The moulded case circuit breaker is designed for power distribution networks with AC50/60Hz, rated current 800A, rated work voltage 690V, and rated insulation voltage 690V.It is used to non-frequent making and breaking operation under normal condition for overload and short-circuit protection. The circuit breaker with rated frame class current less than and including 400A can be used in the squirrel cage type motor for non frequent starting, breaking in operation, and it also can provide overload, short-circuit and under-voltage protection for motor. The products comform to IEC 60947-2,IEC 60947-4 standard.