KCW2 series circuit breaker (hereinafter referred to as breaker) is mainly applied to the rated current of 630A to 4000A, rated voltage of AC 400V, 50Hz power distribution networks used to distribute electric power, protection circuit and power equipment to avoid received contained, under voltage, short circuit, single phase to ground fault and other hazards. Under normal conditions, but also as a line is not used frequently change. The circuit breaker protection with precise selectivity performance, improve power system security, continuity and reliability, to avoid unnecessary power outages. Products meet the standards of GB 14048.2 and IEC 60947-2.