Leakage current detection and interruption circuit with improved shield

• US 8,064,174 B2
• Filed: 08/11/2009
• Issued: 11/22/2011
• Est. Priority Date: 01/04/2005
• Status: Expired due to Fees

• Current Assignee: Technology Research Group LLC (Southwire Company)
• Original Assignee: Technology Research Corporation (Southwire Company)
• Inventors: Gandolfi, Paul R., Brugner, Frank S. Jr., Williams, Thomas S.
• Primary Examiner(s): PATEL, DHARTI HARIDAS
• Application Number:
  US12/462,883
• Publication Number:
  US 20090303642A1
• Time in Patent Office: 833 Days
• Field of Search: 361/42
• 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 3/33 using summation current transformers H02H3/347 takes precedence

Abstract

A circuit is disclosed for disconnecting a power source upon the detection of a leakage current comprising a power cable having an insulated first and a second wire. The power cable has a conductive shield surrounding the first and second wires with a drain wire electrically contacting the conductive shield. A disconnect switch is interposed between the power source and the power cable. A primary circuit controls the disconnect switch. A secondary circuit is connected to the drain wire for sensing a leakage current between the conductive shield and one of the first and second wires. An optical switch interconnects the primary circuit and the secondary circuit for opening the disconnect switch upon the secondary circuit sensing a leakage current.

Claims

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

a leakage current circuit comprising a disconnect switch;

a power cable connected to the power source though said disconnect switch;

said power cable consisting of;

a. a first insulated wire and a second insulated wire;

b. an insulated ground wire;

c. a conductive shield surrounding all of said first and second insulated wires and said insulated ground wire;

d. a drain wire having a first and a second portion with said first portion of said drain wire being in contact with said conductive shield; and

e. an outer insulating layer disposed about said conductive shield and said first portion of said drain wire; and

a conductor connecting said second portion of said drain wire to said leakage current circuit for opening said disconnect switch upon said leakage current circuit sensing a leakage current between said conductive shield and one of said first and second insulated wires and said insulated ground wire to disconnect said power cable from the power source.

2. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said conductive shield is an insulating polymeric sheet with a metallic coating.

3. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said conductive shield is an insulating polymeric sheet with an aluminum coating.

4. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said conductive shield is a metallic foil.

5. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said conductive shield is an aluminum foil.

6. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 1, wherein said conductive shield is an organic conductive polymeric material.

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

a leakage current circuit comprising a disconnect switch;

a power cable connected to the power source though said disconnect switch;

said power cable consisting of;

a. a first insulated wire and a second insulated wire;

b. an insulated ground wire;

c. a conductive shield consisting of an insulating polymeric sheet with a conductive coating surrounding all of said first and second insulated wires and said insulated ground wire;

d. a drain wire having a first and a second portion with said first portion of said drain wire being in contact with said conductive coating of said conductive shield; and

d. an outer insulating layer disposed about said conductive shield and said first portion of said drain wire; and

a conductor connecting said second portion of said drain wire to said leakage current circuit for opening said disconnect switch upon said leakage current circuit sensing a leakage current between said conductive coating and one of said first and second insulated wires and said insulated ground wire to disconnect said power cable from the power source.

8. A circuit for disconnecting a power source upon the detection of a leakage current as set forth in claim 7, wherein said conductive coating of said conductive shield is an aluminum coating.

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

a leakage current circuit comprising a disconnect switch;

a power cable connected to the power source though said disconnect switch;

said power cable consisting of;

a. a first insulated wire and a second insulated wire;

b. a conductive shield surrounding both of said first and second insulated wires;

c. a drain wire having a first and a second portion with said first portion of said drain wire being in contact with said conductive shield; and

d. an outer insulating layer disposed about said conductive shield and said first portion of said drain wire; and

a conductor connecting said second portion of said drain wire to said leakage current circuit for opening said disconnect switch upon said leakage current circuit sensing a leakage current between said conductive shield and one of said first and second insulated wires to disconnect said power cable from the power source.

10. An improved power cable for use with a leakage current detection and interruption circuit for disconnecting a power source upon the detection of a leakage current within the improved power cable, the improved power cable consisting of:

a. an first insulated wire and a second insulated wire;

b. an insulated ground wire;

c. a conductive shield consisting of an insulating polymeric sheet with a conductive coating surrounding all of said first and second insulated wires and said insulated ground wire;

d. a drain wire having a first and a second portion with said first portion of said drain wire being in contact with said conductive coating of said conductive shield; and

e. an outer insulating layer disposed about said conductive shield and said first portion of said drain wire; and

said second portion of said drain wire being connected to the leakage current detection and interruption circuit for disconnecting the power source upon the detection of a leakage current within the improved power cable between said conductive coating and one of said first and second insulated wires and said insulated ground wire.

11. An improved power cable for use with a leakage current detection and interruption circuit for disconnecting a power source upon the detection of a leakage current within the improved power cable, the improved power cable consisting of:

a. an first insulated wire and a second insulated wire;

b. a conductive shield consisting of an insulating polymeric sheet with a conductive coating surrounding all of said first and second insulated wires;

c a drain wire having a first and a second portion with said first portion of said drain wire being in contact with said conductive coating of said conductive shield; and

d. an outer insulating layer disposed about said conductive shield and said first portion of said drain wire; and

said second portion of said drain wire being connected to the leakage current detection and interruption circuit for disconnecting the power source upon the detection of a leakage current within the improved power cable between said conductive coating and one of said first and second insulated wires.