化工英文文献翻译.docx

化工英文文献翻译.docx

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化工英文文献翻译

ThreeCommonDetailsofTheCompressorFailureAnalysis

CompressorFaultAnalysis

（1）-motorburned

Motorcompressor（hereinafterreferredtoasthecompressor）ofthefaultcanbedividedintomotorfailureandmechanicalfailure（includingthecrankshaft,connectingrod,piston,valve,cylinderheadpad,etc.）.Mechanicalfailureisoftenthemotoroverloadorstall,isoneofthemainmotordamage.

Damagemainlytothemotorstatorwindinginsulationdamage（shortcircuit）andthecircuitandsoon.Statorwindingswasfounddamagedhardtime,couldeventuallyleadtowindingburned.Windingburned,coverupsomecauseordirectcauseofthephenomenonofburning,makingthesubsequentanalysisandcauseinvestigationmoredifficult.

However,theoperationofthemotorpowerinputisinseparablefromthenormal,reasonablemotorload,goodheatdissipationandwindingwireinsulationlayerofprotection.Fromseveralaspects,notdifficulttofindreasonthanburntwindingsaresix:

（1）abnormalloadandstall;

（2）Windingshortcircuitcausedbymetalshavings;（3）contactorproblems;（4）Powerphaseandvoltageabnormalities;（5）inadequatecooling;（6）compressorvacuum.Infact,manyfactorscontributedtothemorecommonmotordamage.

1.Abnormalloadsandstall

Motorloadrequirements,includingcompressedgasloadandtheloadrequiredtoovercomemechanicalfriction.Pressureratioistoolarge,orthepressureistoolarge,thecompressionprocesswillbemoredifficult;andincreasedfrictioncausedbylubricationfailure,andextremecasesofmotorstall,willgreatlyincreasetheelectricalload.

Lubricationfailure,frictionincreases,istheleadingcauseofabnormalload.Backtothedilutedlubricatingoil,oilheat,oilcokingdeteriorationandlackofoilandsowilldisruptnormallubrication,leadingtolubricationfailure.Backtothedilutedlubricatingoil,affectingthenormalfrictionsurfacefilmformation,orevenwashedawaytheoriginalfilm,increasingfrictionandwear.Compressoroverheatingwillcausethethinningorevenhigh-temperaturecokingoil,affectingthenormalfilmformation.Systembacktotheoilwell,thecompressorshortofoil,theycannotmaintainnormallubrication.High-speedrotatingcrankshaft,connectingrodpistonspeedmovement,thereisnofrictionsurfaceprotectionfilmwillquicklyheatup,localhigh-temperaturerapidevaporationoftheoilorcoke,tomakeitmoredifficulttolubricatetheparts,afewsecondscancauseseverelocalizedwear.Lubricationfailure,localwear,theneedforgreatertorquetothecrankshaft.Low-powercompressor（suchasrefrigerators,homeairconditioningcompressor）asthemotortorque,lubricationfailureoftenoccursafterthestall（themotorcannotrotate）phenomenon,andenterthe"stall-Thermalprotection-Locked"deathcycle,motorburnonlyamatteroftime.Thehigh-powersemi-closedcompressormotortorquelarge,localwearwillnotcausestall,themotorpowerwillbewithinacertainrangeincreaseswiththeload,causingmoreseriouswearandtear,andevenleadtobitecylinder（livesecaincylinder）,rodfractureandotherseriousdamage.

Whenthecurrentstall（stallcurrent）isabout4-8timesthenormalrunningcurrent.Themomentofstartingthemotor,thecurrentreachedapeakclosetoorstallcurrent.Becausetheresistanceheatreleaseproportionaltothesquarewiththecurrent,startandstallwhenthewindingcurrentwillheatupquickly.Thermalprotectioncanprotecttheelectrodeinthestall,butgenerallywillnothavearesponsesoon,cannotpreventsuchfrequentstartingwindingduetotemperaturechanges.Frequentstartsandabnormalload,sothatthetestwindingsubjectedtohightemperaturewillreducethemagnetwireinsulation.

Inaddition,thecompressedgaswiththecompressionratiowillberequiredtoincreasetheloadandpressureincreases.Therefore,thehightemperaturecompressorforlowtemperature,orlowcompressorforhightemperature,willaffecttheelectricalloadandheat,isnotappropriate,willshortentheelectrodelife.

Windinginsulationdeterioration,ifthereareotherfactors（suchasmetalshavingsformconductiveloops,acidoil,etc.）with,itiseasytocauseashortcircuitanddamage.

2.Scrapmetalcausedbyshortcircuit

Windingmetalparticlesaremixedandgroundinsulationvalueofthelowshort-circuittheculprit.Thenormalvibrationofthecompressorrunning,andeverytimeyoustartwindingbythemagneticforceofthepipe,willpromoteinclusioninthewindingandthewindingmetalshavingsbetweentherelativemotionbetweenthemagnetwireandfriction.Sharpedgeswillscratchtheenameledmetalshavingsinsulation,causingshortcircuits.

Sourcesincludingtheconstructionofmetaldebrisleftbehindbythebrassshavings,weldingslag,compressorinternalpartswearanddamage（suchasbrokenvalves）,thefallofthemetalshavingsandsoon.Fortheclosedcompressor（includingtheclosedscrollcompressor）,themetalshavingsorbroken,wouldfallonthewinding.Forsemi-hermeticcompressors,andsomeparticleswiththegasandoilflowinthesystem,andfinallyassembledinthemagneticwinding;andsomemetalshavings（suchasbearingwearandstatorandrotorwear（sweepbore）isgenerated）willbedirectlyonthewinding.Windingmetalshavingsgatheredafterashortcircuitisonlyamatteroftime.

Needtodrawparticularattentiontothetwo-stagecompressor.Inthetwo-stagecompressor,backtothenormalgasandoildirectlybackintothefirstgrade（lowgrade）cylinder,compressedbythepressureofthecoolingtubeintothemotorwindingcavity,andthegeneralsingle-stagecompressorandthenassecond-class（highpressurestagecylinder.）Backtothegaswithoil,thecompressionprocesshasbeenskatingonthinice,iftherearebacktoliquidagain,thefirststagecylindervalvecaneasilybebroken.Brokenbythepressurevalvecanenterthewindingtube.Therefore,thetwo-stagecompressorthanthesingle-stagecompressorsaremorelikelytoelectricalshortcircuitcausedbymetalshavings.

Unfortunately,thingstendtoconspireapieceofthecompressorinthebootofaproblemwhenthenewschannelsisoftentheoilburning.Severewearofmetalsurfaceswhenthetemperatureisveryhigh,whileoilabove175ºCatthestartofcoking.System,ifthereismoremoisture（vacuumpitsnotideal,bigoilandrefrigerantwater,negativepressureairintothereturnpipeburst,etc.）,lubricantsacidmayoccur.Acidicoilwillcorrodecopperandwindinginsulationlayer,ontheonehand,itcancausecopperplatingphenomenon;ontheotherhand,thisacidcontainingcopperatomsverypoorinsulationpropertiesoflubricatingoil,providedtheconditionsforthewindingcircuit.

3.Contactorproblem

Contactsisanimportantcomponentinthemotorcontrolcircuit,oneofthebestselectionofirrationaldestructionofthecompressorcanbe.Therightchoiceaccordingtotheloadcontactsareextremelyimportant.

Contactormustbeabletomeettheharshconditions,suchasrapidcycling,continuousoverloadandlowvoltage.Theymusthaveenoughsurfaceareatodistributetheheatgeneratedbytheloadcurrent,contactmaterialshouldbeselectedtostartorstallinsuchcircumstancestopreventhighcurrentwelding.

Forsafeandreliable,whilethecompressorcontactortodisconnectthethree-phasecircuit.Copelandisnotrecommendedwaytodisconnectthetwo-phasecircuits.

IntheUnitedStates,Copelandapprovedcontactormustmeetthefollowingfour:

•contactormustmeetARIStandard780-78,"Standardforspecialaccess"provisionsoftheworkandtestingguidelines.

•Themanufacturermustensurethatthecontactsatroomtemperatureinthelowest80%ofnameplatevoltagecanbeclosed.

•Whenusingasinglecontactor,thecontactormustbegreaterthanthemotornameplateratedcurrentrating（RLA）.Meanwhile,thecontactormustbeabletowithstandmotorstallcurrent.Ifthereareotherloadsdownstreamofthecontactor,suchaselectricalfans,andsomustalsobeconsidered.

•Whenusingtwocontactors,eachcontactorratingofthesub-windingstallmustbeequaltoorgreaterthantheratingofthecompressorstallhalf-winding.

Contactscannotbelessthantheratedcurrentofthecompressornameplateratedcurrent.Sizesmallorpoorqualityofcontactcannotwithstandthecompressorstarts,stall,andlowvoltagehighcurrentimpact,single-phaseormultiphasepronetocontactbounce,thephenomenonofweldingorevenfalloff,causingelectricaldamage.

Contactjitterfrequentlystartandstopthemotorcontactor.Frequentmotorstarts,ahugestartingcurrentandheat,willaggravatethewindinginsulationaging.Eachtimeyoustart,themagnetictorquetothemotorwindingshavesmallmobileandmutualfriction.Ifthereareotherfactorswith（suchasmetalshavings,poorinsulationoil,etc.）caneasilyleadtoshortcircuitsbetweenwindings.Thermalprotectionsystemisnotdesignedtopreventsuchdamage.Inaddition,thejitterofthecontactorcoileasytofailure.Ifyouhavecontactwiththecoilisdamaged,pronetosingle-phasestate.

Ifthesmallselectionofthecontactor,thecontactarc,andcannotaffordtoopenduetothefrequentinstabilityofcirculatoryarrestorheatgeneratedbythevoltagecontrolloopmaybeweldedtogetherorfromthecontactframeintheloss.Weldingofthecontactswillhaveapermanentsingle-phasestate,theoverloadprotectiondevicecontinuouslycycleonandoff.

Needstobestressedisthataftertheweldingcontactor,disconnectthecompressorcontactorpowerdependenceofallthecontrolloop（suchashighandlowpressurecontrol,hydrauliccontrol,defrostc