Page 183 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

3 Measure the insulation resistance between the winding and the stator core with 500.V megger and record it.
4 Measure the insulation resistance between the winding with a 500.V megger and record it.

The resistance value should not be less than one mega ohm in any case.

5 preheat the winding to a temperature of 100 degree and impregnate the winding with varnish, if the megger
value is less than one mega ohm Dry the varnish slowly either in impregnating bath or open air.
6 Remove the bearing using bearing puller.
7 Check the bearing for its condition.
8 replace the bearing with same number, If the bearing has any abnormal sound or damage

9 Clean the shaft and inspect for any wear or tear.
10 Heat up the new bearing and insert the same in shaft with a slight push. Check the squirrel cage rotor for any
abnormalities.

TASK 3: Reassamble the dismantled motor
Follow the steps of Task 1 in rever order to reaasamble the motor. get it checked by the instructor.
1 Fix the end cup of non-drive end to the bearing and shaft accordingly to the punch mark.
2 Insert the rotor to the stator.

3 Fix the non-drive end shield and tighten all the bolts.
4 Rotate the shaft by hand to check whether it is freely moving.
5 Connect the capacitor in position.

TASK 4: Test the motor in no-load condition

1 Test run the motor for at least eight hours in no load.
2 Note down the no load current.
3 Check for any abnormal sound and temperature rise.

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CITS : Power - Electrician & Wireman - Exercise 75