Medium-Voltage Switchgear Contact Design Using Dry Air and Vacuum Interruption
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Solution Overview
Problem
Existing load-break switches for medium voltage electric systems face challenges in achieving high-level dielectric insulation and arc-quenching capabilities while minimizing environmental impact, often resulting in complex structures with poor reliability and high manufacturing costs.
Innovation Solution
A switching apparatus with electric poles featuring a movable contact system and a vacuum interrupter mechanism, utilizing a motion transmission mechanism with levers and elastic means to manage the operation of fixed and movable contacts, ensuring efficient dielectric insulation and arc-quenching in a compact design filled with environmentally friendly gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SF6 gas is used for dielectric insulation and arc-quenching, then excellent insulation performance and arc-quenching capabilities are achieved, but environmental harm increases due to SF6 being a powerful greenhouse gas
Solution Approach 1:
The patent changes the physical state parameters of the insulating medium by using pressurized dry air instead of SF6 gas. The dry air is maintained at a pressure of 1.5 to 3 bar, which enhances its dielectric strength and arc-quenching capabilities to approach SF6 performance levels while eliminating environmental harm. This parameter change (pressure elevation) allows ordinary air to achieve previously unattainable insulation performance.
Solution Approach 2:
The patent creates an inert-like environment using pressurized dry air that is filtered and maintained free from moisture and contaminants. This controlled inert atmosphere provides stable dielectric properties and effective arc quenching, replacing the harmful SF6 gas with an environmentally friendly alternative that maintains operational reliability.
2Reliability
If multiple contact arrangements (air atmosphere for current carrying, vacuum for arc-quenching) are used, then high-level arc-quenching capabilities are achieved, but device complexity increases due to complicated coordination requirements
Solution Approach 1:
The patent merges the functions of current carrying contacts and arc-quenching contacts into a single integrated contact arrangement. All contacts operate within the same pressurized dry air atmosphere, eliminating the need for separate vacuum chambers and complex coordination mechanisms. The unified design maintains high arc-quenching performance while significantly reducing structural complexity and improving reliability through fewer moving parts and interfaces.
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 apparatus provides high-performance dielectric insulation and arc-quenching capabilities, enhances structural compactness and reliability, and allows for cost-effective industrial manufacturing, while using environmentally friendly gases.
Implementation Method 1
A contact arrangement has electric contacts operating in a vacuum atmosphere and it is specifically designed for quenching the electric arcs arising when the current flowing along the electric pole is interrupted
Implementation Method 2
Some load-break switches have been developed, in which electric poles are immersed in pressurized dry air or other environment-friendly insulation gases
Data Source
AI summary
A switching apparatus including one or more electric poles. For each electric pole, the switching apparatus includes a first pole terminal, a second pole terminal, and a ground terminal. The switching apparatus further includes a plurality of fixed contacts spaced apart one from another, a movable contact, which is reversibly movable about a corresponding rotation axis according to opposite first and second rotation directions, so that said movable contact can be coupled to or uncoupled from one or more of the above-mentioned fixed contacts, a vacuum interrupter including a vacuum chamber, in which a fixed arc contact and a movable arc contact are enclosed and can be coupled or separated, and a motion transmission mechanism operatively coupled to the movable arc contact of said vacuum interrupter.