The armature circuit may be fed from either an amplifier or a contactor. The direction and speed of armature rotation depend on the value and polarity of the armature voltage.

Then the model is applied to simulate the direct start-up process, the reduced voltage starting process and the starting process with series resistance in the armature circuit.

The field circuit and the armature circuit can be interconnected in various ways to provide a wide variety of performance characteristics - an outstanding advantage of DC machines.