How to Troubleshoot a 3-Phase Electric Motor

How to Troubleshoot a 3-Phase Electric Motor
Written By
DR
Daniel Ray
Published: Dec 2, 2008
Updated: Nov 20, 2021
2 minute read

Because of their industrial use, if they are receiving the correct voltage, they are normally quickly replaced or sent to be rebuilt rather than being extensively troubleshot. Follow the steps below to check for the most common problems for three-phase motors.

Things You Will Need

  • Common hand tools
  • Volt ohmmeter with probes
  1. Take input voltage to the motor using the volt ohmmeter. The motor-specified voltage must be present on all three phases. If not, check supply circuitry, breakers and condition of the motor's power cord. If the voltage is good, go to Step 2.

  2. Examine the motor's electrical connections and terminals. Remove power to the motor and repair any damaged or loose connections.

  3. Remove motor voltage and disengage the motor from the machine that it is running. Reconnect motor voltage and see if the motor now runs. If it does, check the machine for serviceability. If not, go to Step 4.

  4. Check the motor for heat or burnt smell. Clean motor windings and housing with shop air or vacuum and then try to restart. Replace motor if it will not restart.

The Drip Cap

  • Three-phase motors are normally used in commercial-type operations.
  • These motors have fewer parts and are more sturdily built than their single-phase counterparts.
  • If not, check supply circuitry, breakers and condition of the motor's power cord.
  • Replace motor if it will not restart.

Resources

Photo Credits

All images and illustrations by Dan Ray

All images and illustrations by Dan Ray

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