Power Switching Apparatus Pressure Tank Insulation
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Solution Overview
Problem
Gas insulated switching apparatuses face challenges in reducing weight and cost while maintaining insulation performance due to high internal gas pressure, necessitating the elimination of current transformer supporting ribs without increasing the size of the bushing and current transformer.
Innovation Solution
A power switching apparatus design featuring a pressure tank with tube-like openings, a vacuum valve, and current transformers installed externally, eliminating the need for supporting ribs by increasing the diameter of the tank openings relative to the current transformer installation portions, and using intermediate bushings with insulating materials to ensure insulation and reduce space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high gas pressure (0.4 to 0.5 MPa-g) is used for insulation, then insulation performance is improved, but device weight and cost increase due to required supporting ribs
Solution Approach 1:
The patent reduces the internal gas pressure from 0.4-0.5 MPa-g to approximately 0.03 MPa-g (30 kPa-g), fundamentally changing the pressure parameter. This pressure reduction eliminates the need for heavy supporting ribs while maintaining insulation performance through increased bushing diameter and optimized electrical clearance distances
Solution Approach 2:
The patent divides the pressure tank structure into segmented regions with different diameter specifications. The bushing opening diameter is increased to 300mm while the current transformer installation portion diameter is reduced to 200mm, creating a stepped configuration that optimizes both insulation and weight
2Ease of operation
If supporting ribs are added to the pressure tank, then current transformer installation is enabled, but device complexity and cost increase
Solution Approach 1:
The bushing opening structure serves multiple functions simultaneously: it provides the necessary insulation clearance, acts as the mounting surface for current transformers, and maintains the reduced-pressure gas seal. This multi-functionality eliminates the need for separate supporting ribs
Solution Approach 2:
The patent moves the current transformer mounting function from the vertical dimension (supporting ribs extending downward) to the horizontal dimension (flanges extending outward from the bushing opening), simplifying the overall structural complexity
3Reliability
If bushing diameter is increased to compensate for pressure reduction, then insulation performance is maintained, but device size and cost increase
Solution Approach 1:
The patent applies different diameter specifications to different functional regions of the bushing. The main bushing opening has a diameter of 300mm for insulation, while the current transformer installation portion has a reduced diameter of 200mm. This localized differentiation maintains insulation performance while minimizing overall device size
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 allows for reduced weight and cost by eliminating the need for supporting ribs, maintaining insulation performance, and enabling easier installation of current transformers, while also enhancing structural strength and reducing the size of the pressure tank and current transformers.
Implementation Method 1
a pressure tank having tube-like openings branched from a shank portion and having an insulating gas sealed therein
Data Source
AI summary
A power switching apparatus includes: a pressure tank having tube-like openings in a shank portion and having an insulating gas sealed therein; a vacuum valve housed in the pressure tank and connected to the pressure tank at one end; bushing conductors penetrating through the openings of the pressure tank and electrically connected to the vacuum valve; and current transformers provided on an outside of the pressure tank and measuring a current flowing through the bushing conductors. Tube-like current transformer installation portions on which to install the current transformers are provided above the openings of the pressure tank and an outside diameter of the openings of the pressure tank is made larger than an outside diameter of the current transformer installation portions.