ABB RELION 670 Series Technical Manual page 1043

1MRK 502 066-UUS B
Calibration of analog inputs
Measured currents and voltages used in the CVMMXN function can be calibrated to get class 0.5
measuring accuracy. This is achieved by magnitude 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 539.
IMagComp5
IMagComp30
IMagComp100
Degrees
IAngComp30
IAngComp5
IAngComp100
ANSI05000652 V3 EN-US
Figure 539: Calibration curves
The first current and voltage phase in the group signals will be used as reference and the
magnitude and angle compensation will be used for 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, V, 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:
Technical manual
Magnitude
% of In
compensation
+10
5
-10
Angle
compensation
+10
5
-10
30
0-5%: Constant
5-30-100%: Linear
>100%: Constant
30
Monitoring
SEMOD54417-293 v4
Measured
current
100
% of In
Measured
current
100
% of In
ANSI05000652_3_en.vsd
SEMOD54417-233 v3
Section 16
1037