Gas-Insulated Load Break Switch Radial Arc Quenching
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Solution Overview
Problem
Existing low- and medium-voltage load break switches face challenges in reliably extinguishing arcs under difficult conditions while maintaining a compact and cost-effective design, particularly when dealing with high-rated currents and voltages up to 52 kV.
Innovation Solution
A gas-insulated load break switch with a pressurizing system that pressurizes a quenching gas to a subsonic flow pattern, blown radially inwardly onto the arc through a nozzle system, maintaining a quenching pressure below 1.8 times the ambient pressure, and using alternative insulation gases with lower global warming potential than SF6.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SF6 gas is used for arc quenching with high pressure build-up, then arc extinction reliability is improved, but environmental impact increases and device complexity increases
Solution Approach 1:
The patent changes the physical parameters of the quenching process by using alternative gases (such as air, nitrogen, or CO2) instead of SF6, and by optimizing pressure build-up to subsonic flow conditions (Mach number < 0.3). This allows effective arc extinction while eliminating the environmental harm associated with SF6 greenhouse gas emissions.
Solution Approach 2:
The patent employs readily available, inexpensive alternative gases (air, nitrogen, CO2) that can be easily replenished or regenerated, replacing the expensive and environmentally problematic SF6 gas. These gases have no harmful environmental impact and can be used in open or semi-closed systems.
2Reliability
If high pressure build-up is used for arc quenching, then arc extinction reliability is improved, but drive requirements and device complexity increase
Solution Approach 1:
The patent fundamentally changes the pressure parameter from high-supersonic conditions to moderate-subsonic conditions (maintaining Mach number below 0.3). This parameter change reduces the force requirements for the drive mechanism, allowing simpler, more reliable actuators to be used while maintaining effective arc quenching performance.
Solution Approach 2:
The patent reduces reliance on complex mechanical pressurization systems by using alternative gases that achieve effective quenching at lower pressures. This substitution simplifies the mechanical drive system, reducing the need for high-force actuators, robust sealing mechanisms, and complex pressure management components.
3Speed
If supersonic flow conditions are used for arc blowing, then arc extinction speed is improved, but gas pressure requirements and energy consumption increase
Solution Approach 1:
The patent optimizes the flow velocity parameter by maintaining subsonic conditions (Mach number < 0.3) rather than achieving supersonic flow. This parameter optimization demonstrates that effective arc extinction can be achieved at lower velocities when using alternative gases with appropriate thermodynamic properties, thereby reducing the kinetic energy requirements and overall energy consumption of the switching 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 solution enables reliable arc extinction with reduced pressure build-up and drive requirements, allowing for efficient arc cooling and quenching even with alternative gases, thus improving thermal interruption performance and reducing environmental impact.
Implementation Method 1
a pressurizing system having a pressurizing chamber arranged within the housing volume for pressurizing a quenching gas to a quenching pressure during the current breaking operation
Implementation Method 2
blowing, by the nozzle system, the pressurized quenching gas in a subsonic flow pattern from the pressurization chamber onto the arc formed in the quenching region
Implementation Method 3
blowing, by the nozzle system, the pressurized quenching gas in a subsonic flow pattern from the pressurization chamber onto the arc formed in the quenching region, thereby blowing the quenching gas from an off-axis position predominantly radially inwardly onto the quenching region
Implementation Method 4
SF6 is used as the quenching gas because of its excellent dielectric and cooling properties
Implementation Method 5
SF6 is used as the quenching gas because of its excellent dielectric and cooling properties
Data Source
AI summary
A gas-insulated low- or medium-voltage load break switch includes: a housing defining a housing volume for holding an insulation gas at an ambient pressure; a first arcing contact and a second arcing contact arranged within the housing volume, the first and second arcing contacts being movable in relation to each other along an axis of the load break switch and defining a quenching region in which an arc is formed during a current breaking operation; a pressurizing system having a pressurizing chamber arranged within the housing volume for pressurizing a quenching gas from an ambient pressure p0 to a quenching pressure pquench during the current breaking operation; and a nozzle system arranged within the housing volume for blowing the pressurized quenching gas in a subsonic flow pattern from the pressurization chamber onto the arc formed in the quenching region during the current breaking operation. The nozzle system includes at least one nozzle arranged for blowing the quenching gas from an off-axis position predominantly radially inwardly onto the quenching region.