Knife Switch Nozzle Layout for Proximal Arc Cooling
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Solution Overview
Problem
Existing electric switches for medium- and high-voltage switchgear face challenges in effectively suppressing arcs during current interruption and contact making events, with existing arc-extinction methods being suboptimal.
Innovation Solution
An electric current switch design featuring a contact lever with a fixed nozzle surrounding the fixed arcing contact, which directs cooling gas proximally to suppress arcs, utilizing a puffer mechanism to provide compressed cooling gas through hoses or pipes to the nozzle, and incorporating inclined surfaces to guide hot gas away from the fixed main contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nozzle is fixed to the fixed contact assembly to direct cooling gas proximally, then arc suppression effectiveness is improved, but device complexity increases
Solution Approach 1:
The nozzle is fixedly attached to the fixed contact assembly, merging the arc suppression function with the existing structural component. This integration reduces the number of separate parts while maintaining the effectiveness of proximal-directed cooling gas flow for arc suppression.
2Reliability
If cooling gas is directed in the proximal direction towards the arc root, then arc extinction effectiveness is improved, but hot gas flow towards main contacts increases
Solution Approach 1:
The nozzle is designed with specific outlet orientations that direct cooling gas locally towards the arc root in the proximal direction. The inclined surfaces at the nozzle outlets create localized gas flow patterns that suppress arcs at their origin while minimizing hot gas migration towards the main contacts through geometric control of the flow direction.
3Device complexity
If the contact lever moves for switching while the nozzle remains static, then the number of moving parts is reduced, but the precision of cooling gas delivery to the arc may be compromised
Solution Approach 1:
The nozzle is pre-positioned and fixedly attached to the fixed contact assembly in an optimal location that anticipates the arc formation position. The inclined surfaces are pre-configured to guide cooling gas effectively towards the expected arc root position, ensuring precise delivery without requiring the nozzle to move during operation.
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 achieves improved arc suppression by minimizing hot gas flow towards the fixed main contacts, reducing the complexity of moving parts, and enhancing the effectiveness of arc extinction using various cooling gases, resulting in a more compact and efficient switch.
Implementation Method 1
the nozzle comprising at least one outlet to provide a flow of cooling gas towards the fixed arcing contact, the flow of cooling gas being in the proximal direction of the contact lever
Implementation Method 2
provide a flow of cooling gas towards the fixed arcing contact... provides for reduced amounts of hot gas flowing towards the fixed main contacts
Data Source
AI summary
An electric current switch comprising: a housing; a contact lever including a proximal end and a distal end and is rotatable at a pivot point at the distal end, the contact lever including a lever arcing contact area and a lever arcing contact at the proximal end; a fixed contact assembly configured to receive the contact lever in a closed position of the contact lever, the fixed contact assembly including fixed main contacts and a fixed arcing contact, the fixed contact assembly being fixed relative the housing accommodating the fixed contact; the contact lever is configured to rotate about the pivot point between the closed position and an open position, the electric current switch further including a nozzle fixedly arranged to surround the position of the fixed arcing contact, the nozzle including at least one outlet to provide a flow of cooling gas towards the fixed arcing contact, the flow of cooling gas being in the proximal direction of the contact lever as when the contact lever in the closed position.