EP0076579A1 - Ecran d'isolation pour câble à haute tension - Google Patents

Ecran d'isolation pour câble à haute tension Download PDF

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Publication number
EP0076579A1
EP0076579A1 EP82304808A EP82304808A EP0076579A1 EP 0076579 A1 EP0076579 A1 EP 0076579A1 EP 82304808 A EP82304808 A EP 82304808A EP 82304808 A EP82304808 A EP 82304808A EP 0076579 A1 EP0076579 A1 EP 0076579A1
Authority
EP
European Patent Office
Prior art keywords
insulation
coating
cable
tape
dielectric constant
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.)
Withdrawn
Application number
EP82304808A
Other languages
German (de)
English (en)
Inventor
George Bahder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cable Technology Laboratories Inc
Original Assignee
Cable Technology Laboratories Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Cable Technology Laboratories Inc filed Critical Cable Technology Laboratories Inc
Publication of EP0076579A1 publication Critical patent/EP0076579A1/fr
Withdrawn legal-status Critical Current

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
    • H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
    • H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
    • H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes

Definitions

  • This invention relates to extruded-type high voltage cables, and in particular to those cables including an insulation shield formed of semi-conducting tape.
  • a high voltage cable to which the present invention is applicable typically comprises a metal conductor which is surrounded by a semi-conducting conductor shield, a body of polymeric insulation, a semi-conducting insulation shield, a metallic shield and an overall covering such as polyethylene or polyvinyl chloride (PVC).
  • the insulation shield may be, for example, a body of semi-conducting compound which is extruded over the insulation. It is particularly advantageous, however, for this insulation shield to be formed of semi-conducting tape which is applied helically over the insulation. Such a tape-type insulation shield offers the advantage of being easily stripped back when it is desired to splice or terminate an end of the cable.
  • a tape-type insulation shield such as the one above described, is typically applied in a manner such that the edges of adjacent windings of the tape overlap over about 10 to 50% of the area of the tape. Gaseous voids facing the insulation are thus formed under the tape in the region of these overlapped edges.
  • An insulation material in accordance with the present invention should have an apparent dielectric constant higher than that of the insulation.
  • the high apparent dielectric constant together with the semi-conducting nature of the tape results in considerably decreased voltage stresses in the gaseous voids at the overlapped edges of the tape. Partial discharges in the gaseous voids are thereby eliminated at normal operating voltages and under typical overvoltage conditions.
  • this coating provides a strong bond to the semi-conducting tape and a modest bond to the insulation surface.
  • the semi-conducting tape is removed prior to cable termination, therefore, most of the coating is removed with it.
  • any residual coating which is left on the cable surface will not affect the performance of the cable termination because of the insulating nature of the residue.
  • an additional advantageous aspect of the present invention is that the coating fills any scratches which may be present on the surface of the insulation layer of the cable. Due to the insulating nature of the coating, high local voltage stresses within the scratches are avoided and the life expectancy of the cable is, thereby, further extended.
  • the cable includes a metallic conductor 1, which may be solid or stranded, a semi-conducting conductor shield 2, and a body of polymeric insulation 3 which may, for example, be formed of a material such as polyethylene, cross-linked polyethylene or ethylene propylene rubber.
  • the surface of the insulation 3 is coated with a high dielectric constant insulating material 4 in accordance with the present invention.
  • the coated insulation layer is covered by an insulation shield 5 which comprises semi-conducting tape which is applied helically over the insulation with the overlap between adjacent windings being typically between 10 to 50%.
  • An extruded jacket 6 of, for example, polyethylene or polyvinylchloride (PVC) is typically applied over the insulation shield.
  • Such a cable may also include a metallic shield (not shown in the diagrams) between the insulation shield 5 and the cable jacket 6.
  • a gaseous void will typically exist in the region at which adjacent edges of the insulation shield overlap (indicated by reference numeral 10). If it were not for the presence of the high dielectric constant coating 4 of the present invention, partial discharges would occur in these voids under the high voltage stress conditions typical of normal operation of the cable. These partial discharges would cause decomposition of the portion of the insulation 3 facing the void in which the partial discharge occurred. In the cable of the present invention , however, presence of the high dielectric constant coating 4, in combination with the semi-conducting nature of the insulation shield 5, acts to reduce the voltage stresses in the void, thereby preventing the occurrence of partial discharges and the consequent decomposition of the insulation.
  • Reference numeral 7 of Figure 2 indicates an area of the insulation at which its surface has been scratched. Even if great care is taken during the manufacture of the cable it is impossible to completely prevent the occurrence of such scratches.
  • the high dielectric constant coating 4 fills the scratches thereby preventing high local voltage stresses from occurring at the ends of the scratches. Partial discharges are thereby prevented from occurring within the scratches and the degradation of the insulation and premature cable failure caused by such discharges is therefore, avoided. It will be appreciated that if such scratches were left unfilled, or if they were filled with a semi-conducting material, high local voltage stresses and/or partial discharges would occur within the scratches thereby causing degradation of the insulation and consequent premature cable failure.
  • the insulation coating 4 should be an insulating material which has an apparent dielectric constant higher than that of both the insulation 3 and the insulation shield tape 5. It may be paint-type material (eg. one which is suitable for application by spraying, dipping, washing, wiping, etc.) or a material suitable for extrusion over the insulation. It has been found, however, that a paint-type coating is best suited for being removed with the conductor shield tape during termination operations, and is thus preferable.
  • a paint-type coating as above described may be obtained by dispersing a high dielectric constant filler material in solution comprising a polymer or copolymer which has a dielectric constant similar to that of the material comprising the insulation layer of the cable , and a suitable solvent such as toluene.
  • the filler material may be titanium dioxide powder or a material having a similar dielectric constant (eg. a material having a dielectric constant of approximately 3.0 or above).
  • the polymeric material may be one such as polymer butyl rubber, ethylene propylene rubber or polyethylene.
  • the concentration of the filler in the coating should be in the range of about 20 to 60% by weight.
  • the amount of solvent in the coating depends upon the desired viscosity of the coating and typically should be increased with increases in the amount of filler utilised.
  • the semi-conducting tape employed as the insulation shield should be one of uncured butyl rubber, uncured ethylene propylene rubber or other forms of uncured plastics.
  • the coating should be dried before the application of the semi-conducting tape because the solvent may adversely affect the adhesion properties of the coating to both the surface of the insulation and to the semi-conducting tape.
  • An alternative embodiment of the insulation coating 4 is one which is suitable for extrusion over the insulation.
  • a material may be obtained by dispersing a filler material such as above described in a material such as ethylene vinyl acetate copolymer, ethylene propylene rubber or any other copolymer which is suitable for mixing with the filler employed.
  • the amounts of filler material in the dispersion should be in the range of about 20 to 60% by weight. If such an extruded insulation coating is employed, cured cross-linked tape may be employed to form the insulation shield.
  • the thickness of the coating should be in the range of approximately 1 to 10 mils.
  • the desired thickness may be obtained by appropriately selecting the relative proportions of filler material and solvent to be utilised.

Landscapes

  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Cable Accessories (AREA)
  • Insulated Conductors (AREA)
  • Manufacturing Of Electric Cables (AREA)
EP82304808A 1981-10-07 1982-09-13 Ecran d'isolation pour câble à haute tension Withdrawn EP0076579A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US30940181A 1981-10-07 1981-10-07
US309401 1981-10-07

Publications (1)

Publication Number Publication Date
EP0076579A1 true EP0076579A1 (fr) 1983-04-13

Family

ID=23198081

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82304808A Withdrawn EP0076579A1 (fr) 1981-10-07 1982-09-13 Ecran d'isolation pour câble à haute tension

Country Status (4)

Country Link
EP (1) EP0076579A1 (fr)
JP (1) JPS5882414A (fr)
BR (1) BR8205888A (fr)
ES (1) ES8401670A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986003880A1 (fr) * 1984-12-22 1986-07-03 Bp Chemicals Limited Stratifie a couches pelables
EP0212832A2 (fr) * 1985-08-08 1987-03-04 PIRELLI GENERAL plc Procédé de jonction ou de terminaison de cable électrique
WO1999008288A1 (fr) * 1997-08-06 1999-02-18 Schenectady International, Inc. Revetement resistant aux decharges partielles destine aux fils laques
CN105355330A (zh) * 2015-11-07 2016-02-24 南京南瑞集团公司 一种中压交联电缆故障修复方法
CN113348524A (zh) * 2019-05-24 2021-09-03 埃赛克斯古河电磁线日本有限公司 绝缘电线、线圈和电气/电子设备
CN114410022A (zh) * 2022-03-11 2022-04-29 桂林理工大学 一种半导电橡皮及其制备方法
CN116543970A (zh) * 2023-07-05 2023-08-04 特变电工(德阳)电缆股份有限公司 一种紧凑型金属屏蔽结构中压电缆

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL80889A0 (en) * 1985-12-17 1987-03-31 Signatron Signal source distortion compensator
GB201409065D0 (en) 2014-05-21 2014-07-02 Castrol Ltd Fluid system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3287489A (en) * 1964-09-08 1966-11-22 Kerite Company Insulated high voltage cables
US3748369A (en) * 1971-03-08 1973-07-24 Gen Cable Corp Method of shielding high voltage solid dielectric power cables
US4008367A (en) * 1974-06-24 1977-02-15 Siemens Aktiengesellschaft Power cable with plastic insulation and an outer conducting layer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3287489A (en) * 1964-09-08 1966-11-22 Kerite Company Insulated high voltage cables
US3748369A (en) * 1971-03-08 1973-07-24 Gen Cable Corp Method of shielding high voltage solid dielectric power cables
US4008367A (en) * 1974-06-24 1977-02-15 Siemens Aktiengesellschaft Power cable with plastic insulation and an outer conducting layer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986003880A1 (fr) * 1984-12-22 1986-07-03 Bp Chemicals Limited Stratifie a couches pelables
EP0188118A1 (fr) * 1984-12-22 1986-07-23 BP Chemicals Limited Construction lamellée ayant des couches dénudables
US4767894A (en) * 1984-12-22 1988-08-30 Bp Chemicals Limited Laminated insulated cable having strippable layers
EP0212832A2 (fr) * 1985-08-08 1987-03-04 PIRELLI GENERAL plc Procédé de jonction ou de terminaison de cable électrique
EP0212832A3 (en) * 1985-08-08 1988-12-28 Pirelli General Plc Electric cables
WO1999008288A1 (fr) * 1997-08-06 1999-02-18 Schenectady International, Inc. Revetement resistant aux decharges partielles destine aux fils laques
US6337442B1 (en) 1997-08-06 2002-01-08 Schenectady International, Inc. Coating which is resistant to partial discharges, for enamelled wire
CN105355330A (zh) * 2015-11-07 2016-02-24 南京南瑞集团公司 一种中压交联电缆故障修复方法
CN113348524A (zh) * 2019-05-24 2021-09-03 埃赛克斯古河电磁线日本有限公司 绝缘电线、线圈和电气/电子设备
CN114410022A (zh) * 2022-03-11 2022-04-29 桂林理工大学 一种半导电橡皮及其制备方法
CN116543970A (zh) * 2023-07-05 2023-08-04 特变电工(德阳)电缆股份有限公司 一种紧凑型金属屏蔽结构中压电缆
CN116543970B (zh) * 2023-07-05 2023-09-29 特变电工(德阳)电缆股份有限公司 一种紧凑型金属屏蔽结构中压电缆

Also Published As

Publication number Publication date
BR8205888A (pt) 1983-09-06
ES516277A0 (es) 1983-12-16
JPS5882414A (ja) 1983-05-18
ES8401670A1 (es) 1983-12-16

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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AK Designated contracting states

Designated state(s): BE DE FR GB IT LU NL SE

17P Request for examination filed

Effective date: 19830414

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19840927

RIN1 Information on inventor provided before grant (corrected)

Inventor name: BAHDER, GEORGE