ABB Relion 650 Series Technical Manual page 387

1MRK 511 424-UEN B
Bay control REC650 2.2 IEC
Technical manual
Calibration of analog inputs
Measured currents and voltages used in the CVMMXN function can be calibrated
to get 0.5 class measuring accuracy. This is achieved by amplitude and angle
compensation at 5, 30 and 100% of rated current and voltage. The compensation
below 5% and above 100% is constant and linear in between, see example in
figure 182.
IEC05000652 V2 EN-US
Figure 182: Calibration curves
The first current and voltage phase signal, in the group signals will be used as
reference. The amplitude and angle compensation will be used for other related
input signals.
Low pass filtering
In order to minimize the influence of the noise signal on the measurement it is
possible to introduce the recursive, low pass filtering of the measured values for P,
Q, S, U, I and power factor. This will make slower measurement response to the
step changes in the measured quantity. Filtering is performed in accordance with
the following recursive formula:
Section 10
Monitoring
SEMOD54417-293 v5
SEMOD54417-233 v4
381