Capacitive temperature sensing for electrical conductor

Patent metadata

Field	Value
Publication number	US-10458860-B2
Application number	US-201415522337-A
Country	US
Kind code	B2
Filing date	Oct 30, 2014
Priority date	Oct 30, 2014
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

Provided is a system for directly sensing, measuring, or monitoring the temperature of an electrical conductor ( 31 ) of a power cable ( 10 ). A temperature sensitive capacitor ( 21 C) is disposed in direct thermal contact with the electrical conductor ( 31 ). The temperature sensitive capacitor ( 21 C) includes a dielectric material that has a dielectric constant variable with the temperature of the electrical conductor ( 31 ). The temperature of the electrical conductor ( 31 ) can be sensed, measured, or monitored by measuring the capacitance of the temperature sensitive capacitor ( 21 C).

First claim

What is claimed is:

1. A temperature-sensing apparatus for sensing a temperature of an electrical conductor enclosed in at least a (semi)conductive layer, the apparatus comprising:
a temperature sensitive capacitor, the temperature sensitive capacitor comprising a capacitor body and at least two electrodes arranged in an interdigitated configuration and supported by the capacitor body, at least a portion of the capacitor body comprising one or more temperature-sensitive dielectric materials that have a dielectric constant varying with temperature, and the electrodes being disposed in proximity to the temperature-sensitive dielectric materials,
wherein the capacitor body is disposed in thermal contact with the electrical conductor, and the capacitance of the temperature sensitive capacitor is variable with the temperature of the electrical conductor,
wherein the capacitor body has a ring-shape structure with an inner surface and an outer surface, and
wherein the capacitor body surrounds the electrical conductor, and the capacitor body comprises an elastic material that is flexible and deformable to have the inner surface thereof compress against and be in thermal contact with a circumferential surface of the electrical conductor, and the electrodes are disposed on the outer surface of the capacitor body or embedded into the capacitor body.

2. The apparatus of claim 1 , wherein the capacitor body further includes a thermal-conductive portion in direct contact with the electrical conductor.

3. The apparatus of claim 1 , wherein the electrodes include first and second electrodes that are arranged in an interdigitated comb configuration.

4. The apparatus of claim 1 , wherein the capacitor is disposed between the electrical conductor and the (semi)conductive layer, and is enclosed by the (semi)conductive layer.

5. The apparatus of claim 1 , wherein the temperature-sensitive dielectric materials include one or more synthetic polymers.

6. The apparatus of claim 5 , wherein the synthetic polymers include at least one of nylon-6 and nylon-6,6.

7. The apparatus of claim 1 , wherein the one or more temperature-sensitive dielectric materials include particles of a ferroelectric ceramic material that are dispersed in a polymer matrix.

8. The apparatus of claim 7 , wherein the polymer matrix comprises polymers selected from the group consisting of silicones, epoxies, ethylene-propylene-diene rubbers, polyolefins, polyurethanes, epichlorohydrins, fluoroelastomers, polyolefins, polyamides, and polyimides.

9. The apparatus of claim 7 , wherein the ferroelectric ceramic material comprises between about 15 weight % and about 90 weight % of the capacitive sensing composition.

10. The apparatus of claim 7 , wherein the ferroelectric ceramic material is chosen from the group consisting of doped BaTiO 3 , BaSnTiO 3 , BaHfTiO 3 , BaSrTiO 3 , BaZrTiO 3 , SrTiO 3 , BaFe 12 O 19 , Pb[Zr x Ti (1−x) ]O 3 , and x[Pb(Mg 1/3 Nb 2/3 )O 3 ]-(1−x)[PbTiO 3 ], and combinations and mixtures thereof.

11. The apparatus of claim 1 , further comprising an inductor that is electrically connected to the interdigitated capacitor to form a passive LC circuit.

12. The apparatus of claim 11 , further comprising a transceiver unit electromagnetically coupled to the passive LC circuit, and the transceiver unit being configured to send out a signal representing a change of the capacitance of the interdigitated capacitor upon a change of the temperature of the electrical conductor.

13. An electrical cable assembly comprising:
an electrical conductor enclosed in a (semi)conductive layer; and
one or more of the temperature-sensing apparatuses of claim 1 ,
wherein the temperature-sensing apparatuses are distributed along the electrical conductor and configured to sense a temperature distribution of the electrical conductor.

Assignees

• 3M Innovative Properties Co

Inventors

• Wen Zhiguo
• Kim Jaewon
• Johnson Justin M
• Yu Xeutao
• Mahoney David V
• Benson Michael D
• Sebesta Christopher D
• Kang Myungchan

Classifications

• G01K13/00

  Thermometers specially adapted for specific purposes · CPC title

• H01B7/324

  comprising temperature sensing means · CPC title

• H01G7/04

  having a dielectric selected for the variation of its permittivity with applied temperature · CPC title

• G01K7/343 Primary

  the dielectric constant of which is temperature dependant · CPC title

• G01K7/34

  using capacitative elements (capacitors per se H01G) · CPC title