A new test bench for examinations of the pantograph-catenary interaction

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1 A new test bench for examinations of the pantograph-catenary interaction Authors: Johann Deml, Dr.-Ing. Wilhelm Baldauf Deutsche Bahn AG, Research and Technology Centre (FTZ), Munich Summary For reaching a high velocity it is necessary for a train or a formation of trains to have a secure electric power supply without interrupts. The Research and Technology centre (FTZ) of the DB AG and especially the department FTZ 72 is responsible for the security of energy transmission between the contact line and the train. To achieve a high contact quality for all operation conditions, the pantograph has to be adjusted and optimised very well. In former times, the adjustment was mainly done by expensive line tests. Today efficient simulation tools and the high dynamic pantograph test bench (see figure 1) can be used for the optimisation at a very early state of the design and development process. The number of line tests can be reduced significantly. With the pantograph test bench static and dynamic examinations to the pantograph and contact force measurement system can be realized with high quality by the valid rules of DIN- VDI, EN, UIC and IEC. Figure 1: Pantograph test bench

2 Functional demands The old, single-axle, electro-dynamic test-bench was the basis for the functional realization of the new pantograph test bench. Further data was achieved by line tests and geometric overhead contact line data. Test methods as well as relevant test specifications were taken into account for the profile of the pantograph test bench. By using the contact line system you get two significant movements: On the one hand a horizontal movement, which is caused by the stagger of the overhead line. On the other hand a vertical movement, which consists on high and low frequency oscillation. The high frequency oscillation part is generated by droppers, stitch wires and mounting tolerances. In comparison with this the part of low frequency movement is caused by slow changes of contact wire height and assembly toleration. A further force effecting the pantograph is the aerodynamic resistance, which is caused by the speed. This force is necessary to conduct realistic experiments and acts on the pantograph contact strip by using a construction of ropes and weights. Functional realization A first construction study resulted in the conception and the geometric measurement. Therefore pantographs with three and four isolators, not exceeding the maximum geometric measure of 1650mm x 1450mm, can be installed in the test bench. To simulate the interaction between the overhead contact line and the pantograph, the test bench needs three separate axes (see figure 2). A portal, which can be moved in vertical direction over a wide range (1.5 meters), simulates slow changes of the contact wire height. A sledge, mounted on the portal, moves in horizontal direction and models the stagger. A hydraulic actuator with a very high dynamic working range in vertical direction is placed on the horizontal sledge. A mass-spring-damper-system, located between the hydraulic actuator and the contact strips, models the catenary system in a very simple way. Figure 2: Principle figure of the pantograph test bench

3 In combination with special stimulation signals for each axis (see figure 3), it is possible to simulate the dynamical interaction between pantograph and overhead line system in a very realistic way. The stimulation signals can be deviated from real line test data or numerical simulations. Figure 3: Required stimulation signals for the pantograph test bench to simulate dynamic interaction Technical Description The axes of the new pantograph test bench have the following realised significant data: Axis Maximal range (mm) Maximal velocity (mm/s) Maximal working frequency (Hz) Portal (low frequency vertical axis) Stagger (horizontal axis) Hydraulic actuator (high frequency vertical axis) Testing methods and possibilities The testing methods, which are realised with the three-axes pantograph test bench, can be classified into four groups. 1) Identification of the pantograph s static parameters

4 - create a graph from the pantograph s differential of horizontal direction over the pantograph s working range measure - measure the raising and the lowering time - measure at the pantograph s kinematics - create a graph about contact force difference and cross wind sensitivity in dependence of the aerodynamical force over the working range 2) Generating a graph about the dynamic attributes from the pantograph Finput ( j ) - calculate the apparent mass graph S( j ) a measured s input ( j ) - calculate the disturbance transfer function f Fmeasured - simulate line tests and calculate the standard force variation (see figure 4) Figure 4: Measured contact force in a simulated line test 3) Calibration of the contact force measurement systems - calculate the pantograph s transfer function f (j ) F F measured input (see figure 5) - control the pantograph and calibrate the measurement system before starting a measurement sequence to get definite and reproduceable measurement results

5 Figure 5: Transfer function of a contact force measurement system 4) Derivation and validation of simulation models Results of measurement methods The movements of the pantograph are illustrated at the test bench as well as the resulting contact force shows a very good compliance with the original railway data. The standard variation of the contact force is comparable to the results of the railway line tests and can used for judging the dynamic quality. The effect of each optimisation step can be determined fast and reproducible for various types of overhead contact lines. The portal is also used for measurements of pantograph differential of horizontal direction. A device to induce horizontal power allows the consideration of aerodynamical force on the pantograph. It is therefore possible to achieve the differential contact force of working range characterization of pantographs. Final observations The Research and Technology centre of the DB AG works for one year with the new dynamic pantograph test bench. The realistic simulations, we have got with the test bench, contribute to understand the essential of the pantograph-catenary interaction. The test bench is a very useful tool for the development and optimisation of new, innovative pantographs and will contribute to reduce the number of expensive line tests.