DC Relay Magnetizer Layout for Short-Circuit Arc Extinguishing
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Solution Overview
Problem
DC relays in the prior art fail to provide sufficient contact pressure to resist electro-dynamic repulsion forces caused by large short-circuit currents, making them inadequate for modern applications requiring resistance to high fault currents without burning or exploding, especially at 8000 A in 5 ms, while maintaining a small volume.
Innovation Solution
A DC relay design featuring a straight sheet type movable spring with upper and lower magnetizers forming independent magnetically conductive loops, allowing for increased magnetic pole faces through holes, which generates attraction force to counteract electro-dynamic repulsion forces during fault currents, ensuring high magnetic efficiency and preventing magnetic circuit saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a direct-acting magnetic circuit structure is adopted to maintain small volume, then the relay size is reduced, but the contact pressure is insufficient to resist electro-dynamic repulsion force during short-circuit current
Solution Approach 1:
The magnetic circuit is segmented into multiple independent magnetic loops (first magnetic loop and second magnetic loop) that share common magnetic path portions. This segmentation allows the magnetic flux to be distributed across multiple paths, increasing the overall magnetic force and contact pressure while maintaining a compact structure. The movable iron core is divided into multiple segments (first movable iron core segment, second movable iron core segment) that cooperate with corresponding stationary segments to form the segmented magnetic loops.
Solution Approach 2:
The patent employs a nested magnetic circuit structure where multiple magnetic loops are embedded within each other, sharing common magnetic path portions. The first magnetic loop and second magnetic loop are nested such that they share the yoke and portions of the magnetic circuit, creating a compact nested arrangement that maximizes magnetic force within a small volume while providing sufficient contact pressure.
2Force
If the magnetic circuit is designed to provide sufficient attraction force for short-circuit resistance, then the contact pressure increases, but the magnetic circuit becomes prone to saturation
Solution Approach 1:
The magnetic flux is segmented into multiple independent loops that share common magnetic paths. This segmentation distributes the magnetic flux density across multiple paths, preventing any single path from becoming saturated. Each magnetic loop carries a portion of the total magnetic flux, allowing the overall system to generate high attraction force while maintaining magnetic circuit reliability and avoiding saturation.
Solution Approach 2:
The patent introduces an additional dimensional aspect to the magnetic circuit by creating multiple loops that share common magnetic paths. This multi-loop configuration adds a topological dimension to the magnetic flux distribution, enabling the system to achieve high attraction force through cumulative effect while the shared magnetic paths distribute the flux density to prevent saturation.
3Device complexity
If the relay structure is simplified to maintain small volume, then the manufacturing is easier, but the electro-dynamic repulsion force during short-circuit current cannot be effectively resisted
Solution Approach 1:
The nested magnetic loop structure allows multiple magnetic circuits to be integrated within a compact shared framework. The yoke and magnetic path portions are shared between the first and second magnetic loops, creating a nested configuration that achieves high resistance to electro-dynamic repulsion force without proportionally increasing device complexity. The shared magnetic components reduce the overall structural complexity compared to having completely separate magnetic 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
The design effectively resists short-circuit currents by generating increased contact pressure and attraction force, evenly dividing large currents through independent loops, maintaining high magnetic efficiency and preventing magnetic saturation, thus meeting market requirements for fault current resistance.
Implementation Method 1
at least two independent magnetically conductive loops are formed in the width direction of the movable spring by the upper magnetizers and the lower magnetizers, thus by using magnetic pole faces added to the through holes corresponding to the magnetically conductive loops, when the movable spring has a large fault current, attraction force in a contact pressure direction is generated to resist an electro-dynamic repulsion force generated, due to the fault current between the movable spring and the stationary contact leading-out terminals
Implementation Method 2
at least two independent magnetically conductive loops are formed in the width direction of the movable spring by the upper magnetizers and the lower magnetizers
Implementation Method 3
maintaining high magnetic efficiency and preventing magnetic circuit saturation
Data Source
AI summary
A DC relay having a function of extinguishing arc and resisting short-circuit current includes two stationary contact leading-out terminals, a push rod component, a straight sheet type movable spring mounted on the push rod component and two permanent magnets. Two permanent magnets are respectively arranged on two sides in the width direction of the movable spring. Two permanent magnets have opposite magnetic poles on sides facing to the movable and stationary, and have same magnetic poles on the same side in the width of the movable springs. A yoke clip is connected between two permanent magnets. Upper and lower magnetizers are respectively mounted above and under the position, and can approach or come into contact with each other through the through holes in the movable spring. At least two independent magnetically conductive loops are formed in the width direction of the movable spring by the upper and lower magnetizers.