The maximum current that a moulded case circuit breaker can disconnect at rated voltage. Also known as rated short-circuit breaking current, its maximum breaking capacity corresponds to rated limit short-circuit breaking current.

The rated current in of circuit breaker refers to the current that the tripper can pass for a long time, that is, the rated current of the tripper. For circuit breakers with adjustable trippers, the maximum current that the trippers can pass for a long time.

The breaking capacity of a circuit breaker refers to the ability of the circuit breaker to safely cut off the fault current. It can be divided into limit breaking capacity Icu and operation breaking capacity Ics. Now Icu = Ics is 100% before Ics is less than Icu.