Adjustable Magnetic Yoke Assembly for Short-Circuit Contact Force
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Solution Overview
Problem
Existing electromechanical switching devices struggle to handle high current short-circuits due to the inability of traditional ferromagnetic yokes with static functional gaps to dynamically adjust contact force, leading to performance trade-offs between short-circuit withstand and current interruption.
Innovation Solution
A dynamic adjustable magnetic yoke assembly with collapsible bias members, such as springs or break-away structures, adjusts the functional gap in response to current levels, ensuring high contact force during short-circuits and low force during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a static functional gap is used in the magnetic yoke assembly, then the device structure is simple and manufacturing is easy, but the short-circuit withstand performance is insufficient because the contact force cannot be dynamically increased
Solution Approach 1:
The magnetic yoke assembly transitions from a static structure to a dynamic one by introducing collapsible bias members (springs) that allow the functional gap to change dynamically. During normal operation, the springs maintain a larger gap for optimal current interruption. During short-circuit conditions, the increased magnetic force compresses the springs, reducing the gap and increasing contact force to prevent contact separation and withstand the short-circuit current.
Solution Approach 2:
The invention changes the physical parameter of the functional gap size based on operating conditions. By using collapsible bias members, the gap size is no longer fixed but varies with the applied current. At normal current levels, the gap remains larger for efficient current interruption. At short-circuit current levels, the gap reduces as the bias members collapse, thereby increasing the magnetic attraction force between the yokes to prevent contact levitation.
2Reliability
If a static functional gap is used to increase contact force during short-circuit, then short-circuit withstand performance improves, but current interruption capability deteriorates due to excessive contact force
Solution Approach 1:
The dynamic nature of the magnetic yoke assembly allows it to adapt its characteristics to different operating modes. During current interruption, the springs maintain a larger functional gap that reduces magnetic attraction, enabling faster and more effective contact separation. During short-circuit conditions, the same springs collapse under increased magnetic force, reducing the gap and increasing contact force to prevent contact separation. This dynamic adaptation resolves the contradiction between needing high contact force for short-circuit withstand and low contact force for current interruption.
3Reliability
If the functional gap is reduced to increase contact force, then short-circuit withstand performance improves, but the device complexity increases due to additional components
Solution Approach 1:
The collapsible bias members (springs) serve multiple functions simultaneously: they provide the mechanical force to maintain the functional gap during normal operation for current interruption, they allow dynamic adjustment of the gap during short-circuit conditions, and they act as energy storage elements. This multi-functionality reduces the need for additional separate components, making the increased complexity worthwhile by achieving both improved short-circuit withstand performance and maintained current interruption capability.
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 dynamic adjustable magnetic yoke assembly enhances short-circuit withstand performance without compromising current interruption capabilities by optimizing the functional gap based on current levels.
Implementation Method 1
The yokes are physically separated by a functional gap where an attractive magnetic field is generated in response to electrical current in the current-carrying members
Implementation Method 2
making use of ferromagnetic yokes with a functional gap that dynamically adjusts
Implementation Method 3
the one or more collapsible bias members include one or more springs
Data Source
AI summary
Electromechanical switching devices and methods of manufacturing electromechanical switching devices that include a dynamic adjustable magnetic yoke assembly are disclosed. In a particular embodiment, an electromechanical switching device includes a moveable contact, one or more magnetic upper yokes provided above the moveable contact and separate from the moveable contact, a magnetic lower yoke provided below the moveable contact, and one or more collapsible bias members supporting the upper yoke.