EXTRUDING POLYMER MATERIALS FOR HIGH-VOLTAGE CABLES WITH CROSS-BOUND INSULATION

摘要

Extrusion-coating of power cables comprises cooling and cross-linking the polymer. The conductor is surrounded by an innermost semi-conductive layer, over which an insulating layer is applied which, in turn, is enveloped in an outermost semi-conductive ply. The polymer material is cooled before the cross-linking step. The polymer is pref. a polyolefin, polyethylene, or an EP elastomer. The conductor is cooled before the extrusion step. Alternatively, it may be cooled after application of the innermost semi-conductive layer but before extrusion of the other plies. In a further variant, cooling is carried out after all the polymer layers have been applied, or else both before and after extrusion of the inner most semi-conductive ply. Deformation and mis-alignment of the polymer layers is minimised i.e. the coatings are accurately centred w.r.t. the conductor.