A recent measurement indicates that harmonic distortion is above acceptable limits.
Harmonic distortion, an indicator of power quality, affects every motor operational parameter including torque, operating temperature, and vibration. High harmonic distortions increase rotor bar resistance, causing the top edges of rotor laminations to magnetically saturate, decreasing the rotor’s reactance. This decrease in rotor reactance increases the motor’s current draw, reduces its ability to produce torque, decreases its efficiency, and leads to excessive heating. Prolonged operation at high harmonic distortion can lead to motor failure. Therefore, NEMA recommends derating motors operating where harmonic distortion exceeds 4%.