外文翻译--煤矿业带式输送机几种软起动方式的比较.doc外文翻译--煤矿业带式输送机几种软起动方式的比较.doc

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附录英文原文ACOMPARISONOFSOFTSTARTMECHANISMSFORMININGBELTCONVEYORSMICHAELLNAVE,PECONSOLINC1800WASHINGTONROADPITTSBURGH,PA15241BELTCONVEYORSAREANIMPORTANTMETHODFORTRANSPORTATIONOFBULKMATERIALSINTHEMININGINDUSTRYTHECONTROLOFTHEAPPLICATIONOFTHESTARTINGTORQUEFROMTHEBELTDRIVESYSTEMTOTHEBELTFABRICAFFECTSTHEPERFORMANCE,LIFECOST,ANDRELIABILITYOFTHECONVEYORTHISPAPEREXAMINESAPPLICATIONSOFEACHSTARTINGMETHODWITHINTHECOALMININGINDUSTRYINTRODUCTIONTHEFORCEREQUIREDTOMOVEABELTCONVEYORMUSTBETRANSMITTEDBYTHEDRIVEPULLEYVIAFRICTIONBETWEENTHEDRIVEPULLEYANDTHEBELTFABRICINORDERTOTRANSMITPOWERTHEREMUSTBEADIFFERENCEINTHEBELTTENSIONASITAPPROACHESANDLEAVESTHEDRIVEPULLEYTHESECONDITIONSARETRUEFORSTEADYSTATERUNNING,STARTING,ANDSTOPPINGTRADITIONALLY,BELTDESIGNSAREBASEDONSTATICCALCULATIONSOFRUNNINGFORCESSINCESTARTINGANDSTOPPINGARENOTEXAMINEDINDETAIL,SAFETYFACTORSAREAPPLIEDTOSTATICLOADINGSHARRISON,1987THISPAPERWILLPRIMARILYADDRESSTHESTARTINGORACCELERATIONDUTYOFTHECONVEYORTHEBELTDESIGNERMUSTCONTROLSTARTINGACCELERATIONTOPREVENTEXCESSIVETENSIONINTHEBELTFABRICANDFORCESINTHEBELTDRIVESYSTEMSUTTEES,1986HIGHACCELERATIONFORCESCANADVERSELYAFFECTTHEBELTFABRIC,BELTSPLICES,DRIVEPULLEYS,IDLERPULLEYS,SHAFTS,BEARINGS,SPEEDREDUCERS,ANDCOUPLINGSUNCONTROLLEDACCELERATIONFORCESCANCAUSEBELTCONVEYORSYSTEMPERFORMANCEPROBLEMSWITHVERTICALCURVES,EXCESSIVEBELTTAKEUPMOVEMENT,LOSSOFDRIVEPULLEYFRICTION,SPILLAGEOFMATERIALS,ANDFESTOONINGOFTHEBELTFABRICTHEBELTDESIGNERISCONFRONTEDWITHTWOPROBLEMS,THEBELTDRIVESYSTEMMUSTPRODUCEAMINIMUMTORQUEPOWERFULENOUGHTOSTARTTHECONVEYOR,ANDCONTROLLEDSUCHTHATTHEACCELERATIONFORCESAREWITHINSAFELIMITSSMOOTHSTARTINGOFTHECONVEYORCANBEACCOMPLISHEDBYTHEUSEOFDRIVETORQUECONTROLEQUIPMENT,EITHERMECHANICALORELECTRICAL,ORACOMBINATIONOFTHETWOCEM,1979SOFTSTARTMECHANISMEVALUATIONCRITERIONWHATISTHEBESTBELTCONVEYORDRIVESYSTEMTHEANSWERDEPENDSONMANYVARIABLESTHEBESTSYSTEMISONETHATPROVIDESACCEPTABLECONTROLFORSTARTING,RUNNING,ANDSTOPPINGATAREASONABLECOSTANDWITHHIGHRELIABILITYLEWDLYANDSUGARCANE,1978BELTDRIVESYSTEMFORTHEPURPOSESOFTHISPAPERWEWILLASSUMETHATBELTCONVEYORSAREALMOSTALWAYSDRIVENBYELECTRICALPRIMEMOVERSGOODYEARTIREANDRUBBER,1982THEBELTDRIVESYSTEMSHALLCONSISTOFMULTIPLECOMPONENTSINCLUDINGTHEELECTRICALPRIMEMOVER,THEELECTRICALMOTORSTARTERWITHCONTROLSYSTEM,THEMOTORCOUPLING,THESPEEDREDUCER,THELOWSPEEDCOUPLING,THEBELTDRIVEPULLEY,ANDTHEPULLEYBRAKEORHOLDBACKCUR,1986ITISIMPORTANTTHATTHEBELTDESIGNEREXAMINETHEAPPLICABILITYOFEACHSYSTEMCOMPONENTTOTHEPARTICULARAPPLICATIONFORTHEPURPOSEOFTHISPAPER,WEWILLASSUMETHATALLDRIVESYSTEMCOMPONENTSARELOCATEDINTHEFRESHAIR,NONPERMISSIBLE,AREASOFTHEMINE,ORINNONHAZARDOUS,NATIONALELECTRICALCODE,ARTICLE500EXPLOSIONPROOF,AREASOFTHESURFACEOFTHEMINEBELTDRIVECOMPONENTATTRIBUTESSIZECERTAINDRIVECOMPONENTSAREAVAILABLEANDPRACTICALINDIFFERENTSIZERANGESFORTHISDISCUSSION,WEWILLASSUMETHATBELTDRIVESYSTEMSRANGEFROMFRACTIONALHORSEPOWERTOMULTIPLESOFTHOUSANDSOFHORSEPOWERSMALLDRIVESYSTEMSAREOFTENBELOW50HORSEPOWERMEDIUMSYSTEMSRANGEFROM50TO1000HORSEPOWERLARGESYSTEMSCANBECONSIDEREDABOVE1000HORSEPOWERDIVISIONOFSIZESINTOTHESEGROUPSISENTIRELYARBITRARYCAREMUSTBETAKENTORESISTTHETEMPTATIONTOOVERMOTORORUNDERMOTORABELTFLIGHTTOENHANCESTANDARDIZATIONANOVERMOTOREDDRIVERESULTSINPOOREFFICIENCYANDTHEPOTENTIALFORHIGHTORQUES,WHILEANUNDERMOTOREDDRIVECOULDRESULTINDESTRUCTIVEOVERSPENDINGONREGENERATION,OROVERHEATINGWITHSHORTENEDMOTORLIFELORDS,ETAL,1978TORQUECONTROLBELTDESIGNERSTRYTOLIMITTHESTARTINGTORQUETONOMORETHAN150OFTHERUNNINGTORQUECEMA,1979;GOODYEAR,1982THELIMITONTHEAPPLIEDSTARTINGTORQUEISOFTENTHELIMITOFRATINGOFTHEBELTCARCASS,BELTSPLICE,PULLEYLAGGING,ORSHAFTDEFLECTIONSONLARGERBELTSANDBELTSWITHOPTIMIZEDSIZEDCOMPONENTS,TORQUELIMITSOF110THROUGH125ARECOMMONELBERTON,1986INADDITIONTOATORQUELIMIT,THEBELTSTARTERMAYBEREQUIREDTOLIMITTORQUEINCREMENTSTHATWOULDSTRETCHBELTINGANDCAUSETRAVELINGWAVESANIDEALSTARTINGCONTROLSYSTEMWOULDAPPLYAPRETENSIONTORQUETOTHEBELTATRESTUPTOTHEPOINTOFBREAKAWAY,ORMOVEMENTOFTHEENTIREBELT,THENATORQUEEQUALTOTHEMOVEMENTREQUIREMENTSOFTHEBELTWITHLOADPLUSACONSTANTTORQUETOACCELERATETHEINERTIAOFTHESYSTEMCOMPONENTSFROMRESTTOFINALRUNNINGSPEEDTHISWOULDMINIMIZESYSTEMTRANSIENTFORCESANDBELTSTRETCHSHULTZ,1992DIFFERENTDRIVESYSTEMSEXHIBITVARYINGABILITYTOCONTROLTHEAPPLICATIONOFTORQUESTOTHEBELTATRESTANDATDIFFERENTSPEEDSALSO,THECONVEYORITSELFEXHIBITSTWOEXTREMESOFLOADINGANEMPTYBELTNORMALLYPRESENTSTHESMALLESTREQUIREDTORQUEFORBREAKAWAYANDACCELERATION,WHILEAFULLYLOADEDBELTPRESENTSTHEHIGHESTREQUIREDTORQUEAMININGDRIVESYSTEMMUSTBECAPABLEOFSCALINGTHEAPPLIEDTORQUEFROMA2/1RATIOFORAHORIZONTALSIMPLEBELTARRANGEMENT,TOA10/1RANGESFORANINCLINEDORCOMPLEXBELTPROFILETHERMALRATINGDURINGSTARTINGANDRUNNING,EACHDRIVESYSTEMMAYDISSIPATEWASTEHEATTHEWASTEHEATMAYBELIBERATEDINTHEELECTRICALMOTOR,THEELECTRICALCONTROLS,,THECOUPLINGS,THESPEEDREDUCER,ORTHEBELTBRAKINGSYSTEMTHETHERMALLOADOFEACHSTARTISDEPENDENTONTHEAMOUNTOFBELTLOADANDTHEDURATIONOFTHESTARTTHEDESIGNERMUSTFULFILLTHEAPPLICATIONREQUIREMENTSFORREPEATEDSTARTSAFTERRUNNINGTHECONVEYORATFULLLOADTYPICALMININGBELTSTARTINGDUTIESVARYFROM3TO10STARTSPERHOUREQUALLYSPACED,OR2TO4STARTSINSUCCESSIONREPEATEDSTARTINGMAYREQUIRETHEDREADINGOROVERSIZINGOFSYSTEMCOMPONENTSTHEREISADIRECTRELATIONSHIPBETWEENTHERMALRATINGFORREPEATEDSTARTSANDCOSTSVARIABLESPEEDSOMEBELTDRIVESYSTEMSARESUITABLEFORCONTROLLINGTHESTARTINGTORQUEANDSPEED,BUTONLYRUNATCONSTANTSPEEDSOMEBELTAPPLICATIONSWOULDREQUIREADRIVESYSTEMCAPABLEOFRUNNINGFOREXTENDEDPERIODSATLESSTHANFULLSPEEDTHISISUSEFULWHENTHEDRIVELOADMUSTBESHAREDWITHOTHERDRIVES,THEBELTISUSEDASAPROCESSFEEDERFORRATECONTROLOFTHECONVEYEDMATERIAL,THEBELTSPEEDISOPTIMIZEDFORTHEHAULAGERATE,THEBELTISUSEDATSLOWERSPEEDSTOTRANSPORTMENORMATERIALS,ORTHEBELTISRUNASLOWINSPECTIONORINCHINGSPEEDFORMAINTENANCEPURPOSESHAGER,1991THEVARIABLESPEEDBELTDRIVEWILLREQUIREACONTROLSYSTEMBASEDONSOMEALGORITHMTOREGULATEOPERATINGSPEEDREGENERATIONOROVERHAULINGLOADSOMEBELTPROFILESPRESENTTHEPOTENTIALFOROVERHAULINGLOADSWHERETHEBELTSYSTEMSUPPLIESENERGYTOTHEDRIVESYSTEMNOTALLDRIVESYSTEMSHAVETHEABILITYTOACCEPTREGENERATEDENERGYFROMTHELOADSOMEDRIVESCANACCEPTENERGYFROMTHELOADANDRETURNITTOTHEPOWERLINEFORUSEBYOTHERLOADSOTHERDRIVESACCEPTENERGYFROMTHELOADANDDISSIPATEITINTODESIGNATEDDYNAMICORMECHANICALBRAKINGELEMENTSSOMEBELTPROFILESSWITCHFROMMOTORINGTOREGENERATIONDURINGOPERATIONCANTHEDRIVESYSTEMACCEPTREGENERATEDENERGYOFACERTAINMAGNITUDEFORTHEAPPLICATIONDOESTHEDRIVESYSTEMHAVETOCONTROLORMODULATETHEAMOUNTOFRETARDINGFORCEDURINGOVERHAULINGDOESTHEOVERHAULINGOCCURWHENRUNNINGANDSTARTINGMAINTENANCEANDSUPPORTINGSYSTEMSEACHDRIVESYSTEMWILLREQUIREPERIODICPREVENTATIVEMAINTENANCEREPLACEABLEITEMSWOULDINCLUDEMOTORBRUSHES,BEARINGS,BRAKEPADS,DISSIPATIONRESISTORS,OILS,ANDCOOLINGWATERIFTHEDRIVESYSTEMISCONSERVATIVELYENGINEEREDANDOPERATED,THELOWERSTRESSONCONSUMABLESWILLRESULTINLOWERMAINTENANCECOSTSSOMEDRIVESREQUIRESUPPORTINGSYSTEMSSUCHASCIRCULATINGOILFORLUBRICATION,COOLINGAIRORWATER,ENVIRONMENTALDUSTFILTERING,ORCOMPUTERINSTRUMENTATIONTHEMAINTENANCEOFTHESUPPORTINGSYSTEMSCANAFFECTTHERELIABILITYOFTHEDRIVESYSTEMCOSTTHEDRIVEDESIGNERWILLEXAMINETHECOSTOFEACHDRIVESYSTEMTHETOTALCOSTISTHESUMOFTHEFIRSTCAPITALCOSTTOACQUIRETHEDRIVE,THECOSTTOINSTALLANDCOMMISSIONTHEDRIVE,THECOSTTOOPERATETHEDRIVE,ANDTHECOSTTOMAINTAINTHEDRIVETHECOSTFORPOWERTOOPERATETHEDRIVEMAYVARYWIDELYWITHDIFFERENTLOCATIONSTHEDESIGNERSTRIVESTOMEETALLSYSTEMPERFORMANCEREQUIREMENTSATLOWESTTOTALCOSTOFTENMORETHANONEDRIVESYSTEMMAYSATISFYALLSYSTEMPERFORMANCECRITERIONSATCOMPETITIVECOSTSCOMPLEXITYTHEPREFERREDDRIVEARRANGEMENTISTHESIMPLEST,SUCHASASINGLEMOTORDRIVINGTHROUGHASINGLEHEADPULLEYHOWEVER,MECHANICAL,ECONOMIC,ANDFUNCTIONALREQUIREMENTSOFTENNECESSITATETHEUSEOFCOMPLEXDRIVESTHEBELTDESIGNERMUSTBALANCETHENEEDFORSOPHISTICATIONAGAINSTTHEPROBLEMSTHATACCOMPANYCOMPLEXSYSTEMSCOMPLEXSYSTEMSREQUIREADDITIONALDESIGNENGINEERINGFORSUCCESSFULDEPLOYMENTANOFTENOVERLOOKEDCOSTINACOMPLEXSYSTEMISTHECOSTOFTRAININGONSITEPERSONNEL,ORTHECOSTOFDOWNTIMEASARESULTOFINSUFFICIENTTRAININGSOFTSTARTDRIVECONTROLLOGICEACHDRIVESYSTEMWILLREQUIREACONTROLSYSTEMTOREGULATETHESTARTINGMECHANISMTHEMOSTCOMMONTYPEOFCONTROLUSEDONSMALLERTOMEDIUMSIZEDDRIVESWITHSIMPLEPROFILESISTERMEDOPENLOOPACCELERATIONCONTROLINOPENLOOP,THECONTROLSYSTEMISPREVIOUSLYCONFIGUREDTOSEQUENCETHESTARTINGMECHANISMINAPRESCRIBEDMANNER,USUALLYBASEDONTIMEINOPENLOOPCONTROL,DRIVEOPERATINGPARAMETERSSUCHASCURRENT,TORQUE,ORSPEEDDONOTINFLUENCESEQUENCEOPERATIONTHISMETHODPRESUMESTHATTHECONTROLDESIGNERHASADEQUATELYMODELEDDRIVESYSTEMPERFORMANCEONTHECONVEYORFORLARGERORMORECOMPLEXBELTS,CLOSEDLOOPORFEEDBACKCONTROLMAYHEUTILIZEDINCLOSEDLOOPCONTROL,DURINGSTARTING,THECONTROLSYSTEMMONITORSVIASENSORSDRIVEOPERATINGPARAMETERSSUCHASCURRENTLEVELOFTHEMOTOR,SPEEDOFTHEBELT,ORFORCEONTHEBELT,ANDMODIFIESTHESTARTINGSEQUENCETOCONTROL,LIMIT,OROPTIMIZEONEORWOREPARAMETERSCLOSEDLOOPCONTROLSYSTEMSMODIFYTHESTARTINGAPPLIEDFORCEBETWEENANEMPTYANDFULLYLOADEDCONVEYORTHECONSTANTSINTHEMATHEMATICALMODELRELATEDTOTHEMEASUREDVARIABLEVERSUSTHESYSTEMDRIVERESPONSEARETERMEDTHETUNINGCONSTANTSTHESECONSTANTSMUSTBEPROPERLYADJUSTEDFORSUCCESSFULAPPLICATIONTOEACHCONVEYORTHEMOSTCOMMONSCHEMESFORCLOSEDLOOPCONTROLOFCONVEYORSTARTSARETACHOMETERFEEDBACKFORSPEEDCONTROLANDLOADCELLFORCEORDRIVEFORCEFEEDBACKFORTORQUECONTROLONSOMECOMPLEXSYSTEMS,ITISDESIRABLETOHAVETHECLOSEDLOOPCONTROLSYSTEMADJUSTITSELFFORVARIOUSENCOUNTEREDCONVEYORCONDITIONSTHISISTERMEDADAPTIVECONTROLTHESEEXTREMESCANINVOLVEVASTVARIATIONSINLOADINGS,TEMPERATUREOFTHEBELTING,LOCATIONOFTHELOADINGONTHEPROFILE,ORMULTIPLEDRIVEOPTIONSONTHECONVEYORTHEREARETHREECOMMONADAPTIVEMETHODSTHEFIRSTINVOLVESDECISIONSMADEBEFORETHESTART,ORRESTARTCONDITIONINGIFTHECONTROLSYSTEMCOULDKNOWTHATTHEBELTISEMPTY,ITWOULDREDUCEINITIALFORCEANDLENGTHENTHEAPPLICATIONOFACCELERATIONFORCETOFULLSPEEDIFTHEBELTISLOADED,THECONTROLSYSTEMWOULDAPPLYPRETENSIONFORCESUNDERSTALLFORLESSTIMEANDSUPPLYSUFFICIENTTORQUETOADEQUATELY
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