Interruption Symptoms - Motors

Motors have enough mechanical inertia to ride through momentary interruptions. However, they are sensitive to longer losses of power.

Temporary interruptions may cause variations in torque, speed or slip. For motors that require steady speed control, these variations can disrupt operations. If the interruption lasts long enough, the motor can slow to the point that, when the voltage is restored, it is out of phase with the motor. This can lead to severe problems and possible motor failure.

Most motors will fully spin down during a sustained interruption. Other than loss of operation and possible indirect loss of product or productivity, the motor should not be damaged.

Because these types of interruptions exist, many customers use breakers and relays designed to open during an interruption. This helps prevent possible or further damage to the motor or to the process the motor is powering.