Load-Break Switch Shielding for Restrike Arc Prevention
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Solution Overview
Problem
Existing load-break switches for medium-voltage electrical systems using environment-friendly insulation gases face issues with restrike arcing phenomena during opening maneuvers, which can damage internal components due to lower dielectric withstand and heat capacity compared to SF6, and solutions like increasing dielectric distances or adding shielding members negatively impact other electrical performances.
Innovation Solution
A switching apparatus with a stationary shielding member comprising a conductive body that surrounds the movable contact member during the dielectric recovery phase, homogenizing the electric field and preventing restrike arcing without affecting current breaking capability, using insulation gases like dry air or environmentally friendly gas mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If environment-friendly insulation gas (dry air or gas mixtures) is used instead of SF6, then environmental compatibility is improved, but dielectric withstand and arc-quenching capability deteriorate
Solution Approach 1:
A conductive shielding member is introduced as an intermediary element between the movable contact member and the outer enclosure. This shielding member creates a controlled electric field environment that prevents restrike arcing, thereby compensating for the lower dielectric withstand capability of environment-friendly insulation gases while maintaining their environmental benefits
2Reliability
If dielectric distance between live and grounded components is increased, then restrike arcing is prevented, but apparatus size increases
Solution Approach 1:
Instead of increasing the dielectric distance in the linear dimension between contact and enclosure, the solution introduces a shielding member that operates in a different dimensional approach - creating localized electric field control zones around critical components. This allows restrike prevention without proportionally increasing the overall apparatus volume
3Reliability
If shielding members are mounted on movable contact members, then restrike arcing is reduced, but current breaking capability deteriorates
Solution Approach 1:
The conductive shielding member is strategically positioned and dimensioned to provide localized electric field control only in the critical region where restrike arcing occurs (between the movable contact member and surrounding grounded components). This localized approach prevents restrike arcing while leaving the main current breaking path and contact member geometry optimized for their primary function
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 or prevents restrike arcing, maintains high electrical performance, and ensures a compact, simple, and cost-effective structure for industrial manufacturing.
Implementation Method 1
A switching apparatus with a stationary shielding member comprising a conductive body that surrounds the movable contact member during the dielectric recovery phase, homogenizing the electric field and preventing restrike arcing
Implementation Method 2
using insulation gases like dry air or environmentally friendly gas mixtures
Data Source
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AI summary
A switching apparatus comprising: - one or more electric poles; - an outer enclosure defining an internal volume; - for each electric pole, a fixed contact member arranged in a fixed position relative to said enclosure and including a fixed contact; - for each electric pole, a movable contact member including a movable contact and reversibly movable between a closed position, at which said movable contact is coupled to said fixed contact, and an open position, at which said at movable contact is decoupled from said fixed contact. The switching apparatus comprises, for each electric pole, a shielding member including a conductive body having first surfaces defining a coupling cavity for said movable contact member and second surfaces having a rounded profile and facing one or more surrounding components of said electric pole. Said shielding member is arranged in a fixed position relative to said movable contact member and said enclosure in such a way that said movable contact member is accommodated in said coupling cavity and is surrounded at least partially by said conductive body, when said movable contact member reaches said open position.