Study On The Characteristics And Mechanism Of Surface Discharge Of Insulating Medium In Airflow Environment

The insulation equipment exposed to the atmospheric environment is affected by the operating state or atmospheric movement.The surface of the insulation medium is often in a gas flow environment,and its discharge characteristics are significantly different from those of static gas.In the airflow environment,the surface of insulating equipment contains easily charged substances such as metallic dust.Under the influence of overvoltage,the accumulation of charge on the surface of the insulating medium will cause uneven distribution of the surface charge,resulting in distortion of the surface field strength.Studying the influence of airflow environment on surface discharge can provide guidance for the design and insulation coordination of high-voltage equipment in airflow environment.In this paper,the silicone rubber insulation sheet is used as the research object.Through the wind tunnel system and the surface potential test platform in the airflow environment,the surface discharge mechanism in the airflow environment is influenced by the surface potential on the discharge characteristics and the influence of the airflow on the discharge ion trajectory Explore.The main research work is as follows:(1)First,through the self-built wind tunnel system in the laboratory,the surface discharge characteristics test under the airflow environment was carried out.The optical path and electrical characteristics of the surface discharge were studied from the aspects of airflow direction and airflow velocity.In the direction of the electric field,the corona discharge light area and the discharge path are shifted along the airflow direction.The flashover voltage rises with the increase of gas velocity,and the discharge current decreases with the increase of airflow velocity;when the airflow direction is perpendicular to the electric field direction,the flashover voltage is higher than that when the airflow direction is parallel to the electric field direction.(2)Secondly,in order to verify the surface charge accumulation and dissipation characteristics of the airflow environment,a surface charge test platform for the airflow environment was built,and the in-depth study of the surface charge dissipation conduction mechanism and transport characteristics under the airflow environment showed that the surface charge under the airflow environment The distribution of is not in the center of the insulating medium,the accumulation area will shift along the airflow,and the larger the airflow speed,the more serious the offset;at the same time,compared with the static airflow environment,the surface charge dissipation in the airflow environment will accelerate,the faster the airflow speed the faster the surface charge dissipates;at the same time,the two methods of dissipation of the conductive body dissipation of the surface of the insulating medium and the gas side neutralization are discussed in the airflow environment.The test shows that the airflow will change the pressure on the gas side and the surface of the insulating medium.The temperature makes the conduction mechanism of the insulating medium change under the airflow environment,and the surface charge is easier to dissipate than in the static environment.(3)Finally,the effect of surface charge accumulation and dissipation characteristics on the flashover voltage under the airflow environment was studied.By injecting charge on the surface of the insulating medium under the airflow and conducting the surface flashover test,it was found that after the charge was injected on the surface of the insulating medium,will cause the flashover voltage to drop,but the flashover voltage will increase as the airflow speed increases,and the flashover path will also bend.This is because the airflow causes the surface charge accumulation area to shift,which proves that the airflow will cause discharge ions to occur deflection and blow away;at the same time,the rate of charge dissipation on the surface of the insulating medium increases,the electron flux on the surface of the insulating medium decreases,and the amount of accumulated surface charge decreases,thereby weakening the surface electric field of the insulating medium.Therefore,the deflection and blow-off effects of electrons and the reduction in the amount of accumulated surface charge are the main factors that cause the rise of the flashover voltage between the needle plate electrodes in the high-speed airflow environment.