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INTERNATIONALSTANDARDIEC45

SteamTurbines

Part1:Specifications

Contents

FOREWORD 2

INTRODUCTION 2

1 Scopeandobject 3

2 Normativereferences 3

3 Termsanddefinitions 3

4 Guarantees 9

5 Governor(control) 10

6 Operationandmaintenance 13

7 Components 17

8 Foundationsandbuildings 19

9 Feedpumpdrives 20

10 Turbineauxiliarysystems 21

11 Instrumentation 23

12 Protection 25

13 Vibration 29

14 Noise 30

15 Tests 30

16 Deliveryandinstallation 31

17 Designinformationtobesuppliedbythepurchaser 31

18 Designinformationtobeprovidedbythesupplier 35

19 Turbineplantwithregenerativefeedheating 36

AnnexAElectronicgovernors

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FOREWORD

1) The formal decision or agreement of the IEC on technical matters, prepared by TechnicalCommittees on which all the National Committees having a special interest therein arerepresented, expressed, as nearly as possible, an international consensus of opinion on thesubjectsdealtwith.

2) They have the form of recommendations for international use and they are accepted by theNationalCommitteesinthatsense.

3) In order to promote international unification, the IEC expresses the wish that all NationalCommitteesshouldadoptthetextoftheIECrecommendationfortheirnationalrulesinsofarasnational conditions will permit. Any divergence between the IEC recommendation and thecorrespondingnationalrulesshould,asfaraspossible,beclearlyindicatedinthelatter.

ThispartofInternationalStandardIEC45hasbeenpreparedbyIECTechnicalCommitteeNo.5:SteamTurbines.

Thetextofthispartisbasedonthefollowingdocuments.

SixmonthsRules ReportonVoting

5(CO)28 5(CO)31

FullinformationonthevotingfortheapprovalofthispartcanbefoundintheVotingReportindicatedintheabovetable.

AnnexAformsanintegralpartofthispartofIEC45.

INTRODUCTION

ThefirsteditionofIEC45wasissuedin1931.Subsequentversionsweremade,thelastbeingin1970.Sincethen,intensivedevelopmenthasresultedintheavailabilityofmorehighlyratedturbines.

The development of turbines suitable for usewithwatercooled nuclear reactor hasproceeded inparallel,resulting in theproductionof large turbines forusewithsteamwhichisinitiallydrysaturatedorslightlywet.

Thedemandsmadeupon turbinecontrolsystemshave increasedsimultaneouslywiththe development of new control technologies, such as electrohydraulic systems.Increased reliably, higher standards of dynamic performance, suitably for two shiftoperation, and increased attention to health and safety are among the aspects nowrequiringhighstandardsofachievement.

Ithasthereforebecomenecessarytospecifyaturbineinmoredetailthanwasformerlyneeded. In consequence, this part of IEC 45 has been completely rewritten, and isaccordinglymorecomprehensivethanearliereditions.

Wheneverpracticable,thispartof IEC45takes intoaccountthescope forapplyingtosmallerturbinesdevelopmentsoriginallyintendedforlargermachines,withoutimplyingthatsuchapplicationswouldalwaysbenecessaryoradvantageous.

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IEC45

SteamTurbines

Part1:Specifications

1 ScopeandObjectThis part of international standard IEC 45 is applicable primarily to steamturbinesdrivinggenerators forelectricalpowerservices.Someof itsprovisionsarerelevanttoturbinesforotherapplications.

Thepurposeofthispartistomakeanintendingpurchaserawareofoptionsandalternatives which hemay wish to consider, and to enable him to state histechnicalrequirementsclearlytopotentialsuppliers.

2 NormativeReferencesThefollowingstandardscontainprovisionswhich,throughreferenceinthistext,constitute provisions of this part. At the time of publication, the editionsindicated were valid. All standards are subject to revision, and parties toagreementsbasedon thispartareencouraged to investigate thepossibilityofapplyingthemostrecenteditionsofthestandardsindicatedbelow.MembersofIECandISOmaintainregistersofcurrentlyvalidinternationalstandards.

IEC651 :1979,Soundlevelmeters.

IEC9531 :1990,RulesforsteamturbinethermalacceptancetestsPart1:MethodA.

IEC9532 :1990,RulesforsteamturbinethermalacceptancetestsPart2:MethodB.

IEC2372 :1974,Mechanicalvibrationofmachineswithoperating speedsfrom10to200rev/s.basisforspecifyingevaluationstandards.

ISO 7919 1: 1986, Mechanical vibration of nonreciprocating machines MeasurementsonrotatingshaftsandevaluationPart1:Generalguidelines.

3 TermsandDefinitionsForthepurposeofthispart,thefollowingtermsanddefinitionsapply:

3.1 Turbinetype

Superheatturbine:Aturbinewhoseinitialsteamissignificantlysuperheated.

Wetsteamturbine:Aturbinewhoseinitialsteamissaturatedornearlyso.(Alsoreferredtoassaturatedsteamturbine)

Reheatturbine:Aturbinefromwhichthesteamisextractedpartwaythroughtheexpansion,reheated(oneormoretimes)andreadmittedtotheturbine.

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Nonreheatturbine:Aturbineinwhichthesteamisnotreheated.

Mixedpressure turbine: A turbine provided with separate inlets for steamsuppliedattwoormorepressures.

Backpressure turbine:A turbinewhose exhaust heatwill be used to provideprocessheat,andwhoseexhaustisnotdirectlyconnectedtothecondenser.Theexhaustpressurewillnormallybeaboveatmosphericpressure.(Alsoreferredtoasanoncondensingturbine)

Condensing turbine: A turbine whose exhaust is directly connected to acondenser.Theexhaustpressurewillnormallybebelowatmosphericpressure.

Regenerative cycle turbine: A turbine from which some of the steam isextractedpartwaythroughtheexpansioninordertoheatfeedwater.

Extractionturbine:Aturbine inwhichsomeofthesteam isextractedpartwaythroughtheexpansioninordertoprovideprocesssteam.Iftheturbineincludesmeans for controlling the pressure of the extracted steam, it is called acontrolled(orautomatic)extractionturbine.

Combined cycle: A combination of boiler, steam turbine and gas turbine, inwhich the gas turbine exhaust normally contributes to the heat input to thesteamcycle.

Singleline combinecycle:A combinedcycleplant inwhich the steam turbineandgasturbinebothdrivethesamegenerator.Itisnotpossibletosegregatetheseparateoutputsofthesteamturbineandthegasturbine;anddefinitions,suchasthoseofheatrateoroutputgivenlaterinthisstandard,nolongerapply.

Note:thetermin3.1maybecombinedtodefinethefeaturesofanyparticularunit.

3.2 Methodofinitialsteamadmission

Full arc: All of the governing (control) valves supply steam uniformly to theadmissioninletbeltofthefirststage.

Partial arc: The inlet belt to the first stage is divided into discrete arcs ofadmission,steambeingsuppliedseparatelytoeacharcthrough,normally,onegoverningvalve;governingvalvesoperatewhollyorpartiallyinsequence.

3.3 Conditions

Terminal conditions: The terminal conditions for a steam turbine or turbinegeneratoraretheconditionsimposedontheplantattheirterminatingpointsofthecontract.Thesemaytypicallycomprise:

- Initialsteamconditions- Hotreheatsteamconditions- Coldreheatpressure- Finalfeedwatertemperature- Exhaustpressure- Poweroutput- Speed- Extractionrequirements

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Specifiedorratedterminalconditions:Theconditionsattheterminatingpointsoftheturbineorturbinegeneratorcontract,withwhichspecifiedoutputand/orheat rate shall be stated and/or guaranteed. Note that some nuclear steamgeneratorssupplysteamatapressurewhichincreasesasloadreduces,andtheturbinedesignmustallowforthis.

Steam conditions: The conditions which define the thermodynamic state ofsteam, normally (static) pressure and temperature or dryness fraction (orquality).Steampressureshouldalwaysbequotedinabsoluteunits,notasgaugepressure.

Initialsteamconditions:Thesteamconditionsatinlettothemainstopvalves.

Maximumsteamconditions:Thehigheststeamconditionsatwhichtheturbineisrequiredtooperatecontinuously.

Note:Thehighest steam conditions shouldnotexceed thosepermittedby6.2.a)and6.2.b).

Induction steam conditions: The steam conditions of any additional steamenteringtheturbineatanypressurelowerthantheinitialpressure.

Dual steam conditions: The combination of initial and induction steamconditionsappropriatetoamixedpressureturbine.

Reheatsteamconditions:Thesteamconditionsatthe inlettothereheatstopvalves.(Alsoreferredtoashotreheatsteamconditions)

Coldreheatsteamconditions:Thesteamconditionsattheoutletoftheturbineprecedingthereheater.

Extractionsteamconditions:Thesteamconditionsattheextractionconnectionsoftheturbine,ofsteamextractedforfeedheatingorprocesspurposes.

Exhaust conditions:The steam conditionsat theexhaust connection from theturbine.

Note:Useoftheworddesigninrespectofanysteamconditions,poweroutput,speed,etc.,shouldbeavoidedinthecontractdocuments.Thisterminologyshouldonlybeappliedtothevaluesused indesigncalculationssuchasthedesignpressureforapressurevessel.

3.4 Speed

Ratedspeed:Thespeedatwhichtheturbineisspecifiedtooperateatitsratedoutput.

Maximum continuous speed: The upper limit of the operating speed of theturbineforcontinuousservice.

Overspeedtripsetting:Thespeedatwhichtheoverspeedtripissettooperate.

Temporaryspeedrise:Thetransient increase inturbinespeedfollowinga loadrejection,withthespeedgoverningsystems inoperation.Theratedtemporaryspeedriseappliesiftheratedoutputisrejectedattheratedspeed.

Maximum transient speed:Maximum rotational speed following rejection ofmaximumcapabilitybydisconnecting thegenerator from theelectrical system

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(with auxiliary supplies previously disconnected) and the speed governing(control)systeminoperation.

Permanentspeedrise:Thefinalsteadystateincreaseinturbinespeedfollowingaloadrejection,withnormalgovernorcontrol.

Maximum speed rise:The transient increase in turbinespeed followinga loadrejection,withthespeedgoverningsystem inoperativeandtheoverspeedtripoperative.Theratedmaximumspeedriseappliesiftheratedoutputisrejectedatratedspeed.

3.5 PowersNote:All thesepowersoroutputs refer tooperationof the turbineat rated terminalconditions(exceptwherestatedotherwise)

Power:Thepowersuppliedbytheturbineor itsdrivenmachine.Thedefinitionshould state the position ofmeasurement and any deductions for losses orauxiliarypower.(Alsoreferredtoasoutputorload)

Net power at coupling: The power at the turbine coupling, less the powersuppliedtoturbineauxiliariesifdrivenseparately.

Generatoroutput:Poweratthegeneratorterminals,afterthedeductionofanyexternalexcitationpower.

Maximum continuous rating (MCR) (electrical generating set): The poweroutputassignedtotheturbinegeneratorbythesupplier,atwhichtheunitmaybe operated for an unlimited time, not exceeding the specified life, at thespecified terminal conditions. This is the rating which will normally carry aguarantee of heat rate. The governing (control) valveswill not necessarily befullyopen.(Alsoreferredtoasratedoutput,ratedpower,orratedload.)

Maximumcontinuousrating(MCR)(otherthanelectricalgeneratordrives):Thepoweroutputassignedtotheturbinebythesupplier,atwhichtheunitmaybeoperatedforanunlimitedtime,notexceedingthespecifiedlife,atthespecifiedterminalconditions.This is the ratingwhichwillnormallycarryaguaranteeofheatrate.Thegoverning(control)valveswillnotnecessarilybefullyopen.Thepower shall be that delivered at the turbine coupling, or the coupling of thedrivenmachine, asmay be agreed. (Also referred to as rated output, ratedpower,orratedload.)

Maximumcapability:Thepoweroutputthattheturbinecanproducewiththegoverning (control) valves fully open and at the specified terminal conditions.(Alsoreferredasvalvesopencapability)

Maximumoverload capability:Themaximumpoweroutput that theunit canproducewith the governing (control) valves fullyopen, andwith the terminalconditionsspecifiedforoverload,e.g.withfinalfeedwaterheaterbypassed,orwithincreasedinitialsteampressure.

Most economical continuous rating (ECR):Theoutput atwhich theminimumheatrateorsteamrateisachievedatthespecifiedterminalconditions.

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Net electrical power: The generator output (with external extraction powerdeducted)minustheelectricalauxiliarypower.

Electricalauxiliarypower:Powertakenbyturbineandgeneratorauxiliariesnotdriven by the turbine. This will normally include all power used for control,lubrication, generator cooling and sealing. It may also include additionalauxiliariessuchasmotordrivenboilerfeedpumps.Thepurchaserandcontractorshouldagreeonwhichadditionalauxiliariesshouldbeincluded.

3.6 Steamflowrateandsteamrate

Initialsteamflowrate:Theflowrateofsteamatinitialconditionstotheturbine,includinganysteamsuppliedtovalvestems,glands,orbalancepistons,andanysteam supplied to auxiliary plant such as boiler feed pump turbines,steam/steamreheaters,ejectors,etc.

Steamrate:Theratioofinitialsteamflowratetopoweroutput.

3.7 Heatrates

(SeealsoIEC953,wherethedefinitionsaregiveningreaterdetails)

Heatrate:Theratioofexternalheatinputtothecycletopoweroutput.Itisthereciprocalofthermalefficiency.

Guaranteeheatrate:Theheatrateuponwhichtheguaranteeorofferisbasedfor a stated output with the rated terminal conditions and for the cycledescribed in 19.1.Any assumptionwith regard to extraneous flows,makeup,heatadditionorremoval,shallbestated.Inallcases,theformulausedtodefinetheheatrateshallbestatedinthecontract.

Uncorrectedtestheatrate:theheatrateobtainedbyinsertingtestresultsintheformulastatedinthecontract.

Fullycorrectedheatrate:Theheatratewhichwouldhavebeenachievedduringthetest iftheterminalconditionshadbeenasspecified,andallancillaryplantoutsidethesuppliersresponsibilityhadperformedexactlyinaccordancewithitsguarantee.

3.8 Efficiency

Thermal efficiency: The reciprocal of heat rate, and therefore defined as theratio of power output to external heat input to the cycle. If guaranteed, thedefinitionofthermalefficiencyshallbestatedinthecontract.

3.9 Operationalregimes(modes)

Baseloadoperation:Operationatmaximumcontinuousrating(MCR)orahighfractionofthisthroughoutaprolongedperiod.

Twoshiftoperation:OperationatMCRorahigh fractionof this forabout16hoursorlessoutof24hoursperday,theremainingtimebeingshutdown.

Oneshift operation:Operation atMCR or a high fraction of this for about 8hoursoutof24hoursperday,theremainingtimebeingshutdown.

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Load cycling:Operation alternatingbetweenhigh and low levelsof loadon aregularbasis.

Peakloadoperation:Operationathighloadforshortperiods,typically1hourto3hours,attimesofpeakdemand.Thenumberofpeaksperday isnot implied.Theremainingtimeisspentshutdown.

Note:Althoughtheabovedefinitionsareofageneralnature,theymaybemademorespecificbystatingwhethertheturbineisorisnotsubjectedtoperiodicshutdown,which might typically be categorised as a 36 hour shutdown or a 48 hourshutdown.

3.10 Methodsofloadvariation

Constantpressure operation:Operation inwhich the initial steampressure ismaintainedsensiblyconstant,andwhereloadisreducedbygraduallyclosingthegoverning (control) valveseither inparallel (fullarcadmission)or in sequence(partialarcadmission).

Slidingpressureoperation:Operation inwhich load ischangedbyvariationofthe initial steam pressure; the governing (control) valves, which operate inparallel,allremainingattheirfullyopenposition.

Modified slidingpressure:Operation inwhich load changes in the range from100% to about 90% of the rated output are achieved by operating all thegoverning (control) valves in parallel, the initial steam pressure remainingconstant; below about 90% of the rated output changes of load are, wherepracticable, achieved by variations of the initial steam pressure, while thegoverning(control)valvesremainnearthepositioncorrespondingto90%oftheratedoutput

Hybridoperation:Operationofapartialarcadmissionmachineinwhichloadisreduced by sequential closing of the governing (control) valves to a valuecorresponding to theminimumallowablenumberofgoverning (control)valvesremaining fully open, the initial steam pressure remaining constant; furtherreductionof load isachievedbyreduction in initialsteampressurewhilethosegoverning(control)valvesareopenremainatorneartheirfullyopenposition.

Throttlegoverning:Thegoverning(control)valvesoperate inparallel,ornearlyso,thisbeingthenormalmodeoffullarcadmissionturbineinconstantpressureoperation.

Nozzle governing:Thegoverning (control)valves close in sequence, thisbeingthenormalcontrolmodeofapartialarcadmissionturbineinconstantpressureoperation.

3.11 Operationallife

Calendarage:Thetotalelapsed lifeoftheplant,expressed inmonthsoryears,measuredfromfirstsynchronisation.

Running hours: The number of hours duringwhich themachine has been onload.

3.12 Controlandprotection

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Governingsystem:Thecombinationofdevicesandmechanismswhichconvertcontrolsignals intovalvepositions inacharacteristicmanner.This includesthespeed governor, the speed control mechanism, the speeder device (speedchanger),theunloadingsystemsandanysteamvalveoperatingdevices.

Turbinegenerator protection system: The overall system provided to protectthe turbinegenerator from faults within itself or elsewhere in the electricaltransmissionsystem.

Steadystate condition:A conditionwhichhas constantmeanvaluesof speedandloadwithlimitedrandomdeviations.

Stable operation: A system is said to be stable if it achieves a steadystateconditionfollowingaspeedorloaddisturbance.

Steadystate regulation (speed governing droop): Steadystate speed changeexpressedasapercentageofratedspeed,whenthe loadofan isolatedunit ischangedbetween rated loadandzero load,with identicalsettingof thespeedgoverning(control)system,assumingzerodeadband.

Steadystateincrementalspeedregulation(incrementalspeeddroop):Therateof change of steadystate speedwith respect to load at a given steadystatespeedandload,assumingzerodeadband.Thevalueistheslopeofthetangenttothesteadystatespeed/loadcurveattheloadunderconsideration.

Deadbandofthespeedgoverning(control)system:Thetotalmagnitudeofthechange in steadystate speed (expressedaspercentageof rated speed)withinwhich there is no resultant change in the position of the governing (control)valves.Thedeadbandisameasureofthesensitivityofthesystem.

Maximum load inaccuracy or nonlinearity: Themaximum deviation in load,expressed as a percentage of rated load, of the loadspeed curve from thestraight line corresponding to theoverall speeddroop,whenoperatingunderdefined conditions of the control equipment environment (e.g. temperature,humidity)andpowersupply(e.g.voltage,oilpressure).

Governor environmental stability: The change in load, expressed as apercentage of rated load, resulting from a given change of any independentvariable other than set point or speed. Such variables are lapsed time,temperature,vibration,barometricpressure,supplyvoltageandfrequency.

Shorttermstability:Thechange indemanded load,expressedasapercentageofratedload,foranyfixedsetpointandspeedoveranyperiodof30minuteforwhichtheambientconditionsarewithinthedefinedenvelope.

Long term stability: The change in average demanded load, expressed as apercentageofrated load,forfixedsetpointandspeedbetweentwoperiodsof30minutes at an interval of 12months. For both test periods the ambientconditionsshouldbewithintherequiredenvelope,butmaynotnecessarilybecloselysimilar.

4 Guarantees4.1 General

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Guaranteesofseveralkindsmaybestated in thecontract, forexampleon efficiency, heat (or steam) rate, output, or auxiliary power.Guaranteesmay also be required for characteristics such as governing(control)systemfunctions,vibrationlevelornoise.

All guarantees with their provisions shall be stated and formulatedcompletelyandwithoutambiguity.

4.2 Turbineplantthermalefficiencyorheatrateorsteamrate

The guaranteed heat (steam) rate is given on the assumption that theacceptance tests shallbe inaccordancewith theprovisionsof IEC953,includingtheneedforagreementofcorrectionprocedures.ThecontractshallstatewhetherIEC9531orIEC9532willbeused.Theturbineplantthermalefficiencyorheatrateorsteamrateguaranteemay,forexample,beconfinedtoonespecified loadortotheirweightedvaluesataseriesofloads,inaccordancewiththetermsofthecontract.

Where the regenerative feed water heaters are not included in theturbinesupplierscontract,thepurchasershallpreferablysupplywithhisspecificationadrawingofthe feedwaterheatingsystemwithsufficientinformationtoenabletheheatrateguaranteesofthecompletesettobeformulated. Alternatively, the supplier shall state in his tender thenumberanddistributionofthefeedwaterheaters,thefeedwaterheaterterminaltemperaturedifferences,andthepressuredifferencesbetweenthe turbine and theheaters,whichhavebeenused in formulating theguarantee.

Similar steps shall be taken in wetsteam turbines where either themoistureseparators,or the reheaters,orboth,arenot included in theturbinecontract.

Whereregenerativefeedwaterheatersareincluded,therequirementsinclause19shallalsobeapplied.

Theturbinesuppliershallbegiventheopportunityeitherofadjustinghisguarantee inthecontractstage,shouldtheperformanceofplantnot inhissupply,suchasheaters,valves,piping,orpumps,differfromthatonwhichhisguaranteewasbased,orofapplyingagreedcorrectionstothethermalacceptancetestresults.

4.3 Outputorsteamflowcapacity

The turbine shall be demonstrated to provide its rated output, oralternativelyitsratedsteamflowcapacity,whentheterminalconditionsare as specified in the contract. The test shall be carried out inaccordancewiththeprovisionsofIEC953.

4.4 Auxiliaryplantpower

If a guarantee is given on the power consumption of continuouslyrunning auxiliary plant, a list of such plant items shall be agreed. Thepowerconsumptionofeachsuchitemshallbeeithermeasuredwhenthe

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turbineisatspecifiedoutputandspecifiedterminalconditionsoragreedbetweenthepurchaserandthesupplier.

4.5 Steamtables

Thesteam tablesor formulation tobeused for theguaranteesand thecomputation of test results shall be consistent with internationalSkeletonTablesestablishedattheSixthInternationalConferenceonthePropertiesof Steam (ICPS) in1963,and shouldpreferablybebasedonthe 1967 International Formulation Committee (IFC), Formulation forIndustrialUsethatwasapprovedattheseventhICPSin1968.

Theyshallbeagreeduponbythepurchaserandthesupplier,andshallbestatedinthecontract.

4.6 Tolerances

Commercialtolerancesarenotwithinthescopeofthispart.

4.7 Ageing

Anyallowancetobemadefortheeffectonthecorrectedtestheatrate,steam rate or thermal efficiency due to lapse of time since firstsynchronisationshallbemadewithprioragreementbetweenpurchaserandsupplier,andshallbeinaccordancewiththeprovisionofIEC9532.

5 Governing(Control)5.1 Governing(control)system

5.1.1 The turbine governing (control) system shall be capable ofcontrollingthespeedfromstandstillupwards.Thiscontrolmaybemanualorotherwise.

5.1.2 For turbine driving a generator, the turbine governing (control)systemshallbecapableofcontrolling

a) Speedatallloadsbetweennoloadandfullloadinclusive,inastablemannerwhenthegeneratorisoperatedisolated

b) The energy input to the interconnected system, in a stablemanner,whenthegeneratorisoperatinginparallelwithothergenerators(see6.1.1).

5.1.3 Thegovernoranditssystemshallbesoconstructedthatfailureofany componentwill not prevent the turbine from being safelyshutdown.

5.1.4 Ifthegoverning (control)system isoftheelectrohydraulictype,thentheelectronicequipmentadditionallyshallcomplywiththerequirementsspecifiedinannexA.

5.1.5 The governor and the steam valve operating device shall be sodesigned that the instantaneous loss of any load up to themaximum obtainable under rated conditions or the abnormal

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conditionsspecifiedin6.3.1shallnotleadtotransientoverspeedsufficienttocausetheturbinetotrip.

5.2 Speedandloadadjustments

Unlessotherwisestatedinthecontract,whenoperatingatzeroload,thespeedoftheturbineshallbeadjustableasfollows:

- when driving a generator ,within at least the range from 5%belowto5%aboveratedspeed;

- whendrivingamechanicalload,withintherangetobeagreed.

Themaximum time required for speed and load adjusting devices tochange the set point from zero to rated load at rated speed shall notnormallyexceed50seconds,butmaybeagreedbetweenpurchaserandsupplier.Meansshallbeprovidedforadjustmentofthesetpoints.

5.3 Governorcharacteristics

Thespeeddroopanddeadbandcharacteristicsrequiredformechanicalandelectrohydraulicgoverningsystemsareasrequiredbytable1.

Numerical values are given for guidance. Special consideration shallbegiventotheneedsof industrialturbinesandforturbinesforgeneratingpurposeswheretheratedoutputismorethan5%ofthesystemcapacity.

5.4 Valvetesting

For industrial type turbines,and for those turbineswhichhavea singlestop valve or governing valve, or where the governing valves areoperated by a single actuator,means shall be provided whereby theemergency and governing valves may be partially stroked to checkfreedomofmovement,withoutinterruptingoperationoftheturbine.

Forothertypesofturbine,thecontrolgearshallbeprovidedwithmeansoffullclosureonloadtestingofanyofthevalvesspecifiedin7.5inturn.

Thesuppliershallstatetheextentofanyoutputrestrictioninvolved.

5.5 Overspeedtrip(emergencygovernor)

5.5.1 Inadditiontothespeedgovernor,theturbineandgeneratorshallbe protected against excessive overspeed by a separatelyactuatedoverspeedprotectionsystemwhichoperatesthetrip.

Theoverspeed trip shalloperatenormallyata speedof10% inexcessof rated speed,witha toleranceof1%of rated speed ineachdirection(i.e.ataspeednotmorethan11%orlessthan9%inexcessofratedspeed).

Inexceptionalcircumstances(forexample,inordertoconformtothe requirements of 5.1.5), and by agreement, it may benecessarytoprovideanormaltripsettingabove10%(withthe1%tolerance above and below the selected figure). In any caseshould the speed governor fail in the event of a sudden loadrejection,theoverspeedtripshouldoperateataspeedwhich is

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sufficiently lowto limitthemaximumoverspeedtoasafevalue,i.e. topreventanydamage toanypartof the turbineordrivenmachinery;ortoanyelectricmotorswhichmayremainconnectedto thegenerator following load rejection,and to theequipmentwhich theydrive.Theoverspeed tripsettingsshallbestatedbythesupplierintheoperatinginstructions.

5.5.2 Forindustrialandothersmallturbines,anoverspeedtripsystemshallbeprovided, independentofthegovernor,theoperationofwhichshallclosetheemergencystopvalvesandgoverningvalves.

5.5.3 Forallothertypesofturbine,atleasttwoentirelyseparateoverspeedtripdevicesshallbeprovided,functionally independentofthegovernor,theoperationofeitherofwhichshallclosealltheemergencystopvalvesandgoverningvalves.

Itshallbepossible,whilethesetisinoperationatratedspeed,todemonstrate the correct functioning of each of the overspeedtrip devices while the set is protected by the second deviceagainstoverspeed,andwithoutaffectingthepositionofthemainsteamvalves.Meansshallbeprovidedso that,whenoneof theoverspeeddevicesisbeingtestedforcorrectfunctioning,itshallnot be possible to block or impede the second device fromoperationifcalledupon.

5.5.4 For industrial type turbines, theoverspeed trip system shallbecapableofbeingresetwithoutstoppingtheturbine.

5.5.5 Forallothertypesofturbine,theoverspeedtripmechanismshallbecapableofbeingresetwhentheturbinespeedhasdecreasedtoaspeednotlowerthantheratedspeed.

Table1GovernorDroopanddeadbandcharacteristics

Governortype Mechanical Electrohydraulic

TurbineMCR,MW Upto20 20to150 Over150 Upto20 20to150 Over150

Overalldroop,% 3to5

Incrementaldroop,%

a) range (0 to 0.9) xMCR

b) range(0.9to1.0)xMCR

Maximum=nolimitand

Minimum=0.4xoveralldroop

a) 3to8

b) Notgreaterthan12

Average incremental Notgreaterthan15 Notgreaterthan10

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droop over the range0.9MCRtoMCR**,%

Deadband,%ofratedspeed

0.40 0.20 0.10 0.15 0.10 0.06

** Fornozzlegoverned (controlled)turbinesemployingpartialarcadmission,theaveragevalueofdroopovertherange90%to100%oftheoutputcontrolledbyanynozzlegroupgoverningvalve,otherthanthelast,shallnotexceedthreetimestheoveralldroop.

6 OperationandMaintenance6.1 Normaloperation

6.1.1 Fornormaloperation, the characteristicsof the turbine shallbesuch that the turbineanddrivenmachinecanbe run inparallelwithanyexistingmachinesprovidedthelattercanruncorrectlyinparallelwitheachotherandpossessnoabnormalfeatureseitherindividuallyorcollectively.

6.1.2 Startups of superheat turbines can be classified into variouscategories according to the thermal condition of the turbine atthe time. The true ruling criteria are themetal temperature towhich the various components (such as HP inner casing) havecooled,but it is alsousual to classify the starts in termsof theelapsedtimeafterpreviousoperation;the featureswhich followgivetypicalcorrelations,andmaybetakenforguidance.

Typicalstartupcategoriesare:

a) Cold start, after a shutdownperiod exceeding 72hours(metal temperatures below approximately 40% of theirfullyloadvaluesinoC)

b) Warm start, after a shutdown period of between 10hours and 72 hours (metal temperatures betweenapproximately40%and80%oftheirfullyloadvaluesinoC)

c) Hotstart,afterashutdownperiodof lessthan10hours(metal temperatures below above approximately 80% oftheirfullyloadvaluesinoC)

d) Very hot restart, within 1 hour after a unit trip (metaltemperaturesatorneartheirfullloadvalues).

6.1.3 The purchaser shall specify the following duties for which theturbineshallbedesigned.

a) thenumberofstartsineachoftheabovecategoriesNote: In theabsenceof thepurchasersrequirements inthisrespect, thesuppliershallstatethenumberofeachtypeofstartforwhichtheturbineisdesigned.Aschedule,typicalofaturbineintendedforultimatetwoshiftoperation,mayinclude

- 100coldstarts

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- 700warmstarts

- 3000hotstarts

b) thenumberofmajorloadcycles

c) the rateof loadchange required foreachclassof significantloadcycle,takingintoaccountanylimitationsinotherpartsoftheplant,suchasthesteamgenerator.

Note:thepermittedrateofloadchange,andthesignificanceoftheloadcycle,arerelatedtothecharacteristicsofthesteamgenerator(see6.1.4)andtothemode of turbine operation during each load change (i.e. throttlegoverning(control) or nozzlegoverning (control), as well as to the particular turbinedesign.Rapidchangesofsteamtemperaturewithintheturbine,whichduringloadchangescandependonallofthreefactors,may leadtoundesirablyhighthermalstresses insomecomponents,andhenceexcessivereduction intheirlife.

In addition to the major load cycle defined, further minorvariationsfromstableconditions(i.e.incrementsoflessthan10%ofMCR)maybeaccepted,andtheseneednotbestated.

6.1.4 Thepurchasershallprovide,bona fide,thecharacteristicsofthesteam generator, to include the variation inpressure and initialand reheat temperatureswith steam flow rate, for all the startcategories,loadcyclesandshutdownregimesenvisaged.

6.1.5 Thepurchasershallspecifywhetheraturbinebypasssystemistobeemployedandifsoshallstateitsduties,steamconditionsandflowrates,andbywhomitshallbesupplied.

6.1.6 Thepurchasershallalsospecifytheparametersofsteamavailablefromauxiliarysources.

6.2 Limitsofvariationofratedconditions

The turbine shall be capable of accepting variations from the ratedconditionswithinthelimitsstatedbelow:

a) Initialpressure

Theaverageinitialpressureattheturbineinletoverany12monthsofoperation shall not exceed the rated pressure. Inmaintaining thisaverage, thepressure shallnotexceed105%of the ratedpressure.Furtheraccidentalswingsnotexceeding120%of theratedpressurearepermitted,provided that theaggregatedurationof such swingsoverany12monthsofoperationdoesnotexceed12hours(butseenoteattheendof6.2)

Note:Seedefinitionofratedsteamconditionsin3.3

Anincreaseininitialpressurenormallypermittheturbinetogeneratepower inexcessof itsnormal rating,unlessaction is taken throughthecontrolsystemtorestrictthesteamflowrate.Thegeneratorandassociated electrical equipment may be unable to accept suchadditionaloutput,andundesirablestressesmayalsobe imposedon

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the turbine; thepurchaser shallaccordinglyprovide loadresponsivemeanstolimittheturbineoutputundersuchcircumstances.

Thepurchasershallprovidemeanstoensurethattheturbineexhaustpressurebefore the reheater cannotexceed125%of the specifiedpressure at this point when the turbine is operating at its ratedoutput.

b) Initial,andwhereapplicable,reheattemperature

Forratedsteam temperatureup toand including566degreeC, thepermissiblevariationsareasstatedinthesucceedingparagraphs.Forrated temperatures in excess of 566 degree C, the permissiblevariationsshallbe thesubjectofagreementbetween thepurchaserandthesupplier.

Theaveragesteamtemperatureatany inlettotheturbineoverany12monthsofoperation shallnotexceed the rated temperature. Inmaintainingthisaverage,thetemperatureshallnotnormallyexceedthe rated temperature by more than 8K. if, exceptionally, thetemperature exceeds the rated temperature bymore than 8K, theinstantaneousvalueofthetemperaturemayvarybetweenthisfigureandavalueof14Kinexcessoftheratedtemperature,providedthatthe totaloperating timebetween these two limitsdoesnotexceed400 hours during any 12 months operating period. Operationbetween limits of 14K and 28K in excess of the rated temperaturemaybepermitted, forbrief swingsof 15minutesor less,providedthat the total operating time between these two limits does notexceed80hoursduringany12monthsoperatingperiod. Innocaseshallthetemperatureexceedtheratedtemperaturemorethan28K(seenoteattheendof6.2)

Should steam be supplied to any terminal point on the turbinethroughtwoormoreparallelpipes,thesteamtemperatureinanyofthesepipesshouldnotdiffer fromthat inanyothermorethan17K,exceptthatduringfluctuationsnotexceeding15minutesindurationwithinanyfourhourperiod,atemperaturedifferencenotexceeding28K shallbeadmissible.The steam temperature in thehottestpipeshallnotexceedthelimitsgivenintheprecedingparagraph.

c) Backpressureturbineexhaustpressure

Theaverageexhaustpressureshallnotexceedthespecifiedexhaustpressureoverany12monthsoperatingperiod.

Inmaintaining thisaverage, theexhaustabsolutepressure shallnotexceedtheratedpressurebymorethan10%ordropmorethan20%belowit.

d) Condensingturbineexhaustpressure

The turbine shall be capable of operating with any variation inexhaustarisingfromtherangeofcoolingwatertemperatureorflow

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specified,oralternativelytherangeofexhaustpressurespecified.Thesuppliershalldeclareanylimitationsintheserespects.

e) Speed

The turbine shall,unlessotherwiseagreed,be capableofoperatingwithoutrestrictionondurationoronoutputbetween98%and101%ofratedspeed.

Operationatspeeds furtherremoved fromratedspeedshallnotbepermittedexceptbyagreement.

Note: The limitations placed on variations of initial pressure and initialtemperaturein6.2a)and6.2b)respectivelyareappropriateforaturbinesuppliedwithsteamfromafossilfiredboilerorotherhightemperaturesource.

Foraturbinesuppliedwithsteamatornearsaturatedconditions,forexamplefromanuclearreactor,thelimitationstobeplacedoninitialsteamconditionsshallbeagreedbetweenthepurchaser,thereactorsupplierandtheturbinesupplier.

6.3 Abnormaloperation

6.3.1 The purchaser shall specify his requirements if operation isrequiredinanyofthefollowingcategories:

a) partofthecondensercoolingsectionisolated

b) someorallofthefeedwaterheatersoutofservice

c) overload,andhowitshallbeachieved

d) anyotheroperatingmodewhichimposesunusualconditions

6.3.2 The supplier shall state any limitations arising from specifiedabnormaloperation.Thismay includesuchmattersasstructuralloadingoradjustmentinoutputpower,andtheyshallincludethepermitteddurationforsuchlimitations.

6.4 Installationconditions

6.4.1 thepurchasershallspecifywhether the installation is indoorsoroutdoors,withorwithoutaroof,andtheconditionsinwhichtheturbine unit must operate, including maximum and minimumtemperatures, relative humidity, unusual dust problems,precipitation and wind speed (if outdoors), and other relatedfactors.

6.4.2 Thepurchasershallprovideanyrelevantdataconcerningseismicconditionsforwhichtheplantistobedesigned.

6.5 Maintenance

Whenrequestedbythepurchaser,thesuppliershallgiveinformationontheanticipatedfrequencyandscopeofmaintenancefortheturbineplant.

6.6 Operatinginstructions

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Thesuppliershallprovideoperatinginstructionswhollyrelevantandfreefromambiguity,whichwillenabletheplantwhichhehassuppliedtobeoperatedsafely.

The instructions shall include reference to all limitations on plantoperation, andmay also include the suppliers requirements for steampurity.

7 Components7.1 Materialsandconstruction

Allmaterials,components,andweldingused in theconstructionof themachine,andallpiping,mounting, fittingsandancillaryapparatusshall,so far as is reasonable, meet the requirements of the appropriatenational or international standards. The standards shall be specified inthecontract.

7.2 Partssubjecttohightemperatures

a) unstressedparts

The selection of material for parts not subjected to appreciablestresses at their operatingtemperature shall be such as to avoidunacceptabledeteriorationofpropertiesasaresultof;

i) Internalstructuralorconstitutionalchanges;or

ii)Reactionbetweenthematerialanditsenvironment

b) Stressedparts

Thematerialsused for stressedparts shall fulfil conditions statedundera)above.Inaddition,theyshouldbeselectedonthebasisofexperimentally determined data which confirm that under theconditions of stress, temperature and time in which thecomponentswillbeused,theywillnotcrackordeformtoagreaterextentthatispermissible.

7.3 Casingsandpedestals

Casings,pedestalsandsupportsshallbedesignedtowithstandallnormalandemergencyserviceloads,allowablepipingforcesandmoments,andmovementcausedbytemperature.Thecasingdesignshallbesuchthatthermal stresses in service are minimised. Turbine casings shall beadequatelysupportedtomaintaingoodalignmentwiththerotors.

Jackscrews, lifting lugs,eyebolts,guidedowelsandspecialtoolsshallbeprovidedwherenecessarytofacilitateassemblyanddismantling.

7.4 Rotors

7.4.1 Rotorswhencompletedshallbedynamicallybalanced.

7.4.2 The critical speeds of the combined turbine and the drivenmachine shall be sufficiently removed from the rated speed toavoid any adverse effect on the operation of the unit over the

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range of speeds from 6% below rated speed to that obtainedfollowinga full load rejectionwhen the speedgoverning systemfailstooperate.

Where the driven machine is not supplied by the turbinemanufacturer, agreement shall be reached as to the partyresponsible for the critical speeds of the combined turbine anddrivenmachine.

7.4.3 An overspeed test of each turbine rotor shall be carried out,preferablyatthemanufacturersworks.Theoverspeedtestshallbe at a speed exceeding by 2% themaximum calculated overspeed thatwould occur if the speed governor failed and if themaximum overspeed were limited by the action of the overspeed tripdeviceonly.Thedurationof theoverspeed testshallnotexceed10minute,anditshallonlybeperformedonce.

Whenthenormalsettingoftheoverspeedtrip isat10%excessspeed, theoverspeed test shallnotbe inexcessof20% aboveratedspeed.

7.4.4 Rotors and their couplings (and gearing where used) shall bedesigned to withstand those conditions imposed by generatorshortcircuits, or by other specified disturbances within theelectricalsystems.

The purchaser shall provide protection devices to reduce oreliminatetheeffectontheturbogeneratorofanyelectricalfaultonthesystem.

7.5 Valves

Theturbineshallbeprovidedwithanappropriatenumberofgoverning(control)valves.These shallbe suitable for controlling the initial steamsupplytotheturbineovertheentirespeedand loadrange. Inaddition,suitableemergency stop valve(s) shallbeprovided in serieswith thesegoverning valves. The valves which first receive steam shall each beprovidedwithasteamstrainerlocatedascloselyaspracticable,upstreamof the valve. For small industrial type turbines, the emergency andgoverning(control)functionsmaybecombinedintoasinglevalve.

On those turbines which operate with a reheat steam cycle, anappropriate number of reheat governing (control) valves shall beprovided. Suitable reheat emergency stop valves shall be provided inserieswith these governing (control) valves. The valveswhich receivesteamfirstfromthereheatshalleachbeprovidedwithasteamstrainerlocatedascloselyaspossibleupstream,exceptwhere;

a) thefirstvalve isoftheswingingflaptype(inwhichcasethestrainershallbeprovidedbetweenthefirstandsecondvalves),or

b) reheatiscarriedoutinasteam/steamreheater.

7.6 Mainbearingsandhousings

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a) Journalbearingsshallbetransverselysplitwithrenewableliner,padsorshells.

b) Thrust bearings shall be designed to accommodate thrust in eitheraxialdirection.Thethrustbearingshallhaveprovisionforadjustmentofrotoraxialpositionduringmaintenance.

c) Itshallbepracticable to renewall thebearingswithoutdismantlinganycylinder.

d) Journalandthrustbearingsshallbedesignedforpressurelubricationandtoensureproperdrainage.

e) Bearing housings shall provide protection against the ingress ofmoistureorforeignmatterandtheleakageoflubricant.

f) Tominimise the effectsof electrical currents generatedby electrostatic friction effects, the shafts of the turbine and the drivenmachineshallbeearthed(grounded).Incaseswherethesemachinesare suppliedby separate suppliers, thepurchaserand supplier shallagreetothelocationoftheshaftearthingpoints.

Forthesmallerindustrialturbines,earthingisnotusuallynecessary.

7.7 Cylinderandinterstageglands

Glandsattheendoftherotorandbetweenthestagesshallbeofsuitablematerialstominimisedistortionorgrowthattheoperatingtemperature.

The constructionof theglands shallbe suchas tominimisedamage totherotorintheeventofrubbingwhileinoperation.

7.8 Thermalinsulation

Whenspecified,theturbineshallbe insulated.Thepurchasershallstatethe required outer surface temperature of the insulationmaterial (notnormallyexceedingtheambienttemperaturebymorethan40K,but inaccordancewithnationalstandards).The insulationshallbesodesignedthatturbinemaintenanceisfacilitated.

Thepurchasershallstateanylimitationoninsulationmaterials.

8 FoundationandBuildingsThe turbine supplier shallprovide thepurchaserwith the relevant information(staticanddynamicloads,outlinedrawings,seatingdetailsforcesandmoments,permissible foundation deflections, thermal expansions, etc) at the interfacebetween his own design responsibility and that of the purchaser or hisfoundation designer, to enable design and construction of the total supportsystemtoproceed.

The turbine supplier shall ensure that the deflections, natural frequencies ofvibration,andotherpropertiesofpartsofthefoundationdesignedandsuppliedbyhimwillhavenoadverseeffectontheoperationoftheplantovertherangeofspeedsspecifiedin5.2and5.3.

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Details of loads transmitted to the turbine,when in service andwhen not inservice,includingallpipingforcesandmoments,shallbeagreedwiththeturbinesupplier.

Unlessagreedotherwise,thepurchasershallprovideasuitablefoundationblock,onwhichtheturbinesuppliershallbegiventheopportunitytocommentatthedesignstage.Thenaturalfrequenciesofvibrationofthefoundationshouldnotcorrespondtoanylowmultipleoftheoperatingspeedoftheunit.

Sufficient space and necessary openings in the foundations and buildingstructureshallbeprovided for installationoftheequipment.Suitableopeningsshallbeprovided in thebuilding toadmit theequipment.Thepurchaser shallprovidesufficientspacearoundtheequipmentforservicing,includingspaceforremovingtherotorsandsettingdowntheupperhalvesoftheturbinecasings.

Where ancillary equipment connected to the turbine (for example,moistureseparators and reheaters) ismounted on a separate foundation supplied byothers, the turbine supplier shall specify thepermissiblemovement relative totheturbinefoundation.

9 FeedPumpDrivesFeed pumpsmay be driven by a variety ofmeans,which can differ in theirthermodynamic influenceonthecycle.Theturbinesupplierwillusuallyrequireinformation,as listedbelow,beforedesigndetailsorthedeterminationofheatratecanbefinalised.

9.1.1.Drivebyauxiliaryturbine

Where thepump isdrivenby an auxiliary turbineusing steamextractedfromthemainturbine,orwhereexhauststeamfromtheauxiliaryturbinedischargesintothemainturbineoritssystem:

i) when the main turbine supplier supplies the feed pump and itsdriving turbine, thepurchaser shall, at anyearly stage,provide theturbine supplierwith information showing the required feedwaterpumpgeneratedheadasafunctionoffeedwaterflowrate;

ii) whenthemainturbinesuppliersuppliestheseparateturbinedrivingthefeedpump,butdoesnotsupplythepump,thepurchasershall,atanearlystage,providetheturbinesupplierwithinformationshowingthevariationoftherequiredpump inputpowerandspeedandfeedpumpgeneratedhead,asfunctionoffeedwaterflowrate;

iii) whenthemainturbinesuppliersuppliesneithertheseparateturbinedrivingfeedpump,northepump,thesuppliershall,atanearlystage,providetothemainturbinesuppliersufficient informationtoenablethefeedwaterenthalpyriseacrossthepumpandthesteamflowtotheseparateturbinetobederived,overtherangeoffeedwaterflowrate.

Ini)andii)above,thisinformationshallcovertherangefromtheminimumloadon themain turbineatwhich the turbinedriven feedpump is tobe

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independentlycapableofmeeting the feed flow requirements,up to themaximumfeedwaterflowrateforwhichthepumpanditsdriveraretobedesigned.

An additionalmargin of power and speed, above that required for themaximumpowerrating,shallbeallowedbefore fixingthecapacityoftheauxiliary turbine; theamountof thismarginshallbeagreedbetween thepurchaserandthemainturbinesupplier.

If the main turbine supplier does not supply interconnecting pipingconveyingsteam from thesupplypointon themain turbine,or from themainsteampipes (or fromothersources), to the feedpump turbine, thepurchaser shall state to the main turbine supplier the drops in steampressureandtemperaturetobeallowedinthispiping.

9.1.2Drivebyelectricalmotor

Where the pump is driven by an electrical motor, sometimes directly,sometimes through a speedchanging gear, and sometimes through aninterposedhydrauliccoupling.

i) When the turbine supplier supplies thewhole of this equipment,thepurchasershall,atanearlystage,providetheturbinesupplierwith information showing the required feed pump head againstfeedwaterflowrate.

ii) Whentheturbinesuppliersuppliesthedrivingequipment,butnotthepump,thepurchasershall,atanearlystage,providetheturbinesupplier with information showing the required pump power(measured at the inletpump coupling) and feedpump generatedhead as a function of feed water flow rate and also the pumpmaximumspeed.

iii) Whentheturbinesupplierdoesnotsupplythefeedpump,motor,speedchanginggearorhydraulic coupling, thepurchaser shall,atan early stage, provide the turbine supplier with informationshowing theenthalpy rise in the feedwaterasa functionof feedwaterflowrate.

9.1.3Marginonpumpduty

In all instances, the specified feed pump flow rate shall includeattemperationwaterrequirementsforsuperheater,reheater,andturbinebypass,wherethereareprovided.

9.2General

9.2.1Wherethefeedpumpisdrivenbyanauxiliaryturbine,theauxiliaryturbinesupplier and the pump supplier shall agree all the relevant interfaceinformation, including the direction of rotation. Consideration shall begiven to the supplyarrangements for lubricatingoil,control fluid, sealingwater to the feed pump and gland sealing steam to its driving turbine,bearing inmind that thesemayneed tobe separated from thoseof the

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main turbine. The requirement for fitting turning gear shall be agreedbetweentheauxiliaryturbineandfeedpumpsuppliers.

9.2.2 Consideration shall be given to any requirement for preventing orrestrictingreverserotationofthefeedpump.

10 TurbineAuxiliarySystems10.1 Lubricatingoil

The turbineshallhaveamainpumpwhichshallbedrivenmechanicallybytheturbineitselfor(byagreement)byanelectricalmotor.

An auxiliaryoilpump,driven from a sourceentirely separate from themainoilpump,shallbeprovidedtooperatewhenstartinguporshuttingdown the turbine, and to come into operation automatically as areplacementtothemainpumpintheeventoflowoilpressure,toenabletheturbinetoremaininservice.Provisionshallbemadeonloadtesttheauto start of all backup lubricating oil pumps by simulating low oilpressure.

Anemergencystandbypump,preferableDCmotordriven,ofadequatesize to permit a safe rundown of the set, shall be provided to startautomaticallyintheeventofthefailureofanauxiliaryoilpumporofitselectrical supply;alternatively,byagreement,agravityoil tankmaybeprovidedforthispurpose.

Ajackingoilsystemshallbeprovidedtosupplyhighpressureoiltoeachturbine and generatorbearing, if this isnecessary, to lift the rotors toreducestartingtorqueandbearingwearwhenbarring(turning)orduringstarting.

Multipleoilcoolersandfiltersshallbeprovidedofsufficientcapacitysothatanyoneoilcoolerorfiltercanbetakenoutofservicewiththesetinoperation.Theinletandoutletchangeovervalvestothecoolersorfiltersshallbearrangedsothattheyarenotcapableofshuttingofftheflowofoil to the bearings while the set is in operation. For industrial typeturbines,singleoilcoolersandfiltersmaybeprovided.

Allpipes,valves,coolerbodiesandfiltersbodiesshallbeofsteelorotherappropriate material. Brittle materials such as cast grey iron are notsuitable.Pipejointsshallbeweldedwheneverpracticable.

Precautionsshallbetakentominimiseinternalcorrosioninoiltanksanddrainpipes.

Thesuppliershallspecifythepropertiesofthelubricatingoiltobeused.When initialflushing isnotcarriedoutbythesupplier,theoilusedshallbetohisapproval.

The design of the lubricating system shall be such that during normaloperation, the operating temperature of the oil at eachmain bearingdrainwillnot, ingeneral,exceed75degreeC.Thereareapplicationson

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smallturbineswherethistemperaturemaybeincreasedto85degreeC.Precautionsshallbetakenagainstfirecausedbyleakageoflubricatingoil.

10.2 Controlfluid

Thefluidusedinthecontrolsystemandforoperationofthesteamvalvesmay be either oil from lubricating system, or fluid from an entirelyseparatesystem.Thepumpssupplyingtheseparatecontrolfluidshallbeduplicated,withautomaticchangeoveronfailureofonepump.

Arrangementsshallbemade,ifnecessary,tosustainthepressureofthecontrolfluidduringthestartingperiodofthestandbypump.

When the fluid other than oil from the lubricating system is used, thefluidshallbetothesuppliersapproval.Thesamerequirementsregardingmaterials,pipeconstructionandtheduplicationofthecoolersandfiltersasin10.1shallbeapplyunlessotherwiseagreed.

10.3 Sealingsystemformotorandvalveglands

Thesealingsystemattheendsoftherotorsandvalveglandsshall,unlessotherwiseagreed,besoarranged,byexamplebytheprovisionofaglandsteam condenser that no steam issues into the turbine hall. Whereappropriate, the control of sealing steam for the glands shall be fullyautomaticunderallmodesofoperation.Reliefvalves shallbe fitted tothesteampipeworkasnecessary.Whentheauxiliarysteamisrequired,suchasforstartup,thesuppliershallstatehisrequirementforthesteamconditionsandquantity.

10.4 Drains

Eachturbinecasing,steamchest,orothervessel,andallpipesconveyingsteam, including bled steam pipes to feed water heaters, shall beadequatelydrainedatallpointswherewatermayaccumulate.

Drainageshallnormallybetoasuitabledrainsvessel,andallpipesshallincorporatesuitablevalves,traps,ororificeplatesbeforedischarge intothedrainvessel.

10.5 Vents

Ventpiping shallbeprovided from the gland steamexhauster fan andlubricatingsystemexhausterfan(s)toaspecifiedoutdoorlocation,orasagreed.

10.6 Turninggear

Turninggear (barringgear)shallbeprovidedtorotatetherotorsystemslowly (continuously or intermittently), if necessary, to limit thermaldistortionoftherotor(s)whennotturningundersteam. Interlocksshallbeprovided,ifnecessary,toensurethatturningcannotcommenceuntilan adequate supply of lubricating oil is available and the drive is fullyengaged. The turning gear shall disengage automatically when theturbinespeedincreasesabovetheturninggearspeed.

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10.7 Piping

All piping for steam,water, oil or air services shall preferably in steelcomplying with the requirements of the appropriate international ornationalstandards.Thestandardsshouldbestatedinthecontract.

Welded joints shallbeusedwhereverpracticable.Othermaterialsmaybeusedbyagreementbetweenthepurchaserandtheturbinesupplier.

The turbine supplier shall state the magnitude and direction ofapplicationofthepipeworkforcesandmoments,appliedattheagreedmajor terminatingpointsofhisequipment,whichareacceptable tohisplant.

11 Instrumentation11.1 General

Suchinstrumentsshallbeprovidedasarenecessarytoenabletheturbinetobereliablyandefficientlyoperatedandsupervised.

The scopeof instrumentation that iseconomically justifiedwilldependon the rating of the turbine and the conditions under which it is tooperate.Thefollowingrequirementsapplytolargeturbines.

11.2 Standardinstruments

Whereapplicable,primarymeasuringelementsforatleastthefollowingshallbeprovided.

a) Pressures

- Initial and reheat steam inlets immediately upstream of theinitialandreheatstopvalvesandstrainers;

- Extraction(s),forextractionturbines;

- Extractionstofeedwaterheaters;

- Exhaustsfromeachcylinder;

- Lubricatingoilsupplytobearings;

- Fluidsupplytothecontrolsystem.

b)Temperatures

- initialandreheatsteam

- steamatexhaustfromhighpressureandintermediatepressurecylinders;

- extractionstofeedwaterheaters;

- oilatcooleroutlet;

- oilinthebearingdrains,orbearingmetal.

c)Levels

- levelofoilinmainlubricatingoiltank;

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- leveloffluidincontrolfluidtank.

11.3 Supervisoryequipment

Equipmentformeasuringthefollowingshallbeprovided:

a) Speed:rotationalspeedoftheturbine;

b) Load: electrical output of the generator (frequently thisinstrumentisnotincludedintheturbinecontract);

c) Rotor and pedestal movement: axial differential movement ofselectedrotors,eachrelativetoitscasingorpedestal,measuredattheendremotefromthethrustbearing.

Axialmovementofpedestalsrelativetothefoundation;

d) Vibration: vibration of pedestals or rotors. Rotor eccentricity,andthephaseangleofthevibration,mayalsoberequired;

e) Metal temperatures: provision shall be made for themeasurement of allmetal temperature difference considerednecessaryforthesafeoperationoftheturbine,orforenablingstresses in turbine casing walls or other components to beassessed,toprovideinformationonsaferatesofrunuporloadchange;

f) Valveposition:positionsof all initial and reheat steam valves,unless otherwise agreed, except that only fullyopen or fullyclosedindicationisrequiredforreheatemergencyvalves;

g) For saturated steam turbines, which incorporate moistureseparators and reheaters; reheating steam flow (or reheaterdrainsflow),andlevelsinseparatorandreheaterdraintanks;

h) Inaddition,equipmentnecessarytoprovidethealarmandtripinitiatingsignalslistedinclause12shallbeprovided.

11.4 Additionalequipments

Additional primary measuring elements may be specified by thepurchaser,orrecommendedbythesupplier.

Forlargeturbineplanttheinstrumentationmaytypicallyinclude:

- coolingwatertemperature;

- condenserpressure;

- pressureandliquidlevelsinvariousvessels;

- steamandwatertemperaturesaninletandoutletoffeedwaterheatersandotherheatexchangers;

- inletandoutletpressureoffeedpumps;

- condensate,feedwaterandinitialsteamflowrates.Note:Primarymeasuringelementsforsuchmeasurementsmaybesuppliedbyothers.

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11.5 Testmeasuringpoints

Forthepurposeofcarryingoutperformancetestsforheatrateorotherreasons,measuring points shall be provided for all testmeasurementsand observations. Thesemeasuring points shall be additional to thoserequiredforthenormaloperationandcontroloftheturbine,andshallbeagreedbetweensupplierandpurchaser.

Agreement shall be reached upon responsibility for, and provision of,those required measuring points located at positions outside thecontractualscopeofsupply.

12 Protection12.1 General

The extent of protectionwhich can be economically justified dependsupontheratingoftheturbineandtheconditionsunderwhich ithastooperate.Thefollowingrequirementsapplytolargeturbines.

12.2 Protectionsystemtripping

12.2.1 A separate and independent turbine protection system shall beprovided.Thissystemshallbesodesignedthat intheeventofatrip signal occurring, its operation shall result in the immediateclosureofallsteamvalves(i.e.emergencystopvalves,governing(control) valves, reheat emergency valves, reheat governing(control) valves), and in the power closing of the nonreturn(check)valves (wheretheseare fitted) inthecoldreheatsteampipes, inthebledsteam linestothefeedwaterheaters, inothersystemsnormallysuppliedwithsteam fromtheturbine;therebyenabling the turbine to run down safely in the event of anaccidentwhich couldotherwise causedamage to the turbineoritsauxiliaryequipment.

12.2.2 The protection equipment shall be designed on a failsafeprinciple, such that loss of control fluid pressure shall causeimmediate closure of the emergency stop valves and thegoverning(control)valves.

12.2.3 Removalof thecondition thathas initiated theoperationof thetripsystemshallnotcausethetripgeartoresetautomatically,orthesteamvalvestoreopen.Thetripsystemshallbearrangedsothatitcanberesetonlybytheoperator.Untilthetripsystemhasbeen reset, it shall be impossible to reopen any of the steamvalves.

12.2.4 Tripsystemshallbebasedon,butnotnecessarilyconfinedto,thefollowing listof initiatingdevices,operationofanyoneofwhichshallcauseoperationofthetripsystem:

a) overspeedtrip(see5.5)

b) manualtriplocaltotheturbine

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c) emergencystoppushbutton,locallyandremotelyoperated

d) highexhaustpressuretripNote: Increase in condenserpressureabovea set value shallbearranged to

actuateone(ormore)alarms,whichmaybesetatdifferentpressures.Furtherincreaseincondenserpressureshallresultinaunittrip.

e) lowsteaminletpressuretrip(whererequired)

f) lowlubricatingoilpressuretrip

g) lossofspeedgovernortrip(forelectricgovernors)

h) trip initiated by the generator or its auxiliary system: forexamplelossofgeneratorstatorwindingcoolingwater

i) electricallyoperated trip automatically initiated by electricalfaultoperation

12.3 Protectionsystemalarms

Alarms shall be raised, but the turbine shall not (unless otherwisespecified)betrippedfor

a) excessivethrustbearingwear

b) highsteamtemperatureatthelowpressurecylinderexhaust

c) excessivebearingtemperature(oilormetal)

d) excessivevibration

12.4 Protectionsystemotherdevices

Otherprotectiondevices,whichshallnot,unlessspecifiedinthecontract,initiatetrippingoftheturbineshallbeprovided.Theseinclude

12.4.1 Lowpressurecasingandcondenserpressurisation

The low pressure cylinder and the condenser shall be protectedagainstexcessivepressurebyvalvesorreliefdiaphragmsofsufficientsizetokeepthepressurewithinpermittedlimits.

12.4.2 Wateringressfromfeedwaterheatingsystem

Protection againstwater entering the turbine from the feedwaterheatingplantshallbespecifiedbythepurchasertothesupplierofthefeedwaterheatingplant.Themainfeaturesofsuchprotectionshallincludeatleast;

a) Eachbledsteamlinefromtheturbineshallbearrangedsothatalltheheater surfacemust be flooded before anywater can flow to theturbine. The heaters should preferably be located lower than theturbine.

b) Forevery feedwaterheater,thereshallbetwo independentmeansofautomaticallypreventingwaterfromenteringtheturbinefromtheextraction system; the system shall be designed so that no singlefailureofequipmentresultsinwaterenteringtheturbine.

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Ingeneral,these independentmeanscanbeacombinationeitherofthefollowingitems;

2)andeither1)i)or1)ii),

Or 3)andeither1)i)or1)ii),

Or 2)and3).

1) i)Provisionofgravitydrainagefromtheheater,withopenmanometricseal,or

ii)Provisionofanautomaticalternativedrainageroute,oflargecapacityfromtheheater.

Note:1)i)istobepreferredto1)ii),ifconditionspermititsuse.

2)Provisionofautomatic isolatingvalves in thebledsteam linesbetweentheturbineandthefeedwaterheater,and indrainlinescascadingintotheheater.

3)Provisionofautomatic isolating valves forall sourcesof feedwater to theheater.Thiswillnormally requireanautomaticbypassaroundtheheater.

NoteThetimesofoperationofeachoftheautomaticisolatingvalvesrequiredby2)and3)above,fromreceiptofclosingsignaltothefullyclosedpositionshouldbesuchthatforwaterflowsintotheshellequivalenttothelargeof;

a) waterflowingfromtworupturedtubes(fromtubeends),or

b) water flow equivalent to 10% of theheater tube side flow atMCR, thevalves should be closed before the water has filled the usable storagevolume between the high level alarm (which initiates the valve closure)andtheautomaticisolatingvalve.

Items1) ii),2)and3)shallnormallybe initiatedbyhighwater levelsensors in the heater shell, with suitable precautions to ensurereliableoperation.

c) Nonreturn (check) valves, normally provided in extraction lines tolimitspeedriseonlossofload(see19.3),shouldbelocatedascloselyaspracticabletotheturbineextractionpoints.

Isolatingvalvesandpowerclosednonreturnvalves,whereprovided,shall be arranged for testing (by closing) while the plant is inoperation.

Powerassistedandfreeswingingnonreturnvalvesshallbearrangedforcheckingforfreedomwhiletheplantisinoperation.

d) Wheremorethanonebankofheaters issuppliedfromasinglebledsteam line, either each heater shall have its own valves, or if thevalvesareinthecommonline,waterfromafloodingheatershallflowinto the isolatedheaterandcompletely flood itbefore it ispossibleforwatertofloodthecommonbledsteampipeuptotheturbine.

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e) Eachheatershallbeprovidedwithhighwaterleveldetectorswitches,induplicateandeacharrangedfortestingforcorrectoperationwhilethe plant is in operation. Operation of such switches shall initiateoperationoftheprotectivedevices.

12.4.3 Moistureseparatorandreheateroverpressure

The vessels containing themoisture separatorsand reheaters shallbe protected against overpressurisation by suitable relief valves,burstingdiaphragmsorotheragreedmeans.

12.4.4 Lowsteaminletpressureunloader(ifrequired)

Reduction in inlet steampressure to the turbinebelow a set valueshallbearrangedtoclosethegoverningvalvesandsotoreducetheturbine loadprogressivelydowntoanagreed lowvalue.Restorationofsteaminletpressureshallnotresultautomaticallyinreopeningofthegoverningvalves,unlessotherwiseagreed.

Forfurtherreduction insteam inletpressureshallresult inaturbinetrip(see12.2.4)

Note: where it is intended that the turbine should operate at partial load, atcontrolled, reduced, initial steampressure, theprotectivedevicesof thelowsteam inletpressureunloaderand the lowsteam inletpressure trip(see12.2.4) shouldbe soarrangedas tocontinue toprotect the turbineagainst a rapid decrease in inlet pressure, but automatic reopening ofgoverningvalvesduringnormaloperationispermitted.

12.4.5 Unwantedsteam

Protectionagainstunwantedsteamadmission to theexhaustof thehighpressureturbineisnecessaryifaturbinebypassisused.

This isnormallyachievedbytheprovisionofat leastonenonreturn(check)valve.

13 Vibration13.1Generalvibrationofpartsoftheturbine

Theturbineshallbearrangedtopermitvibrationmeasurementsinserviceat or adjacent to each main bearing (see 11.3 d); vibration may bemeasuredonthebearinghousing,ontheshaft,orrelativelybetweentheshaftandbearinghousing.Thispartdoesnotspecifylimitsforvibration.

The preferred criterion for the description of turbine bearing housingvibrationisthevibrationvelocity;thisis,forsynchronousvibration,relatedtothepeaktopeakdisplacementbytheformula;

2A=450v/f

Where,2Aisthepeaktopeakdisplacementinmicron(m),Visther.m.s.vibrationvelocityinmm/sandfistherotationalfrequencyinHz.

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Thepreferredcriterionforthedescriptionoftheshaftvibrationvelocityisthepeaktopeakshaftdisplacement.

13.2Vibrationmeasuredatthebearinghousing

Valuesofvibrationvelocity,measured ina radialdirectionat thebearinghousing,of2.8mm/sorbetter,areusuallyobtainableforturbinesingoodbalance, running under steady conditions at their specified operatingspeeds, but itmay be possible for a turbine to continue in satisfactoryoperationathighervalues.

Peaktopeakdisplacementscorrespondingtothisfigure(whichisinaccordwithQualityBandAofclassIVinISO2372)aregivenintable2.

Table2

Ratedturbinespeed(Hz)

Peaktopeakdisplacementmeasuredatthebearing

housing(m)

16.67 75

25 50

30 42

50 25

60 21

100 12

200 6

Note:Thedisplacementattheotherspeedscanbederivedfromtherelationship;

SpeedxDisplacement=1250(intheunitsquoted)

13.3Vibrationmeasuredattheshaft

Shaftvibration isusuallymeasuredrelativetothebearinghousing; Inanycase, thevibrationmeasurementsshallbecarriedout inaccordancewithISO 79191. vibrationmeasured on the shaft is likely to be considerablygrater ( by a factor of 2 ormore) than thatmeasured at the bearinghousing,dependingonthenodalpatternoftheshaft,theaxialpositionofthepickup,thebearingdesignandotherfactors.

14 Noise14.1Noiseemittedbytheindividualplantcomponents

Thenoiseof themachinery ismeasuredonan imaginary surfacearoundthemachine,at1.0mfromthemachinesurfaceandataheightof1.2mabove the level of the floor, walkway, or other position provided forpersonnelaccess.

The surfacenoise level isdefinedas themaximum Aweighted r.m.s.sound pressure level,measured on the slow response of a sound level

32

metercomplyingwith IEC651,type1,withthemicrophonepositionedasdescribedabove.

14.2Noiselevelinthevicinityoftheturbineunit

Thenoiselevelinthevicinityofthesteamturbineunitdependsuponmanyfactors such as the noise power generated by the various turbinecomponents,thenoisepowergeneratedbythecomponentsofotherplantin the station, the relative location of the turbine and the other plantcomponents, and the acoustics of the surrounding area and building,includingtheamountofsoundattenuatingmaterialpresent.

Whenalloftheabovefactorsarewithintheturbinesuppliersscope,thepurchasermaystatetotheturbinesupplierhisrequirementsregardingthepermissiblenoise level inthevicinityoftheturbine.Whenthefactorsarenot allwithin the turbine suppliers scope, itmay be necessary for thepurchaser,theturbinesupplier,andthoseresponsiblefortheotherfactors,to cooperate tomeet the purchasers requirements. Suppliers of othercomponents or plant in the vicinity of the turbine shall themselves beresponsibleforthenoiseitproduces.

If these requirementsarenotmetby thebasicdesignof theplant, theymaybeachievedbythesupplyofsuitableacousticscreensorenclosures.

15 Tests15.1 General

All the tests requiredby thispartshallbecarriedout inaccordancewiththestatedprovisions.

Any further tests required by the purchaser, and the extent of anywitnessing by the purchaser or his representative, shall be stated in thepurchasersspecification.

15.2 Hydraulictests

As part of theQuality Assurance Program, all parts subjected in normalservice to a pressure above atmospheric shall be tested hydraulically sothatthepressureloadsshallbeatleast50%inexcessofthemaximumthatcouldoccuratany loadwithratedterminalconditions(asdefined in3.3).The hydraulic test may by agreement, be omitted where, in service,leakage would not be to atmosphere. The hydraulic test may also beomittedbyagreementwhenthemanufacturercan,byothermeans,satisfythepurchaseroftheintegrityandsuitabilityofthecomponent.

15.3 Performancetests

The extent of any performance tests required shall be stated in thepurchasers specification, together with the extent of the suppliersexpectedparticipation.

ThermalacceptancetestsshallbecarriedoutinaccordancewithIEC9531orIEC9532.

33

SpeedandloadgoverningteatsshallbecarriedoutinaccordancewithIEC1064.

15.4 Testresultsanddata

The supplier shall make available to the purchaser such certificates orreports asmay be necessary to confirm that the objectives of all testsspecifiedinthecontracthavebeenachieved.

16 DeliveryandInstallation16.1Transporttositeandtemporaryprotection

Before shipping from theworks,all turbinecomponents shallbe suitablyprotectedagainstcorrosion,stresscorrosionandhandlingdamageduringtransportation to siteandany storageperiodbefore installation.Storageconditions and duration shall be specified and agreed between thepurchaserandthesupplier

16.2Erectionandcommissioning

The erection and commissioning procedures shall be in accordancewithrecommendations and instructions issued by the supplier either ondrawingsorbyothermeans. It is recommended thatwhereerectionandcommissioningdonotformpartofthecontract,thepurchasershould,asaminimum,usetheservicesofthesupplierssupervisor.

17 DesignInformationtobeSuppliedbythePurchaser17.1 General

The purchaser will normally provide a detailed specification of hisrequirementstothesupplier.Itisrecommendedthattherequirementsorotherrelevantinformationincludeatleastthoselistedbelow.

17.2 Characteristicsoftheturbineanditsaccessories

a) Rated output as defined in 3.5 at generator terminals or at theturbinecoupling.

b) Weighingfactorsforthermalperformanceguaranteepurposes,whenrequiredinpursuanceoftherequirementof4.2.

c) Speedofrotation,orsystemfrequency,andoperationalspeedrangerequired.

d) Thetotalrequiredrunninghours.

e) Detailsofturbinelocationandanyphysicallimitations.

f) Anyseismicconditionstobetakenintoaccount.

17.3 Steamandwaterconditions

a) Ratedsteamconditionsattheinlettoeachsetofturbinestopvalvesattheratedoutputandmaximumsteamconditions.

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b) Steampressure ateachexhaust flangeof the steam turbine at theratedoutput.

Note: This includes thepressureat the turbineexhaust flangewhen the turbinesupplierdoesnotsupplythecondenser.Whentheturbinesupplieralsosuppliesthecondenser,theinformationrequiredisasin17.4.

c) For a fossilfired plant, if the turbine is arranged for reheatingbetween cylinders, the reheater in not supplied by the turbinesupplier:

- thecoldreheatpressure(s);

- thepressuredrop(s)inthereheater(s),and

- thesetpressure(s)forsafetyvalvesonthereheatsystem(s).

d) If the turbine is provided with an external water separator, notsuppliedbytheturbinesupplier;

- thepressuredropinthesteam

- theefficiencyofwaterseparation

- thedestinationoftheseparatordrains

- the set pressure of the safety valves or other devices (see12.4.3),iftheyarenotwithintheturbinesuppliersscope.

If awater separator is followed by either singlestage ormultistage steam/steam reheaters, not supplied by the turbinesupplier;

- Thepressuredropinthereheatedsteam

- Thepressuredropinthereheatingsteampipe(s)

- Theterminaltemperaturedifferenceofeachreheaterstage

- Thedestinationofthereheaterdrains

Whereappropriate,theseparametersshallbedefinedasafunctionofsteamflowrate.

e) Ifwaterininjectedfortemperaturecontrolofeitherinitialorreheatsteam.

- the sourceof supply, the rateof flowand theenthalpyof thewater.

f) Ifmakeupwater istobesuppliedtothecondenserforpurgingandboilerlosses

- qualityandtemperatureofthewater.

g) If steam is required to be extracted for heating or other auxiliarypurposes;

- the flow rates and pressures required, the destination adenthalpiesof thedrains,whether theextractionpressure is to

35

be controlled, and whether account is to be taken of suchextractionsintheguarantees.

h) Forlowpressuresteamsuppliedtoamixedpressuresteamturbines;

- pressure

- meantemperature(ordrynessfraction)andrange

- steamflowrate

- methodofcontrolofsteaminput

- maximumpoweroutputrequiredwithhighpressuresteamonly.Note: The suppliermay require that the highpressure steam flowdoes not fallbelowavaluewhichhewillsupply.

i) Availability and conditions of steam from auxiliary sources, forexampleforglandsealingatstartup.

j) Thechemicalcharacteristicsofthesteamsupply.

k) Forboilerfeedpumps,thepurchasershouldprovidetheinformationlisted in clause9, togetherwith allother informationnecessary forthe thermodynamicandmechanical integrationof theplant.Wherepossible, the information should provide details of the vibration oftheseparameterswithfeedwaterrateorturbineoutput.

Note: In items c), d), e) and g) above, some exchange of information will berequiredbetween thepurchaserand the supplier, since the finaldesignofequipment not in the suppliers scope will be affected by the pressuredistributioninthefinalturbinedesign.

17.4 Conditions for condensers and coolers (where this equipment is in thesuppliersextentofsupply)

a) source of supply and quality of coolingmedium, or heat exchangesurfacematerialtobeused,andcleanlinessfactortobeusedinthedesign.

b) maximumandminimumtemperatureofthecoolingmedium,andtheaveragetemperatureovertheannualperiod.

c) any limitation on quantity of cooling medium available, or onpermissibletemperaturerise.

d) maximumandminimumpressureatterminalpointsofcoolingwatersystemandpressuredropbetweenthem.

17.5 Applications:installationandmodeofoperation

a) Particulars of the driven machine (if not supplied by the turbinesupplier)

- nameandmanufacturer

- complete dimensions of outline, interface, and holdingdownarrangements

36

- fullstatementofrelevantcharacteristics,includingallnormalorabnormal torques absorbed, and any axial thrust or journalbearingloadstobeabsorbedbytheturbine

- requirements for auxiliary services such as lubricating oil andcoolingwater

- if themachine isdriven through a gearbox, the speedof theoutputshaft

- anyrequirementsregardingbalancing,alignment,provision forexpansion, or othermatters which can influence satisfactoryoperationoftheassembledunit

Note:Thedirectionofrotationshallbeagreedwiththeturbinesupplier.

b) Thenatureofthe loadtobecarriedbytheturbine,andtheexpectedpatternandmodeofoperation.

c) The number, nature, and intensity of disturbances of the electricalsystemgivingrisetoabnormaltorques.

Themanufacturerofthegenerator, ifnotsameasthesupplieroftheturbine, shallprovide to the turbine supplierdetailsof the abnormaltorques thereby imposed on the turbine; determination of theseabnormal torquesmay require collaboration between the generatorandturbinemanufacturers.

d) Therelevantfactorsaffectingtheoperationoftheturbineforexample;

1) operationduty(see6.1.3)

2) adoptionofslidingpressure(see3.10)

3) maximumrequiredrateofloadpickup(see6.1.3c)

4) temporaryabnormaloperationconditions(see6.3.1)

5) characteristicsofthesteamgenerator(see6.1.4)

6) capacityofturbinebypasssystem,ifutilised(see6.1.5)

e) The relevant factorsaffecting theeconomicoptimisationof theplant.Theseincludethepurchasersevaluationfigurestoenableoptimisationoftheturbineitselfandofitscondensingplanttobecarriedout.

For fixed initial steam conditionsand steam flow rate,output canbeincreased and heat rate reduced, by judicious selection of variousturbineplantparameters,includingthoserelatingtothecondenseranditscoolingwatersystem.

Thepurchasershouldstatethefiguresinhisevaluationfor;

- thebenefit tohimandoneunit improvement inguaranteedheatrate

- the cost to him of one additional kilowatt of auxiliary electricalpowernotalreadyallowedforintheheatrateguarantee

37

- the incremental cost to him of one unit of volumetric flow ofcoolingwaterandofmakeupwater

- anyotherplantcharacteristicsordimensionswhichhewilltakeintoaccount.

f) Proposed control system defining those functions (e.g. starting andsynchronising, loading, shutdown, etc) which are to be carried outmanuallyfromlocalorremotecontrolpositionsandthosetobecarriedoutautomatically)

g) The information listed in A.6 (annex A) if an electronic governor isrequired.

h) Installationconditions(see6.4).

i) Thermalinsulationrequirements(see7.8)

j) Permissiblenoiselevel(seeclause14)

k) Additionalinstrumentationrequired(see1.4)

l) Whetherlowsteaminletpressureunloader(see12.4.4)isrequired.

17.6 Foundations

Ifthepurchaser isresponsible fordesignofthe foundation,heshallsupplythe turbine supplier at an early date with an outline drawing of thefoundationbasedoninformationprovidedbythesupplierinclause8.

17.7 Terminalpoints

Terminalpointsoftheplanttobesupplied.

17.8 Deliverysiteconditions

a) Pointofdelivery

b) Conditionsaffectingtransportandaccesstosite,facilitiesavailableonsite,andanyrequirementsforextendedperiodsofstorage.

17.9 Tests

Extentofperformancetesting(see15.3)

18 DesigninformationtobeprovidedbythesupplierThesuppliershallprovidedetailedinformationofhisplanttothepurchaser.Itisrecommendedthatatleastthefollowingitemsareincluded.

18.1 Forstabilityoftheturbineandforthemechanicaldesignoftheterminalpoints and pipework systems, the forces and moments from theprincipal steam pipes have to be limited. The supplier shall furnishadequate information to allow the purchaser to design the pipeworksystemsinaccordancewiththeserequirements.

Similar informationmayberequired inrespectofthefeedwaterpipingwhere the feedwaterheatersor similarplantarewithin the suppliersscope.

38

18.2 For the relevant operating conditions, the thermal expansion of theterminalpoints.

18.3 For all pipe connections to the purchasers pipework systems,dimensionsoftheterminalpoints,togetherwithweldpreparationsandweldingrecommendations.

18.4 Arecommendedtimescheduleforthenecessaryinterchangeoftechnicalinformation and drawings, to integrate the turbinegenerator and itsassociationequipmentintotheoverallplantdesign.

18.5 Requirement for the steamconditionsandquantity, forauxiliary steamforglandsealingduringstartup.

18.6 Informationonturbinefoundationsasdetailedinclause6.

19 Turbineplantwithregenerativefeedwaterheating19.1 Exchangeofinformation

Turbines for electrical power generation are usually arranged forregenerative feed water heating. The basis of the arrangement (seeclause 4) and the relevant details, indicated below, shall be agreedbetweenthepurchaserandthesupplierforoneormorespecificloads.

a) The number of bledsteam feedwater heating stages, andwhich ofthemaretobeprovided:

i) Fromthemainturbine

ii) From any auxiliary turbine which may be supplied for drivingother equipment, such as a boiler feed pump or auxiliarygeneratororsimilarplants.

b) Thenumberandarrangementof individualheatexchangervesselsforeachstageoffeedwaterheating;andwhethereachvessel issuppliedindependently from a turbine tappingpoint,or from aheaderwhichsuppliessteamtoallvesselsofthesamefeedwaterheatingstage.

c) Thepositionoffeedpumpsinthefeedwaterheatingcycle,thepressureof the feed water at the discharge of each pump, and the rise inenthalpyofthefeedwateracrosseachpump.

d) Thedesiredfeedwatertemperatureattheappropriateterminalpoint,andthepermissibledeviationfromthedesiredvalue.

Alsowhetherthefinalfeedwatertemperaturecanbeallowedtovarynaturallywithturbineloadand,ifnot,thepurchasersrequirementsinthisrespect.

e) Themethodofcascadingheaterdrains,andatwhichpointorpoints(ifany)thedrainsarepumpedforwardintothefeedwatersystem.

f) Theterminaltemperaturedifferenceforeachheater,i.e.thedifferencebetweenthesaturationtemperatureofthesteamintheheaterandthetemperatureofthefeedwaterleavingtheheater.

39

Note:Ifthereisdesuperheatingofthebledsteambeforeitisadmittedtothesaturation zone of the feed water heater, the complementary feed waterheatinginthedesuperheatermustbetakenintoaccount.

g) Theterminaltemperaturedifferenceforeachdraincooler(otherthanflash type),whether independentor integralwithbled steamheater,i.e.thedifferencebetweenthetemperatureoftheheatercondensateleaving the drain cooler and the temperature of the feed waterenteringthedraincooler.

h) The rise inenthalpyof the condensateoveranyheatexchanger(s) inthefeedwatersystemsnotprovidedbythesupplier.

i) The pressure drop from each extraction outlet on the turbine to theheaterorthedropinsaturationtemperaturefromextractionoutlettoheater.

j) Thetypeandthelocationinthesystemofthebledsteamevaporator(ifprovided), the quantity of makeup water required, the blowdownallowances for the evaporator, and the enthalpy of the raw waterenteringtheevaporator.

k) If thecondensate fromauxiliaryplant is tobedealtwithby the feedwater heating system; the quantity and the enthalpy of suchcondensate,and itspointof introduction into the feedwaterheatingsystem.

l) Particularsofanyoperatingconditionsgovernedotherwisethanbytheoutput of the turbine, for example, deaerator pressure when aminimumvalueisspecified,togetherwiththesourceandconditionsofanyalternativesteamsupplyavailabletosatisfysuchrequirements.

m) Where steam is supplied for feedwater heating purposes from thesourcesotherthanthemainturbine;thepressure,enthalpy,andflowrate from each source, and the destination of the condensed steam.Similarly,whereheat is suppliedby themediaother than steam, therelevantdetails.

19.2 Inclusion of feedwater heating systems performance into the turbineguarantee

When the turbine supplier supplies the feedwater heating system, itsperformance shallbe included in theguaranteeofperformance,unlessotherwiseagreed.

When the turbine supplier does not supply the feed water heatingsystem,theinformationlistedin19.1shallbestatedintheguaranteeofperformance.

The turbine supplier shall be given the opportunity of adjusting hisguarantees should the feedwater heating system finally agreed upondifferfromthesystemonwhichtheguaranteewasbased.

19.3 Provisionofnonreturnvalvesinbledsteampipesfromtheturbine

40

Thesuppliershalldeterminetheamountofoverspeedwhichtheturbinewill experience due to entrained steam, resulting from a lossofloadincidentoraturbinetrip.

Thenumber and typeofnonreturn (check) valves tobeplaced in thebled steam extraction pipes from the turbine shall, when the feedheatingplantisnotsuppliedbytheturbinesupplier,beagreedbetweenthepurchaserandtheturbinesupplier,andwillbebasedupontheoverspeedcalculations.

Itmay be possible to eliminate nonreturn (check) valves from someextraction lines,providedthatthequantityofsteamwhichcouldreturntotheturbinehasbeenevaluatedandthattheresultingeffectonoverspeedisacceptable.

ANNEXUREA

(Normative)

Electronicgovernors

A.1 General

A.1.1 Scope

Thisannexecoverstheelectronicsectionofelectrohydraulicgoverning(control)systems and overspeed protection equipment used on steam turbines. Therequirementsofclause5shallalsobeobservedwhereapplicable.

A.1.2 Classificationofgoverning(control)systems

1.2.1 Electronic governors are classified as follows to distinguishbetween the differing standards of performance, particularlyreliability,requiredforvariousapplications.

TypeA: Faulttolerantsystems, inwhichat leastonefaultcanbedetectedand repairedwithno lossoronly limited lossof systemavailability,andnolossofoverspeedlimitingcapability.Suchgoverning(control)system may, for example, have three parallel redundant principalprocessing paths in which a failure in one path, detected bycomparison, will give an alarm, and in which control will bemaintainedbyvotingarrangementsbetweenthepaths.

TypeB:Systemsinwhichfaultswillbedetectedandwillresultinunloadingor trippingof theunit for aproportionof single faults including allthose resulting in a loss of overspeed limiting capability. Suchgovernorsmay,forexample,havetwoprocessingpathsoronepathwithperformancemonitoring.

Type C: Systemswith the same characteristics as type B, except that thegoverning(control)systemoutputmaybeplacedinaholdstateforcertain fault conditions in preference to unloading or tripping the

41

turbine. In this state, the governing (control) systemwillmake nocontributionto limitingoverspeed,althoughthesystemoutputmaybemanuallycontrolled.

TypeD: Simplegoverning (control) systems, inwhich failureswillprobablycausecompletelossofavailability.

A.1.2.2 Governorsmayalsobeclassifiedaccordingtotheirinterfacewiththesteamadmissionvalvehydraulicrelays.

Typea): Systems with a separate electrohydraulic controller foreachsteamvalve,eachhavingfaultmonitoringprovisionandpossiblyinternal redundancy. This arrangement will normally be used withgovernorsofTypeAandTypeB.

Typeb): Systems with a common interface for all valves of theturbineorcontrolgroup.ThisarrangementwillnormallybeusedwithgovernorsofB,CorD.

A.1.3. Overspeedprotection

The requirements of 5.3 apply to mechanical and electrical overspeedprotection equipment, either of which may be used with electronicgovernors. Electronic overspeed protection may also be used withmechanical governors or in combination with mechanical overspeedequipment.

For centralpower station type turbines, theelectronicequipment shallbedesignedsothatnosinglefaultshalleithercauseatriporpreventatrip.Anysuitableformofredundancymaybeused.

For industrial turbine, it may be acceptable to combine the overspeedelectronicequipmentwiththegoverning(control)system.

A.1.4.Controlmethod

Electronicgovernorsmaybeanalogueordigitalcontrol,oracombinationofthe two. The use of sharedpurpose equipment (i.e. equipment which ispartly outside that provided by the turbine supplier) is not generallypermitted.

A.1.5.Powersupplies

ForgovernortypeA,at leasttwo independentelectricpowersuppliesshallbeprovidedbythepurchaser,soastomaintainunimpairedperformanceofthegovernorduringlossofasinglesupplyforanyperiod.

A.2.Facilitiestobeprovided

Thegovernorshallincludethefollowingfeatures;

a) Testpintsforonlinechecksandtests

b) Alarmstoindicatemodeofequipmentfailure

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c) Simplereplacementofmodules(onlinefortypeA)

d) Wherepartialarc control isused, the facilities to change to fullarcoperation,ifthisisnecessaryforanyparticularpurpose.

e) Suchotherfacilitiesasthepurchasermayspecify,forexample;

i) Remoteand/orlocalcontrol

ii) Interfaceswithothercontrolsystems

iii) Unloadingandtripprovision

iv) Variabledroop

v) Widerangeand/ornarrowrangecontrol

vi) Different sets of valves to be controlled (initial, reheat,extraction,etc)

vii) Speedand/orloadlimiting

viii) Directcontrolofvalveposition

A.3. Performancecharacteristics

The performance characteristics of an electrohydraulic governing system arelargelydeterminedbythemechanicalandhydrauliccomponentscontrollingthevalve positions and by the characteristics of the valves themselves. Unlessotherwiseagreed,theoverallcharacteristicsgiven in5.2.2shallbetakenasthespecifiedvaluesforsystemsincorporatingelectronicgovernors.

Thespeederdevice(loadreference)shallbecapableofadjustingtheoutput instepsnotexceeding0.5%ofratedoutput.

ValuesgivenforguidelinesofnonavailabilityandstabilityaregiveninTableA1.

TableA.1Nonlinearityandstability

TurbineMCR MW Upto20 20to50 Over150

Nonlinearity %ofMCR Notgreaterthan+3overrange0100%

MCR

Stability

Shortterm

Longterm

%ofMCR

2,5

10

1.5

10

1

10

A.4 Environment

TheequipmentshallbecapableofsatisfactoryandcontinuousoperationwithinwhicheveroftheclassesofenvironmentconditionsintableA2isspecified.

43

Forallthreeclasses,thefollowingstandardenvironmentalconditionsshallalsoapply;

vibration:10Hz65Hz,0.15mmamplitude

airpressure:68kPa106kPa

Theequipment shall function correctly in thepresenceof radio interfaceof anatureandleveltobespecified.

The equipment shall not generate radio interface exceeding a level to bespecified.

Class Ambienttemperaturerange

Ambientrelativehumidity

Typicalcondition

1 00Cto+400C 45%to75% Control rooms andequipmentrooms

2 250Cto+550C 45%to100% Outdoorsorplantsited

3 100Cto+700C 45%to100% Specialconditions

A.5 Tests

A.5.1Worktests

Theteststobewithheldbythepurchasershallbesubjecttoprioragreement.

A.5.2S