SINGLE PHASE ROTOR TEST 1

[bufordwon]

Could someone please confirm what the proper precedure is for testing a rotor that is assembled? I always thought it was 10% of nameplate voltage. My co-worker says it should be anywhere from 50-100% nameplate amps. Any comments please? Thanks.

 

[electricpete]

EASA Large Motor Reference states 10-20% of rated voltage.

I believe current should be limited in the range somewhere around 10% although I don't have a reference. Certainly overheating will occur very rapidly due to no internal cooling. Will overheat even at 10% voltage so the test duration should be limited and monitor stator rtd if possible.

 

[acmotorengineer]

electric pete is correct - use the lowest voltage that will give readable current and allow for small variation in current as you rotate the rotor - do the test quickly to prevent heating which will bias the test.

 

[electricpete]

I was just discussing this with a respected repair shop guru. He says that you should shoot for 50% current.

His perspective is that higher current gives increased sensitivity (I'm not sure why that is). It is a tradeoff between getting the highest current you can for a good test and not damaging the motor by overheating during the test.

 

[jbartos]

Suggestion: Visit

http://www.eeco-va.com/\emrs8.asp

http://www.eeco-va.com/\workscope.asp

http://www.lexseco.com/Files/rotorarticle.pdf

etc for more info

 

[GusD]

Hello bufordwon

The greater the applied current the greater the sensitivity will be.You have to weigh the need to find the problem ,if there is one,without destroying the rotor.
You can't kill the patient in the process.
As the previous post suggest the 10 to 20% voltage will suffice.As pete says ,if you can apply 50% without damage to the rotor,you will have better results.
The best approach is to try 10% and see what you get.If you find a fault at 10% you don't have to go any further.Rotor needs work.
I would be very surprised, if you get to 30% and still no indication of a problem.I would think that perhaps you don't have a rotor problem.If you have to go as high as 50%
than it becomes crucial that you monitar temperature rise.99% of rotor problems will be found at 20 to 30% rate.

GusD