Analytical study on lightning overvoltages of rail track and railway signalling equipment

Abstract

The development of the effective and economical protection measures is vital for the railway signalling systems because the lightning damages cause the disruption of the railway transportation systems. In general, the railway signalling systems are set up at a wayside and directly connected to the rails through cables. The lightning surges can invade the railway signalling systems via the cables and cause damages to the systems. Accordingly, clarifying the propagation characteristics of lightning surges along the rails is essential to develop the lightning protection measures for the railway signalling systems. We have carried out the field tests to examine both surge impedance and surge propagation velocity of the rails. This paper proposes a calculation model of the surge propagation characteristics along the rails. The results of surge impedance and surge propagation velocity calculated by the proposed model almost agree with the experimental results. Moreover, this paper proposes a calculation model of the lightning overvoltages on the railway signalling equipment. The calculation model consists of the rail model and the equivalent circuit model of signalling equipment. We indicated the validation of the calculation model of the railway signalling equipment due to the comparison with the results of the field test. This model is applicable to the development of lightning protection measures for the railway signalling systems.