are only for synchronising purpose. 0kV Pykara Ultimate SS(Gen).0.0 DC leakage observed in the station. Yet to be attended. 0kV Tudiyalur SS kV Warangal SS kV Ramagundam SS(IS), &.0.0 Distrubance Recorders (ABB, INDACTIC) not having GPS time synchronisation (for 00 kv Warangal Line, 00 kv Gajwel Line, 00 kv Malkaram Line, 00 kv Hyderabad Line #, 00 kv Hyderabad Line # ), 00 kv Dichipalli Numerical relay (DR) not having GPS time synchronisatiion. Distrubance recorder of 00 kv Nagarjunasagar- sent for repair. However, built-in DR available with the relay MICOM. DC supply-ii: +ve to Earth voltage measured is V, -ve to Earth voltage measured is -0 V. Over current & earth fault protection enabled in Chandrapur - & and N'Sagar & as per instructions of NTPC CC (Mail copy verified) CT ratio test results for Dichipalli (Tie & Main), Auto- (Main & Tie), Auto- (Main & Tie), Hyderabad- (Main & Tie), Hyderabad- (Main & Tie), Warangal (Main & Tie), Main & Tie Cts of Gen-, Gen-, Tie-, Tie- will be submitted to SRPC, Bangalore by NTPC Ramagundam subsequently. CVT test results for Warangal, Auto-,, & and Hyderabad & will be submitted to SRPC, Bangalore by NTPC Ramagundam subsequently. NTPC Ramagundam has confirmed that copy of recommended/adopted relay settings for all the feeders will be submitted to SRPC, Bangalore subsequently. Time synchronising system (GPS), Distrubance Recorder (DR), Event Logger (ER), Synchro check relay not available in the station.

2 00kV Neyveli TS-II SS O/V protection for stage-ii may be considered for instantaneous trip nd source for V PLCC battery system may be considered. Record of relay setting approved by competent authority is to be made available 00kV NeyveliTS-II Expn Ss Switchyard, control room and battery room are maintained neatly. However, the access way to the battery bank- is found with dumped store material. Replacement of rushed cable trays in the switchyard duct is under progress. One set of Siemens make SF CT in 00 kv for Pondy feeder has been installed with gas monitoring facility. Test reports and registers for periodical testing of relays, equipment and earth mat are maintained properly. Separate auto-reclose relays are available for all the feeders except 00 kv Pugalur-I feeder which has the built-in auto-reclose facility in the numerical relay on selection of Main-I and Main-II. Siemens network client for monitoring the relay settings and actuation with disturbance and event recorder (Siemens DIGSI software) is available. All the relays including the front panel can be viewed from the operator's desk. Oil leak was noticed on ICT- & ICT-. The record of relay settings approved by competent authority to be made available. Efforts hall be taken for arresting oil leak on ICT- & ICT-. The view of NLC in regard to 00 kv auto reclosing scheme and UFR review is received and enclosed. 00kV NeyveliTS-I Expn Ss Switchyard equipments and yard maintained neatly. Relay panel and battery rooms are maintained properly Available GPS clock not synchronised with the protective relays Setting approval for the relays not available Test report documents are only in hand written register Only one black of V battery for PLCC is available. As dedicated Event logger for switchyard events not in service, the events are logged with GPS time stamping in Main plant ABB make DCS, Separate A/R (static) relay from M & M protections is found in use. The inbuilt A/R facility available in M protection is found not used. GPS time to be synchronised with the protection system. Existing micro mho distant protection (Main I) relays to be retrofitted with numerical relays. Record of relay setting approved by competent authority is to be made available Periodical testing of all the relays and switchyard equipments to be done - there is no test record for a few relays/equipments after commissioning 0kV Tandur Ss(IS).0.0 Diesel set has to be commissioned. APTRANSCO should have two independent DC sources to the protection and switchgears and one source should be for back up. Carrier aided protection scheme has to be implemented.

3 & 00kV Mamidipalli SS & 0kV Mamidipalli SS.0.0 The 00 kv and 0 kv Line Panels, Main-I (ABB REL00) and Main-II (ABB RAZFEE) relays are to be replaced by the latest version numerical relays for the following reasons: a) The existing relays are very old. The manufacturer has stopped production and services. b) DR facility is not available in the existing relays. c) REL 00 relay will not show the distance of fault sometimes. d) The DEFR protection has to be enabled in any one of the relays (Main-I or Main-II) as per CBIP guidelines, but they cannot be initiated with the existing relays. Need to adopt uniform protection philosophy. Event logger is not available for 00 kv feeders. Carrier aided protection is not implemented for some of the 0 kv feeders. The existing old analog meters in the control room are to be replaced by Digital Meters (for critical parameters). Remote analog temperature indicators are to be replaced with digital meters. Adoption of different parameters (R&X) for transmission lines using same conductor by APTRANSCO and Power Grid. This requires fresh look as it affects the Zone-, Zone-II and Zone-III distance protection scheme for transmission lines. Closed circuit cameras may be arranged at strategic points inside the switchyard as well as along the fencing of the substation to monitor any critical situation insie and to keep vigilance on outside elements for taking view of changing security threat perceptions to substation. 00kV Nellore SS(IS) 9, kv Nellore SS 9, kV Simhapuri SS kV Meenakshi SS.0.0-0kV T.K.Halli SS 0..0 To provide Bus bar protection for 0kV Bus system at the earliest. To provide GPS synchronisation for 0kV protection system. All the elements in the yard and earthing may be identified. 0kV Subramanyapura SS 0..0 To provide Bus bar protection relays for 0kV system. To provide GPS synchronised system for 0kV protection. 0kV Kadakola SS(IS) 0..0 Recommended to put 0 kv busbar protection system in service at the earliest possible. Recommended to provide time synchronising system (GPS) for protection system. 0 kv Vrushabavathi S/S kv Lines provided with Main I only, Main II protection to be provided. GPS not available, to be provided for time synchronisation. 00kV Jundal SS The over voltage stage - and stub protection functions for 00 kv lines may please be 0..0 enabled for better protection schemes.

4 00kV Guttur SS 0..0 Eventlogger and Time synchronisations facilities are not available. 00kV Hiriyur SS kV STCMS SS(Gen) kV PP Nallur SS(Gen) kV Kalpakkam SS(Gen) kV Shamshabad SS 0..0 ICT- differential, bus bar relays and some of 0 kv lines distance relays are static type relays and are not having the disturbance recorder facilities and hence replacement of the same with numerical type relays may be examined as there is no separate DR facilities. Condition based maintenance like Capacitance & tan delta, Leakage Current Monitoring of Las, DGA, DCRM tests of switchyard equipments may be carried out as per the requirements. SOTF time delay has observed high and same may be examined as per the requirements. The record of CT & CVT ratio test results for old bays which was commissioned in 99 are not available and hence measured values and error calculation for CT & CVT is not mentioned for some base in the format. Atmospheric conditions as specified by the manufaturers of relays may be maintained for smooth operation of relays like cooling system which is observed insufficient. Station is generally found to be in order Replacement of the following static relays by numerical relays may be examined a) Distance relay type LZ9 ABB make b) Busbar protection relay The audit is found beneficial to ST-CMS to confirm about the integrity of the protection functions and maintenance of test records. ST-CMS felt that advance written information may be given before conducting such audits Switchyard, battery room, control rooms are maintained neatly. Most of the records & commissioning reports are available & furnished. The test reports of CT, CVT & CB are to be furnished. The stability test conducted was confirmed orally however no records could be verified Synchronizing relay details to be furnished. Latest Tested dates of Line protection Relays MI, MII, LBB & PLCC are to be furnished Line Parameters for Acharpakkam & Bhavini are yet to be furnished. Recommended line protection relay settings with the latest fault levels and the adapted settings could not be verified. The revised recommendations & copy of adapted relay settings to be submitted by MAPS, NPCIL The Line CVT in the Y phase of the feeder was not available in all the feeders except SP koil : To be reviewed The pending details will be submitted shortly by MAPS, NPCIL. Bus bar protection is not available and in turn there is no LBB protection for circuit breakers. The older version Main- relays (REL-*) for both 0 kv feeders may be replaced with upgraded versions for quick analysis of the faults and access to the relay configuration. Only one set of 0 v battery bank is available. 00 MVA PTR- remote temperature indicator is not functioning. 00 MVA PTR- LV over flux relay is not available.

5 0kV HAIL SS 0..0 Earth leakage observed, the same may be rectified. 0kV Shapoornagar SS 0..0 Over flux relay is to be provided on HV side of 0/ kv, 00MVA PTR, 0 MVA PTR &. Carrier aided protection scheme has to be implemented. Precommissioning test reports of CT & CVT are not available to record the percentage ratio error & ratio measured. & 00kV Malkaram SS & 0kV Malkaram SS kV ITPL SS 0..0 DC Main battery, +ve ground is observed & the same may be rectified. The distance protectio-main-i and Main-II and busbar protection - periodic testing not conducted so far from commissioning. The same may be tested immediately for the healthyness of the above system. PLCC / Protection Coupler not in service. The same may be put into service. 0kV Hoody SS..0 Main-II relays not available in all 0 kv feeders. The same to be provided. PLCC / Protection Coupler not provided in all 0 kv feeders. The same to be provided. CVT not provided in all phases of all feeders in 0 kv feeders. The core CTs are provided in 0 kv feeders. The same may be replaced with core CTs. 00 kv Hoody SS..0 Main-II protection not provided in 0 kv feeders instead Backup protection are provided. Protection Couplers are not provided in the 0 kv feeders. Busbar protection is not provided in the 0 kv systems since old and new stations share the common 0 kv Bus & CT's of the old station do not have separate core for Busbar protection. 9 0kV Sriperumbudur SS.0.0 Static THR relay - Main-II Vallur - I & II feeder has been replaced - retrofitted with REL 0 N relay. Because of i) Ma-operation of Zone- and Faulty. Ii) Mal-operation of Zone- and Zone- and Zone-, tripping time delay might be kept uniform throughout all feeders at Sriperubudur. (Other Main Zone- other Zone tripping including the reverse sign is not uniformly adjusted and to be reviewed.) 0 & 00kV kalavindapattu SS(IS) & 0kV kalavindapattu SS kv feeder Zone- and Zone- trip timings are 0 m sec and 00 m sec. where as in TNEB it is 0 m sec and 00 m sec. This may be looked into. 00kV Vallur SS.0.0-0kV Areakode SS 9..0 The existing Main- (Electrostatic Quadramho) Distance Relays should retrofitted with latest version Numerical Relays for easy and quick analysis of the faults. Over flux protection is not available 0/0 kv, 0 MVA Transformer. Possibility of using separate DC Sources for Main- & Main- may be explored for reiability of DC supply. 0kV Kaniyampeta SS 0..0 Bus bar protection is not available. The 0 kv line's Main I (Electrostatic QUADRAMHO) Distance Relays should retrofitted with latest version Numerical Relays for easy and quick analysis of faults. DG Set is not available. Only one set of Battery charger and battery set is available.

6 0kV Mettur TPS SS(Gen).0.0 Both Main-I and Main-II protection schemes are fed from one DC source. Periodically DC source is switched manually to second DC source. No protection coupler available for MTPS-Stage-III and MTPH feeders. Synchronisation cores of Line VT and Bus VT are of different voltage ratios. Time synchronization facility for global common timer reference is not available at the substation which is given in CEA (Measures relating to Safety and Electric Supply) Regulations, 00 under section, clause -(viii). On 0 kv feeders except MTPS-Stage-III feeder, Main-II relays are of static type, but as per CEA (Technical Standards for Connectivity to Grid) Regulations, 00 under Part-III, Section-, both Main-I and Main-II distance relays are to be of numerical type. 0kV Gobi SS 0..0 As neutral bushing CT is not available for Auto transformer, REF protection is not made available. Time synchronization facility for global common timer reference is not available at the substation which is given in CEA (Measures relating to Safety and Electric Supply) Regulations, 00 under section, clause -(viii). On 0 kv feeders except Arasur feeder Main-II relay is static type, bus as per CEA (Technical Standards for Connectivity to Grid) Regulations, 00 under Part-III, Section-, both Main-I and Main-II distance relays are to be of numerical type. Main-I & Main-II Numerical relays provided on 0kV Arasur feeder are of same make and model. 0kV Ingur SS 0..0 Time synchronization facility for global common timer reference is not available at the substation which is given in CEA (Measures relating to Safety and Electric Supply) Regulations, 00 under section, clause -(viii). On 0 kv MTPS feeder Main-II relay is static type, bus as per CEA (Technical Standards for Connectivity to Grid) Regulations, 00 under Part-III, Section-, both Main-I and Main-II distance relays are to be of numerical type. Main-I & Main-II Numerical relays provided on 0kV Arasur and K.R.Thoppur feeders are of same make and model. In Busbar Protection same CT is used for Main & Check zone relay. 0kV North Chennai TPS SS(Gen) 9, Current Transformer were tested for Tan Delta during the commissioning only. No periodic tests and maintenance carried out till date. The dates of commissioning of individual Ct s is listed. CTD protection are not provided in all 0KV feeders and Transformers. Earthing pits are not maintained since commissioning. Earth mat resistance and individual earth pit resistance are not regularly observed. Adequate fire extinguishers are not provided as specified on the name plate. Observations was made that the relay setting as decided by local competent authorities. Mid point of station battery should be connected to earth leakage relay. But it is observed that the charger voltage values are monitored instead battery voltage. nd source of D.C supply is availed from Generating station batteries. Observation are made that same type and make relays are provided in some of the feeders. Remote temperature indicators may be provided for station transformers. As per the data available regarding nd source of D.C supply it is not reliable to depend on this supply. It was also discussed with Generation wing and found that the nd source of supply 9 cannot be relied on Gen station battery. Hence it is suggested for a new battery system as nd source of supply for the switch yard.

7 9 &0 00kV Almatty SS(IS) & 0kV Almatty SS 0..0 Protection Relays on 00 kv & 0 kv side are not synchronised with GPS. Main I & Main II Relays found to be of same type & make for some 0 kv #s. In the 00 kv & 0 kv yard the following observations were made. i) Earth mat was designed and installed at the time of commissioning only. There is no provision to measure earth resistances. The Neutral of each ICT have individual earth pit but there is no provision to measure earth resistance and the earth pits are not maintained at regular periods. ii) The Mulsifire Systems are found to be not installed properly. Also since installation, no maintenance has been carried out. Earth leakage Relays are not in service. 0kV Tiruvalam SS(IS) 0..0 Lightning Arresters are not provided on all 0 and 0KV feeders. Battery earth leakage meters provided for DC source I & II are not working. Non Directional Over Current relay with 0% on both sides of all Auto Transformers are provided. Earth fault relay on both side are not adopted. 00kV BTPS SS 0..0 High setting for the bus bar differential protection i.e. V. A/R Selection switch is kept in non auto mode for all 00 kv lines. Dead 0 V DC Earth fault for both sets i.e. Positive to Earth V. Periodic checking of the 0V DC and V DC batteries should be adopted. GPS time synchronisation for all the relays & DR not carried. Pole descripency relay setting kept at 0. Sec for all the lines. Periodic checking of all the switch yard equipment needs to be carried.. Switch yard deweeding needs to be carried. 0kV BTPS(IS) kv Bus coupler not commissioned. Dead Earth fault in 0 V DC set &. relays not Synchronised with GPS. A/R Scheme for 0 kv Lines not available for lines. 0kV Alipur(IS) 0..0 All 0 kv line and bus coupler C&R panels distance relays are retrofitted with ABB REL relays & REL0 respctively, but the existing panels back-up electromechanical relays are very old and sluggish, most of the TS relays are not working properly, announciation not working hence it is suggested to replace the panels at the earliest. Diesel set battery need to be replaced. Bus coupler breaker is out of service due to compressor problem, needs immediate rectification. Carrier aided protection scheme has only single channel for 0 kv BTPS feeder and for 0 kv Ragulapadu line is out of service. Telecome panel need to be replaced. For both transformer protection relay setting adopted differs with the recommended setting same should be reviewed and adopted. No PL carrier voice communication available. For Ragulapadu line carrier inter tripping should be restored. For 00MVA-I No REF protection available and over flux relay should be restored. 9 Bus coupler relay setting for lines differ with recommended setting same to be reviewed and adopted. 0 Battery set 0V-SET I and V both set are of more than years needs capacity check and curative discharge. For putting battery set in to Float/boost proper system should be adopted, during audit it was observed that battery set-i had sp gravity more than 0 but still kept in boost charging.

8 0kV Gajwel SS 0,..0 Carrier aided protection scheme implementation to be examined. PC Test reports of CT's and CVT's shall be mailed by APTRANSCO. It is observed that all 0 kv lines relay panel contains same make relays for Main &. It may be examined for utilising two different make numerical relays. It is observed that 0 kv KAMAREDDY line distance relay settings are not matching with recommended settings of some function. It is observed that 00MVA PTR-I, O/L Relay settings of HV and LV side are mismatching. Periodical relays testing records of 00 MVA, PTR-II & 0 kv MEDCHEL-II not available. Periodical Tan-Delta and Capacitance measurement tests of CT's are not done. Replacement of Static type ABB make Differencial relays (RADSB) provided in, PTR-& by numerical relays may be examined. 00MVA PTR- OLTC tap position indicator in RTCC panel is faulty. 00kV Gajwel SS 0, kv Ramagundam line PLCC Panels are very old and replacement of PLCC Panels to be examined. PC Test reports of CT's and CVT's shall be mailed by APTRANSCO. MVA ICT- O/L realy setting of HV & LV adopted is not matching with the recommended setting. Recommended setting of Main- & Main- is not available for verification. Hence adopted setting to be verified with recommended setting. Adopted setting of Main- relay is not verified due to the non availabilty of relay software. MVA ICT- OLTC tap position indicator in RTCC panel is faulty. Periodical relay testing records of MVA, ICT-II not available. Periodical Tan-Delta and Capacitance measurement tests of CT's are not done due to non availability of testing equipment. Replacement of Static type ABB make Differencial relays (RADSB) provided in ICT-& by numerical relays may be examined. Downloaded copies of DR are to be maintained. 0kV Yeddumailaram SS 0..0 MAX. DC Earth leakage observed in the 0V DC system, to be rectified. Precommissioning test reports of CT & CVT are not available to record the percentage ratio error & ratio measured. Implementation of carrier aided protection scheme may be examined. providing second DC sources for all the control and relay panels may be examined for better reliability. 0 kv Bus bar protection relay along with in-built LBB function is kept out of service. It is observed that 00MVA PTR-I Relay panel contains DTH- static relay and 00MVA PTR-III contains RADSB static relay for differential protection. 0 kv Shamshabad line Main- I distance realy is having static relay of ABB (RAZOA). Replacement of above mentioned static relays by numerical relays may be examined. settings of HV and LV side are mismatching. It is observed that 0MVA PTR-II, HV over flux is provided and LV side over flux is not provided. 00 MVA, PTR-III Earth fault relay Time setting for HV and LV side to be verified as adopted setting is not matching with the recommended settings. 0MVA, PTR-II HV O/L and E/F realys are faulty and also LV side E/F relay to be checked. So replacement of faulty realys to be made. 00 MVA, PTR-III recommended settins of O/F realy not provided for verification. 0 kv Gachibowli line Main-II distance relay is found deffective. 9 Adopted Zone-III setting in Shadnagar Main-I Distance protection is not matching with the recommended settings. 0 Adopted Zone-III Timing setting in Shamshabad-II Distance realy is not matching with the revised recommended settings. Metal sprading is not found in 0 kv S/S yard & kv yard. Cable Trench is not provided in 0 kv Gachibowli, 00MVA PTR-II and B/C.

9 0kV Shivarampalli SS DC earth leakage observed in the 0KV DC-I system, to be rectified. Precommissioning test reports of CT & CVT are not available to record the percentage ratio error & ratio measurement. Implementation of carrier aided protection scheme may be examined. Utilising the two DC sources available for all the control and relay panels may be examined. 9 0kV Gachibowli SS 0 00kV Mysore SS 00kV UPCL SS It is observed 0 KV mamidipally & Gachibowli lines realy panel contains same make relays for Main &. It may examined for utilising two different make numerical relays. It is observed that 00 MVA PTR-I relay panel contains static relay for differential protection. 0 KV HIAL & Gachibowli-I are having ABB (RAZOA)make static relays for Main-II distance protection. Repalcement of above mentioned static relays by numerical relays may be examined. It is observed that 00MVA PTR-I, LV over flux is removed. To be provided. 00MVA PTR-III Existing LV directional earth fault relay is faulty, hence relay may be replaced. 00MVA PTR-III HV directional earth fault relay is not responding, the relay may be tested and replaced if necessary. Provision is not available for LV over flux protection in 00 MVA, PTR-II. Distance relay calculation details shall be provided. Over flux relay is to be provided on HV side of 0/ kv, 00MVA PTR-. DC earth leakage observed in the 0KV DC system-i&ii, to be rectified. Carrier aided protection scheme has to be implemented. Precommissioning test reports of CT & CVT are not available to record the percentage ratio error & ratio measured. Utilising the two DC sources available for all the control and relay panels may be examined. Replacement of existing Main-II Static distance scheme in feeders, Differencial relay DTH provided in 00 MVA PTR-may be examined. Replacement of static relays (THR, CAG, RADHA etc.) with numerical relays may be looked into. Co-ordination of protection settings for 0 kv Downstream lines may be done to avoid un wanted trippings at Mysore SS. Station is generally found to be in order It is observed that 00 kv BuS voltage is on the higher side since from the commissioning of 00 kv Hassan-Udipi line,. Action needs to be taken to reduce the stress on the equipment. The extension of permissive trip to Hassa SS in the event of O/V trip also at Udipi end needs to be verified & rectified at Udipi end. Based on the revised line parameters received from KPTCL, new settings adopted in Main- & relays during October 0.

10 00kV Hassan SS It is observed that 00 kv BuS voltage is generally on higher side. This problem has further aggravated with commissioning of Hassan-Udipi, lines. (As seen from the data available for 0 & th of October 0 approx, 0% of the time voltage is more than 0 kv.) It is observed that permissive trip is being received at HassanSSintheevnt of any trip in line protection relays at Udipi end, which is unwarrented. It needs to be verified at Udipi end. POWERGRID has already informed the issue to RT/KPTCL/HSN for necessary followup/correction. Based on the revised line parameters received from KPTCL, new settings adopted in Main- & relays. It is already under review at POWERGRID/RHQ. Early action may be taken to adopt the revised relay settings. 00kV Somanahalli SS(IS) Nomenclature of Binary Inputs/Binary Outputs & function is to be made in DR. 0kV Somanahalli SS kV Ennore TPS SS(Gen) 0..0 The highest element setting of HV side DOCR & DEFR of each 00 MVA Transformer in Amps. The same is to be reviewed taking 00 kv Bus fault level into consideration. CT/PT Ratio Error is not being done periodically. Synchronizing facility available, is not usede. Condition monitoring of switch yard equipments need to be carried out at regular basis. Synchonising is being used selectively. Recommended for usage at all Lines. Facility for downloading of disturbance records is to be made available. VT fuse fail indication available in Main-I relay of Tondiarpet and Manali feeders. Synchronisation relay not available for feeders. Being done manually by watching indicating meters Earth fault relay not provided on HV & LV sides of Auto t/p #, and TO # t/f. Over fluxing relay also not provided. OT and WT indicators suspected for not working. May be checked. PRV device not available on Auto T/f # and. Since switchyard is very old, it is advisable to physically see the rusting status of earth mat. Switchyard equipment earthing needs to be improved. No LA is available on R-phase LV side of Auto # Surge counters not available on lightening arrestor. Negative terminal of both 0 D/C system found earthed. May be removed. 0V DC 9 system to be maintained isolated from earth. 0 0 msec discrepancy in Z T Main-I & Main-II relays may also be looked into. Dedicated feeder PT/CVT not available for feeders protection. However, single phase CVT available for measurement and synchronisation purpose.

11 0kV Todiyarpet SS kv transmission line earth is generally to be connected to gantry shield wire and further to substation (SS) earth mat. Transmission line earth wire not connected to SS earth mat at Tondiarpet. This may be looked into in perspective of relay accuracy. Provision of LAs at line entry for 0 kv feeders may be considered. 00 MVA, 0/0 kv transformer #&,backupo/crelaysareset at 0% of full load current on boty HV and LV sides. This may be examined. Providing E/f relays on both HV & LV sides may be explored. REF for transformer #, overfluxing relays for both t/f #, not available. May be explored. Earthing of equipment needs improvement. Measurement of earth resistance to be carried out. Synchronous relay not available. Being done manually. Positive terminal of 0 V DC system observed to be earthed. May be rectified. Availing tertiary connection may be explored for auxiliary supply of station. 9 Separate treated earthpit for DG set may be provided. Body of DG Set to be earthed with suitable flat or conductor. 0kV Manali SS 0..0 The condition of 0 kv & 0 kv switchyard is observed to be execessively deteriorating. May faults were attributable to conductor leads/jumpers cut or damage and non operation of circuit breakers. Heavy rusting on equipment and its earth flats is observed. It is felt that this fast deterioration may be due to prevailing environment conditions. To maintain the reliability of this substation, suitable alternatives may be explored to obviate the fast deterioration in future. O/C and E/f relays on HV & LV sides of both auto transformers is set at 0% of full load current. The setting may be revised to suit full load current. Providing LAs at entry and connecting TL earthwire to SS mat may be looked into. Practice of adopting same make and same type relays for both Main-I & II of a 0 kv feeder may be discouraged. Positive terminal of both the 0 V DC systems earthed. May be rectified. Earth resistance meaured on It is observed to be violating in more number of earth pits. The same may be rectified on top priority. 0kV Peenya SS V Battery set # (Exide) commissioned during 9 still in working condition. In Hebbal feeder CVT is provided in "R" ph only. The same may be provided in one more phase. Bus bar protection was not available, same may be provided. GPS, Disturbance recorder and event logger are not available and same may be provided. Control panel annunciation not in working condition except transformers Main-II Distance protections were not propvided in all 0 kv feeders and PLCC/Protection coupler was not provided except 0 kv Hebbal feeder DC negative to earth is persisting and same to be attended early. The support structure and equipments to be replaced. The above works may be taken up on priority basis under the renovation and modernisation which h has already been approved.

12 9 & 0 00kV Nelamangala SS(IS) & 0kV Nelamangala SS Main II distance protection were not provided in all 0 kv lines and PLCC/Protection Coupler were not provided except Nittur & Dabuspet lines Separate Event Loggers are not available, GPS are not synchronised with SAS & Distance Protection Relays. Main II relays not in service in 00 kv Hassan line, 00 kv Talaguppa line & 00 kv Hoody line- and the same may be made available in the above feeders. It is noticed that the LA is failed in the same phase (Talaguppa line) for times previously. Analysis may be done and take remedial action to avoid reoccurrence. 0kV NRS SS.0.0 Event logger and DRS not available for Peenya & Vrushabavathi Lines. Annunciation panel for Peenya line & Vrushabhavathy line are not in working condition. The same may be made available. Winding / Oil temperature Indicator are not in working condition. The same may be made in working condition. Capacity of the DG is insufficient for the Station Aux Supply. Main II Distance protection Relays for all 0 Kv feeders is not available & the Protection Coupler for Peenya & Vrushabavathi Lines are not available. 0kV Spectrum SS(Gen)..0 It is observed that there is no O/V protection, df/dt & UFR protection for both the 0 kv feeders. PLCC inter trip protection is not in service for both feeders. GPS is not available. 00kV Vemagiri SS 0..0 Observed that there are no under frequency and df/dt protections. 0kV GMR Bordge SS(Gen)..0 For 0 kv line # protection relay recommended settings to be adopted. In 0 kv line #, main # & protection relay following deviations observed: a) Distance protection Zone: time of operating t pp adopted:. sec; Recommended 09.sec b) Power swing detection I base current adopted: 000 A; Recommended: 00 A c) Time delayed phase overcurrent protection () Adopted: ON; Recommended: OFF d) Time delayed phase overcurrent protection () Adopted: ON; Recommended: OFF e) Time delayed over voltage protection () Adopted: ON; Recommended: OFF f) Synchro check (9) Adopted: ON; Recommended: OFF For 0kV Line # Distance protection Zone: time of operating t pp Adopted:. sec; Recommended : 0.9 sec 00kV Gauthami SS 9..0 Auto reclose scheme is kept in OFF position for both 00 kv feeders. Over voltage stage- time setting of line- is deviating from recommended setting i.e. recommended setting is sec & adopted setting is sec. It is observed that there is no under frequency and df/dt protections for both 00 kv feeders. 0kV Reliance SS(Gen) 9..0 Recommended relay settings are not available with the utility Main-I protection zone settings are deviating with recommended settings as per record of M/s. Reliance. PLCC Inter Tripping Scheme was not in service. O/V, U/F & df/dt protections are not available for both the feeders. M/s. Reliance request APTRANSCO to communicate for any modifications required in relay settings 00kV Konaseema SS 0..0 Over current relay High. Set value of STGT is 9. instead of. Over voltage stage- time delay setting is sec instead of sec in 00 kv Line #. Observed Auto reclose selection is in non auto mode for both the 00 kv feeders Observed there is no U/F & df/dt functions for both the 00 kv feeders

13 & 9 00kV Jegurupadu SS & 0kV Jegurupadu Ss(Gen)..0 Auto reclosing scheme is in off condition for both Line- and Line-. O/V Stage- protection setting is observed at % (V) instead of recommended 0% (0V) 0 & 00kV Pondichery SS(IS) & 0kV Pondichery SS(IS) 9 & Switchyard, DG Set yard, Battery Room, Bay control KIOSKS, Control Room are maintained neatly. Most of the records & commissioning reports are available & furnished. Substation declared & operated as unmanned (Remote operation from Sriperumbudur SS) w.e.f The station name in test report of ICT & are wrongly mentioned as Sriperumbudur Botyh LBB & BB Protection are in-built in the same Siemens SIPROTEC Relay for both Main & Time Settings in 0 kv VLNR & BHR noted in the relay are as follows: a) Zone : 00 ms b) Zone : 00 ms The Zone & Zone timing of the 0kV feeders as per PGCIL CC Engg are 00ms & 00ms respectively and the actual settings adapted as 00ms & 00ms may be reviewed 0kV Nagjheri SS(Gen)..0 0kV Kadra SS(Gen) 0..0 & 00kV Talguppa SS & 0kV Talaguppa SS..0 0 kv Nagjhari-Ambewadi & lines does not have CVTs on the line. Carrier tripping was not available for these lines. Remaining six 0 kv lines have only one R-Phase CVT and Y & B Phase CVTs are not available. Synchronising of 0 kv feeders is not being done with synchroscope, only Generator Transformer Units are being synchronised. The Neutrals of generator transformers are not earthed exclusively and all LAs also not found to be earthed exclusively. The Emulsifier system nozzles are not directed towards Power Transformer body in the middle. The LBB relay time & current are sdet at. sec & 0. A for all feeders and generating transformers. Carrier protection is out of service for Karwar & feeders Main- Distance protection (SHPM0) is not in service due to power supply module problem for Karwar & feeders Karwar & fereders have only R Ph CVT available (Y and B Ph CVTs are not available). For Kaiga and Kodasalli feeders have only R & B CVTs available. (Y Ph CVT not available) Double earthing of all the supporting structures/elements is to be ensured. Neutrals of generating transformers and LAs are to be exclusively earthed. Bus coupler and transfer bus are out of service, bus coupler module on busbar protection panel is kept out of service. Synchronising of 0 kv feeders is not being done with synchroscope (Synchroscope available) but generator transformer units are being synchronised. CTs should be tested for capacitance and Tan-delta periodically to monitor the insulation healthiness at least once in a year. All isolators and breakers should be tested for contact resistance measurement periodically. All breakers should be tested for Trip/Close timings periodically. LA monitoring reading (leakage current) may be recorded periodically to monitor the healthiness of LAs.

14 0kV Sharavathi SS(Gen) 0..0 Instrument Transformers Only cores are present on certain 0 kv feeders and generator transformers CTs, limiting the Bus Bar protection to only Main zone without check zone. Only one CVT is present on all 0 kv feeders, limiting the line protection Main and Main-II to be only on Bus PT Recommendations corectsmaybereplacedwithcrorectstokeepthebusbarprotectioninfullshape with both Main and Check Zone. CVTs may be provided on all 0 kv feeders so as to keep the Main-II protections on Bus PT or CVT which increases the reliability of the protection system. Bus bar Relay Bus bar protection scheme not having check zone feature due to lack of check zone relay and lack of cores in CTs of certain feeders. Bus bar scheme is very old (Electro mechanical Type-9) and obsolete. Recommendations Bus bar protection panels may be replaced with new panels of numerical relay type to have the bus bar protection in full shape with all features (check zone, CT fail, iso fail etc. features) as the existing scheme is not having check zone facility. Certain CTs with cores should also be changed to have cores for bus bar protection. LBB relay timing is observed to be 0. sec which is high, can be reduced to 0 to 00 m.sec in coordination with pole discrepancy relay of breaker. Transmission line protection Certain 0 kv feeders (S, S, S and ST) are having both Main- & Main- protection on the same core. Certain 0 kv feeders (SS, SS) are having same Make & Type (ABB-REL ) relays as Main-I and Main-II protections Certain 0 kv feeders (S, S, S, S, ST, ST, SB) are having O/C and E/F relays as Main-II protection. Certain 0 kv feeders (SS, SS) are not having carrier protection. Recommendations Feeders having same core for Main-I and Main-II should be separated to individual cores, i.e. Main-I and Main-II should be on different CT cores. Feeders with same Make & Type relay as Main-I & Main-II should be changed with different Make/Type relays for Main-I & Main-II. Feeders having O/C and E/F relays as Main-II may be replaced with distance relays for good protection coordination on 0 kv Grid. Carrier protection should be kept in service for the feeders having no carrier protection. DC supply ThereaeNosbattery banks (00 AH, 000 AH) of lead acid type, for which there is no practice of subjecting the batteries onto periodical load discharge test and recording the battery performance on load condition. The battery bank-i is of led acid type and are observed under poor condition leading to individual cell average cell voltages of. V with average specific gravity 90, which is far below the healthy values. The battery back-ii is also of lead acid type and observed under complete deterioration condition with total bank open circuit voltage V which is far below the 0 V. DC earth leakage oserved on DC-I system with +ve to ground 0 V and -ve to ground. V. Recommendations Battery bank-i should be properly maintained subjecting the batteries to regular periodical load discharge test on every month/fortnight and duly recording the individual cell parameters for future reference/observance. The battery bank-ii may be replaced with VRLA (maintenance free) type batteries to increase the reliability of DC system, as the existing both banks are of lead acid type are under complete deterioration condition. DC earth leakage should be arrested on top priority to avoid spurious trippings due to DC earth leakage. Breakers Nos. 0 kv breakers are of bulk oil type breakers (BOCB, 9 made) which are on Bus Sectionalizer-I & II, which are very old and are observed in poor condition, served beyond its life. The breakers are having inbuilt CTs, used for bus bar protection which on failure is very difficult to replace of its type. Recommendations New SF type circuit breakers may be replaced without door type CTs on either side of the breaker in place of existing old BOCBs, as the sectionaliser breakers are very vital while clearing the very high level bus faults. Earthmat resistance There is no practice of measuring earthmat resistance periodically and recoording the values. Recommendations Earthmat resistance (combined earthmat resistance and individual earth pit) should be measured and recorded periodically. General remarks CTs, transformers may be tested for capacitance and Tan-delta periodically to monitor the insulation healthiness. All protective relays should be tested periodically (once in a year) without fail. Substation GPs may be connected to event logger and protection relays for correct recording of the sequence of events. All generator transformers OTI & WT shall be brought to control room for better monitoring of the transformer performance. PLCC counter upon every tripping may be recorded. LA monitoring reading may be recorded periodically to monitor the healthiness of LAs.

15 0kV Mylapore SS 0..0 For 0 kv Basin Bridge Feeder Protection Main I No carrier scheme is available No protection during VT Fail condition Main II Numerical relay may be provided Auto Transformers I & II No E/L protection on HV & LV side LAs may be provided for desired protection of Auto Transformers DC System Neither +ve or -ve have high resistance grounding Earth leakage monitoring system is required For V (SCADA/PLCC) only set of Battery and Charger, No back up is available. Earthing System No record/log is available for periodic earth resistance measurement No separate earthing for DC system No separate earthing for V DC system General All the CTs, PTs, CBs are tested during the commissioning only, no periodical tests were crried out. No commissioning test results are certified by competent authority Only Bus PT supply is available for Main I & II protection, no line VT supply is available for protection. No Capacitor Tripping Devices are kept in service for Feeders and Transformers. It is learnt that relay settings for feeders and transformers are calculated as per TANTRANSCO. DG set of 0 KVA was commissioned recently, no full load test was carried out. Evidence for recommended/approved settings were not furnished during audit.' Low voltage profile were observed. 9 It is suggested to provide GPS for synchronisation for better disturbance analysis purpose. 0 Inbuilt DRs in the relays are configured, no separate DRs & EL found. To maintain the adequate temperature for GIS equipments air conditioned may be required.

16 Name of Substation 0kV Basin Bridge SS Date of Audit..0 Observations/Remarks For 0 kv Mylapore Feeder Protection No carrier scheme is available No protection during VT Fail condition For 0 kv Tondiar Feeder Protection No protection during VT Fail condition Auto Transformers I, II, III No E/L protection on HV & LV side O/L settings may be reviewed DC System For V (PLCC) only set of Battery, No back up is available. Earthing System No record/log is available for periodic earth resistance measurement No separate earthing for DC system (0 V DC) General All the CTs, PTs and Auto Transformers are tested during commissioning only, no periodical tests were carried out to know the deterioration. No commissioning test results are certified by competent authority Only Bus PT supply is available for Main I & II protection, no line VT supply is available for protection. No Capacitor Tripping Devices are kept in service for Feeders and Transformers. 9 0kV Hitech SS(Gen)..0 It is learnt that relay settings for feeders and transformers are calculated as per TANTRANSCO stipulated standards. It is suggested that it may be calculated by considering system fault levels and time gradation in addition to other parameters as per manual. DG set is required for alternate source. Evidence for recommended/approved settings were not furnished during audit.' Low voltage profile were observed. 9 It is suggested to keep GPS in service at the earliest for better fault analysis. 0 Auto reclosure is not enabled for feeders. Power swing block settings may be reviewed. Evidences for recommed/approval relay settings are not available. Earthing system may be improved. There is no standby battery bank and charger. Periodical testing of switchgear shall be carrie out. Real time data transfer facility to SLDC shall be established. Dedicated hot line speech facility to SLDC shall be established.

17 90 0kV Koratur SS..0 Protection During VT fail condition no protection is available (Backup > disabled) No E/L relay protection on ATR, & HVs V/F protection is not available on ATR-, & It is observed that Main- & schemes of feeders are of same make General Only Bus PT supply is available for Main I & II protection. There is no line VT supply available for protection. Only Bus PT supply is available for Main- & protection. There is no Line VT supply available for protection. No capacitor tripping devices are provided on 0 kv feeders & ATRs. 9 0kV Naganathpura SS 9 0kV HSR Layout SS 9 0kV Lingapur SS It is learnt that the relay settings for feeders and transformers are calculated as per TANTRANSCO stipulated standards. It is suggested that it may be calculated by considering system fault levels and time gradation in addition to other parameters as per Relay manual. Evidence for recommended/approved settings were not furnished during audit. GPS may be established for effective fault analysis. In Bus bar protection relay Master Card is faulty, sent for repair to M/s. ERL. Main-: Numerical Distance Protection and Main- is Back up protection with OCR & EFR. Main- protection is Distance Relay and Main- protection is Back up relays with OCR & EFR. Bus Bar protection relay is out of service, the same may be put back to service for protection. DC Charger-I, the earth reference point may be rectified/checked. On for the 0 kv Hoody Line fault, the transformer- HV & LV tripped. The relay setting may be reviewed. CVTs should be there for all the feeders for protection. LAs are not available for all feeders except Jindal & Surge monitor needs to be provided for Jindal Only one core of CTs is used for both main and B/U relays for all feeders except Jindal & Bus bar protection not available GPS clock is not available PTs are to be commissioned on reserve bus Synchronisation relay is not working For all feeders O/C and E/F relay as B/U protection can be replaced with distance 9 scheme mostly numerical relay is recommended. 0 Approved relay settings are not available for all B/U relays. Only single carrier channel is available for carrier protection and all the feeders does not have carrier protection except BTPS, Sindanoor, Gudadahalli - &andharthi. New CTs and CVTs available at yard needs to be commissioned at the earliest.

18 9 0kV A'Station 0..0 Busbar protection is to be commissioned One DC source is being user for protection. Main-II protection is not available. However, electromechanical type backup protection relays have been provided. 9 0kV Hebbal SS 0..0 One DC source is being user for protection. Main-II protection is not available. However, electromechanical relay used as back up protection. LBB relays not available. DG set is not available. 9 0kV Yerandahalli SS(IS)..0 For Main-II distance relays preferably numerical relays are not available in all 0 kv feeders, the same to be provided. Busbar protection is not provided in the 0 kv system, the same to be provided. 9& 9 00kV Tuticorin SS &0kV Tuticorin TPS SS(Gen)..0 Nil 99 0kV Kayathar SS..0 Earth resistance to be measured and recorded. Grass growth to be controlled in the switchyard area. Cable routing to be done properly. Renovation of control room to be done. Proper fire fighting and oil drain pit to be provided for transformers. 00 0kv Arani SS..0 Static Version relays are to be replaced with latest version numerical relays for quick and accurate analysis of faults. V/F protection is not enabled in TNEB upto the level of 0 kv. REF protection is not implemented in TNEB for Transformer Capacity below 00 MVA. Lightning Arrestors are not provided for 0 kv feededrs. Second source of DC may be reviewed for connectivity. DG set is under faulty and enhancement proposed. DC leakages are to be attended for source I. No written documents for approved relay settings. 9 Syn check relay is not available. 0 0kv Aliyar SS(Gen) 9..0 Nil 0 0kV Theni SS(IS)..0 Nil 0 0kV Kadamparai SS(Gen) 0..0 Nil 0 0kV Raichur SS(Gen) V DC earth fault persisting negative dead grounded Old electromagnetic relays can be replaced with numerical relays. LBB Relay RAICA RXKL setting for ICT-II is kept at 0 ma. 0 00kV Raichur SS (IS) V DC earth fault persisting with leakage current of ma Daily Battery reading is not taken by putting charger in OFF condition PD settings for Munirabad, BTPS and Mahboobnagar kept at 0. sec Time synchronisation for all the relays, EL and DR are done with GPS RTPS-Munirabad line Zone-II setting (.0 Ohm) is more than Zone-III (. Ohm) No fault locator working for Munirabad and Mehboobnagar lines DR communication is not working for Munirabad and Mehboobnagar lines DG set is not extended to 00 kv SS 9 Old electromagnetic relays can be replaced with numerical relays. 0 0kV Lingsugur SS.0.0 Bus Bar protection is not available in the station, same is to be provided. All 0 kv line and bus coupler C&R panels, distance relays are retrofitted with ABB REL relays & REL0, but the existing panels back up electromechanical relays are very old and sluggish, most of the TS Relays are faulty, annunciation not working, hence it is suggested to replace the panels at the earliest. PLCC Batteries set to be provided. Capacity test and curative discharge needs to be done.