Contact Bridge Layout for Short-Circuit Repulsion Suppression
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Solution Overview
Problem
Conventional electrical switching devices experience uncontrolled opening of contact elements during high short-circuit currents due to strong repulsion forces, leading to potential damage and explosion, and require large actuating elements that increase space requirements, particularly in vehicles.
Innovation Solution
A contact arrangement design with fixed contacts forming a loop to shield the contact bridge from magnetic fields, using a second leg as a spacer to attenuate repulsion forces, and incorporating ferromagnetic flow guiding pieces to counteract these forces, allowing for a compact and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high contact forces are generated to counteract repulsion forces during short-circuit, then reliability is improved, but device complexity and space requirements increase due to larger actuating elements
Solution Approach 1:
Ferromagnetic flow guiding pieces are introduced as intermediary components to redirect magnetic field lines and reduce repulsion forces on the contact bridge. These pieces act as mediators between the magnetic field source and the contact bridge, modifying the field distribution to achieve lower repulsive forces without requiring larger actuating elements.
Solution Approach 2:
The magnetic field distribution parameters are changed by introducing ferromagnetic flow guiding pieces with specific permeability and geometry. This alters the magnetic circuit parameters, concentrating field lines in desired paths and reducing the repulsive force parameter acting on the contact bridge during short-circuit conditions.
2Ease of manufacture
If the contact bridge is positioned outside the projection volume of fixed contacts, then ease of manufacture is improved, but magnetic field shielding effectiveness is reduced
Solution Approach 1:
Ferromagnetic flow guiding pieces serve as intermediaries that extend the magnetic shielding function to regions outside the fixed contact projection volume. These pieces create localized magnetic field concentration zones that guide field lines away from the contact bridge while maintaining compact positioning.
Solution Approach 2:
The solution moves from purely spatial positioning (inside/outside projection volume) to utilizing the third dimension of magnetic flux distribution. Ferromagnetic pieces shape the magnetic field in three-dimensional space, creating flux paths that protect the contact bridge even when positioned outside the traditional shielding zone.
3Reliability
If second leg of fixed contacts is used as spacer to attenuate repulsion forces, then reliability is improved, but device volume increases
Solution Approach 1:
The fixed contact structure uses composite geometry combining conductive material for current carrying and ferromagnetic material for field guidance. This composite approach allows the second leg to serve dual functions: electrical connection and magnetic field shaping, achieving repulsion force attenuation without excessive volume increase.
Solution Approach 2:
The second leg of the fixed contacts is designed to perform multiple functions simultaneously: providing electrical connection, maintaining mechanical spacing, and guiding magnetic field lines to reduce repulsion forces. This multi-functionality reduces the need for separate components and minimizes overall structure volume.
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 delays or suppresses the opening of the contact bridge even at high short-circuit currents up to 20 kA, ensuring safe and reliable operation without increasing the device's size.
Implementation Method 1
magnetic fields that arise due to current flow in the fixed contacts and that induce repulsive forces in the contact bridge
Implementation Method 2
incorporating ferromagnetic flow guiding pieces to counteract these forces
Implementation Method 3
switching contact elements of the contact bridge establish electrical contact with the respectively associated fixed contacts
Data Source
Figure 1
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Figure 4~5
AI summary
The present invention relates to a contact arrangement (100, 200, 300, 400) for an electrical switching device. The contact arrangement (100, 200, 300, 400) comprises two fixed contacts (102, 302, 402) and an electrically conductive contact bridge (104) which can be moved along a switching direction (118). The two fixed contacts (102, 302, 402) each have at least one first leg (122, 322, 422) and one second leg (124, 324, 424), wherein the two fixed contacts (102, 302, 402) are each connected to an outer surface (128, 328, 428) of the second leg (124, 324, 424), which is located on an outer side of a projection volume spanned by the first leg (122, 322, 422) and by the second leg (124, 324, 424) and can be electrically contacted by at least one switching contact element (112) of the contact bridge (104). Furthermore, the present disclosure relates to an electrical switching device with such a contact arrangement (100, 200, 300, 400).