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The harmonic analyzer uses the Fast Fourier Transform (FFT) algorithm which runs twice a second on
the selected channel.
The sample memory is of 1024 samples length and 13 bits resolution with a sampling rate of 4096Hz.
According to theory, a periodic signal may have only odd multiples of the main frequency. Thus, in a 50Hz
network, harmonics will be found only at 150, 250, 350, 450Hz etc...
The unit is able to analyze up to 1800Hz and up to the 31
st
harmonic, whichever is smaller. Thus, in a
50Hz system all 31 harmonics will be displayed, but on a 60Hz system only 29 harmonics will be shown
on screen.
Graphical Harmonic Table
Alphanumeric Harmonics Table
Harmonics are represented by 2 different methods on the device display. The first one is a graphical
representation allowing one sight perception of the harmonic structure. Because of the display resolution,
only harmonics above 2% are displayed.
The second method is alphanumeric; thus, all harmonics are displayed with 0.1% resolution in order to
provide more detailed information.
On RainbowPlus program, harmonics and waveform are displayed on a single screen with more
resolution.
RainbowPlus Scada section: Harmonic Analysis and Waveform Display
