US3749812A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High voltage cable
Assignee: Individual
•
Filing: 1972-04-03
•
Granted: 1973-07-31
•
Expires: 1992-04-03
Abstract
Abstract In a fluid-filled cable for service at 200 kV and upwards a lowviscosity naphthene-free mineral oil is used to impregante a paper/polypropylene/paper laminate. The polypropylene is selected for low solubility in the oil, and the paper has a density of 0.85Mg/m3 or less, an impermeability of at least 10,000 Gurley seconds, and a thickness, at least in the inner high-stress zone of the dielectric, of 50 micrometers or less, preferably 25 micrometers.
Inventors
- 👤 E Reynolds
- 👤 D Edwards
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:18
CPC Classifications
H; H01; H01B; H01B9/00; H01B9/06; H01B9/0611; H01B13/00; H01B13/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
16 words
A cable as claimed in claim 1 wherein said fluid is a mixed paraffinic/aromatic mineral oil.
Claim 2
Dependent Claim
20 words
A cable as claimed in claim 2 wherein said oil has a viscosity less than 25 centistokes at 20* C.
Claim 3
Dependent Claim
21 words
A cable as claimed in claim 3 wherein said viscosity at 20* C is in the range 12.5 - 15 centistokes.
Claim 4
Dependent Claim
17 words
A cable as claimed in claim 1 wherein said paper layers have a thickness of 25 micrometers.
Claim 5
Dependent Claim
77 words
A cable as claimed in claim 1 wherein a rAdially outer part of said dielectric wall comprises tapes formed of an extrusion-bonded laminate comprising a centre layer of a polypropylene that is substantially insoluble in said fluid and two outer layers of cellulosic paper which paper layers have i. a thickness greater than 50 micrometers but not greater than 80 micrometers ii. a density less than 0.85Mg/m3, and iii. a Gurley impermeability of at least 10,000 seconds
Claim 6
Dependent Claim
19 words
A cable as claimed in claim 6 wherein a further, radially outermost, part of the dielectric comprises paper tapes.
Claim 7
Dependent Claim
16 words
A cable as claimed in claim 1 wherein said paper has a density less than 0.75Mg/m3.
Claim 8
Dependent Claim
24 words
A cable as claimed in claim 1 wherein said paper is an uncalendered electrical grade paper of intermediate fibre length of density 0.7 Mg/m3.
Claim 9
Dependent Claim
41 words
A cable as claimed in claim 1 comprising a conductor screen defining the radially inner surface of said dielectric well and formed from a conductive extrusion-bonded laminate comprising a central layer of said polypropylene and two outer layers of cellulosic paper.
Claim 10
Dependent Claim
32 words
A cable as claimed in claim 10 in which said central conductor is a stranded conductor and wherein a lapped metal tape is interposed between said central conductor and said conductor screen.
Claim 11
Dependent Claim
41 words
A cable as claimed in claim 1 comprising a dielectric screen defining the radially outer surface of said dielectric wall and formed from a conductive extrusion-bonded laminate comprising a central layer of said polypropylene and two outer layers of cellulosic paper.
References Cited (Backward Citations)
US3194872A
Cited
US3427394A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-30 | 1977-01-29 | 1977-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-30 | 1981-01-29 | 1981-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-30 | 1985-01-29 | 1985-07-31 | $7700.00 | Window Closed / Lapsed |