Measurement of Traction Current Harmonics on the Track Circuits of the Rome – Naples High – Speed Railway

The new high speed railway lines, under construction in Italy, are electrified in 2times25 kHz - 50 Hz and, in order to avoid interference problems between traction and signaling current, make use of a signaling system based on audio frequency track circuits (AF-TC), ranging from 2.1 kHz to 16.5 kHz. Problems could arise from the fact that traction currents required by high-speed locomotives, equipped with electronic static converters, show a harmonic spectrum which includes audio frequencies. Since the tracks are means of propagation of both traction and signaling currents, interference problems in the standard operation can occur with possible impact on transportation regularity. Thus, preliminary studies of the compatibility between traction and signaling system (where the traction load is a disturbance source and the signaling circuit is a disturbance victim), under standard and failure conditions, are required. In this context, a measurement campaign on the AF-TC of the new high speed railway system Rome-Naples has been made and some results are reported in this paper