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How does a MiCOM P63x relay calculate Idiff and Irestrain

The user would like to calculate the Idiff (differential current) and Ires (restrain current) given the injection currents and matching factors

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Micom P63x transformer differential relay

Calculating MiCOM settings

The formula below is used by the relay to calculate the Idiff and Irestrain:

To simplify the equations, assume that the Zero-sequence current filtering is disabled :

Where Kam,a and Kam,b are the amplitude matching factors calculated by the relay based on Iref/Inom on side a and side b, respectively. Refer to the differential protection section in the manual for more information.
I,a,sec = 10 A                     I,nom,secondary= 5 Amps             Kam,a= 2.76
I,b,sec = 5 A (180 deg)        Kam,b= 1.32

Iref is calculated based reference power and the nominal voltage on side a and b.
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