Harmonics (electrical power)

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In an electric power system, a harmonic of a voltage or current waveform is a sinusoidal wave whose frequency is an integer multiple of the fundamental frequency. Harmonic frequencies are produced by the action of non-linear loads such as rectifiers, discharge lighting, or saturated electric machines. They are a frequent cause of power quality problems and can result in increased equipment and conductor heating, misfiring in variable speed drives, and torque pulsations in motors and generators. Many non-linear electrical loads draw current only during portions of each AC cycle, producing a periodic but non-sinusoidal current waveform. If the waveform is periodic, it can be represented by a Fourier series as the sum of the fundamental frequency and harmonic components at integer multiples of the fundamental frequency. Harmonics are usually classified by two different criteria: the type of signal (voltage or current), and the order of the harmonic (even, odd, triplen, or non-triplen odd...

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