Work on pantograph / catenary interaction involves the use of a whole range of tools. The DB Systemtechnik pantograph test bench is one such tool, and since being taken into commission in 2001 has been used for a great variety of tasks. The test bench extends the scope within which laboratory trials can be used instead of costly track tests. Test benches are now widely employed for testing new pantograph developments as well as for homologation.
The test bench currently in use at the DB Systemtechnik premises in Munich comprises a solid steel frame mounted with several computer-controlled actuators. The pantograph itself is placed under the steel frame where the actuators then allow a piece of artificial contact wire to move freely in two directions above the pantograph. In this way it is possible to reproduce a broad spectrum of pantograph movements in a controlled manner. The computer-controlled actuators can be programmed to impose specific frequencies and amplitudes on the pantograph whilst measuring the corresponding contact forces. This functionality is, for example, used to verify that measurement pantographs adhere to the measurement standard EN50317. The same functionality is however also used when extracting simulation parameters for pantograph models used in simulations (The relevant standard here is EN50318). When using a multiple mass model, the frequency response of the model is adjusted to correspond to the frequency response of the actual pantograph on the test bench. This produces hi-fidelity simulation results as the results are validated by hands-on testing.
The computer control can also be programmed to reproduce a movement on the pantograph head that has previously been measured on track. In this way it is possible to replay actual measurement runs as many times as necessary in the controlled and reproducible environment of the laboratory – eliminating variable external influences on results. Additional measurements on the pantograph which may be difficult to carry out on the track may in this way be comfortably carried out without the need for complicated rooftop solutions. The ability to replay track data also permits easier modification and testing of new pantograph configurations and can also be used to perform comparisons between pantographs to determine which pantograph is most suitable for a specific track. Though the method is limited in accuracy due to different pantographs producing different dynamic interactions with a specific catenary, comparisons obtained can be a source of useful data for qualitative comparison: i.e. “better” or “worse” comparisons rather than actual 1:1 reproductions.
Recent and current projects have increasingly focused on the pantograph test bench as a means to reduce the cost of introduction and homologation of new pantographs. In a European project named EUROPAC (2005-2007, 6th framework programme), the pantograph test bench was used to not only to verify the accuracy of the overhead line contact force measurement system employed but also to create pantograph models that were then used in computer simulations. In an on-going project, PantoTRAIN (2009-2012, 7th framework programme), the test bench will be used for pantograph / catenary interaction investigations to determine to what extent such tests can be used to simplify the homologation processes currently in place. The goal of the PantoTRAIN project is to reduce overall homologation costs through intelligent use of additional tools (as compared to on-track tests) such as pantograph test benches, computer simulations and wind tunnels.
Undoubtedly, test benches together with other tools will simplify the homologation process, the only question remaining, is to what extent.
