commutator


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commutator,

device used in an electric generatorgenerator,
in electricity, machine used to change mechanical energy into electrical energy. It operates on the principle of electromagnetic induction, discovered (1831) by Michael Faraday.
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 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 motorsmotor, electric,
machine that converts electrical energy into mechanical energy. When an electric current is passed through a wire loop that is in a magnetic field, the loop will rotate and the rotating motion is transmitted to a shaft, providing useful mechanical work.
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 to switch currents in order to maintain magnetic polarities necessary to keep the shafts of the motors turning.

Commutator

 

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.

REFERENCES

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

V. V. BOGOMAZOV

commutator

[′käm·yə‚tād·ər]
(electromagnetism)
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.
(mathematics)
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.

commutator

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
References in periodicals archive ?
We shall represent an expression, describing cutting force when turning the intermittent commutator surface, as:
The vertices of the facet corresponding to a commutator [gamma] are the brick vectors of the pseudoline arrangements supported by [N.
In Section 3, we present some preliminary results for a commutator associated with a one-dimensional model.
Collector's thermal coupling with armature through armature winding sections contacts with commutator segments lugs.
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.
OTCBB: TCPS), today announced a new patent filing of twenty claims for protection of its "Linear Commuting Amplifier" design, a key circuit implementation that enables integrating a commutator (to translate signals in frequency) with its high-performance delta-sigma Analog-to-Digital (A/D) converter to form a direct Radio Frequency-to-Digital (RF/D(TM)) converter as already recited in TechnoConcepts' Delta-Sigma Receiver patent.
Tenders are invited for Armature Wound With Commutator With Slot Insulation
OTCBB:LMGR), developer of new applications in optical and light technologies employing the use of sound waves to direct light, today announced the scheduled launch of its new single-to-multi-mode Acousto-Optic Commutator fiber optic switch (product identification AOC1-s/m).
The optical lines employing LMGR's proprietary commutator can carry 10 Gigabytes of information per second, in comparison to 50 Kbits over phone lines -- i.
Tenders are invited for Commutator Grinding Stone, Medium Grade With Wooden Handle For Grinding Commutator Of Traction Motors / Traction Generators Of Diesel Electric Locos To Rdso Drg.
The Company has recently applied for two patents: most recently for its radically new Fiber Optic Information Compressor design; and earlier this year for its Fiber-Optical Line Commutator, an invention that does not have any mechanical parts and which uses an electronically and computer controlled acousto-optical deflector set that can randomly connect the channels from the array to the single fiber-optical line, resulting in extremely fast switching times -- of not more than a few microseconds.