Over-temperature sense and locate device
AssigneeRaychem Corporation
InventorMichael A. Lutz
Life of this patent
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Abstract
The invention is an over-temperature sensor and locator utilizing a temperature sensitive cable comprising (1) an electrical conductor, (2) a dielectric, and (3) a solid, conductive polymeric, positive temperature coefficient of resistance composition. An over-temperature condition at any point along the cable is detected by a drop in the capacitance of the cable, as measured from one end of the cable. The location of the over-temperature point on the cable is determined by comparing the reduced capacitance from the control end to the over-temperature point with the capacitance of the full cable length.
Claims20
An over-temperature sense and locate device comprising:
- a. an electrical conductor;
- b. a dielectric material in contact with said electrical conductor;
- c. a solid conductive PTCR polymeric composition in contact with said dielectric material and separated from said electrical conductor by said dielectric material, said solid PTCR conductive polymeric composition being normally conductive and being capable of a massive increase in resistivity at a predetermined elevated temperature at any location along said solid PTCR conductive polymeric composition where said predetermined elevated temperature occurs;
- and
- d. means for sensing said location of elevated temperature, said means electrically connected to said electrical conductor and said solid conductive PTCR polymeric composition, said means comprising means for measuring and comparing the electrical capacitances between said electrical conductor and said solid PTCR conductive polymeric composition before and during exposure to said elevated temperature, the ratio of said capacitance determining the location of said elevated temperature condition.
A temperature sensitive cable comprising:
- a. an electrical conductor;
- b. a dielectric material in contact with said electrical conductor;
- and
- c. a solid conductive PTCR polymeric composition in contact with said dielectric material and separated from said electrical conductor by said dielectric material, said solid PTCR conductive polymeric composition being normally conductive and being capable of a massive increase in resistivity at a predetermined elevated temperature at any location along said solid PTCR polymeric composition where said predetermined elevated temperature occurs, wherein when said solid PTCR conductive polymeric composition and said electrical conductor are connected to a capacitance measuring device, the capacitance between said electrical conductor and said solid PTCR conductive polymeric composition may be measured before and during exposure to the elevated temperature, and the ratio of said capacitances will determine the location of predetermined elevated temperature.
Dependencies are inferred from the claim text.