Tubular Cover Assemblies for Electrical Cable Stress Control
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Solution Overview
Problem
High voltage polymeric insulated electrical transmission cables require effective electrical stress control at terminations, which existing solutions often fail to provide efficiently, especially in terms of inventory management and mechanical support.
Innovation Solution
A method involving a tubular cover member mounted around the cable with a cavity filled by a flowable electrical stress grading material, evacuated using a vacuum to compact the material and provide stress control, along with a supplemental filler for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stress control elements (heat shrinkable tubes with metal-oxide filled mastics or cold shrink tubes) are used, then electrical stress control is provided, but the system complexity and inventory requirements increase
Solution Approach 1:
The patent combines the stress control function and the protective cover function into a single integrated unit. The stress control elements (metal-oxide powder and elastomeric matrix) are embedded directly within the cover member structure, eliminating the need for separate stress control tubes and reducing overall system complexity while maintaining effective electrical stress control
Solution Approach 2:
The cover member serves multiple functions simultaneously: it provides mechanical protection, electrical stress control, and environmental sealing. By integrating these functions into one component rather than requiring separate elements for each function, the patent reduces inventory requirements and simplifies the termination system
2Reliability
If liquid-filled or flexible terminations are used, then stress control is achieved, but mechanical support and self-supporting capability are reduced
Solution Approach 1:
The patent uses a composite material structure combining metal-oxide powder particles embedded in an elastomeric matrix. This composite provides both the electrical stress control properties of the metal-oxide and the mechanical strength and flexibility of the elastomeric material, achieving stress control while maintaining self-supporting mechanical capability
Solution Approach 2:
The elastomeric matrix acts as a flexible structural component that provides both mechanical support and allows the stress control elements to function effectively. The flexible nature of the elastomeric material enables the cover to adapt to cable movements while maintaining structural integrity and self-supporting properties
3Reliability
If multiple separate components are used for stress control, then comprehensive protection is provided, but ease of operation and installation are reduced
Solution Approach 1:
The patent merges multiple protective functions into a single pre-assembled cover member that can be installed in one operation. The integrated design eliminates the need for separate installation steps for different protective elements, significantly improving ease of operation and installation while maintaining comprehensive protection
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 solution effectively reduces electrical stress, provides mechanical support, and offers a flexible, easy-to-apply, self-supporting termination system that can be adapted to various cable sizes, ensuring reliable protection and weather resistance.
Implementation Method 1
applying a vacuum to the cavity to evacuate air from the cavity and compact the electrical stress grading material in the cavity
Data Source
AI summary
A method for forming a cover assembly on an electrical power transmission cable includes: mounting a tubular cover member around the cable such that a portion of the cover member defines a cavity surrounding the cable; providing a flowable electrical stress grading material in the cavity; and applying a vacuum to the cavity to evacuate air from the cavity and compact the electrical stress grading material in the cavity.