Temperature sensing cable device and method of making same
First Claim
1. A method of remote overheat detection of an area for use with an elongate temperature sensing cable formed of i) a polymeric composition having a negative temperature coefficient characteristic when above an anomaly temperature and ii) at least two spaced-apart electrical conductors electrically interconnected by means of the composition, the method comprising the steps of:
- extending a predefined length of the electrical temperature sensing cable in said area;
applying an electric field to at least a portion of the composition in the area;
detecting tunneling conduction current flow through the composition in a presence of the overheat condition above said anomaly temperature; and
,generating current flow is detected.
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Accused Products
Abstract
A continuous temperature sensing cable formed of a polymer containing conductive and semi-conductive fillers such as polyethylene with carbon black, powdered metals and metal oxides controlled within the range of from about eight percent (8%) to about fifteen percent (15%). The composition is extruded with a pair of elongated substantially parallel conductors which are spaced apart along the longitudinal length of the cable. The conductors are single endedly connected to a control/alarm device for monitoring the continuous length of the temperature sensing cable. The control/alarm device may be a time domain reflectometer TDR for accurate determination of localized discontinuities caused by high temperatures along the length of the temperature sensing cable. Alternatively, a critical voltage may be applied single-endedly to the conductors and serially connected to an audible alarm to detect tunneling conduction when operated at a temperature near the melt temperature of the composition.
46 Citations
22 Claims
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1. A method of remote overheat detection of an area for use with an elongate temperature sensing cable formed of i) a polymeric composition having a negative temperature coefficient characteristic when above an anomaly temperature and ii) at least two spaced-apart electrical conductors electrically interconnected by means of the composition, the method comprising the steps of:
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extending a predefined length of the electrical temperature sensing cable in said area; applying an electric field to at least a portion of the composition in the area; detecting tunneling conduction current flow through the composition in a presence of the overheat condition above said anomaly temperature; and
,generating current flow is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of remote overheat detection of an area for use with an elongate temperature sensing cable formed of a composition having at least one polymeric component and an amount of electrically conductive particles therein to promote a negative temperature coefficient characteristic of the composition when above an anomaly temperature and in a presence of an electric field sufficient to promote tunneling conduction current in said composition, the method comprising the steps of:
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extending a predefined length of the electrical temperature sensing cable into said area; applying said electric field to at least a portion of the composition in the area; detecting the tunneling conduction current flow through the composition in a presence of the overheat condition above said anomaly temperature; and
,generating an alarm signal when the tunneling conduction current flow is detected. - View Dependent Claims (9, 10, 11, 12, 13)
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14. An overheat alarm system for detecting an overheat condition in an area, the system comprising:
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an elongate temperature sensing cable extended over a first length in said area, the cable being formed of a composition having at least one polymeric component and an amount of electrically conductive particles therein to promote a negative temperature coefficient characteristic of the composition when above an anomaly temperature and in the presence of an electric field sufficient to promote tunneling conduction current in said composition; at least two electrical conductor means for conducting electrical current, the at least two electrical conductor means being electrically interconnected by said composition; supply means for applying said electric field through the at least two electrical conductor means to at least a portion of the composition in the area; tunneling current detecting means for detecting a tunneling conduction current flow through the composition in a presence of the overheat condition above said anomaly temperature in said area; and
,alarm generating means for generating an alarm signal when the tunneling conduction current flow is detected. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An overheat alarm system comprising:
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a temperature sensing element having a negative temperature coefficient of electrical resistance above an anomaly temperature, the element comprising; a composition exhibiting reversible electrical behavior, the composition containing at least one polymeric component and an amount of blended electrically conductive carbon black and zinc oxide particles therein to promote a reversible negative temperature coefficient characteristic of the composition when above the anomaly temperature and in a presence of an electric field sufficient to promote conduction in said composition; and
,at least two electrical conduction means, electrically interconnected through the composition, for conducting electric current in said temperature sensing element; supply means for applying said electric field to said at least two electrical conduction means; tunneling current detecting means for detecting a tunneling conduction current flow through the composition in a presence of the overheat condition above said anomaly temperature; and
,alarm generating means for generating an alarm signal when the tunneling conduction current flow is detected. - View Dependent Claims (21, 22)
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Specification