Modeling and measurement of the voltage transients at the phase to phase changeover section of the Italian High Speed railway system

This paper reports the main results of a measurement campaign undertaken to characterize the transient electrical stresses faced by medium voltage cables, used in the phase to phase changeover sections of the Italian High Speed/High Capacity railway lines, powered with 2 × 25kV AC system. The study makes particular reference to the phase change point (TN San Pellegrino) located in the Scheggianico tunnel of the line Bologna - Florence since, at present, it is the only one located in tunnel in Italy and for which it was necessary to use special cable connections between conductors line and cutting equipment to comply with the minimum isolation distances allowed by railway system standards. Following two discharge phenomena, recorded during February-March 2010, which led to damage of the medium voltage (M.V.) cables and requiring their replacement, it was decided to undertake a thorough study of the problem which is partially reported in this paper.