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1. HOW TO CHECK 3 PHASE MOTOR WINDING WITH MULTIMETER HOW TO
2. HOW TO CHECK 3 PHASE MOTOR WINDING WITH MULTIMETER FULL

You might find that a cold test does not conclusively show a definate ground fault but the hot test shows a clear ground fault. The most common failure mode of a 3 phase AC motor is burnt winding or shorted winding leading to the damage of the motor. If you find a compressor like this try doing a mega test with the compressor cold & then heat the compressor shell up & then mega test again. Some times when motor windings start to fail to ground it will only happen under load conditions & the motor windings have heated up to expose the winding damage. So now you are sure the motor windings have ground fault. So you do another mega test & this time find less than 1 meg ohm. After a few seconds it trips the power supply again. Multi meter shows all 3 windings open circuit so no ground fault. You might just get some resistance reading on a standard multi meter at 1 meg ohm reading from a Mega meter test.Īs an example, you might go to site to invetigate why a compressor has tripped the power supply mcb. Remove motor voltage and disengage the motor from the machine that it is running. IN the Motor Winding end wire in 3 phase A1A2, B1B2, C1C2 connected thro RYB the motor will run But if any changes in the terminal connection A2A1 / B2B1 / C2C1 if the motor winding will get Abnormal heat. Examine the motor’s electrical connections and terminals. The motor-specified voltage must be present on all three phases. Take input voltage to the motor using the volt ohmmeter.

HOW TO CHECK 3 PHASE MOTOR WINDING WITH MULTIMETER HOW TO

On alot of air conditioning compressors up to say 10hp a good motor will show 20 to 40 meg ohm. How to Troubleshoot a 3-Phase Electric Motor. Typically you are looking for a reading higher than 1 meg ohm. This is much more accurate as it effectively tests the windings under load. The motor will still develop a rotating field and still start.

HOW TO CHECK 3 PHASE MOTOR WINDING WITH MULTIMETER FULL

This slams 500v or 1000v through the windings. However if you have a delta connected motor and you remove one of the internal phases, then you still have the full 3 phases connected to the remaining windings, and you still have a 120 degree phase difference in the currents flowing through the remaining winding.

To properly test the motor windings you must use a Mega meter. The reading should be completely open circuit. Measuring resistance of each winding terminal to earth on 3 ph compressor motor with a multi meter only gives you an aproximate indication.