D-500 MK2 User Manual Firmware V-6.3
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The harmonic analyzer consists on a Fast Fourier Transform (FFT) algorithm which run twice a second
on the selected channel.
The sample memory is of 1024 samples length and 13 bits resolution with a sampling rate of 4096 s/s.
The theory says that 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, 450 Hz etc...
The unit is able to analyze up to 1800Hz and up to 31th harmonic, whichever is smaller. Thus in a 50Hz
system all 31 harmonics will be displayed, but in a 60Hz system only 29 harmonics will come to the
screen.
In case of a 400Hz system, only the 3
rd
harmonic will be displayed.
Graphical Harmonic Table
Alphanumeric Harmonics Table
Harmonic are represented by 2 different ways 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 on the B&W display models.
The second display 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
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