Composition for a layer of a power cable and such cable

Abstract

The invention relates to a method for manufacturing a cable, including, from the inside to the outside, a central electrical conductor ( 1 ), a first semiconductor screen ( 2 ), an intermediate electric insulator ( 3 ), a second semiconductor screen ( 4 ), a metal screen ( 5 ) and an outer sheath ( 6 ), the method comprising a step of extruding a composition comprising at least one polyolefin for forming at least one layer constituting the first semiconductor screen, the intermediate electric insulator or second semiconductor screen and a step of cross-linking said layer. According to the invention, the method comprises the step of injecting, into the composition, a liquid solution containing at least one peroxide and at least one so-called cross-linking coagent, during the manufacture of said layer. The invention likewise relates to a cable manufactured by means of such a method.

1 . A composition for an intermediate electrical insulator and/or a semiconducting shield of a cable for the transportation of electrical energy, the composition comprising:
 a polyolefin,   a peroxide, and   a compound referred to as co-crosslinking agent,   wherein the composition comprises a lower percentage by weight of peroxide, with respect to the polyolefin, than the percentage by weight of the cocrosslinking agent, with respect to the polyolefin.   
     
     
         2 . The composition as claimed in  claim 1 , wherein
 the polyolefin is a polyethylene, and   the composition comprises between 0.01% and 1.2% by weight of peroxide, with respect to the polyethylene, and between 0.3% and 4% by weight of the cocrosslinking agent, with respect to the polyethylene.   
     
     
         3 . The compoistion as claimed in  claim 2 , wherein
 the composition comprises between 0.01% and 1% by weight of peroxide, with respect to the polyethylene.   
     
     
         4 . The composition as claimed in  claim 1 , wherein
 the co-crosslinking agent is a type-II cocrosslinking agent.   
     
     
         5 . The composition as claimed in  claim 1 , wherein
 the peroxide is a non-aromatic peroxide.   
     
     
         6 . The composition as claimed in  claim 1 , wherein
 the peroxide is an aromatic peroxide.   
     
     
         7 . The composition as claimed in  claim 1 , further comprising:
 at least one antioxidant compound.   
     
     
         8 . The composition as claimed in  claim 1 , wherein
 the polyolefin is a polyethylene.   
     
     
         9 . The composition as claimed in  claim 11 , wherein
 the polyethylene is a linear low density polyethylene.   
     
     
         10 . The composition as claimed in  claim 1 , further comprising:
 at least one “anti-scorching” compound.   
     
     
         11 . A cable for the transportation of electrical energy, comprising, from an inside of the cable toward an outside of the cable, a central electrical conductor, a first semiconducting shield, an intermediate electrical insulator, a second semiconducting shield, a metal shield and an external sheath, wherein
 the material of the intermediate electrical insulator and/or of the first semiconducting shield and/or of the second semiconducting shield is made from a composition comprising:   a polyolefin,   a peroxide, and   a compound referred to as co-crosslinking agent, and   the composition comprises a lower percentage by weight of peroxide, with respect to the polyolefin, than the percentage by weight of the cocrosslinking agent, with respect to the polyolefin.   
     
     
         12 . The cable as claimed in  claim 11 , wherein
 the cable is configured for transporting medium-voltage electrical energy.   
     
     
         13 . The cable as claimed in  claim 11 , wherein
 the cable is configured for transportin high-voltage electrical energy.