Electric arc power collection system for electric traction vehicles

Abstract

One of many problems in electric traction vehicles is supplying the necessary power to the vehicle. The main difficulty with a conventional overhead system is the maintenance of good contact between the sliding pantograph and the catenary system. As an alternative to the pantograph–catenary system for power collection by contact, there are some methods of power transfer to a moving vehicle without contact: capacitive coupling, electromagnetic-wave transmission, inductive coupling and through an arc plasma. This paper proposes an electric arc power collection system to be used at electric traction vehicles such as tramways and trains. Starting from Nottingham’s equation on the approximation of volt-ampere characteristic of the direct current electric arc, a mathematical model which includes the variation of the electric arc length, depending on the moving electrode rotations speed, is being proposed. Next, the test bench, especially designed for the analysis of power transfer through the electric arc, between a fix and a moving electrode, is presented. Practically, a simulation of an electric traction system running was developed, in which the main dc motor is supplied from a source of continuous variable voltage from a dc generator by means of the electric arc developing between a copper disc and the graphite skate contact, the key element of a tramway pantograph built at a scale of 1:4. A longitudinal argon blow-out has been used to sustain the electric arc. The electric arc characteristics at various arc column lengths, various moving electrode rotations and various argon blowing speeds along the arc column, have been analyzed. Also, from experimental tests, the variation of the rotation velocity of the moving electrode against length of the arc column, has been obtained for different blowing speed of the argon gas. There is a good correlation between experimental data and computing results of electric arc characteristics for different rotation velocity of the moving electrode and different length of the arc column, in stationary conditions.