Calculate Stabilizing Resistor

You should take relay setting current. Supposing your CT secondary current is 5 amps and setting value is say 10 %, then you should take 0.5 Amps.

If the CT secondary is 1 amps and setting value is say 40 %, then you should take o.4 amps.

Hope this is clear.

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dear sir,

Can u tell that why stabilising resistor to be used in protection relays. is it for voltage drop?

Your understanding is grossly incorrect. You may please note that a stabilising resistor is added to an REF Relay circuit, to prevent a mal-operation of the relay for an external earth fault, in case one of the CTs involved in the fault saturates. Under such a condition, the saturated CT would act as a short circuit and would not pump any compensating current to the relay. Whereas, the unsaturated CT in the fault circuit would develop a voltage proportional to the fault current and the design Knee Point Voltage of the CT. This voltage developed by the CT shall not circulate a current so as to operate the relay.

So, the value of the stabilising resistor shall be: {R (total) - R (relay at the setting)}

R (total) = Relay operating voltage at the actual fault current / Relay set current

R (relay) = {VA Burden of the relay at the setting made / (set current)2}