Sags & Swells Symptoms - Motors

Motors are extremely tolerant of sags and swells. Unless the RMS magnitudes are either very low or very high, motors typically have little response to these voltage variations. Keep in mind that if the motors are controlled by electronic drive controllers, the discussion on electronic equipment applies.

If the magnitudes are extreme, or if these disturbances occur frequently, then several symptoms may develop. First, extreme swells will electrically stress the windings on the stator. This leads to premature motor failure.

Second, extreme sags may cause the motor to lose enough rotational inertia to affect its performance or task. Third and last, if sags happen frequently enough, the motor may draw high inrush currents often enough to trip a breaker.