Signalling system interferences due to railway electric substation failures on Italian conventional railwaynetworks

Nowadays the problem of interferences that involve railway signaling systems is becoming more and more important in some railway networks. New electrical and electronic applications in power supply increase the electromagnetic compatibility problems in particular signalling systems like the coded current automatic block (BACC), installed on about 4400 km of Italian conventional railway lines. Remaining in the sphere of a traditional 3 kV D.C. traction system and apart from its interaction with other types of system, interferences with signalling systems can be produced by the traction inverters installed on the board of the rolling stock and by the electrical substation (ESS) converters. In this paper critical working conditions of the ESS converters, due to the presence of internal failures, is analysed. A consequence of these internal failures is that 50 Hz harmonic current can be produced on the D.C. side and disturb the BACC operating