Gas-Insulated Switching Device Intermediate Pressure Compartment
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Solution Overview
Problem
In gas-insulated switching devices for power transmission and distribution grids, the use of SF6 gas is restricted due to its high global warming potential, and its substitutes like dry air, CO2, or N2 require increased pressure, which puts stress on the bellows and insulation support bodies, especially when vacuum valves are operated, as they need to withstand impact while maintaining airtightness.
Innovation Solution
A gas-insulated switching device design where the internal space of the bellows and an airtight container communicate, forming an intermediate pressure compartment, with airtight container members sliding to absorb impact and reduce stress on the insulation support body, which is connected to the tank wall via an insulation support body, allowing the insulation support body to focus on structural strength rather than airtightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tank inside pressure is increased to substitute SF6 gas with low global warming potential gases, then the insulation performance is improved, but the bellows is subjected to greater difference pressure and requires increased strength
Solution Approach 1:
The internal space of the bellows is divided into multiple compartments with different pressure levels. The first compartment is at vacuum pressure, the second compartment is at intermediate pressure, and the third compartment is at tank inside pressure. This segmentation reduces the difference pressure across the bellows walls, allowing the use of lower strength materials while maintaining insulation performance at high tank pressure.
Solution Approach 2:
A partition wall with a through-hole is introduced as an intermediary structure between the vacuum chamber and the high-pressure tank interior. This partition creates an intermediate pressure compartment that mediates the pressure transition, reducing the stress on the bellows while maintaining the vacuum environment needed for the circuit breaker operation.
2Device complexity
If the vacuum valve is fixed directly to the tank wall via the insulation support body, then the structure is simplified, but the insulation support body must withstand impact while ensuring airtightness, requiring increased strength and complexity
Solution Approach 1:
The airtight container is extracted from the insulation support body structure. The vacuum valve is fixed to the airtight container, which is then connected to the insulation support body through a sliding connection. This separation allows the insulation support body to focus on providing structural strength and the airtight container to maintain the intermediate pressure environment, reducing the strength requirements for the insulation support body.
Solution Approach 2:
The connection between the airtight container and the insulation support body is made dynamic through a sliding mechanism rather than a fixed rigid connection. This dynamic connection allows the airtight container to move independently to absorb impact forces during vacuum valve operation, reducing the transmission of impact to the insulation support body while maintaining airtightness.
3Strength
If the airtight container is made rigid to withstand impact, then the impact resistance is improved, but the airtightness may be compromised and the structure becomes more complex
Solution Approach 1:
The airtight container is constructed with flexible components including a bellows structure and elastic airtight seal members. These flexible elements can deform to absorb impact forces while maintaining the airtight seal. The bellows allows volumetric changes during impact events, and the elastic seal members maintain contact to preserve airtightness despite the flexible construction.
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 design suppresses the propagation of impact during vacuum valve operation, enhancing the reliability of the intermediate pressure compartment and improving insulation performance while reducing the need for high-strength bellows and support structures.
Implementation Method 1
a vacuum valve having, in a vacuum, a movable contact provided on one side of a movable conductor
Implementation Method 2
the first airtight container member and the second airtight container member are slidable with each other in a movable direction of the movable conductor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A gas-insulated switching device (1) including, inside a pressure tank (4): a vacuum valve (11) having, in a vacuum, a movable contact (14) provided on one side of a movable conductor (12), and a fixed contact (15) provided to a fixed conductor (13); an insulation rod (23) connected to another side of the movable conductor (12) led out through a bellows (16) from the vacuum valve (11); and an airtight container (36) in which the insulation rod (23) and the other side of the movable conductor (12) are stored, wherein an internal space of the bellows (16) and an internal space of the airtight container (36) communicate with each other, one side of the vacuum valve (11) is fixed to a tank wall (10) of the pressure tank (4) via an insulation support body (22), another side of the vacuum valve (11) is connected to the tank wall (10) via the airtight container (36), and the airtight container (36) insulates the vacuum valve (11) and the tank wall (10) from each other, and is slidable in a movable direction of the movable conductor (12).