Arc fault detector with circuit interrupter

• US 6,088,205 A
• Filed: 12/19/1997
• Issued: 07/11/2000
• 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, Bradley, Roger M., Rose, William J., Pearse, James N., Neiger, Benjamin B.
• Primary Examiner(s): Leja, Ronald W.
• Application Number:
  US08/995,130
• Time in Patent Office: 935 Days
• Field of Search: 361/42-50, 361/63, 361/78, 361/79, 361/88, 361/91, 361/93, 361/94, 361/111, 361/93.1, 361/93.6, 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. A circuit interrupting device capable of being electrically connected to an electrical wiring system between line side phase and neutral conductors and load side phase and neutral conductors, the device comprising:

switching means for disconnecting a source of electrical power between at least the line side phase conductor to the load side phase conductor;

trigger circuit means for causing said switching means to disconnect the source of electrical power to the load side phase conductor; and

arc fault detecting means for detecting in said electrical wiring system arc faults occurring in a high frequency range and arc faults occurring in an AC line frequency range, and for generating a trigger signal in response to the occurrence of an arc fault in at least one of said high frequency range and said AC line frequency range that activates said trigger circuit means.

2. The device according to claim 1, wherein said high frequency range is at least about 500 KHz.

3. The device according to claim 1, wherein said AC line frequency range is between about 50 Hz. and about 60 Hz.

4. The device according to claim 1, wherein said arc fault detecting means uses peak and average signals in said high frequency range to detect arc faults occurring in said high frequency range.

5. The device according to claim 1, wherein said arc fault detecting means uses peak and average signals in said AC line frequency range to detect arc faults occurring in said AC line frequency range.

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

current measurement means for sensing a level of current flowing through the device;

high frequency circuit means for generating said peak and average high frequency signals, wherein said peak high frequency signal corresponds to a peak level of high frequency current flowing through the device, and wherein said average high frequency signal corresponds to an average level of high frequency current flowing through the device;

AC line frequency circuit means for generating peak and average AC line frequency signals, wherein said peak AC line frequency signal corresponds to a peak level of AC line frequency current flowing through the device, and wherein said average AC line frequency signal corresponds to an average level of AC line frequency current flowing through the device; and

means for generating said trigger signal.

7. The device according to claim 6, wherein said means for generating said trigger signal generates said trigger signal when either said peak high frequency signal exceeds a predetermined threshold or said peak AC line frequency signal exceeds a predetermined threshold.

8. The device according to claim 6, wherein said means for generating said trigger signal generates said trigger signal when either said average high frequency signal exceeds a predetermined threshold or said average AC line frequency signal exceeds a predetermined threshold.

9. The device according to claim 6, wherein said means for generating said trigger signal generates said trigger signal after a time delay, said time delay being dependent upon a level of arcing detected or on a level of said sensed current.

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

11. The device according to claim 6, wherein said means for generating said trigger signal generates said trigger signal based on a plurality of arc fault trip levels which are dependent on a level of said sensed current.

12. The device according to claim 1, further comprising means for at least partially disabling said arc fault detecting means for a finite period of time to permit a user to use an electrical device exhibiting arcing, and for enabling said disabled arc fault detecting means after use of the electrical device exhibiting arcing has been discontinued.

13. The device according to claim 1, further comprising means for receiving an external disable command and disabling at least a portion of said arc fault detecting means.

14. The device according to claim 1, further comprising means for manually disabling and enabling at least a portion of said arc fault detecting means.

15. The device according to claim 1, further comprising means for disabling at least a portion of said arc fault detecting means during daylight hours, and for enabling said disabled portion of said arc fault detecting means during night hours.

16. The device according to claim 1, further comprising means for disabling and enabling at least a portion of said arc fault detecting means in accordance with signals received from a remote transmitter.

17. The device according to claim 1, further comprising fault detection means for detecting a fault other than an arc fault, and for activating said trigger circuit means when a fault other than an arc fault is detected.

18. The device according to claim 17, wherein said fault detection means comprises a ground fault circuit interrupter capable of detecting the occurrence of a ground fault and generating a trigger signal in response to the detection of the ground fault that activates said trigger circuit means.

19. The device according to claim 17, wherein said fault detection means comprises an immersion detection circuit interrupter capable of detecting the occurrence of an immersion fault and generating a trigger signal in response to the detection of the immersion fault that activates said trigger circuit means.

20. The device according to claim 17, wherein said fault detection means comprises an appliance leakage circuit interrupter capable of detecting the occurrence of an appliance leakage fault and generating a trigger signal in response to the detection of the appliance leakage fault that activates said trigger circuit means.

21. The device according to claim 1, further comprising communication means for communicating when said trigger circuit means causes said switching means to disconnect the source of electrical power to said load side phase conductor.

22. A circuit interrupting device capable of being electrically connected to an electrical wiring system between line side phase and neutral conductors and load side phase and neutral conductors, the device comprising:

a switch capable of disconnecting a source of electrical power between at least the line side phase conductor and the load side phase conductor;

a trigger circuit that causes said switch to disconnect the source of electrical power to the load side phase conductor;

an arc fault detector operatively associated with at least one of the phase and neutral conductors of the electrical wiring system to sense current flowing through the device, said arc fault detector being capable of generating peak and average high frequency signals and peak and average AC line frequency signals from the sensed current, and capable of detecting arc faults in said AC high frequency and AC line frequency signals and generating a trigger signal in response to at least one of said peak high frequency signal, said average high frequency signal, said peak AC line frequency signal and said average AC line frequency signal, that activates said trigger circuit.

23. The device according to claim 22, wherein said arc fault detector comprises:

a high frequency circuit that receives the sensed current and generates said peak and average high frequency signals, wherein said peak high frequency signal corresponds to a peak level of high frequency current flowing through the device, and wherein said average high frequency signal corresponds to an average level of high frequency current flowing through the device; and

an AC line frequency circuit that receives the sensed current and generates said peak and average AC line frequency signals, wherein said peak AC line frequency signal corresponds to a peak level of AC line frequency current flowing through the device, and wherein said average AC line frequency signal corresponds to an average level of AC line frequency current flowing through the device.

24. The device according to claim 22, wherein said arc fault detector generates said trigger signal when either said peak high frequency signal exceeds a predetermined threshold or said peak AC line frequency signal exceeds a predetermined threshold.

25. The device according to claim 22, wherein said arc fault detector generates said trigger signal when either said average high frequency signal exceeds a predetermined threshold or said average AC line frequency signal exceeds a predetermined threshold.

26. The device according to claim 22, wherein said arc fault detector generates said trigger signal after a time delay, said time delay being dependent upon a level of arcing detected from said sensed current.

27. The device according to claim 22, wherein said arc fault detector generates said trigger signal based on a plurality of arc fault trip levels which are dependent on a magnitude of said average AC line frequency current.

28. The device according to claim 22, wherein said arc fault detector generates said trigger signal based on a plurality of arc fault trip levels which are dependent on said sensed current.

29. The device according to claim 22, further comprising means for simultaneously detecting peak and average magnitudes of said high frequency current and said AC line frequency current.

30. The circuit interrupting device according to claim 22, further comprising timer means for at least partially disabling said arc fault detection for a finite period of time to permit a user to use an electrical device exhibiting arcing, and for re-enabling said first arc fault detecting means after use of the electrical device exhibiting arcing has been discontinued.

31. The circuit interrupting device according to claim 22, further comprising a fault detector capable of detecting a fault other than an arc fault, and for activating said trigger circuit when a fault other than an arc fault is detected.

32. The circuit interrupting device according to claim 31, wherein said fault detector comprises a ground fault circuit interrupter capable of detecting the occurrence of a ground fault and generating a trigger signal in response to the detection of the ground fault that activates said trigger circuit.

33. The circuit interrupting device according to claim 31, wherein said fault detector comprises an immersion detection circuit interrupter capable of detecting the occurrence of an immersion fault and generating a trigger signal in response to the detection of the immersion fault that activates said trigger circuit.

34. The circuit interrupting device according to claim 31, wherein said fault detector comprises an appliance leakage circuit interrupter capable of detecting the occurrence of an appliance leakage fault and generating a trigger signal in response to the detection of the appliance leakage fault that activates said trigger circuit.

35. An arc fault circuit interrupter device capable of being electrically connected to an electrical wiring system between line side phase and neutral conductors and load side phase and neutral conductors, said device comprising:

a switch connected between at least said line side phase conductor and said load side phase conductor;

a trigger circuit operatively connected to said switch such that activation of said trigger circuit causes said switch to disconnect a source of electrical power to the load side phase conductor; and

an arc fault detector capable of detecting in said electrical wiring system arc faults occurring in a high frequency range and arc faults occurring in an AC line frequency range, said arc fault detector responding to the detection of an arc fault in at least one of said high frequency range and said AC line frequency range by generating a trigger signal that causes said trigger circuit to activate said switch.

36. The device according to claim 35, wherein said high frequency range is at least about 500 KHz.

37. The device according to claim 35, wherein said AC line frequency range is between about 50 Hz. and about 60 Hz.

38. The device according to claim 35, wherein said arc fault detector uses peak and average signals in said high frequency range to detect arc faults occurring in said high frequency range.

39. The device according to claim 35, wherein said arc fault detector uses peak and average signals in said AC line frequency range to detect arc faults occurring in said AC line frequency range.

40. The device according to claim 35, wherein said arc fault detector comprises:

a current measurement circuit capable of sensing current flowing through the device;

a high frequency circuit capable of generating peak and average high frequency signals, wherein said peak high frequency signal corresponds to a peak level of high frequency current flowing through the device, and wherein said average high frequency signal corresponds to an average level of high frequency current flowing through the device;

an AC line frequency circuit capable of generating peak and average AC line frequency signals, wherein said peak AC line frequency signal corresponds to a peak level of AC line frequency current flowing through the device, and wherein said average AC line frequency signal corresponds to an average level of AC line frequency current flowing through the device; and

a trigger generator circuit responsive to at least one of said peak high frequency signal, said average high frequency signal, said peak AC line frequency signal and said average AC line frequency signal, to generate said trigger signal.

41. The device according to claim 40, wherein said trigger generator circuit generates said trigger signal when either said peak high frequency signal exceeds a predetermined threshold or said peak AC line frequency signal exceeds a predetermined threshold.

42. The device according to claim 40, wherein said trigger generator circuit generates said trigger signal when either said average high frequency signal exceeds a predetermined threshold or said average AC line frequency signal exceeds a predetermined threshold.

43. The device according to claim 40, wherein said trigger generator circuit generates said trigger signal after a time delay, said time delay being dependent upon a level of arcing detected or on a level of said sensed current.

44. The device according to claim 40, wherein said trigger generator circuit generates said trigger signal based on a plurality of arc fault trip levels which are dependent on a magnitude of said average AC line frequency current.

45. The device according to claim 40, wherein said trigger generator circuit generates said trigger signal based on a plurality of arc fault trip levels which are dependent on a level of AC line frequency current.

46. The device according to claim 35, further comprising an arc detection disabling circuit capable of at least partially disabling at least a portion of said arc fault detector for a finite period of time to permit a user to use an electrical device exhibiting arcing, and enabling said disabled portion of said arc fault detector after use of the electrical device exhibiting arcing has been discontinued.

47. The device according to claim 35, further comprising a fault detector capable of detecting faults other than arc faults, and activating said trigger circuit when a fault other than an arc fault is detected.

48. The device according to claim 47, wherein said fault detector comprises a ground fault circuit interrupter that detects the occurrence of a ground fault and generates a trigger signal in response to the detection of the ground fault that activates said trigger circuit.

49. The device according to claim 47, wherein said fault detector comprises an immersion detection circuit interrupter capable of detecting the occurrence of an immersion fault and generating a trigger signal in response to the detection of the immersion fault that activates said trigger circuit.

50. The device according to claim 47, wherein said fault detector comprises an appliance leakage circuit interrupter capable of detecting the occurrence of an appliance leakage fault and generating a trigger signal in response to the detection of the appliance leakage fault that activates said trigger circuit.

51. A method for detecting arc faults using a circuit interrupting device comprising:

sensing current flowing through the device;

generating a high frequency signal corresponding to a level of high frequency current flowing through the device;

generating an AC line frequency signal corresponding to a level of AC line frequency current flowing through the device;

generating an arc fault trigger signal in response to at least one of a detected arc fault within said high frequency signal and a detected arc fault within said AC line frequency signal; and

disconnecting a source of electrical power to a load side of the device in response to said arc fault trigger signal.

52. The method according to claim 51, further comprising inhibiting the disconnecting of the source of electrical power to the load side of the device for a finite period of time to permit use of an electrical device exhibiting arcing connected to the circuit interrupting device, and uninhibiting the disconnection of the source of electrical power to the load side of the device after use of said electrical device has been discontinued.

53. The method according to claim 51, further comprising:

detecting ground faults from said sensed current; and

generating a trigger signal when a ground fault is detected, wherein the source of electrical power to the load side of the device is disconnected in response to said trigger signal.

54. The method according to claim 51, further comprising:

detecting immersion detection faults from said sensed current; and

generating a trigger signal when an immersion detection fault is detected, wherein the source of electrical power to the load side of the device is disconnected in response to said trigger signal.

55. The method according to claim 51, further comprising:

detecting appliance leakage faults from said sensed current; and

generating a trigger signal when an appliance leakage fault is detected, wherein the source of electrical power to the load side of the device is disconnected in response to said trigger signal.