ABB ret650, Technical Manual

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Busbar
Protected
Object
P Q
IEC09000038-1-en.vsd
IED
IEC09000038-1-EN V1 EN
Figure 196: Internal IED directionality convention for P & Q measurements
Practically, it means that active and reactive power will have positive values when
they flow from the busbar towards the protected object and they will have negative
values when they flow from the protected object towards the busbar.
In some application, for example, when power is measured on the secondary side of
the power transformer it might be desirable, from the end client point of view, to have
actually opposite directional convention for active and reactive power measurements.
This can be easily achieved by setting parameter
PowAngComp to value of 180.0
degrees. With such setting the active and reactive power will have positive values
when they flow from the protected object towards the busbar.
Frequency
Frequency is actually not calculated within measurement block. It is simply obtained
from the pre-processing block and then just given out from the measurement block as
an output.
14.1.8.3 Phase current measurement CMMXU
The Phase current measurement (CMMXU) function must be connected to three-
phase current input in the configuration tool to be operable. Currents handled in the
function can be calibrated to get better then class 0.5 measuring accuracy for internal
use, on the outputs and IEC 61850. This is achieved by amplitude and angle
1MRK 504 135-UEN A
Section 14
Monitoring
437
Technical manual