外文翻译-煤矿业带式输送机几种软起动方式的比较

第1页英文原文AComparisonofSoftStartMechanismsforMiningBeltConveyorsINTRODUCTION：Theforcerequiredtomoveabeltconveyormustbetransmittedbythedrivepulleyviafrictionbetweenthedrivepulleyandthebeltfabric.Inordertotransmitpowertheremustbeadifferenceinthebelttensionasitapproachesandleavesthedrivepulley.Theseconditionsaretrueforsteadystaterunning,starting,andstopping.Traditionally,beltdesignsarebasedonstaticcalculationsofrunningforces.Sincestartingandstoppingarenotexaminedindetail,safetyfactorsareappliedtostaticloadings(Harrison,1987).Thispaperwillprimarilyaddressthestartingoraccelerationdutyoftheconveyor.Thebeltdesignermustcontrolstartingaccelerationtopreventexcessivetensioninthebeltfabricandforcesinthebeltdrivesystem(Suttees,1986).Highaccelerationforcescanadverselyaffectthebeltfabric,beltsplices,drivepulleys,idlerpulleys,shafts,bearings,speedreducers,andcouplings.Uncontrolledaccelerationforcescancausebeltconveyorsystemperformanceproblemswithverticalcurves,excessivebelttake-upmovement,lossofdrivepulleyfriction,spillageofmaterials,andfestooningofthebeltfabric.Thebeltdesignerisconfrontedwithtwoproblems,Thebeltdrivesystemmustproduceaminimumtorquepowerfulenoughtostarttheconveyor,andcontrolledsuchthattheaccelerationforcesarewithinsafelimits.Smoothstartingoftheconveyorcanbeaccomplishedbytheuseofdrivetorquecontrolequipment,eithermechanicalorelectrical,oracombinationofthetwo(CEM,1979).SOFTSTARTMECHANISMEVALUATIONCRITERIONWhatisthebestbeltconveyordrivesystem?Theanswerdependsonmanyvariables.Thebestsystemisonethatprovidesacceptablecontrolforstarting,running,andstoppingatareasonablecostandwithhighreliability(LewdlyandSugarcane,1978).BeltDriveSystemForthepurposesofthispaperwewillassumethatbeltconveyorsarealmostalwaysdrivenbyelectricalprimemovers(GoodyearTireandRubber,1982).Thebeltdrivesystemshallconsistofmultiplecomponentsincludingtheelectricalprimemover,theelectricalmotorstarterwithcontrolsystem,themotorcoupling,thespeedreducer,thelowspeedcoupling,thebeltdrivepulley,andthepulleybrakeorholdback(Cur,1986).Itisimportantthatthebeltdesignerexaminetheapplicabilityofeachsystemcomponenttotheparticularapplication.Forthepurposeofthispaper,wewillassumealldrivesystemcomponentsarelocatedinthefreshair,non-permissible,areasofthemine,orinnon-hazardous,NationalElectricalCode,Article500explosion-proof,areasofthesurfaceofthemine.BeltDriveComponentAttributesSize.Certaindrivecomponentsareavailableandpracticalindifferentsizeranges.Forthisdiscussion,wewillassumethatbeltdrivesystemsrangefromfractionalhorsepowertomultiplesofthousandsofhorsepower.Smalldrivesystemsareoftenbelow50horsepower.Medium第2页systemsrangefrom50to1000horsepower.Largesystemscanbeconsideredabove1000horsepower.Divisionofsizesintothesegroupsisentirelyarbitrary.Caremustbetakentoresistthetemptationtoovermotororundermotorabeltflighttoenhancestandardization.Anovermotoreddriveresultsinpoorefficiencyandthepotentialforhightorques,whileanundermotoreddrivecouldresultindestructiveoverspendingonregeneration,oroverheatingwithshortenedmotorlife(Lords,etal.,1978).TorqueControl.Beltdesignerstrytolimitthestartingtorquetonomorethan150%oftherunningtorque(CEMA,1979;Goodyear,1982).Thelimitontheappliedstartingtorqueisoftenthelimitofratingofthebeltcarcass,beltsplice,pulleylagging,orshaftdeflections.Onlargerbeltsandbeltswithoptimizedsizedcomponents,torquelimitsof110%through125%arecommon(Elberton,1986).Inadditiontoatorquelimit,thebeltstartermayberequiredtolimittorqueincrementsthatwouldstretchbeltingandcausetravelingwaves.Anidealstartingcontrolsystemwouldapplyapretensiontorquetothebeltatrestuptothepointofbreakaway,ormovementoftheentirebelt,thenatorqueequaltothemovementrequirementsofthebeltwithloadplusaconstanttorquetoacceleratetheinertiaofthesystemcomponentsfromresttofinalrunningspeed.Thiswouldminimizesystemtransientforcesandbeltstretch(Shultz,1992).Differentdrivesystemsexhibitvaryingabilitytocontroltheapplicationoftorquestothebeltatrestandatdifferentspeeds.Also,theconveyoritselfexhibitstwoextremesofloading.Anemptybeltnormallypresentsthesmallestrequiredtorqueforbreakawayandacceleration,whileafullyloadedbeltpresentsthehighestrequiredtorque.Aminingdrivesystemmustbecapableofscalingtheappliedtorquefroma2/1ratioforahorizontalsimplebeltarrangement,toa10/1rangesforaninclinedorcomplexbeltprofile.ThermalRating.Duringstartingandrunning,eachdrivesystemmaydissipatewasteheat.Thewasteheatmaybeliberatedintheelectricalmotor,theelectricalcontrols,thecouplings,thespeedreducer,orthebeltbrakingsystem.ThethermalloadofeachstartIsdependentontheamountofbeltloadandthedurationofthestart.Thedesignermustfulfilltheapplicationrequirementsforrepeatedstartsafterrunningtheconveyoratfullload.Typicalminingbeltstartingdutiesvaryfrom3to10startsperhourequallyspaced,or2to4startsinsuccession.Repeatedstartingmayrequirethedreadingoroversizingofsystemcomponents.Thereisadirectrelationshipbetweenthermalratingforrepeatedstartsandcosts.VariableSpeed.Somebeltdrivesystemsaresuitableforcontrollingthestartingtorqueandspeed,butonlyrunatconstantspeed.Somebeltapplicationswouldrequireadrivesystemcapableofrunningforextendedperiodsatlessthanfullspeed.Thisisusefulwhenthedriveloadmustbesharedwithotherdrives,thebeltisusedasaprocessfeederforratecontroloftheconveyedmaterial,thebeltspeedisoptimizedforthehaulagerate,thebeltisusedatslowerspeedstotransportmenormaterials,orthebeltisrunaslowinspectionorinchingspeedformaintenancepurposes(Hager,1991).Thevariablespeedbeltdrivewill第3页requireacontrolsystembasedonsomealgorithmtoregulateoperatingspeed.RegenerationorOverhaulingLoad.Somebeltprofilespresentthepotentialforoverhaulingloadswherethebeltsystemsuppliesenergytothedrivesystem.Notalldrivesystemshavetheabilitytoacceptregeneratedenergyfromtheload.Somedrivescanacceptenergyfromtheloadandreturnittothepowerlineforusebyotherloads.Otherdrivesacceptenergyfromtheloadanddissipateitintodesignateddynamicormechanicalbrakingelements.Somebeltprofilesswitchfrommotoringtoregenerationduringoperation.Canthedrivesystemacceptregeneratedenergyofacertainmagnitudefortheapplication?Doesthedrivesystemhavetocontrolormodulatetheamountofretardingforceduringoverhauling?Doestheoverhaulingoccurwhenrunningandstarting?MaintenanceandSupportingSystems.Eachdrivesystemwillrequireperiodicpreventativemaintenance.Replaceableitemswouldincludemotorbrushes,bearings,brakepads,dissipationresistors,oils,andcoolingwater.Ifthedrivesystemisconservativelyengineeredandoperated,thelowerstressonconsumableswillresultinlowermaintenancecosts.Somedrivesrequiresupportingsystemssuchascirculatingoilforlubrication,coolingairorwater,environmentaldustfiltering,orcomputerinstrumentation.Themaintenanceofthesupportingsystemscanaffectthereliabilityofthedrivesystem.Cost.Thedrivedesignerwillexaminethecostofeachdrivesystem.Thetotalcostisthesumofthefirstcapitalcosttoacquirethedrive,thecosttoinstallandcommissionthedrive,thecosttooperatethedrive,andthecosttomaintainthedrive.Thecostforpowertooperatethedrivemayvarywidelywithdifferentlocations.Thedesignerstrivestomeetallsystemperformancerequirementsatlowesttotalcost.Oftenmorethanonedrivesystemmaysatisfyallsystemperformancecriterionsatcompetitivecosts.Complexity.Thepreferreddrivearrangementisthesimplest,suchasasinglemotordrivingthroughasingleheadpulley.However,mechanical,economic,andfunctionalrequirementsoftennecessitatetheuseofcomplexdrives.Thebeltdesignermustbalancetheneedforsophisticationagainsttheproblemsthataccompanycomplexsystems.Complexsystemsrequireadditionaldesignengineeringforsuccessfuldeployment.Anoften-overlookedcostinacomplexsystemisthecostoftrainingonsitepersonnel,orthecostofdowntimeasaresultofinsufficienttraining.SOFTSTARTDRIVECONTROLLOGICEachdrivesystemwillrequireacontrolsystemtoregulatethestartingmechanism.ThemostcommontypeofcontrolusedonsmallertomediumsizeddriveswithsimpleprofilesistermedOpenLoopAccelerationControl.Inopenloop,thecontrolsystemispreviouslyconfiguredtosequencethestartingmechanisminaprescribedmanner,usuallybasedontime.Inopenloopcontrol,drive-operatingparameterssuchascurrent,torque,orspeeddonotinfluencesequenceoperation.Thismethodpresumesthatthecontroldesignerhasadequatelymodeleddrivesystemperformanceontheconveyor.Forlargerormorecomplexbelts,ClosedLoopor第4页Feedbackcontrolmayheutilized.Inclosedloopcontrol,duringstarting,thecontrolsystemmonitorsviasensorsdriveoperatingparameterssuchascurrentlevelofthemotor,speedofthebelt,orforceonthebelt,andmodifiesthestartingsequencetocontrol,limit,oroptimizeoneorworeparameters.Closedloopcontrolsystemsmodifythestartingappliedforcebetweenanemptyandfullyloadedconveyor.Theconstantsinthemathematicalmodelrelatedtothemeasuredvariableversusthesystemdriveresponsearetermedthetuningconstants.Theseconstantsmustbeproperlyadjustedforsuccessfulapplicationtoeachconveyor.Themostcommonschemesforclosedloopcontrolofconveyorstartsaretachometerfeedbackforspeedcontrolandloadcellforceordriveforcefeedbackfortorquecontrol.Onsomecomplexsystems,Itisdesirabletohavetheclosedloopcontrolsystemadjustitselfforvariousencounteredconveyorconditions.ThisistermedAdaptiveControl.Theseextremescaninvolvevastvariationsinloadings,temperatureofthebelting,locationoftheloadingontheprofile,ormultipledriveoptionsontheconveyor.Therearethreecommonadaptivemethods.Thefirstinvolvesdecisionsmadebeforethestart,orRestartConditioning.Ifthecontrolsystemcouldknowthatthebeltisempty,itwouldreduceinitialforceandlengthentheapplicationofaccelerationforcetofullspeed.Ifthebeltisloaded,thecontrolsystemwouldapplypretensionforcesunderstallforlesstimeandsupplysufficienttorquetoadequatelyacceleratethebeltinatimelymanner.Sincethebeltonlybecameloadedduringpreviousrunningbyloadingthedrive,theaveragedrivecurrentcanbesampledwhenrunningandretainedinafirst-in-first-outbuffermemorythatreflectsthebeltconveyancetime.ThenatshutdotheFIFOaveragemaybeuse4topreconditionsomeopenloopandclosedloopsetpointsforthenextstart.ThesecondmethodinvolvesdecisionsthatarebasedondriveobservationsthatoccurduringinitialstartingorMotionProving.ThisusuallyinvolvesacomparisonIntimeofthedrivecurrentorforceversusthebeltspeed.ifthedrivecurrentorforcerequiredearlyinthesequenceislowandmotionisinitiated,thebeltmustbeunloaded.Ifthedrivecurrentorforcerequiredishighandmotionisslowinstarting,theconveyormustbeloaded.Thisdecisioncanbedividedinzonesandusedtomodifythemiddleandfinishofthestartsequencecontrol.Thethirdmethodinvolvesacomparisonofthebeltspeedversustimeforthisstartagainsthistoricallimitsofbeltacceleration,orAccelerationEnvelopeMonitoring.Atstart,thebeltspeedismeasuredversustime.Thisiscomparedwithtwolimitingbeltspeedcurvesthatareretainedincontrolsystemmemory.Thefirstcurveprofilestheemptybeltwhenaccelerated,andthesecondonethefullyloadedbelt.Thus,ifthecurrentspeedversustimeislowerthantheloadedprofile,itmayindicatethatthebeltisoverloaded,impeded,ordrivemalfunction.Ifthecurrentspeedversustimeishigherthantheemptyprofile,itmayindicateabrokenbelt,coupling,ordrivemalfunction.Ineithercase,thecurrentstartisabortedandanalarmissued.CONCLUSIONThebestbeltstartingsystemisonethatprovidesacceptableperformanceunderallbeltload第5页Conditionsatareasonablecostwithhighreliability.Noonestartingsystemmeetsallneeds.Thebeltdesignermustdefinethestartingsystemattributesthatarerequiredforeachbelt.Ingeneral,theACinductionmotorwithfullvoltagestartingisconfinedtosmallbeltswithsimpleprofiles.TheACinductionmotorwithreducedvoltageSCRstartingisthebasecaseminingstarterforundergroundbeltsfromsmalltomediumsizes.Withrecentimprovements,theACmotorwithfixedfillfluidcouplingsisthebasecaseformediumtolargeconveyorswithsimpleprofiles.TheWoundRotorInductionMotordriveisthetraditionalchoiceformediumtolargebeltswithrepeatedstartingdutyorcomplexprofilesthatrequireprecisetorquecontrol.TheDCmotordrive,VariableFillHydrokineticdrive,andtheVariableMechanicalTransmissiondrivecompeteforapplicationonbeltswithextremeprofilesorvariablespeedatrunningrequirements.Thechoiceisdependentonlocationenvironment,competitiveprice,operatingenergylosses,speedresponse,anduserfamiliarity.ACVariableFrequencydriveandBrushlessDCapplicationsarelimitedtosmalltomediumsizedbeltsthatrequireprecisespeedcontrolduetohigherpresentcostsandcomplexity.However,withcontinuingcompetitiveandtechnicalimprovements,theuseofsynthesizedwaveformelectronicdriveswillexpand.第6页中文译文煤矿业带式输送机几种软起动方式的比较简介：运行带式运送机的动力必须由驱动滑轮产生，通过滑轮和传送带之间的摩擦力来传递。为了传递能量，传送带上面的张力在接近滑轮部分和离开滑轮部分必定存在着差别。这种差别在稳定运行、启动和停止时刻都是真实存在的。传统传送带结构的设计，都是根据稳定运行情况下传送带的受力情况。因为设计过程中没有详尽研究传送带启动和停止阶段的受力情况，所有的安全措施都集中在稳定运行阶段（Harrison1987）。本文主要集中讲述传送机启动和加速阶段的特性。传送带设计者在设计时必须考虑控制启动阶段的加速状况，以免使传送带和传送机驱动系统产生过大的张力和动力（Suttees，1986）。大加速度产生的动力会给传送带的纹理、传送带结合处、驱动滑轮、轴承、减速器以及耦合器带来负面影响。毫无控制的加速度产生的动力能够引起带式传送机系统产生诸多不良问题，比如上下曲线运动、过度传送带提升运动、滑轮和传送带打滑、运输原料的溢出和传送带结构。传送带的设计需要面对两个问题：第一，传送带驱动系统必须能够产生启动带式传送机的最小转动力矩；第二，控制加速度产生动力在安全界限内。可以通过驱动力矩控制设备来完成，控制设备可以是电子手段也可以是机械手段，也可以是两者的组合（CEM，1979）。本文主要阐述输送机的开始和加速的过程。传送带设计师必须控制开始加速度防止过度张紧在传送带织品和力量在皮带传动系统.强加速度力量可能有害地影响传送带织品，传送带接合，驱动皮带轮，更加无所事事的滑轮,轴,轴承,速度还原剂,并且联结。未管制的加速度力量可能造成皮带输送机有垂直的曲线的系统性能问题,传送带紧线器运动,驱动皮带轮摩擦损失,材料溢出,并且做成花彩传送带织品。传送带设计员与二个问题被面对,皮带传动系统必须导致极小的扭矩足够强有力开始传动机,和控制了这样加速度强制是在安全限额内。光滑开始传动机可能由对驱动器扭矩控制设备的用途,或机械或电子,或组合的二完成(CEM1979)。软起动结构评估标准什么是最佳的皮带输送机驱动系统?答案取决于许多变量。最佳的系统是一个为开始,运行,和终止提供可接受的控制在合理的费用和以及高可靠性。皮带传动系统为本文我们考虑的设计方案,皮带输送机被电子头等搬家工人几乎总驱动。传送带驱动系统将包括多个要素包括电子原动力、电子马达起始者以控制系统,马达联结、速度还原剂、低速联结、皮带传动滑轮、和滑轮闸(Cur1986)。它重要,传送带设计员审查各个系统要素的适用性对特殊申请。为本文的目的,我们假设,所有驱动系统要素设置矿的新鲜空气,非允许,面积,全国电子编码,条款500防爆,矿的表面的面积。皮带传动要素归因于范围。某些驱动器要素是可利用和实用的用不同的范围。为这论述,我们假设那皮带传动系统范围从分数马力对千位的多个马力。小驱动系统经常是在50马力以下。中型系统范围从50到1000马力。大型系统可能被考虑在1000马力之上。范围分部入这些组是整个地任意的。必须被保重抵抗诱惑对超出马达或在马达之下传送带飞行提高标准化。驱动器第7页结果在粗劣的效率和在高扭矩的潜在,当驱动器能导致破坏性超速在再生,或过度加热以变短的马达寿命。扭矩控制。传送带设计员设法限制开始的扭矩到没有比150%运行中。限额在应用的开始的扭矩经常是传送带胴体肉、传送带接合、滑轮绝热材料,轴偏折评级。在更大的传送带和传送带以优化大小的要素,扭矩限额110%至125%是公用。除扭矩限额之外,传送带起始者必需限制会舒展围绕和会导致旅行的波浪的扭矩增量。一个理想的开始的控制系统会适用于资格整个传送带的扭矩传送带休息由问题的脱离决定,或运动,然后扭矩相等与传送带的运动需求以负荷加上恒定的扭矩从休息加速系统要素的惯性对最终奔跑速度。这使系统临时强制和传送带舒展。不同的驱动系统陈列变化的能力控制扭矩的申请对传送带休息和以不同的速度。并且,传动机陈列装载二个极端。一条空传送带正常存在最小的必需的扭矩为脱离和加速度,当一条充分地被装载的传送带存在最高的必需的扭矩。开采驱动系统必须是能称应用的扭矩从一个2/1比率为一个水平的简单传送带安排,对一个10/1范围为一个倾斜、复杂传送带配置文件。热量评级在开始和运行期间,各个驱动系统也许消散废热。废热也许被解放在电子马达、电子控制、,联结、速度还原剂,或传送带制动系统。各个起始时间热量负荷依靠相当数量传送带负荷和起始时间的期限。设计员必须履行被重复的起始时间的申请需求在运行传动机以后在全负荷。典型的开采传送带开始的责任变化从3到10个起始时间每时数等隔,或2到4个起始时间在连续。被重复的开始也许要求减税或系统要素。有一个直接关系在热量评级为被重复的起始时间和费用之间。可变速度。一些皮带传动系统是适当的为控制开始的扭矩和速度,但只运行以恒定的速度。一些传送带申请会要求一个驱动系统能运行延长的期间以较不比最高速度。这是有用的当驱动器负荷必须与其它驱动器被共享,传送带被使用当处理饲养者为被表达的物料的费率控制,传送带速度被优选为货车使用费费率,传送带被使用以慢速运输人工或材料,或传送带运行缓慢的检验或移动速度为维护目的。可变速度皮带传动将要求一个控制系统根据某一算法调控操作速度。再生或翻修负荷。一些传送带配置文件存在翻修传送带系统用品能量对驱动系统的负荷的潜在。没有所有驱动系统有能力接受被重新生成的能量从负荷。一些驱动器可能接受能量从负荷和退回它到输电线供其它负荷使用。其它驱动器接受能量从负荷和消散它入选定的动态或机械刹车的要素。一些传送带描出切换从开汽车对再生在运算期间。驱动系统可能接受有些巨大的被重新生成的能量为申请吗?驱动系统控制或必须调整相当数量减速的强制在翻修期间吗?翻修发生当运行和开始?维护和支持系统。各个驱动系统将要求定期预防维护。可替换的项目会包括马达画笔、轴承、闸填充、散逸电阻器、油,和凉水。如果驱动系统被设计和保守地被管理,更低的重音在可消耗导致更低的维修费用。一些驱动器要求支持系统譬如流通的油为润滑油、冷却空气或水,环境尘土过滤,或计算机仪器工作。支持系统的维护可能影响驱动系统的可靠性。费用驱动器设计员将审查各个驱动系统的费用。费用合计是第一基建成本获取驱动器,费用安装和委任驱动器,费用运行驱动器,和费用的总和维护驱动器。费用使力量运行驱动器也许广泛变化用不同的地点。设计员努力符合所有系统性能要求在最低的费用合计。第8页经常超过一个驱动系统也许满足所有系统性能标准在竞争费用。更喜欢的驱动器安排是最简单,譬如一个唯