地铁客运服务英语课件第六单元教材课件moban.ppt

地铁客运服务英语课件第六单元教材课件moban.ppt

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PartBPartBPartEPartEPartDPartDPartAPartAPartCPartCUnit6PowerSupplySystem地铁供电系统地铁供电系统PartBPartBPartEPartEPartDPartDPartAPartAPartCPartCTranslatethefollowingwordsintoEnglish:

低低低低压压配配配配电盘电盘_综综合合合合监监控系控系控系控系统统__通信系通信系通信系通信系统统_自自自自动动售售售售检检票系票系票系票系统统_PartBPartBPartEPartEPartDPartDPartAPartAPartCPartC（BrownisaCanadianEngineer.HeishavingaconversationwithasubwaystaffmemberJohn.）Brown:

Howmanycomponentsdoespowersupplysystemhaveinthesubway?

John:

Basicallywehavecityelectricity,LVdistributor,UPS,computercontrolledSmartUPSandsubsystems.Brown:

Whydoesthesignalsystemhavetwopowersupplies?

John:

Thisisbecausesignalsystemarethelifelineofsubwayoperation.Outofpowermaycausehugeaccidents,casualtiesandeconomicloss.Twopowersuppliescanensureitsreliablerunning.Brown:

Well,LVdistributorhastwopowersupplies,isitbecauseofthesamereason?

John:

Absolutely.Brown:

WhatisUPS?

John:

ThefullnameofUPSisUninterruptiblePowerSupplywhichimprovesthereliabilitiesofsubwaypowersupplies.Brown:

WhatisthemodeofpowersupplyfortheMetro?

John:

Usuallytherearetwomodes,thirdrailandoverheadwires.Itisdifferentfromcitytocity.Brown:

Isee.Ihavelearnedalottoday.PartBPartBPartEPartEPartDPartDPartAPartAPartCPartCPartBPartBPartEPartEPartDPartDPartAPartAPartCPartCPartCTextPartCTextAlthoughtheinitiallinesofwhatbecametheLondonUndergroundusedsteamengines,mostmetrotrains,bothnowandhistorically,areelectricmultipleunits,withsteelwheelsrunningontwosteelrails.Powerforthetrains,referredtoastractionpower,iscommonlysuppliedbymeansofasinglelivethirdrail（asinNewYork）at600to750volts,butsomesystemsusetwoliverails（notablyLondon）andthuseliminatethereturncurrentfromtherunningrails.Overheadwires,allowinghighervoltages,aremorelikelytobeusedonmetrosystemswithoutmuchlengthintunnel,asinAmsterdam;buttheyalsooccuronsomethatareunderground,asinMadrid.BostonsGreenLinetrainsderivepowerfromanoverheadwire,bothwhiletravelinginatunnelinthecentralcityandatstreetlevelinthesuburbanareas.SystemsgenerallyuseDCpowerratherthanAC,eventhoughthisrequireslargerectifiersforthepowersupply.DCmotorswereformerlymoreefficientforrailwayapplications,andonceaDCsystemisinplace,convertingittoACisgenerallyconsideredtoolargeaprojecttocomplete.PartBPartBPartEPartEPartDPartDPartAPartAPartCPartCPartBPartBPartEPartEPartDPartDPartAPartAPartCPartCnn1.Pleaselisttwomodesofpowersupplyfor1.Pleaselisttwomodesofpowersupplyformetro.metro.nnthirdrailandoverheadwiresthirdrailandoverheadwiresnn2.Pleaselistthenameofeachpartofthe2.Pleaselistthenameofeachpartofthepowersupplysystem.powersupplysystem.nnThirdrail:

alivethirdrail,operationalrailThirdrail:

alivethirdrail,operationalrailoverheadwires:

wires,pantographoverheadwires:

wires,pantographnn3.Whatsthecharacteristicofpowersupply3.Whatsthecharacteristicofpowersupplysystem?

system?

nnTractionpowerissuppliedbyTractionpowerissuppliedbymeanismeanisofaofasinglelivethirdrailoroverheadwires.singlelivethirdrailoroverheadwires.PartBPartBPartEPartEPartDPartDPartAPartAPartCPartC