电缆电缆英语课程1317英语版.docx

电缆电缆英语课程1317英语版.docx

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电缆电缆英语课程1317英语版

LessonThirteen

PowerCable（Ⅰ）

Inthepowersystem,powercableandoverheadconductorareallusedintheenergytransmissionanddistributionline.Theconstructioncostofcablelineisgenerallyhigherthanthatofoverheadline,butinsomeparticularcases,someprojects,suchaspowertransmissionacrosslargeriverorstraitanddirectintroductionofsupertensionlineintothecenterofcityandindustrialarea,canonlybefulfilledbyusingcableline,whileitisnoteasyorcompletelyimpossibletofulfiltheseprojectsbyoverheadline.Withthedevelopmentofindustry,theuseofcableisincreasingyearbyyearinproportiontowholetransmissionline.Thepopularityofcablereflectsnotonlythespeedanddepthofthedevelopmentofpowerindustrybutalsothedegreeofmodernizationofcityconstruction.Withtherapiddevelopmentofnationaleconomy,theuseofpowercableisgrowinginpopularity.

Whencomparedwiththeoverheadline,thecablepossessesthefollowingfeatures:

1）Itcanbegenerallyburiedundergroundorinstalledindoors,inductandtunnel,shortdistancebetweencables,withoutusingthetower,takinguplittlespace,withoutoccupyingspaceaboveground.

2）Itislesseffectedbyweatherconditionandsurroundingenvironment.Stabletransmissionpropertyandreliability.

3）Itcanbedevelopedtowardsupertensionandlargecapacityonmorefavorablecondition,suchascryogenicandsuperconductivecable.

Therefore,thepowercablesareoftenusedinurbanundergroundnetwork,leading-outlineofpowerstation,powersupplywithinindustrialandminingenterprisesandunderwaterpowertransmissionacrosstheriverandstrait.

Themainconstructionelementsofpowercableare:

conductor,insulationandsheath.Thepowercableshouldbeprovidedwiththeshield,except1-3kVproduct.Variouskindsofintermediatejoints,terminationsandtheotheraccessoriesarealsomountedinthecableline.

Thecableanditsaccessoriesshouldfulfilthefollowingrequirements:

1）Theycansustainlongtermoperatingvoltageinthenetworkandvariousovervoltage,suchasoperatingovervoltage,atmosphericovervoltageandfaultovervoltage,whichfrequentlyhappeninoperation.

2）Theycanreliablytransmitnecessarypower.

3）Theyhavegoodmechanicalstrength,bendingpropertyandanti-corrosionproperty.

4）Theyhavelongservicelife.

Therearemanykindsofpowercable.Themiddleandlowvoltagecable（35kVandbelow）:

Mass-impregnatedpaperinsulatedcable

Non-drainingcable

PVCinsulatedcable

PEinsulatedcable

XLPEinsulatedcable

Naturalrubberinsulatedcable

EPRinsulatedcable

Highvoltagecable（110kVandabove）:

Self-containedoil-filledcable

Pipe-typeoil-filledcable

PEinsulatedcable

XLPEinsulatedcable

Inthedevelopmentofcable,itisthefollowingimportantinnovationsintheconstruction,thatmadeitpossibleforthecabletogrowupfromlowvoltagetohighvoltage.Firstly,in1914,theshieldedcableconstructionwasputforwardinGermanytoimprovethedistributionofelectricfieldinsidecable.Secondly,in1924,theconstructionofoil-filledcablewasadvancedinItaly.Inthiskindofconstruction,theinsulatingoilincableandtheoiltankwereconnectedtogethertomaintainthepressureincableandremovethegasgap,insuchcase,thepartialdischargeininsulationwassuppressedtoenabletheoperatingvoltageofcabletorisetoabove110kV.Thirdly,sincetheseventiesofthetwentiethcentury,theextrudedinsulationcablehasbeendevelopedtohighvoltagegradeduetotheapplicationoftripleextrusionanddrytypecrosslinkingaswellastheproductionofsupercleaninsulationmaterial.

In1958,ourcountrybegantrial-producingtheoil-filledcable.In1964,the66kVoil-filledcablewasmadeandputintooperationatDalianSecondPowerPlant,thenthe110kV,220kVand330kVoil-filledcablesweremanufacturedoneafteranotherandusedatLiuJiaXiaPowerStationandsoon.Finally,thehightensioncablesenteredthecityastheundergroundpowertransmissionline.Developedintheearlyeightiesofthetwentiethcentury,the500kVoil-filledcablewasusedinJinZhou-LiaoYang500kVlineforconnectingthetransformerandoverheadlineandapprovedbystateauthorities.Inrecent10years,therehasbeenrapiddevelopmentintheproductionofXLPEcableinourcountryandabouttwentydrytypeXLPEcrosslinkinglineshavebeenintroducedfromabroad,thusmakingpossibletheproductionof220kVXLPEcable.

Withthedevelopmentofpowerindustry,itisrequiredofpowercable,thatitsoperatingvoltagewillbegettinghigherandhigherandthetransmissioncapacitywillbegettingmoreandmore.Thehighestoperatingvoltageofpowercableis500kV.Theconstructiontypeofcableisasfollows:

Self-containedoil-filledcable

Pipe-typeoil-filledcable

XLPEinsulatedcable

Gascompressioncable

Cryogeniccable

Superconductivecable

ThewoodfiberpaperandPPLPpaperareusedasinsulationofoil-filledcable,impregnatedinsyntheticoil（Dodecylbenzene）.Now,the500kVXLPEinsulatedcableandgascompressioncableareonlyusedasleading-outlineatpowerstation.Thetrialproductionof750kVcablewascarriedonwithsuccessandthelongtermageingtestwasqualifiedat1100kVvoltagegradeabroad.

PPLPisthepolypropyleneandwoodfiberlaminatedpaperwiththethicknessratioofpolypropylenebetween30%-50%.Whenusedasinsulationofsupertensionoil-filledcable,PPLPpossessesthefollowingadvantageincomparisonwithwoodfiberhighvoltagecablepaper:

lowdielectricloss,highdielectricstrength,stablethermalandmechanicalproperties,soitisanewandpromisingmaterial.ThevoltagegradeofPPLPinsulatedoil-filledcablehasreached500kV,longtermtesthaspredicteditsservicelifeover40years.

LessonFourteen

PowerCable（Ⅱ）

Mass-impregnatedpaperinsulatedcable

Mass-impregnatedpaperinsulatedcablehasbeenusednearlyforacentury.Itisanimportantchapterofthedevelopmenthistoryofpowercable.Itundertookanarduoustaskofpowertransmissionanddistributionfromlowvoltagetohighvoltage.Theuseofmass-impregnatedpaperinsulatedcablehasthelongesthistoryanditsconsumptionisthelargestofallcables.Itwasfamousforitsadvantageofhavingthelongservicelifeandhighthermalstability.But,withthelapseoftimeandthecontinualappearanceoforiginalmaterials,itsdisadvantage,suchascomplicatedmanufacturingtechnology,longproductioncycleandlargeequipmentinvestment,werethoroughlyexposed,thereforeitgraduallyfadedoutfromthecablemarketinthevoltagerangebelow35KV.Now,exceptafewstate-ownedcablefactories,whichusedtoproduceagreatnumberofpaperinsulatedcables,continuetohaveitsmanufacturingequipment,somepresentleadingcablefactories,whichhavebeenestablishedsincethepolicyofreformandopeningofourcountrytotheoutsideworld,havenosuchequipmentatall.

But,itshouldnotbeinterpretedasasignalthatthepaperinsulatedcablehasalreadybeeneliminatedcompletely.Norshouldithastilyconcludethatsuchcablelostitsusevaluelongago.Itisstillfartooearlytopredictthatsuchcablewillsoonquitthehistoricalstage.Becauseinthehighvoltagearea,suchas110KV,220KV,330KV,andmuchmore500KV,thepaperinsulatedoil-filledcablestillhasapieceofland.Justinthemiddleoftheninetiesoflastcentury,theHongKongChinaLight&PowerCompany,limitedhadinstalledagreatnumberofpaperinsulatedoil-filledcablesatNewAirportontheLantaoIsland,aconsiderablepartofthemweresuppliedbymainlandwithgoodoperationsofar.Atthattime,theHongKongChinaLight&PowerCompany,Limitedwasfacedwithtwoalternatives,eithertousethepaperinsulatedoil-filledcablehavinggoodthermalstability,butcomplicatedmaintenance,ortheXLPEinsulatedcablewithmaturetechnologyandeasymaintenance.Afterweighingtheadvantagesanddisadvantages,theyfinallymadetheirdecisiontousetheoil-filledcable.Theactiontakenbysuchanauthoritativepowercompany,showedthatitwasawisedecisiontousetheoil-filledcableinthehighvoltagearea,ifinthelightofstability.Thereisnodoubtthatoil-filledcablecancertainlyhelpalotintheprojects,suchaslargepowerstation,damandpowertransmissionwithinbigcity.Evenintheareabelow35KV,despitethefactthattheplasticextrudedcablehasalreadydominatedthemarket,thepaperinsulatednon-drainingcablecanstillfindfavorincustomers’eyes,becauseitispeculiarlysuitableforuseinverticalinstallationandtropicalarea.

Themass-impregnatedpaperinsulatedcablescanbedividedintotwotypes:

commontypeandnon-drainingtype（MIND）.Theyareidenticalintheirconstruction,butwithdifferentimpregnants.Theywerepopularlyusedatvoltageof35KVandbelow.Themultiple–corecablewithvoltageof10KVandbelowoftensharesacommonmetalsheath（leadorAL）,itisso-calledbeltedcable;forthecablewithvoltageof20KV~35KV,ifeachinsulatedcorehasalead（AL）sheath,itisso-calledseparatedlead（AL）sheathedcable;ifeachinsulatedcoreisprovidedwithaseparatescreen,butwithacommonmetal（leadorAL）sheath,itisso-calledindividuallyscreenedcable.

Thecommonmassimpregnantisamixtureofcolophonyandlowvoltagecableoil.Thenon-drainingimpregnantisoftenamixtureoflowvoltagecableoilandsomeplastics（suchaspolyethylenepowder,polyisobutylenecompound）aswellasearthwax.Thepetroleumproductorthesyntheticoilareusedasthelowvoltagecableoil.

Thecommonmassimpregnantwillflowevenatlowoperatingtemperature.Whent