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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.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in electrical machinery, a mechanical frequency converter that is attached to the rotor of a machine. A commutator consists of a series of trapezoidal copper segments that are insulated from each other and from the body of the rotor. Each segment is connected to one or more turns of the armature winding. The armature winding is connected to an outside power source by carbon contact brushes. When the armature rotates, the brushes touch each of the commutator segments in turn.

The most common type of commutator is the cylindrical type, with brushes contacting the outer surface. Disk commutators, whose work (contact) surface is perpendicular to the axis of rotation of the rotor, are less frequently used. The commutator segments in low-powered machines (up to 10 kilowatts [kW]) are pressed into plastics; in machines with power ratings of 15–25 kW or more and a speed of rotation of 3,000 rpm or higher, the segments are fastened by steel tread rings. In large electric machines double or triple commutators are sometimes used to reduce mechanical stresses. The disadvantages of commutators are high consumption of electrical-grade copper, sparking, and wear caused by brush friction.


Petrov, G. N. Elektricheskie mashiny, 2nd ed., part 3. Moscow, 1968.
Vazhnov, A. I. Elektricheskie mashiny. Leningrad, 1969.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


That part of a direct-current motor or generator which serves the dual function, in combination with brushes, of providing an electrical connection between the rotating armature winding and the stationary terminals, and of permitting reversal of the current in the armature windings.
The commutator of a and b is the element c of a group such that bac = ab.
(quantum mechanics)
The commutator of a and b is [a,b ] = ab-ba.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. a device used to reverse the direction of flow of an electric current
2. the segmented metal cylinder or disc mounted on the armature shaft of an electric motor, generator, etc., used to make electrical contact with the rotating coils and ensure unidirectional current flow
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Zhang, "Boundedness of a class of super singular integral operators and the associated commutators," Science China Mathematics, vol.
Green concedes that the recent extension of brushless d-c motors into higher horsepower ranges also eliminates brush and commutator deterioration in conventional d-c motors, but adds that brushless d-c units still have open frames that may draw in dust.
In this paper, we prepare to study the boundedness for commutators generated by bilinear [theta]-type Calderon-Zygmund operators and RBMO([mu]) functions on nonhomogeneous metric measure spaces.
Janson, "Mean oscillation and commutators of singular integral operators," Arkivfor Matematik, vol.
In Section 3, Theorems 12 and 13 show the local higher integrability of commutators of Calderoon-Zygmund singular integral operators on differential forms.
Generalizing from groups we described H' in terms of Hopf algebraic commutators [6].
2,170,389: Apparatus for use in repairing commutators. Patent granted to Charles A.
2 December 2011 - CRISIL on Friday gave BBB ratings with a "stable" outlook to the INR77m (USD1.5m/EUR1.1m) cash credit and INR53m proposed long-term bank loan facility of Indian electrical equipment manufacturer Sahney Commutators Pvt Ltd.
For maximum uptime, three-phase AC drive, lift and steering motors are maintenance-free without carbon brushes, brush springs or commutators. Jungheinrich, 877-543-6757,
A network N is a set of n horizontal lines (called levels), together with m vertical segments (called commutators) joining two consecutive horizontal lines, such that no two commutators have a common endpoint--see Figure 1 (left).
The topics include large transitive groups with many elements having fixed points, threads through group theory, a p-group with no normal large abelian subgroup, commutators with wreath products, problems in character theory, lifting theorems and applications to group algebras, and character degrees of normally monomial maximal class 5-groups.