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A comprehensive analysis of published experimental data and formulae for the determination of the electrical parameters of railway traction lines is performed. Several results from different authors are presented with particular attention to different assumptions and environmental conditions. Additional measurements were performed over the 5 Hz-200 kHz frequency range on a line section purposely prepared at La Spezia Railway Station (Italian State Railways). Theoretical formulae are considered and their validity is checked against experimental data. There is general accordance within common variations of the most critical parameters; calculations and measurements agree over the entire frequency range and are very accurate in the frequency range 50 Hz-50 kHz, where significant conducted disturbance lies.

The electrical arc occurring in the sliding con-1 tact between the supply contact line and the current collector 2 (pantograph) of an electrical locomotive is a fast transient 3 phenomenon able to degrade progressively the line-to-pantograph 4 contact quality and, consequently, the continuity of operation.

Power Quality indices for ripple evaluation in DC Low Voltage networks are presented and discussed. Ripple is interpreted in a more general way than a simple periodic fluctuation of network voltage due to rectifying harmonics: the indices are conceived to cope with PQ definition of several standards in terms of frequency range and related phenomena. The proposed PQ indices are implemented for real-time execution; performances are evaluated in Matlab.