Study on Characteristics of Surface Discharge of Silicone Rubber under High-speed Airflow

High-speed train roof insulators are the key equipment for train high-voltage isolation and pantograph mechanical support. Their good insulation performance is the basic condition to ensure the safe operation of trains. With the rapid development of high-speed trains, the speed of trains is getting faster and faster. The silicone rubber insulators on the train roofs are exposed to the atmospheric environment. The silicone rubber insulators are affected by operating conditions and atmospheric movement, and the surface of the insulating medium is often in an air current environment. High-speed trains run in the atmospheric environment and move relative to the airflow. Compared with static gas discharge, frequent collisions between molecules and charged particles in the flowing gas in the direction of the airflow will inevitably have a great impact on the surface discharge process of the insulator. Silicone rubber insulators have a big difference between the creeping discharge characteristics under high-speed airflow and the creeping discharge characteristics under static conditions. When the discharge distance is the same, the creeping discharge voltage of the insulating medium is lower than the breakdown voltage of the pure air gap. Therefore, the creeping discharge of the insulator under high-speed airflow is more likely to occur than the discharge of the air gap, which leads to the occurrence of the discharge accident of the insulator on the train roof. Once an insulation accident occurs on the train roof insulator, it will pose a great threat to people's lives and property. The external insulation system of the train roof is the weak link in the insulation performance of the train. Therefore, it is necessary to carry out related research on the creeping discharge characteristics of the roof silicone rubber insulators under high-speed airflow, and to prove the creeping discharge characteristics of the high-speed train insulators. This is an important issue that urgently needs to be resolved during the safe operation of high-speed railways. In this paper, silicone rubber is used as the research object, and the surface discharge test is carried out on the silicone rubber insulating sheet through the wind tunnel system. Through experiments, the creeping discharge voltage of silicone rubber under different airflow speeds, the discharge path of the silicone rubber surface under different airflow speeds, and the change characteristics of silicone rubber surface temperature under different airflow speeds are obtained; the creeping discharge change law of silicone rubber with the change of airflow speed is obtained. Through theoretical analysis reveals the creeping discharge characteristics of silicone rubber under high-speed airflow. This study provides theoretical support for the external insulation design of high-speed trains to ensure the safe and stable operation of high-speed trains.