Electromagnetic Relay Arc Cutoff Stability
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Solution Overview
Problem
Electromagnetic relays struggle to stably cut off arcs in high-voltage DC circuits due to instability in arc extinguishing, particularly when the arc path space is limited between the contact spring and the case.
Innovation Solution
The design includes a stretch space beyond the tips of the fixed and moving contact holders, with magnets generating a Lorentz force to stretch the arc, ensuring it reaches the opposite surfaces of the holders, allowing for effective arc extension and stable cutoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the arc path space is provided between the end of the contact spring and the case, then the arc can be stretched laterally, but the arc cannot be cut off stably in high-voltage DC circuits
Solution Approach 1:
The invention transitions from lateral arc stretching (horizontal dimension) to longitudinal arc stretching (vertical dimension along the contact holder). The stretch space is formed along the length of the contact holder, extending the arc in the direction of the holder's axis rather than laterally across the contact spring width. This dimensional change enables stable arc cutoff in high-voltage DC circuits.
Solution Approach 2:
The invention introduces a magnetic field as an intermediary to control arc behavior. Magnets are positioned to generate a magnetic field that interacts with the arc current, forcing the arc to stretch along the contact holder toward the tip. This magnetic field mediator enables reliable arc extension and cutoff without requiring large physical gaps or complex mechanical structures.
2Area of stationary object
If the arc is stretched laterally along the width of the contact spring, then the arc path space can be utilized, but the contact holder length is insufficient for effective arc extension
Solution Approach 1:
The invention shifts the arc stretching direction from lateral (width direction) to longitudinal (length direction) along the contact holder. This allows the full length of the contact holder to be utilized for arc extension, maximizing the available space for arc cutoff while maintaining a compact lateral footprint.
Solution Approach 2:
The invention changes the orientation and configuration of the magnetic field to produce Lorentz force that directs the arc along the contact holder's length. By adjusting the magnetic field parameters (strength, direction, distribution), the arc is forced to extend toward the tip of the contact holder, effectively utilizing the holder's length for arc extension.
3Reliability
If magnets are used to generate Lorentz force for arc stretching, then the arc can be extended along the contact holder, but additional components are introduced
Solution Approach 1:
The magnets serve multiple functions: they generate the magnetic field for arc control, provide structural positioning elements, and can be integrated with the contact holder assembly. This multi-functionality reduces the need for separate arc control mechanisms, offsetting the added component count with consolidated design benefits.
Solution Approach 2:
The magnetic field generation system is designed to be self-regulating, where the Lorentz force automatically adjusts based on the arc current magnitude and position. The system uses the arc's own current to generate the force needed for stretching, eliminating the need for external power sources or complex control circuits.
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 configuration enhances the stability and reliability of arc cutoff in high-voltage DC circuits by extending the arc length sufficiently, reducing the risk of arc shorting and improving the durability of the relay contacts.
Implementation Method 1
Magnetic field generation means for generating a magnetic field in the arc extension space, thereby stretching an arc, generated when the movable contact point approaches to and is separated from the stationary contact point, along a predetermined direction by the magnetic field
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided herein is an electromagnetic relay with improved ability to cut off an arc with stability. An electromagnetic relay (1) includes a fixed contact holder (12), a moving contact holder (14), an electromagnetic device (A10), and a magnet (17, 18). The fixed contact holder (12) extends in a predetermined direction and is provided with a fixed contact (11). The moving contact holder (14) also extends in the predetermined direction, and is provided with a moving contact (13). The magnet (17, 18) is arranged perpendicularly to an opening/closing direction of the fixed contact (11) and the moving contact (13). A stretch space (E1) in which an arc generated between the fixed contact (11) and the moving contact (13) is stretched is provided, in the predetermined direction, beyond respective tips of the fixed contact holder (12) and the moving contact holder (14). The stretch space (E1) also faces a surface (12b) of the fixed contact holder (12) and a surface (14b) of the moving contact holder (14).