Abstract: A thermo magnetic trip unit is disclosed for a circuit breaker, in particular for a molded case circuit breaker. In an embodiment, the thermo magnetic trip unit includes a braid plate, a load plate and a heater arranged between the braid plate and the load plate, whereby the braid plate, the load plate and the heater form a current path. In an embodiment, the thermo magnetic trip unit further includes a bimetal positioned on the heater, a rotatable trip bar and an energy storage spring, whereby the trip bar can release the energy storage spring after being touched by the bimetal with certain power. Further, the bimetal is an arched or curved snap action bimetal which snaps over to an opposite direction as soon as a certain temperature is reached. Further, a circuit breaker, in particular molded case circuit breaker, including such thermo magnetic trip unit, is disclosed.

Abstract: A device can be installed inside a circuit breaker assembly to reduce friction between an armature and a cradle, which in turn, allows the circuit breaker to trip without requiring significant force. Such device can be a collapsible mechanism configured to swivel about its hinged connection to the armature.

Abstract: A thermal overload relay includes main bimetals which bend upon detection of an overload current; a release lever displaced via movement of a shifter moved in response to the bending of the main bimetals; and a contact reversing mechanism for changing-over contacts responsive to a rotation of the release lever. The main bimetals, the release lever and the contact reversing mechanism are all disposed in a case. The contact reversing mechanism includes a pivotable movable plate; a reversing spring reversing the movable plate by coupling with a rotated release lever; and an interlock plate rotating around a support shaft together with the movable plate. Each contact has a normally opened contact piece and a normally closed contact piece and is disposed respectively in the vicinity of a front surface and in the vicinity of a back surface of the interlock plate.

Abstract: A circuit breaker (10) has a current carrying bimetallic element (18) which bends upon self-heating and upon being subjected to a selected overload current transfers motion to a connecting plate (32) which displaces a latch surface (42b) from a catch (34a) of a bell crank mechanism (34) allowing a spring biased operating member (28) to move movable contact means (12) out of contact engagement with stationary contact means (14) thereby tripping the circuit breaker. An arc sensing circuit (52) is coupled to the load circuit and upon sensing selected arcs causes an arc responsive actuator (56, 62) to be energized to transfer motion to the latch (42) to trip the circuit breaker.

Abstract: An advanced circuit breaker system and method includes first and second terminals to electrically couple the advanced circuit breaker to an electrical circuit. A cam applies a first torque to a rotatable contact arm, having an arm contact electrically coupled to the first terminal, from a first position to a second position of the contact arm and a second torque to the contact arm from the second position to a third position. A bimetal blade, having a blade contact electrically coupled to the second terminal, changes shape when electrical current flowing through it exceeds a threshold for at least a predetermined amount of time. The arm contact maintains contact with the blade contact when the first torque occurs and separates from the blade contact when the second torque occurs. The blade contact changes shape to increase separation from the arm contact if electrical current exceeds at least a certain amount above the threshold.

Abstract: A circuit breaker includes main circuit contact shoes disposed in a circuit breaker case and urged by a contact spring, a contact opening and closing mechanism located above the contact shoes and including an opening and closing lever, a toggle link, an opening and closing handle and a latch, and an overcurrent tripping device located above the contact shoes. The toggle link includes a first link extending between the opening and closing lever and a toggle shaft located above, and a second link extending between the toggle shaft and the latch to overlap the first link in the V-form, and an opening and closing spring extends between the toggle shaft and a tip of a handle lever coupled to the opening and closing handle to extend downward. As a result, a space occupied by the contact opening and closing mechanism section in the height direction can be reduced to make the circuit breaker more compact.

Abstract: A circuit breaker (10) has a current carrying bimetallic element (18) which bends upon self-heating and upon being subjected to a selected overload current transfers motion to a connecting plate (32) which displaces a latch surface (42b) from a catch (34a) of a bell crank mechanism (34) allowing a spring biased operating member (28) to move movable contact means (12) out of contact engagement with stationary contact means (14) thereby tripping the circuit breaker. An arc sensing circuit (52) is coupled to the load circuit and upon sensing selected arcs causes an arc responsive actuator (56, 62) to be energized to transfer motion to the latch (42) to trip the circuit breaker.

Abstract: An electrical switch comprises a snap-acting actuator blade movable with a snap action between two configurations to control the making and breaking of electrical contacts and a latching mechanism which, when the actuator blade has snap-acted in one sense to break or make the contacts, prevents return movement of a movable contact carrying member until the latching mechanism has been positively released. The latching mechanism comprises a pivotal rigid member having an arm defining an engaging portion, for restraining return movement of the movable contact carrying member, and a biasing spring which urges the latching member in the movable contact carrying member engaging direction.