DC Air Circuit Breaker Arc-Extinguishing Structure for Arc Backflow Control
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Solution Overview
Problem
Existing direct-current air circuit breakers face issues with arc stagnation and structural damage due to small current interruptions, leading to performance deterioration and equipment accidents, as the generated magnetic field-based driving force is insufficient for quick arc extinguishing.
Innovation Solution
An arc-extinguishing structure for direct-current air circuit breakers that utilizes magnets with vertically arranged upper and lower poles to generate a strong magnetic field, guiding the arc to an extinguishing unit and preventing reverse flow, enhancing the arc magnetic field-based driving force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional arc extinguishing structure is used in direct-current air circuit breakers, then the structure is simple, but arc stagnation occurs between contacts during small current interruptions due to insufficient magnetic field-based driving force
Solution Approach 1:
A magnet is introduced as an intermediary component between the arc and the cooling plate to generate a magnetic field that enhances the magnetic field-based driving force. This mediator enables effective arc discharge even during small current interruptions where the natural magnetic field would be insufficient, preventing arc stagnation without fundamentally redesigning the entire extinguishing structure
Solution Approach 2:
The magnetic field strength parameter is enhanced by introducing a magnet with specific magnetic properties. This parameter change increases the magnetic field-based driving force acting on the arc, enabling reliable arc extinguishing during small current interruptions while maintaining the basic structure of the extinguishing chamber and cooling plate
2Reliability
If the magnetic field-based driving force is increased to prevent arc stagnation, then arc extinguishing performance improves, but the risk of arc reverse flow increases
Solution Approach 1:
The magnet is positioned asymmetrically closer to the arc generation region rather than at the center of the cooling plate. This asymmetric positioning creates a stronger magnetic field in the arc discharge direction while maintaining sufficient field strength to prevent reverse flow, optimizing the magnetic field distribution to achieve both arc extinguishing and reverse flow prevention
Solution Approach 2:
The magnetic field strength is made non-uniform by positioning the magnet closer to the arc region, creating a locally stronger magnetic field where it is most needed for arc discharge. This local quality enhancement ensures effective arc extinguishing while the field gradually decreases toward the cooling plate, preventing excessive force that could cause reverse flow
3Speed
If the magnet is positioned closer to the arc to maximize magnetic field-based driving force, then arc discharge speed improves, but arc reverse flow may occur
Solution Approach 1:
The magnet is positioned asymmetrically at an optimized distance from the arc rather than at the center of the cooling plate. This asymmetric positioning creates a gradient in magnetic field strength that is strongest near the arc for rapid discharge but decreases toward the cooling plate, preventing excessive force that would cause reverse flow while maintaining high discharge speed
4Reliability
If the magnet size is increased to maximize magnetic field magnitude, then arc magnetic field-based driving force is maximized, but device complexity and space requirements increase
Solution Approach 1:
The magnetic field strength is optimized by selecting a magnet with specific parameters (size, material, positioning) rather than simply increasing size indefinitely. This parameter optimization achieves the required magnetic field-based driving force for reliable arc extinguishing while maintaining compact dimensions suitable for integration into the circuit breaker structure
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 structure ensures rapid arc extinguishing and prevents arc backflow, maintaining equipment integrity and improving small current interruption performance by maximizing the magnetic field magnitude.
Implementation Method 1
an arc magnetic field-based driving force using a magnetic field of a magnet
Implementation Method 2
an arc as generated travels from the fixed contact and the movable contact to a cooling plate via a Lorentz force (an arc magnetic field-based driving force) generated orthogonally by arc current and a magnetic flux density
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An arc-extinguishing unit structure for a direct current air circuit breaker according to one embodiment of the present disclosure comprises: a plurality of grids; side plates coupled to both sides of the plurality of grids so that the plurality of the grids are mounted so as to be spaced apart from each other; an exhaust cover positioned above the side plates and the plurality of grids; an arc guide coupled to the side plates so as to be located under the plurality of grids; a magnet coupled to the arc guide, wherein the magnet is magnetized with different poles on the basis of the plurality of grids and the vertical orientation of the arc guide.