Effect of High-speed Airflow on the Surface DC Discharge Characteristics of the Needle Plate

Insulating equipment exposed to the atmosphere is affected by operating state and atmospheric motion. The surface of the insulation medium is often in an airflow environment, and its discharge characteristics will vary greatly from those in the static air. In this paper, the silicone rubber insulation sheet was taken as the research object. The surface flashover characteristics of the insulation medium in the airflow environment were tested by the wind tunnel system. It is found that the corona discharge light region and the discharge path are offset along the airflow direction when the airflow direction is perpendicular to the electric field direction. The trajectory changes of particles in the insulation medium surface, gas thin layer and gas under airflow environment were analyzed. It is considered that the airflow causes the trajectory of the particles to deflect and causes a large number of electrons and particles to be blown off the insulation medium surface, so that the concentration of electrons and particles on the insulating medium surface decreases, which weakens the electric field of the steamer head and makes the development of the steamer more difficult. At the same time, the airflow environment changes the way of charge accumulation on the insulation medium surface and the source of charge. As the airflow velocity increases, the charge dissipation rate on the insulation medium surface increases, and the normal and tangential electron fluxes on the dielectric surface decrease, resulting in the decrease of surface charge accumulation, which weakens the surface electric field of the insulation medium. The deflection and blow-off effects of electrons and the reduction of surface charge accumulation are the main factors leading to an increase in the flashover voltage of the pinhole electrode under a high-speed airflow environment. © 2019 Chin. Soc. for Elec. Eng.