Arc fault detector with circuit interrupter

• US 6,639,769 B2
• Filed: 04/11/2002
• Issued: 10/28/2003
• Est. Priority Date: 12/19/1997
• Status: Expired due to Term

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Campolo, Steve, Rose, William J., Neiger, Benjamin B., Bradley, Roger M., Pearse, James N.
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US10/120,462
• Publication Number:
  US 20020149891A1
• Time in Patent Office: 565 Days
• Field of Search: 361/42-50, 361/63, 361/78, 361/79, 361/88, 361/91.1, 361/93.1, 361/93.6, 361/94, 361/101, 702/58, 702/134, 702/FOR.103, 702/FOR.104, 702/FOR.105, 702/FOR.107, 324/508, 324/509, 324/512, 324/520, 324/525
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 1/043 to inrush currents H02H1/046 takes precedence; differential protection of transformers H02H7/045
• CPC Class Codes: H02H 3/334 with means to produce an artificial unbalance for other protection or monitoring reasons or remote control H02H3/338 takes precedence

Abstract

An arc fault circuit interrupter (AFCI) device functions to provide protection from potentially dangerous arc faults. The arc fault detector can be used stand alone or in combination with circuit interrupting devices such as IDCIs and ALCIs. The AFCI device detects both AC line frequencies and high frequencies associated with arcing. Both average and instantaneous values of both AC line frequency and high frequency arcing signals are processed to generate an arc fault signal. The trip mechanism of the device trips on the occurrence of either an arc fault or a ground fault. The device allows the arc detector to differentiate between destructive high level arcing and low level arcing such as generated by typical household appliances and equipment. This serves to decrease the occurrence of false tripping. The device also includes a timer circuit, which permits the user to temporarily disable the arc detector, and includes communication means to permit the device to communicate the occurrence and location of the arc fault to a centralized monitoring station.

Claims

1. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

arc fault circuit means for detecting the occurrence of an arc fault within said electrical wiring system, said arc fault circuit means operative to detect the current waveform of an AC signal on a conductor of the wiring system to obtain a first and second signal wherein the first signal, which is obtained from the high frequency content of the detected AC signal represents the level of arcing in the wiring system and the second signal represents the amount of current flowing through the wiring system where at least one of the signals is used to generate an arc fault trigger signal in response to the detection of an arc fault;

trigger means for generating a switching signal upon receipt of said arc fault trigger signal; and

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal.

2. The device according to claim 1, further comprising circuit interrupting means for interrupting the flow of current to a load electrically connected to said device in response to predetermined criteria.

3. The device according to claim 2, wherein said circuit interrupting means comprises ground fault circuit interrupter (GFCI) means for detecting the occurrence of a ground fault between said phase conductor and ground or between said neutral conductor and ground, said ground fault circuit means operative to generate a ground fault trigger signal in response to the detection of said ground fault.

4. The device according to claim 2, wherein said circuit interrupting means comprises immersion detection circuit interrupter (IDCI) means.

5. The device according to claim 2, wherein said circuit interrupting means comprises appliance leakage circuit interrupter (ALCI) means.

6. The device according to claim 1, wherein said arc fault circuit means comprises:

current measurement means for sensing the level of AC current flowing through an electrical load placed on said load side of said device;

high frequency circuit means for generating a peak high frequency signal and an average high frequency signal corresponding to the peak and average levels, respectively, of high frequency current flowing through said load;

AC line frequency circuit means for generating a peak AC line frequency signal and an average AC line frequency signal corresponding to the peak and average levels, respectively, of AC line frequency current flowing through said load; and

arc detect means for generating said arc fault trigger signal in accordance with said peak high frequency signal, said average high frequency signal, said peak AC line frequency signal and said average AC line frequency signal.

7. The device according to claim 6, wherein said arc detect means comprises means for generating said arc fault trigger signal when either said peak high frequency signal exceeds a first predetermined threshold or said peak AC line frequency signal exceeds a second predetermined threshold, the generation of said arc fault trigger signal providing an immediate response to dangerous levels of arcing or AC line current.

8. The device according to claim 6, wherein said arc detect means comprises means for generating said arc fault trigger signal when either said average high frequency signal exceeds a first predetermined threshold or said average AC line frequency signal exceeds a second predetermined threshold, the generation of said arc fault trigger signal providing an immediate response to dangerous levels of arcing or AC line current.

9. The device according to claim 1, wherein said arc fault circuit means comprises means for generating said arc fault trigger signal after a variable time delay dependent upon the level of arcing detected or on the level of AC line current detected.

10. The device according to claim 6, wherein said arc trigger circuit means comprises means for generating said arc fault trigger signal based on a plurality of arc fault trip levels which are dependent on the magnitude of the average AC line current.

11. The device according to claim 6, wherein said arc fault circuit means comprises means for generating said arc fault trigger signal based on a plurality of arc fault trip levels which are dependent on the level of AC line current detected.

12. The device according to claim 1, further comprising means for simultaneously detecting the peak and average magnitude of the high frequency arcing current and of the AC line current so as to provide an immediate response to dangerous levels in either arcing or AC line current.

13. The device according to claim 1, further comprising timer means for partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability to use an electrical device exhibiting arcing, said timer means enabling arc detection after use of said electrical device has been discontinued.

14. The device according to claim 1, further comprising communication means for communicating the generation of said switching signal.

15. The device according to claim 1, further comprising means for receiving a disable command and disabling arc detection in accordance therewith.

16. The device according to claim 1, further comprising means for a user to manually turn arc detection on and off.

17. The device according to claim 1, further comprising means for disabling arc detection during daylight hours and enabling arc detection during night hours.

18. The device according to claim 1, further comprising means for disabling and enabling arc detection in accordance with signals received from a remote infrared (IR) transmitter.

19. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

arc fault circuit means for detecting the occurrence of an arc fault within said electrical wiring system, said arc fault circuit means operative to detect the current waveform of an AC signal on a conductor of the wiring system to obtain a first and second signal wherein the first signal, which is obtained from the high frequency content of the detected AC signal represents the level of arcing in the wiring system and the second signal represents the amount of current flowing through the wiring system where at least one of the signals is used to generate an arc fault trigger signal in response to the detection of an arc fault;

trigger means coupled to said arc fault circuit means, said trigger means for generating a switching signal upon receipt of said arc fault trigger signal;

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal; and

timer means for partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability to use an electrical device exhibiting arcing, said timer means enabling arc detection after use of said electrical device has been discontinued.

23. The device according to claims 19, 20, 21 or 22, further comprising circuit interrupting means for interrupting the flow of current to a load electrically connected to said device in response to predetermined criteria.

24. The device according to claim 23, wherein said circuit interrupting means comprises ground fault circuit interrupter (GFCI) means for detecting the occurrence of a ground fault between said phase conductor and ground or between said neutral conductor and ground, said ground fault circuit means operative to generate a ground fault trigger signal in response to the detection of said ground fault.

25. The device according to claim 23, wherein said circuit interrupting means comprises immersion detection circuit interrupter (IDCI) means.

26. The device according to claim 23, wherein said circuit interrupting means comprises appliance leakage circuit interrupter (ALCI) means.

20. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

arc fault circuit means for detecting and splitting an AC signal on a conductor of the wiring system into two signals of different frequencies, the first for measuring the level of peak high frequency current and the second for measuring the peak AC line frequency current flowing through said device to an electrical load connected to said load side, wherein said arc fault circuit means is operative to generate an arc fault trigger signal when said first signal for measuring peak high frequency current exceeds a first predetermined threshold or when said second signal for measuring peak AC line frequency current exceeds a second predetermined threshold;

trigger means for generating a switching signal upon receipt of said arc fault trigger signal; and

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal.

27. The device according to claims 20, 21 or 22, further comprising means for partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability use an electrical device exhibiting arcing, said timer means enabling arc detection after use of said electrical device has been discontinued.

28. The device according to claims 20, 21 or 22, further comprising communication means for communicating the generation of said switching signal.

29. The device according to claims 20, 21 or 22, further comprising means for receiving a disable command and disabling arc detection in accordance therewith.

30. The device according to claims 20, 21 or 22, further comprising means for a user to manually turn arc detection on and off.

31. The device according to claims 20, 21 or 22, further comprising means for disabling arc detection during daylight hours and enabling arc detection during night hours.

32. The device according to claims 20, 21 or 22, further comprising means for disabling and enabling arc detection in accordance with signals received from a remote infrared (IR) transmitter.

21. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

arc fault circuit means for detecting and splitting an AC signal on a conductor of the wiring system into two signals of different frequencies, the first signal for measuring the level of average high frequency current and the second signal for measuring the average AC line frequency current flowing through said device to an electrical load connected to said load side, wherein said arc fault circuit means is operative to generate an arc fault trigger signal when said average high frequency current of the first signal exceeds a first predetermined threshold or when said average AC line frequency current of the second signal exceeds a second predetermined threshold;

trigger means coupled to said arc fault circuit means, said trigger means for generating a switching signal upon receipt of said arc fault trigger signal; and

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal.

22. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

arc fault circuit means for detecting and splitting an AC signal on a conductor of the wiring system into two signals of different frequencies, the first signal for measuring the level of average high frequency current and the second signal for measuring the average AC line frequency current flowing through said device to an electrical load connected to said load side, said arc fault circuit means operative to generate an arc fault trigger signal utilizing a plurality of trip levels of said average high frequency current of the first signal based on said level of average AC line frequency current of the second signal;

trigger means coupled to said arc fault circuit means, said trigger means for generating a switching signal upon receipt of said arc fault trigger signal; and

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal.

33. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

current measuring means for sensing the level of current flowing through one of either said line side phase or neutral conductors for detecting and splitting an AC signal on a conductor of the wiring system into first and second signals of different frequencies;

high frequency means coupled to receive said first signal for generating a high frequency signal corresponding to the level of high frequency current sensed by said current measurement means;

AC line frequency means coupled to receive said second signal for generating an AC line frequency signal corresponding to the level of AC line frequency current sensed by said current measurement means;

arc detect means for generating an arc fault trigger signal in accordance with said high frequency signal and said AC line frequency signal;

trigger means for generating a switching signal upon receipt of said arc fault trigger signal;

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal; and

timer means for partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability to use an electrical device exhibiting arcing, said timer means enabling arc detection after use of said electrical device has been discontinued.

36. The device according to claim 33, further comprising communication means for communicating the generation of said switching signal.

37. The device according to claims 33 or 34, further comprising means for receiving a disable command and disabling arc detection in accordance therewith.

38. The device according to claims 33 or 34, further comprising means for a user to manually turn arc detection on and off.

39. The device according to claims 33 or 34, further comprising means for disabling arc detection during daylight hours and enabling arc detection during night hours.

40. The device according to claims 33 or 34, further comprising means for disabling and enabling arc detection in accordance with signals received from a remote infrared (IR) transmitter.

41. The device according to claims 33 or 34, further comprising circuit interrupting means for interrupting the flow of current to a load electrically connected to said device in response to predetermined criteria.

42. The device according to claim 41, wherein said circuit interrupting means comprises ground fault circuit interrupter (GFCI) means for detecting the occurrence of a ground fault between said phase conductor and ground or between said neutral conductor and ground, said ground fault circuit means operative to generate a ground fault trigger signal in response to the detection of said ground fault.

43. The device according to claim 41, wherein said circuit interrupting means comprises immersion detection circuit interrupter (IDCI) means.

44. The device according to claim 41, wherein said circuit interrupting means comprises appliance leakage circuit interrupter (ALCI) means.

34. An arc fault circuit interrupter (AFCI) device electrically connected to an electrical wiring system between a source of electrical power including line side phase and neutral conductors and a load side including phase and neutral conductors, said device comprising:

current measuring means for sensing the level of current flowing through one of either said line side phase or neutral conductors for detecting and splitting an AC signal on a conductor of the wiring system into first and second signals of different frequencies;

high frequency means coupled to receive said first signal for generating a high frequency signal corresponding to the level of high frequency current sensed by said current measurement means;

AC line frequency means coupled to receive said second signal for generating an AC line frequency signal corresponding to the level of AC line frequency current sensed by said current measurement means;

arc detect means for generating an arc fault trigger signal in accordance with said high frequency signal and said AC line frequency signal; and

switching means electrically connected in series between said line side phase and neutral conductors and said load side phase and neutral conductors, said switching means for disconnecting said source of electrical power to said load side phase and neutral conductors in response to said arc fault trigger signal.

35. The device according to claim 34, further comprising means for partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability use an electrical device exhibiting arcing, said timer means enabling arc detection after use of said electrical device has been discontinued.

45. In an arc fault circuit interrupter (AFCI) device connected to an electrical wiring system via line side phase and neutral conductors and load side phase and neutral conductors, a method of detecting arc faults and ground faults, comprising the steps of:

sensing the level of current flowing through one of either said line side phase or neutral conductors to detect and split an AC signal on a conductor of the wiring system into first and second signals of different frequencies;

generating from said first signal a high frequency signal corresponding to the level of high frequency current sensed;

generating from said second signal an AC line frequency signal corresponding to the level of AC line frequency current sensed;

generating an arc fault trigger signal in accordance with said high frequency signal and said AC line frequency signal;

generating a switching signal in response to said arc fault trigger signal; and

disconnecting said source of electrical power to said load side phase and neutral conductors in response to said switching signal.

46. The method according to claim 45, further comprising the step of partially disabling arc detection for a finite period of time, the disabling of arc detection providing a user with the ability use an electrical device exhibiting arcing, and enabling arc detection after use of said electrical device has been discontinued.

47. The method according to claim 45, further comprising the step of communicating the generation of said switching signal.

48. The method according to claim 45, further comprising the step of receiving a disable command and disabling arc detection in accordance therewith.

49. The method according to claim 45, further comprising the step of providing the ability for a user to manually turn arc detection on and off.

50. The method according to claim 45, further comprising the step of disabling arc detection during daylight hours and enabling arc detection during night hours.

51. The method according to claim 45, further comprising the step of disabling and enabling arc detection in accordance with signals received from a remote infrared (IR) transmitter.

52. The method according to claim 45, further comprising the steps of:

detecting the occurrence of a ground fault between said phase conductor and ground or between said neutral conductor and ground; and

generating a ground fault trigger signal in response to the detection of said ground fault.