High Voltage Bushing Semiconductive Glaze Corona Control
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Solution Overview
Problem
High voltage bushings face challenges in reducing corona and flashover discharges, which can lead to reduced reliability and lifespan due to high electric fields and moisture condensation, especially when used in high-voltage applications like turbines.
Innovation Solution
The bushing assembly incorporates semiconductive glaze bands on the outer surface of the insulating sleeve, adjacent to the flange, with a non-semiconductive glaze on other portions, enhancing corona and flashover resistance by managing electric fields and preventing moisture condensation, and an electrically conductive adhesive connects the flange to the semiconductive glaze bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high voltage is applied to the conductor, then power transmission capability is improved, but corona discharge and flashover risk increase
Solution Approach 1:
The insulating sleeve is applied with semiconductive glaze in specific zones (at the ends and/or in the middle portion) rather than uniformly across the entire surface. This localized treatment creates regions with different electrical properties where the semiconductive glaze provides voltage grading and field control exactly where electric field concentration occurs, while other regions maintain their original insulating properties.
Solution Approach 2:
The semiconductive glaze changes the surface electrical resistance parameter of the insulating sleeve in treated zones. By controlling the thickness and composition of the semiconductive layer, the surface resistance is reduced in specific areas to create a gradual voltage gradient, preventing sudden field breakdown and corona discharge while maintaining overall insulation integrity.
2Reliability
If the insulating sleeve surface is treated to reduce electric fields, then flashover resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The insulating sleeve is created as a composite structure combining the base insulating material (such as porcelain or polymer) with a semiconductive glaze layer applied in specific zones. This composite approach integrates the voltage grading function directly into the insulating component itself, eliminating the need for separate external grading devices or complex multi-component assemblies.
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 semiconductive glaze bands significantly reduce electric fields on the outer surface, minimizing flashover and corona discharges, thereby improving the reliability and lifespan of the bushing by preventing moisture condensation and ambient pollution deposits.
Implementation Method 1
The semiconductive glaze bands significantly reduce electric fields on the outer surface, minimizing flashover and corona discharges
Implementation Method 2
improving the reliability and lifespan of the bushing by preventing moisture condensation and ambient pollution deposits
Data Source
AI summary
A high voltage bushing assembly includes an insulating sleeve which is made of high strength alumina porcelain to surround a conductor, a flange located on an outside surface of the insulating sleeve, and a band of semiconductive glaze located on the outer surface of the insulating sleeve spaced apart from an end of the insulating sleeve.