US4687882A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Surge attenuating cable
Assignee: Ontario Power Generation Inc
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Filing: 1986-04-28
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Granted: 1987-08-18
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Expires: 2006-04-28
Abstract
Abstract In a shielded power cable of the type comprising inner and outer conductors separated by cable insulation defining a displacement current path between the conductors for high frequency currents, the cable insulation incorporates one or more coaxial layers of semiconductive material consisting of cable insulation material loaded with a conductive filler, such as carbon fibres or spheres. The semiconductive layer is designed to maximize high frequency losses thereby to facilitate attenuation of high voltage surges caused by lightning or by switching.
Inventors
- 👤 Gregory C. Stone
- 👤 Steven A. Boggs
- 👤 Jean-Marie Braun
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:26
CPC Classifications
H; H01; H01B; H01B9/00; H01B9/02; H01B9/027; Y; Y10; Y10S; Y10S174/00; Y10S174/13; Y10S174/26; Y10S174/27; Y10S174/28
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
112 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising at least two coaxial layers defining a displacement current path between the conductors for high frequency currents, namely an inner semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length of cable, and an outer insulating layer presenting a capacitance C per unit length of cable, wherein the conductivity, relative permittivity, and thickness of said inner semiconductive layer are such that the power loss per unit length of cable is maximized with respect to the conductance G 1 at least over the frequency range 0.1 MHz-50 MHz.
Claim 2
Dependent Claim
112 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising at least two coaxial layers defining a displacement current path between the conductors for high frequency currents, namely an inner semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length of cable, and an outer insulating layer presenting a capacitance C per unit length of cable, wherein the conductivity, relative permittivity, and thickness of said inner semiconductive layer are such that the power loss per unit length of cable is maximized with respect to the conductance G 1 at least over the frequency range 0.1 MHz-50 MHz.
Claim 3
Dependent Claim
147 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising at least three coaxial layers defining a displacement current path between the conductors for high frequency currents, namely the inner semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length of cable, an outer semiconductive layer presenting a conductance G 2 and a capacitance C 2 per unit length of cable, and an intermediate insulating layer presenting a capacitance C per unit length of cable, wherein the conductivities, relative permittivities, and the thicknesses of said semiconductive layers are such that the power loss per unit length of cable is maximized with respect to both said conductance G 1 of the inner semiconductive layer and said conductance G 2 of the outer semiconductive layer at least over the frequency range 0.1 MHz-50 MHz.
Claim 4
Dependent Claim
147 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising at least three coaxial layers defining a displacement current path between the conductors for high frequency currents, namely the inner semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length of cable, an outer semiconductive layer presenting a conductance G 2 and a capacitance C 2 per unit length of cable, and an intermediate insulating layer presenting a capacitance C per unit length of cable, wherein the conductivities, relative permittivities, and the thicknesses of said semiconductive layers are such that the power loss per unit length of cable is maximized with respect to both said conductance G 1 of the inner semiconductive layer and said conductance G 2 of the outer semiconductive layer at least over the frequency range 0.1 MHz-50 MHz.
Claim 5
Dependent Claim
39 words
A shielded power cable according to claim 2, wherein the material of the semiconductive layers has a conductivity which remains substantially constant and a relative permittivity which does not exceed about 12 over the frequency range 0.1 MHz-50 MHz.
Claim 6
Dependent Claim
65 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system which provides a displacement current path between the conductors for high frequency currents, the cable insulation system incorporating at least one semiconductive layer arranged coaxially therewith having a conductivity which remains substantially constant and a relative permittivity which does not exceed about 12, over the frequency range 0.1 MHz-50 MHz.
Claim 7
Dependent Claim
65 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system which provides a displacement current path between the conductors for high frequency currents, the cable insulation system incorporating at least one semiconductive layer arranged coaxially therewith having a conductivity which remains substantially constant and a relative permittivity which does not exceed about 12, over the frequency range 0.1 MHz-50 MHz.
Claim 8
Dependent Claim
25 words
A shielded power cable according to claim 4, wherein the cable insulation system incorporates a second semiconductive layer of the same material as the first.
Claim 9
Dependent Claim
100 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising three coaxial layers defining a displacement current path between the conductors for high frequency currents, namely an inner semiconductive layer, an outer semiconductive layer, and an intermediate insulating layer, wherein the materials of said semiconductive layers is an extrudable polymeric material loaded with a low structure particulate conductive filler, and wherein the material of said layers has a conductivity which remains substantially constant, and a relative permittivity which does not exceed about 12, over the frequency range 0.1 MHz-50 MHz.
Claim 10
Dependent Claim
100 words
A shielded power cable comprising inner and outer conductors separated by a cable insulation system, the cable insulation system comprising three coaxial layers defining a displacement current path between the conductors for high frequency currents, namely an inner semiconductive layer, an outer semiconductive layer, and an intermediate insulating layer, wherein the materials of said semiconductive layers is an extrudable polymeric material loaded with a low structure particulate conductive filler, and wherein the material of said layers has a conductivity which remains substantially constant, and a relative permittivity which does not exceed about 12, over the frequency range 0.1 MHz-50 MHz.
Claim 11
Dependent Claim
28 words
A shielded power cable according to claim 6, wherein the polymeric material is a material selected from the group consisting of a polyolefin and a blend of rubbers.
Claim 12
Dependent Claim
16 words
A shielded power cable according to claim 7, wherein the conductive filler consists of carbon fibres.
Claim 13
Dependent Claim
16 words
A shielded power cable according to claim 7, wherein the conductive filler consists of carbon spheres.
Claim 14
Dependent Claim
14 words
A shielded power cable according to claim 7, wherein the conductive filler is metallic.
Claim 15
Dependent Claim
124 words
An electrical power transmission system comprising inner and outer coaxial conductors separated by an insulation system, the insulation system extending longitudinally with respect to the conductors and comprising at least two coaxial regions defining a displacement current path between the conductors for high frequency currents, namely an inner region consisting of a semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length, and an outer non-conductive region presenting a capacitance C per unit length, characterized in this that the conductivity, relative permittivity and thickness of said semiconductive layer are such that the power loss per unit length of the transmission system is maximized with respect to the conductance G 1 at least over the frequency range 0.1 MHz-50 MHz.
Claim 16
Dependent Claim
124 words
An electrical power transmission system comprising inner and outer coaxial conductors separated by an insulation system, the insulation system extending longitudinally with respect to the conductors and comprising at least two coaxial regions defining a displacement current path between the conductors for high frequency currents, namely an inner region consisting of a semiconductive layer presenting a conductance G 1 and a capacitance C 1 per unit length, and an outer non-conductive region presenting a capacitance C per unit length, characterized in this that the conductivity, relative permittivity and thickness of said semiconductive layer are such that the power loss per unit length of the transmission system is maximized with respect to the conductance G 1 at least over the frequency range 0.1 MHz-50 MHz.
Claim 17
Dependent Claim
55 words
An electrical power transmission system according to claim 11, wherein the material of said semiconductor layer is an extrudable polymeric material loaded with a low structure particulate conductive filler, said material having a conductivity which remains substantially constant, and a relative permittivity which does not exceed about 12, over the frequency range 0.1 MHz-50 MHz.
Claim 18
Dependent Claim
29 words
An electrical power transmission system according to claim 12, wherein the polymeric material is a material selected from the group consisting of a polyolefin and a blend of rubbers.
Claim 19
Dependent Claim
17 words
An electrical power transmission system according to claim 13, wherein the conductive filler consists of carbon fibres.
Claim 20
Dependent Claim
17 words
An electrical power transmission system according to claim 13, wherein the conductive filler consists of carbon spheres.
Claim 21
Dependent Claim
15 words
An electrical power transmission system according to claim 13, wherein the conductive filler is metallic.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-17 | 1991-02-16 | 1991-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-17 | 1995-02-16 | 1995-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-17 | 1999-02-16 | 1999-08-18 | $7700.00 | Window Closed / Lapsed |