Finite element calculation of leakage resistance and distributed capacitance of rail to earth in ballastless track

The leakage resistance of rail to earth is an important parameter of electrified railways, and it directly affects the characteristics of traction return current and railway signal track circuit. High speed railways mainly adopt the ballastless track in China, whose rail leakage resistance is very different compared to the resistance in the ordinary railway ballast track condition, usually has a much larger value. Furthermore, the distributed capacitance effect of rail to earth in the ballastless track condition should not be ignored. The rail has an anharmonic cross section, and is installed on the spacing support of the concrete integrated ballastless bed. Neither the leakage resistance of rail to earth can be calculated using a practically simple theory or method, nor the distributed capacitance of rail can be accurately calculated using the model for thin circular conductor of overhead transmission lines. This paper presents the test results of the rail leakage resistance and the distributed capacitance in Jin-Qin (Tian jin city Qin huangdao city) high speed railway of China. At the same time, according to the specific condition of the ballastless track, a finite element calculation model of the electromagnetic field has been established using Comsol Multiphysics simulation software, which includes the rail, the concrete track bed, roadbed and the earth. The leakage resistance and distributed capacitance of rail to earth are calculated using this finite element method. The calculation results and the measured results are compared with each other. Error factors between them have been analyzed. Results show that, the finite element model for calculating the leakage resistance and the distributed capacitance of rail to earth is an effective approach. The field measured data can be used in the future for the related analysis and calculation of traction networks and track circuits.