Automatic Transfer Switch Contact Structure for Arc Extinguishing
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Solution Overview
Problem
Existing automatic transfer switches suffer from unstable contact bouncing during closing and opening, leading to electric arc formation that ablates contacts and reduces switch life, and ineffective arc extinguishing within the electric arc extinguishing chamber.
Innovation Solution
The automatic transfer switch design includes a stationary contact with a hook-shaped structure and opposing current flow directions to generate Lorentz forces that guide arcs into an extinguishing chamber, along with a shield piece to weaken interfering magnetic fields, and a movable contact with a two-piece arc contact point and multiple contact points for stability and redundancy, using high melting point alloys to minimize ablation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the movable contact is designed to pivot between closing and opening positions, then the switch can perform power transfer function, but contact bouncing occurs during operation leading to electric arc formation and contact ablation
Solution Approach 1:
The stationary contact is divided into two separate parts: a stationary arc contact point and a stationary main contact point. This segmentation allows the arc contact point to handle electric arc extinction while the main contact point handles current conduction, separating the harmful arc effects from the primary contact function and reducing contact ablation.
Solution Approach 2:
An electric arc extinguishing chamber with grid pieces is introduced as an intermediary component between the movable contact and the stationary contact. This chamber captures and extinguishes electric arcs generated during contact operation, preventing direct arc contact between the movable and stationary contacts, thereby reducing contact ablation and improving reliability.
2Object-generated harmful factors
If the electric arc extinguishing chamber is provided with grid pieces, then electric arc can be divided and extinguished, but the existing design cannot effectively introduce the electric arc into the chamber
Solution Approach 1:
The stationary arc contact point is positioned and oriented in advance to directly face the movable contact's arc generation zone. The stationary contact's second part is extended to be flush with the upper edge of the grid pieces, pre-positioning the arc capture path before the switching operation occurs, ensuring arcs are effectively channeled into the extinguishing chamber.
Solution Approach 2:
The stationary contact is designed with a three-dimensional hook-shaped structure where the first part and second part are connected at an angle. The second part extends in a direction perpendicular to the current flow, creating a spatial pathway that guides arcs from the horizontal contact plane into the vertical electric arc extinguishing chamber, effectively introducing arcs into the chamber.
3Ease of manufacture
If the stationary contact structure is simplified, then manufacturing is easier, but the contact between movable contact and stationary contact becomes unstable
Solution Approach 1:
The stationary contact is designed with a flexible hook-shaped structure that can elastically deform under electromagnetic forces. The angled connection between the first and second parts allows the contact to dynamically adjust its position during switching operations, maintaining stable contact pressure and arc guidance without requiring complex rigid support structures.
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 enhances contact stability, reduces arc formation, and prolongs the electrical life of the switch by effectively extinguishing arcs, improving performance and reliability.
Implementation Method 1
a flow direction of current in the second part of the stationary contact is approximately opposite to a flow direction of current in the movable contact, so as to provide a Lorentz force to an electric arc generated during disconnecting towards the electric arc extinguishing chamber
Data Source
Figure 1
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AI summary
An automatic transfer switch, including: a stationary contact, including a stationary arc contact point and a stationary main contact point, and configured to receive current from a power supply; a movable contact, including a movable arc contact point and a movable main contact point, being pivotally connected to a load and capable of pivoting between a closing position contacting with the stationary contact and a opening position not contacting with the stationary contact; an electric arc extinguishing chamber, including a plurality of grid pieces, and configured to eliminate an electric arc generated when the movable contact and the stationary contact are switched off, the stationary contact includes a first part and a second part which are connected at an angle, the first part is configured to receive current from a power supply, the second part is configured to be in contact with the movable contact, and an end of the second part extends to be flush with an upper edge of the grid pieces of the electric arc extinguishing chamber, and a flow direction of current in the second part of the stationary contact is approximately opposite to a flow direction of current in the movable contact, so as to provide a Lorentz force to an electric arc generated during disconnecting towards the electric arc extinguishing chamber.