Harmonic spectrum: Difference between revisions
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== Principle == | |||
Each type of device causing harmonics draws a particular form of harmonic current (amplitude and phase displacement).<br>These values, notably the amplitude for each harmonic order, are essential for analysis. | Each type of device causing harmonics draws a particular form of harmonic current (amplitude and phase displacement).<br>These values, notably the amplitude for each harmonic order, are essential for analysis. | ||
== Individual harmonic distortion (or harmonic distortion of order h) == | |||
The individual harmonic distortion is defined as the percentage of harmonics for order h with respect to the fundamental.<br><math>U_h(%)=100 \frac{U_h}{U_1}</math> | The individual harmonic distortion is defined as the percentage of harmonics for order h with respect to the fundamental.<br><math>U_h(%)=100 \frac{U_h}{U_1}</math> | ||
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<math>i_h(%)=100 \frac {I_h}{I_1}</math> | <math>i_h(%)=100 \frac {I_h}{I_1}</math> | ||
== Harmonic spectrum == | |||
By representing the amplitude of each harmonic order with respect to its frequency, it is possible to obtain a graph called the harmonic spectrum.'''Figure M12 '''shows an example of the harmonic spectrum for a rectangular signal. | By representing the amplitude of each harmonic order with respect to its frequency, it is possible to obtain a graph called the harmonic spectrum.'''Figure M12 '''shows an example of the harmonic spectrum for a rectangular signal. | ||
== Rms value == | |||
The rms value of the voltage and current can be calculated as a function of the rms value of the various harmonic orders.<br><math>Irms=\sqrt {\sum_{h=1}^\infty I_h^2}</math> | The rms value of the voltage and current can be calculated as a function of the rms value of the various harmonic orders.<br><math>Irms=\sqrt {\sum_{h=1}^\infty I_h^2}</math> | ||
Revision as of 09:00, 16 June 2011
Principle
Each type of device causing harmonics draws a particular form of harmonic current (amplitude and phase displacement).
These values, notably the amplitude for each harmonic order, are essential for analysis.
Individual harmonic distortion (or harmonic distortion of order h)
The individual harmonic distortion is defined as the percentage of harmonics for order h with respect to the fundamental.
[math]\displaystyle{ U_h(%)=100 \frac{U_h}{U_1} }[/math]
or
[math]\displaystyle{ i_h(%)=100 \frac {I_h}{I_1} }[/math]
Harmonic spectrum
By representing the amplitude of each harmonic order with respect to its frequency, it is possible to obtain a graph called the harmonic spectrum.Figure M12 shows an example of the harmonic spectrum for a rectangular signal.
Rms value
The rms value of the voltage and current can be calculated as a function of the rms value of the various harmonic orders.
[math]\displaystyle{ Irms=\sqrt {\sum_{h=1}^\infty I_h^2} }[/math]
and
[math]\displaystyle{ Urms=\sqrt {\sum_{h=1}^\infty U_h^2} }[/math]
Fig. M12: Harmonic spectrum of a rectangular signal, for a voltage U (t)
