ABB REG650 Technical Manual page 504

Section 14
Monitoring
498
Default value for parameter k is 0.00. With this value the new calculated value is
immediately given out without any filtering (that is, without any additional delay).
When k is set to value bigger than 0, the filtering is enabled. Appropriate value of k
shall be determined separately for every application. Some typical value for k =0.14.
Zero point clamping
In order to avoid erroneous measurements when either current or voltage signal is not
present, the amplitude level for current and voltage measurement is forced to zero.
When either current or voltage measurement is forced to zero automatically the
measured values for power (P, Q & S) and power factor are forced to zero as well.
Since the measurement supervision functionality, included in the CVMMXN
function, is using these values the zero clamping will influence the subsequent
supervision (observe the possibility to do zero point clamping within measurement
supervision, see section
Compensation facility
In order to compensate for small amplitude and angular errors in the complete
measurement chain (CT error, VT error, IED input transformer errors and so on.) it is
possible to perform on site calibration of the power measurement. This is achieved by
setting the complex constant which is then internally used within the function to
multiply the calculated complex apparent power S. This constant is set as amplitude
(setting parameter PowAmpFact, default value 1.000) and angle (setting parameter
PowAngComp, default value 0.0 degrees). Default values for these two parameters are
done in such way that they do not influence internally calculated value (complex
constant has default value 1). In this way calibration, for specific operating range (for
example, around rated power) can be done at site. However, to perform this calibration
it is necessary to have an external power meter with high accuracy class available.
Directionality
CTStartPoint defines if the CTs earthing point is located towards or from the protected
object under observation. If everything is properly set power is always measured
towards protection object.
"Measurement supervision").
1MRK 502 048-UEN A
Technical manual