Dissipation Factor Tests

[Addy71]

I have been doing tan delta testing of motors for many years now. While there are standards for new coils, I am yet to come across any standard for the complete motor. Also, never seen any limiting values for old motors. Does anybody have some references?

Regards,

Aditya

 

[electricpete]

Doble has a large database of rotating machine power factor tests. It's available to those who rent Doble analysers.

I'm in the middle of a move and stuck away from my references.

Doesn't IEEE286 address complete motors?

I think some more repair specs may specify general power factor limits for assembled motors: EPRI 1000897 (available to EPRI members), ANSI spec for power plant motors, possibly EASA AR100?

As you know the power factor and tipup results can be difficult to interpret for 6kv and above due to presence of end winding voltage grading tape/coating which cannot be guarded out while testing assembled motor.



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[Addy71]

Hello Electricpete,

Thanks for the lead. I was able to purchase the IEEE standard on-line. I went to the EASA website, could not find the AR100 document anywhere. Do you have a link?

Based on the other material I have been collecting & my field experiences, I have some opinions. Would like to hear your views:

1. High tan delta could be due to either moisture, aging or improper consolidation of the insulation.

2. High tan delta tip-up is indicative of voids in the insulation.

3. High capacitance tip-up is indicative of partial discharges.

4. Negative tip-up is indicative of grease or oil contamination.

Regards,

Aditya