What is commutation? How can a commutator convert ac voltages on a machines’ armature to dc voltages at its terminals?
Commutation: Commutation is the process a coil undergoes after leaving the magnitude field of one pair of poles and just before entering the magnetic field of the next pair poles. Converting ac voltages on a machines’ armature to dc voltages by commutator : This function is performed by a commutator. The ends of the coil are connected through the commutator to the brushes which lead to the external circuit. An explanation of fig 1 will clarify this process while the coil moves from position 1 to position 2 the brushes remain in contact with the commutator segment and the current direction remain as indicated although the magnitude decreases. At position 2 of fig 1 the voltage induced in the coil is zero, and the current in the external circuit is also zero. At this instant segment A leaves brush 1and makes contact with brush 1. As the coil moves from position 2 to position 3, segment