If Rse is decreased step by step fr

If Rse is decreased step by step from its high value, Ia (armature current) increases. Hence, this method increases Ia. On the other hand, as Ia is increased the motor speed N increases. These two possible approaches to control could have been done manually or automatically. Either way, however, results in at least two problems, presuming we do not want to change the design of the armature: