ABB RET650 Technical Manual page 441

1MRK 504 135-UEN A
Technical manual
IEC05000652 V2 EN
Figure 195: Calibration curves
The first current and voltage phase in the group signals will be used as reference and
the amplitude 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, 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:
= × + - ×
X k X (1 k ) X
Old
EQUATION1407 V1 EN
where:
X is a new measured value (that is P, Q, S, U, I or PF) to be given out from the function
X is the measured value given from the measurement function in previous execution cycle
Old
X is the new calculated value in the present execution cycle
Calculated
k is settable parameter by the end user which influence the filter properties
Calculated
Section 14
Monitoring
(Equation 107)
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