The release of moulded case circuit breaker is divided into instantaneous release and overload release. Instantaneous and overload trippers are synthesized into compound trippers, which do not contain dividing trippers, instantaneous and overload trippers are inside the moulded case circuit breaker, while dividing excitation is usually an accessory added to the moulded case circuit breaker. The dividing excitation trippers are the trippers of the electric circuit breaker, which provide power supply for dividing excitation with external power supply, mainly for remote use. Cheng breaks the circuit breaker.

Instantaneous tripping is a short circuit tripping device, usually 5-10 times (C-type tripping) and 10-15 times (D-type tripping) of rated current tripping, overload tripping device is generally not tripped within 1 hour under 1.13 times rated current, 1.45 times rated current within 1 hour, which is the standard of circuit breaker under 40 degrees constant temperature.

The instantaneous tripper with rated current of 10-15 times (D-type tripping) is usually used in motor distribution, while the circuit breaker with rated current of 5-10 times (C-type tripping) is usually used in general distribution.

Distribution trippers mainly depend on whether they need to be operated remotely. In addition, they can only be operated remotely. If they need to be closed remotely, they need an electric operation mechanism.

Breakers are divided into B, C and D types according to the release mode, which means the release characteristic curve (current-release time) of circuit breakers. Characteristic B is suitable for pure resistive load and low inductance lighting circuit, Characteristic C is suitable for inductive load and high inductance lighting circuit, Characteristic D is suitable for distribution system with high inductance load and large impulse current.