.: Distortion power factor

Tuesday, May 31, 2011

Distortion power factor

The distortion power factor describes how the harmonic distortion of a load current decreases the average power transferred to the load.

$\mbox{distortion power factor} = {1 \over \sqrt{ 1 + \mbox{THD}_i^2}} = {I_{\mbox{1,rms}} \over I_{\mbox{rms}}}$

$THD i$ is the total harmonic distortion of the load current. This definition assumes that the voltage stays undistorted (sinusoidal, without harmonics). This simplification is often a good approximation in practice. $I 1,rms$ is the fundamental component of the current and $I rms$ is the total current - both are root mean square-values.

The result when multiplied with the displacement power factor (DPF) is the overall, true power factor or just power factor (PF):

$\mbox{PF} = \mbox{DPF} {I_{\mbox{1,rms}} \over I_{\mbox{rms}}}$

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Tuesday, May 31, 2011

Distortion power factor

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