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In this paper, the influence of the continuous DC arc whose current values are from 100 A to 400 A on the contact strip of the railway pantograph is experimentally investigated. The arc between the contact wire (trolley line) and the contact strip (pantograph) causes some problems on the system such as a trolley breaking and the investigation of the phenomena is seriously desired in the DC railway system. The comparison of the surface condision of the contact strips which is exposed to the arc, the ingredients analysis by the electron probe micro anarysis (EPMA) and the hardness measurement based on the micro-Vickers test were performed. Figure 1 shows the wear of the contact stip arounce the arc trace. The arc current value was 200 A and the the current was fed till the contact wire was broken by the arc. The left figure (a) is the positive arc in which the currrent flows from the contact wire to the contact strip while the right figure (b) is the negative arce in which the current flows from the strip to the wire, respectively. The surface of the strip is seriously damaged by the negative arc which causes the 1 mm depth hole with 10 mm diameter while the surface of the strip remains flat by the positive arc. Figure 2 shows the results of the ingredient analysis by the EPMA. The weight percentage of copper (Cu), carbon (C) and lead (Pb) dependence on the depth of the material is shown in this figure. The strip was exposed to the 100 A arc for 2 second. By the positive arc, the surface of the strip was not physically damaged by appearance as shown in Fig. 1(a). Through the EPMA tests, it was shown that the copper in the contact strip was decreased around the arc trace while the carbon was not influence by the arc. As the melting point and the boiling point of the copper or lead are lower than those of the carbon, the carbon and the lead are thought to be influenced by the arc. The two dimensional ingredients’ distributions in the material (EPMA mapping results) are also shown in the paper.

Influence of the Arc between the Contact Wire and the Pantograph on the Material of the Contact Strip