Measurement of AT electric railway system currents at power-supply frequency and validation of a multiconductor transmission-line model

An electric traction system supplied at 2 × 25 kV with autotransformers (ATs) is considered. The conductors´ arrangement is that of the new European High Speed Railway Line (HSRL) under construction: The overhead supply conductors in contact with the train pantograph are connected to a symmetrical circuit (the feeder) with the purpose of current balancing; the traction return current flows from the rolling stock axles back to the supply (i.e., substation) through the traction rails and additional return conductors. The test campaign carried on the Rome-Naples HSRL allowed the validation of the multiconductor transmission line model used for system analysis. Measurements were performed in normal system configuration (2 × 25-kV supply) and degraded configuration (1 × 25 kV with AT and feeder not operating). Metrological issues (accuracy and consistency) are detailed for the presented results.