Basic Datas of Harmonics and VFD Harmonic Distortion Harmonic Distortin is a measure of the amount of deviation from a pure sinusoidal wave form that can be caused by a non-linear load (a VFD is considered a non-linear load because it only draws current from the power line as required). Distorted Waveform Distorted Waveform = fundamental (50Hz sinusoidal waveform) + multiples of the fundamental fr...