GB2179196A - Electric cables - Google Patents
Electric cables Download PDFInfo
- Publication number
- GB2179196A GB2179196A GB08519967A GB8519967A GB2179196A GB 2179196 A GB2179196 A GB 2179196A GB 08519967 A GB08519967 A GB 08519967A GB 8519967 A GB8519967 A GB 8519967A GB 2179196 A GB2179196 A GB 2179196A
- Authority
- GB
- United Kingdom
- Prior art keywords
- layer
- semi
- conducting
- extruded
- insulating layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B9/00—Power cables
- H01B9/02—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients
- H01B9/027—Power cables with screens or conductive layers, e.g. for avoiding large potential gradients composed of semi-conducting layers
Landscapes
- Insulated Conductors (AREA)
- Resistance Heating (AREA)
- Cable Accessories (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Organic Insulating Materials (AREA)
- Ignition Installations For Internal Combustion Engines (AREA)
- Processing Of Terminals (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
- Coupling Device And Connection With Printed Circuit (AREA)
- Laminated Bodies (AREA)
Abstract
An electric cable having a current carrying conductor provided with an extruded polymeric insulating layer, has a layer of a high permittivity material extruded over the whole length of the insulating layer, which layer is covered with semi-conducting tape in contact therewith. In the embodiment a semi-conducting layer is provided between the conductor and the insulating layer and a metallic earth screen is provided over the semi-conducting tape. The high permittivity material may be nitrile rubber containing anatase.
Description
1
SPECIFICATION
Electriccables 1 1 10 GB 2 179 196 A 1 This invention relates to electric cables, and more 70 particularlyto electric cables in which the current carrying conductors are provided with extruded polymeric insulating layers.
In known high voltage cables in which the cu rrent carrying conductors are provided with extruded polymeric insulation, a layer of polymeric insulation is disposed overthe conductorwith a firstsemi conducting layer between the conductor and insula tion and a second semi-conducting layeroverthe insulation, and a conducting sheath is provided over the second semi-conducting layerto provide an earth screen. It is conventional to co-extrudethe semi conducting layers with the insulating layerwhereby the semi-conducting layers are bonded tothe insulat ing layer. The purpose of the semi-conducting layer is to prevent electrical discharges occurring duetc, voids being present between the inner surface of the insulating layer and the conductor and between the outer surface of the insulating layer and the conduct ing sheath.
The semi-conducting layer overthe insulating layer hasto be removed during jointing ortermination of the cable in the region of thejoint ortermination as it normally has a resistance such that itwouldcarry unacceptable high currents if itwere allowed to form a path between the current carrying conductor and earth in thejoInt ortermination. Removal of the semi-conducting layeroverthe insulting layerthere from is a difficult operation which involvesthe riskof damage being caused to the insulation layer. 100 To avoidthis problem, it has been proposedto provide overthewhole length of the insulation layera layerof highly resistive material whose resistance is voltage dependent insead of a semi-conducting layer since such a voltage dependent resistive layer does not haveto be removed during jointing ortermination.
However, this solution suffers from the disadvantage that material with the appropriate voltage dependent resistivity is not suitable for application by conven tional extrusion equipment.
The present invention seeks an alternative solution in which the semi-conducting layeroverthe insulating layer is replaced by an alternative layerwhich can be readilyextruded overthe insulating layer butwhich does not haveto be removed during jointing or terminating.
The present invention provides an electric cable having at least one current carrying conductor pro vided with an extruded polymeric insulating layer, overthe whole length of which Is an extruded layer of material having a relative permittivity of 20 or more, said latter layer being covered with semi-conducting tape in contact therewith.
In orderthatthe invention may be well understood an embodiment thereof, which is given by way of example only, will now be described.
The embodiment comprises a high voltage electric cable with a single current carrying conductor. A layer of semi-conducting material is extruded overthe conductor. A layer of polymeric insulating material is extruded overthe layer of semi-conducting material and a layer of high permittivity material, that is a material with a relative permittivity of, say, 20 to 30, or even more, is extruded overthe layer of insulating material. All three extruded layers extend the whole length of the conductor and the insulating layer is bonded to the layers on each side of it. The three layers may be co-extruded or extruded in separate operations on the cable length.
In orderto fulfil its functions of preventing electrical discharges the high permittivity layer is covered with semi-conducting tape which is lapped around the high permittivity layer in contact with the outer surface thereof. The semi-conducting tape may include a dessicant. Whilst it is preferable that the entire surface of the high permittivity layer be contacted bythe semi-conducting tape small breaks in such contactwill not give rise to electrical discharges because of the high permittivity of the layer. A conventional metallic earth screen is provided overthe semi-conducting tape.
When making a joint ortermination the semiconducting tape overthe high permittivity layer is stripped back by simple unwinding thereof to the termination Of the earth screen, but since the hight permittivity layerwill carry negligible current if left in a position at a joint ortermination, it does not have to be strippedfrom the insulation layer. This not only simplifies jointing and terminating operations and eliminates the possibility of damage to the insulation layer's outer surface but also assists stress distribution within the joint ortermination as the high permittivity layertends to reducethe surface gradient at the earth screen termination.
Claims (3)
1. An electric cable having at least one current carrying conductor provided with an extruded polymeric insulating layer, overthe whole length of which Is an extruded layer of material having a relative permittivity of 20 or more, said latter layer being coveredwith semi-conducting tape in contacttherewith.
2. A cable as claimed in claim 1, wherein said semi-conducting tape includes a dessicant.
3. An electric cable as claimed in claim land substantially as herein described.
Printed in the United Kingdom for Her Majesty's Stationery Office, 8818935, 2187 18996. Published at the Patent Office, 25 Southampton Buildings, London WC2A lAY, from which, copies may be obtained.
Priority Applications (10)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08519967A GB2179196B (en) | 1985-08-08 | 1985-08-08 | Electric cables |
| EP86305370A EP0212832B1 (en) | 1985-08-08 | 1986-07-14 | Electric cable jointing or terminating method |
| AT86305370T ATE72497T1 (en) | 1985-08-08 | 1986-07-14 | METHOD OF CONNECTING OR TERMINATING ELECTRICAL WIRES. |
| DE8686305370T DE3683813D1 (en) | 1985-08-08 | 1986-07-14 | METHOD FOR CONNECTING OR TERMINATING ELECTRICAL CABLES. |
| DK360386A DK360386A (en) | 1985-08-08 | 1986-07-29 | ELECTRICAL CABLE |
| CA000514944A CA1266102A (en) | 1985-08-08 | 1986-07-30 | Electric cables |
| AU60755/86A AU582259B2 (en) | 1985-08-08 | 1986-07-31 | Electric cables |
| NO863120A NO863120L (en) | 1985-08-08 | 1986-08-01 | ELECTRICAL CABLES. |
| BR8603745A BR8603745A (en) | 1985-08-08 | 1986-08-06 | ELECTRIC CABLES |
| ES8601530A ES2000395A6 (en) | 1985-08-08 | 1986-08-07 | Electric cable jointing or terminating method. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08519967A GB2179196B (en) | 1985-08-08 | 1985-08-08 | Electric cables |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8519967D0 GB8519967D0 (en) | 1985-09-18 |
| GB2179196A true GB2179196A (en) | 1987-02-25 |
| GB2179196B GB2179196B (en) | 1989-01-11 |
Family
ID=10583522
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08519967A Expired GB2179196B (en) | 1985-08-08 | 1985-08-08 | Electric cables |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0212832B1 (en) |
| AT (1) | ATE72497T1 (en) |
| AU (1) | AU582259B2 (en) |
| BR (1) | BR8603745A (en) |
| CA (1) | CA1266102A (en) |
| DE (1) | DE3683813D1 (en) |
| DK (1) | DK360386A (en) |
| ES (1) | ES2000395A6 (en) |
| GB (1) | GB2179196B (en) |
| NO (1) | NO863120L (en) |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU5686773A (en) * | 1972-06-29 | 1974-12-19 | Pirelli General Cable Works | High voltage electric cables high voltage electric cables |
| US3828115A (en) * | 1973-07-27 | 1974-08-06 | Kerite Co | High voltage cable having high sic insulation layer between low sic insulation layers and terminal construction thereof |
| US3885085A (en) * | 1974-06-11 | 1975-05-20 | Gen Cable Corp | High voltage solid extruded insulated power cables |
| US4361723A (en) * | 1981-03-16 | 1982-11-30 | Harvey Hubbell Incorporated | Insulated high voltage cables |
| EP0076579A1 (en) * | 1981-10-07 | 1983-04-13 | Cable Technology Laboratories, Inc. | Insulation shield for a high-voltage cable |
| CA1255766A (en) * | 1985-02-06 | 1989-06-13 | Richard Lloyd | High frequency attenuation cable and harness |
| BR8600498A (en) * | 1985-02-06 | 1986-10-21 | Raychem Corp | HIGH FREQUENCY ATTENUATION CABLE AND BEAM |
-
1985
- 1985-08-08 GB GB08519967A patent/GB2179196B/en not_active Expired
-
1986
- 1986-07-14 DE DE8686305370T patent/DE3683813D1/en not_active Expired - Lifetime
- 1986-07-14 EP EP86305370A patent/EP0212832B1/en not_active Expired - Lifetime
- 1986-07-14 AT AT86305370T patent/ATE72497T1/en active
- 1986-07-29 DK DK360386A patent/DK360386A/en not_active Application Discontinuation
- 1986-07-30 CA CA000514944A patent/CA1266102A/en not_active Expired - Lifetime
- 1986-07-31 AU AU60755/86A patent/AU582259B2/en not_active Ceased
- 1986-08-01 NO NO863120A patent/NO863120L/en unknown
- 1986-08-06 BR BR8603745A patent/BR8603745A/en not_active IP Right Cessation
- 1986-08-07 ES ES8601530A patent/ES2000395A6/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB8519967D0 (en) | 1985-09-18 |
| AU6075586A (en) | 1987-02-12 |
| NO863120D0 (en) | 1986-08-01 |
| ES2000395A6 (en) | 1988-02-16 |
| GB2179196B (en) | 1989-01-11 |
| EP0212832B1 (en) | 1992-02-05 |
| NO863120L (en) | 1987-02-09 |
| EP0212832A2 (en) | 1987-03-04 |
| EP0212832A3 (en) | 1988-12-28 |
| ATE72497T1 (en) | 1992-02-15 |
| DK360386D0 (en) | 1986-07-29 |
| DK360386A (en) | 1987-02-09 |
| CA1266102A (en) | 1990-02-20 |
| AU582259B2 (en) | 1989-03-16 |
| DE3683813D1 (en) | 1992-03-19 |
| BR8603745A (en) | 1987-03-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19980808 |