Low-frequency magnetic field in DC railway substations

A measurement campaign was carried out at Orte and S.Oreste dc substations along a high-speed trunk of the Italian railway lines. The results consist of H-field values measured at the two substations, inside the buildings (near the rectifier groups) and outside (in the area surrounding the high-voltage input line, the HV/MV transformers, and the rectifier transformers) for different load conditions during normal service. The goal of this work is to determine the H-field intensity at low and medium frequency at dc railway substations. The measurement results are post-processed to extract statistical properties (namely, average values, dispersion, and distribution histograms). This information may contribute to updating and integrating standards regarding dc substation electromagnetic environment and specific immunity tests for housed equipment.