Switching Device Spreader Member Contact Area Control
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Solution Overview
Problem
Existing blade contact switching devices experience a gradual increase in mutual contact area during closure, leading to potential short circuits that can damage contacts before the maximum contact area is reached, compromising short circuit performance.
Innovation Solution
Incorporating a spreader member that moves the movable contact laterally away from the fixed contact, ensuring contact only after the movable contact has pivoted to overlap partially with the fixed contact, thereby increasing the contact area more rapidly and enhancing short circuit withstand capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable contact pivots towards the fixed contact during closing operation, then the mutual contact area increases gradually, but the short circuit current can destroy the contacts before maximum contact area is reached
Solution Approach 1:
The spreader member is designed to preliminarily position the movable contact in a spread state before the closing operation begins. During the closing operation, the movable contact starts from this pre-positioned state, allowing the contact area to increase more rapidly from the outset, rather than gradually building up from zero. This preliminary positioning enables the contact area to reach its maximum value faster, improving short circuit performance.
Solution Approach 2:
The invention introduces a lateral dimension (parallel to the pivoting axis) for contact area development. By spreading the movable contact laterally and maintaining this lateral separation during closing, the contact area increases not only through the traditional pivoting motion but also through the lateral dimension, enabling faster overall contact area increase and better short circuit withstand capability.
2Speed
If the spreader member moves the movable contact laterally away from the fixed contact, then the contact area increases faster, but the device complexity increases
Solution Approach 1:
The spreader member is integrated as part of the movable contact assembly, combining the spreading function with the existing movable contact structure. This integration approach allows the lateral spreading motion to be achieved using the same actuation mechanism that drives the closing operation, rather than requiring a separate independent actuation system, thereby limiting the increase in device complexity.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A switching device (2) comprising a frame (201), a first fixed contact member (34) having a first contact area (341), and a first movable contact member (4) having a first contact arm (41) provided with a contact area. The first movable contact member (4) is adapted to pivot relative to the frame (201) around a first pivoting axis (45) between a first position and a second position. The switching device (2) comprises a spreader member (6) that is adapted to provide a first intermediate position for the first movable contact member (4) in which a projection of the contact area of the first contact arm (41) overlaps at least partially with a projection of the first contact area (341) on a switch plane perpendicular to the first pivoting axis (45) while the contact area of the first contact arm (41) is spaced apart from the first contact area (341).