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Electrical Testing
Three Phase Industrial Motor

Tip of the Week: Motor Overcycling

Restarting a motor too many times within a short timeframe can permanently damage it.

Restart a motor too many times within a given period (say, 30 minutes), and you can permanently damage it. The reason is excess heat. Because of inrush current, each start of a motor generates far more heat than when the motor is running. While the motor is running, it cools down from the temporary “high temperature” condition that starting produces.

Temperature monitoring on a motor is excellent for maintenance purposes, because (for example) you can see whether the motor is trending hot and thus know something is wrong. But temperature is an inherently slow process variable; there is always a lag, so you never know for sure exactly how hot things are just by looking at a temperature gauge.

You can find general restart guidelines by contacting the manufacturer of the motor. Modify those based on actual conditions, such as poor air circulation or high ambient temperature.

TAGS: Motors
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