In present disclosure, a movable bar guide portion is formed to protrude toward a movable bar in a shaft having a movable bar, and when a fault current is applied and the movable bar is rotated due to electromagnetic repulsion force, the movable bar and the movable bar guide portion contact each other, and thus, when the movable bar is rotated through the movable guide portion, movement of a rotation center of the movable bar is minimized.