Converging Main Nozzle for High-Voltage Switching Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas-insulated high-voltage switching devices, such as circuit breakers, exhibit low dielectric withstand during low short-circuit current duties due to insufficient gas flow conditions, leading to potential dielectric breakdown and failure.
Innovation Solution
The design incorporates a main nozzle throat with a frusto-conical shape and a substantially converging duct, which increases the gas density and flow velocity, effectively removing hot gas from the arcing zone, thereby enhancing dielectric withstand by accelerating the arc-extinguishing gas to higher velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main nozzle throat has a conventional design (zero length or diverging duct), then the device complexity is reduced and manufacturing is easier, but the dielectric withstand is insufficient during low short-circuit current duties
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the main nozzle throat - specifically implementing a frusto-conical shape with a length L between 15-80 mm and an aperture angle α between 0°-15°. This changes the flow characteristics from subsonic to supersonic, achieving effective dielectric withstand during low short-circuit current duties while maintaining manufacturing feasibility through standardized dimensional ranges.
Solution Approach 2:
The patent employs curvature principles by using a frusto-conical shape with smooth transitions and rounded edges throughout the nozzle structure. The aperture angle α creates a controlled conical curvature that optimizes gas flow acceleration, while the overall frusto-conical geometry provides smooth flow paths that reduce turbulence and enhance dielectric recovery.
2Reliability
If the main nozzle throat is designed with a frusto-conical shape and converging duct, then the gas flow velocity and dielectric withstand are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges - length L between 15-80 mm and aperture angle α between 0°-15° - that balance manufacturing capability with performance requirements. These standardized ranges allow conventional manufacturing processes to achieve the required precision without excessive complexity, while still delivering supersonic flow conditions and improved dielectric withstand.
Solution Approach 2:
The frusto-conical shape concentrates the most critical geometric precision requirements in the throat region where the aperture angle α and length L directly control flow acceleration. The gradual transition from the larger base to the smaller apex allows precision to be localized to the most critical dimensions, reducing overall manufacturing complexity while maintaining performance.
3Reliability
If the main nozzle throat has zero length or diverging duct, then the device structure is simpler, but the gas flow cannot reach supersonic speed and dielectric breakdown occurs
Solution Approach 1:
The patent uses parameter changes to transform the nozzle from a simple zero-length or diverging design to a frusto-conical converging duct with specific dimensions (L=15-80 mm, α=0°-15°). This geometric transformation creates the necessary pressure gradient and flow acceleration to achieve supersonic speeds, preventing dielectric breakdown while adding only moderate structural complexity.
Solution Approach 2:
The patent replaces complex adjustable mechanical systems with a fixed frusto-conical geometry that inherently provides the required flow control. The converging shape automatically generates supersonic flow through its geometric properties alone, eliminating the need for movable parts, actuators, or complex control mechanisms while achieving reliable dielectric withstand.
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 improved design significantly increases the dielectric recovery and reduces the risk of breakdown, confirmed by computational fluid dynamics simulations and full power tests, particularly in low short-circuit current duty operations.
Implementation Method 1
The cross-sectional area of the main nozzle throat is substantially decreasing in a direction away from the auxiliary nozzle throat, so as to form a substantially converging duct for the flow of an arc-extinguishing gas
Implementation Method 2
The main nozzle throat has a frusto-conical shape... which increases the gas density and flow velocity
Implementation Method 3
This flow pattern corresponds to an effective convective cooling of an arc and favors the interruption of the conductive path
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A gas-insulated high-voltage switching device (1) is provided, which includes an arcing contact arrangement (5) having a first arcing zone member (30) and a second arcing zone member (20) that are movable relative to one another along an axis (B). An auxiliary nozzle (40) surrounds at least a part of a second arcing contact unit (21) and has an auxiliary nozzle throat (42) having an axial extension and allowing passage at least of an end of the first arcing contact unit (31). A main nozzle throat (52) has an axial extension sideways of the auxiliary nozzle throat (42) and allows passage at least of the end of the first arcing contact unit (31). A cross-sectional area of the main nozzle throat (52) is substantially decreasing in the direction away from the auxiliary nozzle throat (42) so as to form a substantially converging duct for the flow of an arc-extinguishing gas.