Tests on MV motor

[cherry2000]

We have four 13.8kV, 8000HP motors which were shipped to pump vendors two years back. They have been lying idle since then. These were manufactured as per API 541.
The time has come to ship these motors to site.

Now the query :
What are the tests to be performed to gauge the healthiness of the motor?

In my opinion, this is equivalent to preventive maintenance tests, only with the exception that these motors were never in service.

Please give your suggestions.

 

[rbulsara]

I would follow NETA-ATS (acceptance tests) as a guide plus the motor manufacturer's recommendations!

Rafiq Bulsara

http://www.srengineersct.com

 

[electricpete]

Minimum: Megger/PI testing and winding resistance test.

Rotate and check for roughness. Check T.I.R. of shaft extention.

Drain and inspect oil prior to moving the motor if you have oil bearins. Flush

Think about: DC step voltage test by competent personnel (it is potentially destructive test but imo with proper test voltage the motor is unfit if fails DC step voltage test).

Really nice: Run it on a test platform prior to installing. That is a lot of work and money. But there are things that can occur during storage such as bow or bearing brinneling that probably may not show up without it. It is a tradeoff risk vs cost. How painful is it to find a problem during uncoupled run after installation... sometimes that is no worse than finding it in the shop... sometimes it is completely unacceptable.


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[rbulsara]

I hope these motors were periodically rotated. If they sat idle in one state, it may have sustained mechanical damage e. g. to bearings or shaft may have sagged. (mechanical folks can chime in)

So do not forget mechanical tests. That is why manufacturer's recommendations is paramount.

Rafiq Bulsara

http://www.srengineersct.com

 

[cherry2000]

The motor manufacturer's guide suggests : Insulation Resistance, PI, DC High voltage tests.
For mechanical tests, they suggest manual rotation ( 10 rotations), if possible, and checking of bearings.

Thanks for the suggestions.