Stray Current Interference of Metro Depot on Buried Steel Pipelines and Test Method for Rail-to-Ground Transition Resistance

Taking a domestic subway vehicle and its adjacent buried long-distance pipeline as the test research object, on-site synchronous testing of the electrical parameters related to the subway and pipeline was carried out under different operating conditions of the one-way conduction device in the entrance and exit section and the rail potential limiting device in the depot. Through comparative analysis, the characteristics of the stray current interference on the buried pipeline were clarified. At the same time, a certain in-service track section was selected and the ground transition resistance of the target track was tested using the testing method of insulation resistance of buried pipeline anti-corrosion layer. The results showed that after the bidirectional cutoff of the single conductor in the entrance and exit section, the average forward rail potential of the main line, the tracks outside the depot, and the tracks inside the depot could be reduced to less than 5 V. The level of stray current in the depot was influenced by the single conductor characteristics and the grounding method of the track in the depot. Simply cutting off the single conductor in both directions at the entrance and exit sections could not completely solve the problem of stray current in the depot. In this case, the interference range of stray current on buried pipelines caused by single conductor and grounding in the depot was less than 2.6 km. It was feasible to use the testing method of insulation resistance of buried pipeline anti-corrosion coating to test the transition resistance of in-service track to ground.