Study on Breakdown Characteristics and Attenuation Characteristics of Air Mixed Gas

Abstract

Nowadays, the global demand for environmental protection and energy saving is getting higher and higher. In the past, SF6 gas was regarded as an environmentally unfriendly gas in the circuit breaker with SF6 gas as the insulating medium. In order to save energy and reduce emissions, this paper uses clean and environmentally friendly air as the arc extinguishing medium. The gas mixture studied contains N2, O2 and CO2. Through two approximate values of Boltzmann equation, we obtain the electron energy distribution function of air mixed gas under different electric field reduction conditions. By studying the changes of ionization and adsorption coefficients of particles under various collision conditions, we obtained the conversion breakdown field strength (E/N) Cr of air mixture. An arc attenuation model is built to characterize the arc attenuation characteristics using the prior transport characteristics as input. The arc attenuation process is broken down into three steps: heat recovery, pre-ignition, and arcing. All of these phases are determined by the changes in axial temperature and arc conductance over time. Analysis is done on the air and nitrogen thermal recovery and pre-dielectric recovery phases. This study explores the use of clean dielectrics to ensure optimum performance of primary equipment in the power system, based on current circumstances.