AC motors can also include variable-frequency drives to control the motors speed and torque while DC motors are available in self-excited and separately excited-type models. The series machine works as a self-excited generator and the field connection reverses so that the field assist the residual magnetism. Types Of Motors Classification Of Ac Dc Special Motors Electric Motor Electrical Circuit Diagram Electricity Here the speed control is similar to the speed con trol of separately excited DC. . There are four main types of DC motor all of which are used for different applications. This article discusses an overview of the series motor and the main function of this motor is to convert electrical. Separately Excited DC Generator. GE Electric Motor Parts. Why DC series motor should not be started without load. It is a normal DC motor with its field winding separately excited. A DC motors speed and torque c...