This type of motor acts powered by DC power source. This fact assigns a great limitation in the field of application of this type of motors, since, as we perceive the public electric network that serves our houses, the industries and the commerce operate in alternating current. The technical characteristics of an engine of this type, such as the relative ease with which it is possible to control the speed and high levels of torque at low engine speeds, supports specific applications with electric traction (trains, trolleys, trams) and uses in industrial processes that require these properties, such as rolling mills and drives for mechanical load positioning (automated systems and robots).
A very common use of this type of engine is in a starting engine of vehicles powered by combustion engines where a source of direct current (battery) is available and high torques are required at low speed. DC motors are classified into four groups: DC motors with independent excitation; dc motors with series winding; parallel-winding DC motors and compound winding DC motors.