Analysis of the influence of single-line tunnel vault seepage on the electric field distribution near the cantilever insulator

The water seepage of the vault of the railway tunnel will distort the electric field distribution near the cantilever insulator, the continuous water column may directly bridge the vault and the high-voltage fittings, and the interruption of the catenary power supply may cause a large number of train delays. Therefore, it is necessary to analyze the influence of water seepage on the electric field distribution near the cantilever insulator. The leakage water of the vault is equivalent to a cylinder with a bottom diameter of 3mm, and a three-dimensional model including the vault, water column and cantilever insulator was constructed and the electric field distribution was calculated. The calculation results show that the continuous water column extending downward from the vault will distort the average electric field intensity of the residual air gap, and the increase of the length of the water column will increase the risk of arc bridging on the high-voltage side and the end of the water column of the cantilever insulator. The maximum field strength and field strength distortion rate of the surface of the cantilever insulator and the water column increase with the decrease of the distance between the insulator and the water column. With the increase of the air gap distance between the water column and the insulator, the spatial electric field distortion rate near the insulator decreases nonlinearly. The results of this paper can provide reference for the subsequent design and test verification of the vault seepage diversion channel.