Grounding impedance measurement method of integrated grounding system in high-speed railway roadbed section

Integrated grounding system (IGS) in china high-speed railway is formed through two long horizontal copper lines named run-through ground wire buried on both sides along the railway, which is also the longest horizontal grounding system in the world through the interconnection of railways. The grounding impedance measurement of IGS of high-speed railway is a novel, important problem to ensure the human and equipment safety. The placement approach of test electrodes for the grounding impedance measurement of the IGS in the roadbed section of high-speed railway was discussed by the simulation calculation and field test results in this study. Numerical analysis and measurement arrangement of IGS grounding impedance based on short-current lead wire was evaluated by analysing the soil structure, the distance of test electrodes and the ratio of measured grounding impedance and true grounding impedance. The test route was suggested that the potential electrode be placed on the opposite side with respect to the current electrode for measuring the grounding impedance. The suitable and convenient test electrode arrangement and the corresponding correction coefficients were obtained. Compared with the computer-aided calculation, the field test maintained acceptable measurement error. Thus, a useful measurement method was proposed for grounding impedance measurement of IGS.