Knife Switch De-Latching Mechanism for Puffer Arc Extinction
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Solution Overview
Problem
Existing electric current switches for medium- and high-voltage switchgear face challenges in effectively suppressing arcs during current interruption and contact making events, particularly when the moving electric connecting part needs to reach a third position beyond the open position while maintaining efficient arc-extinction.
Innovation Solution
The electric current switch incorporates a de-latching mechanism that decouples the motion of the puffer piston from the contact lever once the contact lever reaches the open position, allowing it to rotate freely to an earthed position. This design enables the puffer piston to achieve maximum gas pressure at the moment of current interruption, ensuring effective arc-extinction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the puffer piston is mechanically coupled to the contact lever throughout the entire motion range, then the gas pressure can be built up for arc-extinction, but the contact lever cannot reach the earthed position beyond the open position
Solution Approach 1:
The mechanical coupling between the puffer piston and contact lever is segmented into two distinct phases: a coupled phase during current interruption (open position) and a decoupled phase during earthed position movement. The de-latching mechanism enables this segmentation by allowing the piston to remain coupled only when needed for arc-extinction, while permitting the contact lever to move independently to the earthed position without the piston's constraint.
Solution Approach 2:
The coupling state between the puffer piston and contact lever changes dynamically during operation. The system transitions from a coupled state (when the contact lever moves to the open position for current interruption) to a decoupled state (when the contact lever moves to the earthed position). This dynamic adjustment allows the system to optimize both arc-extinction performance and operational range.
2Ease of operation
If the contact lever is allowed to rotate freely to the earthed position, then the third position beyond open position is achieved, but the puffer piston cannot achieve maximum gas pressure at the moment of current interruption
Solution Approach 1:
The de-latching mechanism is designed to maintain the coupled state between the piston and contact lever during the approach to the open position, ensuring that the piston compresses the gas to maximum pressure before the current interruption occurs. The de-latching action is triggered at the appropriate moment (when the contact lever reaches the open position), allowing the preliminary gas compression to be completed before decoupling occurs.
3Device complexity
If the puffer piston moves with the contact lever throughout the entire range, then the mechanism is simple, but the puffer volume cannot be optimized for maximum gas pressure
Solution Approach 1:
The de-latching mechanism acts as an intermediary element between the puffer piston and contact lever. This intermediary component enables the system to achieve both simple overall structure and optimized gas pressure by mediating the relationship between the piston and contact lever - maintaining coupling when needed for pressure buildup, and allowing decoupling when needed for operational range.
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 de-latching mechanism allows the contact lever to reach the earthed position without interfering with the puffer piston's motion, achieving efficient arc-extinction and enabling the puffer to maintain maximum gas pressure during current interruption, thus addressing the limitations of prior art.
Implementation Method 1
a compressed gas device having a movable piston in a volume housing gas compressible by the piston, the compressed gas being ejected from a nozzle towards the fixed contact assembly
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The present invention relates to an electric current switch comprising a compressed gas device (126) having a movable piston (128) in a volume (130) housing gas compressible by the piston, the compressed gas being ejected from a nozzle (108) towards a fixed contact assembly, the piston is mechanically coupled to the contact lever via a de-latching mechanism (132; 301; 402; 502) configured to decouple the motion of the piston from the contact lever when the contact lever moves from the open position towards the earth position.