Looking for some help. While checking a couple of similar medium voltage (2.3 Kv)motors I noticed a sound that was either arcing or something that sounded similar to it.

Motor 1 - The sound is very localized and directional (radial) at the outboard end.

Motor 2 - The sound is not localized and can be detected at both ends, and is non-directional (can be detected both radial, and axial).

Any thoughts or input would be appreciated.

Denny,

I assume you are talking about ultrasound. If motors are open drip-proof type, then it is possible to have dust or other debris in the windings. This can cause corona and eventually discharge that degrades insulation. I have made this diagnosis on 4160 volt drip-proof motors on boiler feed pumps in a nasty environment.

You could try one of the fancy off-line electrical winding tests (PDMA, etc.) of take motor out of service and clean/inspect/test it.

Walt

Walt,
Thanks for the response and yes, the topic is ultrasound. Sorry about that!

One motor WPI (ODP) the other WPII, both are 400@900/5011LL-2.3Kv GE

Having only limited exposure to using ultrasound on electrical devices (I'm trying to expand my knowledge in this area) I didn't know if I was onto something or not.

Both motors are in critical applications with generally only short outages. Looks like I need to investigate further.

Looks like it might be worthwhile to do some further electrical testing, possibly PDMA.

Thanks again for the feedback.

Denny,

I have measured ultrasound on/around a lot of motors. One instance, a loose coupling bolt was making a lot of noise; in another it was the air intake grill buzzing; and another it was stick pins on sound insulation that were buzzing. My point is that you should be as thorough as possible with ultrasound, and possibly make other diagnostic measurements before taking a machine out of service. You don't want to "cry wolf" when there is no wolf, but you do want to prevent/mitigate an expensive failure.

Walt

Walt,
Couldn't agree more! I definitely want to increase my odds of a correct diagnosis prior to making a call. It's often difficult enough to gain credibility for PdM programs without rushing to judgement.

Thanks again for your input, It's much appreciated!