High Voltage Vacuum Interrupter with Cushion Spring and Hydrophobic Vent
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Solution Overview
Problem
High voltage vacuum interrupters rely on insulating mediums like SF6 gas, oil, or nitrogen to prevent electrical flashovers, which have global warming potential and leak issues, and braze joints face tension stresses during operation, leading to potential failures.
Innovation Solution
The use of atmospheric air as the insulating medium within the vacuum interrupter housing, facilitated by an air-permeable membrane that prevents liquid ingress and condensation, combined with a cushion spring assembly to maintain vacuum bottles in compression, eliminating tension on braze joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating mediums like SF6 gas, oil, or nitrogen are used to prevent electrical flashovers, then insulation performance is improved, but global warming potential and gas leak risks increase
Solution Approach 1:
The patent extracts and eliminates harmful insulating mediums (SF6 gas, oil, nitrogen) from the system by using vacuum as the insulating medium instead. This removes the source of global warming potential and gas leak risks while maintaining insulation performance through the vacuum environment.
Solution Approach 2:
The patent creates an inert environment by using vacuum as the insulating medium. The vacuum environment provides electrical insulation without the harmful environmental characteristics of traditional insulating mediums, effectively replacing them with a harmless inert atmosphere.
2Ease of operation
If vacuum bottles are stressed due to tension during contact operation, then operational function is achieved, but braze joints may fail
Solution Approach 1:
The patent applies a counterweight principle by using a compression spring to apply continuous compressive force on the vacuum bottle. This counteracts the tensile stress that occurs during contact operation, ensuring the braze joints remain under compression rather than tension, thereby preventing joint failure.
Solution Approach 2:
The compression spring provides beforehand cushioning by pre-loading the vacuum bottle in compression. This preparatory compressive stress cushions the braze joints against the tensile stresses that will occur during subsequent operational cycles, preventing stress-related failures.
3Reliability
If insulating tube is sealed to prevent water ingress, then electrical insulation is maintained, but condensation may still occur on cold vacuum bottle surfaces
Solution Approach 1:
The patent extracts moisture from the system by using vacuum as the insulating medium. The vacuum environment inherently prevents water vapor condensation on cold surfaces because there is no water vapor present to condense, eliminating the condensation problem while maintaining electrical insulation.
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
This solution prevents electrical flashovers, reduces the risk of gas leaks, and ensures braze joints are not subjected to tensile loads, enhancing the reliability and safety of high voltage switches by using ambient air and cushion springs to manage pressure and stress.
Implementation Method 1
The membrane allows water vapor to flow in or out of the insulating tube
Implementation Method 2
an air permeable membrane that is inherently liquid repellent. The membrane allows air to flow but prevents water and other liquids from entering
Implementation Method 3
a cushion spring assembly to maintain vacuum bottles in compression, eliminating tension on braze joints
Data Source
AI summary
A vacuum interrupter for a high voltage air break switch is disclosed. The interrupter has a plurality of load interrupter contacts enclosed in axially aligned vacuum bottles, each bottle containing a fixed contact and a second contact movable axially away from the fixed contact to open position and toward the fixed contact to closed position. The bottles are positioned in an tubular housing of dielectric material having a top end member and a bottom end member. The vacuum bottles are mechanically coupled to one another in a stack with the top bottle supported by the top end member. At least one air permeable hydrophobic vent member is operatively disposed in the top end member and/or bottom end member and/or tubular housing to prevent condensation in the housing. The stack of vacuum bottles are axially supported at the bottom by a cushion spring assembly keeping the bottles in compression to prevent tension loads on the braze joints of the bottles.