TRIPPPING REPORT PRESENTATION FY 2023-2024

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 0 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

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
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
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
8 7/3/2023 23:29:00 7/4/2023 09:40:00 10.11 2.138500 FORCED ID FAN PROBLEM 10:11
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
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

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
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
20 11/21/2023 12:00:00 11/23/2023 24:00:00 60 12.600000 FORCED BTL - ECONOMISER ZONE 60:00
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
3 6/5/2023 16:40:00 6/5/2023 18:54:00 2.14 0.469000 FORCED FURNACE DRAFT 2:14
5 9/20/2023 00:18:00 9/20/2023 08:08:00 7.5 1.645000 FORCED CHP BUNKERING PROBLEMS 7:50
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
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

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

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.
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.
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.

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
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.

BTL
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. 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.

BTL
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.
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.
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.

CARD FAILURE & DCS
OUTAGE
HOURS
GEN.LOSS
(MUs)
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.

FLAME FAILURE/FURNACE DRAFT
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.

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.

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
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
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
.

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.
standard operating procedures

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.
operating procedures and clearance given
for light up.

UNIT NO. TRIP DATE TRIP TIME SYNC.DATE SYNC.TIME OUTAGE HOURS
GEN.LOSS
(MUs)
TRIP TYPE NATURE EVENT ROOT CAUS ANALYSIS
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
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.
standard operating
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
given for light up.

ELECTRICAL PROBLEMS
OUTAGE
HOURS
GEN.LOSS
(MUs)
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.

ELECTRICAL PROBLEMS
OUTAGE
HOURS
GEN.LOSS
(MUs)
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
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.
procedures and clearance given for light up

OTHER TRIPPINGS
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.

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.
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

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.
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.
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
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.

OTHER TRIPPINGS
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.

TRIPPPING REPORT PRESENTATION FY 2023-2024

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TRIPPPING REPORT PRESENTATION FY 2023-2024