Floating Magnetic Conductor Contactor for Short-Circuit Withstand
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Solution Overview
Problem
High-voltage DC contactors face limitations in withstanding surge currents and short-circuit currents, leading to potential failure and incorrect operation due to strong electric repulsion forces, and existing improvements compromise the ability to connect and disconnect currents effectively.
Innovation Solution
A contactor design featuring a pair of static terminals, a movable terminal, first and second magnetic conductors, and an elastic member, where the second magnetic conductor is floatably supported and arranged to decrease distance with increasing current, enhancing electromagnetic attraction to handle high currents, and magnetic blowing magnets are used to extinguish electric arcs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact structure is improved to increase the ability to withstand short circuit current, then the short circuit current withstand ability is improved, but the ability to connect and disconnect current decreases
Solution Approach 1:
The patent introduces a movable magnetic conductor that can dynamically adjust its position based on current magnitude. During normal operation, the magnetic conductor is positioned to facilitate smooth contact making and breaking. During short circuit conditions, the increased current generates stronger electromagnetic attraction that pulls the movable magnetic conductor closer to the static magnetic conductor, increasing the electromagnetic force to withstand the short circuit current. This dynamic positioning resolves the contradiction by adapting the contact structure to different operational conditions.
Solution Approach 2:
The patent changes the electromagnetic field parameters by introducing a movable magnetic conductor whose position varies with current magnitude. The distance between the movable and static magnetic conductors is not fixed but changes based on the current level, allowing the system to optimize electromagnetic attraction force dynamically. This parameter change enables the contactor to handle both normal operation and short circuit conditions effectively.
2Reliability
If the electromagnetic attraction is increased to withstand surge currents, then the short circuit current withstand ability is improved, but the contactor may fail to operate correctly under normal conditions
Solution Approach 1:
The movable magnetic conductor provides dynamic adjustment of electromagnetic attraction force. During normal operation, the magnetic conductor maintains a position that allows reliable contact making and breaking without excessive attraction. When surge currents occur, the increased current generates stronger electromagnetic force that moves the magnetic conductor to a position that provides the necessary attraction to withstand the surge. This dynamic response ensures both normal operation reliability and surge current withstand ability.
Solution Approach 2:
The elastic member pre-positions the movable magnetic conductor at an optimal distance from the static magnetic conductor before current flow begins. This preliminary positioning ensures that during normal operation, the electromagnetic attraction is sufficient for reliable contact but not excessive to cause operational failures. The pre-established equilibrium position prevents both insufficient attraction and excessive attraction issues.
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 increases the contactor's ability to withstand short-circuit currents while maintaining normal connection and disconnection operations by adjusting electromagnetic attraction based on current levels and using magnetic blowing magnets to manage electric arcs, thereby preventing failure from surge currents.
Implementation Method 1
a magnetic blowing magnet arranged in the arc extinguishing chamber and stationary relative to the static terminal... a magnetic field intensity generated by the magnetic blowing magnet itself at the contact end of the static terminal adjacent to the magnetic blowing magnet is higher than a predetermined magnetic field intensity, in order to extinguish an electric arc between the movable terminal and the static terminal through magnetic blowing
Implementation Method 2
when the coil of the contactor is energized, the main contact of the contactor is in a closed state... when the coil of the contactor deenergized, the main contact of the contactor is in an opened state
Implementation Method 3
an elastic member which is provided between the static bracket and the second magnetic conductor. The second magnetic conductor and the static terminal are arranged at the same side of the movable terminal, and the second magnetic conductor is floatable supported in the static bracket by the elastic member
Implementation Method 4
When such a large current flows through the movable and static contacts, a strong electric repulsion force (including Lorentz force and Holm force) will be generated in the main contact circuit
Implementation Method 5
the second magnetic conductor is floatable supported in the static bracket by the elastic member... adjusting electromagnetic attraction based on current levels
Data Source
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AI summary
The present invention discloses a contactor. The contactor comprises of: an insulation outer housing (20); a pair of static terminals (2) which is provided in the insulation outer housing (20) and stationary relative to the insulation outer housing (20); a movable terminal (1) which is provided in the insulation outer housing (20) and movable between a closed position in contact with the static terminal (2) and an opened position separated from the static terminal (2); a first magnetic conductor (3) which is fixed to the movable terminal (1) to move synchronously with the movable terminal (1); a static bracket (5) which is provided in the insulation outer housing (20) and stationary relative to the insulation outer housing (20); a second magnetic conductor (4) which is movably provided in the static bracket (5); and an elastic member (6) which is provided between the static bracket (5) and the second magnetic conductor (4). The second magnetic conductor (4) and the static terminal (2) are arranged at the same side of the movable terminal (1), and the second magnetic conductor (4) is floatable supported in the static bracket (5) by the elastic member (6), so that the distance between the first magnetic conductor (3) and the second magnetic conductor (4) is inversely proportional to the current flowing through the movable terminal (1) and the static terminal (2). The present invention not only improves the ability of the contactor to withstand the short circuit current, but also does not affect the normal connection and disconnection operation of the contactor.