Research on Surface Hydrophobicity of Insulators in the Electric Multiple Unit under Different Service Years

As the Electric Multiple Unit (EMU) runs for a long time, influenced by factors such as light and high-speed airflow, the surface roughness of the insulator increases and the molecular structure changes, which will lead to the decrease of the hydrophobicity of the insulator. This directly leads to the decline of insulator flashover voltage and seriously threatens the safety of EMU operation. This paper selected EMU pillar insulators with different service years as the research object. Hydrophobicity analysis, scanning electron microscopy analysis and Fourier infrared analysis were used to study the variation and reason of insulator surface hydrophobicity with service time. The results show that the surface hydrophobicity of insulators decreases rapidly but the trend slows down year by year with the increase of service time. Meanwhile, the results of Fourier infrared analysis show that the decrease of hydrophobicity is closely related to the content of Si-CH3 in the insulators.