# Testing resistance with a load



## EROD (Aug 3, 2009)

What would be an acceptable way to get an accurate reading for resistance with voltage applied? Tested from a 208 v motor.

And would readings from the capacitor also be possible?

Thanks.


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## drsparky (Nov 13, 2008)

Use ohms law.


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## EROD (Aug 3, 2009)

I know what the stated resistance is.

I want to test the resistance on the operating motor. I want to see if there is a change in impedance.

This may help. I work on large Printing presses. Certain components are difficult at best to get to.


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## Zog (Apr 15, 2009)

EROD said:


> What would be an acceptable way to get an accurate reading for resistance with voltage applied? Tested from a 208 v motor.
> 
> And would readings from the capacitor also be possible?
> 
> Thanks.


Resistance of what? The insulation? The windings? Something else?


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## drsparky (Nov 13, 2008)

Check voltage while the motor is running, preferably with a RMS voltmeter, monitor amplitude at the same time. Divide voltage by amplitude. You now will have resistance while the motor is running.
Ohms law R=E/I


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