Multi-Point Switch Contacts to Prevent Welding Under Short Circuits
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Solution Overview
Problem
Existing switching devices fail to handle high continuous and very high short-circuit currents without welding, often leading to destruction and replacement.
Innovation Solution
The switching device features at least two contact points with a movable contact and a fixed contact, where one contact is formed as a socket and the other as a pin, and includes ribbing in the form of contact lamellas or blades to distribute current and reduce resistance, using a resilient carrier strip and conductive contact pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional switching devices are used to conduct high continuous currents, then the device structure is simple, but the contacts weld together under very high short-circuit currents
Solution Approach 1:
The contact point is segmented into multiple contact points (e.g., three contact points instead of one). Each contact point has its own movable contact and fixed contact, distributing the current across multiple paths. This segmentation prevents welding by reducing the current density at each individual contact point while maintaining the overall high current carrying capacity.
Solution Approach 2:
The contact interface is transformed from a single-point contact to a multi-point contact arrangement distributed in space. The movable contact engages with multiple fixed contacts simultaneously, creating a distributed contact interface that increases the effective contact area and reduces stress concentration, thereby preventing welding under short-circuit conditions.
2Strength
If multiple contact points are created to distribute current, then the short-circuit resistance improves, but the device complexity increases
Solution Approach 1:
Multiple movable contacts are merged into a single common movable contact component that simultaneously engages with multiple fixed contacts. This merging approach creates multiple contact points without requiring multiple independent movable contact assemblies, thereby reducing overall device complexity while maintaining the current-distributing benefits of multiple contact points.
Solution Approach 2:
The common movable contact serves multiple functions: it provides electrical connection to all three phases, acts as the actuation point for opening/closing the switch, and distributes current across multiple contact points. This multi-functionality reduces the number of components needed and simplifies the overall device structure.
3Ease of manufacture
If high continuous currents are conducted through single contact points, then the device structure remains simple, but welding occurs under load
Solution Approach 1:
The single contact point is segmented into multiple contact points, distributing the harmful thermal and electrical stress across multiple locations. This prevents the concentration of energy that leads to welding, while the modular design of the contact points maintains manufacturing simplicity through standardized components.
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 device can safely conduct high continuous currents up to 1000A and short-circuit currents up to 30kA without welding, requiring low actuation forces and maintaining stability.
Implementation Method 1
a high-current contact strip (27), which comprises a resilient carrier strip (30) with two edge webs (28) and a plurality of contact webs (29) extending transversely to the edge webs and connected to the edge webs, wherein contact pieces (31) are riveted onto the contact webs (29)
Implementation Method 2
The contact blades are preferably designed as an annular band or sleeve, i.e. as a high-current contact band, which can be easily pushed onto the pin or inserted into the socket. This enables a simple design, as the spring force is geometrically contained in the annularly arranged contact blades.
Data Source
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AI summary
The present invention relates to a switching device (1) for conducting high continuous currents and very high short-circuit currents. The present invention addresses the problem of providing a switching device which avoids the problems known from the prior art and which, in particular when in the unseparated state, i.e. the contacted state, can conduct high continuous currents and even higher short-circuit currents without welding. This problem is solved according to the invention in that the switching device (1) comprises at least two contact locations (9, 10), wherein: each contact location comprises a movable contact (11) and a fixed contact (12), one of the contacts (12) of each contact location (9, 10) being formed in a socket (13) and the other contact (11) of each contact location (9, 10) being formed on a pin (14) which can be received in the socket (13), and the movable contacts (11) of both contact locations (9, 10) being in the form of a common component; one of the contacts (12) at at least one of the contact locations (9, 10) has ribs (26), so that at the contact location (9, 10) a plurality of contact points is defined, the ribs being a separate component in the form of contact lamellae, said component being arranged on the corresponding contact of each contact location, and the contact lamellae being in the form of a high-current contact strip (27), which comprises a resilient carrier strip (30) having two boundary flanges (28) and comprises a plurality of contact flanges (29), which run perpendicularly to the boundary flanges (28) and are connected to the boundary flanges (28); contact pieces (31) are riveted onto the contact flanges (29).