Breakdown Effects of Dissolved SF&lt;sub&gt;6&lt;/sub&gt; Gas on Uniform Field in Perfluorocarbon Liquid

Miyagi, Katsunori; Kagami, Kenji; Sugimoto, Toshirou

doi:10.1541/ieejfms1990.119.3_311

Cited by 2 publications

(1 citation statement)

References 2 publications

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“…In Equation ( 13), the generated water bubbles contain highly electrolytic materials such as H 2 SiF 6 , and the HF gas absorbed by the epoxy resin changes the surface resistance, which may lead to a significant drop in the shock flashover voltage. For the mixtures of SF 6 and perfluorocarbons, the C atoms in the perfluorocarbons react with the F atoms of the SF 6 gas to form inert perfluorocarbon compounds [28]. The nozzle's wear is manifested as the "burning" of Teflon, and reaction formula ( 14) occurs, resulting in the reaction of PTFE and SF 6 to generate CF 4 , carbon fluoride, SF 4 , etc.…”

Section: Discharge Defectsmentioning

confidence: 99%

Evolution of Elements on Electrode Surfaces in Gas-Insulated Systems under Electrical Heating

Sun

Zhang

et al. 2022

Coatings

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Accidents always occur in gas-insulated switchgears (GIS) and gas-insulated lines (GIL) since filmed joint electrodes are produced when internal gases react with the electrode’s surface when there is a discharge or when internal electricals overheat. To solve the problem, this paper analyzed the evolution of elements on the contact electrode. The reaction of the SF6 and electrode’s surface under breakdown currents and overheating conditions was obtained, and the discharge time and discharge current effects upon the transfer of the element were proposed. It was found that the mobility of the F element on the electrode’s surface typically increases after electrical heating. The number of interruptions and short-circuit currents are important factors affecting the transfer of the F element to the electrode. The flashover current is the essential factor that accelerates the transfer of the F element to insulating materials. Frequent switching is a main factor that accelerates the transfer of the F element to the contact. It was also found that Al has little correlations with the breaking process, and metal fluorides become the main components on the electrode’s surface under discharge heating. The research provides a theoretical basis and data support for GIS/GIL surface optimization treatments and the improvement of fault detection methods.

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Section: Discharge Defectsmentioning

confidence: 99%

Evolution of Elements on Electrode Surfaces in Gas-Insulated Systems under Electrical Heating

Sun

Zhang

et al. 2022

Coatings

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Characterization of the Airflow Distribution near a Circuit Breaker’s Cu-Ag-Alloy Electrode Surface during and after Breakdown

Sun,

Shao,

Zhang

et al. 2024

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Circuit breakers, affected by multiple lightning strikes after the breaker has been tripped, can break down again, which will reduce the life of the circuit breaker and threaten the stable operation of the power system. Aiming at this problem, this research obtained the temperature diffusion process of the inrush current process of the circuit breaker’s opening and breaking, using the Schlieren technique combined with existing image recognition technology to obtain the temperature characteristics of the airflow in the air gap of the contact, as well as the characteristics of the flow of air itself. The results of the study show that the circuit breaker breakdown process generates a shock wave with a velocity approximately equal to the speed of sound under the same conditions. The maximum velocity of the airflow boundary diffusion is about one-quarter of the speed of sound under the same condition, and it decays very fast, reducing to the airflow drift velocity within 10 ms after breakdown. The maximum temperature of the thermals is concentrated between 6000 K and 8000 K, and the temperature change is approximately inversely proportional to the square of the time. This research provides the basis for the design of a circuit breaker’s contact structure, opening speed optimization method, interrupter chamber, and insulation design optimization.

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Breakdown Effects of Dissolved SF<sub>6</sub> Gas on Uniform Field in Perfluorocarbon Liquid

Abstract: Tablel. Typical properties of PFC liquid.

Cited by 2 publications

References 2 publications

Evolution of Elements on Electrode Surfaces in Gas-Insulated Systems under Electrical Heating

Evolution of Elements on Electrode Surfaces in Gas-Insulated Systems under Electrical Heating

Characterization of the Airflow Distribution near a Circuit Breaker’s Cu-Ag-Alloy Electrode Surface during and after Breakdown

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