What will happen if we use Metering core of CT for Protection Relay?
Answer:
We cannot use Metering Core of CT for Protection Relay, because if we do, the Protection Relay will not operate during Fault.
The main function of the Metering core of the CT is to carry full load current.
It is designed in such a way, that it has a low Saturation Level and gets saturated during the Faults (When there is a flow of very high current through it).
And so if we use Metering Core of CT for Protection Relay, during the fault, it will get Saturated and once Saturated, it does not follow the Connected CT Ratio i.e it will not give correct reflection of Fault current and so the Relay will not operate, when there is fault.
