Function of Commutator in DC Machines

Commutator in DC Motor

The commutator in case of a DC motor, it reverses the flow of current which is accessible from a DC source at the exact time while the armatures coil crosses the magnetic unbiased axis. This is essential to keep a uni-directional torque. Therefore, the commutator will change the direct current (DC) into alternating current (AC).
Commutator in DC Generator

The commutator in case of a DC generator, the induced e.m.f within the armature coil will change in nature. Consequently, the flow of current in the armature coil will also be changed. This current will be reversed by the commutator at the exact time while the armatures coil crosses the magnetic unbiased axis. So, the load which is external to the generator will get a uni-directional current otherwise DC (direct current).