What causes harmonic problems?
All electronic loads generate positive- and negative-sequence harmonic currents. Single-phase electronic loads, connected phase-neutral in a three-phase, four-wire distribution system, also generate zero-sequence harmonic currents. Three-phase motor drives and single-phase lighting loads often account for a significant portion of a systems 480V loads. Single-phase electronic office and data processing equipment typically accounts for more than 95% of a 120/208V power panels loads. At these levels, 100% Total Harmonic Distortion of Current is common.
