Arc fault circuit interrupter

• US 6,414,829 B1
• Filed: 12/07/1999
• Issued: 07/02/2002
• Est. Priority Date: 02/19/1998
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Grattan, Brian G., Scott, Gary W., Dvorak, Robert F., Wong, Kon B., Haun, Andy A.
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US09/454,565
• Time in Patent Office: 938 Days
• Field of Search: 361/42-50, 324/520, 324/522, 324/536, 324/613
• US Class Current: 361/42
• CPC Class Codes: H01H 2083/201 the other abnormal electrical condition being an arc fault
• CPC Class Codes: H01H 2300/03 Application domotique, e.g. for house automation, bus connected switches, sensors, loads or intelligent wiring
• CPC Class Codes: H01H 71/125 characterised by sensing elements, e.g. current transformers for differential protection H01H83/144
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 1/06 Arrangements for supplying operative power power supply arrangements in general G05F, H02M
• CPC Class Codes: H02H 3/105 responsive to excess current and fault current to earth
• CPC Class Codes: H02H 3/44 responsive to the rate of change of electrical quantities
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/14 Protecting elements, switches, relays or circuit breakers
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A system for producing a simulated ground fault when arcing is present in an electrical circuit includes a sensor which monitors the electrical circuit. An arcing fault detection circuit determines whether an arcing fault is present in response to the sensor and produces a trip signal in response to a determination that an arcing fault is present in the electrical circuit. A ground fault simulator circuit produces a simulated ground fault in response to the trip signal.

Claims

1. A system for producing a simulated ground fault when arcing is present in an electrical circuit, comprising:

a sensor which monitors said electrical circuit,

an arcing fault detection circuit which determines whether an arcing fault is present in said electrical circuit in response to said sensor and produces a trip signal in response to a determination that an arcing fault is present in said electrical circuit,

a ground fault simulator circuit which produces a simulated ground fault in response to said trip signal;

wherein said sensor detects a current in said electrical circuit and develops a corresponding sensor signal, wherein said arcing fault detection circuit comprises a circuit which determines the presence of broadband noise in said sensor signal and produces a corresponding output signal, and a controller which processes said sensor signal and said output signal in a predetermined fashion to determine whether an arcing fault is present in said electrical circuit and

wherein the controller implements a plurality of counters and increments said plurality of counters in a predetermined fashion in accordance with said sensor signal and said output signal, and periodically determines whether an arcing fault is present based at least in part on the state of said plurality of counters.

2. The system of claim 1 wherein said counters are implemented in software.

3. The system of claim 1 wherein said ground fault simulator circuit has an input for receiving said trip signal and an output for producing said simulated ground fault, and wherein said output is electrically isolated from said input.

4. The system of claim 3 wherein said ground fault simulator circuit comprises a relay.

5. The system of claim 3 wherein said ground fault simulator circuit comprises an opto-isolator.

6. The system of claim 5 wherein said opto-isolator includes an opto-triac.

7. The system of claim 5 wherein said opto-isolator includes an opto-transistor.

8. The system of claim 5 wherein said opto-isolator comprises an opto-SCR.

9. A method of producing a simulated ground fault when arcing is present in an electrical circuit comprising:

monitoring said electrical circuit and determining whether an arcing fault is present in sad circuit;

producing a trip signal in response to a determination that an arcing fault is present in said electrical circuit;

producing a simulated ground fault in response to said trip signal;

wherein the monitoring and determining include sensing a current in the electrical circuit and developing a corresponding sensor signal, determining the presence of broadband noise in said sensor signal and producing a corresponding output signal and processing said sensor signal and said output signal in a predetermined fashion to determine whether an arcing fault is present in said electrical circuit; and

wherein said processing includes incrementing a plurality of counters in a predetermined fashion in accordance with said sensor signal and said output signal, and periodically determining whether an arcing fault is present based at least in part on the state of said plurality of counters.

10. The method of claim 9 and further including implementing said plurality of counters in software.

11. The method of claim 9 wherein producing a simulated ground fault includes electrically isolating said simulated ground fault from said trip signal.