轮机英语44课件

MarineEngineeringEnglish《轮机英语》APracticalCourseforEngineersWorkingonBoardShips

MarineElectricalSystemandAutomatizationLesson25ParallelingOperationofAlternators第25课交流发电机并车LearningObjectives:1.Graspsomeusefulwordsandexpressionsinthewholetext.2.Afterstudyingthelesson,heorshewillhaveabetterunderstandingofParallelingOperationofAlternators.3

4part1

NewWordsandExpressions5part2

TextAnalysisLesson25ParallelingOperationThreephasealternatorsarrangedforparalleloperationrequireaconsiderableamountofinstrumentation.#三相交流发电机的并车操作需要很多仪表。Lesson25ParallelingOperationThiswillincludeammeters,watt-meters,voltmeters,frequencymetersandasynchronizingdevice.#包括电流表、功率表、电压表、频率表和同步指示装置。Lesson25ParallelingOperationReversepowerprotectionisprovidedtoalternatorssincecurrentprotectioncannotbeused.#因不能采用逆电流保护，所以发电机装设了逆功率保护。Lesson25ParallelingOperationAlternativelyvarioustripsmaybeprovidedintheeventofprimemoverfailuretoensurethatthealternatordoesnotactasamotor.#或者装设各种脱扣机构，万一在原动机故障时，确保发电机不能按电动机工作。Lesson25ParallelingOperationTheoperationofparallelingtwoalternatorsrequiresthevoltagestobeequalandalsoinphase.#发电机并车运行需要电压相等且同相。Lesson25ParallelingOperationThealternatingcurrentoutputofanymachinesisalwayschanging,sofartwomachinestooperatetogethertheirvoltagesmustbechangingatthesamerateorfrequency,andmustbereachingtheirmaximum(oranyothervalue)together.#交流输出总是在改变，因此，对欲并车的两台发电机而言，它们的电压必须以相同的变化率或频率变化，并且必须同时达到最大值(或其它值)。Lesson25ParallelingOperationTheyarethensaidtobe“inphase”.#此时我们就说它们“同相”。Lesson25ParallelingOperationUseisnowadaysmadeofasynchroscopewhenparallelingtwoACmachines.#现今，当进行并车时使用同步指示器。Lesson25ParallelingOperationThesynchroscopehastwowindingswhichareconnectedonetoeachsideoftheparallelingswitch.#同步指示器有两组绕组，每组与并车开关一侧相连。Lesson25ParallelingOperationApointerisfreetorotateandismovedbythemagneticeffectofthetwowindings.#同步指示器指针可自由转动并且受两个绕组的磁效应而动作。Lesson25ParallelingOperationWhenthetwovoltagesuppliesareinphasethepointerisstationaryinthe12o’clockposition.#当两组输出电压同相时，指针停在12点位置不动。Lesson25ParallelingOperationIfthepointerisrotatingthenafrequencydifferenceexistsandthedialismarkedforclockwiserotationFASTandanti-clockwiserotationSLOW,thereferencebeingtotheincomingmachinefrequency.#若指针在转动，则频率不相同，在表盘上标明顺时针转“快”，逆时针转“慢”，其参考是待并机频率。Lesson25ParallelingOperationToparallelanincomingmachinetoarunningmachinethereforeitisnecessarytoensurefirstlythatbothvoltagesareequal.#为了将一台发电机并入正在运行的发电机电网，首先必须确保两者电压相等。Lesson25ParallelingOperationVoltmetersareprovidedforthispurpose.Secondlythefrequenciesmustbebroughtintophase.#为此设有电压表。其次，频率必须同相。Lesson25ParallelingOperationInpracticethesynchroscopeusuallymovesslowlyintheFASTdirectionandtheparallelingswitchisclosedasthepointerreachedthe11o’clockposition.在实际操作中，通常在同步指示器指针按“快”的方向缓慢转动到11点位置时合闸。

Lesson25ParallelingOperationThisresultsintheincomingmachineimmediatelyacceptingasmallamountofload.这导致待并发电机能立即承担少量负荷。Lesson25ParallelingOperationAsetofthreelampsmaybeprovidedtoenablesynchronizing.#也可用一组三个指示灯实现同步操作。23灯光明暗法

Introduction(Backgroundknowledge)

24灯光旋转法

Introduction(Backgroundknowledge)

Lesson25ParallelingOperationThesequencemethodoflampconnectionhasakeylampconnectedacrossonephasewithtwootherlampscrossconnectedovertheotherphases.#指示灯连结的顺序是，其中主灯跨接于同名相，而另两个灯分别连接于异名相。Lesson25ParallelingOperationIfthefrequenciesofthemachinesaredifferentthelampswillbrightenanddarkeninrotation,dependingupontheincomingfrequencybeingFASTorSLOW.#若发电机频率不同，则灯泡按转向发生明暗变化，取决于待并机频率的快慢。Lesson25ParallelingOperationThecorrectmomentforsynchronizingiswhenthekeylampisdarkandtheothertwoareequallybright.#并车操作的正确时机是当主灯变暗而其它两灯等亮的时候。Lesson25ParallelingOperationIfthetwomachineshavebeenoperatedinparallel,thespeed-controllingswitchofthe“in-coming”

machine

willbehandledslightlytomakeit

runwithsomeload.#如果两台机组并联运行，待并机的速度控制开关将被轻轻操作，以使其带有一些负载运行。Lesson25ParallelingOperationThedivisionofthekilowattloadbetweentwoalternatorsoperatinginparalleliscontrolledbythesettingsandcharacteristicsof

their

primemovers’governors.#并联运行的两台交流发电机之间的有功负荷分配由其原动机调速器的设置和特性控制。Lesson25ParallelingOperationWhen

itisnecessarytomakeonemachine

removefromtheparalleloperation,thefirststepinde-parallelingistoremovetheloadfrom“off-going”

machine.#当需要从并联运行中移除一台发电机时，解列的第一步是移除待解列机组上的负载。Lesson25ParallelingOperationItisimportanttolowertheloadofthe“off-going”

machine

andraisetheloadoftherunningmachine

stepbystepandatthesametimethefrequencyof

thebusbar

iskeptconstant.#重要的是要逐步降低待解列机组的负载，提高运行机组的负载，同时保持母线的频率恒定。Lesson25ParallelingOperationWhentheload

ofthe“off-going”

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

machinewillberemovedfromtherunning

machine.#当待解列机组的负载低于10%额定值时，负载转移将停止，按下“分闸”按钮。然后，将从运行机上移除解列机。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