High voltage direct current cable having an impregnated stratified insulation

Abstract

A high voltage direct current cable includes at least one electrical conductor, at least one semiconducting layer, at least one stratified insulation made from windings of at least one paper-polypropylene laminate, the stratified insulation being impregnated with at least one electrically insulating fluid having a kinematic viscosity of at least 1,000 cSt at 60EC, wherein the laminate includes at least one paper layer having an air impermeability of at least 100,000 Gurley sec−1. Such a high air impermeability of the paper layer(s) remarkably reduces the swelling of the polypropylene layer(s) during impregnation with a high viscosity insulating fluid, thus preventing delamination, up to the end of the impregnation process for the whole stratified insulation.

Dependencies are inferred from the claim text.