The ideal alternating current (ac) waveform has two important features: (1) it contains no harmonic component besides the fundamental frequency (50 or 60 Hz), and (2) its magnitude is constant over a long period. Figure 13.1 shows the shape of an ideal waveform that is symmetrical and cyclic with constant period. A deviation from any of these characteristics results in what is known as power quality problem.
Unfortunately, the ideal waveform in Figure 13.1 does not exist in the real world. The nonlinear characteristics of most power equipment and the switching of loads tend to distort ...