Operating mechanism of a molded case circuit breaker

An operating mechanism of a molded case low-voltage electrical circuit breaker, said circuit breaker comprising a handle and at least one movable contact, said operating mechanism controlling manual opening, manual closing and automatic opening of the circuit breaker, said operating mechanism comprising:

• a latch articulated on a fixed spindle and having a cam surface;
• a toggle comprising a first lever linked to the movable contact of the circuit breaker, and a second lever articulated on the latch via an articulation spindle, the first and second levers being joined to each other via a toggle spindle;
• a spring attached to the toggle spindle and to the handle;
• a lock designed to cooperate with said latch to hold said latch in a locked position;
• and
• a cam-follower roller actuated by the handle and designed to cooperate with the cam surface of the latch to move the latch to the locked position, said handle being able to move between (i) a closed position wherein the spring urges the toggle toward an extension position, (ii) a reset position wherein the spring urges the toggle to a broken position, the latch being in the locked position and the circuit breaker being open, and (iii) a tripped position wherein the latch is unlocked and the toggle is urged toward the broken position,
• wherein the cam surface comprises a slope change point between a first section corresponding appreciably to the travel of the handle between the tripped position and the reset position, and a second section corresponding to the reset position, the slope of the first section being such that the resultant of the forces derived from the spring and exerted on the handle urges the handle to the tripped position, the slope of the second section being such that the handle is urged to the reset position such that when the handle is in the reset position, the handle is maintained in the reset position upon unlocking of the latch via movement of the lock.