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Description of Unit
Summation channels
Power factor cosφ
Phase voltages
Phase currents
Neutral current
Network frequency
Phase angles
D000030110 d – E650 Series 3 (ZMD400AT/CT, ZFD400AT/CT) – User Manual
Harmonics considered for reactive energy
As RMS values are used for the calculation of the apparent energy with cal-
culation method 2, not only the fundamental wave but also the harmonics
are taken into account. Therefore, if harmonics are present, the measured
values are greater than those of calculation method 1.
The values of two measurement quantities (incl. pulse inputs EX1 and EX2)
can be added. The added quantities must be of the same energy type
(active, reactive or apparent). The sum is stored in a total energy register.
The power factor cosφ is calculated in combimeters as follows:
The meter uses the method of calculation employed for calculating the
apparent power.
The rms values of the voltages U1
the mean values of the squares of the voltages by extracting the root and
directly from these the phase voltages U1, U2 and U3.
The rms values of the currents I1
mean values of the squares of the currents by extracting the root and di-
rectly from these the phase currents I1, I2 and I3.
The signal processor calculates the instantaneous neutral current i0 by
adding the instantaneous phase currents i1, i2 and i3.
Fig. 1.14
Neutral current I
The signal processor calculates the network frequency f
reciprocal from the time t
The signal processor calculates the phase angles between voltages U1-U2
and U1-U3 from the times t
the various voltages.
The signal processor calculates the phase angle between voltage U1 and
current per phase from the times t
sages of the voltage U1 and the phase currents.
2 forms of representation are available for displaying the phase angle.
These can be selected by parameterisation.
Case 1: All voltage and current angles are displayed clockwise with refer-
ence to the voltage in phase 1. The values of the angles are always posi-
tive and can be from 0 to 360°.
, U2
and U3
rms
rms
, I2
and I3
rms
rms
0
between two zero passages of voltage U1.
U1-U1
, t
and t
U1-U1
U1-U2
U1-U3
, t
and t
U1-I1
U1-I2
are obtained from
rms
are obtained from the
rms
by forming the
n
between zero passages of
between zero pas-
U1-I3
© Landis+Gyr AG
19/93
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