Electric cable for medium voltage

摘要

This invention refers to a medium voltage electric cable (up to about 45 kV) comprising one or more cores, each of said cores being constituted by a conductor covered with an inner semiconductive screen, an insulation layer of extruded polymeric material (preferably, cross-linked polyethylene or ethylenepropylene rubber) and an outer semiconductive screen. The outer semiconductive screen, which is extruded on the insulation and vulcanized at the same time as the insulation in a continuous vulcanizing line, is constituted by a mixture based on a blend of nitrile rubber and ethylene-propylene rubber and containing carbon black, cross-linking agents and various additives. The blend of nitrile rubber and ethylene-propylene rubber comprises 50-70 parts by weight of nitrile rubber and 50-30 parts by weight of ethylene-propylene rubber. The so constituted outer semiconductive screen has good adhesion to the insulation and can be easily removed from said insulation.