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Influence of voltage nonsinusoidality

Nonsinusoidal voltage - distortion of the sinusoidal form of the voltage curve.


  Electric receivers with a non-linear current-voltage characteristic consume a current whose shape of the curve differs from the sinusoidal one. And the flow of such a current through the elements of the electrical network creates a voltage drop on them, different from the sinusoidal, this is the cause of the distortion of the sinusoidal shape of the voltage curve.

For example, semiconductor converters consume a current of a trapezoidal shape, figuratively speaking - snatch from a sinusoid a piece of a rectangular shape.

35% of electricity is converted and consumed
on a constant voltage.

Sources of non-sinusoidal voltage are: static converters, arc steelmaking and induction furnaces, transformers, synchronous motors, welding installations, gas-discharge lighting and household appliances and so on.

Strictly speaking, all consumers, except for incandescent lamps have a nonlinear voltage-current characteristic.

Increase in underrecipitation of electric power, due to the inhibitory effect on the induction counters of harmonics of the reverse sequence.

The function describing the non-sinusoidal voltage curve can be decomposed into a Fourier series of sinusoidal (harmonic) components with a frequency of n times the frequency of the power supply network-the frequency of the first harmonic (f n = 1 = 50 Hz, f n = 2 = 100 Hz, f n = 3 = 150 Hz ...).

In connection with various features of generation, propagation through networks, and influence on the operation of equipment, there are even and odd harmonic components, as well as direct sequence components (1, 4, 7, etc.), reverse sequence (2, 5, 8 and etc.) and zero sequence (harmonics multiple of three).

With increasing frequency (harmonic component numbers), the harmonic amplitude decreases.