TRIPPPING REPORT PRESENTATION FY 2023-2024

TP Report

1. TRIPPING INDEX FY 2023-2024   UNIT 01 UNIT 02 UNIT 03 UNIT 04 UNIT 05 NO. OF TRIPPINGS 13 15 23 12 12 NO . OF FORCED TRIPPINGS 12 14 22 12 11 NO . OF PLANNED TRIPPINGS 1 1 1 1 TOTAL OUTAGE DAYS 42.1 42.73 18.63 16.58 23.4 MTBF (DAYS) 25 22 15 29 29 MTBF FORCED TRIPPING (DAYS ) 29 26 16 29 31 NO OF BTL 5 1 7 2 9 MTBF BTL (DAYS) 72 365 51 181 38 MTTR BTL (DAYS) 1.54 1.46 1.78 2.14 2.24 NO OF TRIPPINGS ON CARD FAILURE     2   2 MTBF CARD FAILURE     183   183 NO OF TRIPPINGS ON FLAME FAILURE/FURNACE DRAFT 4 3 9 3   MTBF FLAME FAILURE/FURNACE DRAFT 91 122 41 122   NO OF TRIPPINGS ON ELECTRICAL PROBLEMS 1 2   2   MTBF ELECTRICAL PROBLEMS 366 183   182   NO OF TRIPPINGS ON FAN PROBLEMS   4 1     NO OF DAYS   4.596 0.08125     MTBF FAN PROBLEMS   90 366     OTHERS TRIPPINGS 2 4 3 5  

2. SNO UNIT TRIP Date TRIPTime SYNCH Date SYNCH Time HOUR GEN LOSS NATURE REASON REMARKS HOUR_DET 1 UNIT01 4/15/2023 06:30:00 4/17/2023 06:39:00 48.09 10.111500 FORCED AIR HEATERS PROBLEM   48:09 2 6/24/2023 22:47:00 6/26/2023 21:00:00 46.13 9.705500 FORCED BTL - REHEATER   46:13 3 6/27/2023 04:06:00 6/27/2023 12:44:00 8.38 1.813000 FORCED ELECTRICAL PROBLEM - SWITCHGEAR PROBLEM   8:38 4 6/30/2023 00:18:00 7/29/2023 13:13:00 708.55 148.872500 PLANNED ANNUAL OVERHAUL   708:55 5 7/29/2023 13:24:00 7/30/2023 19:18:00 29.54 6.279000 FORCED TURBINE BEARINGS VIBRATIONS HIGH   29:54 6 8/4/2023 05:36:00 8/4/2023 14:17:00 8.41 1.823500 FORCED FURNACE PRESSURE VERY HIGH   8:41 7 8/26/2023 01:40:00 8/27/2023 20:22:00 42.42 8.967000 FORCED BTL - REHEATER   42:42 8 9/4/2023 21:23:00 9/4/2023 23:57:00 2.34 0.539000 FORCED FURNACE PRESSURE VERY HIGH   2:34 9 9/14/2023 01:30:00 9/14/2023 03:33:00 2.03 0.430500 FORCED FURNACE PRESSURE VERY HIGH   2:03 10 10/30/2023 11:39:00 10/30/2023 20:04:00 8.25 1.767500 FORCED FURNACE DRAFT Excitation System Problem Occured. 8:25 11 11/26/2023 00:42:00 11/26/2023 09:52:00 9.1 1.925000 FORCED DRUM LEVEL VERY LOW   9:10 12 12/5/2023 16:43:00 12/7/2023 14:18:00 38.18 8.043000 FORCED BTL - PRIMARY SH / FINAL SH / PENDANT SH   38:18           7.17 1.529500 FORCED BTL - REHEATER   7:17 13 1/14/2024 06:04:00 1/16/2024 07:50:00 49.46 10.451000 FORCED BTL - WATER WALL ZONE   49:46 1 UNIT02 4/2/2023 07:49:00 4/3/2023 18:52:00 35.03 7.360500 FORCED BOILER TUBE LEAKAGE - WATER WALL ZONE - LONG TERM OVER HEATING   35:03 2 4/12/2023 15:07:00 4/12/2023 18:30:00 3.23 0.710500 FORCED ID FAN BEARING TEMP HIGH   3:23 3 4/13/2023 21:34:00 4/14/2023 02:35:00 5.01 1.053500 FORCED ELECTRICAL PROBLEM - SWITCHGEAR PROBLEM   5:01 4 5/4/2023 18:55:00 5/4/2023 22:25:00 3.3 0.735000 FORCED DRUM LEVEL VERY LOW   3:30 5 5/19/2023 21:48:00 5/20/2023 00:49:00 3.01 0.633500 FORCED FLAME FAILURE   3:01 6 5/28/2023 01:18:00 5/28/2023 11:23:00 10.05 2.117500 FORCED SWITCHGEAR - LT BREAKER PROBLEM   10:05 7 6/29/2023 04:43:00 6/29/2023 08:15:00 3.32 0.742000 FORCED DRUM LEVEL VERY LOW   3:32 8 7/3/2023 23:29:00 7/4/2023 09:40:00 10.11 2.138500 FORCED ID FAN PROBLEM   10:11 9 7/27/2023 13:57:00 7/27/2023 16:21:00 2.24 0.504000 FORCED FURNACE PRESSURE VERY HIGH   2:24 10 9/10/2023 10:00:00 9/11/2023 15:28:00 29.28 6.188000 FORCED CHP BUNKERING PROBLEMS   29:28 11 9/12/2023 00:10:00 9/12/2023 04:41:00 4.31 0.948500 FORCED COAL MILL NOT AVAILABLE DUE TO MILL CHOKE-UP   4:31 12 9/13/2023 20:11:00 9/14/2023 00:31:00 4.2 0.910000 FORCED FLAME FAILURE   4:20 13 10/17/2023 04:44:00 10/18/2023 02:24:00 21.4 4.550000 FORCED FD FAN PROBLEM   21:40 14 11/17/2023 10:28:00 11/20/2023 13:33:00 75.05 15.767500 FORCED ID FAN PROBLEM   75:05 15 1/10/2024 23:30:00 2/13/2024 21:44:00 814.14 170.989000 PLANNED ANNUAL OVERHAUL   814:14 4x210 MW Tripping Report For FY -2023-24

3. 4x210 MW Tripping Report For FY -2023-24 SNO UNIT TRIP Date TRIPTime SYNCH Date SYNCH Time HOUR GEN LOSS NATURE REASON REMARKS HOUR_DET 1 UNIT03 4/12/2023 10:20:00 4/13/2023 15:00:00 28.4 6.020000 FORCED BTL - ECONOMISER ZONE   28:40 2 4/26/2023 11:39:00 4/26/2023 16:29:00 4.5 1.015000 FORCED CARD FAILURE   4:50 3 4/27/2023 13:39:00 4/27/2023 18:56:00 5.17 1.109500 FORCED FIRE HAZARD SET TRIPPED ON MALFUNCTION OF FIRE PROTECTION. 5:17 4 4/28/2023 01:51:00 4/28/2023 08:22:00 6.31 1.368500 FORCED FIRE HAZARD   6:31 5 5/10/2023 08:21:00 5/11/2023 00:24:00 16.03 3.370500 FORCED AIR HEATERS PROBLEM   16:03 6 6/1/2023 07:43:00 6/3/2023 13:19:00 53.36 11.256000 FORCED BTL - LTSH ZONE   53:36 7 6/22/2023 22:48:00 6/24/2023 19:01:00 44.13 9.285500 FORCED BTL - REHEATER   44:13 8 7/6/2023 07:46:00 7/6/2023 10:30:00 2.44 0.574000 FORCED FURNACE PRESSURE VERY HIGH   2:44 9 7/25/2023 15:05:00 7/25/2023 17:25:00 2.2 0.490000 FORCED FURNACE PRESSURE VERY HIGH   2:20 10 8/14/2023 07:33:00 8/14/2023 11:01:00 3.28 0.728000 FORCED FURNACE PRESSURE VERY HIGH   3:28 11 8/19/2023 11:11:00 8/20/2023 17:54:00 29.09 6.121500 FORCED BTL - ECONOMISER ZONE   29:09           1.34 0.329000 FORCED FURNACE PRESSURE VERY HIGH   1:34 12 8/27/2023 06:46:00 8/27/2023 10:14:00 3.28 0.728000 FORCED DCS PROBLEM   3:28 13 9/30/2023 23:55:00 10/4/2023 05:54:00 77.59 16.376500 PLANNED BOILER VALIDITY EXPIRED   77:59 14 10/15/2023 06:20:00 10/15/2023 09:12:00 2.52 0.602000 FORCED FURNACE PRESSURE VERY HIGH   2:52 15 11/1/2023 04:28:00 11/1/2023 08:18:00 3.5 0.805000 FORCED FURNACE PRESSURE VERY HIGH   3:50 16 11/2/2023 03:41:00 11/2/2023 10:42:00 7.01 1.473500 FORCED FURNACE PRESSURE VERY HIGH   7:01 17 11/5/2023 19:08:00 11/5/2023 21:24:00 2.16 0.476000 FORCED DRUM LEVEL VERY LOW   2:16 18 11/14/2023 16:56:00 11/14/2023 18:53:00 1.57 0.409500 FORCED ID FAN PROBLEM   1:57 19 11/17/2023 19:46:00 11/17/2023 22:22:00 2.36 0.546000 FORCED FURNACE PRESSURE VERY HIGH   2:36 20 11/21/2023 12:00:00 11/23/2023 24:00:00 60 12.600000 FORCED BTL - ECONOMISER ZONE   60:00 21 11/29/2023 11:07:00 11/29/2023 13:41:00 2.34 0.539000 FORCED FURNACE PRESSURE VERY HIGH   2:34 22 2/20/2024 23:37:00 2/22/2024 04:14:00 28.37 6.009500 FORCED BTL - ECONOMISER ZONE   28:37 23 2/26/2024 00:48:00 2/28/2024 08:27:00 55.39 11.686500 FORCED BTL - WATER WALL ZONE   55:39 1 UNIT04 5/19/2023 05:57:00 5/20/2023 15:04:00 33.07 6.954500 FORCED BTL - ECONOMISER ZONE   33:07 2 5/26/2023 22:55:00 5/28/2023 04:39:00 29.44 6.244000 FORCED AIR HEATERS PROBLEM   29:44 3 6/5/2023 16:40:00 6/5/2023 18:54:00 2.14 0.469000 FORCED FURNACE DRAFT   2:14 4 9/10/2023 11:37:00 9/11/2023 01:33:00 13.56 2.926000 FORCED FURNACE PRESSURE VERY HIGH   13:56 5 9/20/2023 00:18:00 9/20/2023 08:08:00 7.5 1.645000 FORCED CHP BUNKERING PROBLEMS   7:50 6 10/9/2023 04:58:00 10/9/2023 18:27:00 13.29 2.831500 FORCED AIR HEATERS PROBLEM   13:29 7 10/12/2023 06:58:00 10/12/2023 22:44:00 15.46 3.311000 FORCED EXCITATION SYSTEM PROBLEM   15:46 8 10/12/2023 23:12:00 10/13/2023 01:08:00 1.56 0.406000 FORCED TURBOVISORY PARAMETERS   1:56 9 11/1/2023 10:41:00 11/1/2023 13:00:00 2.19 0.486500 FORCED FURNACE PRESSURE VERY HIGH   2:19 10 11/10/2023 13:48:00 11/16/2023 20:16:00 150.28 31.598000 FORCED AIR HEATERS PROBLEM   150:28 11 12/23/2023 01:00:00 12/25/2023 06:51:00 39.03 8.200500 FORCED PR.PARTS / PIPES / VALVES - TURBINE SIDE CRH PIPE LINE LEAKAGE   39:03           14.48 3.108000 FORCED ELECTRICAL PROBLEM - BATTERY SYSTEM PROBLEM   14:48 12 2/18/2024 14:16:00 2/21/2024 15:26:00 73.1 15.365000 FORCED BTL - LTSH ZONE   73:10

4. UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 2 2/4/2023 7:49 3/4/2023 18:52 35:03:00 7.3605 FORCED BTL-WATER WALL ZONE Set Withdrawn due to BTL in Water Wall Zone.GCB opened on generator reverse power protection. Falling slag erosion is the root cause of failure of water wall front bottom goose neck tube no. 17. Primary Failure: Water wall front bottom goose neck tube no. 17 found punctured. Secondary Failure: Water wall front bottom goose neck tube no. 16 found punctured and tube no. 15 found eroded. Scaffolding erection at Bottom goose neck and in bottom ash hopper carried out. Punctured and eroded tubes of front water wall bottom goose neck replacement carried out. Radiography of all 06 Nos. Of HP weld joints carried out. Fin welding of replaced tubes carried out. Burner tilt system and APH O/L to ESP I/L flue gas duct leakages attended. B-99 & B-100 valve passing & jamming attended. Atomising steam I/L valve at firing floor flange leakage attended . 3 12/4/2023 10:20 13/04/2023 15:00 28:04:00 6.02 FORCED BTL- ECONOMIZER ZONE Set withdrawn due to BTL in Economizer Zone. Localised flue gas erosion is the root cause of failure of tube no. 1, coil no. 1. Primary Failure: Economizer lower coil no. 1, tube no. 1, bend found punctured. 1) Punhemispherical spool pieces. Thickness survey of SCW front & LHS tubes at corner no. 1 in economizer middle zone carried out and thickness observed in normal range. Also, thickness survey carried out at SCW corner no. 1 eco hopper zone found in normal range. Radiography of 02 ctured economizer coil no. 1 plugged in by Nos. Of H.P. weld joint carried out . 4 19/5/2023 5:57 20/5/2023 15:04 33:07:00 6.9545 FORCED BTL- ECONOMIZER ZONE Set withdrawn due to BTL in Economizer Zone. Primary Failure: Economizer upper bank coil no. 39 tube no. 2 found punctured with fish mouth opening. Secondary Failure: 1) Economizer upper bank coil no. 39 tube no. 3 found eroded. 2) Economizer upper bank coil no. 38 tube no. 3 found eroded and tube no. 4 found punctured. 3) Economizer upper coil no. 37 tube no. 3 found punctured . 1) Punctured economizer coil no. 37, 38, & 39 plugged in by hemispherical spool pieces. 2) SS half round protective shield normalization carried out in economizer top zone. 3) Radiography of 06 nos. Of weld joints carried out. Boiler hydraulic test taken at 150 kg/cm2, found ok. Air preheater 4B internal inspection & its gear box servicing & oil seal replacement carried out. SD-3 valve steam leakage attended by dismantling the valve & replacement of spares. Preventive maintenance BFP/vacuum pump /SAF motor carried out. GTR Phase clamp tightness ensure. S/D work carried out. LP bypass opened from local during rolling. BTL

5. BTL UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 1/6/2023 7:43 3/6/2023 13:19 53:36:00 11.256 FORCED BTL- LTSH ZONE Set withdrawn due to BTL in LTSH Zone. Localised flue gas erosion is the root cause of failure of LTSH coil no. 111 tube no. 25. Secondary Failure: LTSH coil no. 111 tube no. 26, 27, 28 observed bent & eroded. LTSH coil no. 112 tube no. 25, 26, 27 & 28 found eroded. LTSH coil no. 113 tube no. 27 & 28 found eroded. LTSH coil no. 108 tube no. 28 eroded. LTSH coil no. 109 tube no. 28 eroded. Eco hanger no. 57 (C) found eroded. Puncture and eroded tubes and bends (90°) of LTSH coil no. 108, 109, 111, 112, 113 & eco hanger 57 (C) replaced by new. LTSH coil no. 111 misaligned stub replacement carried out. Radiography of 31 Nos. Of H. P. joint carried out. 3 22/6/2023 22:48 24/06/2023 19:01 44:13:00 9.2855 FORCED BTL- REHEATER ZONE Set withdrawn due to BTL in Reheater Zone. High temperature creep: The serrations and crack on the surface of the punctured tube of reheater rear coil. no. 30 tube no. 6 leads to the conclusion that high temperature creep is the root cause of failure. creep occurred due to transformation of creep cavities and increased in inside oxide thickness. Secondary Failure: Reheater rear coil no. 30 tube no. 4, 5 & 7 found eroded. Reheater rear coil no. 29 tube no. 5, 6 & 7 found punctured and tube no. 8 eroded. Reheater rear coil no. 28 tube no. 6 found eroded and tube no. 7 punctured. Punctured and eroded tube of reheater rear coil no.28, 29 & 30 replace by new. Radiography of 20 Nos. of H.P. joint carried out. Hydraulic test taken at 150 kg/cm2 , found ok. Reheater vacuume test taken, found ok. 1 24/6/2023 22:47 26/6/2023 21:00 46:13:00 9.7055 FORCED BTL- REHEATER ZONE Set withdrawn due to BTL in Reheater Zone. Attachment weld failure: Cracks developed at attachment weld of the reheater rear coil no. 15 tube no. 5 is the root cause of failure. Secondary Failure: Reheater rear coil no. 15 transition loop tube no. 4 eroded and tube no. 6, 7 & 8 found punctured. Reheater rear coil no. 16 transition loop tube no. 4, 5, 6, 7 & 8 found punctured. Punctured and eroded tube of reheater rear coil no.15 & 16 replace by new. Radiography of 20 Nos. of H.P. joint carried out. Hydraulic test taken at 150 kg/cm2 , found ok. Reheater vaccume test taken, found ok.

6. BTL UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 1 26/8/2023 1:40 27/8/2023 20:22 42:42:00 8.967 FORCED BTL- REHEATER ZONE Set withdrawn due to BTL in Reheater Zone.Welding joint failure: Old welding joint failure of tube no. 6 Reheater rear coil no. 43 is the root cause of failure. Secondary Failure: Reheater rear coil no. 41 tube no. 5 & 6 punctured. Reheater rear coil no. 42 tube no. 4, 5, 6, 7, burst open and tube no. 8, 9, eroded. Reheater rear coil no. 43. Tube no. 4, 5 punctured. Reheater rear coil no. 44 tube no. 6 (bend) eroded. Punctured and eroded tubes of Reheater rear coil no. 41, 42, 43, 44 and 45 replaced by new. Radiography of all 29 Nos. Of H. P weld joints carried out. 3 21/11/2023 12:00 23/11/2023 24:00:00 60:00:00 12.6 FORCED BTL- ECONOMIZER ZONE Set tripped on BTL in Economizer zone. Localised flue gas erosion is root cause of Failure. Routine S/D work carried out. Unit - 3 BTL in economizer upper coil tube attended. Hydraulic test taken, at 150 Kg/cm2, found ok. APH - 3A rotor jamming removed. APH - 3A main drive speed reducer unit gear box servicing done by replacement of bearings. Internal inspection & repair work of both APH carried out. APH O/L to ESP I/L FG duct patching done. Defects as per defect list attended. 1 5/12/2023 16:43 7/12/2023 14:18 45:35:00 9.5725 FORCED BTL -Primary SH/Final SH/ Pendant SH , BTL- Reheater Set tripped on BTL in Platen SH zone. Attachment weld failure is the cause of failure of tube no. 18 of platen SH coil no. 8. Platen super heater coil no. 8 tube no. 21 ( secong inner loop) and tube no. 19 & 20(inner loop) found punctured and eroded. BTL in platen Superheater coil tube attended by replacement of tube Radiography done. Found ok. Boiler Hydrohalic test taken at 150kg/cm2, found ok. APH internal inspection and bearings (support + guide and oil replacement carried out. Defects attended as per defect list. BTL detail report attached herewith.

7. BTL UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 1 14/1/2024 6:04 16/1/2024 7:50 49:46:00 10.451 FORCED BTL- Water Wall ZONE Set tripped on drum level very low with suspected BTL at Water Wall Zone. Thick lip burst with fish mouth opening of water wall corner no. 2, tube no. 3 leads to the conclusion that short term overheating might be the root cause of failure. Secondary Failure: Corner no. 2, tube no. 1, 2 & 4 found eroded. Processor card of HPH group protection. Malfunctioned & got faulty. Hence, FD-10 & FD-11 of feed water line going to HPH were closed suddenly cutting the feed flow to boiler thereby tripping occurred on drum level very low. RH slant portion water washing carried out. Neck scaffolding & sky climber erection carried out. Punctured and eroded tubes of water wall corner no. 2 replaced by new with H.P. welding. Radiography of total 08 Nos. H.P weld joints carried out. Fin welding of replaced tubes carried out. Doghouse repair work carried out. APH-1A and 1B inspection carried out. Axial seal setting done. Since spare processor card is not available, processor card of main group protection of HPH-5 & 6 is not in service. 4 18/2/2024 14:16 21/2/2024 15:26 73:01:00 15.365 FORCED BTL-LTSH ZONE Unit withdrawn due to BTL in LTSH Zone. Localized flue gas erosion is the root cause of failure of LTSH coil no. 98 tube no. 25 Secondary Failure: LTSH coil no. 97 tube no. 25, 26 eroded. LTSH coil no. 98 tube no. 28 punctured. LTSH coil no. 99 tube no. 26, 27 eroded & 28 punctured. LTSH coil no. 100 tube no. 26, 27 & 28 eroded. LTSH coil no. 101 tube no. 28 eroded. LTSH coil no. 93 tube no. 28 eroded. LTSH coil no. 96 tube no. 27, 28 eroded Hanger no. 48 eroded. LTSH coil no. 97, 98 lifted and repair carried out. Punctured and eroded tubes of LTSH coil no. 93, 96, 97, 98, 99, 100, 101 & eco hanger no. 48 replaced carried out. Radiography of 65 Nos of HP joints carried out. Boiler drum RHS side transmitter line valve 40 replaced by new. RHS CRH spray line leakages attended by replacing punctured tube. APH A & B internal inspection carried out. APH 4A, 4B hot end side damage bypass seal replacement carried out. APH 4A, 4B damaged radial seals, bypass seals, static seals, replaced and casing repair carried out. APH 4B gearbox oil seal replaced.

8. BTL UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 20/2/2024 23:37 22/2/2024 4:14 28:37:00 6.0095 FORCED BTL-ECONOMIZER ZONE Unit withdrawn due to BTL in Economizer Zone. Localised flue gas erosion is the root cause of failure. Primary Failure: Economizer upper bank coil no. 149 tube no. 6 found punctured with fish mouth opening. Secondary Failure: Economizer upper bank coil no. 147, 148, tube no. 6, 7 found eroded. Scaffolding erection at economizer hopper carried out. Punctured and eroded economizer coils plugged in by hemispherical spool pieces. (coil no. 147,148 & 149). Shielding normalization economizer top zone. LTSH bottom terminal tube carried out. Radiography all 6 Nos of joints carried out. Internal inspection of APH 3A and 3B carried out. 3 26/2/2024 0:48 28/2/2024 8:27 55:39:00 11.6865 FORCED BTL- STEAM COOLED WALL ZONE Unit withdrawn due to BTL in Steam Cooled Wall Zone. Localized flue gas erosion is the root cause of failure. Primary Failure: Extended steam cooled wall (RHS side), tube no. 2 found burst opened with fish mouth opening. Secondary Failure: Extended steam cooled wall (RHS side), tube no. 1 & 3 eroded. Extended water wall (RHS side), tube no. 1 & 2 eroded. Water wall screen tube no. 61A, 61B punctured & 57B, 60B & 61C eroded. Final super heater coil, tube no. 1 of coil no. 4, 113, 114, 116 & 117 eroded. Punctured and eroded tubes of extended SCW, extended water wall, water wall screen and final super heater coils replaced. Radiography of all 31 Nos. Of joints carried out.

9. CARD FAILURE & DCS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 26/4/2023 11:39 26/04/2023 16:29 4:05 1.015 FORCED CARD FAILURE GCB open on generator reverse power protection. T.G. Set tripped due to processor card fault. At @ 11:39 hrs. DCS control panels CRA04 (CMC), CRA05 (R/H & S/H temp. control) and CJF 22 (SADC) processor cards PR05 failed one by one. Due to this PCR big MW indicator signal got bad. As a precautionary measure operator withdrawal coal mills one by one. But this sudden withdrawal of mill disturbed flame inside boiler and set tripped on flame fail protection. All three panels PR05 cards replaced with home repaired cards. Its parameter setting done and clearance given for light up. 3 27/8/2023 6:46 27/8/2023 10:14 3:28:00 0.728 FORCED DCS PROBLEM Set tripped on DCS Card Failure. Fault appeared on CRA 10 panel BK 3.13 bus. Thereby all hot well and deaerator parameter showed bad and got disturbed. DM 13 & 16 valves (hot well dm make up valves) operated to 100 %. thereby increasing hot well level, both CEPs were also started. Vacuum dropped due to increase in hot well level to –0.7 kg/cm2 thereby tripping the set. Faulty BKO- 2 was replaced by new one. All parameters got normal, DM 13, 16 and condensate cycle normalised . Set was taken on load.

10. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 2 19/5/2023 21:48 20/5/2023 0:49 3:01:00 0.6335 FORCED FLAME FAILURE 21:39 Hrs. ID fan 2A tripped on DE side bearing temperature High w.r.to that FD 2A tripped. Immediately coal cycle 2F tripped. But oil guns are frequently flickering. Suddenly @ 21:45 unit tripped on flame failure 1) ID fan 2A:DE side bearing servicing done. 2) Cone flushing done. 3) Casing patching done. 4) Trail found normal. 5) ID fan put back to service. System normalized as per standard operating procedures and clearance given for light up. 4 5/6/2023 16:40 5/6/2023 18:54 2:14:00 0.469 FORCED FURNACE DRAFT Unit tripped on Furnace Pressure very High due to clinker problem. Due to falling of clinker, flame disturbed inside boiler and furnace pressure varied from –110 to +265 and set tripped on furnace pressure very high protection. System normalized as per standard operating procedures and clearance given for light up. 3 6/7/2023 7:46 6/7/2023 10:30 2:44 0.574 FORCED FURNACE PRESSURE VERY HIGH Set tripped on Furnace Pressure Very High. Due to heavy clinker fall, furnace flame all elevation got no flame one by one and also furnace draft varied and tripped on furnace pressure very high protection. System normalized as per standard operating procedures and clearance given for light up.

11. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 25/7/2023 15:05 25/7/2023 17:25 2:02:00 0.49 FORCED FURNACE PRESSURE VERY HIGH Set tripped on Furnace Pressure Very High. Due to falling of big clinker, flame inside boiler got disturbed. Flame/ no flame indication appeared one by one from top i.e., EF to AB elevation. This disturbed draft inside boiler from –120 to +230 MMWC and set tripped on furnace pressure very high protection. System normalized as per standard operating procedures and clearance given for light up. 2 27/7/2023 13:57 27/7/2023 16:21 2:24:00 0.504 FORCED FURNACE PRESSURE VERY HIGH suddenly furnace pressure varies –90 MMWC to +200 MMWC, Due to falling of clinker, flame and furnace pressure inside boiler got disturbed. And set tripped on furnace pressure very high protection. coal cycle u/p to BM, coal cycle 2B NCF at 13:58 Hrs. Due to soot accumulation in scanner suede pipe, oil gun not proved initially. After cleaning of scanner guns proved one by one. System normalized as per standard operating procedures and clearance given for light up. 1 4/8/2023 5:36 4/8/2023 14:17 8:41:00 1.8235 FORCED FURNACE PRESSURE VERY HIGH set running on 70 MW with four coal mill operation. At 5:33 Hrs. Coal feeder 1B no coal flow occurred same time coal feeder 1A coal flow also flection found. Immediately oil gun taken I/s @ AB elevation. Just before tripping coal mill- B got no coal flow, also 1 D shed load. While taking guns AB1, CD2 proved but this disturbed flame and furnace pressure inside boiler and set tripped on furnace pressure very high protection. System normalized as per standard operating procedures and clearance given for light up.

12. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 14/8/2023 7:33 14/8/2023 11:01 3:28 0.728 FORCED FURNACE PRESSURE VERY HIGH Furnace pressure increased to +400 mmwc at 7:33 AM due to falling clinker thereby causing flickering in scanner & tripping set. System normalized as per standard operating procedures and clearance given for light up. 3 19/8/2023 11:11 20/8/2023 30:43:00 6.4505 FORCED FURNACE PRESSURE VERY HIGH /BTL BTL suspected at economiser zone so while reducing the load set tripped on Furnace pressure very high. Localised flue gas erosion is the root cause of failure of tube no. 1, bend coil no. 161. Secondary Failure: Economizer lower coil no. 160 tube no. 1 bend found eroded. Punctured and eroded economizer coil no. 161 & 162 plugged in by hemispherical spool pieces. Radiography of all 04 Nos. Of joints carried out. EMS screen and Cassette baffle normalization carried out. M5301 valve made operated, Power Fuse replaced. HPBP valve servicing done. APH-3A & 3B internal inspection carried out. APH outlet to ESP inlet duct inspection & repair work carried out. 1 4/9/2023 21:23 4/9/2023 23:57 2:34:00 0.539 FORCED FURNACE PRESSURE VERY HIGH Unit was on 5 coal mills operation. at 21:20 Hrs. coal cycle B withdrawn for removal of clinker formed near reject gate, with oil support at AB elevation. After withdrawal of coal cycle B at around 21:23 hrs heavy clinker formation took place in furnace and the clinker subsequentlly fell resulting in furnace pressure reacting to +454 mmwc . Hence unit tripped on furnace pressure very high. Wide range transmitter showed 454 mmwc and all control trans matters were out of range, but this disturbed flame and furnace pressure inside boiler and set tripped on furnace pressure very high protection. .

13. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 4 10/9/2023 11:37 11/9/2023 1:33 13:56 2.926 FORCED FURNACE PRESSURE VERY HIGH Unit was running on five mill. bunker levels were very low. C/M-4A was not available since long frequent NCF were occurring. C/M-4B, 4C, 4D, run short of coal within 7 min. os (from 11:24 to 11:31) oil support taken in AB 1,2 and all CD elevations. suddenly furnace pressure surged high & unit tripped. System normalized as per standard operating procedures and clearance given for light up. 2 13/9/2023 20:11 14/9/2023 0:31 4:20:00 0.91 FORCED FLAME FAILURE Set tripped on Flame Failure. H-29 (HOTV) suddenly closed due to malfunction of atomising steam pressure low switch malfunction . Atomising control pressure switch made ok. System normalized as per standard operating procedures and clearance given for light up. 1 14/9/2023 1:30 14/9/2023 3:33 2:03:00 0.4305 FORCED FURNACE PRESSURE VERY HIGH Coal cycle 1C become NCF and immediately 1E NCF @ 01:27 Hrs furnace draft goes to +453 and unit tripped at 01:30 Hrs on furnace pressure very high. Wide range transmitter showed 454 mmwc and all control trans matters were out of range, but this disturbed flame and furnace pressure inside boiler and set tripped on furnace pressure very high protection. System normalized as per standard operating procedures and clearance given for light up.

14. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 15/10/2023 6:20 15/10/2023 9:12 2:50:00 0.602 FORCED FURNACE PRESSURE VERY HIGH Unit tripped on furnace pressure very high due to clinker falling @ 06:20 Hrs. Heavy clinker falling observed. System normalized as per standard operating procedures and clearance given for light up. 1 30/10/2023 11:39 30/10/2023 20:04 8:25 1.7675 FORCED FURNACE DRAFT Set tripped on furnace pressure very high (+350 mmwcl )./ Coal mill A unloaded due to NCF bunker empty. During synchronization AVR exitation supply failed. During synchronization AVR excitation supply failed. Both channels auto/manual faults indication appeared due to suspected voltage dip. AVR normalization and set synchronized 3 1/11/2023 4:28 1/11/2023 8:18 3:50 0.805 FORCED FURNACE PRESSURE VERY HIGH Set tripped on furnace pressure very high. Due to bunker level low (Bunker level – 01 to 02 %). Bunker level not maintained. CHO- 5A under maintenance, single stream operation. System normalized as per standard operating procedures and clearance given for light up.

15. FLAME FAILURE/FURNACE DRAFT UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 4 1/11/2023 10:41 1/11/2023 13:00 2:19 0.4865 FORCED FURNACE PRESSURE VERY HIGH 10:30 Hrs coal mill 4A & 4C both Bunker levels very low. @ 10:40 Hrs coal mill 4A, NCF occurred & set tripped on furnace pressure very high System normalized as per standard operating procedures and clearance given for light up 3 2/11/2023 3:41 2/11/2023 10:42 7:01:00 1.4735 FORCED FURNACE PRESSURE VERY HIGH Set tripped on furnace pressure very high. Due to bunker level low (Bunker level – 01 to 02 %). Bunker level not maintained.  single stream operation. Field breaker servicing done & its faulty trip coil was replaced by E/M, Ckt healthiness checked from testing side clearance given for synchronization.  3 17/11/2023 19:46 17/11/2023 22:22 2:36 0.546 FORCED FURNACE PRESSURE VERY HIGH Set tripped on furnace pressure very high. Before that heavy sound heard due to sudden falling of clinker at firing flour. Heavy variation in furnace draft from – 65 mmwc to + 80 mmwc observed. Also, drum level fluctuation observed & set tripped on furnace pressure very high. System normalized as per standard operating procedures and clearance given for light up 3 29/11/2023 11:07 29/11/2023 13:41 2:34 0.539 FORCED FURNACE PRESSURE VERY HIGH Unit tripped on Furnace Pressure Very High. System normalized as per standard operating procedures and clearance given for light up.

16. ELECTRICAL PROBLEMS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 2 13/4/2023 21:34 14/04/2023 2:35 2:35 0.5425 FORCED ELECTRICAL PROBLEM- SWITCHGEAR PROBLEM At @21:34 hrs 2CA board Tie incomer got off without any command. (2CA was charged from Tie incomer). One air cycle and 3 mills tripped. Also vacuum pump board got off, vacuum not maintained. Hence set was hand tripped. Breaker racked out servicing done and again charged; clearance given. FD fan 2A spring charging mechanism fuse found blown, same replaced, and fan taken in service. System normalized as per standard operating procedures and clearance given for light up. 2 28/5/2023 1:18 28/5/2023 11:23 10:05 2.1175 FORCED SWITCHGEAR- Boiler MCC board tripped Seal air fan 2A, 2B tripped, air heater –2A tripped. Coal cycle tripped on lube oil pressure low. At 00:55 Hrs coal cycle 2A & 2E withdrawn. Seal air fan 2C tripped, FD 2A & 2B withdrawn as both fans lop tripped. Boiler tripped on loss off all fuel. Seal air fan trolly catch tire. Faulty trolly removed. Boiler MCC 2HA bus megger taken found ok. Boiler board charge. 1 27/6/2023 4:06 27/6/2023 12:44 8:38 1.813 FORCED ELECTRICAL PROBLEM- SWITCHGEAR PROBLEM Due to heavy earth fault and overcurrent fault station board feeder to intake and OCA board I/C tripped as fault level was over trip level setting. HT and LT auxiliary, on station PCC tripped. HFO pump tripped. This created turbulence in boiler and set tripped on furnace pressure very high. By isolating source breaker on OCA board, OCA board is charged and subsequently all supply restored except for intake pump house & colony. Faulty disc insulators 2 nos., replaced with new insulators and supply to intake pump house & colony restored. 4 12/10/2023 6:58 12/10/2023 22:44 15:46 3.311 FORCED EXCITATION SYSTEM PROBLEM Unit tripped on Generator protection Reheat protection (Rotor Earth Fault). Hand tripped done on turbine trip. Due to overspeed of turbine. While inspection it was observed that some of brush and brush holders on outer slip ring found completely damaged, out of 30 brush holders, 14 holders were found beyond use/repairable. As no new spare brush holders were available with EM store, 11 Nos of holders from earlier scrap were made ready for use. After completing the work of restoration of brush holders. IR value slip ring checked, found it as 'Zero' MOhms . Further, it was decided to open the rocker assembly to check the problem. On opening one of the rockers assemblies, it was found that one of the broken pieces carbon brushes was trapped inside the rocker body and rotor shaft. After removing the broken piece of carbon brush, IR value of slip ring measured found normal (200M ohms). After complete box-up of rocker assembly, clearance given for rolling and to synchronization that set.

17. ELECTRICAL PROBLEMS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 2 12/4/2023 15:07 12/4/2023 18:30 3:23 0.7105 FORCED ID FAN BEARING TEMP. HIGH Set tripped on ID Fan bearing Temperature very high. Both ID fans tripped on actual temperature rise of DE side bearing. FD Fan 2A breaker work attended (Breaker plug attended). ID Fan 2A DE side bearing replaced by repaired bearing. 2 3/7/2023 23:29 4/7/2023 9:40 10:11 2.1385 FORCED ID FAN PROBLEM Unit withdrawn for Bearing work of ID Fan-2A. ID fan ‘2A’ bearing (D. E. side) replaced. System normalized as per standard operating procedures and clearance given for light up. 2 17/10/2023 4:44 18/10/2023 2:24 21:40:00 4.55 FORCED FD FAN PROBLEM FD fan 2A tripped on motor NDE bearing temperature very high value (@95°). As only one FD fan 2A as available and running &FD fan 2B not available for motor problem since 30/09/2023, unit tripped on both FD fan off. After tripping of FD 2A motor on NDE side bearing temperature high, motor got decoupled from BM. After checking, it is observed that rotor was free. For further inspection, it is decided to remove the motor from foundation and shifted at workshop. On inspection, it is found that NDE side bearing was detached from housing. This insulated housing causing damages to the bearing lock ring and bearing inner sleeve. Said motor sent for repairing on the same day at workshop. FD 1B motor shifted on FD 2A foundation as per the instructions of competent authority. Clearence for light up after coupled trial is given and final light up done on 17.10.2023 at 23:05 Hrs. Set is synchronized on 18.10.2023 at 02:24 Hrs. After repairing, faulty motor is shifted on FD 1B foundation on dated 20.10.2023 and taken in service. 3 14/11/2023 17:40 14/11/2023 18:53 1:57 0.4095 FORCED ID FAN PROBLEM IDF-A both VFD channels tripped thereby tripping ID Fan-A & FD Fan-A. Set tripped on air flow <30 It was found that 220V   aux supply going to VFD channels was interrupted. Upon checking it was found its MCB tripped. Normalized the MCB. Made it ON. Both VFD channels of ID Fan-A normalized & taken into service. No specific work carried out. 2 17/11/2023 10:28 20/11/2023 13:33 75:05:00 15.7675 FORCED ID FAN PROBLEM TA set was running normal with 3 coal cycle and with oil support. Only one ID fan 2B & FD fan 2A available. Unit withdrawn /hand tripped @ 10:28 Hrs , as per declared short shut down of unit.  System normalized as per standard operating procedures and clearance given for light up

18. OTHER TRIPPINGS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 1 15/4/2023 6:30 17/04/2023 6:39 48:09:00 10.1115 FORCED AIR HEATER PROBLEM Unit tripped on Air Heater Problem. Air heater B Driving end gear box found decouple. APH-1B drive end gear box complete assembly replaced by another one. Both APH- internal inspection & repair works carried out. Boiler hydraulic test taken at 150 kg/cm2, found ok. Oil gun tracing line leakage (steam) at EF4 elevation attended. ID fan 1A & 1B casing patching done. 3 27/04/2023 13:39 27/04/2023 18:56 5:17 1.1095 FORCED FIRE HAZARD GCB opened on generator reverse power protection. Suspected faulty operation of fire protection. Suspected faulty operation of fire protection. To avoid it, local push button wires of fire protection cut from CCA04 panel. All cables earthing checked. CCA panel processor card PR05 replaced with another card. Also, processor cards output signal card replaced. As no abnormality observed, clearance given for light up. 3 28/04/2023 1:51 28/04/2023 8:22 6:31:00 1.3685 FORCED FIRE HAZARD GCB opened on gen reverse power protection. unit tripped on faulty fire protection. Unit tripped on faulty fire protection. Detailed checking done again, but no fault observed. Hence again o/P card, processor cards replaced. New EEPROM put in processor to avoid any catch bit problem. Clearance given for rolling. 2 4/5/2023 18:55 4/5/2023 22:25 3:03 0.735 FORCED DURM LEVEL VERY LOW GCB opened on generator reverse power protection. drum level dropped up to -370 mmwc and Unit tripped on drum level very low. FD 10 valve open/ close trial taken for 2 to 3 times. But no malfunction or problem observed. System normalized as per standard operating procedures and clearance given for light up.

19. OTHER TRIPPINGS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 3 10/5/2023 8:21 11/5/2023 0:24 16:03 3.3705 FORCED AIR HEATER PROBLEM GCB opened on gen reverse power protection. Flue gas after Air heater rose above 250°C. APH-3A foreign material at hot end sector plate removed out. Main drive gear box overrunning clutch replaced by another one APH-3A trail taken, found ok. 4 26/5/2023 22:55 28/05/2023 4:39 29:44:00 6.244 FORCED AIR HEATER PROBLEM Air heater 4A gear box problem, set was hand tripped. Air preheater 4A had abnormal sound in gear box and play in vertical output shaft while in service. Hence complete drive unit gear box replaced by spare one. trial found ok. work carried out as per shutdown defect list. LP bypass EHTC coil will be installed up to 2/6/2023 and final trial and characteristic setting will be done during next shutdown in coordination with TIC. Routine primary motor work carried out. 2 29/6/2023 4:43 29/6/2023 8:15 3:32 0.742 FORCED DURM LEVEL VERY LOW Set tripped on drum level very low. During normal condition, drum level DCS processor module PR 03 hanged. Due to this all parameters processed by this module got bad. As drum level not visible, operation staff hand tripped set on safer side. As new processer was not available, same processer made out and in, this resetted it. All parameter checked and clearance given. System normalized as per standard operating procedures and clearance given for light up. 1 29/7/2023 13:24 30/7/2023 19:18 29:54:00 6.279 FORCED TURBINE BEARING VIBRATION HIGH Unit Hand tripped as Low-Pressure Turbine Bearing Rear Side Vibration High. Just after synchronization of generator after AOH, turbine vibration found on higher side as machine was loaded. Hence hand tripped. Low pressure turbine bearing rear side vibration goes up to very high. 81.7 mm. Low pressure turbine both side gland box seal clearance increased. Gland box assembled. system normalized as per standard operating procedures and clearance given for light up.

20. OTHER TRIPPINGS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 2 10/9/22023 10:00 11/9/2023 15:28 29:28:00 6.188 FORCED CHP BUNKERING PROBLEM Set tripped on CHP Bunkering Problem. Suddenly all flame scanner disappeared due to NCF in coal mill 2F & all other mills are NCF/Choke up and unit tripped @ 10:00 Hrs. On drum level very high. System normalized as per standard operating procedures and clearance given for light up. 2 12/9/2023 0:10 12/9/2023 4:41 4:31:00 0.9485 FORCED COAL MILL NOT AVAILABLE DUE TO MILL CHOKE UP Coal mill 2F choke up /NCF & all other coal mill not available and unit tripped on drum level very high. System normalized as per standard operating procedures and clearance given for light up. 4 20/9/2023 0:18 20/9/2023 8:08 7:05 1.645 FORCED CHP BUNKERING PROBLEM Unit was running on only one mill i,e c/m 4E bunker D,E,F were empty. C/M-4A and 4C was U/P oil support was in AB-1,2,3 and CD-1,2,3,4 elevation. At 00:03 C/M 4B NCF. MS temperatre was maintaning low as upper elevation mill N/A. BT position +30, also control valve throttled but after NCF to C/M-4B set tripped wet steam protection System normalized as per standard operating procedures and clearance given for light up. 4 9/10/2023 4:58 9/10/2023 18:27 13:29 2.8315 FORCED AIR HEATER PROBLEM At 04:32 hrs APH 4A stopped due to which it's FG temperature after air heater increased upto 300 degree C so coal mill 4E withdrawn & coal mill 4F minimum 20 TPH. On air motor also APH not rotating tried 2-3 times so unit hand tripped at 04:58 after consulting B/M pr. part Engineer. Air pre-heater-4B overrunning clutch of man drive speed reducer gear box on AC motor side failed. It is replaced by another one by dismantling clutch assembly. APH internal inspection done. Foreign material removed out. Damaged seals replaced. trail taken on AC motor & air motor, found ok. clearance given for boiler light-up.

21. OTHER TRIPPINGS UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS GEN.LOSS (MUs) TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS ACTION TAKEN/WORK CARRIED OUT 4 12/10/2023 23:12 13/10/2023 1:08 1:56:00 0.406 FORCED TURBO-VISORY PARAMETERS Set was running on EHC since temperature margin was not there due to TSC operating mode. Hence HP/IV control valves closed due to throttling action. Because of this, HPT exhaust temperature increased. Hence set tripped HPT exhaust temperature very high. System normalized as per standard operating procedures and clearance given for light up. 3 5/11/2023 19:08 5/11/2023 21:24 2:16 0.476 FORCED DRUM LEVEL VERY LOW Unit Tripped on Drum Level very low at 19:10 hrs. At 18:15 hrs AC compressor tripped on chiller water low pressure due to VFD room AHU-2 chiller line leakage, so AHU-2 stopped & isolated. One A.C. compressor came in service. But other two A.C. compressor not getting on due to chiller pressure low. Informed to I&C @ 19:04 hrs. Drum level becomes bad, feed station valve comes on manual, valve manually operated but not taking command & set tripped on drum level low at 19:10 hrs.  A.C. compressors restored; Durm level faulty card replaced. Temperature normalized. A.C. compressors restored and chiller water leakage attended. 4 10/11/2023 13:48 16/11/2023 20:16 150:28:00 31:598 FORCED AIR HEATER PROBLEM At 13:38 Air heater-A motor Current Increase up to 33 Amp. & Air heater-A rotor stopped indication appeared VCP. Attempt to start air motor drive I/S was failed. Suspected jamming of air heater due to mechanical problem. Boiler hand tripped subsequently TG set tripped. APH-4A support found damaged it is replaced by new. APH-4B support bearing & APH- 4A & APH- 4B guide bearing inspection and oil replacement work carried out. APH- 4A & APH- 4B, Guide & Support Bearing LOP filters and oil cooler cleaning work carried out. Valve, dampers and BT work as per defect list carried out. Sky climber erection and water wall checking carried out. Hydraulic test of boiler taken, found ok.