Determination of Coil Currents in Traction Motors During Commutation

As the largest producer of diesel-electric locomotives in the world, Electro-Motive Division of General Motors Corporation has played a major role in the development of the dc traction motor. An integral part of this development has been the improvement of methods needed to evaluate the performance of proposed traction motor designs. This paper introduces an experimental method, now under development, that enables one to determine the current waveform in an armature coil as it is being commutated. The usefulness of this facility is twofold. First of all, an investigator can use this method as a tool to enable him to understand better the phenomenon of commutation, which has long been a perplexing problem for those working in the area of applied machines. Second, an engineer can use the infornation obtained by this method as an indication of the effects of a given design change on commutation.