MarineEngineeringEnglish《輪機(jī)英語(yǔ)》APracticalCourseforEngineersWorkingonBoardShips

MarineElectricalSystemandAutomatizationLesson25ParallelingOperationofAlternators第25課交流發(fā)電機(jī)并車(chē)LearningObjectives:1.Graspsomeusefulwordsandexpressionsinthewholetext.2.Afterstudyingthelesson,heorshewillhaveabetterunderstandingofParallelingOperationofAlternators.3

4part1

NewWordsandExpressions5part2

TextAnalysisLesson25ParallelingOperationThreephasealternatorsarrangedforparalleloperationrequireaconsiderableamountofinstrumentation.#三相交流發(fā)電機(jī)的并車(chē)操作需要很多儀表。Lesson25ParallelingOperationThiswillincludeammeters,watt-meters,voltmeters,frequencymetersandasynchronizingdevice.#包括電流表、功率表、電壓表、頻率表和同步指示裝置。Lesson25ParallelingOperationReversepowerprotectionisprovidedtoalternatorssincecurrentprotectioncannotbeused.#因不能采用逆電流保護(hù)，所以發(fā)電機(jī)裝設(shè)了逆功率保護(hù)。Lesson25ParallelingOperationAlternativelyvarioustripsmaybeprovidedintheeventofprimemoverfailuretoensurethatthealternatordoesnotactasamotor.#或者裝設(shè)各種脫扣機(jī)構(gòu)，萬(wàn)一在原動(dòng)機(jī)故障時(shí)，確保發(fā)電機(jī)不能按電動(dòng)機(jī)工作。Lesson25ParallelingOperationTheoperationofparallelingtwoalternatorsrequiresthevoltagestobeequalandalsoinphase.#發(fā)電機(jī)并車(chē)運(yùn)行需要電壓相等且同相。Lesson25ParallelingOperationThealternatingcurrentoutputofanymachinesisalwayschanging,sofartwomachinestooperatetogethertheirvoltagesmustbechangingatthesamerateorfrequency,andmustbereachingtheirmaximum(oranyothervalue)together.#交流輸出總是在改變，因此，對(duì)欲并車(chē)的兩臺(tái)發(fā)電機(jī)而言，它們的電壓必須以相同的變化率或頻率變化，并且必須同時(shí)達(dá)到最大值(或其它值)。Lesson25ParallelingOperationTheyarethensaidtobe“inphase”.#此時(shí)我們就說(shuō)它們“同相”。Lesson25ParallelingOperationUseisnowadaysmadeofasynchroscopewhenparallelingtwoACmachines.#現(xiàn)今，當(dāng)進(jìn)行并車(chē)時(shí)使用同步指示器。Lesson25ParallelingOperationThesynchroscopehastwowindingswhichareconnectedonetoeachsideoftheparallelingswitch.#同步指示器有兩組繞組，每組與并車(chē)開(kāi)關(guān)一側(cè)相連。Lesson25ParallelingOperationApointerisfreetorotateandismovedbythemagneticeffectofthetwowindings.#同步指示器指針可自由轉(zhuǎn)動(dòng)并且受兩個(gè)繞組的磁效應(yīng)而動(dòng)作。Lesson25ParallelingOperationWhenthetwovoltagesuppliesareinphasethepointerisstationaryinthe12o’clockposition.#當(dāng)兩組輸出電壓同相時(shí)，指針停在12點(diǎn)位置不動(dòng)。Lesson25ParallelingOperationIfthepointerisrotatingthenafrequencydifferenceexistsandthedialismarkedforclockwiserotationFASTandanti-clockwiserotationSLOW,thereferencebeingtotheincomingmachinefrequency.#若指針在轉(zhuǎn)動(dòng)，則頻率不相同，在表盤(pán)上標(biāo)明順時(shí)針轉(zhuǎn)“快”，逆時(shí)針轉(zhuǎn)“慢”，其參考是待并機(jī)頻率。Lesson25ParallelingOperationToparallelanincomingmachinetoarunningmachinethereforeitisnecessarytoensurefirstlythatbothvoltagesareequal.#為了將一臺(tái)發(fā)電機(jī)并入正在運(yùn)行的發(fā)電機(jī)電網(wǎng)，首先必須確保兩者電壓相等。Lesson25ParallelingOperationVoltmetersareprovidedforthispurpose.Secondlythefrequenciesmustbebroughtintophase.#為此設(shè)有電壓表。其次，頻率必須同相。Lesson25ParallelingOperationInpracticethesynchroscopeusuallymovesslowlyintheFASTdirectionandtheparallelingswitchisclosedasthepointerreachedthe11o’clockposition.在實(shí)際操作中，通常在同步指示器指針按“快”的方向緩慢轉(zhuǎn)動(dòng)到11點(diǎn)位置時(shí)合閘。

Lesson25ParallelingOperationThisresultsintheincomingmachineimmediatelyacceptingasmallamountofload.這導(dǎo)致待并發(fā)電機(jī)能立即承擔(dān)少量負(fù)荷。Lesson25ParallelingOperationAsetofthreelampsmaybeprovidedtoenablesynchronizing.#也可用一組三個(gè)指示燈實(shí)現(xiàn)同步操作。23燈光明暗法

Introduction(Backgroundknowledge)

24燈光旋轉(zhuǎn)法

Introduction(Backgroundknowledge)

Lesson25ParallelingOperationThesequencemethodoflampconnectionhasakeylampconnectedacrossonephasewithtwootherlampscrossconnectedovertheotherphases.#指示燈連結(jié)的順序是，其中主燈跨接于同名相，而另兩個(gè)燈分別連接于異名相。Lesson25ParallelingOperationIfthefrequenciesofthemachinesaredifferentthelampswillbrightenanddarkeninrotation,dependingupontheincomingfrequencybeingFASTorSLOW.#若發(fā)電機(jī)頻率不同，則燈泡按轉(zhuǎn)向發(fā)生明暗變化，取決于待并機(jī)頻率的快慢。Lesson25ParallelingOperationThecorrectmomentforsynchronizingiswhenthekeylampisdarkandtheothertwoareequallybright.#并車(chē)操作的正確時(shí)機(jī)是當(dāng)主燈變暗而其它兩燈等亮的時(shí)候。Lesson25ParallelingOperationIfthetwomachineshavebeenoperatedinparallel,thespeed-controllingswitchofthe“in-coming”

machine

willbehandledslightlytomakeit

runwithsomeload.#如果兩臺(tái)機(jī)組并聯(lián)運(yùn)行，待并機(jī)的速度控制開(kāi)關(guān)將被輕輕操作，以使其帶有一些負(fù)載運(yùn)行。Lesson25ParallelingOperationThedivisionofthekilowattloadbetweentwoalternatorsoperatinginparalleliscontrolledbythesettingsandcharacteristicsof

their

primemovers’governors.#并聯(lián)運(yùn)行的兩臺(tái)交流發(fā)電機(jī)之間的有功負(fù)荷分配由其原動(dòng)機(jī)調(diào)速器的設(shè)置和特性控制。Lesson25ParallelingOperationWhen

itisnecessarytomakeonemachine

removefromtheparalleloperation,thefirststepinde-parallelingistoremovetheloadfrom“off-going”

machine.#當(dāng)需要從并聯(lián)運(yùn)行中移除一臺(tái)發(fā)電機(jī)時(shí)，解列的第一步是移除待解列機(jī)組上的負(fù)載。Lesson25ParallelingOperationItisimportanttolowertheloadofthe“off-going”

machine

andraisetheloadoftherunningmachine

stepbystepandatthesametimethefrequencyof

thebusbar

iskeptconstant.#重要的是要逐步降低待解列機(jī)組的負(fù)載，提高運(yùn)行機(jī)組的負(fù)載，同時(shí)保持母線的頻率恒定。Lesson25ParallelingOperationWhentheload

ofthe“off-going”

machineislowerthan10%ratedvalue,theload-shiftingwillbestopped,pressthe“OPEN”button.Thenthe“off-going”

machinewillberemovedfromtherunning

machine.#當(dāng)待解列機(jī)組的負(fù)載低于10%額定值時(shí)，負(fù)載轉(zhuǎn)移將停止，按下“分閘”按鈕。然后，將從運(yùn)行機(jī)上移除解列機(jī)。part3

Exercise&ExaminationHandheldphasesequenceindicatorsareusefulwhen_____.A.preparingtoparallelalternators B.connectinglightingbranchcircuitsC.troubleshootingDCmotorsD.connectingshorepowerlinestotheshipWhenparallelingtwoalternatorsusingthreesynchronizinglamps,theflickeringofallthreelampsbecomesprogressivelyslowerandslower.Thismeansthe_____.A.frequencyoftheincominggeneratorisapproachingthatofthebusB.frequencyoftheincomingalternatorislessthanthatofthebusC.phaserotationoftheincomingalternatorsisoppositetothatofthebusD.terminalvoltageoftheincomingalternatorisapproachingthatofthebusEqualizationofthepowerfactorsoftwoalternatorsoperatinginparallelisaccomplished_____.A.manually,byadjustingthegovernorcontrolsB.automatically,byautomaticvoltageregulatorsC.manually,adjustingtheoutputofcurrenttransformersD.automatically,bythede