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Star point of a CT is a fixed installed point (Toward Bus or Towared Line) power flow does not affect the Star point of the CT
In case of3 O/C,2 O/C &1 Earth fault, REF, Standby Earth Fault, or in case of NPS Protection We take All3 Phase Strating END/ Finishing End /Both the End(REF) in Star, to get normal Current flow in the Relay & Excessive Current flow in Fault Condition
As we know CT Current will flow in Opposite direction of Power Flow.So it will not effect the Star point OF CT( CT Srar allways Grounded), But the change of Direction of Power Flow defenetely will going to affect in Case of Diection Relay.
2nd:- Suppose Power flow is from P1 to P2. that time connected Energymeter will show the added parameter like KWH,KVA,KVAR etc. But if Power flow reverses energymeter will not add, because all the CT current will come to STAR poiunt of CT & will become Zero.
In case of Differential Relay Power flow will trip the relay by adding I1 + I2 = some value more than Trip Set Value/ Bias value ( Basically in case of Zone Fault )
star point will still be neutral or at least unchanged. But you will get a reversed phase sequence. That what will happen in case of reversal of power flow, only.
