Leakage current detection and interruption circuit

• US 20060146456A1
• Filed: 12/30/2005
• Published: 07/06/2006
• Est. Priority Date: 01/04/2005
• Status: Active Grant

• Current Assignee: Technology Research Group LLC (Southwire Company)
• Original Assignee: Technology Research Corporation (Southwire Company)
• Inventors: Williams, Thomas S.
• Granted Patent: US 7,751,161 B2
• Time in Patent Office: Days
• US Class Current: 361/42
• CPC Class Codes: H01H 73/44 reset by push-button, pull-knob or slide
• CPC Class Codes: H01H 83/02 operated by earth fault currents H01H83/14 takes precedence
• CPC Class Codes: H02H 1/0038 concerning the connection of the detecting means, e.g. for reducing their number
• CPC Class Codes: H02H 1/0069 by means of light or heat rays
• CPC Class Codes: H02H 3/044 Checking correct functioning of protective arrangements, e.g. by simulating a fault for differential current circuit breakers H02H3/335
• CPC Class Codes: H02H 3/16 responsive to fault current to earth, frame or mass with balanced or differential arrangement H02H3/26 ; monitoring earth connection H02H5/105
• CPC Class Codes: H02H 3/32 involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence
• CPC Class Codes: H02H 5/10 responsive to mechanical injury, e.g. rupture of line, breakage of earth connection

Abstract

A circuit is disclosed for disconnecting a power source upon the detection of a leakage. The circuit comprises a disconnect switch for disconnecting the power source. A primary circuit controls the disconnect switch. A secondary circuit senses a leakage current. An optical switch interconnects the primary circuit and the secondary circuit for opening the disconnect switch upon the secondary circuit sensing a leakage current. The circuit is suitable for use as a leakage current detection and interruption circuit for completely electrically disconnecting and isolating the power source and the primary circuit from the secondary circuit.

Claims

1. A circuit for disconnecting a power source upon the detection of a leakage current, comprising:

a disconnect switch connected to the power source;

a primary circuit for controlling said disconnect switch;

a secondary circuit for sensing a leakage current; and

an optical switch interconnecting said primary circuit and said secondary circuit for opening said disconnect switch upon said secondary circuit sensing a leakage current.

2. A circuit as set forth in claim 1, wherein said disconnect switch includes a solenoid operated switch.

3. A circuit as set forth in claim 1, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a latch for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

4. A circuit as set forth in claim 1, wherein said secondary circuit includes a light emitting device for sensing a leakage current.

5. A circuit as set forth in claim 1, wherein said secondary circuit includes sensing conductor;

and

a light emitting device for sensing a leakage current from said sensing conductor.

6. A circuit as set forth in claim 1, wherein said secondary circuit includes a shield sensing conductor;

and

a light emitting device for sensing a leakage current from said shield sensing conductor.

7. A circuit as set forth in claim 1, wherein said secondary circuit includes a voltage divider circuit for powering said secondary circuit;

and

a light emitting device connected to said voltage divider circuit for sensing a leakage current.

8. A circuit as set forth in claim 1, wherein said optical switch includes a light emitting device optically coupled to a photoconductive switch for completely electrically isolating the power source upon the opening of said disconnect switch.

9. A circuit as set forth in claim 1, wherein said optical switch includes a light emitting device electrically connected to said secondary circuit for sensing a leakage current;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

10. A circuit as set forth in claim 1, wherein said optical switch includes an optocoupler switch having a light emitting device electrically connected to said secondary circuit for sensing a leakage current;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said optocoupler switch having a light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

11. A circuit for disconnecting a power source upon the detection of a leakage current, comprising:

a disconnect switch connected to the power source;

a primary circuit located on a primary side of said disconnect switch for controlling said disconnect switch;

a secondary circuit located on a secondary of said disconnect switch for sensing a leakage current; and

an optical switch interconnecting said primary circuit and said secondary circuit for opening said disconnect switch upon said secondary circuit sensing a leakage current.

12. A circuit as set forth in claim 11, wherein said disconnect switch includes a solenoid operated switch.

13. A circuit as set forth in claim 11, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a latch for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

14. A circuit as set forth in claim 11, wherein said secondary circuit includes a light emitting device for sensing for sensing a leakage current.

15. A circuit as set forth in claim 11, wherein said secondary circuit includes sensing conductor;

and

a light emitting device for sensing for sensing a leakage current from said sensing conductor.

16. A circuit as set forth in claim 11, wherein said secondary circuit includes a shield sensing conductor;

and

a light emitting device for sensing a leakage current from said shield sensing conductor.

17. A circuit as set forth in claim 11, wherein said secondary circuit includes a voltage divider circuit for powering said secondary circuit;

and

a light emitting device connected to said voltage divider circuit for sensing a leakage current.

18. A circuit as set forth in claim 11, wherein said optical switch includes a light emitting device optically coupled to a photoconductive switch for completely electrically isolating the power source upon the opening of said disconnect switch.

19. A circuit as set forth in claim 11, wherein said optical switch includes a light emitting device electrically connected to said secondary circuit for sensing a leakage current;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

20. A circuit as set forth in claim 11, wherein said optical switch includes an optocoupler switch having a light emitting device electrically connected to said secondary circuit for sensing a leakage current;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said optocoupler switch having a light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

21. A circuit for disconnecting a power source upon the detection of a leakage current from a wire connected to the power source, comprising:

a disconnect switch interposed within the wire connecting to the power source;

a primary circuit located on a primary side of said disconnect switch for controlling said disconnect switch;

a secondary circuit located on a secondary of said disconnect switch for sensing a leakage current from the wire; and

an optical switch interconnecting said primary circuit and said secondary circuit for opening said disconnect switch upon said secondary circuit sensing a leakage current from the wire.

22. A circuit as set forth in claim 21, wherein said disconnect switch includes a solenoid operated switch.

23. A circuit as set forth in claim 21, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a latch for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

24. A circuit as set forth in claim 21, wherein said secondary circuit includes a light emitting device for sensing for sensing a leakage current from the wire.

25. A circuit as set forth in claim 21, wherein said secondary circuit includes sensing conductor located adjacent to the wire connected to the power source;

and

a light emitting device for sensing for sensing a leakage current between the wire and said sensing conductor.

26. A circuit as set forth in claim 21, wherein said secondary circuit includes a shield sensing conductor located about the wire connected to the power source;

and

a light emitting device for sensing a leakage current between the wire and said shield sensing conductor.

27. A circuit as set forth in claim 21, wherein said secondary circuit includes a shield sensing conductor located about the wire connected to the power source;

a voltage divider circuit interconnecting said shield sensing conductor and the wire; and

a light emitting device connected to said voltage divider circuit for sensing a leakage current between the wire and said shield sensing conductor.

28. A circuit as set forth in claim 21, wherein said optical switch includes a light emitting device optically coupled to a photoconductive switch for completely electrically isolating the power source upon the opening of said disconnect switch.

29. A circuit as set forth in claim 21, wherein said optical switch includes a light emitting device electrically connected to said secondary circuit for sensing a leakage current from the wire;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

30. A circuit as set forth in claim 21, wherein said optical switch includes an optocoupler switch having a light emitting device electrically connected to said secondary circuit for sensing a leakage current from the wire;

a photoconductive switch connected to said primary circuit for controlling said disconnect switch; and

said optocoupler switch having a light emitting device being optically coupled to a photoconductive switch for electrically isolating said primary circuit from secondary circuit.

31. A leakage current detection and interruption circuit for disconnecting a power source upon the detection of a leakage current from a wire interconnecting the power source with a load, comprising:

a disconnect switch interposed within the wire for disconnecting the power source from the load;

a primary circuit located between said disconnect switch and the power source for controlling said disconnect switch;

a secondary circuit located between said disconnect switch and the load for sensing a leakage current from the wire; and

an optical switch having a photoconductive switch electrically connected to said primary circuit and a light emitting device electrically connected to said secondary circuit; and

said light emitting device being optically coupled to said photoconductive switch for opening said disconnect switch upon said secondary circuit sensing a leakage current from the wire for completely electrically disconnecting the power source from the load and completely electrically disconnecting said primary circuit and said secondary circuit.

32. A leakage current detection and interruption circuit as set forth in claim 31, wherein said disconnect switch includes a solenoid operated switch.

33. A leakage current detection and interruption circuit as set forth in claim 31, wherein said disconnect switch includes a normally closed solenoid operated switch.

34. A leakage current detection and interruption circuit as set forth in claim 31, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a latch for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

35. A leakage current detection and interruption circuit as set forth in claim 31, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a mechanical latch mechanism for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

36. A leakage current detection and interruption circuit as set forth in claim 31, wherein said primary circuit includes a silicon controlled rectifier for opening said disconnect switch upon said secondary circuit sensing a leakage current from the wire.

37. A leakage current detection and interruption circuit as set forth in claim 31, wherein said secondary circuit includes a light emitting device for sensing for sensing a leakage current from the wire.

38. A leakage current detection and interruption circuit as set forth in claim 31, wherein said secondary circuit includes a shield sensing conductor located about the wire interconnecting the power source with the load;

and

a light emitting device for sensing for sensing a leakage current between the wire and said shield sensing conductor.

39. A leakage current detection and interruption circuit as set forth in claim 31, wherein said secondary circuit includes a shield sensing conductor located about the wire interconnecting the power source with the load;

a voltage divider circuit interconnecting said shield sensing conductor and the wire; and

a light emitting device connected to said voltage divider circuit for sensing for sensing a leakage current between the wire and said shield sensing conductor.

40. A leakage current detection and interruption circuit as set forth in claim 31, wherein said photoconductive switch of said optical switch comprises a photo transistor and said light emitting device comprises a light emitting diode.

41. A leakage current detection and interruption circuit for disconnecting a power source from a load interconnected by a first and a second wire having a first and a second shield, respectively, upon the detection of a leakage current between the wire and the shielded of one of said first and second wires, comprising:

a disconnect switch interposed within the first and second wires for disconnecting the power source from the load;

a primary circuit located between said disconnect switch and the power source for controlling said disconnect switch;

a secondary circuit located between said disconnect switch and the load for sensing a leakage current between the wire and the shielded of one of said first and second wires; and

an optical switch interconnecting said primary circuit and said secondary circuit for opening said disconnect switch upon said secondary circuit sensing a leakage current from the wire for completely electrically disconnecting the power source from the load and completely electrically disconnecting said primary circuit and said secondary circuit.

42. A leakage current detection and interruption circuit as set forth in claim 41, wherein said disconnect switch includes a solenoid operated switch.

43. A leakage current detection and interruption circuit as set forth in claim 41, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a latch for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

44. A leakage current detection and interruption circuit as set forth in claim 41, wherein said disconnect switch includes a normally closed solenoid operated switch;

and

a mechanical latch mechanism for maintaining said disconnect switch in an open condition upon said secondary circuit sensing a leakage current from the wire.

45. A leakage current detection and interruption circuit as set forth in claim 41, wherein said primary circuit includes a silicon controlled rectifier for opening said disconnect switch upon said secondary circuit sensing a leakage current from the wire.

46. A leakage current detection and interruption circuit as set forth in claim 41, wherein said secondary circuit includes a light emitting device for sensing for sensing a leakage current from the wire.

47. A leakage current detection and interruption circuit as set forth in claim 41, wherein said secondary circuit includes a voltage divider circuit interconnecting said shield sensing conductor and the wire;

and

a light emitting device connected to said voltage divider circuit for sensing for sensing a leakage current between the wire and said shield sensing conductor.

48. A leakage current detection and interruption circuit as set forth in claim 41, wherein said photoconductive switch of said optical switch comprises a photo transistor and said light emitting device comprises a light emitting diode.