Tech Tip: Troubleshooting an Overheating Motor

Video Transcript

Hi this is Paul with a Groschopp Tech Tip.

We occasionally get asked for tips in troubleshooting causes for overheating. Even when the motor matches the application on paper, you can still run into new variables while testing. Here are six common checks to help determine why your motor may be overheating.

First, check and make sure nothing is blocking the ventilation holes. This may seem obvious, but how often don’t we overlook the obvious? The ventilation holes on your motor must be open to allow heat to escape.

Second, check the ambient temperature the motor is running in and the insulation class of your motor. This is typically found on the nameplate. If the motor is operating in an environment warmer than it is designed for, it may overheat because the ambient temperatures make it more difficult for the motor to cool down properly.  

Our third check is to see what duty cycle the motor is rated for. It can be rated continuously, meaning the motor will run long enough to reach its full operating temperature, or the motor can be rated for intermittent duty. This is when the motor is run for short bursts and has plenty of time to cool down between cycles.

Motors need to be run at or below their rated duty cycle in order to avoid overheating. If the motor is run more frequently than its intermittent rating, the motor won’t fully cool down between cycles and will become increasingly hotter with each cycle, eventually overheating.

Fourth, check your current draw and compare it against the motor’s rating. High current draw could be caused by 1) the motor being too small for the application, 2) the motor is the correct size but something in the application is not functioning correctly, or 3) incorrect voltage. Incorrect voltage will cause the motor to overheat in one of two ways. If the voltage is too low it makes the motor draw more current causing it to overheat. If the voltage is too high it will saturate the steel or cause the motor to run too fast, both of which can cause the motor to draw excess current and then overheat. Note that current draw issues typically need to be extreme to cause your motor to overheat.

Fifth, consider your elevation. Motors cool less efficiently at higher elevations due to the thinner air. If your motor is operating at a higher elevation—3300 ft. above sea level or higher—contact your supplier to see that your motor is rated accordingly.

Finally, as stated before, check that the motor you are using is properly sized for the application. A motor that is too small will not be able to dissipate heat quickly enough, causing it to overheat. This seems simple, but we know that changes are made in the design process, and upgrading the motor size can be an overlooked step.

If you have completed all of these checks and the motor continues to overheat, it’s time to contact your motor supplier for additional assistance.

This has been a Groschopp Tech Tip. For more information about any of our products or to view other Tech Tips please visit us online at www.groschopp.com.

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