Abstract: Demonstrator apparatus utilizes a display to portray in log-log coordinate scale the trip-time curve of a solid state (static) trip circuit breaker. A simulated static trip unit programmer is selectively adjustable to vary the shape and position of the displayed trip-time curve. An overlay bearing the trip time-current curve for a prospective upstream or downstream circuit protective device is superimposed on the display and the programmer adjusted to demonstrate selective trip coordination. Alternatively, a pair of simulated trip unit programmers are connected to the display to jointly portray thereon a pair of trip-time curves. Also disclosed is the utilization of a computer to generate on a display plural time-current response curves of a series of circuit protective devices selected on the basis of specific distribution system parameters to provide requisite system protection and response coordination.

Abstract: A unique ground fault circuit interrupting (GFCI) device is utilized to control either an industrial circuit breaker or a contactor in protecting a large power distribution circuit against ground faults. The GFCI device is equipped with plural sets of switch contacts which are actuated incident with tripping of the GFCI device. The particular switch contacts are selected to control energization of an actuator adapted to the circuit breaker or contactor, depending on the actuator type. A ground fault sensor responds to ground faults on the distribution circuit by injecting a current imbalancing signal into the GFCI device, causing it to trip. The consequent switch contact actuation initiates operation of the circuit breaker or contactor to interrupt the distribution circuit.

Abstract: A ground fault circuit interrupting (GFCI) device is utilized to control either an industrial circuit breaker or a contactor in protecting a large power distribution circuit against ground faults. The GFCI device is equipped with switch contacts which are actuated incident with tripping of the GFCI device. The switch contacts control energization of an actuator adapted to the circuit breaker or contactor. A ground fault sensor responds to ground faults on the distribution circuit by injecting a current imbalancing signal into the GFCI device, causing it to trip. The consequent switch contact actuation initiates operation of the circuit breaker or contactor to interrupt the distribution circuit.

Abstract: A ground fault circuit interrupting (GFCI) device of the type utilized in low voltage, residential type circuits for personnel protection against ground faults is connected in circuit with a high voltage, high current source so as to trip in response to ground fault current returning to the source via a conductor path solidly connecting the source to ground.

Abstract: A conventional residential ground fault circuit interrupting (GFCI) device is utilized to control a traditional circuit interrupter in protecting a large power distribution circuit against ground faults. The GFCI device is connected in an energization circuit for a solenoid operable to open the interrupter contacts. A sensor responds to ground faults on the distribution circuit by impressing the current signal on one side of the energization circuit, thus creating a current imbalance effective to trip the GFCI device. Interruption of the energization circuit causes the solenoid to initiate opening of the interrupter contacts. In an alternative embodiment, the GFCI device is adapted to initiate opening of the interrupter contacts upon degradation of ground circuit continuity.

Abstract: A conventional residential ground fault circuit interrupting (GFCI) device is utilized to control a traditional circuit interrupter in protecting a large power distribution circuit against ground faults. The GFCI device is connected in an energization circuit for a solenoid operable to open the interrupter contacts. A sensor responds to ground faults on the distribution circuit by impressing the current signal on one side of the energization circuit, thus creating a current imbalance effective to trip the GFCI device. Interruption of the energization circuit causes the solenoid to initiate opening of the interrupter contacts. In an alternative embodiment, the GFCI device is adapted to initiate opening of the interrupter contacts upon degradation of ground circuit continuity.