What is a Commutator? All Questions › Category: Electrical Machines › What is a Commutator? 0 Vote Up Vote Down Akash Tiwari asked 4 years ago 2 Answers 0 Vote Up Vote Down Akash Tiwari answered 4 years ago The device which converts the alternating induced emf of a generator to the DC emf is called Commutator. In the case of the motor, it produces unidirectional torque. 0 Vote Up Vote Down Chetan answered 4 years ago Commutator converts ac supply into DC supply in case of motor. In case of generator, it converts dc supply into ac supply.