When the New Motor Draws Too Much Current, Part 1

Feb. 9, 2015
Your new motor draws more current than the table in the repair procedure says it’s supposed to. Oops. Now what?

Your motor repair procedures require you to measure the running current after installing a new motor. This test is usually such a yawner that there’s been talk about eliminating it from the repair procedure. But now you see why this step was included. Your new motor draws more current than the table in the repair procedure says it’s supposed to. Oops. Now what?

Don’t yank that motor back out, just yet. First, check the motor nameplate and see if it provides the no-load current spec. If not, contact the manufacturer for this information. It could be this particular motor simply draws more current in a no-load condition and there’s nothing wrong.

Check the supply voltage; maybe you have low voltage or voltage imbalance, either of which would have contributed to the early demise of the motor you just replaced. Use a power analyzer to look for other supply problems.

In Part 2, we’ll look at what might be causing this if the replacement is a rewound motor.

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