化工英文文献翻译文档格式.docx
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化工英文文献翻译文档格式.docx
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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,whileoilabove175º
Catthestartofcoking.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
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