Circuit Breaker Liquid Injection for Arc Extinction
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Solution Overview
Problem
Existing circuit breakers using SF6 gas face challenges with precise liquid injection control, leading to potential overpressure and reduced performance, especially at high temperatures, and existing solutions for low-temperature applications are not suitable for medium to high-voltage systems.
Innovation Solution
A device for injecting a fluorinated liquid into the arc zone of a circuit breaker, which includes a compression chamber and a blowing chamber, with a liquid injector system controlled by sensors to manage the injection timing and quantity, allowing for precise liquid delivery regardless of temperature, using fluoronitriles, fluorinated oxiranes, or fluoroketones with high boiling points and low Global Warming Potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid is injected into the arc zone during contact separation, then breaking performance is improved, but pressure control becomes difficult leading to potential overpressure and destruction of cut-off zone elements
Solution Approach 1:
The invention divides the single injection process into two distinct phases: a first injection phase that occurs before contact separation to establish baseline liquid presence, and a second injection phase that occurs during contact separation to enhance breaking performance. This segmentation allows pressure to be managed in stages rather than all at once, preventing dangerous pressure spikes while maintaining effective arc extinction.
Solution Approach 2:
The first injection of liquid occurs in advance, before the contacts begin to separate. This preliminary action ensures that liquid is already present in the arc zone when the arc forms, optimizing breaking performance without requiring excessive liquid injection during the critical separation moment, thereby controlling pressure more effectively.
2Ease of manufacture
If liquid reservoir is placed around the main contact, then liquid injection is simplified, but heating causes complete vaporization or overpressure evacuation reducing liquid volume and injection effectiveness
Solution Approach 1:
The liquid injection system is divided into two separate reservoirs: a first reservoir positioned away from the main contact that experiences less thermal heating, and a second reservoir positioned closer to the contact. This segmentation allows the first reservoir to store liquid that won't be completely vaporized by heat, ensuring liquid availability for injection, while the second reservoir can be optimized for direct injection into the arc zone.
Solution Approach 2:
The first reservoir acts as an intermediary storage that protects liquid from direct thermal exposure. Liquid is stored in this cooler reservoir and then transferred or injected into the arc zone, serving as a thermal buffer that prevents complete vaporization while still delivering liquid to where it's needed for effective breaking.
3Reliability
If fluorinated liquid is used for breaking, then dielectric properties are improved and environmental impact is reduced, but injection precision must be maintained to avoid overpressure
Solution Approach 1:
The total liquid injection quantity is segmented into two controlled phases: a first injection phase with a controlled volume injected before contact separation, and a second injection phase with a different controlled volume injected during separation. This segmentation enables precise control of the total fluorinated liquid quantity, ensuring optimal dielectric strength is achieved without exceeding pressure limits that would cause overpressure problems.
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
Enhances breaking performance by maintaining dielectric strength and reducing environmental impact, with the ability to operate effectively across a wide temperature range, including above 72°C, without the risks of overpressure or reduced performance.
Implementation Method 1
a device making it possible to inject into the arc zone, during the separation of the contacts, a liquid whose vaporization will help with the breaking
Implementation Method 2
a liquid whose vaporization will help with the breaking
Data Source
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AI summary
The invention concerns a current interrupter chamber (1) for a medium or high voltage circuit breaker extending along a longitudinal axis (XX') and comprising: - a pair of arcing contacts (4, 5), at least one of which (5) is movable along the longitudinal axis (XX' ), - an arc blowing nozzle (6), - a blowing chamber (7) of which the volume V2 is fixed and that opens inside the blowing nozzle, - a compression chamber (8), arranged substantially behind the blowing chamber, and means (73, 81) for making the inner volume of said compression chamber (8) and that of the blowing chamber (7) communicate, - means (14, 15, 50), disposed substantially behind the compression chamber (8), for supplying a liquid, either in the compression chamber (8), or directly in the blowing chamber (7).