1745
Users Manual
36
Unbalance
The ratio of negative-to-positive-sequence harmonics is calculated with the
angles and magnitudes of the phase voltages taken into account. These values
are averaged over the interval length defined in PQ Log.
Frequency
The line power frequency is measured and averaged over 10 seconds and the
resulting values are divided into 42 classes for establishing statistics. Values
are also averaged over the interval length defined in PQ Log.
Current Logging
The maximum values of the currents (L1 or A, L2 or B, L3 or C and N) are
measured, and the interval value of the current is calculated using the mean
value over the RMS values of the interval defined in PQ Log.
Logging Function A
If a 3-phase current sensor is connected, the neutral current is calculated on a
sample basis from the phase currents. If a 3-phase+N sensor is detected, you
can select between logging and calculating the neutral current in PQ Log.
Ipeak
The peak values of the current (samples, not RMS values) are averaged in the
PQ Log software over the predefined measuring interval.
Note
Short peak values do not contribute much to the average value and so I
max
can
be higher than I
peak
.
Crest Factor (CF)
The crest factor (CF) of the currents (L1 or A, L2 or B, L3 or C, and N) is the
ratio of current peak value divided by current RMS value, and is averaged over
the interval length defined in PQ Log. For sinusoidal signals, CF = 1.41, and
for square waves, CF =1.00
Summary of Contents for 1745
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