Abstract: A molded case circuit breaker includes a movable upper electrical contact having a base portion formed at one longitudinal end thereof with an elongated stop pin fixedly secured thereto and outwardly projecting therefrom for engaging one or more elongated upper spring arms of one or more torsion springs. A lower spring arm of each torsion spring is disposed in contact with a cross bar of an operating mechanism of the circuit breaker. During normal operation, the stop pin loads the upper spring arm with a force at a distance relatively close to the fulcrum of each torsion spring to cause the movement of the upper electrical contact in unison with the cross bar.

Abstract: A molded case circuit breaker includes a movable lower electrical contact having a formed stationary member, a movable contact arm, a pair of electrical contact compression springs, a contact arm compression spring and a contact secured to the upper end of the movable contact arm for physically and electrically contacting a separable upper electrical contact. An integral longitudinal end portion of the stationary member extends through the base of the cirucit breaker to form an external terminal of the circuit breaker. The opposite longitudinal end of the stationary member is curved for receiving a rotatable pin fixedly secured to the movable contact arm for rotation therewith. The rotatable pin is biased by the pair of compression springs into effective current conducting contact with the curved end of the stationary member. The contact arm compression spring contacts the underside of the movable contact arm to bias the contact secured thereto into engagement with the upper electrical contact.

Abstract: A molded case circuit breaker includes a single coil solenoid operator for placing the handle of the circuit breaker in its ON position or in its OFF position. The solenoid operator includes a single coil solenoid formed by an electromagnet secured to a movable electromagnet drive plate and by an armature secured to a movable armature drive plate. The drive plates are disposed for rectilinear movement and are configured alternately to engage a formed trigger plate secured to the handle to move the trigger plate and the handle between the ON position and the OFF position of the handle. A pair of pivotable, bistable mechanical latches are configured to engage and stop further movement of alternate drive plates depending upon the state of the latches. Successive actuations of the single coil solenoid operator cause the handle to be placed alternately in its ON position or in its OFF position.

Abstract: A molded case circuit breaker includes a movable upper electrical contact having a base portion with a slot formed therein for releasably receiving a portion of an elongated spring biased locking pin disposed in a rotatable cross bar of an operating mechanism of the circuit breaker. The locking pin is biased in the slot by a pair of tension springs secured to the cross bar, enabling the upper electrical contact to move in unison with the cross bar. Upon the occurrence of a high level short circuit or fault current of sufficient magnitude, the pin is displaced from the slot enabling the independent rotational movement of the upper contact arm. During such movement, an elongated leaf spring is downwardly deflected and then released by the base portion. Subsequently, the upper electrical contact is prevented from contacting the lower electrical contact by the engagement of the leaf spring with the base portion.

Abstract: A molded case circuit breaker includes a highly integrated operating mechanism having an over-center toggle mechanism for opening and closing a pair of electrical contacts and a trip mechanism for responding to overload and short circuit or fault current conditions to separate the pair of electrical contacts. A generally flat, intermediate latch plate includes an upper latch surface for latching with a movable cradle of the over-center toggle mechanism and a lower latch surface for latching with a trip bar of the trip mechanism and a pair of outwardly projecting pivot arms disposed between the upper and lower latch surfaces. The over-center toggle mechanism includes a pair of upper toggle links and a pair of lower toggle links interconnected by a toggle spring pin.