Abstract: A circuit breaker has contacts which are engageable as a result of manual operation of a toggle mechanism causing the circuit breaker to close and open when the toggle is in an erect and collapsed condition, respectively. Subsequent opening of the circuit breaker is accomplished by either manual operation or automatic due to a current responsive latch within the toggle mechanism. As a result of a unique movable contact biasing arrangement, more uniform pressure is obtained between the contacts and a wiping action of the contacts is obtained during closing. The movable contact is mounted on a contact member pivoted at its center on a solid pin mounted in the breaker case through an elongated aperture in the contact member. The elongated aperture allows for a limited degree of movement of the contact member transverse to the pivot pin. It is this limited transverse movement which increases the tolerance range by providing overtravel of the movable contact and wiping action of the contacts.

Abstract: A circuit breaker has contacts engageable as a result of manual operation of a toggle mechanism causing the circuit breaker to close and open when the toggle is in an erect and collapsed condition, respectively. A push-off spring is used to bias a moveable contact away from a stationary contact to accelerate movement of the moveable contact during opening of the circuit breaker. Minimal manual effort is required to close the circuit breaker while providing greatly increased pressure for accelerating opening of the circuit breaker through use of a unique push-off spring which provides a first, lower, degree of resistance to closing of the contacts during the initial operation of the circuit breaker while providing a second, higher, degree of resistance to closing of the contacts after the initial operation. Manual closing of the circuit breaker is unimpeded by the second, higher, degree of resistance after the initial operation of the breaker.

Abstract: A circuit breaker for interrupting current through plural electrical circuits has a separate current responsive circuit path for each electrical circuit. Each path includes a manually operable latching mechanism capable of engaging and disengaging a pair of electrical contacts on demand and further includes a circuit responsive releaseable latch mechanism for automatically disengaging the pair of contacts. A common manually activated handle is connected to each of the latching mechanisms to enable manual and automatic operation of the breaker for simultaneous engagement or disengagement of the paired electrical contacts. The connection of the common handle to the several latching mechanisms encompasses a trip bar arranged for both pivotal movement about an axis parallel to the axis of the handle and sliding movement relative to guides within a common insulating case of the circuit breaker.

Abstract: The disclosed circuit breaker includes a movable contact which enters the space between stationary contact jaws, the movable contact acting through a spring to bias a jaw-closing toggle toward erect condition, so that contacts on the contact jaws firmly grip the movable contact.

Abstract: The present invention relates to circuit breakers of a particular class, namely, the type in which a toggle is manually erected to drive a "heart" as a unit for closing the circuit breaker. The "heart" includes a contact arm, an actuator, and overcurrent releasable latch means which collectively form a normally latched unit. Under excess-current conditions, the latch means releases the actuator, and contact arm then opens the circuit.The latch means includes a conventional bimetal fixed at one end to the contact arm. The bimetal carries a pivoted latch lever, and is surrounded by a core-and-armature unit adjacent its secured end, for operating the latch lever in response to high overcurrents. High magnetic trip sensitivity is achieved in a construction wherein the whole electromagnet moves with the contact arm, without resort to a current-carrying coil for the electromagnet.

Abstract: In a distribution circuit for connecting a load to an a-c source, it is known that a ground-to-neutral short tends to reduce the sensitivity of ground fault detectors that use a differential current transformer to sense line-to-ground leakage. A resonated coil on a core links the neutral conductor forming part of a protective device for interrupting the load circuit in the event of reduced Q of the resonated coil caused by a neutral-to-ground fault. The core must also link the line conductor, for otherwise a loop including the line, the load and the neutral would wrongly have a like effect.The same core and coil are used with a common amplifier for the neutral-to-ground fault detector and for the line-to-ground leakage detector, so that the apparatus can be economical and compact. Furthermore, so long as there is no neutral-to-ground fault, the amplifier delivers a signal of normal strength that monitors the integrity of both detectors.

Abstract: A panelboard front assembly including a trim plate having an opening for exposing a panel assembly mounted in a box, clamping bars slidably attached to the trim plate for engaging flanges of the box, and a door attached to the trim plate which conceals the clamping bars and the associated adjusting means when closed. In the illustrated example, side rabbets are provided on the trim plate and the clamping bars slide in openings in the rabbets and have adjusting screws which slide in slots in the rabbets. The clamping bars are further spring-loaded toward the open position by springs situated proximate the adjusting screws.

Abstract: Circuit-breaker system having a response time to shortcircuits of less than 4 milliseconds have multiple coordinated pole units wired in series in each phase. The system is able to clear a fault where the available current is high, for example 100,000 amperes at 240 volts AC although each pole unit may be of conventional construction having a current-interruption rating of only 5 or 10 thousand amperes. The operation exhibits current limiting properties, and the interruption process leaves the pole units remarkably free of arc damage.