US3748369A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of shielding high voltage solid dielectric power cables
Assignee: General Cable Corp
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Filing: 1971-03-08
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Granted: 1973-07-24
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Expires: 1991-03-08
Abstract
Abstract This insulation shielding for high voltage solid dielectric power cables includes a semi-conducting tape helically wrapped on the cable with overlapping convolutions. Voids that exist along the edges of the overlaps are bridged by semi-conducting coating sprayed, dipped, washed, wiped or otherwise applied substantially uniformly in thickness around the circumference of the insulation and lengthwise thereof. This bridging of the voids on the inner side thereof prevents corona in the voids and increases the voltage rating of the cable. The coating is bonded to the tape much more strongly than it is to the insulation so that the coating is pulled off the insulation when the tape is removed for terminations. The invention includes method aspects of applying the coating and the tape wrapping.
Inventors
- 👤 F Destito
- 👤 M Durakis
- 👤 D Silver
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:13
CPC Classifications
H; H01; H01B; H01B13/00; H01B13/22; H01B13/26; H01B9/00; H01B9/02; H01B9/027
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
49 words
The high voltage power cable described in claim 1 characterized by the semi-conducting coating being a layer of substantially uniform thickness adhered to the insulation but much more strongly adhered to the semi-conducting shielding tape, and the semi-conducting shielding tApe being applied to the insulation with a helical wrap.
Claim 2
Dependent Claim
73 words
The high voltage power cable described in claim 1 characterized by the tape being applied to the insulation over said coating with an overlapping helical wrap with voids where convolutions of the tape in contact with the coating extend outward to overlap the next convolution of the tape, the tape being a semi-conducting tape and the semi-conducting coating on the insulation bridging the voids of said overlaps to prevent corona in said voids.
Claim 3
Dependent Claim
70 words
The high voltage power cable described in claim 1 characterized by the semi-conducting coating being a thermoplastic material and the insulation having a cross linked polymer surface to prevent formation of any substantial bond between the semi-conducting coating and the insulation, the semi-conducting tape having on its inside surface a semi-conducting uncured elastomeric skim that forms a strong bond to the semi-conducting coating when the cable is subjected to heat.
Claim 4
Dependent Claim
48 words
The high voltage power cable described in claim 3 characterized by an extruded plastic jacket over the outside of the tape and filling in irregularities on the outside of the tape caused by overlapping of convolutions of the tape and providing a smooth outside surface for the cable.
Claim 5
Dependent Claim
111 words
The high voltage power cable described in claim 4 characterized by coating being coatingbeing a mixture of conductive carbon black dispersed in a solution of polyethylene dissolved in toluene and the coating being a mixture that dries to a smooth non-tacky surface and of a thickness of approximately 1 to 3 mils and the coating being compatible with insulation from the group consisting of butyl, ethylene propylene rubber (EPR), both the terpolymer and the copolymer, styrene-butadiene rubber (SBR), polyvinyl chloride (PVC), cross-linked polyethylene and other polyolefins, the semi-conducting tape having on its inside surface a semi-conducting uncured elastomeric skim, the total thickness of the tape being between 9 and 11 mils.
Claim 6
Dependent Claim
123 words
A high voltage solid dielectric power cable including a conductor, a coating of semi-conducting material on the conductor, insulation surrounding the semi-conducting coating, a coating a semi-conducting material on the insulation and in continuous contact with the insulation circumferentially and longitudinally, a helical wound insulation shielding tape surrounding the insulation and having overlapping convolutions with some voids under the tape at the end of the overlaps of the tape convolutions, each void being of generally triangular longitudinal cross section and being bounded at one end by an edge of the tape and at its other respective sides by the inside surface of the tape and the outside surface of the coating of semi-conducting material on the insulation whereby the voids are rendered harmless.
Claim 7
Dependent Claim
56 words
The high voltage power cable described in claim 7 characterized by the coating on the insulation being from 1 to 3 mils in thickness and having a smooth, non-tacky surface bridging the voids, and the tape being of substantially greater thickness than the coating, and the overlapping portions of the tape being bonded to each other.
Claim 8
Independent Claim
106 words
The method of shielding a high voltage solid dielectric power cable which comprises applying to the outside surface of a cross-linked insulated conductor a semi-conducting coating containing electrically conductive particles dispersed through a thermoplastic carrier dissolved in a solvent applying the semi-conducting coating as a continuous covering around the circumference of the cross-linked insulation and lengthwise thereof, drying the coating to a smooth non-tacky surface by evaporation of the solvent, and after the coating is dry helically wrapping the coated insulation with a semi-conducting tape having overlapping convolutions with voids at edges of the overlaps, the voids being bridged by the semi-conducting coating on the insulation.
Claim 9
Dependent Claim
55 words
The method described in claim 9 characterized by cross-linking the insulation prior to coating it, using a semi-conducting thermoplastic as the coating, applying the semi-conducting tape with an inside surface that is uncured elastomer with electrically cpmdictive carbon black dispersed therein, and heating the cable to bond the thermoplastic semi-conducting coating to the uncured elastomer.
Claim 10
Dependent Claim
113 words
A high voltage cable comprising a conductor, a shielding layer of semi-conducting material on the conductor, a primary insulating layer of extruded material covering such shielding layer and having minute depressions in its outer surface, a semi-conducting tape wound around said insulating layer along substantially the entire cable length and partially lapped, resulting in a void where the tape overlaps, and a coating of semi-conducting adhesive dried on the outer surface of the insulating layer throughout its length and covered by the tape, said adhesive filling said depressions, enclosing and rendering harmless said void along the lap of the overlying tape, and having stronger adhesion to the tape than to said insulating layer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |