Gaussmeter to verify motor field problem 1

[Sofistioelevib]

Hello,
i heard about possibility to make some measurements with gaussmeter (or similar) to check about winding condition of the motor,
anyone have experiences about it?
Could be usefull more than vibration analysis for electrical poiint of view?

Could you suggest some device to try?

Regards

 

[electricpete]

Whatever you are talking about is not in common use.

Maybe you can give some more details.

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[Sofistioelevib]

@electripete
i saw an SKF instrumentation (but i'm not certain) moving on rear of the motor to evaluate the magnetic flux of it but i don't remember details

 

[electricpete]

SKF has a gizmo that claims to tell you something about whether the electromagnetic environment is bad for your bearings, especially on a vfd motor.

https://www.skf.com/us/products/con...ucts/electrical-discharge-detector/index.html

Is that what you're talking about? We have a resident expert skogsgurra who knows a lot of related background (search his old posts)

Btw that device is not monitoring winding condition.


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[Strong]

I have and occasionally use a Flux Coil from CSI (now Emerson-CSI) that is placed on the motor case and detects the flux field. Spectrum analysis can reveal electrical faults similar to (but not identical) motor current spectrum analysis. The Flux Coil can supplement vibrations, current, and sound spectrum analysis for machine diagnostics.

Walt

 

[Sofistioelevib]

@strong
Exactly what i need, can you share here your experience with?
Do you think good help in electric problem?
What fault type this technology can reveal?

Regard

 

[Strong]

For your reading pleasure:
Search: motor flux sensing coil

https://www.bing.com/search?q=motor+flux+sensing+coil&FORM=HDRSC1

Search: csi motor flux coil

https://www.bing.com/search?q=csi m...-19&sk=&cvid=1DE99B34621C42CB871A5E93A650D1DE

https://www.maintenance.org/fileSen...3/fodoid/399590942964868191/State_of_Flux.pdf

Walt

 

[electricpete]

Do you think good help in electric problem?

Personally, no.

Looking at [link file:///C:/Users/schimppw/Downloads/State_of_Flux.pdf]the CSI paper[/url], what are they trying to detect?

The tests were designed to evaluate turn-to-turn shorts, of differing severity, and changes in voltage balance (for the 50 hp motor only) at different sensor locations about the motors

Shorted turns - with very few exceptions (there are a few isolated exceptions I've heard of on ungrounded system random wound machines), shorted turns progress generally progress quickly due to autotransformer effect causing large heating leating quickly to ground fault and motor trip. It's not very useful to monitor for something that will be apparent within a few seconds after you detect it.

Unbalanced voltages. I'd rather measure the voltages or compare the three phase currents. Failing that, vibration twice line frequency would probably increase (and I monitor vibration anyway, for reasons that are much more useful, like bearings). But I wouldn't want to have to get into the business of evaluating every vibration or flux change that might indicate voltage unbalance, unless there was some overheating, tripping, or abnormal currents noted.

The linked paper seems to be a research type paper. It's dated 2009, yet many years later this monitoring approach hasn't taken off for induction motors (something similar is used for shorted turns on sync generators I believe... big difference is that sync generator rotor circuit shorted turns can last a long time since the rotor circuit is dc and not subject to the autotransformer effect as induction motor stator). I don't see prominent mention (marketing) of flux monitoring technology in the literature of Emerson (successor to CSI) although they do provide a compatibility for gathering this data within their AMS condition monitoring software. Sensitivity depends on sensor location.

Color me skeptical.



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[Sofistioelevib]

@electripete
yes this is what i want to understand.
This technique is already used?
It is really usefull as i think?
Are commonly use in a investigation techniques?

 

[electricpete]

This technique is already used?
Are commonly use in a investigation techniques?

My full time job for the last 19 years is overseeing a program for monitoring / maintenance of plant electric motors. I haven't seen this method used.

It is really usefull as i think?

My opinion, no. I tried to explain why in my previous post.



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