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APPROVAL ISSUE Module 234-9 THE TURNING GEAR

APPROVALISSUEM odule234-9 Course234-TurbineandAuxiliaries-ModuleNi neNOlES& )Foreachoftheturbineoperatingstatesliste dbelow,statethepurpose(s)oftheturninggea roperation:i)Duringturbinestanup(2);ii)W hileshuttingdowntheturbine(I).b)Foreacho ftheoperatingstateslistedinpoint(a),desc ribeturn-inggearoperation,addressingthef ollowingpoints:i)Whentheturninggearmotor is startedup/ sbutdown;ii)Whentheturninggearisengagedt o/disengagedfromthetorbinegeneratorrotor ;iii)Thereasonwhyduringturbinerunupthetu rninggearmo-torcontinuesrunningforsometi meaftertheturninggearhasdisengagedfromth eturbinegenemtorrotor.

APPROVAL ISSUE Module 234-9 Course 234 - Turbine and Auxiliaries - Module Nine NOlES &REFERENCES THE TURNING GEAR OBJECTIVES: Aftercompleting this module youwillbeable.to: 9.1 a) Foreach ofthe turbine operating states listedbelow, state the

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Transcription of APPROVAL ISSUE Module 234-9 THE TURNING GEAR

1 APPROVALISSUEM odule234-9 Course234-TurbineandAuxiliaries-ModuleNi neNOlES& )Foreachoftheturbineoperatingstatesliste dbelow,statethepurpose(s)oftheturninggea roperation:i)Duringturbinestanup(2);ii)W hileshuttingdowntheturbine(I).b)Foreacho ftheoperatingstateslistedinpoint(a),desc ribeturn-inggearoperation,addressingthef ollowingpoints:i)Whentheturninggearmotor is startedup/ sbutdown;ii)Whentheturninggearisengagedt o/disengagedfromthetorbinegeneratorrotor ;iii)Thereasonwhyduringturbinerunupthetu rninggearmo-torcontinuesrunningforsometi meaftertheturninggearhasdisengagedfromth eturbinegenemtorrotor.

2 Iv)Thereasonwhyduringturbinerundownthetu rninggearmotoris )Foreachoftheoperatingstateslistedbelow, descnbethead-verseconsequences/operating concernscausedbyfailuretotumtheturbinege neratorrotorasrequired:i)Duringturbinest anup(2);ii)Whileshuttingdowntheturbine(3 ). )i)Statethegeneraloperatoractionthatshou ldbetaken,toprotecttheturbine, ) )Describethreealternatemethodsofturningt heturbinerotorthatcan beusedundertheseoperatingcircumstances. :>Page2 :>Page4~Pages3(startup),and4-5(shtdown) :>Pages3-4 :>Pages5-6 :>Page6 :>Pages7-8 Page1 Course234-TurbineandAuxiliaries-ModuleNi neAPPROVALISSUENOTES&REFERENCESPage8<=> )i)<=>Page2b)Assumingthattheturbinerotorhasbee nleftstationaryfortoolongduringthecooldo wnthatfoilowsa turbinerundown:i)Stateoneimportantprecau tionthatmustbetakenpriortoanemptingtotur ntherotorbytheturninggearwhenitbe-comesa vailable;ii)Explainthereasonwhythispreca utionisnecessary;iii)Statetherequiredact ionif,asaresultofthisprecaution,thetumiI iggearmustnotbeused.

3 INSTRUCTIONALTEXTINTRODUCTIONI ntheturbinecourseswhichyouhavetakensofar ,thefunctionandstruc-tureofa typicalturninggearasweilasthephenomenaof t\ ,anyattempttorunuptheturbinewithanexcess ivelydeformedshaftisboundtofailbecausehi ghvibra-tionwouldsoonerorlaterfOICea ,theturbinegenerator ,rotorandcasinghoggingwoulddevelopduetot henna!stratificationof. ModuleNineOperationToachievethesetwoobje ctives,theturninggearis ,thedurationortuminggearoperationmustbee noughto:-Straightenuptheturbinegenerator shaftsuchthattheHPturhinerotoreccentrici tyiswithintheacceptablelimit,and-Meetthe additionaltequirements(ifany) straight, , ,theminimumtimedependsonthedurationofthe precedingshutdownduringwhichtheturbinege neratorrotorwasleftstationary, ,itsmotoris , ,this- alongwithmanyotherstartupactivities- , ,however,keepsrunninguntilturbinespeedre achesa certainlevel , enoughpriortorunupcausesthefollowingadve rseconsequences/operatingconcernsduetotu rbinegen.

4 ,andparticularlywhilepassingthrougha criticalspeedrange,thevibrationscanbecom eabnormallyNOTES&REFERENCES~ ) ~ )i) Rubbingdamageisde )ii)~ )~ ,in~heextremecase, Duringturbinestartup,theturninggearisuse dinordertoroUoutshaftdefonnationsbeforen mupbegins,andtoenableuniformptewanningof theturbine generator. Toachievetheseobjectives, continuedlongenoughto reducetheHPturbinerotoreccentricityto a satisfactorylevel,andto meetanyadditionaltimerequirementsasspeci fiedintheappropriateopetatingmanual. Assoonassteamis3dnUttedtothetmbine,causi ngitsspeedtoin-crease, ~lainturbinespeedis Failuretousetheturninggearasrequiredduri ngturbinestartupmayre-sultin turbine1rip, ,therotorwereleftstationarywhiletheturbi neis ,however,remainsdisengagedfromtheturbine gener-atorshaftuntilturbinespeedhasdecre asedenough.

5 Theearlystartupoftheturninggearmotor(atl eastsevetaiminutesbeforetheturninggearis ac-tuallyneeded)givestheoperatortimetore spond,shouldthemotorfailtostartThisupset is , ,APPROVALISSUEC ourse234-TurbineandAuxiliaries-ModuleNin etherotormustcometoafullstop, certainlevel"'.Atthislowtem-perature, ,theturninggearmotorisswitchedoff, fastprocess, , , ,thesmallerthetemperaturegradientsinside themachine,andhence, 'inthefollowingadverseconsequences/ , ,andpossiblybearings, , spareone(ifany) intheproperperspective,it mustbestatedthatinCANDU stations,asopposedtoconventionalthennalp lants,chancestorNOlES& ,lOO 150 C,dependingonthestation.

6 ~ )ii)Page5 Comse234-TurbineandAuxiliaries-ModuleNin eAPPROVALISSUENOTES& 'CcOmparedwith535 ~..Refertotheappropriateeleclricalcourse ifyouarenolfamiliarwithhowthegeneratorro torfieldwind ingsareheldinsidethe1"nln1" *.Asaresult,themaximumtop-t~'t:xJqomtemp eraturedifference,thatcanfonnwbentheroto risleftstationary, 'Intheprecedingsections, ,excessiveoperationoftheturninggearshoul dbeavoidedasthismay,intbelongrun, frettingofthegeneratorrotorfieldwind-ing sagainsttheslotwalls .Atbigbturbinespeeds, , ,undertheirownweight,thewindingshavea , , Thepurposeofturninggearoperationwhileshu ttingdowntheturbineistopreventrotorhoggi ng.

7 Ifallowedtohappen,thiscoulddelaythesubse quentturbinestartupun-ti! ,andpossiblybearings, butextremelyunlikely- case, prolongedoutagetorepair!replacetherotorw ouldresult Topreventexcessivehoggingwhileshuttingdo wntheturbine, ,afterturbinespeedhasdecreasedtozeroorne arlyzero, re-spond, certainlimit Excessiveuseofthetmninggearisnotrecommen ded, <=>Pages11-13 TURNING GEAR :-Theactionthattheoperatorshouldtakewhen theturninggearmotorfailstostartduringtur binerundown;-Alternatemethodsofturningth eturbinegeneratorrotor;-Actionsthatshoul dhetakeniftherotoris leftSlationaryfortoolongduringthecooldow nthatfollowsa ,duringturbinerundowntheturninggearmotor shouldstanatacertainturbinespeed,atleast severalminutesearlierthanthe , , , , , ,theleverhasa , theleverishungontheturninggearcasingorne arby, ,whenneeded, ,it <=> )Page7 Course234-TurbinelindAuxiliariel_ ModuleNineAPPROVALISSUENOTES& )<=>Morethan5-30minutes,dependinj;onthestati onllIIdthehighestHPtur-binemetaltemperat ure.

8 , (availableonlyinsomeunits) , , ~bottom& ,forsomereason,theturbinerotorwereleftst ationaryfortoolong duringitscooldownperiod, ,precautionsmustbetakenpriortoanattemptt oturntheturbinerotorbytheturninggearwhen it (dependingonthestation).Ifthehandbar-rin gindicatesthattherotorisbentexcessively , , ,therotorshouldberotatedbyhandbarringand checkedforstraightness, , ,suchcooldownis effec-tiveinreducingthehoggingtoa levelat , Iftheturninggearfailstostartduringturbin erundown, includehandbarringoruseofa ,anauxiliaryturninggearisalsoavailable. ITtheturbinerotOrwereleftstationaryforto olongbeforeitscooldowniscomplete,precaut ionsmustbetakenpriortoputtingitonturning gearwhenitbeco~ Thisis achievedbyhandbaningtheturbineforonefull turnwhilecheckingforabnonnallyhighresist ancetoturningand/orexcessiveec~centticit yoftheHPturbinerotor,dependingonthestati on.

9 Iftherotorisbelievedtobebentexcessively, ,therequiredactionisjusttoleavetheturbin erotorstationllI)' verylikelyto reducetheturbinehoggingtoa {=> :a)Thetwoobjectivesofturninggearoperatio nare:i)ii)b)Ifturbineronupbeganpremature ly, ,thefollowingadverseconsequences/operati ngconcernswouldresult:i)ii)c)Toavoidthes econsequences,theturninggearshouldbeoper atedasfollows:i)It is started_ii)Itdisengagesfromtheturbinegen eratorrotorwhen__iii) :a)ThePUIJlOseofturninggearoperationis_P age11 COUl'lle234-TurbineandAuxiliaries- Module NineAPPROVALISSUENOTES&REFERENCESb)Inade quateuseof-theturninggearresultsinthefol lowingadverseconsequences/operatingconce rns:i)il)iii)c)Theturninggearshouldbeope ratedasfollows.}

10 I)It is stoned_il)It is engagedtotheturbinegeneratorrotorwhen_ii i)Itis )Thereasonwhyduringturbineronuptheturnin ggearmotorcon-tinuesrunningforsometimeaf terthetlnninggearhasdisengagedfromthetur binegeneratorrotoris_b)Thereasonwhydurin gturbinerundowntheturninggearmotorisstan etiupsornetimebeforetheturninggearis actuallyneededtodrivetheturbinegenerator rotoris_Page12 APPROVALISSUEC ourse234-TurbineandAuxiliaries-ModuleNin eNOlES& )Themajoroperationalconcerncausedbyexces siveuseoftheturninggearisthatitpromotes_ duetoaphenomenonknownas_b) turbinerundowntheturninggearIOOtorfailed tostartandit turnedoutthatit :a)Toprotecttheturbine,theoperatorshould _b)Dependingonthestation,oneortwoofthefo llowingalternatemethodsofturningtheturbi negeneratorrotorisIareavailable:i)Method :_Description:_il)Method:_Description:_P age13 Course234-TurbineandAuxiliaries-ModuleNi neAPPROVALISSUENOTES&REFERENCESiii)Metho d:_Description.


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