Development of Observation System for the Vibration of a Wire-Pantograph System with a Super-Anamorphic-Lens

Katsushi MANABE

Manager, Current Collection Lab. Fundamental Research Department


Engineer, Contact Line Structure Group, Power Supply Technology Development Department

Mitsuhiro AOKI

Assistant Official, Central Japan Railway Company

The vibration of overhead wire is one of the most important performances for a wire-pantograph system. It is said that the overhead wire displaces with wavelengths as long as several tens of m in the longitudinal direction and amplitudes as small as 01.m in the normal direction. We successfully developed a super-anamorphic-lens with a focal length ratio of 76:1 that permits simultaneous televiewing of its vibration over several spans.


Until now, we have measured the vibration of overhead wire with a displacement-meter, an accelerometer or a strain-gauge, but in this way we can measure the behavior of the vibration only at several places and cannot make clear the whole behavior of it. It is said that the overhead wire displaces with a long wavelength of several tens of m in the longitudinal direction and a small amplitude of 0.1m in the normal direction. Because of the difference of the amplitude from the wavelength, we cannot gain a clear image of the wire deformation by an ordinary lens. In order to get a clear image of a vibrating wire, we developed a Super-anamorphic-lens with a focal length ratio of 76:1. Fig.1 shows a concept of observation system with this lens.

2.Characteristics of a Super-anamorphic-lens

Table 1 shows the characteristics of the Super-anamorphic-lens. This observation system uses 1/3 inch CCD camera that has the smallest size of all mass-produced ones. If a wire is at a distance of 50m distant from this lens, for example, we can get an image of the wire covering a length of 52.2m and a height of 514mm. The magnification ratio of height to length of the wire appearing on the monitor is 80:1. Fig.4 illustrates an image of a wire-pantograph system over one span (50m), which enables the vibrational behavior of the wire to be observed distinctly. Fig.5 illustrates an image of an overlap section, which shows the pantograph motion and the wire waves in the section clearly.


It is clear that Fig.4 and Fig.5 show the deformation of overhead wire with fairly high accuracy. We intend to develop an analytic way of finding the displacement, vertical velocity, inclination, curvature etc. of a wire.