Mode Of Operation - Siemens 7KG6000-8AA Operating Instructions Manual

1.5 Mode of operation

The measuring signals, voltages and currents, are converted into
digital signals. From the values recorded, a microprocessor
calculates up to 15 derived values. The effective scan rate is 96
times the frequency of the measuring signal. This guarantees
correct results not only for sinusoid curves but also for distorted
waveforms.
The rms-values are the squared mean values of the sampling
values over three periods each.
The active power is the mean value obtained from the
multiplication of the current and voltage values. To determine the
reactive power, a frequency-independent phase angle of 90°
between voltage and current is provided internally. The apparent
power results from the summation of current and voltage
multiplications.
The power factor and phase angle between current and voltage are
calculated from the active and reactive power values. The
frequency is calculated from the duration of three system periods
each and filtered in order to avoid the influence of sudden phase
changes. The device determines the frequency by the voltage of
U1. For measuring the frequency, a minimum voltage of 30% of
the nominal value of the voltage is required.
The analog outputs are electrically isolated and carry load-
independent current or, optionally, internally configured load-
independent voltage.
E50417-K109U-C322-A SIMEAS 9
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