WAGO-I/O-SYSTEM 750
Function Description
39
750-494 3-Phase Power Measurement Module
Manual
Version 1.2.0
frequency and current are no longer possible. The measuring accuracy of all
current-depending variables (current, power, energy) falls off by 0.4%.
3.
Near the ZC limit, the accuracy of the phase angle measurement decreases
to a value of ± 1.5 °.
4.
If a current measuring input operates near no-load, higher measuring errors
can occur for this measuring path.
5.
Measuring errors due to input overdrive:
When the input current or input voltage exceeds the nominal values for the
I/O module, input overdrive is produced (see figure below). The I/O module
cannot digitize these values and limits the measured values to the maximum
measurable range (clipping of the current or voltage measured values). As a
result, the RMS value that is output is erroneous. The more the input is
overdriven (and, thus, the reference points for RMS calculation), the greater
the measuring error.
Clipping of the voltage or current values is displayed via the expanded
status word 1 in the process image and by LED C (current) or LED G
(voltage) in diagnostics.
Figure 10: Input Overdrive (Clipping)
For
DC measurements
, the error is <= 1% of the full-scale value for current,
voltage and power.
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