Advertisement
PART C Operating Mechanism working principle & maintenance
FAULT
Closing of breaker
does not take place
although there is an
indication that the
springs are
charged.
Breaker
continuously opens
and closes.
1.5.3 Replacement of operating coil
Refer Figs.5 to 8, (page no 55 to 56) indicate the mounting arrangement for closing
coils and the tripping coils.
1.5.4. Replacement of micro-switch Refer Figs. 13 & 14, (page no. 59) indicate the
mounting arrangement for micro-switch.
1.5.5 Replacement of motor Refer Figs.10 to 12,(page no. 57 & 59) indicate the mounting
arrangement for motor.
1.5.6 Replacement of operating mechanism
The operating mechanism shall be replaced in the following manner.
a. Disconnect the linkage of the operating mechanism to the main shall be replaced
in the following manner.
b. Disconnect the electrical connection.
c. Loosen screws that fix the operating mechanism cabinet.
d. Take out the operating mechanism and fix new one.
e. Reconnect the electrical connections and the linkage of the main shaft. After fixing
the operating mechanism the following check shall be carried out.
f. Charge the closing spring.
g. Close the breaker.
h. If required then adjust the micro-switch for proper operation.
i. Check the breakers with the auxiliary supply connect while charging at minimum
operating voltage of the motor.
j. Take few operations for the new mechanism.
k. Seal various lock nuts of various settings with red paint.
CAUSE
Breaker closes then
opens again.
Operating coils does not
operate.
The toggle joints of the
mechanism are incorrectly
adjusted.
Wrong wiring of the
auxiliary circuit.
Wrongly adjusted
clearances of opening
magnets armature.
Anti pumping relay wrong
or faulty.
REMEDY
Measure the voltage
adjust the coils
adjustment screw.
Check the springs.
Adjust the toggle
joints.
Check the wiring as
per schematic
drawing.
Adjust the opening
magnet.
Change relay.
40
Advertisement
