Power Cable Joint Insulation Taper for Higher Dielectric Strength
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Solution Overview
Problem
Existing power cables suffer from material transitions that are weak against the electric field, leading to increased dielectric strength and reduced dielectric strength at the interface between the joint insulation system, which are not perpendicular to the longitudinal axis of the cable joint, which are not perpendicular to the longitudinal axis of the cable joint, resulting in increased dielectric strength.
Innovation Solution
The method involves mechanically processing the insulation system of each cable section to create a tapering insulation layer section that tapers towards the conductor joint, with inclinations relative to the longitudinal axis, forming a joint insulation system that aligns with the electric field for optimal dielectric strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulation layer is processed with a frustoconical portion (single inclination), then the electric field is directed more perpendicular to the interface, but the dielectric strength is still insufficient at certain positions along the interface
Solution Approach 1:
The insulation layer is divided into multiple portions (first portion with first inclination, second portion with second inclination, and optionally third portion with third inclination). Each portion has a different inclination angle, creating multiple interfaces that collectively guide the electric field more effectively perpendicular to all interfaces, thereby enhancing dielectric strength throughout the entire joint structure.
Solution Approach 2:
Different portions of the insulation layer are given different local geometric properties (different inclination angles). The first portion has a first inclination suitable for its location, the second portion has a second inclination optimized for its position, and the third portion has a third inclination for its specific location. This local optimization ensures that each interface is oriented to maximize dielectric strength at its specific position along the longitudinal axis.
2Reliability
If the interface between insulation layers is inclined at a single angle, then some regions benefit from improved dielectric strength, but other regions still experience weak points where breakdown can initiate
Solution Approach 1:
The interface is segmented into multiple sections with different inclination angles. The first interface portion has a first inclination, the second interface portion has a second inclination, and the third interface portion has a third inclination. This segmentation allows each section to be optimized for its specific electrical field conditions, ensuring comprehensive dielectric strength improvement across the entire joint.
Solution Approach 2:
The transitions between portions with different inclinations are made smooth and curved rather than abrupt angular changes. The smooth transitions eliminate sharp corners and stress concentration points that could serve as breakdown initiation sites, while gradually changing the interface orientation to optimize dielectric strength across the entire structure.
Data Source
AI summary
A method of making a joint of a power cable, including: a) providing two cable sections to be jointed, each cable section including a conductor having a conductor end, and an insulation system including an inner semiconducting layer arranged around the conductor, an insulation layer arranged radially outside the inner semiconducting layer, and an outer semiconducting layer arranged radially outside the insulation layer, b) mechanically processing the insulation system of each cable section by gradually increasing a radius of the insulation layer in an axial direction away from the conductor end of the cable section, to obtain a tapering insulation layer section that tapers towards the conductor end, wherein the processing is performed such that an outer surface of a radially innermost portion of the tapering insulation layer section, interfacing the inner semiconducting layer, obtains a first inclination relative to a longitudinal axis of the cable section, and that an outer surface of an intermediate portion of the tapering insulation layer section obtains a second inclination which is larger than the first inclination, wherein the outer surface of the radially innermost portion transitions smoothly to the outer surface of the intermediate portion, and c) making a joint insulation system, after the conductors of the two cable sections have been electrically connected to each other by means of a conductor joint, the joint insulation system connecting to the inner semiconducting layer of each cable section, to the tapering insulation layer section of each cable section, and to the outer semiconducting layer of each cable section.