Incremental and Incremental with Commutation Encoders 

Incremental encoders are used for asynchronous motors requiring no absolute rotor position. They are primarily used for speed control. Incremental encoders generate impulses which correspond to position, angle and

numbers of turns. They contain a disc with defined number of lines on it. The number of lines on the disc determines the resolution capability. The particular position is determined by counting these impulses from a reference point. A reference run is required to determine the absolute position.