Electric Arc-Blast Nozzle Composite Insert for CO2 Circuit Breakers
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Solution Overview
Problem
Conventional electric arc-blast nozzles using sulfur hexafluoride (SF6) as the cut-off gas face challenges with greenhouse gas emissions, and alternatives like carbon dioxide (CO2) struggle with insufficient blasting pressure for effective electric arc cut-off, especially during long arcing times, leading to increased costs and material erosion.
Innovation Solution
An electric arc-blast nozzle with a composite insert made from a fluorocarbon polymer matrix and inorganic fillers, such as SiO2 and graphite, is designed to enhance thermal resistance and maintain the axial passage section, allowing for effective arc cut-off with CO2 or CO2-based gas mixes without significant size or cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CO2 is used as cut-off gas instead of SF6, then environmental impact is reduced (lower GWP), but blasting pressure decreases too quickly during long arcing times
Solution Approach 1:
The nozzle is constructed with a composite material consisting of a fluorocarbon polymer matrix (such as PTFE) reinforced with inorganic fillers (such as Al2O3, SiO2, or other metal oxides). This composite structure enhances the nozzle's thermal resistance and mechanical strength, allowing it to withstand the thermal and pressure conditions during arc cut-off with CO2 gas, thereby maintaining effective blasting pressure throughout the arcing process.
2Stress or pressure
If the axial passage section is reduced to increase blasting pressure, then arc cut-off effectiveness improves, but material erosion increases
Solution Approach 1:
The composite material with inorganic fillers provides enhanced erosion resistance while maintaining the reduced axial passage section design. The inorganic particles (Al2O3, SiO2, etc.) embedded in the fluorocarbon polymer matrix protect the nozzle walls from arc-induced erosion, allowing the passage to remain small enough to generate high blasting pressure without suffering from excessive material loss during operation.
Solution Approach 2:
The invention optimizes the parameters of the axial passage (diameter, length, shape) to achieve the right balance between generating sufficient blasting pressure and minimizing material erosion. By carefully controlling the passage dimensions and the composite material properties, the design maintains effective arc cut-off performance while reducing erosive effects on the nozzle material.
3Stress or pressure
If a larger swabbing volume is used to increase blasting pressure with CO2, then arc cut-off effectiveness improves, but device dimensions and cost increase
Solution Approach 1:
The invention optimizes the swabbing volume parameters to achieve adequate blasting pressure with CO2 without excessive enlargement of the circuit breaker. By adjusting the piston section area, gas reservoir volume, and compression ratio, the design achieves effective arc cut-off with a compact overall size, avoiding the need for significantly larger dimensions compared to SF6-based systems.
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 nozzle achieves improved electrical endurance and maintains arc cut-off performance with CO2, reducing material erosion and ensuring consistent pressure, thus overcoming the limitations of conventional nozzles with SF6 and CO2.
Implementation Method 1
the insert is formed by another dielectric material, separate from the first material and chosen from among: a composite material obtained from a second composition comprising a fluorocarbon polymer matrix and: at least one inorganic filler A chosen from among a sulfur, a ceramic and an oxide chosen from among SiO2, TiO2, Al2O3
Implementation Method 2
an electric arc cut-off gas circulating in the axial passage of the median part to cut an electric arc... the function of such a nozzle is to channel the electric arc and, in doing so, increase the pressure of the cut-off gas around the electric arc
Implementation Method 3
the blasting pressure of the electric arc must necessarily be higher when using CO2, instead of SF6, as the cut-off gas... the section of the axial passage for cutting the electric arc of the median part of the nozzle is reduced to encourage the increase in pressure of the cut-off gas
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a nozzle (20) with an electric arc-blast comprising of a median part (27) made of a first dielectric material and two end parts (9, 11). The nozzle (20) comprises an insert (22) made of a second dielectric material, separate from the first dielectric material and chosen from among: a composite material obtained from a second composition comprising a fluorocarbon polymer matrix and at least one inorganic filler A chosen from among a sulfur, a ceramic and an oxide chosen from among SiO2, TiO2, Al2CoO4, ZnO, BaTiO3 and P2O5, in a percentage weight ranging between 0.1 % and 10 %, with respect to the total weight of the second composition, and/or at least one inorganic filler B chosen from among a graphite, a mica, a glass and a fluoride, in a percentage weight ranging between 5 % and 50 %, with respect to the total weight of the second composition, and a ceramic material obtained from a third composition comprising at least one compound chosen from among a carbide, a boride and an oxide. The invention also relates to a circuit breaker comprising such a nozzle (20).