The problem of circuit breaking becomes complicated when voltages and currents in the range of kilovolt and kiloampere are involved. Circuit breaker (CB) is used in performing switching operations, and is a switch that can open live circuits. Circuit breakers are especially important in protective schemes where they have to interrupt fault currents, and isolate faulty section of the network. When the circuit breaker opens under fault condition many thousands of amperes pass through the contacts and the extinction of the arc and hence effective opening of the contacts of the CB are major engineering problems. When a circuit breaker opens, a high-frequency voltage, superimposed on the normal system voltage appears across the CB contacts. This voltage is known as transient recovery voltage (TRV) or restriking voltage, constituting a switching surge. Restriking delays arc quenching, and so it is detrimental to the circuit breaker as well as the entire system, since fault clearing may be delayed. This paper shows how resistance switching can be used to damp this surge and enable the CB to open before the magnitude of the voltage across the CB contacts reaches peak level, to prevent possible restriking of the arc.

Keywords : circuit breaker, arc, transient recovery voltage, restriking, resistance switching