Transition Structures between Rigid Conductor Line and Catenary Overhead Contact Line

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1 Transition Structures between Rigid Conductor Line and Catenary Overhead Contact Line T.Kobayashi 1,M.Shimizu 1,A.Oya 2 1 Railway Technical Research Institute, Tokyo, Japan; 2 Former Railway Technical Research Institute, Tokyo, Japan Abstract In applying the rigid conductor line to the narrow tunnel section, the transition structure between overhead catenary system and rigid conductor line is needed at a tunnel entrance/exit. However, since the present transition structure is long and complicated, many support points are required, it has caused the rise of construction cost. Therefore, we developed the simplified new structures about the transition structure. As a result of the running test, it is assumable that the new transition structures are applicable to practical use up to 13km/h. 1 Introduction In the narrow tunnel section, since there is no clearance on the head, special catenary overhead contact line systems, such as feeder messenger type, have been installed. However, these systems are considered as a weak point part of the facility in view of maintenance or current collection characteristics. As the rigid conductor lines adopting in subway may not have the breaking of wire by wear, the maintainability is superior to overhead catenary system. In applying the rigid conductor line in those tunnels, the transition structure between overhead catenary system and rigid conductor line is needed at tunnel entrance/exit, the present transition structure tends to cause contact loss and vibration which causes fatigue of the overhead contact line. Moreover, the transition structure is complicated and needs many support points. Therefore, we developed the new structures which reduced the number of support points by shortening the transition structure. 2 The conventional transition structures Fig. 1 shows the transition structure of subway. The section of tunnel entrance/exit is large on the assumption that adopts the rigid conductor line, therefore it is possible to construct the transition structure inside the tunnel and reduce the number of support points outside the tunnel entrance/exit for the transition section. The structural length of transition structure is required about 5m. The overhead catenary system in transition section does not have the messenger wire and the contact wire is direct suspension from the ceiling of tunnel in many cases, thus, the quality of current collection at the transition section is inferior. Fig. 2 shows the transition structure for the narrow tunnel section. Since the section of tunnel entrance/exit is small, it is necessary to construct the transition structure outside the tunnel. Although the structural length of transition structure is required about 3m and the length is shorter than that of subway, the transition structure is complicated and has caused the rise of construction cost, because many support points at the outside of the tunnel entrance/exit are needed.

2 3m 2m 12.5m 5m Fig.1 Transition structure of subway 2m 35m Fig.2 Transition structure of in the narrow tunnel section 3 The new transition structure 3.1 Stress-relaxation mechanism In shortening the transition section between rigid conductor line and overhead catenary system, the generation of contact loss and the increase of bending stress of contact wire are expected by the rapid height change of the pantograph at a connection point. Accordingly, to transfer the smooth of pantograph at the terminal area, the structure has metallic parts (stress-relaxation mechanism) for the stress relaxation of contact wire by suppressing the sharp bend of it. Fig. 3 shows the structure for stress-relaxation mechanism. The material of stress-relaxation mechanism is same aluminum alloy as a rigid conductor. We developed two types of transition structures with the stress-relaxation mechanism. 25 Fig.3 Structure for stress-relaxation mechanism 3.2 The transition structure of united type Fig. 4 shows the transition structure of united type. Since the contact wire of rigid conductor line uses that of catenary, it does not need terminals. Therefore, it is possible to reduce the number of support points outside the tunnel entrance/exit substantially. This is applicable to tunnels to about 2m without the connection structure (expansion joint) for corresponding to the

3 thermal expansion and contraction of a rigid conductor line inside tunnel. About the vertical interval of contact wires between the overhead catenary system and the rigid conductor, in consideration of the uplift at the time of pantograph passage, overhead catenary system may become low 2-3mm rather than the rigid conductor line section in initial height. 3.3 The transition structure of divided type Fig. 5 shows the transition structure of divided type. This is the structure which attaches the stress-relaxation mechanism and a short rigid conductor line to the terminus part of the contact wire of catenary system. Then the catenary system is anchored to the wall of tunnel entrance and constitutes an overlap with the rigid conductor line. Therefore, this structure can reduce the number of support points outside of the tunnel entrance/exit and it is also possible to shorten the transition section to about 1m. Application to the tunnel of 2m or more which needs expansion joint can be considered. About the vertical interval of contact wires between the overhead catenary system and the rigid conductor, like the transition structure of united type, overhead catenary system may become lower 2-3mm than the rigid conductor line section in initial height. 2m Stress-relaxation mechanism Rigid conductor line Catenary overhead contact line section Rigid conductor line section Fig.4 Structure of united type 2m Stress-relaxation mechanism and Rigid conductor line Rigid conductor line Catenary overhead contact line section Termination Rigid conductor line section Fig.5 Structure of divided type

4 4 Running test 4.1 Test Condition Using the equipment by which the run experiment up to 2 km/h can be performed with the use of the overhead contact line and pantograph of full size, the running test was carried out on two transition structures. Table.1 shows measurement items and criterion values. Figs. 6 and 7 show the measurement result of the initial height of overhead contact line. The vertical interval of contact wire of both types set to about 2-3mm, the running test was carried out. Table.1 Measurement items and criterion values Measurement item Criterion value Contact wire uplift 3mm Maximum contact-loss time Distortion (contact wire) Distortion (stress-relaxation mechanism) 2ms 5μ 16μ Fig.6 Overhead contact line height of united type Fig.7 Overhead contact line height of divided type

5 4.2 Test result (a)contact wire uplift Fig. 8 shows the relation between the contact wire uplift and running speed. Since the contact wire uplifts are 3mm or less up to 16 km/h for both types, it has shifted smoothly satisfactory. Contact wire uplift(mm) Fig.8 The relation between the contact wire uplift and main speed (b) Contact-loss Fig. 9 shows the relation between the maximum contact-loss time and running speed. Since the maximum contact-loss times are 1ms or less up to 13 km/h for both types, namely less than 2ms that is the criterion value [1] used for the quality assessment of overhead contact line, no problem will be raised. 5 The maximum contact-loss continuation time(ms) Fig9.The maximum contact-loss continuation time (c) Strain Fig. 1 shows the measurement position of strain. Figs. 11 and 12 show the relation between strain generated in the contact wire and running speed. At the terminus point, contact wire is united with the stress-relaxation mechanism. Then, the neutral axis in bending moves to the upside, therefore the strain of contact wire at the undersurface may be large than that at the upper surface. Therefore, the data measured at the upper surface is necessary to convert into

6 strain generated at the undersurface. In adding loads in the position of (1) to (4) of Fig. 13, strain generated in the upper surface and undersurface of the terminus contact wire was measured. Fig. 14 shows the ratio of strain (undersurface / upper surface). In pushing up directly under strain measurement position, one a maximum of 4 times the value of this was measured. Therefore, using 4 times as a conversion factor, the relation between strain generated in the contact wire of terminus part and running speed is shown in Fig. 15. Since strains are 5μ or less up to 13 km/h for both types, namely less than 5μ which is the criterion value [1], no problem will be raised. Contact wire (The tip) Structure for stress-relaxation mechanism Contact wire (The terminus) Fig1.Measured points Dynamic distortion(μ ) Fig11.Strain of contact wire (The tip) Dynamic distortion(μ) Fig12.Strain of contact wire (The terminus) Position(1) Position(2) Position(3) Strain (upper surface) Position(4) Strain(undersurface) Fig13.Measured points

7 5 5 The ratio of distortion (undersurface / upper surface) Dynamic distortion(μ ) (1) (2) (3) (4) Position Fig14. The ratio of strain (Undersurface / upper surface) Fig15.Strain of contact wire (The terminus, after conversion) Fig. 16 shows the relation between strain generated in the stress-relaxation mechanism member and running speed. Since strains are 4μ or less up to 16 km/h for both types, namely less than 16μ, fatigue limit of member, no problem will be raised. Dynamic distortion(μ ) Fig.16 Strain of structure for stress-relaxation mechanism 5 Conclusion We developed two simplified new structures about the transition structure between rigid conductor line and overhead catenary system. As a result of the running test to 16 km/h can be performed with the use of the overhead contact line and pantograph of full size, it is assumable that the new transition structures are applicable to practical use up to 13km/h. References [1]RTRI, Description of Overhead Contact Line and Pantograph, Tokyo: Kenyusya, pp92-94, (in Japanese)

Estimation of the characteristic of contact line uplift and strain in the neighborhood of a tunnel inlet by computer simulation

Computers in Railways XIII 147 Estimation of the characteristic of contact line uplift and strain in the neighborhood of a tunnel inlet by computer simulation Y. Sugama1, K. Shimizu1 & S. Amari 1 Railway