Research on A Novel Method for Measuring Rail-to-Earth Resistance in Subway Tunnels

Focus on the accuracy issues of the standard recommended rail-to-earth resistance measurement method, particularly when measuring section is short, this paper proposes a novel method utilizing a frequency-variable AC source, which provides a new idea for the research of new measurement method of rail-to-earth resistance and is verified by simulation. Compared with the traditional method, this method is applicable for measuring rail-to-earth resistance in both DC and AC power supply systems and there is no need to measure the rail longitudinal resistance and the current in the rail. An equivalent rail model is developed using ATP-EMTP to validate the accuracy and performance of the new method. Simulation results demonstrate that this method significantly improves the accuracy compared to the traditional method. Additionally, based on the calculation formula of the new method, utilizing filtering technology during data acquisition may render the new method less susceptible to field electrical interference.