Commutator in case of DC machine?
Answers
Answer:
Commutator acts as a reversing switch. Its action in motor and generator is as below:
In case of a DC motor, commutator reverses the current (available from a DC source) at the exact instant when the armature coil crosses the magnetic neutral axis. This is necessary to maintain a unidirectional torque. Thus, the commutator converts direct current into alternating current.
In a DC generator, the emf induced in the armature coil is alternating in nature. Accordingly, the current flowing in the armature coil is also alternating current. Commutator reverses this current at the exact instant when the armature coil crosses the magnetic neutral axis. Therefore, the load (which is external to the generator) gets a unidirectional current or direct current.