Silicone multilayer insulation for electric cable

Abstract

An electric cable has at least one elongated electric conductor and a multilayer insulation surrounding the electric conductor. The multilayer insulation comprising a first semiconducting layer and an electrically insulating layer, the two layers being made from a silicone rubber based composition, where the first semiconducting layer and the electrically insulating layer are co-extruded layers.

1 . Electric cable comprising:
 at least one elongated electric conductor; and   a multilayer insulation surrounding said electric conductor, said multilayer insulation having a first semiconducting layer and an electrically insulating layer, said two layers being made from a silicone rubber based composition,   wherein the first semiconducting layer and the electrically insulating layer are co-extruded layers.   
     
     
         2 . Electric cable according to  claim 1 , wherein the multilayer insulation has a second semiconducting layer made from a silicone rubber based composition, to form a 3-layer insulation, so that the first semiconducting layer, the electrically insulating layer and the second semiconducting layer are co-extruded layers. 
     
     
         3 . Electric cable according to  claim 2 , wherein the first semiconducting layer is surrounded by the electrically insulating layer, and the electrically insulating layer is surrounded by the second semiconducting layer. 
     
     
         4 . Electric cable according to  claim 1 , wherein at least one of the layers of said multilayer insulation is a crosslinked layer. 
     
     
         5 . Electric cable according to  claim 1 , wherein the multilayer insulation is surrounded by a metal shield. 
     
     
         6 . Electric cable according to  claim 1 , wherein the electric cable is a power cable supporting a voltage level of at least 5 kV. 
     
     
         7 . Process for manufacturing the electric cable as claimed in  claim 1 , wherein said method includes the step of co-extruding the layers of said multilayer insulation. 
     
     
         8 . Process according to  claim 7 , wherein the layers of the multilayer insulation are extruded simultaneously. 
     
     
         9 . Process according to  claim 7 , wherein the co-extrusion is done with the same extrusion head. 
     
     
         10 . Electric cable according to  claim 4 , wherein the layers of said multilayer insulation are crosslinked layers.