chapter  10
9 Pages

Power Factor Correction

WithJoseph E. Fleckenstein

A charge imposed by a utility on a customer for a power factor below a preferred value seems entirely warranted. Low power factors necessitate greater capital expenses by the utility. Low power factors can be caused by a number of electrical energy-consuming devices including fluorescent lighting, transformers, arc furnaces, welding equipment, and induction motors. In those installations with a lagging power factor, corrections can be made by the use of capacitors wired in parallel with the load. Since motors are the most common source of a lagging power factor, it would be natural to consider the installation of capacitors near each motor and to wire the capacitors in parallel with the motor. Switching of capacitors on and off with contacts that are of an electromechanical design can generate voltage spikes that can be a source of difficulties. Designs that use thyristors to provide "zero switching" have proved to be especially beneficial in eliminating this source of voltage spikes.