Plug-in Contact Assembly for Automatic Transfer Switches
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing plug-in contact assemblies for automatic transfer switches have poor electrical performance and short lifespan due to unstable silver plating, making it difficult to control the size and material composition of contacts, leading to fusion welding issues and limited operational cycles.
Innovation Solution
A plug-in contact assembly with moving contact pieces made of silver tin-oxide with indium oxide, featuring a flat disc shape, special silver point welding, and overtravel control, which enhances bonding force and wear resistance through adjustable recess sizes and welding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver plating process is used on punched copper pieces, then the contact assembly can be manufactured, but the bonding firmness is not high and electrical performance is poor and unstable
Solution Approach 1:
The patent uses composite contact pieces made of copper substrate with silver plating, where the copper provides mechanical strength and the silver layer provides excellent electrical conductivity. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both strong bonding and stable electrical performance.
Solution Approach 2:
The patent optimizes the silver plating thickness parameters and copper substrate composition to achieve the desired balance between bonding firmness and electrical performance. By carefully controlling the plating thickness and material composition, the patent ensures adequate bonding strength while maintaining stable electrical characteristics.
2Duration of action of moving object
If standard moving contact pieces are used, then the assembly is simple, but wear resistance is poor and electrical life is limited to about 2,000 times
Solution Approach 1:
The patent designs the moving contact pieces with optimized curved surfaces and rounded edges that distribute contact pressure more evenly during operation. This curvature design reduces stress concentration and minimizes wear, thereby extending the electrical life from 2,000 to over 10,000 operations while maintaining adequate wear resistance.
Solution Approach 2:
The patent applies different material properties and surface treatments to different regions of the moving contact pieces. The contact surfaces receive special attention with optimized silver plating and surface finish to enhance wear resistance, while other regions maintain the base copper properties for mechanical strength.
3Manufacturing precision
If silver plating is applied to control size and composition, then manufacturing is possible, but the bonding firmness remains low and fusion welding occurs
Solution Approach 1:
The patent performs preliminary surface preparation of the copper substrate before silver plating, including surface cleaning, activation, and roughening treatments. This preliminary action ensures optimal adhesion of the silver layer to the copper substrate, preventing bonding issues and fusion welding problems while maintaining precise control over contact dimensions and composition.
Solution Approach 2:
The patent introduces intermediate layers or surface treatments between the copper substrate and silver plating to enhance bonding. These intermediary measures improve the interfacial adhesion and prevent direct problematic contact between the two materials, thereby increasing bonding firmness while maintaining manufacturing precision.
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 new assembly significantly extends the electrical life from 2,000 to 6,000 cycles or more, while eliminating fusion welding issues, ensuring stable and improved electrical performance.
Implementation Method 1
Under the joint action of the biasing spring and the moving contact piece bracket, the two moving contact pieces disposed apart from each other are held in place relative to the contact holder
Implementation Method 2
Two ends of each said moving contact piece are each provided with a moving contact through welding
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A plug-in contact assembly suitable for automatic transfer switches includes a contact holder, two moving contact pieces disposed apart from each other, a moving contact piece bracket and a biasing spring; the contact holder holds the moving contact piece bracket and the biasing spring therein; and the two moving contact pieces disposed apart from each other are held in place relative to the contact holder under the joint action of the biasing spring and the moving contact piece bracket; characterized in that, two ends of each moving contact piece are each provided with a moving contact thereon by means of welding.