Patent ID: 6924720

Claim:
A circuit breaker comprising: a fixed contact, a movable contact movably arranged to the fixed contact, an operation handle moving between an ON position and an OFF position for opening and closing the movable contact, a switching device including a switching lever connected to the operation handle and having a protrusion, a toggle linkage connected to the movable contact and having a link shaft, and upper and lower links connected by the link shaft, a tripping mechanism for activating the toggle linkage in response to an over-current, and an operation spring disposed between the switching lever and the toggle linkage, an over-current tripping device connected to the switching device for performing a tripping operation in response to the over-current, and a locking member attached to the switching device for interconnecting the toggle linkage and the switching lever to restrict a movement range of the switching lever according to a position of the toggle linkage so that when the movable contact is stuck to the fixed contact, the locking member prevents the handle from moving to the OFF position by restraining a movement of the switching lever, said locking member being formed in a plate shape including an irregularly shaped slit fitted in the protrusion of the switching lever for restricting the movement range of the switching lever, and a stopper arm disposed adjacent to the link shaft of the toggle linkage, said locking member having a rear end pivotally supported on the switching device.