MM3 series moulded case circuit breaker (hereinafter called MM3 MCCB) is a new designed MM3 MCCB developed and manufactured adopting advanced international technology. It has the advantages of compacting structure, small volume, and international high breaking capacity. The inner device is moulding installed, adopt the terminal protective cover to keep safe and the different colors of the basic board and covering board to increase the beauty. MM3 MCCB is applicable circuit of AC 50Hz/60Hz, rated insulation voltage 660V, rated operating voltage up to 250V (DC). The rated operating current is 12.5A-1250A, for distribute energy of electricity and infrequent making and breaking circuit, and infrequent starting of squirrel cage motor (rated operating current up to 400A) at normal condition with the function of the protection against overload and short circuit and under voltage. MM3 MCCB complies with standard of IEC 947-2, GB 14048.4 and so on.