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The distortion power factor is used in power electronics to describe how a load’s harmonic distortion of the current decreases the average power transferred to the load. Distortion power factor is an important factor in the calculation of true power factor, which describes the decrease in average power transferred due to harmonics and to phase shift between voltage and current.

<math>

\mbox{distortion power factor} = {1 \over \sqrt{ 1 + \mbox{THD}_i^2}} = {I_{\mbox{1,rms}} \over I_{\mbox{rms}}}
</math>

<math>\mbox{THD}_i</math> is the total harmonic distortion of the load current. This definition assumes that the voltage stay undistorted (sinusoidal, without harmonics). This simplification is often a good approximation in practice. <math>I_{1,\mbox{rms}}</math> is the fundamental component of the current and <math>I_{\mbox{rms}}</math> is the total current - both are root mean square-values.

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

<math>

\mbox{PF} = \mbox{DPF} {I_{\mbox{1,rms}} \over I_{\mbox{rms}}}
</math>

See also

• Power factor

External links

• Harmonics and how they relate to power factor
• Power and RMS Values of Fourier Series