Monthly Archives: March 2014

Power Factor Capacitors and Harmonic Filters – Application Considerations

(source : Eaton Sheet 35007 sept 2011)

Harmonic Considerations

A discussion of power system harmonics is incomplete without discussing the effects of power factor correction capacitors. In an industrial plant containing power factor correction capacitors, harmonic currents and voltages can be magnified considerably due to the interaction of the capacitors with the service transformer. This is referred to as harmonic resonance or parallel resonance. For a typical plant containing power factor correction capacitors, the resonant frequency (frequency at which amplification occurs) normally falls in the vicinity of the 5th to the 13th harmonic. Because nonlinear loads typically inject currents at the 5th, 7th, 11th and 13th harmonics, a resonant or near-resonant condition will often result if drives and capacitors are installed on the same system, producing the symptoms and problems with blown fuses, damaged capacitors or failures in other portions of the electrical distribution system. Continue reading

Electric Power Quality and Lighting (part 2)

Posted May 29 2012 by Sufi Shah Hamid Jalali in Energy Efficiency, Lighting on Electrical Engineering Portal

Original Source: Wolsey, Robert, Power Quality, Volume 2, Number 2, February 1995 (Lighting Research Center (LRC) and Power Quality),

What is power factor?

Power factor is a measure of how effectively a device converts input current and voltage into useful electric power. Mathematically it is defined as follows:power-factor-triangle-explained

Power factor triangle




Where P is active power and S is the apparent power.

It is often confused with: Continue reading