ABSTRACT
Harmonics cause distortions of the voltage and current waveforms, which have adverse effects on electrical equipment. Harmonics are one of the major power quality concerns. All triplen harmonics generated by nonlinear loads are zero sequence phasors. These add up in the neutral. In a three-phase four-wire system, with perfectly balanced single-phase loads between the phase and the neutral, all positive and negative sequence harmonics will cancel out, leaving only the zero sequence harmonics. Nonlinear loads are continually on the increase. It is estimated that, during the next 10 years, 60" of the loads on utility systems will be nonlinear. Harmonics in transformers originate as a result of saturation, switching, high-flux densities, and winding connections. The armature windings of a machine consist of phase coils that span approximately a pole pitch. Tooth ripples in electrical machinery are produced by slotting as these affect air-gap permeance. Generator neutrals have predominant third harmonic voltages.
