Commutator

Commutator is used in DC Machines. In DC Generators it facilitates the collection of current from the armature conductors to an external c
ircuit. Whereas in DC Motors it facilitates for sending the line current into the armature conductors

Commutator as Mechanical Rectifier

The commutator also functions as a mechanical rectifier as it converts the alternating current in the armature to the direct current. The current flowing through armature conductors of a DC machine is an alternating current. Commutator converts this bidirectional alternating flow of current into unidirectional direct current to the external circuit.

Structure of a commutator

The commutator is cylindrical in shape which is built by wedge shaped high conductivity copper segments insulated from each other by thin layers of mica. Each Armature conductor is connected to each segment with the help of a copper lug. The number of segments in the armature coils is equal to the number of commentator segments. Carbon brushes are used to collect the current from (in DC generator) or send to (in DC motor) the commutator which slide on the commutator segments.