ABB RED650 Technical Manual page 534

Section 15
Monitoring
528
= × + - ×
X k X (1 k ) X
Old
EQUATION1407 V1 EN-US
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
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, it is possible for the end user to set the amplitudeIGenZeroDb level for
current and voltage measurement UGenZeroDb is forced to zero. When either
current or voltage measurement is forced to zero automatically the measured values
for power (P, Q and S) and power factor are forced to zero as well. Since the
measurement supervision functionality, included in CVMMXN, 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 "Measurement supervision").
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
If CT earthing parameter is set as described in section
reactive power will be always measured towards the protected object. This is
shown in the following figure 264.
Calculated
1MRK 505 394-UEN A
"Analog inputs", active and
Line differential protection RED650 2.2 IEC
Technical manual
(Equation 77)
SEMOD54417-250 v5
SEMOD54417-253 v5
SEMOD54417-256 v7