EVALUATION OF THE RISK DUE TO LIGHTNING STRIKES IN A HIGH-SPEED RAILWAY CATENARY

Because of its length, the catenary is probably the part of the infrastructure which is the most exposed to lightning strikes: it is a very conductive part, with a significant height, sharp parts and high voltages applied on it. For that reason, different protection schemes are adopted. Surge arresters are installed to limit the over-voltages in the substations, along the catenary and onboard the trains. In addition, an air-termination network (composed of lightning rods or overhead wires, which are grounded) are installed in the substations. The implementation of these schemes normally follows in-house guidelines, established by each infrastructure manager to ensure the compliance with the standards. The physical interpretation of the equivalent area and the expected number of flash strikes is sometimes missing. This paper intends to provide a physical perspective to this problem, using the concept of volume of attraction of each conducting element and linking it to the notion of equivalent area. A specific study case taken for the Madrid-Barcelona 25kV 50Hz high-speed line (Spain) is used to illustrate these concepts.