Electro Industries/GaugeTech
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Doc# E166703 1-14
1: Three-Phase Power Measurement
where is the angle between the voltage and the current (see Fig. 1.9).
In applications where the voltage and current are not distorted, the Total Power Fac-
tor will equal the Displacement Power Factor. But if harmonic distortion is present, the
two power factors will not be equal.
1.4: Harmonic Distortion
Harmonic distortion is primarily the result of high concentrations of non-linear loads.
Devices such as computer power supplies, variable speed drives and fluorescent light
ballasts make current demands that do not match the sinusoidal waveform of AC
electricity. As a result, the current waveform feeding these loads is periodic but not
sinusoidal. Figure 1.10 shows a normal, sinusoidal current waveform. This example
has no distortion.
Figure 1.10: Nondistorted Current Waveform
Figure 1.11 shows a current waveform with a slight amount of harmonic distortion.
The waveform is still periodic and is fluctuating at the normal 60 Hz frequency.
However, the waveform is not a smooth sinusoidal form as seen in Figure 1.10.
Time
Amps
– 1000
– 500
0
500
1000
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