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Measuring Motor Winding Resistance

Measuring Motor Winding Resistance

Saturday, August 6, 2022 4 Wire Resistance testing motors

4 wire Probes vs Clips, which is better?

Resistance Meter comparison with Clips vs Probes

I have purchased a set of 4 Wire Resistance Probes because using Clips is impossible to use on Screw Terminals. Also the Clips are very difficult to use on smaller motors in getting the clips to sit flat.

So is there a difference?

Measurement with small clips 2.9167 Ohms

Measured with Probes  2.9170 Ohms

As you can see I didn’t measure in the exactly the same spot but both were on the terminal posts.

The difference 0.3 milliOhm for this motor. 0.01% Difference.

I’m happy with that. Problem Solved for measuring Motor Winding Resistances and Circuit Breakers.

Note: When Motor size exceeds 75kW the winding resistance is typically below 10 milliOhm

Therefore a meter in the milliOhm or MicroOhm range will detect an imbalance in resistance

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