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Benjamin M Ellis

Aircraft Systems and Components

AS 356

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Definition History Why the alternator was created

What is it used for How it works Alternator cutaway Alternator schematic How it works (cont.) Limits Extra information Works cited

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An electric generator that produces alternatingcurrent.

Alternator. (n.d.). The American Heritage Dictionary of the English

Language, Fourth Edition. Retrieved November 21, 2009, fromDictionary.com website:http://dictionary.reference.com/browse/Alternator

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Michael Faraday Was the first to

discover magneticinduction of electriccurrent also known asalternating currentgenerating systems.

Faraday firstdeveloped the rotatingrectangle, which wasthe first successfulconductor that passedcurrents through amagnetic field inopposite directions.

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1882 Two-Phase alternating generating current generators

were built by the British electrician J.E.H. Gordon

1886 The first demonstration of the refined alternator systemdisplayed to the public.

1891

polyphase alternators were created to supply currents of

multiple phases. (To power more than one source at once)Later

Alternators were created to produce alternating-currentsbetween sixteen and one hundred hertz.

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There was a need for producing electricalenergy with a lack of non-mechanical rectifiersof small size, that could operate in high

temperatures and handle vibrations from thegenerator.

Semiconductor diodes that had high currentratings were introduced which made the

Alternator a possibility and advance inelectrical technology.

The alternator produces AC current, howeverreleases DC current in the electric system

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The Electric Alternator is used most commonly intoday's world in civil transportation.

AIRCRAFT!

Boats

Cars

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The biggest advantage the alternator has over the generator isits ability to produce load current in the stator/ stationarywindings and therefore does not have to flow throughbrushes to the load.

Aircraft alternators commonly use the three phase stator. The coils are connected as three windings, which are joined

together to form a Y.

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As the rotor turnsinside the stator, threephases of alternating

current are produced. There are seven pairs

of polls in the rotorand seven coils in

each leg of Y.

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The rotor is made up of two soft iron end pieces with polesthat intermesh onto the shaft. Which are on either side ofan exciter coil.

The ends of the coil are then attached to two slip rings.

The rotor is completely housed and spins on ball or needlebearings.

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Rectifier electrical device that converts alternating current

(AC) to direct current (DC)

Rotor/StatorProduces AC current

Main purpose of the alternator is to produce anexcess amount of DC current to provide a positivecharge to the battery.

Voltage Regulatoris an electric regulator designed to automaticallymaintain a constant voltage level

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The following link is a visual illustration howthe rotor turns inside the stator to producealternating current

http://www.pbs.org/wgbh/amex/edison/sfeature/acdc_insideacgenerator.html

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Most aircraft alternatorsare drivin by the engine.

This can be a majorproblem when the

engine spins thealternator too fast or tooslow which couldproduce to few or tomany volts.

Regulators are usuallyvibrator-type ortransistorized.

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The electric alternator canalso be made completelybrushless which eliminatesthe stator slip rings. Thecurrent needed to producethe magnetic field in therotor is moved to the rotorinductivity.

The alternator in mostcommon General Aviationaircraft is activated byturning on a rocker switch.

By doing this, a positivecharged is then produced tosupply the battery and keepit charged.

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Thomas, J. M. (1991).Michael faraday and the royal institution (the genius of man and place). Bristol, NY: Taylor &Francis.

-American Psychological Association (APA):

Alternator. (n.d.). The American Heritage Dictionary of the English Language, Fourth Edition. Retrieved November21, 2009, from Dictionary.com website: http://dictionary.reference.com/browse/Alternator

Thompson, S.P. (1902). Dynamo-electric machinery, a manual for students of electrotechnics. New York: Collier andSons.

Remer, D.D. (1996).Aircraft systems for pilots . Englewood, CO: Jeppesen.

"AC-DC: Inside the AC Generator ."PBS. 1999-2000. PBS, Web. 23 Nov 2009..