Electromagnet Contact Device Magnetic Yoke Short Circuit Force
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Solution Overview
Problem
Conventional contact devices face issues with short circuits causing reduced pressing pressure between contacts, leading to potential arc generation and welding due to electromagnetic repulsive forces.
Innovation Solution
Incorporating a magnetic yoke between the movable and fixed contacts to balance the magnetic field, ensuring the downward electromagnetic force exceeds the upward force, effectively canceling out repulsive forces and maintaining contact pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional contact device is used without a magnetic yoke, then the structure is simpler, but the pressing pressure between contacts is reduced during short circuit conditions due to electromagnetic repulsive forces
Solution Approach 1:
A magnetic yoke is introduced as an intermediary component between the coil and the movable contact. The yoke serves as a magnetic flux conductor that redirects the magnetic field paths, creating a downward electromagnetic force that counteracts the upward repulsive force generated during short circuit conditions. This mediator component stabilizes the contact pressure without requiring fundamental changes to the basic contact device structure.
Solution Approach 2:
The magnetic yoke generates a downward electromagnetic force that acts as a counterweight to the upward electromagnetic repulsive force that occurs during short circuits. By positioning the yoke to create an opposing force, the system balances the net force on the movable contact, preventing pressure reduction and maintaining stable contact during abnormal operating conditions.
2Object-affected harmful factors
If no magnetic yoke is provided, then the device complexity is lower, but arc generation and welding may occur due to reduced pressing force under short circuit conditions
Solution Approach 1:
The magnetic yoke acts as an intermediary that modifies the magnetic field distribution to prevent harmful effects. By redirecting magnetic flux through the yoke, the system generates a stabilizing downward force that maintains adequate contact pressure, thereby preventing arc generation and welding during short circuit conditions without adding complex active control systems.
Solution Approach 2:
The magnetic yoke provides preliminary counter-action by continuously generating a downward electromagnetic force that preemptively counteracts the upward repulsive force before it can cause contact separation. This preventive mechanism ensures contact pressure is maintained throughout the short circuit event, preventing arc generation and welding before they can occur.
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 effectively suppresses the reduction of pressing force between contacts, preventing arc generation and welding, even under short circuit conditions.
Implementation Method 1
the downward electromagnetic force exceeds the upward force, effectively canceling out repulsive forces and maintaining contact pressure
Data Source
AI summary
An electromagnet device is configured to generate a magnetic attractive force between a stationary core and a movable core when electricity is applied to a coil, so that the movable core is moved in a direction for coming into contact with the stationary core, and a movable shaft is moved in a direction in which a first end face of the movable shaft separates from a movable terminal. After the movable contact comes in contact with the fixed contact, the movable core moves further in a direction for coming into contact with the stationary core. A yoke made of a magnetic body is disposed between the movable terminal and the first end of the movable shaft.