Molded Case Circuit Breakers MM1 series (hereinafter called as MM1 MCCB) is a new designed MCCB developed and manufactured adopting international advanced technology. MM1 MCCB rated insulating voltage AC 800V is suitable for using in the circuit of AC 50Hz /60Hz, rated voltage up to 690V, rated working current up to 630A to distribute electric power and to protect the line and the equipment from being damaged due to overload, short current and under-voltage. It can also be used for infrequently switch and starting of motor and for motor overload, short circuit and under-voltage protections. MM1 MCCB with the advantages of the small volume, high breaking capacity, short over-arcing (some of specification is zero arcing), strong anti-vibration and so on. In accordance with the ultimate short circuit breaking capacity classified into four types: Type C (basic), Type L (standard), Type M (middle), Type H (high).