Influence of high-speed airflow on surface discharge characteristics of insulator

The simulative test system with the mini wind tunnel and high voltage power supply was developed for investigating the discharge characteristics of insulator in the high-speed airflow circumstances. The discharge tests of two downscaled insulators under different high airflow speed and power frequency high voltage are conducted. The test results show that the discharge characteristics of insulators under the high-speed airflow present the multi discharge passages and non-surfaced discharges. Based on the compressible Navier-Stokes equation of computational fluid dynamics and finite element analysis method, airflow velocity and pressure distributions around insulator are computed. The high airflow speed and low airflow pressure in the sideward of insulator is presented. According to these results, it is confirmed that the blowout effect of high-speed airflow plays a leading role in the conformation of discharge passages or arcs and the low pressure airflow dominates the flashover or discharge initial location. And then, the boundary layer effect along the insulator surface keeps the discharge passage prolongation from the blowout.