BM-63GQ/2P series mini-circuit breakers with over-current, over-voltage and under-voltage protection (small cases) are suitable for ac 50Hz power supply lines with rated working voltage of 230V and rated current of 6-63a.When the line voltage is greater than 275V, less than 160V, the tripper makes the assembled tripping, protect the electrical equipment.It is characterized by small volume, accurate, stable and reliable detection line voltage.