Protection system for devices connected to an alternating current electrical power supply

• US 6,525,914 B1
• Filed: 01/03/2000
• Issued: 02/25/2003
• Est. Priority Date: 05/26/1999
• Status: Expired due to Term

• Current Assignee: Technology Research Group LLC (Southwire Company)
• Original Assignee: Technology Research Corporation (Southwire Company)
• Inventors: Legatti, Raymond H.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/476,562
• Time in Patent Office: 1,149 Days
• Field of Search: 361/45, 361/42, 361/93.1, 361/115
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0023 sensing non electrical parameters, e.g. by optical, pneumatic, thermal or sonic sensors
• CPC Class Codes: H02H 3/14 responsive to occurrence of voltage on parts normally at earth potential monitoring earth connection H02H5/105
• 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
• CPC Class Codes: H02H 5/043 the temperature dependent resistor being disposed parallel to a heating wire, e.g. in a heating blanket

Abstract

A protective arrangement for an electrical device energized from an alternating current power supply which de-energizes the electrical device when undesirable conditions, develop within the electrical device. The protective arrangement, when provided for an electrical device having protection for undesirable leakage currents in the power cord supplying to electrical device, utilizes the same circuit interrupting device to de-energize the electrical device upon the occurrence of an undesirable condition, other than a leakage current, within the device, or upon the occurrence of an undesirable leakage current in the power cord supplying the electrical device.

Claims

1. A protective arrangement for an electrical device energized from an alternating current power source through a power cord including at least a pair of power leads and a third conductive lead comprising:

a circuit interrupter which disconnects the electrical device from the power source upon the flow of a current of a magnitude greater than a predetermined magnitude in the third conductive lead, a sensor system in said electrical device for sensing an undesirable condition in said electrical device, the detection of an undesirable condition in the electrical device by said sensor system causing a current to flow through the third conductive lead, such that when said current flow is greater than said predetermined magnitude, the electrical device will be disconnected from the power source.

2. The protection arrangement for an electrical device of claim 1, wherein said sensor system upon the detection of an undesirable condition causes an electrical connection to be established between one of said power leads and said third conductive lead to cause a current of a magnitude greater than said predetermined magnitude to flow in said third conductive lead, whereby said circuit interrupter will disconnect the electrical device from the power source.

3. The protection arrangement for an electrical device of claim 1, wherein said sensor system includes a pressure sensing device.

4. The protection arrangement for an electrical device of claim 1, wherein said sensor system includes a flame sensing device.

5. The protection arrangement for an electrical device of claim 4, wherein said sensor system includes an electrical switch actuated by the exposure of a heat sensitive material to flame in the protected electrical device.

6. The protection arrangement for an electrical device of claim 4, wherein said sensor system includes a photoelectric cell for detecting the presence of flame in the protected electrical device.

7. The protection arrangement for an electrical device of claim 1, wherein said sensor system includes a light emitting diode and a light sensitive semiconductor switch which detect a change in the light transmission between said light emitting diode and said light sensitive semiconductor switch to cause a current flow, greater than said predetermined magnitude, through said third conductive lead.

8. The protection arrangement for an electrical device of claim 1, wherein said sensor system includes a heat sensing device.

9. The protection arrangement for an electrical device of claim 1, wherein said third conductive lead is also the ground lead for the electrical device.

10. The protection arrangement for an electrical device of claim 1, wherein said sensor system includes an electrical connection between a conductive portion of the electric device which is not electrically connected to either of the pair of power leads, and the third conductive lead.

11. The protection arrangement for an electrical device of claim 1, wherein said third conductive lead is a sensor lead, such that the flow of a leakage current therein, greater than said predetermined magnitude, from a power lead, will cause the electrical device to be disconnected from the power source.

12. The protection arrangement for an electrical device of claim 1, wherein said circuit interrupter and said third conductive lead provide a leakage current protective device for said power cord.

13. The protective arrangement for an electrical device of claim 1, wherein the electrical device includes a solenoid which is energized a predetermined period of time after the electrical device is energized, to cause actuation of a mechanism, and opening of a switch to de-energize the device, and failure of said mechanism to be actuated, and of said switch to be opened, upon energization of said solenoid causing said protective arrangement to disconnect the electrical device from the power source.

14. The protective arrangement for an electrical device of claim 13, wherein detection of an undesirable condition in the electrical device, in less than said predetermined period of time, will disconnect the electrical device from the power source, such that said solenoid will not be energized.

15. The protective arrangement for an electrical device of claim 13, wherein the electrical device is a pop-up toaster, and energization of said solenoid releases a pop-up mechanism to raise a toast carriage, and to open said switch, failure of said pop-up mechanism to raise the toast carriage and to open said switch upon energization of said solenoid causing said protective arrangement to disconnect the electrical device from the power source.

16. The protective arrangement for an electrical device of claim 15, wherein detection of an undesirable condition in the pop-up toaster, in less than said predetermined period of time after the pop-up toaster is energized, will disconnect the pop-up toaster and prevent energization of said solenoid and release of said pop-up mechanism.

17. A protective arrangement for an electrical device energized from an alternating current power source through a power cord including at least a pair of power leads and a third conductive lead comprising:

a circuit interrupter which disconnects the electrical device from the power source upon the flow of a current of a magnitude greater than a predetermined magnitude in the third conductive lead, said third conductive lead being connected to a conductive portion of the electrical device, which is electrically insulated from the pair of power leads, such that the flow of an electrical current from a power lead to the conductive portion of the electrical device will flow through the third conductive lead and will disconnect the electrical device from the power source upon the flow of a current greater than said predetermined magnitude.

18. A protective arrangement for an electrical device energized from an alternating current power source through a power cord including at least a pair of power leads and a third conductive lead electrically insulated from each other by electrical insulation, comprising:

a circuit interrupter which disconnects the electrical device from the power source upon the flow of a current of a magnitude greater than a predetermined magnitude in the third conductive lead, a sensor system in said electrical device for sensing an undesirable condition in said electrical device, the detection of an undesirable condition in the electrical device by said sensor system causing a current to flow through said third conductive lead, the failure of the electrical insulation between the power leads and said third conductive lead resulting in a leakage current flow in said third conductive lead, such that when said current flow in said third conductive lead is greater than said predetermined magnitude, the electrical device will be disconnected from the power source.

19. The protection arrangement for an electrical device of claim 18, wherein said sensor system upon the detection of an undesirable condition causes an electrical connection to be established between one of said power leads and said third conductive lead to cause a current of a magnitude greater than said predetermined magnitude to flow in said third conductive lead, whereby said circuit interrupter will disconnect the electrical device from the power source.

20. The protection arrangement for an electrical device of claim 18, wherein said sensor system includes a pressure sensing device.

21. The protection arrangement for an electrical device of claim 18, wherein said sensor system includes a flame sensing device.

22. The protection arrangement for an electrical device of claim 21, wherein said sensor system includes an electrical switch actuated by the exposure of a heat sensitive material to flame in the protected electrical device.

23. The protection arrangement for an electrical device of claim 21, wherein said sensor system includes a photoelectric cell for detecting the presence of flame in the protected electrical device.

24. The protection arrangement for an electrical device of claim 18, wherein said sensor system includes a light emitting diode and a light sensitive semiconductor switch which detect a change in the light transmission between said light emitting diode and said light sensitive semiconductor switch to cause a current flow, greater than said predetermined magnitude, through said third conductive lead.

25. The protection arrangement for an electrical device of claim 18, wherein said sensor system includes a heat sensing device.

26. The protection arrangement for an electrical device of claim 18, wherein said third conductive lead is also the ground lead for the electrical device.

27. The protection arrangement for an electrical device of claim 18, wherein said sensor system includes an electrical connection between a conductive portion of the electric device which is not electrically connected to either of the pair of power leads, and the third conductive lead.

28. The protection arrangement for an electrical device of claim 18, wherein said third conductive lead is a sensor lead, such that the flow of a leakage current therein, greater than said predetermined magnitude, from a power lead, will cause the electrical device to be disconnected from the power source.

29. A protective arrangement for an electrical device energized from an alternating current power source through a power cord including at least a pair of power leads and a third conductive lead electrically insulated from each other by electrical insulation, comprising:

a circuit interrupter which disconnects the electrical device from the power source upon the flow of a current of a magnitude greater than a predetermined magnitude in the third conductive lead, said third conductive lead being connected to a conductive portion of the electrical device, which is electrically insulated from the pair of power leads, such that the flow of an electrical current from a power lead to the conductive portion of the electrical device will flow through the third conductive lead, as will a leakage current resulting from the failure of the electrical insulation between the power leads and the third conductive lead, whereby the electrical device will be disconnected from the power source upon the flow of a current greater than said predetermined magnitude.