ABSTRACT
The practice of adding capacitors in parallel with a load in order to adjust the lagging power factor towards unity is termed power factor improvement, or power factor correction. Power-factor capacitors are usually oil-impregnated paper dielectric capacitors, with their plates enclosed in oil-filled metal tanks. These capacitors are always rated in reactive volt amperes, never in farads. Banks of capacitors enable individual capacitors to be brought on line, automatically or manually, to ensure optimum power factor improvement for variations in the load's reactive power. This chapter describes the terms, 'power factor', 'lagging' power factor and 'leading' power factor and explains why increasing a load's power factor towards unity will reduce the current supplied to that load. It outlines the main advantages of improving the power factor of a load and explores why a power factor capacitor is rated in reactive volt amperes, rather than in farads.
