变压器基本知识英文.docx

变压器基本知识英文.docx

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变压器基本知识英文

CONTENTS

SectionOneBasicKnowledgeoftransformer

SectionTwoBasicWorkPrincipleofTransformer

SectionThreeOperationofTransformerinParallel

SectionFourOperationandMaintenanceofTransformer

SectionFiveAbnormalOperationandRemediesofTransformer

SectionSixOperationandMaintenanceofLoadTapSwitch

SectionOneBasicKnowledgeofTransformer

I.UseofTransformer

Thetransformerisastaticelectricdevicewhichcantransformalternativevoltageandcurrenttotransferelectricpowerinsamefrequencybetweentwoormorewindingsbymeansofelectromagneticinduction.

Thetransformerhasalotofuses.Therearevariouskindsoftransformerswidelyusedinalldepartmentsofnationaleconomy.Inviewoftheanglefromtheelectricpowersystem,anelectricpowernetworkconnectsmanypowerplantsandusersandtheelectricenergygeneratedfromtheelectricpowernetworkshallbealwayssenttouserareasbytransmissioninlongdistance.Incasetheelectricpowertobetransferredisconstant,thehigherthetransferredvoltage,thelessthecurrenttobeneededbecausethevoltagedropisindirectproportionwiththecurrentandthelossofelectricenergyisindirectproportionwiththesquareofthecurrent.Thereforeitcanlargelyreducethevoltagedropandenergylossofthetransmissionlinesifhighertransferredvoltageisadopted.Atpresentitisdifficulttechnicallytomakethegeneratorwithhighervoltage,alternatively,thestep-uptransformerisusedtoriseupthevoltageattheterminalofthegeneratorbeforetheelectricpowerissent.Thelongerthetransmissiondistance,thelargerthetransferredpowerandthehighertherequirementofvolumeandvoltagelevelsofthetransformer.Astherearealotoflevelsofvoltageexistedinthepowernetwork,itshouldhavetransformerswithdifferentsizesofvoltagetomakeconnection.

Ontheotherhand,whenelectricenergyistransferredtothereceivingterminalitshouldhavethestep-downtransformertoreducethehighvoltageonthetransmissionlinestothevoltageofthepowerdistributionsystem,thenreducethevoltagetothatrequiredbyallelectricequipmentsthroughthedistributiontransformer.

Itcanbeseenthepositionofthetransformerintheelectricpowersystemisvitalimportant.Notonlyitrequiresmuchtransformers,normallythetotalinstallationcapacityoftransformersare8-10timesofthatofthegenerator,butalsoitrequiresthattransformersshouldhavegoodperformances,safeandreliableoperation.

Exceptintheelectricpowersystem,thetransformerisalsousedinindustriesandmineswherespecialpowersupplyisneeded,forexamplethetransformerfortheelectricfurnaceinmetallurgy,thetransformerfortherectificationinelectrolysisorchemicalindustry,thetransformerforelectricwelding,thetransformerfortest,thetransformerfortractioninrailwayandthoseproductsbelongingtothecategoryofthetransformersuchasmutualinductor,reactor,extinctioncoiletc.Astheyhavesimilarbasicprincipleandstructureofthetransformerandmuchapplicationandvarieties,theyarecalledtransformer-likeproducts.

II.ClassificationofTransformer

（1）Classifyaccordingtouse,therearepowertransformer,electricfurnacetransformer,rectificationtransformer,electricweldingtransformer,testtransformer,voltage-regulatingtransformer,reactorandmutualinductoretc.

（2）Classifyaccordingtonumberofoutputphase,therearesingle-phasetransformer,three-phasetransformer.

（3）Classifyaccordingtocoolingmedia,therearedrytransformer,oil-immersedtransformerandairtransformer.

（4）Classifyaccordingtocoolingstyle,thereareoil-immersedself-cooledtransformer,oil-immersedair-cooledtransformer,oil-immersedandforcedoilcirculationair-cooledtransformer,oil-immersedandforcedoilcirculationwater-cooledtransformeranddrytransformer.

（5）Classifyaccordingtonumberofwinding,therearedouble-windingtransformer,three-windingtransformerandautotransformer.

（6）Classifyaccordingtostyleofvoltage-regulating,therearefield-freevoltage-regulatingtransformerandloadvoltage-regulatingtransformer.

（7）Classifyaccordingtostructureofironcore,therearecore-typetransformerandshell-typetransformer.

（8）Classifyaccordingtoinsulationleveloftheneutralpoint,therearefullinsulationtransformerandtapinsulationtransformer.

（9）Classifyaccordingtomaterial,therearecopperwiretransformerandaluminumwiretransformer.

III.ModelandRatedDataofTransformer

1.ModelofTransformer

Thevariouskindsofclassificationofthetransformercannotcoverallcharacteristicsofthetransformer.Itshouldhavethemodelofproducttoexpressallitcharacteristic.ThemodelofthetransformerconsistsoftheChinesephoneticalphabetsandArabicnumeralsandeachalphabetordigitstandsforacertainmeaning.

SFSRNZ-□/□

Voltagelevelofhighvoltagewinding（kV）

Ratedcapacity（kVA）

Voltage–regulatingstyle:

itmeansloadvoltage-regulatingifitappearsotherwiseitmeansfield-freevoltage-regulating

“Resisting”hightemperature（itmeansclassFinsulationtemperature

Insulation（cooling）mediaishard“burning”oil

Numberofwindings:

itmeansthreewindingsifitappearsotherwiseitmeansdoublewindings

Coolingstyle:

itmeansair-coolingifitappearsotherwiseitmeansselfcooling

Three-phasetransformer

Exampleofthemodeloftheelectricpowertransformerproduct:

SRNZ-25000/33meansthree-phaseloadvoltage-regulatinghightemperatureresistingliquid-immersedself-cooleddouble-windingpowertransformerwiththeratedhighvoltageof33kVandtheratedcapacityof25000kVA.

2.RatedDataoftheTransformer

（1）TheratedvoltageU1N/U2Nwiththeunitofkilovolt（kV）.Forthethree-phasetransformertheratedvoltagemeansthelinearvoltage.

（2）TheratedcurrentI1N/I2Nwiththeunitofampere（A）.Forthethree-phasetransformertheratedcurrentmeansthelinearcurrent.

（3）TheratedcapacitySN,i.e.theapparentpowerwiththeunitofkilovolt-ampere（kVA）.Ithasrelationswiththeratedvoltageandtheratedcurrentasfollows:

Thesingle-phasetransformerSN=U1NI1N;SN=U2NI2N

Thethree-phasetransformerSN=U1NI1N;SN=U2NI2N

Theratedcapacityofthetransformeristheguaranteedvalueoftheoutputcapacityofthetransformer.Itisdifferentwiththeratedcapacityofthewinding.Theratedcapacityofthedouble-windingtransformeristheratedcapacityofthewindingwhileforthemultiplewindingstransformer,theratedcapacityofeachwindingshouldbespecifiedanditsratedcapacityistheratedcapacityofthemaximumwinding.

InourcountrytheleveloftheratedcapacityofthetransformerisR10preferrednumbersincreasedbythetimesof,onlythatof30kVAandthoseof63000kVAandupwardsaredifferentwithpreferrednumbers.ThelevelsofdetailedcapacitiesareshowninTable1-3.

Table1-3LevelsofRatedCapacitiesofTransformerUnit:

kVA

10

20

（30）

50

63

80

100

125

160

200

250

315

400

500

630

800

1000

1250

1600

2000

2500

3150

4000

5000

6300

8000

10000

12500

16000

20000

25000

31500

40000

50000

63000

（90000）

（120000）

（150000）

（180000）

（240000）

（360000）

Note:

Thesingle-phasetransformertobeconsistedinthethree-phasetransformersethasonly1/3ofthevaluesinthetablewhilethesingle-phasetransformerforotherusehasthesamevaluesinthetable.

（4）TheratedfrequencyfwiththeunitofHertz（Hz）.Inourcountrythemainfrequencyis50Hz.

（5）Theunloadcurrentandunloadloss.Whenthesecondarywindingofthetransformerisopenandtheprimarywindingisappliedbytheratedvoltagewiththeratedfrequencyofsinusoidalwave,thecurrentpassingthroughitiscalledastheunloadcurrentI0.Normallytheunloadcurrentisexpressedbythepercentageoftheratedcurrent.Theactivepowergeneratedwhenthetransformerisoperatedunderno-loadiscalledasunloadlossP0.

（6）Reactancevoltageandloadloss.Whenthesecondarywindingofthetransformerisinshortcircuit,thevoltageappliedupontheprimarywindingtogeneratetheratedcurrenttoflowthroughiscalledasthereactancevoltageUk.Normallythereactancevoltageisexpressedbythepercentageoftheratedvoltage.ThecausedlosscorrespondingtotheratedcapacityunderthereferencetemperatureiscalledastheloadlossPk.

Inaddition,thenameplateofthetransformeralsoshowsnumberofphases,wiringdiagramandgroupstobeconnected,operationstyleandcoolingstyle,totalweightofthetransformer,totalweightofoiletc.

SectionTwoBasicWorkPrincipleofTransformer

I.BasicElectromagneticLaw

1.LawofElectromagneticInduction

SupposeacoilofNturnsinthemagneticfield,incasethemagneticfluxφintercrossedwiththecoilchanges,the inducedelectromotiveforceshallbegeneratedinthecoil.Ifthesupposeddirectionofthe inducedelectromotiveforceandthepositivedirectionofintercrossedmagneticfluxareinaccordancewiththeright-handscrewrule,thentheinducedelectromotiveforceis:

（2-1）

inwhiche—the inducedelectromotiveforce,V;

N—　numberofturnsofthecoil;

dΦ—changeofthemagneticfluxinthecoil,Wb;

dt—timerequiredbythechangeofmagneticlinesofflux,s.

2.MagneticInductionIntensity（magneticfluxdensity）

Themagneticinductionintensitymeansthenumberofmagneticlinesoffluxpassingthroughtheverticalunitarea.Itisusedtojudgeifnumberofthemagneticlinesoffluxisstrongornot.Thecalculationformulaisshownasfollows:

（2-2）

Inwhich,B—magneticinductionintens