Power Factor
Harmonic distortion: why VFDs and LEDs matter
6 min read · Updated 2026
Total Harmonic Distortion (THD) can derate motors and trip protection unexpectedly.
What causes THD
Non-linear loads — VFDs, LED drivers, UPS systems — inject harmonic currents onto the network.
Managing THD
Keep THD < 5% at PCC per IEEE 519. Add line reactors on VFDs and use harmonic filters for larger loads.
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