To research the influence of rail-to-ground resistance of urban transit systems on stray current

by using the method of resistance network

we established a circuit model that each metal structure

ballast bed and ground are equivalent to resistance and rail-to-ground transition resistance. The formulations of voltage and current of each metal structure were derived. An inspection was conducted by using the CDEGS Software

and stray current and rail potential under different rail-to-ground resistance and non uniform track-to-earth resistance were discussed. The results show that the calculations remain nearly the same as simulation results with both uniform and non uniform rail-to-ground resistances. When the track-to-earth resistance is homogeneous

maximum potential deviation of stray current collection mat is 5.7 m A

which is no more than 16%. The rail-to-ground resistance is directly proportional to the insulation of rail

and the stray current is inversely proportional to the track-to earth resistance. The total stray current can reach 1 448.4 m A when the rail-to-ground resistance is 3 ?·km. The nonuniform rail-to-ground resistance will change the distribution of rail potential

but the rail voltage drop will remain unchanged. Furthermore

a sudden reduction of the rail-to-ground resistance will increase the total stray current. The results can provide a basis on which a protective system of stray current in metro is designed.