Claims
- 1. A sensor comprising:
a cable comprising: a first conductor, a second conductor and an extruded semi-conductive layer is adapted to change resistance in response to a change in pressure or temperature and is located between said first and second conductors; a signal generator connected to the first conductor; and a signal detector connected to the second conductor, wherein the first and second conductors are adapted to pass a signal from the signal generator to the signal detector where the magnitude of the signal is dependent on the resistance of the semi-conductive layer and wherein the cable is hermetically seated.
- 2. The sensor of claim 1, wherein the first and second conductors are coaxial.
- 3. The sensor of claim 2, wherein the semi-conductive layer is in contact with both the first and second conductors.
- 4. The sensor of claim 1, wherein the semi-conductive layer includes carbon.
- 5. The sensor of claim 1, wherein the resistance of the semi-conductive layer changes in response to a change in temperature.
- 6. The sensor of claim 1, further including a protective jacket.
- 7. The sensor of claim 1, wherein the first and second conductors are permitted to touch in the absence of a fault condition.
- 8. The sensor of claim 1, wherein fault detection is integral.
- 9. The sensor of claim 1, further including a separate fault detection device.
- 10. The sensor of claim 9, further comprising a timing device.
- 11. The sensor of claim 6, wherein the first and second conductors are copper; the semi-conductive layer is low density polyethylene doped with lampblack; and the a said protective jacket is low density polyethylene.
- 12. A device comprising a first conductor coaxial with a second conductor; and an extruded semi-conductive layer located between said first and second conductors, wherein the first and second conductors are adapted to pass a signal where the magnitude of the signal is dependent on the resistance of the semi-conductive layer and wherein the first conductor, the second conductor and the semi-conductive layer are hermetically sealed.
- 13. The device of claim 12, wherein the semi-conductive layer includes a thermoplastic.
- 14. The device of claim 13, wherein the semi-conductive layer includes a conductive material.
- 15. The device of claim 13, wherein the conductive material is carbon.
- 16. The device of claim 13, further including a protective jacket.
- 17. The device of claim, wherein the first and second conductors are permitted to touch in the absence of a fault condition.
- 18. A method of sensing changes in ambient conditions, comprising:
passing electricity from a signal generator, by way of a first conductor, through an extruded semi-conductive layer with a resistance to a signal detector by way of a second conductor; and measuring a change in the resistance in response to a change in pressure or temperature, wherein the first conductor, the second conductor and the semi-conductive layer are hermetically sealed.
RELATED APPLICATIONS
[0001] This application is a continuation of Ser. No. 10/306,498, filed Nov. 27, 2002 now U.S. Pat. No. 6,724,195, issued Apr. 20, 2004, which is a continuation-in-part of U.S. application Ser. No. 10/113,301 filed on Mar. 29, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60404019 |
Sep 2002 |
US |
Continuations (1)
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Number |
Date |
Country |
Parent |
10306498 |
Nov 2002 |
US |
Child |
10827586 |
Apr 2004 |
US |
Continuation in Parts (1)
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Number |
Date |
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Parent |
10113301 |
Mar 2002 |
US |
Child |
10306498 |
Nov 2002 |
US |