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Calculation of THD in Measuring Function P
THD – Measuring Function P
Function P does not measure harmonic values.
THDV
Voltages:
V
: RMS value of total signal
RMS
V
: RMS value of the fundamental
1
THDI
Currents:
I
: RMS value of the total signal.
RMS
I
: RMS value of the fundamental.
1
THDI for currents < 5% of IE (measuring range) can have additional
uncertainties, or can be suppressed.
Harmonics up to 50th order are taken into account.
Flicker
Flicker is the visual impression of unsteadiness in a light source whose
luminance or spectral distribution changes over time. Flicker is logged in
accordance with the IEC 61000-4-15 standard. The short-term (st) flicker Pst
is logged over a default standard interval of 10 minutes, and is used to
calculate the long-term (lt) flicker Plt (by taking the sliding average of 12
short-term values). The interval value can be changed as needed in PQ Log.
2
2
V
V
RMS
1
V
1
2
2
I
I
RMS
1
I
1
Note
Power Quality Logger
Methods of Logging
t
35
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