These are generators in which the field winding is excited by the output of the generator itself. As described before there are three types of self excited dc generators – they are is shown in figure (b), in which the field winding is wired parallel to armature winding so that the voltage across both are same. The field winding has high resistance and more number of turns so that only a part of armature current passes through field winding and the rest passes through load.
is shown below in fig (a) – in which the armature winding is connected in series with the field winding so that the field current flows through the load as well as the field winding.Field winding is a low resistance,thick wire of few turns. Series generators are also rarely used!