Hideki Arai

Estimation of lightning overvoltages according to lightning conditions and effect on decreasing lightning hazards due to SPD for railway signalling systems

Effective and economical lightning protection measures are necessary for railway signalling systems because suspended operation or train delays due to lightning damage may cause social disruption. The authors have measured lightning overvoltages on railway signalling cables laid at ground surface, overhead power lines and rails in the field to enable quantitative analysis of the frequency of lightning overvoltage occurrence from 2010 to 2013. We investigated the correlation of lightning overvoltages on signalling cables, power lines and rails with lightning conditions, such as the stroke current and the strike position, and derived the equations for estimation of the lightning overvoltages according to the lightning conditions. Moreover, we examined the effect on decreasing lightning overvoltages due to SPD attached on railway signalling cables and evaluated the effect on decreasing lightning hazards for railway signalling systems.

The lightning risk evaluation for railway signalling systems based on observation of lightning overvoltages

Effective and economical lightning protection measures are necessary for railway signalling systems because suspended operation or train delays due to lightning damage may cause social disruption. The authors measured lightning overvoltages on railway signalling cables laid at ground surface, overhead power lines and rails in the field to enable quantitative analysis of the frequency of lightning overvoltage occurrence. Moreover, we investigated the correlation of lightning overvoltages on signalling cables, power lines and rails with lightning conditions, such as the stroke current and the strike position. This paper describes the lightning risk evaluation for railway signalling systems against lightning conditions.

Calculation model to evaluate effects of lightning protection measures on railway signalling equipment

The development of the effective and economical protection measures is very important for the railway signalling systems because the lightning damages cause the disruption of the railway transportation systems. The authors have conducted the field tests to investigate the surge parameters along the rails and proposed a calculation model of surge propagation characteristics along the rails. In this paper, we propose a calculation model for lightning overvoltages on the railway level crossing system as typical railway signalling equipment. Moreover, this paper indicates the evaluation results of lightning protection effects by using the calculation model.

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

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.

Experimental study on electrical characteristics of grounding method for Shinkansen lines

In Japan, the groundings of signalling and communication equipment are installed for various purposes. Therefore, many groundings are installed especially around the signalling and communication house where the equipment are arranged intensively. On the other hand, in Europe, there are many cases where groundings are commonly used by various purposes. In this paper, the authors performed experiments to compare the effect of the individual grounding method and the common grounding method, and examined whether or not the authors are able to connect each grounding of the signalling and communication equipment including power equipment such as high voltage distribution cubicle and substation apparatus used in the high speed railways in Japan.

Lightning overvoltage of rails and signalling cables in electrified/non-electrified section

Effective and economical lightning protection measures are necessary for the railway signalling systems because suspended operation or train delays due to lightning damage may cause social disturbance. Railway signalling systems are mainly composed of signalling cables laid on the ground surface, rails and overhead power lines. The authors have measured lightning overvoltage of these components of railway signalling systems in the field. The measurement in a non-electrified section was conducted from 2010 to 2013, and the measurement in an electrified section has just started from 2015. This paper describes the measurement results in the electrified section and the correlation between lightning overvoltages of the components and lightning conditions, such as the stroke current and the strike position. Moreover, this paper indicates the difference of lightning overvoltages of signalling cables and rails between the electrified section and the non-electrified one.

Evaluation of Level Crossing Lightning Protection Measures

Building up effective and economical countermeasures is needed to prevent lightning damage to railway signalling systems. Therefore, we measured the wayside ground potential distribution when a rail potential rise was caused by injecting a lightning surge current into a rail. Moreover, we injected a lightning surge current into the rail or wayside ground, raising their potential in order to measure the lightning overvoltages on a level crossing so that basic insulation design data could be obtained. This paper demonstrates that an effective countermeasure is to earth lightning protective devices, which are attached to the electronic train detectors on a level crossing to suppress any lightning overvoltages.