ABB ret650, Technical Manual

Page: 441 / 670

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:
(1 )
Old Calculated
X k X k X
= × + - ×
EQUATION1407 V1 EN
(Equation 107)
where:
X is a new measured value (that is P, Q, S, U, I or PF) to be given out from the function
X
Old
is the measured value given from the measurement function in previous execution cycle
X
Calculated
is the new calculated value in the present execution cycle
k is settable parameter by the end user which influence the filter properties
1MRK 504 135-UEN A
Section 14
Monitoring
435
Technical manual