Trouble Shooting of New 415V SW.GR. L&T make

TROUBLE SHOOTING
OF L&T MAKE 415V
AIR CKT. BREAKER.
UNIT-1
This document is prepared for general idea of
Trouble shooting of 415V L&T Make breaker. I am
sharing Switch gear experiences along with my
knowledge with you. Please give me your valuable
suggestions & best support for next version.
2014
MUKESH MISTRY
KAPS-1&2, EMU,
1/4/2014

2
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T CIRCUITCIRCUITCIRCUITCIRCUIT BREAKERBREAKERBREAKERBREAKER
“STAR” Principle must be remembered.
Isolation must be checked.
Personal & Electrical safety must be remembered.
Job must be start with Two Authorized people.
Latest drawing must be used.
Don’t hurry for work start.
Insulated Tools must be used.
Give feed back to your superior.
All events write properly and History fill up.
Work area clean.
PREPARED BY: MUKESH MISTRY, FM/B, EMU M -9408709971 DATE: 01.04.2014 REVISION: 00

3
INDEXINDEXINDEXINDEX
SR.NO. DESCRIPTION PAGE NO.
1. 415V L&T Make Air Circuit Breaker Details 04
2. Name of ACB Parts 05
3. Name of ACB Cubicle Parts 06
4. Name of ACB & Cubicle Parts 07
5. Operation of Breaker 8 & 9
6. Indicator Provided on Front facia 10 TO 13
7. Electrical Operated Circuit Breaker 14
8. Manual & Electrical Charging 15
9. Closing the Circuit Breaker 16
10. Breaker Position - SERVICE , TEST & ISOLATED 17 & 18
11. Procedure of breaker Racking IN/OUT 19 & 33
12. Electrical Anti - Pumping 20
13. ACB - Accessories 21 & 22
14. Micro switches for Indicating position of the breaker on the cradle 23
15. Racking Interlock 24
16. Operation of Micro Switches (Limit Switch) 25
17. Door Interlock 26 & 27
18. Safety Shutter 28
19. Components to be Greased 29 & 30
20. Adjustment of Arcing Contact 31
21. Procedure to be followed for Removing the Front Facia of a Breaker 32
22. “KEY” Interlock in ISOLATED, SERVICE & TEST Position 34
23. Trouble Shooting of Motor Feeder Breaker 35 TO 39
24. Trouble Shooting of Incomer Breaker 40 TO 44
25. Trouble Shooting of Tie Breaker 45 TO 49

4
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T CIRCUITCIRCUITCIRCUITCIRCUIT BREAKERBREAKERBREAKERBREAKER (MOTOR FE(MOTOR FE(MOTOR FE(MOTOR FEEDER)EDER)EDER)EDER)
New 415V L&T Make Air Circuit Breaker Details:
TYPE: CN – CS 1250C
• Rating : 1250 A
• Type Designation : C
• Rated Current (A): 1250A
• Rated Voltage(V): 660V
• No. of Poles: 3
• Breaking Capacity: 50KA, Short Circuit Breaking Capacity: 50KA
• Making Capacity: 105KA
• Opening Time (ms): 40
• Closing Time (ms): 60
TYPE: CN – CS 4000H
• Rating : 4000 A
• Type Designation : H
• Rated Current (A): 4000A
• Rated Voltage(V): 660V
• No. of Poles: 3
• Breaking Capacity: 100KA, Short Circuit Breaking Capacity: 100KA
• Making Capacity: 220KA
• Opening Time (ms): 40
• Closing Time (ms): 60

5
“C” POWER - RANGE OF L&T MAKE ACB

6

7

8
OPERATION OF BREAKER:
Figure – 5.1
MANUALLY OPERATED BREAKERS
ACB closes in single stroke operation of the handle.
Operating sequence of manual breakers:-
Initially breaker is OFF.
1. For carrying out any operation, the breaker-operating handle has to be pulled out fully by holding its top portion.
2. For extra leverage, the handle can be telescoped lengthwise (recommended).
RESETTING:
3. Rotate the operating handle by 90 in anti-clockwise direction (till it becomes horizontal). The breaker will trip at the beginning of
the resetting operation, if it is in closed condition.

9
Figure – 5.2
CLOSING:
4. Rotate the operating handle by 90 in clockwise direction (till it becomes vertical to close the ACB).
5. After completing the operation ensure that the handle is placed back in the cavity on the front facia.

10
An indicator provided on front facia (refer Fig. 5-1) shows the
- RED / ON: ‘CLOSED’
- GREEN / OFF: ‘OPEN’ position of the main contacts.
Operating Handle (refer Fig. 5-2) can occupy either of the two distinct position spaced 90 apart.
- Horizontal Position: ‘OPEN- RESET’
- Vertical Position: ‘CLOSED’ or ’TRIPPED’
Figure-5.3

11
The sequence of operation is RESET? CLOSE? OPEN
Caution:
Resetting the ACB in ‘ON’ condition will cause the ACB to trip.
Precaution:
Ensure presence of supply voltage to undervoltage release (if fitted) before closing the ACB. In case of manual reset type ACB
actuation of TRIP push button / key of lockable trip push button, resets the tripping mechanism of ACB.

12
OPENING THE CIRCUIT BREAKER:
The breaker can be opened by the following means:
LOCALLY (Manually):
1. Press the TRIP push button. OR
2. Press key of lockable trip push button (when provided).
3. Rotate key of racking interlock for draw out breakers (if provided) when the breaker is in any position between ‘Service’ and ‘Test’.

13
4. Operate handle anti-clockwise.
REMOTELY (Electrically):
1. Through shunt release.
2. Through under voltage release.

14
ELECTRICALLY OPERATED CIRCUIT BREAKER:
OPERATION FOR C/S1/H/D - RANGE BREAKER
Initially breaker is OFF and spring is discharged. Spring condition is indicated by a mechanical indicator visible through a transparent
window on the front facia.
Indicator display spring condition
YELLOW CHARGED
BLACK DISCHARGED
The spring in the circuit breaker operating mechanism must be charged to store the energy required to close the main contacts. The
spring may be charged manually using the charging handle or automatically by the motor.

15
Electrical Charging:
The spring is automatically charged & automatically recharged after each closing operation. (Provided there is a continuous supply to
the motor)
Manual Charging:
In case of power failure, charge the main spring through multiple strokes of charging handle. The handle has to pull outward by
gripping its top portion.
Charge by giving small strokes (25) as shown in Figure in the clockwise direction till indicator display
Shows a spring charged condition (yellow colour).
Now the breaker is OFF and spring is charged.

16
CLOSING THE CIRCUIT BREAKER:
(Ensure precautions before closing same as manual ACBs.)
Breaker is OFF and spring is charged.
LOCALLY (Manually):
Press ON push button.
REMOTELY (Electrically):
The closing electromagnet, when actuated, discharges the spring and closes the breaker.

17
RACKING:
Circuit breaker positions
The indicator on the front shows the position of the circuit breaker in the cradle.
Service position: In service position both power and control circuits are connected.

18
Test position: In test position power circuit is open ensuring full safety, while control circuit is connected for checking accessories
as well as breaker operation.
Isolated position: In isolated position both power and control circuits are disconnected from supply to ensure complete isolation.

19
PROCEDURE of Breaker Racking OUT / IN:
1. Racking operation must be done with the aid of racking handle, provided in racking handle
storage location.
2. Insert the racking handle in the racking slot.
3. Rotate the racking handle in clockwise direction to rack in and in anti clockwise direction to
rack out.
4. Remove the racking handle from the racking slot.
5. After completion of racking operation ensure that the racking handle is kept in its correct
storage location.
Note:
I. If the panel door is open, keep the door interlock pin pressed during racking.
II. If racking interlock is provided press the key inwards and turn it clockwise before racking.
Caution:
Open the circuit breaker before racking IN / OUT.
Note: If the breaker is inserted or withdrawn with it’s main contacts in closed position, then a device automatically trips the breaker
before separation of the main isolating contacts(during withdrawal) or before they come into contact (during insertion). The same
device prevents the closing of the breaker at one particular location between the position ’Test’ and ‘Service’.
When racking interlock provided, the key of the lock has to be pressed and turned anti-clockwise (this will trips the breaker if it is in
closed condition at any location between the positions ‘Test’ and ‘Service’) before initiation of the racking operation, otherwise it will
not be possible to rack the breaker in or out. If the cradle is provided with door interlock, ensure that either the door is closed or
interlock is defeated while attempting racking.

20
ELECTRICAL ANTI-PUMPING:
When a closing command is given, closing coil of the circuit breaker gets supply through a normally closed (NC) contact of the anti-
pumping contactor. The closing coil is energized and the breaker closes. The auxiliary contact Q1 of the breaker closes. This
energizes the coil K1 of the anti-pumping contactor and the contactor picks up. This opens its normally closed (NC) contact in series
with the closing coil breaking the persistent closing command. In order to close the circuit breaker again, the closing coil circuit will
have to be reset, which will happen only after the anti-pumping contactor drops off. The contactor will drop
off only when the closing command is removed. This ensures that once the breaker has closed and tripped on fault the breaker can
close again only after the first closing command is removed and a fresh closing command is given, thus providing anti-pumping. The
anti pumping contactor should be selected in accordance with the rating of the closing coil.

21
ACCESSORIES:
AUXILIARY CONTACT: Auxiliary contacts are offered in following combinations:
2 NO + 2 NC
6 NO + 6 NC
Note: Number of aux. contacts available to customers may be less than actual, as some aux. contacts may be used for internal
wiring purpose.
SECONDARY ISOLATING CONTACTS (SIC):
• Self aligned, spring loaded, fully draw out type
• Required for control circuit connections
• Maximum four blocks, each of six contacts
• The contacts are rated at 16A, 500V AC

22
SPRING CHARGING MOTOR: Electrical charging of the main spring can be achieved by using motor.
1. Offered both in AC and DC rating.
2. Spring charging time: 7 sec (approx.)
3. For 415V application, use a 415V/240V transformer rated for 500 VA
4. For DC control applications, the circuit must be wired for double isolation if AC control to DC control conversion is done.
Note: Providing continuous supply to the motor would ensure that the main spring gets charged after ‘Close’ operation and is ready
for the next operation.

23
MICROSWITCHES FOR INDICATING POSITION OF THE BREAKER ON THE CRADLE:
• Electrical indication available through micro switches
• Two micro switches with one changeover contact for
1. Test or Isolated position (C8 & C9)
2. Service (C6 & C7)
• In case of an electrical ACB, a service position micro switch is fitted on the left side as a standard. This can be used to
prevent remote closing of ACB in ‘Test’ & ‘Isolated’ positions

24
RACKING INTERLOCK:
• Before initiation of racking operation, the key of the lock is to be pressed and turned anticlockwise. Otherwise the racking
operation gets mechanically prevented
• In case the breaker is in closed condition, pressing of the key trips the breaker between the Service and Test positions.
• The key remains trapped in the lock when not pressed and this makes it suitable for interlocking.

25
OPERATION OF MICROSWITCHES:
1. Cam on telescopic rail.
2. Micro switch (C8/9) in test or isolated position.
3. Micro switch (C6/7) in service position.
‘Service’ position: The micro switch operates 3 mm before the ‘service’ position
‘Test’ position: The micro switch operates 3 mm before the ‘test’ position during withdrawal
‘Isolated’ position: The micro switch operates 2 mm before the ‘Isolated’ position

26
DOOR INTERLOCK:
Door Open and Breaker in ‘Isolated’ position.
When the door is open, the spring-loaded pin interferes with the screw (refer Fig. 4) and hence the racking screw cannot be turned.
However, when the door is closed, the pin is pressed and the screw is free to rotate. The breaker can be racked now.
• This arrangement ensures that the breaker cannot be racked to the ‘Test’ and ‘Service’ position unless the door is closed.
When the breaker is in ‘Isolated’ position, make sure that the position of the top end of the lever results in its movement in anti-
clockwise direction. Check that on removal of the pressure, the lever comes back to its original position due to spring action.

27
Door closed and breaker in ‘Service’ / ‘Test’ position:
When the breaker is racked in, the pin on the left side plate of the breaker presses the lever as shown in Fig. 5. The rear portion of
the lever rises & comes in front of the latch piece fixed to the cubical door as shown in Fig. 6. The interference between the latch
piece and the lever prevents the door from opening. However, when the breaker is withdrawn to the ‘Isolated’ position, the door can
be opened since the lever is not pressed by the pin of the breaker side plate and hence there is no interference between the latch
piece and the rear portion of the lever. The door interlock can be defeated by rotating the screw on the cubicle door in anti-
clockwise direction using a screw driver.
RACKING INTERLOCK:
Before initiation of racking operation, the key of the lock is to be pressed and turned anticlockwise. Otherwise the racking operation
gets mechanically prevented
- In case the breaker is in closed condition, pressing of the key trips the breaker between the positions ‘Test’ and ‘Service’
- The key remains trapped in the lock when not pressed and this makes it suitable for interlocking.
LOCKABLE TRIP PUSH BUTTON:
This system replaces the normal trip push button by a lockable one and used for the purpose of locking & interlocking. The push
button is suitable for Manual and Electrical, Draw-out and Fixed Breakers of all ratings, which makes interlocking between any
versions and rating possible. The system defeats all positive closing signals (manual / electrical) and prevents nuisance closing of the
locked breakers. The key remains trapped on the push button once unlocked which makes it suitable for interlocking and
gives easy access (if one desires) to lock the breaker.

28
AUTOMATIC SAFETY SHUTTER FOR DRAWOUT BREAKERS:
The shutter automatically covers the cradle terminals (which may be live) once the breaker is drawn out of ‘Service Position’. This is
to avoid accidental contact of the operating personnel with live parts during maintenance.

29

30
Components to be greased:
All rubbing surfaces in the mechanism, poles etc. are to be greased except the contacts (copper on copper) and sintered bearings.
Grease sliding surface of fixed and moving secondary isolating contacts with petroleum jelly. Prior to greasing, these surfaces should
be thoroughly cleaned. Excess grease must be wiped out.
Note: Please do not use any cleaning agent while cleaning with cloth.
Components greased for life
The following components are provided with self lubricating sintered rings impregnated with grease for life.
- Trip rod
- Intermediate shaft of manual control
- Free return charging device for electrical operation
Components not to be greased
- All releases
- Main contacts in pole and cradle terminals
- Earthing terminal
- Secondary isolating contacts
Caution:
Before any maintenance operation, following procedure must be followed.
- Mechanism spring must be discharged.
- Draw out breaker must be in isolated/maintenance position.
- Circuit breaker which operates rarely must be periodically operated.

31
Adjustment of arcing contacts:
Breaker is in ‘Closed’ condition. Move the fixed arcing contacts to obtain the dimension 0.9 ± 0.1 mm between the fixed and moving
arcing contacts.
Tightening couple of the screw (12): 0.8 kg-m
Note:
Check the positioning of the arcing contacts again at the end of the inspection schedule. Gap between the arcing contacts (fixed and
moving) 0.9 ± 0.1 mm. Maximum difference in this dimension for the arcing contacts of the same pole should not be more than 0.1
mm.
Limit of wear = 1.5 mm
Tightening couple of the screws (9) and (10): 0.25 kg-m (moving arcing contact)

32
PROCEDURE TO BE FOLLOWED FOR REMOVING THE FRONT FACIA OF A BREAKER:
For removing the front facia, follow the steps mentioned below:
1. Remove the plug of the operating handle using a screw driver. (See Fig. 10-26a)
2. Get screw (1) fully unscrewed. (See Fig. 10-26b)
3. Remove the operating handle.
4. Get the screws at the four corners of the front facia unscrewed. (Fig. 10-26c)
5. Remove the front facia from the breaker.

33
PROCEDURE FOR RACK-IN/RACK-OUT:
• Before fitting the breaker on its cradle, ensure that the breaker is in ‘OFF’ position.
• Ensure that the closing spring in case of electrically operated breakers is discharged. If it is in charged condition, press the
‘CLOSE’ push button to discharge it and then press the “TRIP” push button to bring the breaker in ‘OFF’ position.
• Rack the telescopic rails out to ‘isolated’ position if necessary & further pull them out to ‘Maintenance’ position.
• The breaker and cradle are fitted with ‘rating error prevention’ feature. This prevents the mismatch of breaker & cradle, as a
breaker having rating other than that of the cradle cannot be fitted on the telescopic rails of the cradle.
• Place the breaker onto the rails and engage with M8 nuts, spring washers and the on the telescopic rail studs.
• Ensure that the breaker is not sitting on the collars of the studs.
• Push the breaker in fully and then tighten the nuts on the two accessible studs.
• Pull out the breaker so as to tighten the inner two nuts.
RACK-IN OPERATION:
• Push the breaker in, until lug engages with spring loaded catches. This corresponds to ‘Isolated’ position.
• Take the racking handle out from its storage location and insert it into the racking screw location.
• Before racking ensure that
1. Key of the racking interlock (if provided) is pressed and turned anti-clockwise.
2. Key of position lock (if provided) is turned clockwise.
3. Pin of door interlock is pressed.
• Rotate the racking handle in clockwise direction until position indicator shows ‘SERVICE’ position.
Note: Alignment of breaker facia with cradle facia indicates breaker is in ‘SERVICE’ position.
RACK- OUT OPERATION:
• Take the racking handle out from its storage location and insert it into the racking screw location.
• Before racking out ensure that
1. Key of the racking interlock (if provided) is pressed and turned anti-clockwise.
2. Key of position lock (if provided) is turned clockwise.
3. Pin of door interlock is pressed.
• Rotate the racking handle anti-clockwise until position indicator shows ‘ISOLATED’ position.

34
Breaker in ‘ISOLATED’ position
• Breaker can be locked & key can be removed.
• Breaker cannot be racked in
Breaker in ‘SERVICE’ or ‘TEST’ position
• Breaker cannot be locked
• Key cannot be removed

35
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T MAKEMAKEMAKEMAKE CIRCUIT BREAKERCIRCUIT BREAKERCIRCUIT BREAKERCIRCUIT BREAKER (MOTOR FEEDER)(MOTOR FEEDER)(MOTOR FEEDER)(MOTOR FEEDER)
SR.
NO.
SYSTEM PROBLEM COMMON CAUSES SOLUTIONS
1. Circuit breaker not closes in “TEST”
position.
1. Fuse: F-18 or F-19 Blown. 1. Incase Fuse is blown. Fuse replaced.
2. Local-Remote switch-S2 is not in “Local”
Position.
2. Put Local-Remote switch is in Local position.
3. Control Switch 52CS (S3) contact not
proper make.
3. Control Switch-S3 contact make properly.
4. Test Position (K103) 75T contacts (13-14)
not proper make.
4. Contact 13-14 make properly of Relay K103.
5. Check “NC” contact (21-22) of Relay K101
for Spring charging.
6. Sliding contact not proper make. 6. Sliding contact proper make.
7. Breaker Aux. switch “NC” contact (Q1-
52B) 17& 18 is open.
7. Breaker Aux. switch “NC” contact (Q1-52B) 17&
18 is making.
8. “NC” Contact (21&22) of Relay 94-KA is
open.
8. “NC” Contact (21&22) of Relay 94-KA is making.
52B) is open or Check Ext. Rest.
9. Breaker Aux. switch “NC” contact (Q1-52B) is
make or Ext. Rest. Replaced.
10. Closing coil is Open/bunt. 10. Closing coil Replaced
11. Breaker not in “TEST” position. 11. Breaker put in “TEST” position properly.
12. Any wire remove/Loose from TB. 12. Same is tight in TB.
13. Stuck Breaker Mech. 13. Breaker Mechanism problem solved.
2. Circuit breaker not Trip in “TEST”
position.
( Tripping Coil – 1)
Position.
3. Control Switch 52CS (S3) contact (2P3 &
2P4) not proper make.
4. Test Position (K103) 75T contacts (43 & 44)
not proper make.
4. Contact 44 & 44 make properly of Relay K103.
5. Test Position (K103) 75T not operated. 5. Test Position (K103) 75T made available.
7. Breaker Aux. switch contact not proper
makes.
7. Breaker Aux. switch contact proper makes.
8. Tripping coil -1 is Open/bunt. 8. Tripping coil -1 Replaced.

36
SR.
NO.
3. Circuit breaker not closes in
“SERVICE” position.
2. Local-Remote switch-S2 is not in “Remote”
Position.
2. Put Local-Remote switch is in Remote position.
3. Service Position (K102) 75S not operated. 3. Test Position (K102) 75S made available.
4. Service Position (K102) 75S contacts (13-
14) not proper make.
5. Check “3C” relay & its contact. 5. Contact make properly.
6. Check “NC” contact (21-22) of Relay
K101 for Spring charging.
52B) 17& 18 is open.
8. Breaker Aux. switch “NC” contact (Q1-52B) 17&
18 is making.
9. “NC” Contact (21&22) of Relay 94-KA is
open.
9. “NC” Contact (21&22) of Relay 94 -KA is making.
52B) is open or Check Ext. Rest.
make or Ext. Rest. Replaced.
12. Breaker not in “SERVICE” position. 12. Breaker put in “SERVICE” position properly.
4. Circuit breaker not Trip in
2. Local-Remote switch-S2 is not in “REMOTE”
Position.
3. Service Position (K102) 75S contacts (43 &
4. Check “3T” relay & its contact. 4. Contact make properly.
6. Breaker Aux. switch (Q1-52A) contact not
proper makes.

37
SR.
NO.
5. Breaker spring charging is not done. 1. Fuse: F-16 or F-17 is Blown. 1. Incase Fuse is blown. Fuse replaced.
3. Spring charging limit switch contact (C&F,
D&H) not proper make.
3. Spring charging limit switch contact proper
make.
4. Spring charging motor bunt. 4. Spring charging motor replaced.
Position.
6. Breaker Aux. switch (Q1-52A) “NO”
contact (23&24) not proper makes.
7. Contactor 94-KA (Anti Pumping)
is not operated breaker in “TEST”
position.
Position.
3. Control Switch 52CS (S3) contact not
proper make.
not proper make.
6. Breaker Aux. Switch (Q1-52A) “NO”
contact 19&20 is not proper make.
6. Breaker Aux. Switch (Q1-52A) “NO” contact
19&20 is make.
7. Contactor 94-KA is Open/bunt. 7. Contactor 94-KA is replaced.
8. Aux. Contactor K101 is not
operated breaker in “TEST”
position.
1. Fuse: F-16 or F-17 is Blown. 1. Incase Fuse is blown. Fuse replaced.
make.
4. Contactor K101 is Open/bunt. 4. Contactor K101 is replaced.

38
SR.
NO.
9. Contactor K104 (97) is not
operated when Trip Ckt. Healthy
push button (S4) is press.
( Trip Circuit Supervision )
2. Trip Ckt. Healthy push button (S4)
“NO” contact 23&24 is not proper
make.
2. Trip Ckt. Healthy push button (S4) “NO”
contact 23&24 is making.
3. Ext. Rest. (R) is open. 3. Ext. Rest. (R) is replaced.
4. Contactor K104 (97) is Open/bunt. 4. Contactor K104 (97) is replaced.
6. Trip coil-2 is Open/bunt. 6. Trip coil-2 is replaced.
10. Latching Contactor K103 is not
operated.
( TEST Position )
75 T
2. Test position Limit Switch (C8-Q1)
“NC” contact (1&2) are open.
2. Test position Limit Switch “NC” contact
(1&2) proper make.
3. Contactor – K103 is Open/bunt. 3. Contactor – K103 Replaced.
operated.
( SERVICE Position )
75S
2. Service position Limit Switch (C6-Q1)
“NO” contact (1&3) not proper make.
2. Test position Limit Switch “NO” contact
(1&3) proper make.
12. Circuit Breaker “OFF” Indication
lamp not Glowing.
H15
2. Breaker Aux. Switch (Q1-52B) “NC”
contact (9&10) are open.
2. Breaker Aux. Switch “NC” contact (9&10)
proper make.
3. Indication Lamp (H15) is fused. 3. Indication Lamp (H15) is replaced.
13. Circuit Breaker “ON” Indication
lamp not Glowing.
H14
contact (15&16) not proper make.
2. Breaker Aux. Switch “NO” contact (15&16)
proper make.

39
SR.
NO.
14. Circuit Breaker “SPRING
CHARGED” Indication lamp not
Glowing.
H16
2. Contactor K101 “NC” contact
(31&32) is open.
2. Contactor K101 “NC” contact (31&32) is
proper make.
15. Circuit breaker “AUTO TRIP”
Indication lamp not glowing
during breaker trip on Protection.
H19
2. Relay – 86X “NO” contact is open. 2. Relay - 86 “NO” contacts is proper make.
16. “BREAKER IN SERVICE” Indication
lamp not glowing.
H17
2. Contactor K102 “NO” contact
(183&184) is not proper make.
2. Contactor K102 “NO” contact (183&184) is
proper make.
17. “TRIP CKT. HEALTHY” Indication
lamp not glowing.
H18
not proper make.
proper make.
18. “RTM” Meter is not working. 1. Sliding contact not proper make. 1. Sliding contact proper make.
3. Control Transformer (T5) 415V/110V is
faulty.
3. Control Transformer (T5) is replaced.
4. MCB-Q2 (Amp -2) is “OFF” condition. 4. MCB-Q2 (Amp -2) is put “ON”.
operated.
(95 for 52 C)
2. Check Breaker Aux. Switch (Q1-52B)
“NC” contact (9&10).
2. Breaker Aux. Switch (Q1-52B) “NC” contact
(9&10) is make.
3. Check Breaker Aux. Switch (Q1-52A)
“NO” contact (15&16).
(15&16) is make.
4. Latching Contactor K105 is Open/bunt. 4. Latching Contactor K105 is replaced.

40
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T MAKEMAKEMAKEMAKE CIRCUIT BREAKER (INCOMER)CIRCUIT BREAKER (INCOMER)CIRCUIT BREAKER (INCOMER)CIRCUIT BREAKER (INCOMER)
SR.
NO.
position.
Position.
3. Control Switch 52CS (S3) contact
(1P1&1P2) not proper make.
not proper make.
52B) is open.
7. Breaker Aux. switch “NC” contact (Q1) is
making.
position.
Position.
not proper make.
contact not proper makes.

41
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T MAKEMAKEMAKEMAKE CIRCUIT BREAKER (CIRCUIT BREAKER (CIRCUIT BREAKER (CIRCUIT BREAKER (INCOMERINCOMERINCOMERINCOMER))))
SR.
NO.
2. Local-Remote switch-S2 is not in “Remote”
Position.
4. Service Position (K102) 75S “NO” contacts
(13-14) not proper make.
52B) is open.
making.
Position.
proper makes.

42
415V SW.GR.415V SW.GR.415V SW.GR.415V SW.GR. L&TL&TL&TL&T MAKEMAKEMAKEMAKE CIRCUIT BREAKER (CIRCUIT BREAKER (CIRCUIT BREAKER (CIRCUIT BREAKER (INCOMERINCOMERINCOMERINCOMER))))
SR.
NO.
make.
Position.
(153 & 154) not proper make.
26. “R” or “B” Phase Indication lamp
not glowing on panel.
1. Fuse: F-19 or F-20 or F-21is Blown. 1. Incase Fuse is blown. Fuse replaced.
3. Check input & output of Voltage
Transformer – T5 & T7.
3. 415V/110V AC
4. Pri. Fuse: F-11 or F-12 or F-13 or F14 is
Blown.
4. Incase Fuse is blown. Fuse replaced.
6. “R” or “B” Phase Indication lamp is
fused.
6. “R” or “B” Phase Indication lamp is
replaced.
27. Aux. Contactor K101 is not
operated.
make.
4. Contactor K101 is Open/bunt. 4. Contactor K101 is replaced.

43
SR.
NO.
make.
operated.
( TEST Position )
75 T
(1&2) proper make.
operated.
75S
(1&3) proper make.
lamp not Glowing.
H15
proper make.
lamp not Glowing.
H14
proper make.

44
SR.
NO.
Glowing.
H16
2. Contactor K101 “NC” contact (31&32)
is open.
proper make.
H19
lamp not glowing.
H17
2. Contactor K102 “NO” contact
(183&184) is not proper make.
proper make.
lamp not glowing.
H18
not proper make.
proper make.
37. Voltages not show in Panel Volt
meter.
1. Panel Volt meter is faulty. 1. Panel Volt meter is replaced.
2. Fuse: F-19 or F-20 or F-21is Blown. 2. Incase Fuse is blown. Fuse replaced.
4. Check input & output of Voltage
Transformer – T5 & T7.
4. 415V/110V AC
5. Pri. Fuse: F-11 or F-12 or F-13 or F14 is Blown. 5. Incase Fuse is blown. Fuse replaced.
operated.
(95 for 52 C)
(9&10) is make.
contact (15&16) is make.

45
415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T415V SW.GR. L&T MAKEMAKEMAKEMAKE CIRCUIT BREAKER (TIE)CIRCUIT BREAKER (TIE)CIRCUIT BREAKER (TIE)CIRCUIT BREAKER (TIE)
SR.
NO.
position.
2. Local-Remote switch – 43LR (S2) is not in
“Local” Position.
3. Control Switch 52CS (S3) contact
(1P1&1P2) not proper make.
not proper make.
52B) is open.
7. Breaker Aux. switch “NC” contact (Q1) is
making.
position.
2. Local-Remote switch - 43LR (S2) is not in
“Local” Position.
not proper make.
contact not proper makes.

46
SR.
NO.
“Remote” Position.
(13-14) not proper make.
52B) is open.
making.
“REMOTE” Position.
proper makes.

47
SR.
NO.
make.
“REMOTE” Position.
(153 & 154) not proper make.
operated.
(95 for 52 C)
(9&10) is make.
(15&16) is make.
46. Spring Charge Aux. Contactor
K101 is not operated.
make.
4. Aux. Contactor 101 is Open/bunt. 4. Contactor 101 is replaced.

48
SR.
NO.
make.
operated.
( TEST Position )
75 T
(1&2) proper make.
operated.
75S
(1&3) proper make.
lamp not Glowing.
H15
proper make.
lamp not Glowing.
H14
proper make.

49
SR.
NO.
Glowing.
H16
2. Contactor K101 “NC” contact (31&32)
is open.
proper make.
H19
lamp not glowing.
H17
2. Contactor K102 “NO” contact (183
&184) is not proper make.
2. Contactor K102 “NO” contact (183 &184) is
proper make.
lamp not glowing.
H18
not proper make.
proper make.

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