Power factor, harmonic distortion; causes, effects and considerations

Power factor has increasingly become a topic of discussion when specifying loads and AC/DC or AC/AC power sources. The European community has proposed standards for limiting the mains current distortion caused by nonlinear loads. A brief overview of emerging standards is provided. The definition of power factor and the difference between displacement and distortion power factor are explained. The effects of low power factor are discussed, with emphasis on nonlinear loads such as switch mode rectifiers. A basic explanation of total harmonic distortion (THD) is provided along with a discussion of sources of current distortion, the effects on power distribution equipment, heating effects on transformers and the effects on other loads connected to the network. The relationship between power factor and harmonic distortion is discussed. Harmonic distortion is the parameter best representing a figure of merit in defining power line and load quality for nonlinear loads