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JoeVibe

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One of our offices is looking for MCE testing on a chiller motor and the sub they are talking to said "the PDMA tester tends to generate false positives with 2 pole motors.”

I don't do MCE testing myself, but I've been around it for a long time and I've never heard this before. Is there any validity to it or can we assume the tester doesn't know what he's doing?

Thanks,

Joe
John from PA

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You should probably the thread at http://www.eng-tips.com/viewthread.cfm?qid=10535 but keep in mind it is 15 years old.  Like much diagnostic equipment, the interpretation of data is very operator dependent.
JoeVibe

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Thanks John. This job is in Connecticut so I'm trying to help long distance. We had a MCE set up in the motor shop I worked at before moving to Trane but that was 15+ years ago. I thought the winding testing was pretty good back then but I didn't think much of the RIC test they had for rotors. Since they now have the Emax unit that can pull a current spectrum for rotor bar analysis I'm more confident that we can get good data. But as you and I both mentioned, operator competency is going to be key.

I've searched around and I can't find anything to indicate problems testing 2 pole motors, and I really don't see why this would be any different than any other motor. I suggested that our office check local motor shops to see if they can find someone truly experienced with this testing.

electricpete

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 "the PDMA tester tends to generate false positives with 2 pole motors.”
I haven't heard of that, but that doesn't mean much. Do you know if he was referring to pdma on-line test (which is the same as most others monitoring pole pass sidebands around LF, plus additional frequency bands checked) or the RIC test?
Walt Strong

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Here is an alternative product and service based in Connecticut that may be worth contacting:
https://www.alltestpro.com/

I do not own their product or represent them in any way.

Walt
JoeVibe

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Reply with quote  #6 
Quote:
Originally Posted by electricpete
 "the PDMA tester tends to generate false positives with 2 pole motors.”
I haven't heard of that, but that doesn't mean much. Do you know if he was referring to pdma on-line test (which is the same as most others monitoring pole pass sidebands around LF, plus additional frequency bands checked) or the RIC test?


Hi Pete,

I'm honestly not sure if they were talking about a specific test or just making a general statement. I was asked to look at some vibe data and then this came up. I told or office that if the guy doing the testing said this, I'd look for someone else. I referred them to MTI, who's in their neighborhood, but I've not heard anything since. This happens to me a lot, where I'm asked for some help and never hear the end of the story. I guess that's partially my fault because I'm usually too busy to follow up.

Merry Christmas,

Joe
JoeVibe

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Reply with quote  #7 
Quote:
Originally Posted by Walt Strong
Here is an alternative product and service based in Connecticut that may be worth contacting:
https://www.alltestpro.com/

I do not own their product or represent them in any way.

Walt


Thanks Walt! I'll pass this along.

Merry Christmas,

Joe
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