Electricity transmission cable with mass-impregnated paper insulation

Abstract

An electricity transmission cable with mass-impregnated paper insulation has around at least one conductor (1), an impregnated paper layer (2) and a metal layer (3) adjacent to the impregnated paper layer, this metal layer (3) consisting of copper or aluminum. The cable has, directly around said metal layer (3), an insulating material layer (4) and, directly around the insulating material layer (4), a transverse reinforcement layer (5) made of steel or made of glass fiber tape.

Claims

1. Electricity transmission cable with mass-impregnated paper insulation comprising around at least one conductor, an impregnated paper layer and a metal layer adjacent to said impregnated paper layer, this metal layer consisting of copper or aluminum, wherein said electricity transmission cable has, directly around said metal layer, an insulating material layer and, directly around said insulating material layer, a transverse reinforcement layer made of steel or made of glass fibre tape.

2. Cable according to claim 1, said insulating material layer is laminated to said metal layer.

3. Cable according to claim 1, said metal layer has a thickness between 0.6 and 1.5 mm.

4. Cable according to claim 1, said metal layer is made of a strip wound in the form of a cylinder around said conductor and welded longitudinally.

5. Cable according to the preceding claim 1, wherein said strip is welded along a generatrix of said cylinder.

6. Cable according to claim 1, wherein said insulating material layer is made of polyethylene laminated by means of a polyolefin layer to said metal layer.

7. Cable according to claim 1, wherein said transverse reinforcement layer has a thickness between 0.1 and 1 mm.

8. Cable according to claim 1, intended for DC high voltages.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below in greater detail with the aid of a FIGURE that represents only one preferred embodiment of the invention.

(2) This FIGURE is a cross-sectional view of a cable in accordance with the invention, particularly intended for submarine use.

DETAILED DESCRIPTION

(3) An electricity transmission cable with mass-impregnated paper insulation, particularly intended for submarine use, comprises around at least one conductor 1, here consisting of a central cylindrical conductor and conductors of trapezoidal cross section, an impregnated paper insulation system 2 consisting of internal semi-conductive papers, insulating papers and external semi-conductive papers, and a metal layer 3.

(4) Around this metal layer 3, it also comprises an insulating material layer 4, preferably made of high-density polyethylene and having a thickness of 3 to 6 mm, laminated to the metal layer 3, a transverse reinforcement layer 5, having a yield strength of between 2010.sup.6 N and 10010.sup.6 N per meter of cable length, and an external sheath 7.

(5) This transverse reinforcement layer 5, having a thickness between 0.1 and 1 mm, has a tensile modulus greater than that of the metal layer 3 and an elastic domain such that it is capable of absorbing the variations in volume of the insulating mass in the operating range of the cable at temperature, and also handling stresses, for example coiling stresses.

(6) This transverse reinforcement layer 5 is preferably made of steel and is taped over the insulating material layer 4. It preferably has a thickness substantially equal to 0.2 mm.

(7) Advantageously, a 400 MPa to 700 MPa steel is selected.

(8) The reinforcement layer may also be made of R-glass or S-glass fibre tape and have a thickness substantially equal to 1 mm.

(9) The lamination of the insulating material layer 4 is carried out by a thin layer of functionalized polymer, preferably polyolefin, comprising pendant polar groups, which is co-extruded with the insulating material layer 4.

(10) In the case of a submarine application, a pull-resistant armour consisting of longitudinal metal wires 6, preferably made of steel, is also arranged.

(11) This metal layer 3 surrounding the impregnated paper layer consists of copper or aluminium and has a thickness of between 0.6 and 1.5 mm.

(12) This metal layer consists of a strip wound in the form of a cylinder around the conductor 1 and welded longitudinally along a generatrix of the cylinder, by a weld seam 8 produced by laser or TIG (tungsten inert gas) welding.

(13) Such a cable is intended for DC high voltages.