Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/02—Cable terminations
  • H02G15/06—Cable terminating boxes, frames or other structures
  • H02G15/064—Cable terminating boxes, frames or other structures with devices for relieving electrical stress
  • H02G15/068—Cable terminating boxes, frames or other structures with devices for relieving electrical stress connected to the cable shield only
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/02—Cable terminations
  • H02G15/06—Cable terminating boxes, frames or other structures

Definitions

• the present invention relates to a protective sleeve of a cable end such as a high or very high voltage electricity transmission cable and a cable end coated with a protective sleeve
• a cable end includes a conductor, an insulating jacket disposed around the conductor and having one end recessed from the end of the conductor, and a conductive cable screen disposed around the insulating jacket.
• the protective sleeve is disposed astride the cable end and the conductive end piece in order to protect the interface between the conductive end piece and the end of the insulating jacket against the deposition or infiltration pollution or water from weathering generally, the conductive tip is not Perfect for a romantic ⁇ ment supported on the entire circumference of the end of the insulating envelope so that the interstices remain at the interface between the conductive end piece and the insulating envelope. II results in a risk of electrical stresses at this interface which can lead to deterioration of the insulating envelope.
• An object of the invention is to propose a solution to limit the electrical stresses at the interface between the conductive element and the insulating envelope while providing a cable end of short length.
• a protective sleeve comprising a tubular body of insulating material comprising a conductive layer adjacent to one end of the tubular body and opening onto an internal face of the tubular body, in which an end portion of the tubular body is in a retracted state and tightly encloses a portion of a conductive tip while an adjacent portion of the tubular body is in an expanded state, and the conductive layer extends astride the end portion in a retracted state and on the adjacent portion in an expanded state.
• the conductive layer is arranged to overlap the conductive end piece and the insulating envelope.
• the conductive layer thus forms a Faraday cage limiting the formation of electrical stresses at the interface.
• the conductive end piece once in abutment and / or fixed on the cable end constitutes a fixed point of positioning of the tubular body. The conductive endpiece thus ensures that the tubular body is held in position during the retraction.
• the invention also relates to a cable end comprising a conductor having one end connected to a conductive end piece, an insulating envelope surrounding the conductor and having one end set back from the end of the conductor, a conductive screen surrounding the insulating envelope and having one end set back from the end of the insulating jacket, and an insulating sheath surrounding the conductive screen, the cable end being covered by a tubular body with a protective sleeve comprising a conductive layer opening onto an internal face of the tubular body and extending astride the conductive end piece and the end of the insulating jacket.
• FIG. 1 is a longitudinal sectional view of a protective sleeve according to the invention positioned on one end of the cable
• FIG. 2 is a view similar to Figure 1 of the protective sleeve retracted on the end of the cable .
• one end of the cable comprises a cylindrical conductor 1 conventionally formed from a series of stranded conductive wires, an insulating jacket 2 disposed around the conductor and having one end 3 set back from the end of the conductor, a conductive cable screen 4, disposed around the insulating jacket 2 and having one end set back from the end 3 of the insulating jacket, a metal shield 5 arranged around the cable screen and having one end set back from the end of the cable screen, an insulating sheath 6 surrounding the shield 5, and a grounding braid not shown in contact with the end of the shield.
• the insulating sheath, the shielding, the cable screen and the insulating envelope have a generally cylindrical structure and extend in successive layers around the conductor.
• the protective sleeve bearing the general reference 7, comprises a tubular body 8 made of insulating and elastic material so that it can be expanded radially, and a series of skirts 9 projecting outwardly around the tubular body 8.
• the tubular body a, when it is in an idle state, an internal diameter less than the minimum diameter of the cable end that it is intended to cover.
• the tubular body 8 comprises an end portion 10 in a retracted state surrounding a tubular part 12 of a tip 11 made of a conductive material.
• the tubular part 12 has an external diameter greater than the internal diameter of the tubular body 8 in a state of rest so that when the end portion 10 of the tubular body is in a retracted state it tightly encloses the conductive end piece 11.
• the conductive endpiece 11 carries two clamping screws 14 with controlled breaking force extending radially through the part 12 and the end portion 10 of the tubular body 8.
• a part 15 of the tubular body 8 adjacent to the portion end 10 is maintained in an expanded state by a rigid expanding holding tube 16 of plastic.
• the expansion holding tube 16 has an internal diameter greater than the maximum diameter of the cable end on which it is intended to be threaded.
• a conductive layer 17 extends annularly astride the end portion 10 and the part 15 of the tubular body 8.
• the conductive layer 17 opens onto the internal face 18 of the tubular body 8.
• the conductive layer 17 is for example made of a polymer made electrically conductive.
• the tubular body 8 also includes an elastic outer flange 19 adjacent to the clamping screws 14.
• the operator threads the protective sleeve 7 over the cable end until the tubular part 12 of the conductive end piece 11 abuts on the end 3 of the insulating envelope 2.
• the operator screws the clamping screws 14 for fixing the conductive end piece 11 to the conductor 1.
• the screws are designed to break when the screwing force is greater than a force corresponding to sufficient tightening of the conductor 1, so that the screw ruptured is flush with the outer surface of the conductive tip. The positioning of the protective sleeve thus produced is precise.
• the operator can therefore proceed to withdraw the expansion holding tube 16 by exerting a traction thereon in a direction opposite to the conductive end piece 11, to which the tubular body 8 is hooked by the end portion 10.
• the part 15 of the tubular body 8 then retracts onto the cable end as shown in FIG. 2.
• the conductive layer 17 is in this way in close contact with both the conductive end piece 11 and the insulating envelope 2 and thus forms a Faraday cage around the interface between the conductive endpiece il and the insulating envelope 2.
• the operator covers the broken ends of the clamping screws 14 with a sealing material. 21 and flap the collar 19 on this material.
• the invention has been described in relation to a particular preferred embodiment in which the protective sleeve encloses the end piece conductor prior to its installation on the sleeve, the invention can be implemented in the form of a fully expanded protective sleeve which is positioned and retracted after fixing the conductive end piece on the cable.
• the protective sleeve has been shown in the form of a single layer directly applied to the cable, it is possible to provide a protective sleeve comprising an internal layer of high permittivity which reduces electrical stresses, which makes it possible to reduce the length of the end without reducing its performance.

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• Cable Accessories (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9509755

Family Applications (1)

Country Status (3)

Family Cites Families (3)

• 1997
  • 1997-07-29 FR FR9709634A patent/FR2766981B1/fr not_active Expired - Fee Related
• 1998
  • 1998-07-27 EP EP98941459A patent/EP1000452A1/de not_active Withdrawn
  • 1998-07-27 WO PCT/FR1998/001655 patent/WO1999007052A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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