Contamination Characteristics And Electric Field Distribution Of Roof Insulators On High Speed Train

With the rapid development of economy and society, the importance of high-speed railway in modern transportation system is becoming more and more prominent. Roof insulators are key equipments to ensure insulation safety of locomotive. Contamination characteristic and electric field distribution are the main indexes to evaluate the insulation performance of roof insulator. With the speeding up of electrified railway, the surrounding airflow and deposition pattern become more complex. The number of insulator shed is small for the restrictions of roof space, which makes the electric field on the creepage path extremely high. Therefore, roof insulators are the most weakness point in electric locomotive insulation. In conclusion, studying the contamination characteristics, field distribution and related factors such as deposition and shed parameters can provide references for roof insulator design, so as to guarantee the safe and stable operation of high-speed railway.Considering the locomotive roof space layout and actual working condition of roof insulators, this paper built a3D model for roof insulator in computational fluid dynamics software. Airflow distribution around the roof insulator was analyzed when the locomotive is running fast. The moving track of suspending particles in high-speed fluid was also simulated. At the same time, the influence of high-speed airflow on insulator contamination was carried out. The deposition distribution in each sheds were studied combine numerical calculation with field measurement.According to the structure feature of roof insulator, a axisymmetric model for1/2cross section of roof insulator was established. Finite element method was used to study the potential and electric field distribution of roof insulator. Comparison of potential on each shed was conducted. The electric field distribution along the creepage path was also analyzed. Finally, nonuniform wet deposition and dry band was set on the insulator surface based on the deposition characteristic. The influence of nonuniform dirty band on field distribution was carried out.The field features of equal diameter and big-small shed insulators were analyzed respectively with actual roof size.The influence of shed spacing and shed elongation on average surface electric field and air gap field were studied in equal diameter insulator. The influencing mechanism on electric field distribution of big shed and small shed were conducted in big-small shed insulator. Finally, the roof insulator shed was optimized combine field characteristics with shed parameters’regulations in Chinese railway standard.