Undulating Wear Mechanism of Overhead Rigid Conductor Line

Abstract

Undulating wear of overhead rigid conductor line causes serious trouble, such as extreme wear of contact line and contact strips of pantograph. In order to analyze the mechanism of wear and propose countermeasures against this problem, we have carried out investigation of wear characteristics of real lines and excitation tests of pantograph. Based on the results of these tests, this paper reports the condition to easily generate undulating wear, discusses the mechanism of wear process and proposes some countermeasures to prevent undulating wear.The unevenness measuring device used in this study consists of two pairs of laser sensors to reduce measurement errors due to the vertical vibration of measurement vehicle. The unevenness of sliding surface of rigid conduction line was measured accurately and continuously with this device. The measured undulating wear was characterized as follows. The sliding surface of conductive rail is roughened with serious arc spots caused by contact loss of pantograph; the maximum amplitude of the unevenness (peak-to-peak) is about 0.4 mm (Fig. 1); the wavelength is about 12 cm, which is equivalent to half the distance between two contact strips of pantograph; and undulating wear tends to occur in the section where trains are in powering at about 45 km/h (Fig. 2) and the deviation of rigid contact line is larger than 50 mm.

Mechanism of Undulating Wear Formation of Overhead Rigid Conductor Line Related to Dynamic Characteristics of Pantographs

“…The wavelengths of the undulating wear at the areas A and B correspond with L/N. Undulating wear at the area A was found in the past investigation (6) . Although undulating wear at the area B could not be observed in the past investigation, the formation of the undulating wear was predicted (6) .…”

“…Undulating wear at the area A was found in the past investigation (6) . Although undulating wear at the area B could not be observed in the past investigation, the formation of the undulating wear was predicted (6) . On the other hand, undulating wear at the area C was also found for first time in this measurement.…”

“…The authors have measured unevenness of the conductor lines several times in the past (4)~ (6) . The configuration of pantograph heads of pantographs used in this commercial line is similar to the one shown in Fig.…”

“…The PSD of the unevenness is obtained by short time Fourier transform (STFT) in spatial domain. In addition, since the PSD of the unevenness often reduces proportionally to 10 -3log n (n: wave number) (6) , the PSD is normalized by multiplying 10 3log n in order to check the distinct undulating wear easily. The vertical axis of the figure of the PSD indicates the wave number of the unevenness defined as a reciprocal number of wavelengths in this paper.…”

“…When the conductor line has unevenness with L/N wavelength which pantograph heads loss contact simultaneously, arcs between the pantograph heads and the conductor lines occur at concave portion of undulating conductor causing extreme undulating wear. Furthermore, it was reported that dynamic characteristics of the pantograph also plays an important role in the formation of the undulating wear (6) .…”