Medium-Voltage Load Break Switch With Self-Blast Arc Extinguishing
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Solution Overview
Problem
Current alternatives to sulfur hexafluoride (SF6) for medium-voltage switch-disconnectors do not replicate the arc extinguishing behavior and insulation properties of SF6, requiring design changes and additional mechanical effort for effective operation.
Innovation Solution
A medium-voltage switch-disconnector design featuring a hollow contact system with a self-blowing volume and a movable stamp that reduces compression volume, utilizing the energy of the arc to flow insulating gas into the arc space, cooling and extinguishing it, and using the arc's energy to build pressure for efficient arc extinguishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If alternative insulating gases (air, CO2, nitrogen, fluoroketones, fluoronitriles) are used to replace SF6, then environmental compatibility is improved, but arc extinguishing behavior and insulation properties deteriorate
Solution Approach 1:
The patent pre-fills the hollow contact with insulating gas at a specific pressure before switching operations. This preliminary action ensures that when the arc forms, there is already sufficient insulating gas available to extinguish the arc effectively, compensating for the inferior arc extinguishing properties of alternative gases compared to SF6.
Solution Approach 2:
The patent changes the pressure parameter of the insulating gas by using a higher pressure in the hollow contact compared to conventional designs. This parameter change enhances the density and insulating capability of alternative gases, improving their arc extinguishing behavior to approach SF6 performance while maintaining environmental benefits.
2Reliability
If design changes are made to achieve same insulation behavior with alternative gases, then arc extinguishing performance is improved, but device complexity increases
Solution Approach 1:
The patent embeds a hollow contact (containing insulating gas at high pressure) within the existing switch-disconnector structure. This nesting approach integrates the improved insulation system into the conventional design without requiring complete system redesign, thus improving insulation behavior while limiting the increase in device complexity.
Solution Approach 2:
The hollow contact is designed to be self-contained, pre-filled with insulating gas at the appropriate pressure. This self-service design eliminates the need for complex external gas supply systems, pressure regulation mechanisms, or monitoring systems, thereby improving insulation behavior without significantly increasing device complexity.
3Reliability
If mechanical effort is increased to blow arc with alternative gases, then arc extinguishing is improved, but energy consumption increases
Solution Approach 1:
The patent converts the harmful thermal energy of the arc into a beneficial effect by using the arc's own heat to vaporize the insulating gas, creating a high-temperature plasma flow that helps extinguish the arc. This reduces the need for additional mechanical blowing energy, as the arc's energy is utilized productively.
Solution Approach 2:
The patent replaces part of the mechanical blowing system with a thermal-gas-dynamic system. Instead of relying solely on mechanical pressure to blow the arc, the system uses the thermal energy of the arc to generate a gas flow that assists in arc extinguishing, thereby reducing mechanical energy consumption.
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
This design reduces mechanical energy required for arc extinguishing, enhances switching performance, and maintains the arc extinguishing behavior of SF6 with reduced mechanical effort and drive energy, using the arc's energy to build pressure and cool the arc effectively.
Implementation Method 1
insulating gas, which is present in the compression volume, to flow through the contact hole into the arc space by reducing the compression volume, whereby this insulating gas, on the one hand, cools an arc present there
Implementation Method 2
heats up and flows into the self-blowing volume, which is in the insulating material nozzle is present. Once a critical pressure and a critical temperature have been reached both in the arc space and in the self-blow volume
Implementation Method 3
the energy of the arc itself is used in combination with a blowing from the compression volume to build up pressure
Implementation Method 4
the compression volume is limited on a side facing away from the contact bore by a stamp that is movably mounted with respect to the hollow contact system. When the contacts open, the stamp performs a translational movement with respect to the hollow contact system, which causes a reduction in the compression volume
Implementation Method 5
Once a critical pressure and a critical temperature have been reached both in the arc space and in the self-blow volume, this insulating gas flows back into the arc space and cools it so that the arc goes out when the alternating current subsequently crosses zero
Data Source
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AI summary
The invention relates to a medium-voltage circuit breaker, comprising: - two contacts mounted so as to be movable relative to one another, a first of the contacts being a pin contact (18) and the second of the contacts being a hollow contact (4) having a contact bore (16) for accommodating the pin contact (18), - a hollow contact system (6) which comprises the hollow contact (4) and a compression volume (20), - an arcing chamber (14), - an insulating material nozzle (8) which surrounds at least one of the contacts (4, 18) and comprises a self-blast volume (10) for accommodating an insulating gas, the self-blast volume (10) having an opening (12) to the arcing chamber (14), - a plunger (24) which is movably mounted with respect to the hollow contact system (6), wherein - the contact bore (16) opens into the arcing chamber (14) on a first side (17) and is connected to the compression volume (20) on a second side (19), - the compression volume (20) is delimited by the plunger (24) on a side (22) facing away from the contact bore (16), - the plunger (24) performs a translational movement (26) with respect to the hollow contact system (6) during an opening movement of the contacts (4, 18) and causes the compression volume (20) to reduce.