Electric Motor Failure

Electric motor failure stems mostly from damaged bearings or stator windings. However, there are a number of other reasons they can fail.

The most common failures in order are:

  1. bearing failure
  2. stator winding failure
  3. overheating
  4. power supply anomaly
  5. humidity
  6. contamination
  7. unusual mechanical loads

Bearing Failure

The main reasons for bearing failure are:

  • improper lubrication
  • electrical discharge across the bearing

Stator Winding Failure

Electrical insulation deteriorates at a rate that doubles for every 10°C increase in temperature.

Overheating

The reasons for overheating are numerous and include:

  • overloaded
  • too many starts
  • high ambient temperature
  • coolant failure
  • low or unbalanced voltages

Power Supply Anomaly

  • harmonics
  • over-voltage
  • under-voltage
  • voltage unbalance
  • voltage spikes

Humidity

If the motor is stopped and cools down it may drop below the dew point. Moisture weakens the insulation and contributes to bearing corrosion.

Contamination

This results in: abrasion, corrosion and overheating. Small particles in the windings can gradually wear the insulation away as the wires flex during operation.


Electric motor failure is a large subject area with specialist knowledge required in a number of disciplines to enable a robust design to be made. We would welcome contributions from hobbyists, researchers and commercial organisations alike. Drop us a line at editor@glue-it.com

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