The Three-Phase Circuit Breaker is a three-pole magnetic control circuit device that provides the following functions:

Disconnect Switch: It provides a means whereby the conductors of a circuit can be isolated from their source of power. A single toggle handle operates all three poles. When used in this manner it is also called a safety or isolating switch.

Circuit Protector: It provides reliable circuit overload protection. The structure consists of three single poles, each rated at 5 A, assembled with an internal mechanical interlock which actuates all units simultaneously, opening each line conductor. The single toggle handle moves to the off position on overload, and cannot be forced to close until the overload is removed. It is said to be "trip-free".

Manual Control Switch: Its special time-delay series tripping characteristics, and high rupturing current capacity, make it useful as a direct motor on-off control switch, when used within its ratings. It may also be called a motor-circuit switch.