Arc Extinguishing Grid Structure for Small-Current DC Breaks
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Solution Overview
Problem
Direct current air circuit breakers face challenges in extinguishing arcs generated during small current breaks due to the relatively weak arc power and the absence of a zero point in DC current, leading to difficulties in moving the arc to the arc extinguishing unit and potential contact melting.
Innovation Solution
An arc extinguishing unit with a magnetic field structure that includes side plates, grids, and a grid cover with grid legs extending downward to form an induced magnetic field, guiding the arc to the extinguishing unit, and an air gap to increase pressure, ensuring quick arc movement and extinguishment without excessive design changes or increased space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic body is added to form a magnetic field for arc movement, then arc extinguishing effectiveness is improved, but device complexity and space occupation increase
Solution Approach 1:
The grid leg itself serves as the magnetic body that generates the magnetic field. When current flows through the grid leg, it automatically produces a magnetic field around it according to electromagnetic induction principles, eliminating the need for separate magnetic bodies or magnets. This self-generating magnetic field guides the arc along the grid leg structure without requiring additional components.
Solution Approach 2:
The grid leg performs multiple functions simultaneously: it serves as the arc guidance structure, the current conductor, and the magnetic field generator. By integrating these three functions into a single component, the design avoids adding separate magnetic bodies while maintaining effective arc control through the electromagnetic field generated by the current flowing through the grid leg.
2Reliability
If a magnetic body is added to form a magnetic field for arc movement, then arc extinguishing effectiveness is improved, but the space occupied by the magnetic body increases
Solution Approach 1:
The grid leg generates its own magnetic field through the current flowing through it, eliminating the need for separate magnetic bodies that would occupy additional space. The magnetic field is confined to the immediate vicinity of the grid leg structure itself.
Solution Approach 2:
The magnetic field-generating function is merged with the arc guidance structure. The grid leg that guides the arc is also the conductor that generates the magnetic field, combining what would traditionally be separate components into one integrated structure, thereby minimizing space requirements.
3Loss of energy
If the arc power is weak during small current breaks, then energy loss is reduced, but the arc cannot move to the grid and extinguishing becomes difficult
Solution Approach 1:
The magnetic field strength is concentrated locally around the grid leg where the arc occurs. The current flowing through the grid leg generates a strong localized magnetic field in the immediate vicinity of the arc, providing sufficient electromagnetic force to move even weak arcs caused by small currents along the grid leg path to the extinguishing region.
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 moves and extinguishes arcs in DC air circuit breakers by forming a strong magnetic field and increasing arc pressure, improving arc-guided path efficiency and reducing extinguishing time.
Implementation Method 1
a grid leg extending downward from both ends in the width direction of the grid, so that an induced magnetic field is formed by an arc generated when a fixed contact and a movable contact are spaced apart
Implementation Method 2
The generated arc passes through the extinguishing device, the arc pressure is increased, the moving speed is increased, and it is cooled at the same time and can be discharged to the outside
Data Source
AI summary
Disclosed are an arc extinguishing unit and an air circuit breaker comprising the same. The present disclosure provides an arc extinguishing unit, including: side plates spaced apart from each other and disposed to face each other; a plurality of grids disposed between the side plates, spaced apart from each other, and coupled to the side plates, respectively; and a grid cover located above the grid and covering the grid, wherein the grid includes a grid leg extending downward from both ends in the width direction so that an induced magnetic field can be formed by an arc generated when a fixed contact and a movable contact are spaced apart.