GENERAL ENGINEERING Taking the brakes off Dr Daniel Valderas, leader of a project investigating the compatibility of state-of-the-art electromagnetic brakes with high-speed train systems across Europe, reveals some surprising findings from the research Could you outline how you came to work no mechanical contact between the brake and damage. This temperature limit can now on the Eddy CUrrent brake Compatibility track, there is no wear, fine dust, smell or noise be observed from the point of view of ECB (ECUC) project? from its usage. It can be used as both a service performance superimposed on the current and an emergency brake. Catenary power agents that increase rail temperature. In Our department at the Centro de supply is not essential in all ECBs. the case of electromagnetic emissions, the Investigaciones Técnicas de Gipuzkoa (CEIT), standard that probably lies closest to our a non-profit research institute in Spain, has a How has the project used electromagnetic and case study is the CLC TS 50238-3, which wealth of experience in the railway sector and thermal modelling to anticipate the behaviour defines compatibility between rolling stock provides technology to train manufacturers of railway systems? and train detection systems, particularly such as the Constructions and Auxiliary of in regard to axle counters. However, this Railways (CAF) and has coordinated high- Two computer models have been developed standard ignores the usage of ECBs. ECUC profile European Union projects. Together with in ECUC: one thermal, to anticipate the does not intend to directly impact on any major manufacturers such as Knorr-Bremse temperature of the track, and another standard, but can initiate a review by and Deutsche Bahn, we have encountered electromagnetic, to calculate the interference providing insights and recommendations. the need to exploit the full potential of eddy produced by the brake. Both have been current brakes (ECBs) for high-speed trains contrasted with measurements taken in the Have there been any surprising results from throughout Europe. This need led to the launch laboratory and in test runs on a track with an the project? of the ECUC project. intercity 3 (ICE3) train fitted with ECBs. The models provide estimated outputs according to From a thermal point of view, intuition says ECBs have been successfully used on German particular inputs. that maximum speed (300 kilometres per railways in recent years. What lessons have hour) and brake performance will lead to a been learned from the German experience? In the case of temperature, the inputs are train maximum track temperature increase. Yet braking force, numbers of ECBs per train, in reality that it is not always the case. Our It is the German success that makes the speed, number of trains per hour, wind speed modelling and measurements show that technology so promising. After several and ambient temperature. The output is the there are speeds that are more critical for years on specific German railway tracks, temperature increase in the track due to ECB rail heating in combination with maximum future expansion to other countries is operation. In the case of interference, the input ECB performance, such as 120 kilometres being considered. However, a thorough basically refers to the brake current. The output per hour. interoperability study is very important. That is radiated emissions or interference with axle was the rationale of ECUC: to provide starting counters – namely, devices on a railway that From an electromagnetic point of view, the recommendations for this. detect the passing of a train between two points interferences of ECBs at the frequency of on a track. operation of axle counters will probably not How do ECBs differ from traditional be the most important factor to watch. The railway brakes? What regulation of ECBs would you like to see interaction of ECBs and axle counters are to enable further development? realised through the rail, to which both are Basically, an ECB is a large magnet which, very close. It is the change in the properties when it comes into close proximity with the Each country has its own tabulated of the rail, caused by the action of ECBs, that rail, slows down the train. What makes ECBs threshold track temperatures over which could hypothetically make an axle counter fail so special are their ‘green’ features. As there is there is a certain risk of infrastructure in its reading. 82 INTERNATIONAL INNOVATION The future of high-speed trains As the Eddy CUrrent brake Compatibility Project nears completion, its firm recommendations for greener, quieter and more economic braking technology could contribute to increasing the capacity and performance of Europe’s high-speed railway systems IN 1851, THE French physicist Léon Foucault ECBs are currently used in amusement parks electromagnets fed by an external power discovered that a metal conductor moving in on rollercoasters and other rides that need supply, thus the braking force can be finely a strong magnetic field generated circular to change speed abruptly. They are also used controlled by adjusting this field. The faster the magnetic fields, or eddy currents, within on high-speed trains, such as Japanese train travels, the greater the braking force. the conductor. He found that this dissipated bullet trains, and trains on the LGV Est line in the kinetic energy produced as heat. The France and some of the Deutsche Bahn lines Since ECBs exploit magnetic force directly, the phenomenon came to be used in eddy in Germany. braking force is independent of the coefficient current brakes (ECBs) some decades after of friction. This means that they are efficient Foucault died. BENEFITS OF ECBS IN TRAINS regardless of environmental conditions, such ECBs on trains consist of electromagnets in as whether or not there are wet leaves on a linear arrangement, with alternating north- the line, for instance. In contrast to regular and south-pole alignment. A magnetic field contact brake systems, dust pollution, noise operating across the air gap between the and odour are not problems – and as there is rail head and magnets mounted on the truck no mechanical wear of the brakes, they require induces a braking force due to eddy current very little maintenance and are therefore losses. The magnetic field is created using economically friendly. Indeed, compared to contact brakes, ECBs are estimated to be 50 per cent more cost effective over the course of their lifecycle. Gilles Ruaux, Head of Subsystems for Brakes The ECUC team and Air Production at the National Society of French Railways (SNCF), considers that designed a physical setup for testing different eddy current brake systems under real-world conditions with an ICE3 train, at speeds of up to 300 kilometres per hour www.internationalinnovation.com 83 THE EDDY-CURRENT BRAKE ECBs can deliver additional economic has successfully expanded understanding COMPATIBILITY PROJECT benefit by increasing the capacity of the of the interactions between ECBs, the track OBJECTIVE European railway infrastructure, allowing and trackside signalling equipment. The To prove that Eddy Current Brake (ECB) is a highly the more frequent usage of railway researchers have also identified critical effective and applicable solution for increasing the lines. This is because shorter stopping thermomechanical and electromagnetic braking capacity of new high-speed trains. distances make the increase of the train design parameters for ECBs and train flow possible. Additionally, because and trackside compatibility limits, and KEY COLLABORATORS ECBs function independently of adhesion have developed new design, engineering Dr Daniel Valderas; Dra Nere Gil-Negrete, CEIT, Spain between the wheel and track, and can be and operational guidelines for ECBs and Francois Cabillon, Alstom, France powered independently of the catenary trackside signalling equipment. electricity supply, they bring an additional Gilles Ruaux, National Society of French Railways brake force not reachable by conventional A key feature of the project was the design (SNCF), France contact brakes. and implementation of state-of-the-art Dr Gavin Lancaster, Frauscher Sensortechnik, Austria testing facilities. Using the test bench ECB ISSUES of Knorr-Bremse, the foremost ECB Dr Henry Lehmann, Knörr-Bremse, Austria Gilles Ruaux is currently collaborating on a manufacturer, the ECUC team designed Maya Petkova, Network Rail, UK research project focused on the suitability a physical setup for testing different ECB of wider ECB deployment in Europe. systems under real-world conditions with an Oliver Stark; Wilhelm Baldauf; Silvia Eickstäedt, Entitled Eddy CUrrent brake Compatibility ICE3 train, at speeds of up to 300 kilometres Deutsche Bahn, Germany (ECUC), the three-year project is part of per hour. Andrea Demadonna, UNIFE, Belgium the European Commission 7th Framework Programme, and will be completed at the Electromagnetic tests were also conducted FUNDING end of August 2015. ECUC researchers were in the laboratory, using 3D computer This work is funded by The European Union’s Seventh tasked with investigating whether ECBs modelling systems to explore ECB Framework Programme (FP7)-TRANSPORT under the would increase the braking capacity of interaction with wheel sensors and other project Eddy CUrrent brake Compatability (ECUC) with next-generation European high-speed trains, parts of the infrastructure, as well as contract number 314244. and to put forward recommendations for increases in track temperature resulting Consortium: CEIT, Knorr-Bremse, Alstom, SNCF, interoperability in complex railway systems. from their use. The tests covered cases Deutsche Bahn, NRIL, Frauscher, UNIFE where the ECBs were disconnected, and One issue with ECBs is that the intercity at both high and low electromagnetic CONTACT express 3 (ICE3) trainsets used on some frequencies. As a result of these modelling Dr Daniel Valderas European lines have raised questions about systems, the ECUC team determined that ECUC Project Coordinator their electromagnetic compatibility with ECB performance was satisfactory. They also CEIT Pº Mikeletegi 48 Europe’s railway infrastructures.