Electromechanical Switch With Magnetic Arc-Contact Holding
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Solution Overview
Problem
Existing electromechanical switching devices face challenges in breaking high electric currents due to high separation forces, which can lead to arcing at main contacts and failed current breaking, and increasing the actuating arrangement's power rating results in increased forces, wear, cost, weight, and complexity.
Innovation Solution
The electromechanical switching device incorporates a magnetic member that generates a magnetic holding force in response to current flow through the arcing contacts, counteracting separation forces and maintaining contact between arcing contacts, thereby improving current breaking and commutation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the actuating arrangement's power rating is increased to overcome high separation forces, then the ability to break high currents is improved, but the device's weight, cost, and complexity increase
Solution Approach 1:
A magnetic member is introduced as an intermediary element between the arcing contacts. This magnetic member generates a magnetic holding force that acts as a mediator to counterbalance the electromagnetic separation force, enabling the actuating arrangement to maintain contact under high current conditions without requiring increased power rating or complexity
Solution Approach 2:
The magnetic holding force is adjusted by changing the parameters of the magnetic member (such as magnetic permeability, geometry, or position) to optimize the counterbalancing effect against separation forces across different current levels, allowing reliable operation without oversizing the actuating arrangement
2Reliability
If the actuating arrangement provides higher contact force to maintain arcing contact under high separation forces, then current breaking reliability is improved, but wear and forces on the actuating arrangement increase
Solution Approach 1:
The harmful electromagnetic separation force that tends to pull the arcing contacts apart under high current is converted into a beneficial effect by the magnetic member, which generates an opposing magnetic holding force. This transforms the problem of high separation forces into a balanced force system where the magnetic force compensates exactly for the separation force, reducing the net force requirement on the actuating arrangement
Solution Approach 2:
The magnetic member serves as a force mediator that absorbs and counterbalances the separation force, allowing the actuating arrangement to operate with lower forces while maintaining reliable contact between arcing contacts during high current breaking operations
3Reliability
If the separation distance between arcing contacts is increased to improve current breaking, then arc extinction is improved, but the contact force required to maintain contact decreases
Solution Approach 1:
The magnetic member acts as a force intermediary that compensates for the reduced contact force resulting from increased separation distance. By generating a magnetic holding force proportional to the current, it ensures that even with larger separation distances for better arc extinction, sufficient contact force is maintained to prevent premature contact loss under high current conditions
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 magnetic holding force effectively counteracts separation forces across a wide range of currents, ensuring reliable commutation from main contacts to arcing contacts and preventing arcing at main contacts, thus enhancing the device's ability to break high currents while maintaining a cost-effective design.
Implementation Method 1
a magnetic member arranged to generate a magnetic holding force in response to an electric current flow through the movable arcing contact when the movable arcing contact is in the closed position, the magnetic holding force acting on the movable arcing contact in a direction against the stationary arcing contact
Data Source
AI summary
An electromechanical switching device for breaking an electric current, the switching device including a stationary main contact; a movable main contact; a stationary arcing contact; a movable arcing contact, the stationary arcing contact and the movable arcing contact being arranged in parallel with the stationary main contact and the movable main contact; an actuating arrangement configured to move the movable main contact and the movable arcing contact; and a magnetic member arranged to generate a magnetic holding force in response to an electric current flow through the movable arcing contact when the movable arcing contact is in the closed position, the magnetic holding force acting on the movable arcing contact in a direction against the stationary arcing contact.