Integrated Stress Control Module for XLPE Cable Termination
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Solution Overview
Problem
Conventional stress control modules for high voltage and ultra-high voltage cross-linked polyethylene insulated cables suffer from electric field distortion due to micro air gaps, impurities, and insulation grease at the interface between the stress cone and the cable, leading to potential insulation breakdown.
Innovation Solution
A manufacturing process for a termination injection molding stress control module that involves stripping and smoothing the cable insulation, followed by heating and extruding molten cross-linked polyethylene insulation and semiconducting material to create an integrated, melted structure that eliminates the active interface and ensures stable electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pre-manufactured stress control modules are assembled and fitted onto the cable body at site, then the manufacturing process is simple and can be done on-site, but micro air gaps, impurities, and insulation grease exist at the active interface between the stress cone and cable body, causing creeping discharge and space charge accumulation that leads to insulation breakdown
Solution Approach 1:
The patent merges the stress control module with the cable insulation body through injection molding, creating an integrated structure where the stress control layer becomes part of the cable insulation itself. This eliminates the active interface between separate components, removing the source of micro air gaps and impurities that cause creeping discharge and space charge accumulation.
Solution Approach 2:
The patent replaces the mechanical connection method (assembling and fitting pre-manufactured modules) with an injection molding process that creates a chemical and physical integration between the stress control layer and cable insulation. This substitution eliminates the interface problems associated with mechanical connections while maintaining on-site manufacturing capability.
2Manufacturing precision
If the cable insulation surface is heated to above 100 degrees to soften and fuse with the semiconductive shrinkable tube, then the interface between stress cone and cable is smoothed, but the cable insulator material begins to melt and deform if temperature exceeds its melting point
Solution Approach 1:
The patent changes the temperature parameter control during the injection molding process, maintaining it below the melting point of the cable insulation material while still achieving sufficient softening and fusion. This parameter optimization allows interface smoothing without causing material deformation or melting.
3Device complexity
If conventional stress control modules are used with active interfaces, then the manufacturing process is simple, but creeping discharge and space charge accumulation occur at the interface, leading to local electric field distortion and insulation breakdown
Solution Approach 1:
The patent combines the stress control layer with the cable insulation body through injection molding, creating an integrated structure that eliminates the active interface. This merging removes the source of creeping discharge and space charge accumulation while maintaining structural simplicity.
Solution Approach 2:
The patent converts the potential harm of interface defects into a benefit by using the injection molding process to create a seamless integration. The same interface that would normally generate harmful effects becomes a unified structure that eliminates these problems, turning the potential weakness into a strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process results in a stable electrical property for electric field stress distribution, preventing insulation breakdown and enabling on-site manufacture for both AC and DC high-voltage/ultra-high-voltage cables, including submarine cables, by integrating the stress control module with the cable body.
Implementation Method 1
extruding the molten cross-linked polyethylene insulation 4 having the same material as the cable insulation 3 into a cavity of the molding machine, and raising the temperature and performing crosslinking through heating to allow the cable insulation 3 and the cross-linked polyethylene insulation 4 to melt
Implementation Method 2
performing crosslinking through heating to allow the cable insulation 3 and the cross-linked polyethylene insulation 4 to melt, graft and combine into an integrated insulation
Implementation Method 3
when the molding machine is started up and preheated to a temperature at which a cross-linked semiconducting material melts, starting the extruder to extrude the molten semiconducting material
Implementation Method 4
raising the temperature and performing crosslinking through heating to allow the outer semiconducting layer 2 of cable 1, the cable insulation 3, the cross-linked polyethylene insulation 4 and the filling semiconducting layer 5 to melt, graft and combine with each other
Data Source
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AI summary
The present invention discloses a manufacturing process for a termination injection molding stress control module for cross-linked polyethylene insulated cable body, which comprises the steps of melting and cross-linking a cable factory insulation layer and a filling insulation; melting and cross-linking the cable factory semiconducting layer and a filling semiconducting layer; and melting and cross-linking the filling insulation and the filling semiconducting layer. The manufacturing process is convenient to operate, and the manufactured stress control module is integrated with the cable body; the electrical property of electric field stress distribution is stable, the problem that an active interface is generated between the cable and the stress control module as they are made of different materials is solved, and the problem of breakdown of cable insulation as a result of local electric field distortion of the insulating layer caused by space charge accumulation at an insulation border is avoided. The manufacturing process of the present invention breaks through the technical bottleneck in the industry worldwide that an ultra-high voltage DC cable is free of termination connection, and meets the requirements for submarine cable as well as AC and DC high-voltage/ultra-high-voltage cable termination on-site manufacture and breakdown rescue.