Solution: The device detect the fault and initiate the operation of the circuit breaker to isolate the defective element from the power system. Types: 1. Directional relay i.Induction type over current relay ii.Induction type reverse power relay 2. Differential relay 3. Distance relay (Based on transmission line distance) i.Impedance relay ii.Reactance relay iii.Admittance relay
Solution: During the current chopping a very high voltage may appear across circuit breaker contact.These voltage may danger the operation of the system.To reduce these voltage a shunt resistor across the circuit are used. This resistor depends on operation of circuit breaker and it's performed to reduce the RRRV(Rate of Rise of Restriking Voltage),Reduce the transient voltage (Maximum voltage at short period).. R = 0.5 √(L/C)
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