Harmonics

Harmonics in electrical systems refer to voltage or current waveform distortions at frequencies that are integer multiples of the fundamental supply frequency. These distortions degrade power quality, causing excessive heating, torque pulsations, and premature failure in assets like motors and drives, particularly in industrial environments with non-linear loads such as variable frequency drives.

On the shop floor, harmonics are critical for maintenance reliability. In CMMS, when motors or VFDs fail with symptoms like overheating or bearing wear despite proper lubrication, reliability engineers analyze power quality data to identify harmonic distortion as the root cause, linking it to non-linear loads in work orders. Vibration analysis using FFT detects harmonic frequency peaks to distinguish faults like electrical unbalance from mechanical issues. Predictive maintenance systems continuously monitor Total Harmonic Distortion (THD) via IoT sensors; if THD exceeds thresholds (often >5%), work orders are automatically generated to install filters or inspect the distribution network, preventing equipment damage before it occurs.

• ⚠️Rotor bar and bearing pitting (electrical fluting) from harmonic currents inducing rotor harmonics, causing circulating currents that erode bearings and crack rotor bars, leading to catastrophic motor failure.
• ⚠️Insulation degradation and partial discharge misinterpretation, where harmonic stress alters PD patterns, leading to underestimated remaining life and unexpected cable explosions if not accounted for.
• ⚠️Inefficient preventive scheduling (over-maintenance) by relying solely on fixed-time lubrication or replacement without checking for electrical harmonics, causing repeated failures despite fresh parts due to unresolved root cause.