Total Harmonic Distortion (THD)

THD measures how much a driver’s input current deviates from a pure sine wave, expressed as a percentage of the fundamental. Switching power supplies naturally draw distorted current; good power-factor-correction circuitry keeps industrial LED drivers below 15–20% THD. Why it matters at scale: harmonic currents add in the neutral conductor of three-phase systems, heat transformers, and can trip sensitive protection or interfere with power-line-communication meters. Large lighting arrays — a warehouse with 400 high bays, a stadium with hundreds of flood heads — are precisely where THD specifications earn their place next to PF in the electrical schedule.