Resistive Coated High Voltage Bushing Mitigates Partial Discharges
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Solution Overview
Problem
Conventional high voltage bushings are prone to partial discharges due to dust or dirt particles interacting with metallic electrodes, which can lead to electrical failures.
Innovation Solution
A gas-filled high voltage bushing with a metal part coated by a resistive layer having a resistivity of 10^8-10^14 Ωm, allowing for slow and controlled discharge of particles, thereby reducing or eliminating partial discharges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic voltage grading shield is used in a gas filled bushing, then electrical field grading is achieved, but partial discharge occurs when dust particles hit the metallic surface
Solution Approach 1:
The patent changes the surface parameter of the metallic voltage grading shield by coating it with a resistive layer having specific resistivity (10^8 to 10^14 Ωm). This parameter change transforms the surface from highly conductive to resistive, enabling controlled charge dissipation that prevents partial discharge while maintaining field grading functionality.
Solution Approach 2:
The patent creates a composite structure by combining the metallic voltage grading shield with a resistive coating layer. This composite material approach allows the shield to maintain its electrical field grading capability while the resistive coating provides controlled charge dissipation, eliminating the harmful partial discharge effect.
2Stress or pressure
If a highly conductive metallic surface is used for voltage grading, then electrical field control is improved, but charge accumulation on dust particles leads to partial discharge
Solution Approach 1:
The patent modifies the surface resistivity parameter from highly conductive (metallic) to resistive (10^8 to 10^14 Ωm) by applying a resistive coating. This parameter change enables the surface to control charge accumulation rates, allowing gradual dissipation that prevents partial discharge while maintaining adequate field grading.
Solution Approach 2:
The resistive coating acts as an intermediary layer between the metallic shield and the dust particles. It mediates the charge transfer process by providing controlled conductivity, allowing charge to dissipate gradually rather than accumulating rapidly, thus preventing partial discharge while maintaining field control.
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 resistive layer effectively mitigates partial discharges, enhancing the reliability and longevity of high voltage bushings by allowing controlled particle discharge, thus reducing the risk of electrical failures.
Implementation Method 1
a layer having a resistivity in the range of 10^8-10^14 Ωm... slow and controlled discharge of particles hitting the surface
Data Source
AI summary
A high voltage bushing including a metal part provided with a resistive layer.