Composite Bushing Structure for Creepage and Contamination Control
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Solution Overview
Problem
Existing bushings for electrical apparatuses face challenges in providing reliable and cost-effective electrical insulation, particularly in liquid-insulated environments, with issues related to contamination, electrical breakdown, and inefficient manufacturing processes.
Innovation Solution
A bushing design utilizing a thermoplastic main part with a silicone elastomer cover, featuring a weather shed structure and chemical bonding, which enhances creepage length and reduces contamination risk, while allowing for a quick and cost-effective manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional insulator design is used, then manufacturing may be simpler, but electrical insulation reliability is reduced due to contamination and leakage currents
Solution Approach 1:
The patent introduces a weather shed structure that extends the creepage path in a third dimension (vertically), forcing leakage currents to travel a longer, more complex path around the insulator surface rather than directly across contamination layers. This dimensional extension effectively reduces the impact of contamination by increasing the electrical path length.
Solution Approach 2:
The insulator body is constructed from composite materials (such as polymer resin matrices reinforced with glass fibers or aramid papers) that combine the hydrophobic properties of polymers with the mechanical strength and electrical insulation properties of reinforcing materials. This composite structure resists contamination accumulation and maintains insulation reliability in polluted environments.
2Reliability
If ceramics are used for the insulator body, then electrical insulation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the material parameter from traditional ceramics to modern polymer composites (such as polypropylene, epoxy resin, or polyester reinforced with glass fibers). These materials offer comparable or superior electrical insulation properties while enabling simpler manufacturing processes like injection molding or compression molding, reducing both complexity and cost.
Solution Approach 2:
The patent replaces the traditional mechanical assembly of multiple ceramic parts with integrally molded composite insulator bodies. The composite materials allow for complex geometries to be formed in single manufacturing steps, eliminating the need for assembly operations and reducing manufacturing complexity while maintaining insulation performance.
3Object-affected harmful factors
If the insulator body is fully covered with elastomeric material, then hydrophobicity is improved, but material cost and manufacturing time increase
Solution Approach 1:
The patent applies elastomeric material selectively to specific regions of the insulator body where hydrophobicity is most critical, such as the outer surface and weather shed areas exposed to environmental contamination. The insulator core or internally cooled regions may use different materials optimized for their specific functions, reducing overall material cost and manufacturing complexity while maintaining necessary hydrophobic properties.
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 design provides improved electrical insulation with reduced leakage currents and surface discharges, enhanced hydrophobicity, and efficient manufacturing, resulting in a reliable and cost-effective bushing solution.
Implementation Method 1
The elastomeric material provides a hydrophobic surface. The outer surface of the outer cover does not easily collect contamination and is efficiently cleaned by rainwater during operation
Implementation Method 2
The outer cover is fixed to the main part. The outer cover adheres firmly to the main part. The chemical bond connects the cover and the main part together
Data Source
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AI summary
A bushing (100) for a liquid-insulated electrical apparatus (200) is disclosed. The bushing (100) comprises an electrical conductor (101) and an insulator body (110) through which the electrical conductor (101) extends, wherein the insulator body (110) comprises a main part (112) and an outer cover (150), the outer cover (150) covering the main part (112) at least in a middle part area (180), wherein the main part (112) and the outer cover (150) are fixed to each other, the main part is made of thermoplastic (115) and the outer cover (150) is made of elastomeric material (151) and wherein the insulator body (110) comprises a weather shed (116), the weather shed (116) being formed by a projecting part (181) of the main part (112) which is covered by the cover (150).