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1.5 Maintenance of Operating Mechanism
Before carrying out the maintenance of operating mechanism ensure that the breaker is
open, the sequential isolators are open and the closing and opening springs are
discharged.
1.5.1 Maintenance schedule
Sr Description Before start Every 1000
No. Up operations
1. Checking of operating mechanism.
2. Checking of fastener tightness.
3. Checking of shock absorbers for
leakage or struck up.
4. Checking of various tension springs
and bending springs for their proper
place.
5. Closing and tripping spring assembly -
and split pin/ Circlip on them.
6. Bearing items. -
7. Checking of Operation box Assembly
for proper open/close operation.
8. Checking of setting. Proper
engagement of lever on shaft.
9. Spring cut off micro switches.
10. Lubrication of charging device and
operating gear
NOTE
1.
Complete overhaul of circuit breaker operating mechanism to be done after 10000
operation or 10 years, whichever is earlier.
2.
Ask ABB Nasik for details of overhaul procedure.
1.5.2 Trouble shooting guide
FAULT CAUSE REMEDY
Spring does not get
charged
Motor has wrong or no
operating voltage.
Motor shaft broken.
Motor gear damaged.
The latch for the tripping
device does not function.
Disconnection in the
wires.
Micro-switch arm wrongly
adjusted.
Measure voltage on
the motor leads.
Change motor.
Change motor.
Change mechanism.
Check by measuring.
Adjust the micro-
switch operating arm.
PART C Operating Mechanism working principle & maintenance
