An arching fault protection system for a switchgear enclosure (10) includes a switching device (32) for rapidly diverting current from the source bus (22) of an electrical distribution system (12) in response to the detection of arcing faults in the system. The switching device (32), which may comprise a mechanical switch, a solid-state switch or hybrid device, quickly diverts current carried on the source bus (22) to effectively extinguish arcing fault currents present in the distribution system (12), preventing the generation of gases at high pressures and/or temperatures so as to protect the switchgear equipment from damage.

Arcing fault protection system for a switchgear enclosure

An arc fault detector system (10) detects arcing faults in an electrical distribution system by monitoring one or more conductors (14) and producing an input signal representing one or more electrical signal conditions in the circuit (12) to be monitored. This input signal is processed to develop signals representing the electrical current flow through the monitored circuit (12) and broadband noise signal components. The system (10) analyzes these signals to determine whether an arcing fault is present, and if so, outputs a trip signal which may be used directly or indirectly to trip a circuit breaker or other circuit interruption device (44).

Arc fault detection system

A ground fault circuit interrupter (GFCI) interrupts the flow of current through a pair of lines extending between a source of power and a load. The GFCI includes a circuit breaker having a switch located in one of the pair of lines. The switch has a first position in which the source of power in its associated line is not connected to the load and a second position in which the source of power in its associated line is connected to the load. A relay circuit is coupled to the switch for selectively positioning the switch in either the first or second position. The relay circuit includes a solenoid which operates in either an energized or a de-energized state. When energized, the solenoid positions the switch in its second position and when de-energized, the solenoid positions the switch in its first position. The GFCI also includes a booster circuit for selectively supplying a first voltage through the switch and to the solenoid which is sufficient to cause the solenoid to switch from its de-energized state to its energized state. A power supply circuit supplies a second voltage to the solenoid which is less than the first voltage. The second voltage is sufficient to maintain the solenoid in its energized state after being initially energized by the first voltage but is insufficient to switch the solenoid from its de-energized state to its energized state. A latch circuit operable in first and second bi-stable states allows the solenoid to switch from its de-energized state to its energized state and remain in its energized state when in its first bi-stable state and allowing solenoid to switch from its energized state to its de-energized state and remain in its de-energized state when in its second bi-stable state. A fault detecting circuit detects the presence of a fault condition in at least one of the lines extending between the power and the load and causes the latch circuit to latch in its second bi-stable state upon detection of the fault condition.

Ground fault circuit interrupter

In a circuit interrupter which has multiple electronic trip circuits, such as ground fault and arcing fault trip circuits, indicators such as LED's produce an indication of the cause of the trip The trip signals are latched to provide a continuing trip indication and ORed to actuate the trip device In one embodiment SCR's connected in series with the indicator LED's serve as the latches and are connected in parallel to the trip device to provide the OR function In other embodiments, flip-flops serve as the latches In one such embodiment, the indicator LED's are connected from the respective flip-flops in parallel to the trip device to provide the OR function In another such embodiment the flip-flops actuate the trip device and turn on switches actuating the LED's These switches energizing the cause of trip LED's are disabled until the contacts open to assure operation of the trip device Alarms can be coupled to the trip circuit by additional LED's, preferably IR LED's, connected in series with the indicator LED's

Circuit interrupter with cause for trip indication

An arc fault detector system detects arcing faults in an electrical distribution system by monitoring one or more conductors and producing an input signal representing one or more electrical signal conditions in the circuit to be monitored This input signal is processed to develop signals representing the electrical current flow through the monitored circuit and broadband noise signal components The system analyzes these signals to determine whether an arcing fault is present, and if so, outputs a trip signal which may be used directly or indirectly to trip a circuit breaker or other circuit interruption device

Arc fault detection for aircraft

A ground fault circuit breaker including ground fault interruption means and overload interruption means that are independently responsive to open a common set of breaker contacts upon respective ground fault and overload conditions with a trip indicator visible external to the breaker that operates on actuation of the ground fault interruption means but not upon operation of the overload interruption means with means for electrically actuating the trip indicator upon occurrence of a ground fault condition that actuates the ground fault interruption means.

Ronnie D. Davidson

Papers

Ground fault circuit breaker with ground fault trip indicator