Motors and Voltage Imbalance, Part 2

July 8, 2014
A good power monitor implementation strategy can help you see these imbalances emerging, but what if you already have a toasted motor and suspect voltage imbalance?

Voltage imbalance in motor circuits causes premature motor failure. The real cost isn’t the motor, but the lost production. A good power monitor implementation strategy can help you see these imbalances emerging, but what if you already have a toasted motor and suspect voltage imbalance?

First, see how widespread the imbalance is. Do you see it only on that motor circuit, at the service, or propagating from some point between the two? Unless it’s at the service, the utility isn’t the problem. If it is at the service, contact the utility for help in troubleshooting upstream of there.

Usually, an imbalance arises from within the facility, and it’s nearly always due to improper allocation of single phase loads. But it could be due to other causes. For example, suppose you have poor connections in your premises wiring and they just happen to add up to a large impedance on one phase relative to another phase; this will give you an imbalance. Properly done resistance testing can reveal where these are.

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