Abstract: A three pole molded case circuit breaker including a push-to-trip button, a flux transfer shunt trip mechanism, an undervoltage trip mechanism, and an improved latch mechanism. The latch mechanism comprises a metal trip bar covered with insulating tubing and adapted for translational movement to actuate the latch mechanism and trip the contacts. Contact carrier movement during the tripping operation serves to reset the latch mechanism.

Abstract: A circuit breaker having stationary and movable contacts operable between open and closed positions. Movement effecting means causes relative movement of the movable contact between open and closed positions, and a closing spring assembly imparts movement to the movement effecting means to move the movable contact to the closed position. The closing spring assembly includes first and second members and a helical closing spring, with the first and second members extending into the central opening of the spring. Shock absorbing means is disposed within the spring opening to absorb energy released when the assembly is discharged.

Abstract: A circuit breaker comprises a stored-energy mechanism and a resettable roller-type latch for latching the stored-energy mechanism. The latch is operable upon the occurrence of overload current conditions to release the stored-energy mechanism to thereby trip the breaker. Alternately the latch may be actuated by utilizing a separate switch.

Abstract: A molded case circuit breaker having thermal and magnetic trip means. A moving contact support structure is disposed about the magnetic trip means so as to cause current flowing through the circuit breaker contacts to pass twice through the magnetic circuit of the magnetic trip means. The moving contact support structure includes resistance material operable upon overcurrent conditions through the contacts to aid in heating the thermal trip means. An operating mechanism includes an operating spring in compression which acts as one leg of a toggle linkage and stores energy to operate the contacts with a snap action.

Abstract: A circuit interrupter for a power control system which is characterized by a circuit breaker and an electrically insulating housing, which housing comprises separable molded portions. The circuit breaker comprising at least two sets of pairs of movable and stationary contacts in stacked relationship, the stationary contacts being mounted on internal conductors extending through aligned openings in the housing and being connectable to external conductors. The housing has molded support means for retaining the internal conductors in stacked aligned positions. The movable contacts are mounted on movable contact means including bridging contact members and an actuator for moving the bridging contact members in unison between open and closed positions of the contact. Solenoid means are provided for closing the contacts. In addition, a slot motor can be provided on the bridging contact members for opening the circuit in response to a very high current overload in order to provide a current limiting type breaker.

Abstract: A molded case circuit breaker having a solid-state trip unit adjustable over a variety of ratings. One-way adjustment is provided, permitting a reduction in the rating of the circuit breaker and preventing an increase in the rating. A ratchet mechanism and a one-way screw mechanism are provided to implement the one-way adjustment.

Abstract: A relatively simple trip or control circuit for a circuit breaker in which the time constant for an input signal related to the amount of current flowing in the lines to be protected is purposely made relatively large so that tripping is slightly delayed for approximately three-half cycles of line current for overload currents in the range of 500 to 1000% of rated current. A Zener diode resistive network is used in combination therewith for providing near instantaneous tripping in the range of overload current above 1000%. The short delay is useful for preventing circuit breaker tripping when overloads of the spurious or transient type are impressed occasionally on the electrical conductors of the circuit being protected. The delay characteristic is not purposely related to any function of the overload current but is rather arbitrarily chosen to be greater than approximately 25 milliseconds because most spurious or transient signals have a duration of less time.

Abstract: A molded case circuit breaker is described including a U-shaped thermal and magnetic trip assembly pivotally supported by an insulating housing. A compression spring biases the trip assembly against a releasable cradle which is engaged by a latch. The biasing action of the spring against the pivoting trip assembly maintains a constant latch bite despite warping or other mechanical distortion of the insulating housing.