Leakage current detection and interruption circuit powered by leakage current

• US 8,659,857 B2
• Filed: 07/23/2009
• Issued: 02/25/2014
• Est. Priority Date: 07/24/2008
• Status: Expired due to Fees

• Current Assignee: Technology Research Group LLC (Southwire Company)
• Original Assignee: Technology Research Corporation (Southwire Company)
• Inventors: Gandolfi, Paul R.
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): WILLOUGHBY, TERRENCE RONIQUE
• Application Number:
  US12/460,695
• Publication Number:
  US 20100020452A1
• Time in Patent Office: 1,678 Days
• Field of Search: None
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• 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

Abstract

A circuit is disclosed for disconnecting a power source upon the detection of a leakage current from one of a first and a second wire connected to the power source. A sensing conductor is located adjacent to one of the first and second wires for sensing a leakage current from one of the first and second wires. A disconnect switch is interposed within the first and second wires connected to the power source. A disconnect switch control circuit is connected to the sensing conductor for opening the disconnect switch upon the presence of a leakage current from the sensing conductor. The disconnect switch control circuit operates solely from the leakage current from the sensing conductor.

Claims

1. A circuit for disconnecting a power source upon the detection of a leakage current from one of a first and a second wire connected to the power source, comprising:

a sensing conductor located adjacent to one of the first and second wires for sensing a leakage current from one of the first and second wires;

a disconnect switch interposed within the first and second wires connected to the power source;

said disconnect switch having a disconnect switch solenoid coil for opening said disconnect switch;

a threshold conduction device being conductive upon a threshold voltage applied to the threshold conduction device;

a connector connecting said disconnect switch solenoid coil in series with said threshold conduction device between one of the first and second wires and said sensing conductor; and

a threshold voltage generator comprising a capacitor connected in series with a diode between said sensing conductor and one of the first and second wires for charging said capacitor for generating said threshold voltage for said threshold conduction device upon a leakage current flow between said sensing conductor and one of the first and second wires and through said threshold voltage generator.

2. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said sensing conductor comprises a first and a second shield sensing conductor located about the first and second wires.

3. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said sensing conductor comprises a shield sensing conductor located about both of the first and second wires.

4. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said disconnect switch includes a normally open solenoid operated switch;

a mechanical latch mechanism for maintaining said disconnect switch in a closed condition and

said disconnect switch solenoid coil operating a plunger for disengaging said mechanical latch mechanism for opening said disconnect switch.

5. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said threshold conduction device includes a thyristor.

6. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said threshold conduction device includes a silicon, control rectifier (SCR).

7. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said threshold conduction device includes a silicon control rectifier (SCR) with a Zener diode connected to a gate of said silicon control rectifier (SCR).

8. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said threshold conduction device is a Diode For Alternating Current (DIAC).

9. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said threshold conduction device is a Silicon Diode For Alternating Current (SIDAC).

10. A circuit for disconnecting a power source upon the detection of a leakage current from one of a first and a second wire connected to the power source, comprising:

a sensing conductor located adjacent to one of the first and second wires for sensing a leakage current from one of the first and second wires;

a disconnect switch interposed within the first and second wires connected to the power source;

said disconnect switch having a disconnect switch solenoid coil for opening said disconnect switch;

a divider circuit interconnected between the first and second wires for providing a divider node;

a threshold conduction device being conductive upon a threshold voltage applied to the threshold conduction device;

a connector connecting said disconnect switch solenoid coil in series with said threshold conduction device between said divider node and said sensing conductor; and

a capacitor connected between said divider node and said sensing conductor to provide said threshold voltage to said threshold conduction device upon a leakage current flow between said sensing conductor and one of the first and second wires.

11. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said divider circuit includes a diode divider circuit.

12. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 11, wherein said divider circuit includes a resistive divider circuit.

13. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said divider circuit provides a voltage node.

14. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said capacitor is connected between said divider node and said sensing conductor and in parallel with said threshold conduction device.

15. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said threshold conduction device includes a silicon control rectifier (SCR).

16. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said threshold conduction device is a Diode For Alternating Current (DIAC).

17. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said threshold conduction device is a Silicon Diode For Alternating Current (SIDAC).

18. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said threshold conduction device comprises a thyristor connected in series with said disconnect switch solenoid coil between and said divider node and said sensing conductor;

and

a breakdown voltage conduction device connected for actuating said thyristor upon said capacitor providing a breakdown voltage to said breakdown voltage conduction device.

19. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 10, wherein said threshold conduction device comprises a thyristor connected in series with said disconnect switch solenoid coil and said divider node and said sensing conductor;

and

a Zener diode connected to a gate of said thyristor for actuating said thyristor upon said capacitor providing a breakdown voltage to said Zener diode.

20. A circuit for disconnecting a power source upon the detection of a leakage current from one of a first and a second wire connected to the power source, comprising:

a sensing conductor located adjacent to one of the first and second wires for sensing a leakage current from one of the first and second wires;

a disconnect switch interposed within the first and second wires connected to the power source;

said disconnect switch having a disconnect switch solenoid coil for opening said disconnect switch;

a threshold conduction device being conductive upon a threshold voltage applied to the threshold conduction device;

a connector connecting said disconnect switch solenoid coil in series with said threshold conduction device between said divider node and said sensing conductor; and

a capacitor connected between said sensing conductor and one of the first and second wires for charging said capacitor with a leakage current flow between said sensing conductor and one of the first and second wires to provide said threshold voltage generator to said threshold conduction device.

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 sensing conductor located adjacent to the wire for sensing a leakage current from the wire;

a disconnect switch interposed within the wire connected to the power source; and

a disconnect switch control circuit comprising a capacitor connected to said sensing conductor for opening said disconnect switch upon said capacitor accumulating a predetermined amount of the leakage current from said sensing conductor.