The gear motors dc have great advantages, among which is its ability to be stored in a relatively simple way. This, together with a number of peculiar features of the motors of dc, and of applications of electrolytic processes, electric traction, among others, allow that there are various facilities that work based on the continuous current.
The generators of dc are the same machines that transform the mechanical energy into electrical one. There is not real difference between a generator and a motor except for the direction of power flow. The generators are classified according to the way in which it provides the flow field, and these are of independent excitation, shunt, series, excitation compound cumulative compound differential, and in addition differ of their characteristics terminals (voltage, current) and therefore in the type of use.