1 minute read


Direct Current (dc) Generators

An AC generator can be modified to produce direct current (DC) electricity also. The change requires a commutator. A commutator is simply a slip ring that has been cut in half, with both halves insulated from each other. The brushes attached to each half of the commutator are arranged so that at the moment the direction of the current in the coil reverses, they slip from one half of the commutator to the other. The current that flows into the external circuit, therefore, is always traveling in the same direction.



Macaulay, David. The New Way Things Work. Boston: Houghton Mifflin Company, 1998.

McGraw-Hill Encyclopedia of Science & Technology. 6th edition. New York: McGraw-Hill Book Company, 1987, vol. 7, pp 635-37.

David E. Newton


. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Alternating current

—Electric current that flows first in one direction, then in the other; abbreviated AC.


—A part of a generator consisting of an iron core around which is wrapped a wire.


—A split ring that serves to reverses the direction in which an electrical current flows in a generator.

Direct current (DC)

—Electrical current that always flows in the same direction.

Prime mover

—The energy source that drives a generator.

Slip ring

—The device in a generator that provides a connection between the armature and the external circuit.

Additional topics

Science EncyclopediaScience & Philosophy: Gastrula to Glow dischargeGenerator - Principle Of Operation, Alternating Current (ac) Generators, Commercial Generators, Direct Current (dc) Generators