All harmonic parameters, except phase voltage and current harmonics, can be read
via the front panel. Either harmonic parameter can be accessed through
communications and used as a trigger for setpoint operation.
4.5.3 Real-time Waveform Capture
The real-time waveforms sampled at a rate of 128 samples per cycle that is used in
the instrument for harmonic measurements can be captured and transmitted via
communications to a master PC for more detailed harmonic analysis. Two
waveforms (voltage and current) for a single phase can be captured together at the
time of an incoming request, and will be held in the communications buffer until the
next request for waveform capture.
NOTES
1. For voltage waveforms, see NOTE 1 in the previous paragraph.
2. For a 3-wire connection, sampled waveforms may not be used for calculation of power
harmonics on separate phase.
Notice that high-resolution waveforms are not synchronized between different
phases, so you cannot use those for inter-phase harmonic measurements.
4.6 Auxiliary Measurements
4.6.1 Voltage and Current Unbalance
For both voltage and current, the PM295 provides calculation of the unbalance as
the largest deviation of the measured phase values expressed in percentage of the
phase average value. These are calculated as follows:
V V
Vavg
max min
×100%
where:
Vmax (Imax) - the greatest phase voltage (current)
Vmin (Imin) - the lowest phase voltage (current)
Vavg (Iavg) - average phase voltage (current)
Unbalance readings for voltage and current are accessible via the front panel,
communications, and can trigger setpoint operations.
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