Angled Electrical Contactor Contact Bars Reduce Blow-Apart Force
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Solution Overview
Problem
Low current electrical contactors face issues with high blow-apart forces during fault events, leading to potential welding of contact discs due to manufacturing tolerances and uneven current distribution, which existing designs struggle to mitigate effectively.
Innovation Solution
The design incorporates an angled configuration for the contact bars, providing multiple parallel current paths and angled contact discs to ensure simultaneous contact, reducing blow-apart forces and requiring less closing force from the actuating device and spring, while allowing for flexibility in the moving contact bar to accommodate manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact discs are positioned directly opposed to each other on stationary and moving contact bars, then current flow is established, but manufacturing tolerances cause uneven contact timing and concentrated current paths leading to high blow-apart forces
Solution Approach 1:
The current path is segmented into multiple parallel paths by positioning contact discs at angles to each other. Instead of a single direct contact path, the current divides into several paths through the angled contact disc arrangement, reducing the concentration of current and thereby reducing the blow-apart force at any single contact point.
Solution Approach 2:
The contact discs are positioned at angles relative to each other rather than in direct opposition, creating an asymmetric arrangement. This angular positioning ensures that contact occurs at multiple points simultaneously and distributes the current flow across angled surfaces, reducing concentrated stress and blow-apart forces while accommodating manufacturing tolerances.
2Manufacturing precision
If contact discs are positioned to allow flexibility for manufacturing tolerances, then contact timing improves, but current distribution becomes uneven leading to welding risks during fault events
Solution Approach 1:
The current path is divided into multiple parallel paths through the angled contact disc arrangement. This segmentation ensures that even with manufacturing tolerances, the current is distributed across multiple paths rather than concentrated at single contact points, reducing the risk of welding during fault events.
Solution Approach 2:
The contact discs are positioned at angles to each other, introducing a dimensional aspect to the contact arrangement. This angular positioning creates multiple contact points and current paths in different orientations, ensuring better current distribution and reducing welding risks while accommodating manufacturing variations.
3Reliability
If closing force is increased to prevent welding during fault events, then contact reliability improves, but actuating device complexity and required force increase
Solution Approach 1:
By segmenting the current path into multiple parallel paths through angled contact disc positioning, the blow-apart force is reduced. This allows the closing force to be lower while still maintaining sufficient contact pressure to prevent welding during fault events, as the force is distributed across multiple contact points rather than concentrated at a single point.
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 angled configuration effectively reduces the blow-apart force per path by a factor of four, minimizing the risk of contact disc welding during fault events and ensuring reliable operation in high current applications by distributing current evenly across multiple paths.
Implementation Method 1
This constriction generates a magnetic force proportional to the square of the current, which acts to drive the contact disc pairs 104A/105A and 104B/105B apart.
Data Source
AI summary
An electrical contactor includes a first stationary contact bar with first and second contact surfaces, and a single moving contact bar with first and second contact surfaces. The first and second contact surfaces of the first stationary contact bar and the first contact surface of the single moving contact bar are configured such that, when the single moving contact bar travels towards the first stationary contact bar, the first contact surface of the single moving contact bar touches the first contact surface of the first stationary contact bar in a first contact point, and the second contact surface of the first stationary contact bar in a second contact point. At least one of the first and second contact surfaces of the first stationary contact bar or the first contact surface of the single moving contact bar have a convex shape to establish the first and second contact points.