Keywords: railway dynamics, multibody systems, pantograph-catenary interaction, contact forces, cross-wind, track irregularities.

The limitation on the top velocity of high-speed trains concerns the ability to supply the proper amount of energy required to run the engines, through the pantograph-catenary interface. As a result of the loss of contact not only the energy supply is interrupted but also arching between the collector bow of the pantograph and the contact wire of the catenary occurs, leading to the deterioration of the functional conditions of the two systems. These situations require that the dynamics of the pantograph-catenary are properly modelled and that software used for analysis, design or to support maintenance decisions is not only accurate and efficient but also allows for modelling all details relevant to the train overhead energy collector operation.

In the great majority of cases, high speed trains are operated with two pantographs in constant contact with the catenary. The purpose is to provide the necessary energy required by the electrical engines in order to keep the trainset running at top operational speeds. Nevertheless, the multiple pantograph operation raises problems that do not occur when using a single pantograph. Such problems need to be analysed with further detail and include the influence of the leading pantograph over the contact quality on the rear one. These issues are studied here for a high speed train running at 300 km/h and for different distances between pantographs. Also the influence of the track and environmental conditions is addressed here. For this purpose, the pantographs are mounted on a railway vehicle running on a general track that includes the experimentally measured irregularities. The environmental perturbations considered here are the aerodynamics forces resulting from side winds, collected experimentally in a wind tunnel.

The results presented here show that the front pantograph in the high-speed trains interferes with the performance of the rear one. In fact, the passage of the leading pantograph originates an excitation of the overhead contact line. Then, when the rear pantograph passes on that location, higher contact forces arise, resulting in the degradation of the interaction conditions.

It is also observed that the wind loads have the tendency to raise the pantographs, which increases the contact forces. This contact forces growth promotes the wear of the pantograph collector and of the contact wire. But, conversely, it reduces the tendency for contact loss occurrences that are observed on the rear pantograph.

Regarding the influence of the track irregularities on the pantograph-catenary interaction, it is shown that they have a small effect on the quality of the overhead contact when compared with the other parameters analysed here. This means that the vibrations at the pantograph base, resulting from the track perturbations, are highly damped by the two levels of suspension of the railway vehicles.

The results presented in this work demonstrate that there are several factors inherent to the railway operation that contribute to reduce the quality of the pantograph-catenary interaction, namely by increasing the contact loads and by promoting contact losses. By understanding the consequences of these factors, clear rules can be set to define the limit operating conditions of high-speed trains according to the physical circumstances that the railway vehicles experience in service.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £130 +P&P)