Phase Current Measurement Cmmxu - ABB Relion Technical Manual

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Directionality

CTStartPoint defines if the CTs grounding point is located towards or from the protected

object under observation. If everything is properly set power is always measured towards

protection object.

ANSI05000373 V2 EN

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 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.

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 magnitude and angle compensation at 5, 30 and 100%

ANSI05000373_2_en.vsd

1MRK 502 048-UUS A

Technical manual

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650 series Reg650 ansi