Analyses of Contact Force Fluctuation between Catenary and Pantograph.

Abstract

One of the most important subjects of overhead contact line and pantograph system is to reduce the contact loss of pantograph in high-speed operation. In this research, the relation between the wave motion of contact wire and the contact force fluctuation of pantograph is studied; the contact force fluctuation in a hanger span cycle is analyzed; and methods to reduce the contact force fluctuation are proposed. It is shown that the contact force fluctuation of pantograph in high-speed operation is mainly caused by the incident wave of contact wire that is generated by the unevenness of contact wire and is reflected at hangers. This influence becomes extremely large when the train speed is close to the wave velocity of contact wire. Increasing the wave velocity of contact wire or decreasing the reflection factor of wave motion at hangers is expected to effectively reduce the contact force fluctuation.

Installation Guidelines for Shinkansen High Speed Overhead Contact Lines

“…The contact force fluctuation expressed in (2) is for cases where the overhead contact line is assumed as an infinite string model, but real behavior is very complex because the wave motion reflects at each hanger and support point [2]. Therefore, the degree of influence of installation errors may differ depending on location.…”

“…As for the aerodynamic upward force value, 50 N was applied at 300 km/h for pantograph A as the standard value for current commercial vehicles, and 35 N at 300 km/h for pantograph B [11], furthermore, it was assumed that the aerodynamic upward force increases in proportion to the square of the speed. In addition, it was supposed that the flow speed in tunnel sections is 1.2 times that of open sections, therefore the aerodynamic upward force coefficient in tunnel sections is 1.2 2 times that of open sections. Although the number of pantographs on a train set is assumed to be two in case of pantograph A, and one in the case of pantograph B, current collection performance was evaluated for the 1st pantograph, since the target of T T T T T T T T Table able able able able 2 2 6.3 Relationship between items used for evaluation of 6.3 Relationship between items used for evaluation of 6.3 Relationship between items used for evaluation of 6.3 Relationship between items used for evaluation of 6.3 Relationship between items used for evaluation of current collection performance and installation error current collection performance and installation error current collection performance and installation error current collection performance and installation error current collection performance and installation error indices indices indices indices indices…”

“…Contact force fluctuation factors have been reported as follows; ① periodic motion of the pantograph during support point intervals (span) [1], ② periodic motion of the pantograph in hanger spans [2], ③ unevenness of the overhead contact line (change in contact wire height) [3]. The mechanisms of the first and second factors are almost clear, and improvement methods for Shinkansen high speed operations with respect to these factors have been presented in previous studies.…”

“…Converting (1) the origin at the pantograph point and using boundary conditions at that point, the contact force fluctuation of the pantograph is expressed by (2) [3] where i is imaginary unit, Z t , Z p are the mechanical impedances of the overhead contact line and the pantograph respectively.…”

“…Figure 2 shows the relationship between estimated unevenness values on a section of Shinkansen line and the contact loss ratio of pantographs running in this section [3]. The estimated unevenness value is expressed by the standard deviation of the contact force fluctuation derived from (2), in other words, it expresses the degree of the unevenness of the overhead contact line. Calculations were carried out where v=55.6m/s (200 km/h) with the parameters of the pantograph running in this section as the evaluation conditions.…”