Contact Bridge Layout to Resist Short-Circuit Repulsion
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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, necessitating large actuating elements that increase space requirements, particularly in vehicles.
Innovation Solution
A contact arrangement design with fixed contacts forming a loop around a movable contact bridge, utilizing a second leg as a spacer to attenuate repulsive forces, and incorporating ferromagnetic flow guiding pieces to counteract these forces, allowing for a compact and reliable operation even at high short-circuit currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high contact forces are generated to counteract repulsion forces during short-circuit, then the switching device can withstand short-circuit currents, but the space required increases due to larger actuating elements
Solution Approach 1:
The patent positions the contact bridge outside the projection volume of the fixed contacts, utilizing spatial arrangement in three-dimensional space to reduce interference and repulsion forces, thereby maintaining reliability without increasing overall device volume
Solution Approach 2:
Ferromagnetic flow guiding pieces are introduced as intermediary elements to redirect magnetic flux and reduce repulsion forces between contacts, enabling the device to withstand short-circuit currents without requiring larger actuating elements
2Ease of manufacture
If the contact bridge is positioned inside the projection volume of fixed contacts, then assembly is simplified, but repulsion forces during short-circuit increase causing uncontrolled opening
Solution Approach 1:
The contact bridge is positioned outside the projection volume of the fixed contacts along the arrangement direction, utilizing spatial separation to reduce repulsion forces while maintaining assembly simplicity through the standardized actuation device
Solution Approach 2:
The asymmetric positioning of the contact bridge relative to the fixed contacts creates favorable magnetic field distribution and reduces repulsion forces, while the second leg of fixed contacts provides symmetric support structure
3Device complexity
If conventional contact arrangements are used, then the device structure is simple, but uncontrolled opening occurs during short-circuit leading to damage or explosion
Solution Approach 1:
Ferromagnetic flow guiding pieces serve as intermediaries to control and redirect magnetic flux, preventing uncontrolled opening during short-circuit while maintaining relatively simple device structure
Solution Approach 2:
The fixed contacts are divided into multiple legs (first leg and second leg), with the second leg serving as a spacer to reduce repulsion forces, enabling reliable operation without significantly increasing structural complexity
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 at short-circuit currents up to 20 kA, ensuring safe and reliable operation without increasing the device's size, while simplifying assembly and arc impact management.
Implementation Method 1
incorporating ferromagnetic flow guiding pieces to counteract these forces
Implementation Method 2
strong repulsion forces (also referred to in the following as 'repulsive forces') that arise in the event of a short-circuit at such currents
Implementation Method 3
the second leg of the fixed contacts serves respectively as a spacer between the respective first leg and the contact bridge, so that repulsive forces (or repulsion forces) induced on the contact bridge by the current flow in the first leg are attenuated by the distance
Implementation Method 4
the switching contact elements of the contact bridge establish electrical contact with the respectively associated fixed contacts
Implementation Method 5
an electrical switching device with such a contact arrangement... an actuation device, which is designed to move the contact bridge of the contact arrangement between the closed position and the open position
Data Source
AI summary
A contact arrangement for an electrical switching device and an electrical switching device with such a contact arrangement. The contact arrangement comprises two fixed contacts and an electrically conductive contact bridge which can be moved along a switching direction. The two fixed contacts each have at least one first leg and one second leg, wherein the two fixed contacts are each connected to an outer surface of the second leg, which is located on an outer side of a projection volume spanned by the first leg and by the second leg and can be electrically contacted by at least one switching contact element of the contact bridge.