Using Inductor and Clamp Meter to Determine Electric Motor Overheating: Correct Current Values?

Question

Hello all. My question concerns the methods of checking electric motors with the use of basic instruments, i.e. an inductor and a clamp meter, at the moment he has these devices. I know that when using an inductor, you can check the impedance between individual coils and between the coils and...

bonanza · Accepted Answer

What I meant was that the phase-to-phase dispersion was 5% and the no-load current could probably be 40-60% or wider.

retrofood · Accepted Answer

Check with the inductor the insulation resistance of the windings to the housing (you can all together). If it exceeds 1 MOma (for a minimum of 60 seconds !!!), then after switching to normal voltage, check whether the no-load currents on individual phases are equal. If so - replace the bearings. And that's it.

bonanza · Answer

Something like 50% of the rated current. And it should be the same on 3 phases (+/- 5%).

Krzyś33 · Answer

If you write about an inductor, you don't measure the impedance, but the resistance of the windings. (yes, in order to be correct). Greetings.

retrofood · Answer

Resistance isolation windings.

Roha · Answer

Check the insulation resistance between the windings and between each winding and the body (casing).

Anonymous · Answer

You supply it with undervoltage (for safety) and measure the current in each of the phases.

stomat · Answer

A burnt engine is very easy to spot with your nose.

dragunow · Answer

Thanks gentlemen for valuable tips :)

In summary, with an inductor we measure the resistance between the individual coils and the resistance of each coil separately between the motor body.
As for the measurement of the idle run, the rated current should be approx. 50% of the rated value +/- 5%.
Anyone want to add anything else ??

tolkien1980 · Answer

The winding insulation resistance can also be measured with a digital meter in the 200Mohm range. The meter should show no value (ideally).

Anonymous · Answer

But this measurement also sucks - an open circuit may come out, but I connect the motor to the network and a magnetic field will arise, which affects the coil, it will bring it to the stator; I fell for it more than once.

retrofood · Answer

Anyway, what and why do you need it? Why don't you write anything about it?

dragunow · Answer

And I'm already improving. I have an engine from the so-called recovery that worked in the lumber dryer. The motor was pulled off because the bearings started to rumble strongly.
Well, but due to the difficult working conditions, i.e. moisture and temperature of about 80 ° C, I would like to be sure whether it is worth regenerating it, i.e. replacing the bearings and seals? Can such an engine still be used and how to check it?

robokop · Answer

And wouldn't it be easier to connect the motor to the mains for a few minutes and watch the temperature rise? Phase current imbalance at idling speed can occur and does not necessarily indicate a motor fault.

retrofood · Answer

In case of any suspicions, it is better (safer) to deal with the insulation resistance first. It's two minutes of work.

dragunow · Answer

Ok thanks for helping everyone. I take care of the measurements and the possible replacement of the bearings. I consider the topic closed.

gruniu · Answer

I found this topic, so I'm not starting a new one. How to check a single phase motor?

Using Inductor and Clamp Meter to Determine Electric Motor Overheating: Correct Current Values?

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