The influence of high-velocity airflow on discharge characteristics of electric locomotive roof insulator

The simulative test system with the mini wind tunnel and high voltage power supply was developed for investigating the discharge of electric locomotive roof insulator. The discharge tests of two type insulators surrounded in the high-velocity airflow of 68~136 m/s at power frequency high voltage were conducted. The test results showed that the discharge of insulators in the high-velocity airflow circumstances presented the characteristics with the more discharge passages and non-surfaced discharges. Based on the numerical simulation analysis of computational fluid dynamics (CFD) method, it was confirmed that the blowout effect of high-velocity airflow plays a leading role in the conformation of discharge passage, and the low pressure airflow determined the location of initiative discharge passage. And then, within the boundary layer of insulator, the low-velocity airflow keeps the discharge arc prolongation from the blowout. The maximum boundary layer thickness over the insulator surface was near 5 mm.