Three-Position Switch Structure for Arc-Resistant Grounding Isolation
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Solution Overview
Problem
Conventional SF6 gas-insulated circuit breakers face issues with environmentally-friendly alternatives having lower arc extinguishing and insulating performance, leading to long pre-breakdown times, arc ablation of contacts, and increased resistance, which affect the flow capacity and insulating performance.
Innovation Solution
A three-position switch design with separate moving isolating and grounding contacts, using insulating guide sleeves and spring contact fingers, along with a crank slider structure and petal-like self-elastic contact, to ensure reliable contact and insulating performance, and a gas box housing the switch with a vacuum arc-extinguishing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If environmentally-friendly gas is used to replace SF6 gas, then environmental protection is improved, but arc extinguishing performance and insulating performance deteriorate
Solution Approach 1:
The patent divides the contact structure into separate moving isolating contact and moving grounding contact, each with dedicated support seats and insulating guide sleeves. This segmentation allows independent optimization of each contact's performance characteristics, enabling the grounding contact to handle arc extinction separately from the isolating contact, thus improving arc extinguishing performance while using environmentally-friendly gas.
Solution Approach 2:
The patent introduces a vacuum arc-extinguishing chamber as an intermediary component to handle the arc extinction function. By placing the arc extinction process in a vacuum environment rather than relying solely on the environmentally-friendly gas, the system achieves both environmental protection and reliable arc extinguishing performance through the vacuum medium's superior arc quenching capabilities.
2Reliability
If SF6 gas-insulated rotary-blade three-position switch is used, then insulating performance is improved, but contact ablation and resistance increase due to long arc time
Solution Approach 1:
The patent separates the isolating contact and grounding contact into independent components with separate support seats (isolating support seat and grounding support seat). This segmentation allows the grounding contact to be optimized specifically for arc extinction while the isolating contact maintains insulating performance, preventing the contact ablation issues that occur in integrated rotary-blade designs where both functions share a common moving contact.
Solution Approach 2:
The vacuum arc-extinguishing chamber serves as an intermediary that handles the arc extinction function, protecting the main contacts from direct arc exposure. This reduces contact ablation and resistance increase, as the vacuum chamber contains and extinguishes the arc away from the critical contact surfaces.
3Productivity
If moving contact blade is lengthened and closing speed is increased to improve closing performance, then closing capacity is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the traditional rotary-blade mechanical switching mechanism with a linear motion system using moving contacts that travel along guided paths defined by insulating guide sleeves. This substitution simplifies the overall structure by eliminating the need for long rotating blades and complex rotary mechanisms, achieving closing capacity through linear actuation rather than rotational motion.
Solution Approach 2:
The patent employs spring contact fingers that provide dynamic contact pressure and self-adjusting characteristics. The spring mechanism automatically compensates for wear and maintains optimal contact force, improving closing capacity without requiring increased closing speed or longer contact blades, thus avoiding the complexity associated with high-speed mechanical systems.
4Reliability
If vacuum arc-extinguishing chamber is added to close grounding short-circuit current, then arc extinguishing performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the vacuum arc-extinguishing chamber functionality directly into the grounding support seat structure. The grounding support seat integrates the vacuum chamber, the moving grounding contact, and the fixed grounding contact into a unified component assembly. This merging approach achieves improved arc extinguishing performance while minimizing device complexity by combining multiple functions into a single integrated structure rather than adding separate components.
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 provides a fast, direct-acting switch with synchronized three-phase operation, reducing contact ablation and maintaining insulating performance, while ensuring reliable grounding and isolating contacts without affecting main circuit flow capacity.
Implementation Method 1
through a first spring contact finger... through a second spring contact finger
Implementation Method 2
connect a vacuum arc-extinguishing chamber in series on a side of a fixed grounding contact, and close the grounding short-circuit current through the arc-extinguishing chamber
Data Source
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AI summary
The present invention discloses a three-position switch. An innovative fast direct-acting three-position switch is used, so that a moving grounding contact is separated from a moving isolating contact, and contact ablation after closing of a grounding short-circuit current does not affect flow of a main circuit, thereby improving closing capacity. During opening, the moving isolating contact and the moving grounding contact are respectively shielded by a shielding cover, and arc ablation of the contact does not affect insulating performance of a clearance. A three-phase moving isolating contact and a three-phase moving grounding contact are simultaneously driven by a transmission shaft, thereby ensuring synchronization of three phases. A linear motion of the moving grounding contact and the moving isolating contact is implemented through rotation of a three-position insulating spindle, and switching of actions such as closing, opening, and grounding of the three-position switch is implemented. The present invention further discloses a gas box using the switch.