How to Check AC Motor is Faulty

It is adequate in most cases but if the fault manifests only if the motor is supplied by AC lines,using a clamp meter will help, look at the nameplate to see if the motor draws higher current than specified. Also, a megger tester will surely find where the fault lies.

A qualified electrician should train you to use the megger. Motor damage can result from improper connections and you don't want to learn the hard way about it's high voltage output!

What?

& my GA goes to post #2

Dear Guest,

I agree with post # 2 and would like to add this also. ( 1) Are the winding

resistance equal ? (2) Is the megger value is above 500 M ? (3) Is the motor is

free to rotate ? Check the starting and running currents for any abnormal variations.

Manroop. Chennai.

dear,

NO. This is not enough. Some times, internal turn fault or winding insulation failure during run conditions, but showing normal condition in cold start, does not reveal your mentioned tests.

If motor runs in a reverse direction / motor speed is slower thern rated / without blowing the fuses also indicates the winding fault.

You may measure the resistances of the windings of each phase, that shall reveal the result , for that, you need to keep the winding resistance data at the time of commissioning of the motor equipment.