Switchgear Arc Control via Magnetic Side Face Inversion
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Solution Overview
Problem
Conventional switchgears face reliability issues when reversing current direction due to arc extension problems, leading to increased size requirements and potential accidents, as magnetic field lines and Lorentz forces act unpredictably, making it difficult to maintain interruption reliability with miniature magnets.
Innovation Solution
A switchgear design where the arc is driven along the side face of an attraction bar, allowing for quick cooling and maintaining high interruption reliability without increasing size, using a compact configuration with a permanent magnet and magnetic reinforcing plate to control the arc's direction and extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the arc-extinguishing space is increased to maintain interruption reliability when current direction is reversed, then interruption reliability is improved, but the switchgear size is increased
Solution Approach 1:
Instead of allowing the arc to extend freely in the conventional direction, the invention inverts the approach by using magnetic field lines to drive the arc along the side face of the attraction bar toward the magnet. This reversed arc extension path enables reliable current interruption without requiring increased switchgear size, as the arc is contained within a compact space while still achieving sufficient extension for interruption.
2Reliability
If a magnetic yoke is used to form magnetic field lines outside the face facing the permanent magnet, then the Lorentz force acts more effectively, but the switchgear size is increased
Solution Approach 1:
The invention extracts the essential function of arc control by utilizing the side face of the attraction bar as the primary surface for arc extension, rather than relying on a complete magnetic yoke structure. This selective approach maintains the necessary magnetic field interaction while removing unnecessary structural components, thereby achieving reliable interruption without increasing switchgear size.
3Reliability
If the magnetic pole face is widened to make magnetic field lines intersect the arc uniformly, then interruption reliability is improved, but structural costs are increased
Solution Approach 1:
Instead of widening the entire magnetic pole face uniformly, the invention applies magnetic field interaction locally at the side face of the attraction bar. The magnetic field lines are concentrated where they are most effective for arc extension, eliminating the need for costly uniform pole face widening while maintaining interruption reliability.
4Volume of moving object
If a miniature magnet is used to reduce size, then switchgear size is reduced, but interruption reliability deteriorates due to unpredictable magnetic field lines
Solution Approach 1:
The invention introduces asymmetry by positioning the magnet and attraction bar such that magnetic field lines interact with the arc in a specific asymmetric pattern along the side face. This asymmetric configuration ensures predictable arc extension behavior even with a miniature magnet, maintaining interruption reliability while achieving compact 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
The solution ensures reliable current interruption regardless of current direction, enhancing interruption reliability and reducing structural costs by maintaining a compact design, even with miniature magnets, while effectively managing arc extension and cooling.
Implementation Method 1
magnetic field lines from a permanent magnet are conventionally made to intersect the arc
Implementation Method 2
the Lorentz force is made to act on the arc, whereby the arc is extended
Implementation Method 3
the arc runs toward the magnet and is extended, while driven along the side face of the attraction bar, the arc is quickly cooled
Data Source
Figure 1
Figure 2(I)~2(V)
Figure 3~4
AI summary
A switchgear (100) is provided with a switch mechanism (103) that can connect or disconnect a movable contact (2a) to/from a fixed contact (1a); a magnet (4) that generates a magnetic field for extending an arc generated when the contacts (1a) and (2a) separate; and an elongated magnetic body (3), one end of which is in contact with a magnetic pole face of the magnet. The other end of the magnetic body (3) is disposed near an arc-generating area between the fixed contactor (1) and the movable contactor (2), and the magnetic field generated by the magnet (4) extends the arc along a longitudinal side face of the magnetic body (3).