Abstract
KEYWORDS – Eddy current brake, track, railway infrastructure, electromagnetic modelling, thermo-mechanical interaction.
ABSTRACT - Eddy Current Brakes (ECB) have been used in a certain amount of high speed railway lines during the last 10 years. Nevertheless, their use is not extended to other lines because the interoperability with some systems of the infrastructure is not accomplished. ECUC project, a European EU-funded project focuses its efforts in proving that Eddy Current Brakes are a highly effective and applicable solution for new high speed trains.
With this purpose, this project has worked in the analysis of documentation as standards (subsets, Technical Specifications for Interoperability, EN standards), and in the study of results of previous measurement campaigns. This analysis has been carried out with the aim of defining the most relevant design parameters of the brake and the main requirements from the point of view of the infrastructure. The results of this analysis made clear that some signalling systems and the infrastructure are affected. From the electromagnetic (EM) interaction point of view, axle counters are the most affected signalling systems, whereas balise readers and track circuits could also malfunction when ECB is present. Regarding thermo-mechanical effects due to the presence of ECB, the increase of the temperature at the rail and the vertical, lateral and longitudinal forces have been studied.
Based on the results of this analysis, the modelling of EM and thermo-mechanical interaction of ECB with the infrastructure is being carried out. EM modelling focuses on the main problems between ECB and axle counters due to the presence of metallic materials and generated magnetic fields. Regarding thermo-mechanical compatibility, the general application of ECB raises rail head temperatures (due to the induced currents by the electromagnetic field) which increase longitudinal forces and introduce extra vertical force. Moreover, this effect can finally lead to lateral or vertical buckling of the rail. Therefore, this task focuses on modelling the heat transfer within the rail and the estimation of longitudinal, vertical and lateral forces.
Apart from the understanding of the interaction between ECB and the infrastructure, some specific design improvements have been proposed for a new generation ECB. These improvements are based on already existing know-how, and rely on the conclusions of the first study which tackle the qualitative relationship between requirements and design parameters.
With the aim of validating the model and testing new generation brakes, during 2014, ECB equipped trains will be tested on the track and in laboratories. The test conditions for these tests will be based on the results of the model and the previous study. Realistic representative worst case conditions will be the inputs for the requirements of the test site, test procedure and test setup. First, laboratory tests will be performed, followed by investigations on the track.
This previous analysis and the first results of the model shown in this paper are the first steps of ECUC project, whose main technical outputs will be technical recommendations defining new requirements for ECB equipped trains.