commutator, device used in an electric generator to convert the alternating current produced in the generator into direct current before the current is sent into an external circuit; it is basically a rotary switching device synchronized with the frequency of the alternating current. Commutators are also used in electric motors to switch currents in order to maintain magnetic polarities necessary to keep the shafts of the motors turning.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.