Switching Device Rack Gear Arc Separation
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Solution Overview
Problem
Existing switching devices face challenges in breaking high currents efficiently, as they require stretching the arc over a long distance to increase arc voltage and cool it effectively, while avoiding contact erosion and ensuring rapid current decay to zero.
Innovation Solution
The use of a rack and gear mechanism to create a longer separation distance and higher separation speed between arcing contacts, allowing for a longer arc length and faster increase in arc voltage, while the actuating unit handles the main contacts over a shorter distance, with a gear ratio of 2:1 to 8:1 and harder arcing contact tips for improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contacts are separated to a long distance to stretch the arc, then the arc voltage increases and current breaking is improved, but the device complexity and size increase
Solution Approach 1:
The patent divides the contact system into two separate functional assemblies: a main contact assembly for current conduction and an arcing contact assembly for arc management. This segmentation allows each assembly to be optimized independently - the main contacts remain close together for low resistance connection, while the arcing contacts are separated by long distance to stretch and extinguish the arc effectively
Solution Approach 2:
The patent introduces an arcing contact assembly as an intermediary between the main contacts and the arc. The arcing contacts serve as a mediator that handles the arc extinction function, allowing the main contacts to focus on current conduction without being damaged by arc erosion
2Productivity
If the contacts are separated quickly to break current rapidly, then the current decay speed is improved, but the contact erosion increases
Solution Approach 1:
The patent extracts the arc extinction function from the main contact assembly and places it in a separate arcing contact assembly. The arcing contacts are specifically designed to handle the arc, taking the harmful erosion away from the main current-carrying contacts. This allows rapid contact separation for fast current breaking without compromising the main contacts through repeated arc exposure
Solution Approach 2:
The arcing contacts are designed as sacrificial elements that can be replaced more easily than the main contacts. They serve as a disposable or easily replaceable component that absorbs the damage from rapid separation and arc extinction, protecting the more critical main contact assembly
3Reliability
If the arcing contacts are separated over a long distance, then the arc length increases and arc voltage rises, but the actuating mechanism becomes more complex
Solution Approach 1:
The patent employs a rack and pinion gear mechanism that converts rotational motion into linear motion, enabling the arcing contacts to traverse a long linear distance for arc stretching. The gear ratio (2:1 to 8:1) allows a compact rotational actuator to produce the equivalent of a much longer linear actuation path, achieving long arc length without a proportionally complex actuating mechanism
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 solution enables faster and more efficient current decay to zero, prolonging the switching device's lifespan and allowing for a more compact design, while the actuating unit is easier to build for the shorter main contact distance.
Implementation Method 1
When breaking a current without any natural zero-crossings, it is necessary to force the current down to zero. One common practice is to create a voltage across the breaking point that is higher than the system voltage thus forcing the current to decrease to zero. In order to achieve such a voltage across the breaking point it is desired to stretch the breaking arc over a long distance since the length of the arc increases the arc voltage
Implementation Method 2
a first rack and a first gear are provided for actuating the arcing contact carrier so that, when interrupting the current, a separation distance between the arcing contacts is longer than a separation distance between the main contacts
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~3d
AI summary
The present disclosure relates to switching device (1, 100, 200) for breaking an electric current comprising a main contact carrier (65, 165, 265), a movable main contact (30, 130, 230) and a stationary main contact (20, 120, 220), wherein the movable main contact (30, 130, 230) is attached to the main contact carrier (65, 165, 265), an arcing contact carrier (60, 160, 260), a movable arcing contact (50, 150, 250) and a stationary arcing contact (40, 140, 240), wherein the movable arcing contact (50, 150, 250) is attached to the arcing contact carrier (60, 160, 260) and the stationary arcing contact (40, 140, 240) is arranged in parallel with the stationary main contact (20, 120, 220), and an actuating unit (10, 110, 210) for actuating the main and arcing contact carriers (65, 165, 265; 60, 160, 260) from an open position to close position or vice versa at a actuating distance, wherein there are separation distances between the stationary and movable contacts of the main and arcing contact units respectively when the current is interrupted. The switching device further includes a first rack (90, 190, 290) and a first gear (80, 180, 280) for actuating the arcing contact carrier (60, 160, 260) so that, when interrupting the current, a separation distance between the arcing contacts (50, 150, 250; 40, 140, 240) is longer than a separation distance between the main contacts (30, 130, 230; 20, 120, 220).