Gas-Insulated Switchgear Mixture for Low-Temperature Arc Extinction
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Solution Overview
Problem
Current high-voltage equipment insulation gases, such as SF6, have high global warming potential and liquefy at subzero temperatures, requiring auxiliary heating that complicates equipment design and increases environmental impact.
Innovation Solution
A gas mixture of heptafluoroisobutyronitrile, carbon dioxide, and a high content of oxygen (above 26 mol%) is used for electrical insulation and arc extinction, reducing liquefaction temperature without external heating, maintaining low environmental impact and insulating properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SF6 gas is used for electrical insulation and arc extinction, then dielectric strength and thermal conductivity are improved, but global warming potential increases significantly
Solution Approach 1:
The patent uses a composite gas mixture comprising heptafluoroisobutyronitrile (2-10% by volume), carbon dioxide (70-90% by volume), and oxygen (10-30% by volume). This composite approach combines the high dielectric strength of heptafluoroisobutyronitrile with the low GWP of CO2 and the arc extinction enhancement of oxygen, achieving SF6-level performance with dramatically reduced environmental impact (GWP < 150 compared to SF6's GWP of 23,500).
Solution Approach 2:
The patent optimizes the volumetric composition parameters of the gas mixture to achieve optimal performance. By adjusting the proportions of heptafluoroisobutyronitrile (2-10%), CO2 (70-90%), and O2 (10-30%), the mixture achieves dielectric strength and arc extinction capabilities comparable to SF6 while maintaining GWP below 150. The specific parameter ranges are determined through experimental optimization to balance electrical performance and environmental impact.
2Object-generated harmful factors
If CO2-based gas mixtures are used to reduce GWP, then environmental impact is reduced, but liquefaction temperature increases at subzero conditions
Solution Approach 1:
The patent modifies the compositional parameters of CO2-based gas mixtures by adding oxygen (10-30% by volume) to the heptafluoroisobutyronitrile and CO2 mixture. This parameter change effectively lowers the liquefaction temperature of the gas mixture, enabling operation at subzero temperatures without phase change. The oxygen addition disrupts the CO2-heptafluoroisobutyronitrile interaction that causes premature liquefaction, extending the operational temperature range to below -40°C while maintaining low GWP.
3Reliability
If auxiliary heating is added to prevent liquefaction at subzero temperatures, then operational reliability is improved, but device complexity and energy consumption increase
Solution Approach 1:
The patent makes the gas mixture itself self-service by formulating it with oxygen-containing components that inherently prevent liquefaction at subzero temperatures. The gas mixture autonomously maintains its gaseous state and electrical insulation properties without requiring external heating systems, controllers, or power supply, thereby eliminating the complexity and energy consumption associated with auxiliary heating while ensuring operational reliability in cold environments.
4Productivity
If oxygen content is increased in the gas mixture, then arc extinction capability is improved, but dielectric strength may be reduced
Solution Approach 1:
The patent optimizes the oxygen content parameter within the range of 10-30% by volume in the gas mixture. This parameter optimization achieves the optimal balance between arc extinction capability and dielectric strength. The oxygen enhances electron attachment and reduces electron avalanche, improving arc extinction, while the heptafluoroisobutyronitrile and CO2 maintain high dielectric strength. The specific oxygen concentration range is determined through experimental optimization to simultaneously satisfy both requirements.
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 gas mixture effectively lowers liquefaction temperature by more than 4 degrees at high pressures, eliminating the need for auxiliary heating and maintaining insulation and arc extinction capabilities comparable to SF6, while reducing environmental impact.
Implementation Method 1
electrical insulation and electric arc extinction are performed by a gaseous medium
Implementation Method 2
electrical insulation and electric arc extinction are performed by a gaseous medium
Data Source
AI summary
The present application concerns a medium- or high-voltage equipment including a leaktight enclosure in which there are located electrical components and a gas mixture for providing electrical insulation and/or for extinguishing electric arcs that are likely to occur in the enclosure, the gas mixture including heptafluoroisobutyronitrile, carbon dioxide, and a high content of oxygen.