Contactor Serrations for Heat Dissipation and Arcing Prevention
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Solution Overview
Problem
Contactors face issues with heat transport efficiency due to non-perfect parallelism of contact surfaces, leading to hotspots and increased resistance, as well as arcing and welding risks during current peaks, which can cause mechanical separation and operational failures.
Innovation Solution
The contact surfaces are designed with serrations that intersect to create multiple contact points, allowing efficient heat dissipation and reducing the risk of arcing by distributing the contact area without requiring perfect parallelism, with serration angles between 50°-120° and depths of 0.2-2 mm, and configurations such as parallel or concentric serrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If contact sides are made parallel to each other, then contact area is increased, but manufacturing precision cannot be achieved due to impossibility of perfect parallelism in series production
Solution Approach 1:
The contact sides are segmented into multiple serrations that extend in parallel. Each serration creates individual contact spots when intersected by the other contact side's serrations, transforming a single large contact area requirement into multiple smaller contact spots that are easier to manufacture with consistent parallelism.
Solution Approach 2:
Instead of requiring the entire contact side to be perfectly parallel, the invention applies parallelism locally to each serration. The serrations are designed with specific geometric parameters (depth 0.2-2mm, angle 50°-120°) that ensure proper contact spot formation even with slight variations in overall parallelism.
2Force
If contact area is concentrated in one location, then contact force is increased, but heat transport efficiency decreases due to hotspot formation
Solution Approach 1:
The contact interface is segmented into multiple distributed contact spots formed by the intersection of serrations. This segmentation distributes the total contact force across multiple locations, preventing concentration of heat in a single hotspot while maintaining sufficient contact pressure at each spot for low contact resistance.
Solution Approach 2:
The serrations extend in parallel across the contact side, adding a dimensional distribution pattern to the contact interface. This creates a systematic arrangement of contact spots that distributes heat generation across the contact area, improving thermal management while maintaining mechanical contact force.
3Reliability
If contact members are pressed together with high force, then contact resistance is reduced, but lifting force during current peaks increases causing arcing and welding
Solution Approach 1:
The contact force is segmented and distributed across multiple serration intersections rather than being concentrated at a single point. This distribution reduces the lifting force at each individual contact spot during current peaks, minimizing the risk of arcing and welding while maintaining low overall contact resistance through the distributed contact network.
4Reliability
If serrations are made with larger depth and angle, then contact spot distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The invention defines specific parameter ranges for serration geometry (depth 0.2-2mm, angle 50°-120°) that optimize contact spot distribution while remaining manufacturable. These parameter ranges balance the need for adequate contact spot separation and distribution against the complexity of manufacturing the serrations, providing a practical solution for series production.
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
This design enhances heat transport efficiency, reduces temperature hotspots, and minimizes arcing and welding risks, ensuring reliable operation even under high currents, by maintaining a distributed contact area and reducing the lifting force during current peaks.
Implementation Method 1
The efficiency of heat transport away from one single larger contact spot will be lower than if the contact interface would be more distributed
Implementation Method 2
which results in a totally higher temperature of the contact members in the contact surface, and this is getting hotter in the middle than at the outer borders thereof
Data Source
Figure 1~4
Figure 5~7
AI summary
A contactor has two contact elements (1, 2) each having a contact member (3, 4) adapted to bear with the contact side (5, 6) thereof against a said contact side of the other contact member for enabling an electric current to flow between said to contact elements. The contact sides of both contact members are provided with serrations (11, 12) extending so that elongated ridge-like peaks (13) of serrations of one said contact side intersect such peaks of the other said contact side while forming a plurality of spots of mutual contact of these contact sides distributed over the area of said contact sides.