US3737557A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric cables with ethylene-propylene insulation
Assignee: Balfour Beatty PLC
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Filing: 1972-06-27
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Granted: 1973-06-05
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Expires: 1992-06-27
Abstract
Abstract An electric cable comprises at least one insulated conductor enclosed in a sheath of a polymeric composition which comprises a polymerized propylene sequence and a propylene/ethylene copolymer sequence, has a melt index (230*C; 2.16 kgms) of 0.01 to 0.5, preferably 0.025 to 0.25 and an ethylene content in the range 1030 percent by weight, preferably at least 15 percent by weight. The conductor can be insulated with the same polymeric composition as is used for the sheath. The cable may also include a dielectric screen material which is the polymeric composition containing 20-40 percent by weight of carbon black.
Inventors
- 👤 S Verne
- 👤 T Heggs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:31
CPC Classifications
H; H01; H01B; H01B9/00; H01B7/00; H01B7/02; H01B7/0208; H01B7/17; H01B7/18; H01B7/28; H01B7/282; H01B7/285; H01B9/02; H01B9/027; Y; Y02; Y02A; Y02A30/00; Y02A30/14
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
52 words
An electric cable as claimed in claim 1, wherein the crystalline polymeric composition of the sheath has a melt flow index of between 0.025 and 0.25, an ethylene content of at least 15 percent by weight and consists of one sequence of homopolymerized propylene and one sequence of propylene copolymerized with ethylene.
Claim 2
Dependent Claim
103 words
An electric cable as claimed in claim 1, wherein the insulating covering of the conductor or of at least one of the conductors is formed of a crystalline polymeric composition comprising at least one sequence of either homopolymerized propylene or of propylene copolymerized with up to 10 percent by weight of the composition of at least one other olefine monomer which may be or may include ethylene, and at least a further sequence of propylene copolymerized with ethylene wherein said composition contains between 10 and 30 percent by weight of polymerized ethylene and has a melt flow index of between 0.01 and 0.5.
Claim 3
Dependent Claim
120 words
An electric cable as claimed in claim 1, wherein the or each insulated conductor has a conductor and/or dielectric screen formed of a composition comprising a. a crystalline polymeric composition having at least one sequence of either homopolymerized propylene or of propylene copolymerized with up to 10 percent by weight of the polymeric composition of at least one other olefine monomer which may be or may include ethylene, and at least a further sequence of propylene copolymerized with ethylene wherein said polymeric composition contains between 25 and 30 percent by weight of polymerized ethylene and has a melt flow index of between 0.01 and 0.5 and b. 20-40 percent by weight, based on the total composition, of conductive carbon black.
Claim 4
Dependent Claim
48 words
An electric cable as claimed in claim 1, wherein a plurality of plastics insulated conductors are enclosed within the sheath and the interstices between the insulated conductors and between them and the sheath from end to end of the cable length are filled with a water impermeable medium.
Claim 5
Dependent Claim
20 words
An electric cable as claimed in claim 5, wherein the plastics insulating covering of each conductor is of cellular form.
Claim 6
Dependent Claim
35 words
An electric cable as claimed in claim 1, wherein the insulating covering of the or each conductor is compacted powdered mineral insulation and a metal sheath underlies the sheath formed of the crystalline polymeric composition.
Claim 7
Dependent Claim
98 words
An electric cable as claimed in claim 3, for installation in a system in which during operation of the cable the insulating covering of the or each conductor is subjected to a pressure above atmospheric by a cable gas which has access to one or more surfaces of the dielectric, wherein the insulating covering of the or each conductor is of solid form and is impregnated with a cable gas to an extent such that until the cable is put into service, at least the major part of the solid insulating covering remains fully impregnated with the gas.
References Cited (Backward Citations)
US3569610A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |