Patent EP0028142A1 successfully refreshed from Google Patents.
EP0028142A1
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Fault detecting sensor and method of detecting faults therewith
Assignee: Raychem Corp
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Filing: 1980-10-24
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Granted: —
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Expires: 2000-10-24
Abstract
Abstract This invention relates to sensors for detecting a fault condition, e.g. excessive temperature or leakage of fluid, in a large apparatus, and to methods of using such devices. The novel sensors comprise a conductor, an element composed of a conductive polymer whose resistivity increases sharply when a fault condition occurs, and a dielectric element which separates the conductor and conductive polymer element so that they form an electrical capacitor. The sensor is in the form of a sheet or cable whose capacitance is periodically measured. When a fault condition occurs, the conductive polymer element increases sharply in resistance in the region of the fault and reduces the capacitance of the sensor, thus signalling the occurrence (and preferably also the location) of the fault. Figure 1 shows a typical sensor in the form of a cable comprising a central conductor 10, a dielectric layer 12, a PTC layer 14 and on outer protective layer 16. The invention is particularly useful for detecting localised overheating, e.g. in dryers for agricultural products, or leakage of a fluid, e.g. from a conduit.
Inventors
- 👤 Michael Allan Lutz
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 19:19
CPC Classifications
G; G01; G01M; G01M3/00; G01M3/02; G01M3/04; G01M3/16; G01M3/165; G01K; G01K3/00; G01M3/002; G01M3/042; G01M3/045
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
66 words
A fault-dectecting sensor comprising (a) a first electrical conductor, (b) a dielectric element, and (c) a second electrical conductor arranged to form a capacitor, the second electrical conductor comprising a solid conductive polymer composition composed of solid polymer and electrically conductive particles dispersed in said polymer, which composition increases in resistivity when the sensor is exposed to increased temperature, thereby producing a measurable change in capacitance.
Claim 2
Dependent Claim
66 words
A fault-dectecting sensor comprising (a) a first electrical conductor, (b) a dielectric element, and (c) a second electrical conductor arranged to form a capacitor, the second electrical conductor comprising a solid conductive polymer composition composed of solid polymer and electrically conductive particles dispersed in said polymer, which composition increases in resistivity when the sensor is exposed to increased temperature, thereby producing a measurable change in capacitance.
Claim 3
Dependent Claim
64 words
A fault-dectecting sensor comprising (a) a first electrical conductor, (b) a dielectric element, and (c) a second electrical conductor arranged to form a capacitor, the second electrical conductor comprising a solid conductive polymer composition composed of solid polymer and electrically conductive particles dispersed in said polymer, which composition increases in resistivity when exposed to the fault condition, thereby producing a measurable change in capacitance.
Claim 4
Dependent Claim
64 words
A fault-dectecting sensor comprising (a) a first electrical conductor, (b) a dielectric element, and (c) a second electrical conductor arranged to form a capacitor, the second electrical conductor comprising a solid conductive polymer composition composed of solid polymer and electrically conductive particles dispersed in said polymer, which composition increases in resistivity when exposed to the fault condition, thereby producing a measurable change in capacitance.
Claim 5
Dependent Claim
28 words
A sensor according to Claim 1 or 2, wherein the conductive polymer composition is selected to undergo a substantial increase in resistivity at a predetermined threshold switching temperature.
Claim 6
Dependent Claim
31 words
A sensor according to claim 1, 2 or 3, wherein the dielectric element (b) surrounds the first electrical conductor (a), and the second electrical conductor (c) surrounds the dielectric element (b).
Claim 7
Dependent Claim
26 words
A sensor according to Claim 1, 2 or 3, wherein the first electrical conductor, the dielectric element, and the second electrical conductor are elongated flat layers.
Claim 8
Dependent Claim
34 words
A sensor according to any one of claims 1 to 5 having an outer protective layer which is composed of a dielectric material and which is in physical contact with said conductive polymer composition.
Claim 9
Dependent Claim
46 words
A sensor according to any of the preceding claims, wherein the conductive polymer composition and any outer layers thereon are permeable to a fluid which is present in the fault condition and which, when absorbed by the conductive polymer composition, causes it to increase in resistivity.
Claim 10
Dependent Claim
33 words
A sensor according to any of claims 1 to 6, wherein the arrangemment is such that, in use, the conductive polymer composition is physically stretched by the fault condition thereby increasing its resistivity.
Claim 11
Dependent Claim
26 words
A sensor according to any one of the preceding claims, wherein the conductive polymer composition exhibits PTC behavior with a switching temperature between 50 and 150°C.
Claim 12
Dependent Claim
47 words
A sensor according to any one of the preceding claims, wherein the sensor is in the form of a cable of substantially constant cross-section, whereby the location of the fault can be determined by comparing the respective capacitances of the cable before and during a fault condition.
Claim 13
Dependent Claim
27 words
A sensor according to claim 1 substantially as hereinbefore described with reference to any of Figures 1 to 4 of the accompanying drawings, or in Example 1.
Claim 14
Independent Claim
43 words
A method of monitoring a location to detect the occurrence of a fault condition therein, which method is characterised by providing the location with a fault-detecting sensor as claimed in any of the preceding claims, and periodically measuring the capacitance of the sensor.
Claim 15
Dependent Claim
27 words
A method according to claim 11 substantially as hereinbefore described with reference to Figure 1, 2, 3 or 4 of the accompanying drawings or in Example 1.
References Cited (Backward Citations)
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