Switch Blade Slits for Multi-Point Contact
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Solution Overview
Problem
In gas-insulated switchgear, disconnector and grounding switches face issues with high contact-pressure loads leading to arcing, welding, and mechanical wear, requiring complex assembly and reducing reliability due to the high electromagnetic forces generated during large current flows.
Innovation Solution
A switch design with slits in the conductive contact surfaces and a thinner contact-pressure spring fixing portion to achieve multi-point contact, reducing the contact-pressure load and enhancing the mechanical and electrical connection between the blade and fixed contactors, allowing for smoother operation and reduced wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large contact-pressure spring load is applied to prevent arcing and welding, then the reliability during closed circuit operation is improved, but the mechanical wear due to sliding increases and the operation device load increases
Solution Approach 1:
The contact surface of the blade is divided into multiple contact points by providing slits. This segmentation distributes the contact pressure across multiple points, reducing the load on each individual contact point while maintaining sufficient total contact pressure to prevent arcing and welding. The slits create a multi-point contact structure that reduces sliding wear at each point.
2Reliability
If a large contact-pressure spring load is applied to prevent arcing and welding, then the reliability during closed circuit operation is improved, but the load on the operation device increases
Solution Approach 1:
The contact surface is segmented into multiple contact points through slits, distributing the electromagnetic force and contact pressure across these points. This reduces the force that the operation device must overcome during opening and closing operations while maintaining sufficient total contact pressure for reliable operation.
Solution Approach 2:
The blade thickness at the contact portion is reduced to decrease the moment of inertia and reduce the operational load on the operation device. This parameter change allows the blade to be more easily moved while the multi-point contact structure maintains sufficient electrical contact pressure.
3Ease of operation
If the blade thickness is reduced to reduce operational load, then the ease of operation is improved, but the strength at the contact portion decreases
Solution Approach 1:
The blade has different thicknesses at different locations: thinner at the contact portion for ease of operation and lighter weight, and thicker at the rotation center portion for structural strength. This local quality variation optimizes both operational ease and structural integrity.
Solution Approach 2:
The contact surface is segmented into multiple contact points by slits, which distributes the stress and electromagnetic forces across these points. This allows the blade to be thinner overall while maintaining sufficient strength at the contact portion through the distributed contact structure.
4Device complexity
If manual assembly is used, then the device complexity is reduced, but the manufacturing precision decreases due to inability to compress springs
Solution Approach 1:
The contact-pressure springs are pre-compressed to generate the required contact pressure before assembly. This preliminary action allows the springs to be installed in a relaxed state and then compressed to the correct tension during assembly, enabling manual assembly while maintaining manufacturing precision.
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 contact-pressure loads, improves switch reliability, and extends the switch's lifespan by distributing the load evenly and minimizing mechanical wear, enabling smoother opening and closing operations.
Implementation Method 1
a contact-pressure spring load that is larger than the electromagnetic force
Implementation Method 2
as a large current flows, electromagnetic force is generated, which may open the contact part between the blade and the fixed contactor
Data Source
Figure 1(a)~1(c)
Figure 2(a)~3(b)
Figure 4
AI summary
In a switch in which one end portion (EP) of a blade (2) is pivotally attached to a fixed contactor (1a) in a pressure contact state and another end portion (EF) of the blade (2) is brought into pressure contact with a fixed contactor (1b) by rotational operation of the blade (2), at least one slit (8) is provided in each of a conductive contact surface, with respect to the fixed contactor (1a), of the one end portion (EP) of the blade (2) and a conductive contact surface, with respect to the fixed contactor (1b), of the other end portion (EF) of the blade (2), so as to divide each of the conductive contact surfaces, thereby achieving multi-point contact on each of the conductive contact surfaces, and a thickness of a contact-pressure spring fixing portion (EC) of the blade (2) at which a contact-pressure spring (3b) for bringing the other end portion (EF) into pressure contact with the fixed contactor (1b) is made smaller than that of the other end portion (EF).