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AssigneeNKT HV Cables AB
InventorsPatrick MEIER, Spiros TZAVALAS, Thomas CHRISTEN, Alexey SOKOLOV, Jan VAN-LOON, Xavier KORNMANN
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A high-voltage DC cable joint including a multi-wall layered construction having individual concentrically arranged layers. The joint includes, from inside to outside, an inner conductive rubber layer, a field grading rubber layer made from a predetermined tailored formulation, an insulating rubber layer and an outer conductive rubber layer. The field grading rubber layer separates and interconnects the conductive rubber layers, and wherein the rubber layers are cross-linked by a by-product-free manufacturing method. The cable joint is preferably made from platinum cured rubbers by moulding process steps. In a preferred embodiment the cable joint is made by injection moulding.
A method of manufacturing a high-voltage DC cable joint comprising a multi-wall layered construction having individual concentrically arranged layers, and that the method comprises moulding the joint by the following moulding process steps:
A high-voltage DC cable joint comprising a multi-wall layered construction having individual concentrically arranged layers, characterized in that the joint comprises, from inside to outside, an inner conductive rubber layer, a field grading rubber layer made from a predetermined tailored material formulation, an insulating rubber layer, and an outer conductive rubber layer, wherein the field grading rubber layer is configured to separate and to interconnect the conductive rubber layers, and wherein the rubber layers are made from cross-linked rubbers by by-product-free moulding process steps, and wherein said field grading rubber layer, made from said tailored material formulation, is characterized in that, at low electric field strengths, below a predetermined electric field strength between 1 and 20 kV/mm, it has a conductivity higher than that of the insulating rubber layer at least by a factor of 10, and preferably by a factor of 100, but being sufficiently small to ensure negligible leakage current between the conductive rubber layers, and wherein said tailored material formulation is further characterized in that it has a nonlinear field grading property at voltages having an electrical field strength above said predetermined electrical field strength threshold, and wherein said tailored material formulation is tailored according to an electric breakdown field of adjacent materials and/or interfaces or triple points.
Dependencies are inferred from the claim text.