Abstract: A circuit that includes a single grounded fault sensing transformer coupled to a resonant circuit that produces an output signal used by a microcontroller to determine a load current flowing through at least two conductors passing through the center of the sensing transformer. The microcontroller pings the resonant circuit, causing an impulse disturbance at the output signal, and the microcontroller calculates the inductance component of the resonant circuit based on the frequency of the decaying output signal. The microcontroller calculates the resistive core loss as a function of a known resistance of the resonant circuit, a known capacitance of the resonant circuit, the calculated inductance, and the determined rate of decay of the output signal. The calculated resistive core loss is compared to a table or to a polynomial function that characterizes known resistive core losses with known load currents to determine the load current corresponding to the calculated resistive core loss.

Abstract: A circuit breaker is disclosed that has a bi-stable display that maintains an indication of a fault condition after power is interrupted to the circuit breaker. The circuit breaker has a microcontroller that receives power derived from a line current that passes through the circuit breaker or the line voltage when the circuit breaker is in an on state. The bi-stable display is electrically coupled to and controlled by the microcontroller. A tripping mechanism trips the circuit breaker in response to detection of a fault condition. The tripping mechanism trips the circuit breaker in response to receiving a trip signal from the microcontroller. The microcontroller is programmed to modify the bi-stable display when sending the trip signal to the electronic switching device. The bi-stable display shows an indication of one of the several fault types that would have caused the circuit breaker to trip.

Abstract: A latch mechanism for a circuit breaker comprises a pair of longitudinal legs, a lateral section bridging the pair of longitudinal legs, and a longitudinal section extending from the lateral section in an opposite direction relative to the pair of legs. The lateral section includes a lower bearing surface for releasably engaging a cradle of the circuit breaker. The lower bearing surface includes a coined radius for facilitating engagement and disengagement of the cradle. The longitudinal section includes a protrusion for supporting a latch spring. The latch mechanism is manufactured in a single stamping operation, during which the protrusion is formed by cold extrusion.

Abstract: A circuit breaker includes a first section and a second section with substantially independently operating pairs of contact assemblies in each respective section. In the first section, at least one of the contact assemblies is constructed and arranged to interrupt the current by moving from a normally closed position to a blown-open position and latching with the contact assemblies separated. The second section has a biasing extension spring for biasing the contact assemblies of the second section so as to permit interruption of the current in response to a blow-open force, which causes the contacts to separate only momentarily and then return to a normally closed position. The first and second pairs of contact assemblies separate substantially simultaneously in response to the blow-open force, and only the first section reacts to lower-level over-current conditions.

Abstract: The present invention provides a mechanism for controlling the incremental release and subsequent resetting of a charging mechanism to slowly close an electrical contact operating mechanism of a circuit breaker. The slow close mechanism includes a frame defined by a pair of spaced, generally parallel sideplates connected together and terminating with support legs. The support legs have guide slots to receive a shaft of the charging mechanism. A support block rotatably connects between the sideplates and supports the shaft along the length of the guide slots as the support block rotates. An elongated arm slidingly couples to one of the support legs and has a flange at one end for manual operation. The opposite arm end rotatably couples to a crank arm extending through the one support leg to connect with the support block so that pulling the flange slides the arm and rotates the crank arm and the support block to control the travel of the shaft of the charging mechanism down the guide slots.

Abstract: A circuit breaker is provided having an operating mechanism for rotating a blade about a pin between an OPEN position and a CLOSED position, thereby separating and engaging a stationary contact and a movable contact which is secured to the blade. The operating mechanism has a frame and a first link coupled at one end thereof to the frame and its opposite end coupled to a first end of a second link. The operating mechanism further includes a third link having a first end coupled to a second end of the second link and a second end coupled to the blade for moving the blade between the OPEN position and the CLOSED position. The first and second links are disposed on the opposite side of the pin from the movable contact.