Portable circuit interrupter shutoff testing device and method

• US 7,173,428 B2
• Filed: 11/12/2002
• Issued: 02/06/2007
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Maxim D. Hurwicz
• Original Assignee: Maxim D. Hurwicz
• Inventors: Hurwicz, Maxim D.
• Primary Examiner(s): Lee; Diane
• Assistant Examiner(s): Teresinski; John
• Application Number:
  US10/293,524
• Publication Number:
  US 20030090271A1
• Time in Patent Office: 1,547 Days
• Field of Search: 324/424, 324/536, 324/555, 361/42, 361/43, 393/424
• US Class Current: 324/424
• CPC Class Codes: G01R 31/3272 Apparatus, systems or circuits therefor G01R31/3275 takes precedence
• CPC Class Codes: G01R 31/3333 Apparatus, systems or circuits therefor

Abstract

A portable circuit interrupter shutoff testing device and method, including a high current switch controlled by a timing circuit that allows current to flow through the switch and a small series resistance (in order to trip the instantaneous-trip function of the interrupter, as opposed to the overload-trip) for a short time period relative to the sine wave of the electrical power. A button activates the timing circuit which in turn activates the switch and current flows limited by the internal resistor of the device. By limiting the on time of the device to one of a few half cycles, the user can test if the circuit interrupter responds as quickly as specified by the manufacturer. A method includes receiving a stimulation indication, and selectively connecting an electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

Claims

1. A tester for a circuit-interrupter, wherein the circuit-interrupter includes an overload-trip function and an instantaneous-trip function, the tester comprising:

an electrical plug having a first external electrical connector and a second external electrical connector;

a control circuit that outputs a control signal;

an electronic switch selectively enabled by the control signal; and

an electrical load connected to the electronic switch such that the electronic switch connects the electrical load to the first external electrical connector and the second external electrical connector as controlled by the control signal, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

2. The tester of claim 1, wherein the control signal enables the electronic switch to conduct limited to a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

3. The tester of claim 2, wherein the pre-specified maximum trip time of the instantaneous-trip function is three cycles of AC power.

4. The tester of claim 3, wherein the electronic switch is enabled to conduct for a time no greater than about one-half cycle of AC power.

5. The tester of claim 1, wherein the electronic switch is enabled to conduct for a time no greater than about one-half cycle of AC power.

6. The tester of claim 1, wherein the electrical load acts as a fuse that opens as a result of failure of the electronic switch to stop conduction.

7. The tester of claim 1, wherein the control circuit includes a programmable controller.

8. The tester of claim 1, further comprising a ground fault tester circuit that comprises a small current load selectively coupled between the first external electrical connector of the plug and a third external electrical connector of the plug.

9. The tester of claim 1, further comprising a manually activated switch coupled to the control circuit, wherein the switch initiates output of the control signal.

10. A tester for a circuit-interrupter, wherein the circuit-interrupter includes an overload-trip function and an instantaneous-trip function, the tester comprising:

an electrical plug having a first external electrical connector and a second external electrical connector;

a control circuit that outputs a control signal;

an electronic switch selectively enabled by the control signal; and

an electrical load connected to the electronic switch such that the electronic switch connects the electrical load to the first external electrical connector and the second external electrical connector as controlled by the control signal, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter;

wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the control circuit provides an enabling control signal pulse to the SCR at a point in time when an electrical load on the SCR is about 30 volts.

11. The tester of claim 10, wherein the electronic switch is enabled to conduct for a time no greater than about one-half cycle of AC power.

12. A method of testing a circuit-interrupter, wherein the circuit-interrupter includes an overload-trip function and an instantaneous-trip function, the method comprising:

providing a portable testing device that includes an electrical plug having a first external electrical connector and a second external electrical connector;

connecting the first and second external electrical connectors to a socket that is wired to a load side of the circuit interrupter;

receiving a stimulation indication; and

selectively connecting an electrical load to first and second external electrical connectors connected to the wires connected to the load side of the circuit interrupter based on the reception of the stimulation indication, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

13. The method of claim 12, wherein the selectively connecting includes connecting the electrical load to the circuit-interrupter for a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

14. The method of claim 13, wherein the pre-specified maximum trip time of the instantaneous-trip function is three cycles of AC power.

15. The method of claim 14, wherein the selectively connecting includes connecting the electrical load to the circuit-interrupter for a time no greater than about one-half cycle of AC power.

16. The method of claim 12, further comprising:

stopping electrical conduction in the electrical load as a result of a failure of the selectively connecting to stop conduction.

17. A method of testing a circuit-interrupter, wherein the circuit-interrupter includes an overload-trip function and an instantaneous-trip function, the method comprising:

providing an electrical plug having a first external electrical connector and a second external electrical connector that are connected by wires to the circuit interrupter;

receiving a stimulation indication; and

selectively connecting an electrical load to the first and second external electrical connectors that are connected to the wires connected to the circuit interrupter based on the reception of the stimulation indication, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter, wherein the selectively connecting includes providing an enabling control signal pulse to an SCR at a point in time when an electrical load on the SCR is about 30 volts.

18. A tester for a circuit-interrupter, wherein the circuit-interrupter includes an instantaneous-trip function, the tester comprising:

a portable testing device that includes an electrical plug having a first external electrical connector and a second external electrical connector, and

means for selectively connecting and disconnecting an electrical load to the first external electrical connector and the second external electrical connector, both being connected by wires that are connected to the load side of the circuit interrupter, and that are intended to be protected by the circuit interrupter, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

19. The tester of claim 18, wherein the means for selectively connecting includes means for connecting the electrical load to the circuit-interrupter for a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

20. The tester of claim 19, wherein the pre-specified maximum trip time of the instantaneous-trip function is about three cycles of AC power, and the electronic switch is enabled to conduct for a time no greater than about one-half cycle of AC power.

21. A tester for a circuit-interrupter, the tester comprising:

an electrical connection having a first external electrical connector and a second external electrical connector;

a control circuit that outputs a control signal;

a first electronic switch selectively enabled by the control signal such that the electronic switch conducts an overcurrent between the first external electrical connector and the second external electrical connector and then stops conducting at a point in time before the circuit-interrupter opens its circuit.

22. The tester of claim 21, wherein the circuit-interrupter includes an instantaneous-trip function, and wherein the electronic switch conducts an overcurrent between the first external electrical connector and the second external electrical connector and then stops conducting at a point in time before the instantaneous-trip function of the circuit-interrupter opens its circuit.

23. The tester of claim 22, wherein the circuit-interrupter also includes an overload-trip function, and the tester trips the instantaneous-trip function of the circuit-interrupter but not the overload-trip function of the circuit-interrupter.

24. The tester of claim 21, wherein the electronic switch is enabled to conduct for a time no greater than about one-half cycle of AC power.

25. The tester of claim 21, wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the control circuit provides an enabling control signal pulse to the SCR at a point in time after a zero-crossing.

26. The tester of claim 21, further comprising a ground fault tester circuit that comprises a small current load selectively coupled between the first external electrical connector of the plug and a third external electrical connector of the electrical connection.

27. The tester of claim 21, wherein the overcurrent is limited by a resistance in the tester of about 0.15 ohms.

28. The tester of claim 21, wherein the overload current is about ten times a continuous current rating of the circuit interrupter.

29. An apparatus comprising:

an electrical connector adapted to be connected to a load-side circuit of a circuit interrupter;

a control circuit;

an electronic switch; and

an electrical load selectively connectable to the electrical connector by the electronic switch as controlled by the control circuit, wherein the electrical load causes an instantaneous trip current to be drawn through load-side circuit of the circuit interrupter, wherein the instantaneous trip current is sufficient to meet an instantaneous trip current specification of the circuit interrupter.

30. The apparatus of claim 29, wherein the control circuit enables the electronic switch to conduct limited to a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

31. The apparatus of claim 29, wherein the control circuit enables the electronic switch to conduct limited to a time no greater than three cycles of AC power.

32. The apparatus of claim 29, wherein the control circuit enables the electronic switch to conduct limited to a time no greater about one-half cycle of AC power.

33. The apparatus of claim 29, wherein the electrical load acts as a fuse that opens as a result of failure of the electronic switch to stop conduction.

34. The apparatus of claim 29, wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the control circuit provides an enabling control signal pulse to the SCR at a point in time shortly after a zero-crossing, in order that the SCR is reliably and consistently triggered.

35. A device for testing an instantaneous-trip function of a circuit interrupter having a designated fault current rating which is supplied with a certain line voltage, with the instantaneous-trip function being responsive to an overload condition on the load-side of the circuit interrupter where the line voltage and the resistance of the load-side circuit of the circuit interrupter affects the quantity of current available for tripping the circuit interrupter, the tester comprising:

connectors adapted to connect with the load-side circuit of the circuit interrupter;

a control circuit which issues a control signal;

an electronic switch enabled by the control signal; and

an electrical load connected to and disconnected to from the load-side circuit via the selective enabling of the electronic switch producing a fault current sufficient to test the instantaneous-trip function subject to the resistance of the load-side resistance.

36. The device of claim 35, wherein the control signal enables the electronic switch to conduct limited to a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

37. The device of claim 35, wherein the control signal enables the electronic switch to conduct limited to a time no greater than three cycles of AC power.

38. The device of claim 35, wherein the control signal enables the electronic switch to conduct limited to a time no greater about one-half cycle of AC power.

39. The device of claim 35, wherein the electrical load acts as a fuse that opens as a result of failure of the electronic switch to stop conduction.

40. The device of claim 35, wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the control circuit provides an enabling control signal pulse to the SCR at a point in time after a zero-crossing.

41. A method of testing the instantaneous-trip function of a circuit interrupter, the method comprising:

providing a portable testing device that includes an electrical plug having a first external electrical connector and a second external electrical connector adapted to be plugged into a socket wired to a load side of the circuit interrupter, and

receiving a stimulation indication; and

selectively connecting and disconnecting an electrical load to and from the load-side of the circuit interrupter conditional on a receiving of the stimulation indication, wherein the electrical load, when connected, supplies sufficient current to test the instantaneous-trip function of the circuit interrupter.

42. The method of claim 41, wherein the control signal enables the electronic switch to conduct limited to a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

43. The method of claim 41, wherein the control signal enables the electronic switch to conduct limited to a time no greater than three cycles of AC power.

44. The method of claim 41, wherein the control signal enables the electronic switch to conduct limited to a time no greater about one-half cycle of AC power.

45. The method of claim 41, wherein the electrical load acts as a fuse that opens as a result of failure of the electronic switch to stop conduction.

46. The method of claim 41, wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the control circuit provides an enabling control signal pulse to the SCR at a point in time after a zero-crossing.

47. A tester for testing a circuit interrupter having a line-side, a load-side, a designated instantaneous-tripping current and a designated clearing time, the tester comprising:

a first electrical connector adapted to connect to the load-side circuit'"'"'s hot conductor of the circuit interrupter;

a second electrical connector adapted to connect to the load-side circuit'"'"'s neutral conductor of the circuit interrupter;

a control circuit that outputs a control signal for a predetermined time period based on the designated clearing time; and

an electronic switch which when enabled by the control signal during the predetermined time period conducts a current proportional to the resistance of the circuit of the load-side of the circuit interrupter plus the resistance of the tester'"'"'s circuit and which when disabled by the control signal after the time period'"'"'s end effectively discontinues the current.

48. The tester of claim 47, wherein the control circuit outputs a control signal for a time no greater than the designated clearing time.

49. The tester of claim 47, wherein the control circuit outputs a control signal for a time shorter than the designated clearing time.

50. The tester of claim 47, wherein the tester includes a resistance to limit the current drawn through the load-side circuit of the circuit breaker.

51. The tester of claim 47, wherein the tester includes a resistance which acts as a fuse that opens as a result of failure of the electronic switch to discontinue conduction.

52. The tester of claim 47, wherein a third electrical connector is selectively connected to the load-side circuit of the circuit interrupter.

53. A tester for testing an instantaneous-trip function of a circuit interrupter, the circuit interrupter having a load-side circuit, the tester comprising:

a first external electrical connector for connecting to the load-side circuit'"'"'s hot conductor of the circuit interrupter and a second electrical connector for connecting to the load-side circuit'"'"'s neutral conductor of the circuit interrupter;

means for initiating, maintaining for a predetermined time, and then terminating a control signal; and

an electronic switch responsive to the control signal such that, when the switch is conducting, a completed circuit communicating a fault current proportional to the resistance of the circuit is created.

54. The tester of claim 53, wherein the control signal enables the electronic switch to conduct limited to a time no greater than a pre-specified maximum trip time of the instantaneous-trip function.

55. The tester of claim 53, wherein the control circuit outputs a control signal for a time shorter than a pre-specified maximum trip time of the instantaneous-trip function.

56. The tester of claim 53, wherein the tester includes a resistance to limit the fault current of the circuit.

57. The tester of claim 53, wherein the tester includes a resistance which acts as a fuse.

58. The tester of claim 53, wherein the control signal enables the electronic switch to conduct limited to a time no greater than about one-half cycle of AC power.

59. The tester of claim 53, wherein the electronic switch includes a silicon-controlled rectifier (SCR), and the means for initiating the control signal provides an enabling control signal pulse to the SCR at a point in time shortly after a zero-crossing, in order that the SCR is reliably and consistently triggered during each one of a predetermined limited number of half cycles.

60. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during one half cycle of AC power.

61. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during two half cycles of AC power.

62. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during three half cycles of AC power.

63. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during four half cycles of AC power.

64. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during five half cycles of AC power.

65. The tester of claim 59, wherein the control signal enables the electronic switch to conduct a current sufficient to trigger the instantaneous-trip function of the circuit-interrupter, but only during six half cycles of AC power.

66. The tester of claim 53, further comprising a ground fault current generator that provides a ground fault current sufficient to trigger the ground fault trip function of the circuit-interrupter, selectively coupled only during a predetermined limited number of half cycles of AC power.

67. The tester of claim 53, further comprising a overload current generator that provides a overload current sufficient to trigger the overload trip function of the circuit-interrupter, selectively coupled only during a predetermined limited number of half cycles of AC power.

68. The tester of claim 67, wherein the overload current generator provides the overload current, but only during about 100 seconds of AC power.