Contribution to the Study of Commutation in Small Uncompensated Universal Motors

A method, is, given to: study the current reversals in a small. motor. The commutation process is shown to be widely different of what it is in a big motor ; as an example, the voltage drop across the sliding contact is small as compared to the inductive voltages aa an other example, there exist ripples of the input current which are at commutation frequency, and which play an important role in the conmutation process. The influence of the brush shift is discussed. An experimental verification is given.