Investigation of the Breaking Capacity of the Automatic Circuit-Breakers in the Short-Circuit Mode

Resumo

Arc-quenching processes in automatic ac circuit breakers with a deionic lattice are considered. It is noted that the arc-quenching system of the circuit-breaker should be functional upon switching of the short-circuit currents, which can exceed 100 kA, and currents from the nominal to critical values of several tens of amperes. One of the main parameters of the arc-quenching system is the number of plates of the arc-quenching lattice, which determines the dimension and the braking capacity of the circuit breaker. The calculation method for the number of gaps ensuring the reliable arc-quenching was proposed. The most optimum design of the arc chute was revealed. Performance of the circuit breakers should be confirmed by the direct switching tests; however, due to the large switching power of the disconnected circuit that is provided for in the regulatory and technical documentation, it is recommended to monitor the operation of the circuit breakers based on the results of preliminary tests in a synthetic circuit.