Hi all,
Is there anyway to detect for current leakage? And is there any specific peaks i should look for in a vibration spectrum? Doesn't all electrical problems relate to 100Hz? Thanks!

You can measure current with a good DMM.

Mostly current is synced at either 120 Hz (USA) or 100 Hz (EU) with poling fundamental of 60 Hz and 50 Hz respectively. In the USA we point a photo tach at a floursent light and check calibration at 7,200 RPM or 120 HZ. Out power plants operate at 3,600 RPM basically and/or produce 60 Hz power output regardless of RPM. You can take it from here.

the current leakage is normally detected in DC motor or motor with VFD as a failure in inner ring or outer ring bearing depending the leakage type.
a alternative is use isolated bearing.

can you clarify what you mean by "current leakage"

quote:

Originally posted by electricpete:
can you clarify what you mean by "current leakage"

Hi Electricpete,
I am not so sure on what current leakage...I was informed by my OEM, Siemens, that my DE AC induction motor bearing was damaged due to current leakage... The lifespan of the bearing is a mere 1 month... and upon inspection, the bearing grease looks burned...As far as i know, a bearing damaged from current leakage looks blueish and has diagonal scratch marks across the bearing outer race. The SKF analyst however isn't too sure that the bearing is damaged due to current leakage. I actually do a bit of vibration monitoring and i only got the BPFO fault frequencies from the said bearing...Is there something i missed out from the vibration spectrum and is there any significant peaks when it comes to current leakage? How many types of current leakages are there?

quote:

Originally posted by Sam Pickens:
You can measure current with a good DMM.

Mostly current is synced at either 120 Hz (USA) or 100 Hz (EU) with poling fundamental of 60 Hz and 50 Hz respectively. In the USA we point a photo tach at a floursent light and check calibration at 7,200 RPM or 120 HZ. Out power plants operate at 3,600 RPM basically and/or produce 60 Hz power output regardless of RPM. You can take it from here.

Hi Sam,
I do not really understand your statement earlier on regarding "DMM". Is there any literature on this?

DMM

"Digital Multi Meter"

Dave

A simple thing on a motor is: I have a short piece of welding lead w/~1/2" insulation cut off and use it as a brush against the motor's shaft while running. You can check bleed or current draw, voltage, etc.... If it exists, it shouldn't!

Sounds to me like we're talking about EDM here. Try this link to the CSI website for a paper on what causes it and how to recognise it.

http://www.compsys.com/drknow/aplpapr.nsf/06b6f5a4de2ea...062f412?OpenDocument

Hi all,
Thanks for all your feedbacks...I will look into the matter as soon as possible and reveal the results in due time....

Thanks again

hi wookp, SKF have many information of current leakage.

http://www.skf.com/portal/skf/home/aptitudexchange?cont...237983.238008.238223