Development and Limits of Elecric Traction Drive.

Given the progress of power semi-conductors, and thus of converters, an examination is made of what limits will be encountered by the determining factors of traction and what conditions have to be satisfied by the converters to give the best results in terms of weight, safety and simplicity. An examination is made of the limits of wheel/rail adhesion. To date, there emerges from an examination of the units in service or in the design stage, that the values of adhesion are generally utilized only up to 70-90 k. p. h. , especially on gradient lines. An analysis is then made of the advantages and defects of three-phase motors as compared with d. c. motors from the point of view of the lower production of harmonics and the elasticity of the characteristics and simplicity of construction, in terms of trustworthiness. It is concluded that the limit capacities can already be reached now and an increase of the elasticity of the motors for the higher speeds is also possible; the development of the different solutions is substantially directed towards the reduction in weight and the simplification of the operating elements.