Electromagnetic Relay Magnet Layout for Fast Arc Extinction
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Solution Overview
Problem
In electromagnetic relays, arcs between fixed terminals can short-circuit, leading to difficulties in quickly extinguishing the arc and deteriorating circuit-breaking performance.
Innovation Solution
The electromagnetic relay design includes outer and inner magnets generating magnetic fields to elongate arcs in specific directions, with optional protrusions and insulating materials to enhance arc extinction, and strategically positioned corners on terminals to control arc direction, ensuring quick extinction even if short-circuiting occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a pair of magnets are disposed outside the fixed contacts to generate a magnetic field for elongating the arc, then the arc extinction speed is improved, but the circuit-breaking performance deteriorates when arc short-circuiting occurs between fixed terminals
Solution Approach 1:
The magnetic field generation system is segmented into two independent magnet assemblies: outer magnets for elongating normal arcs, and inner magnets for elongating short-circuited arcs. This segmentation allows each magnet assembly to be optimized for its specific function without interfering with the other, resolving the contradiction between arc extinction speed and circuit-breaking performance under short-circuit conditions
Solution Approach 2:
The inner magnets act as an intermediary mechanism that specifically addresses the short-circuit arc problem. When arc short-circuiting occurs between fixed terminals, the inner magnets generate a magnetic field that elongates the short-circuited arc, preventing it from maintaining a low-impedance path and thereby preserving circuit-breaking performance
2Length of moving object
If magnets are positioned to elongate arcs in the longitudinal direction of the movable plate, then arc elongation is achieved, but short-circuited arcs between fixed terminals cannot be effectively elongated
Solution Approach 1:
The magnetic field generation is extended from a single longitudinal dimension to multiple dimensions. Outer magnets generate magnetic fields in the longitudinal direction of the movable plate for normal arc elongation, while inner magnets generate magnetic fields in the direction intersecting with the longitudinal direction for short-circuited arc elongation. This multi-dimensional approach ensures effective arc elongation regardless of arc orientation
Solution Approach 2:
Different regions of the relay are equipped with magnets having different orientations and field characteristics. The outer magnets are positioned and oriented for optimal performance with normal arcs, while the inner magnets are specifically positioned between the fixed terminals and oriented to effectively elongate short-circuited arcs. This local optimization ensures that each magnet assembly addresses the specific arc conditions in its 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
This design effectively reduces the deterioration in breaking performance by quickly extinguishing arcs, ensuring reliable circuit operation.
Implementation Method 1
The outer magnet generates a magnetic field to elongate an arc generated between the first fixed contact and the first movable contact and between the second fixed contact and the second movable contact
Implementation Method 2
The inner magnet generates a magnetic field to elongate the arc in a third direction
Implementation Method 3
The Lorentz force acting on the arc by the magnet elongates the arc, thereby rapidly extinguishing the arc
Data Source
AI summary
An electromagnetic relay includes a first fixed terminal, a first fixed contact, a second fixed terminal, a second fixed contact, a first movable contact, a second movable contact, a movable contact piece, a drive device, an outer magnet, and an inner magnet. The second fixed terminal is disposed apart from the first fixed terminal in a first direction. The first movable contact and the second movable contact are disposed to face the first fixed contact and the second fixed contact, respectively, in a second direction. The outer magnet generates a magnetic field to elongate an arc generated between the first fixed contact and the first movable contact and between the second fixed contact and the second movable contact. The inner magnet generates a magnetic field to elongate the arc in a third direction.