EP0360238A2 - Energiekabel - Google Patents

Energiekabel Download PDF

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Publication number
EP0360238A2
EP0360238A2 EP89117373A EP89117373A EP0360238A2 EP 0360238 A2 EP0360238 A2 EP 0360238A2 EP 89117373 A EP89117373 A EP 89117373A EP 89117373 A EP89117373 A EP 89117373A EP 0360238 A2 EP0360238 A2 EP 0360238A2
Authority
EP
European Patent Office
Prior art keywords
semiconductor
insulation
extruded
parts
composite
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
Application number
EP89117373A
Other languages
English (en)
French (fr)
Other versions
EP0360238A3 (de
EP0360238B1 (de
Inventor
Thor Asbjorn Holte
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.)
Nexans Norway AS
Original Assignee
Alcatel STK AS
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 Alcatel STK AS filed Critical Alcatel STK AS
Priority to AT89117373T priority Critical patent/ATE85724T1/de
Publication of EP0360238A2 publication Critical patent/EP0360238A2/de
Publication of EP0360238A3 publication Critical patent/EP0360238A3/de
Application granted granted Critical
Publication of EP0360238B1 publication Critical patent/EP0360238B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/06—Insulating conductors or cables
    • H01B13/14—Insulating conductors or cables by extrusion

Definitions

  • the present invention relates to power cables and in particular to power cables having a conductor, a number of fully bonded dielectric layers including an extruded semi­conductor over the conductor, one or more layers of extruded insulation material over the inner semiconductor and an outer extruded semiconductor over the insulation, and finally an outer metal screen and possible outer protective shields, layers and/or sheaths over the outer semiconductor.
  • Crosslinking agents such as organic peroxides are usually added to the dielectric material before or during the extrusion process to provide a fully crosslinked insulation and semiconductors.
  • the semiconductors are made semiconductive by adding conductive material such as conductive carbon black to the extrudable plastic material.
  • conductive material such as conductive carbon black
  • the presence of carbon black particles within the extruder leads to higher friction and higher temperature within the extruded material. This increases the risk of pre-crosslinking and clotting.
  • the semiconductors are also very much thinner than the insulation, and the extruder passages for the semiconductors are therefore much narrower than the passages for the insulation material. The tendency of clotting is therefore greater in the semiconductors than in the insulation.
  • the clots When the clots occur in the outer semiconductor they can usually be detected by inspection and repaired. If the clots occur in the inner semiconductor which is usually extruded in tandem with the insulation or in multiple heads, detection is very difficult or impossible.
  • Clots at this interface is also critical because the voltage gradient is higher than at the interface between the insulation and the outer semiconductor.
  • the object of the present invention is to improve the dielectric properties of power cables with extruded insulation. This object is obtained by ensuring that the interfaces between the semiconductors and the insulation are smooth and free from clots and lumps which may protrude into the insulation.
  • Multiple head extruders may be used to extrude the inner and outer parts of the composite semiconductor(s).
  • the inner and outer parts of each semiconductor will however, be integrally united, in spite of the fact that crosslinking agents, in accordance with the invention, are not added to the inner parts before or during the extrusion process.
  • a cable conductor 2 is provided with an extruded composite semiconductor 3, one or more layers of extruded insulation material 4 such as crosslinked polyethylene, an outer extruded composite semiconductor 5 and an outer metal screen and possible outer protective screens, layers and/or sheaths 6. All the dielectric layers are fully bonded.
  • the semiconductor 3 is extruded in two parts, - an outer part 3a, and an inner part 3b - to constitute a composite semiconductor.
  • the outer part 3a of the composite semiconductor which part contains crosslinking agents per se, clots or lumps or other protrusions 9, 10 may occur on the surface of the layer.
  • the insulation layers are extruded directly over the crosslinked semiconductor with the risk that said protrusions may cause breakdown of the cable insulation.
  • the material used for extruding the inner part 3b of the composite semiconductor 3 is, in accordance with the invention, free from crosslinking agents. No clots will therefore occur in the extrusion channels for the inner part 3b of the inner composite semiconductor 3, and the interface 7 between this semiconductor 3 and the inner surface of the insulation layers 4 will be very smooth and free from protrusions into the insulation.
  • the thickness of the inner part 3b should be large enough to cover or at least smoothen the possible protrusions occurring in the outer part 3a.
  • the outer semiconductor 5 may also be extruded in two parts - an inner part 5b and an outer part 5a - to constitute a composite semiconductor.
  • the material used for extruding the inner part 5b of the composite semiconductor is free from crosslinking agents. No clots or protrusions will therefore occur at the outer surface 8 of the insulation layers 4 and this surface will be smooth.
  • the thickness of the inner part 5b should be large enough to cover or smoothen possible clots or protrusions 11, 12 occurring in the extruded outer part 5a.
  • the inner parts 3b and 5b of the composite semiconductor will also be crosslinked in the final cable, due to migration of crosslinking agents. In some cases it may, however, be preferred to use relatively thick inner parts 3b and/or 5b when it is allowable to leave some of the semiconductive material in its thermoplastic state.
  • Typical materials which can be used for the composite semiconductors 3 and 5 are copolymers of ethylene with addition of conductive carbon black.
  • the only difference between the material used to extrude the semiconductive inner parts 3b, 5b and the outer parts 3a, 5a is that crosslinking agents such as organic peroxides are added to the material for the latter parts.
  • crosslinking agents such as organic peroxides are added to the material for the latter parts.
  • the base materials are substantially identical, said parts will be fully bonded to each other and to the insulation.
  • Typical dimensions (thickness of the dielectrics) for a 145 kV cable are: Inner semiconductor 3: 2 mm Insulation layers 4: 21 mm Outer semiconductor 5: 1 mm The thickness of the inner parts of the composite semiconductor should be 0.1 - 0.5 mm, preferably 0.1 - 0.2 mm.
  • the structure of the composite semiconducting layer should preferably be selected to ensure satisfactory electro­static screening properties of the layer during all steady state and transient voltage conditions to which the cable is subjected during operation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Laying Of Electric Cables Or Lines Outside (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Communication Cables (AREA)
  • Insulated Conductors (AREA)
  • Manufacturing Of Electric Cables (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Processes Specially Adapted For Manufacturing Cables (AREA)
EP89117373A 1988-09-23 1989-09-20 Energiekabel Expired - Lifetime EP0360238B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT89117373T ATE85724T1 (de) 1988-09-23 1989-09-20 Energiekabel.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO884219A NO169202C (no) 1988-09-23 1988-09-23 Kraftkabel.
NO884219 1988-09-23

Publications (3)

Publication Number Publication Date
EP0360238A2 true EP0360238A2 (de) 1990-03-28
EP0360238A3 EP0360238A3 (de) 1991-06-12
EP0360238B1 EP0360238B1 (de) 1993-02-10

Family

ID=19891263

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89117373A Expired - Lifetime EP0360238B1 (de) 1988-09-23 1989-09-20 Energiekabel

Country Status (7)

Country Link
EP (1) EP0360238B1 (de)
JP (1) JPH0770265B2 (de)
AT (1) ATE85724T1 (de)
DE (1) DE68904849T2 (de)
DK (1) DK168973B1 (de)
FI (1) FI94382C (de)
NO (1) NO169202C (de)

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3935042A (en) * 1974-07-08 1976-01-27 General Electric Company Method of manufacturing corona-resistant ethylene-propylene rubber insulated power cable, and the product thereof

Also Published As

Publication number Publication date
DE68904849D1 (de) 1993-03-25
DK168973B1 (da) 1994-07-18
EP0360238A3 (de) 1991-06-12
FI94382C (fi) 1995-08-25
FI94382B (fi) 1995-05-15
JPH02197020A (ja) 1990-08-03
EP0360238B1 (de) 1993-02-10
NO884219L (no) 1990-03-26
ATE85724T1 (de) 1993-02-15
JPH0770265B2 (ja) 1995-07-31
FI894425L (fi) 1990-03-24
DK468089A (da) 1990-03-24
NO169202B (no) 1992-02-10
NO884219D0 (no) 1988-09-23
DK468089D0 (da) 1989-09-22
FI894425A0 (fi) 1989-09-19
DE68904849T2 (de) 1993-08-12
NO169202C (no) 1992-05-20

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