Applied in power distribution network with 50/60Hz AC while the rated operational voltage is 690V and the rated operational current is 6300A or below, the breaker is used for power distribution and protection of the circuit and electrical power units against overload, under voltage, short circuit and one-phase-to-ground fault. The breaker is equipped with smart protection functions, can achieve selective and accurate protection so as to improve the reliability of the power supply and avoid unnecessary black out. The breaker can be widely applied in power plants, factories, mines (especially using 690V) and modern high-rise buildings, especially in the power distribution system for intelligent buildings. It is also widely applied in green energy project such as wind power and solar power generation.