High and extra high voltage cableswith synthetic insulation

G l o b a l e x p e r t i n c a b l e s a n d c a b l i n g s y s t e m s

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S u m m a r y

•TheevolutionofHVandEHVcableswithsyntheticinsulation 5

•Anoutlinehistoryofdevelopments 6

•ProjectengineeringforHVcablelinks 7

•ExamplesoftherangeofHVandEHVcableswithsyntheticinsulation 8

•Productiontools 9

•420 kVcabletechnology 10

•Checksandtests 11

•References 12

•Accessories 13

•Services 15

Introduction 4

H i g h a n d e x t r a h i g h v o l t a ge c a b l e s

Nexans Switzerland supplieshighandveryhighvoltagepowercablesandaccessories,opticalfibercables,opticalwave-guideandspecialcablesfortheinternationalmarket.

Nexans Switzerlandhasthreeproductioncentres:

•theBreitenbachsite

•theCortaillodsite

•theCossonaysite.

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I n t r o d u c t i o n

Nexans Switzerland isSwitzerland’sforemostcablemakerandsupplier.

Itmanufactures,distributes,fitsandinstallsacompre-hensiverangeofproductsforunderground,submarineandaerialinstallations:

•high,mediumandlowvoltagepowercables

•copperoropticalfibertelecommunicationscables

•specialcablesformanyapplications

•powerandtelecomaccessories

•connectionequipment.

Itsservicesrangefromthesupplyofcablestotheimplementationofcomplexturnkeyproducts,includingdevelopment,engineering,constructionwork,systemtechnology,laying,installa-tionandprojectfinancing.

P o s i t i o n o f Ne x a n s S w i t z e r l a n d

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T h e e v o l u t i o n o f H V a n d E H V cables w i t h synt het ic insulat ion

T h e C a b l e s

aluminiumsheath

compositesheath

Thegreaterdemandforenergyrequirestheimplementationofinstallationsdesignedtosupportincreas-inglyhighervoltageandpowerlevels.

ThisiswhyNexansSwitzerlandLtdhasdevel-opedcableswithsynthetic(ordry)insulationforvoltagesupto420 kVandcross-sectionsthatcanbelargerthan2000 mm2.

C o n d u c t o r s

Athighgradients,syntheticinsulationissensitivetothepresenceofmoisture.Itisthereforeessentialtoavoidanycontactwithwaterorsteamduringfabricationprocessesandalsoduringlineoperation.

Thecross-linkingoperationmustbecarriedoutintheabsenceofhumidity,eitheronacatenarylineinaninertatmosphere,oronahorizon-talline(MDCVprocess).

Forallcables,theexternalprotectionisprovidedbyapolyethylenesheath.Overthisinsulation,theapplica-tionofawaterproofmetallicsheath,whichalsoactsasascreen,isgenerallyrequired.

I n s u l a t i o n

Higherservicegradientsrequirebetterinsulationqualities.

Thesematerialsshouldbeperfectlyclean–thisisparticularlyimportant,astheirlong-termperfor-mancecanbeconsiderablyaffected,evenbymicro-impurities.Precautionstoensurecleanlinessshouldbetakenbothduringtheproductionofrawmaterialsandthroughouttheentirecablefabricationprocess.

S h e a t h s

Forconductorcross-sectionslargerthan1000 mm2,seg-mentedconductorsmustbeproducedtoreduceconsider-ablytheirresistancetoalter-natingcurrentbyreducingtheskineffect.

Thissheathcanbemadeofunweldedextrudedaluminumorlead,orofweldedorgluedcopperoraluminum.NexansSwitzerlandLtdusesallthesetechniqueswithcompletemastery.

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An out l ine his tor y of developments

D e v e l o p m e n t s f r o m 197 3 t o t h e p r e s e n t d ay

Sincetheintroductionofcross-linkablesyntheticinsulation,productionandcontroltechniqueshavegonethroughawholeseriesofdevelopmentsteps.

1973

1974

1976

1977

1978

1983

1986

1987

1989 – 1991

1996

1998

2006

Implementation of a cross-linking catenary line

Delivery of the first HV cables with dry insulation

Introduction of the triple- head extrusion process

Delivery of the first 150 kV extruded insulation cable

Modification of the catenary line for nitrogen cross-linking

Delivery of the first 220 kV cable with XLPE insulation

Construction and start-up of a laboratory for measuring partial discharges up to 480 kV

Production of the first XLPE Cable 220 kV with a cross-section of 2500 mm2

Production of the first 275 kV cable with XLPE insulation

Implementation of a 2nd cross-linking line for large conductor cross-sections and thick layers of insulation

Production of the first 400 kV cable with XLPE insulation

Delivery of the first 400 kV cable with XLPE insulation abroad

Delivery of the first 400 kV cable with XLPE insulation in Switzerland

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Pr oject engineer ing for HV cable l ink s

D e v e l o p m e n t p l a n

• territorialplanning

• increaseddemand

• connectionofheavyusers

• networkplan

• networkcalculation

• powerflowdetermination

• customer

Cause and nature of operations Effects Intervening parties

P r e - s t u d y p l a n

• decisiontoreinforcenetwork

• preliminaryfeasibilitystudy

• pilotstudy

• choiceofconnectiontype :underground,overheadormixed

• technicalsolutions

• customer

• Nexans

St u d y

• Impactstudy

• collaborationwithotherdepartments :engineeringoffices,industrialdepartments,etc.

• noticetomunicipalauthoritiesandlandowners

• choiceofconnectiontype :underground,overheadormixed

• drawingupofspecifications

• customer

• Nexans

P r o j e c t

• choiceofdefinitiverun

• definitionoflayingparameters

• measurementoflinelength

• preparationofcontractor’sfile

• customer

• Nexans

O f f e r s

• definitionofpossiblecabletypesorvariants

• calculationofthecross-sectionaccordingtovoltage,powerandcivilengineeringparameters

• distributionofpartiallengths

• groundingsystem

• preparationofrequestsforoffersandcontracttendersformaterialsandcontractors

• costofcivilengineeringwork

• costofinstallationandset-up,scheduleanddetails

• customer

• Nexans

Authorizations

• filefortheauthoritiesconcerned

• handlingofpossibleobjections

• buildingauthorization • customer

• inspectors

• Nexans

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E x a mp l e s o f t h e r a n ge o f H V a n d E H V c a b l e s w i t h s y n t h e t i c i n s u l a t i o n

45 kV EPR insulation

60 kV XLPE insulation

150 kV XLPE insulation

500 mm2

220 kV XLPE insulation

2000 mm2

400 kV XLPE insulation

800 mm2

HVExtrusionline

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Pr oduct ion tools

HVlaboratory

Aluminiumpress

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•extrudedcross-linkedpoly-ethylene(XLPE)insulationcableswhich,withtheprogressofthetechniquesusedinthemanufacturingofbasicmaterialsandaboveallforinstallation,haveachievedtherelia-bilitylevelrequiredforuseinextrahighvoltage(EHV)networks.

420 kV cable technology

For420 kVcables,therearecurrentlytwoalternativestotraditionalfluidoilimpreg-natedpaperinsulation :

•cableswithPPLPinsulation,consistingofthree-layerlaminatedpaperandpolypropylenetapes,formedintoribbonsandimpregnatedwithoil.

E H V c a b l e s w i t h P P L P a n d X L P E i n s u l a t i o n

PPLPinsulation,whichwasintroducedattheendofthe�0’s,isstilllimitedtocablestobeusedatavoltageof400 kVorhigher.Thisisdueontheonehandtoitsprice,whichishigherthanthepriceofpaper,andontheothertotheincreasinglygeneral-izeduseofXLPEinsulationforvoltagesupto220 kVand400 kV.

XLPE Insulation

Cross-linkedpolyethylene(XLPE)wasintroducedinthe�0’s.Itwasinitiallyusedformediumvoltagecables,butisnowusedasinsulationforextrahighvoltagecables(EHV).Itsuseatvoltagelevelsof400 kVandhigherrequires,ofcourse,sophisticat-edstate-of-the-arttechnology.Inparticular,weshouldmention :

PPLP Insulation

Forextrahighvoltage(400 kVandhigher),newtypesoftapesmadeofPPLP(PolyPropyleneLaminatedPaper)areused.Theyhavetheadvantageofcombin-ingthetraditionalapplica-tiontechnologyusedforimpregnatedpapercableswiththeexcellentelectricalanddielectricpropertiesofsyntheticinsulators.PPLPisathree-layerinsulationconsist-ingofapolypropylene(PP)sheetlaminatedbetweentwosheetsofpaper.PPimprovesthequalityoftheinsulation,whilethesheetsofpaperensurethecirculationofoilbetweenthelayers.Comparedwithpaperinsula-tion,PPLPhasahigherbreak-downstrengthandabovealllowerdielectriclosses.

P P L P a n d X L P E i n s u l a t i o n

•therigorousselectionofinsulatingandsemi-con-ductingmaterials,whichmustbeofaveryhighpuritylevel,

•thecheckingoffilteringduringapplication,

•three-layerextrusion(inter-nalsemi-conductor,insula-tionandexternalsemi-con-ductor)usingasingletool,

•theobtentionofperfectlysmoothinsulationsemi-con-ductorinterfaces,

•protectionoftheinsulationagainstthepenetrationofmoisture,

•stringentelectricalteststodetectanyfaults.

Forconnectionprojectsat420 kV,exhaustivetestshavebeensuccessfullycarriedoutforbothXLPEandPPLPcables.Themainfeaturesofthesetwotypesofcablesarecomparedbelow.

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Forallthesetasks,reli-ableandfastmeasurementequipmentisrequired.Considerableinvestmentshavebeenmadetoequipourmaterialstestlaborato-rieswiththemostmodernequipment,suchasthermalanalysisinstruments,tensilestrengthapparatus,optical

Check s and tes ts

Thematerialsusedinthecon-structionofEHVcablesaresubjectedtoverystringentqualitycontrolchecks,bothbeforeandafterproduction.Plastics,metalsandtapesallundergoelectricalresistancetestsandmeasurementsoftheirdielectricormechanicalproperties.

F r o m c h e c k s o n m a t e r i a l s . . .

After-laying tests

tocheckthequalityofassemblyofaccessoriesafterinstallationandtosimulatecableoperationandrapidlyprovideinformationoncableefficiencyafterprolongedperiodsofuse.

Accelerated ageing tests

tosimulateworkinglifeandtoprovideinformationwithinashorttimeframeontheirbehaviorinlong-termuse.

Diagnostic tests

tohighlightanydegradationphenomenainthelineinser-viceandtoprovideinforma-tionontheresidualcablelife.

Thequalityofhighvoltagecablelinksishighlydepen-dentontherigorousnatureofthetestscarriedoutonthecablesandtheiraccessories.Themorestringentthesetestsare,theloweristheriskoffailureduringoperation.

Theprincipaltestsareasfollows :

Routine tests

toevaluateproductionquality.

Type tests

tovalidateatypeofconstruction,foreithercablesoraccessories.

Special tests

undertakeninthecaseofmajordesignchanges.

. . . t o e l e c t r i c a l t e s t s

microscopes,infra-redspec-trometer,chromatograph,amongothers.

Theseexactingchecksenableustoreducetoaminimumthepresenceofundesirablematterandtoguaranteethequalityofourcables.

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Refer ences

P r e s t i g i o u s p r o j e c t s

1990 • Thefirst420 kVcablewasinstalledinSwitzerlandwithXLPEinsulationconnectedtothenetworkatthe"Bassecourt"substationoftheBerneseElectricityCompany.

ThissubstationwasconnectedtoLaufenburgandFranceby��0 kVoverheadlines.Thecopperconductorcross-sectionwas1200 mm2.

1996 • Variousinstallationsofdesalinationplantsweresetupalongthecoastofcer-tainArabcountries.Themostimportantoneamongstthemissuppliedwithcablesandacces-soriesfromNexansSwitzer-landLtd,formerlyCortaillodCossonayCable.Wesupplied�sectionsof400 kVcable,withXLPEinsulationandacor-rugatedaluminiumsheath.

1997 • NexansSwitzerlandLtd,wasawardedanimpor-tantcontractbyPowerGrid,awhollyownedsubsidiaryofSingaporePower,tosupplyandinstall2�0 kVXLPEpowercables,2'000 mm2withacor-rugatedaluminiumsheathandaccessories.Thiscontractwasthefirstofitskindtobeaward-edbyPowerGridinSingapore.Theprojectconsistedoftwocablerouteswithatotalcablelengthofabout�� km.

1998 • Cleuson—Dixenceproject,Switzerland.

Withawaterfallof1��� m,Peltonturbineof42� MW,alternatorof��.�MVA/pole,thisPowerStationsets�worldrecords.

just�.�monthsbetweentheorderdateandcommissioning.

2000 • NexansSwitzerlandlaidtwosublakelinksforSocietàElettricaSopracenerinainLagoMaggiore.Foreachlinkwithalengthof2200 m,threecablesoftheXDAluWETtype,1x�00 mm2,�0kVwereruninPEtubespreviouslyinstalledonthelakebed.

2000 • Nexanscompleteda2�0kV(�,�00 mofXAluWT,1x4000 mm2)cableinstallationanda1�2 kVinstallation(24 kmofXDFcuCuT,1x��0 mm2)fortwocustom-ersinSpain.

2004 • WhentheextensionoftheChicoasenpowerstationnearTuxtlainMexicowasdecidedtoaddafurther�generators(eachof�10MW)tothe�generatorsalreadyinserviceandbringthetotalcapacityto24�0MW(practicallyonethirdofthetotalproductioninSwitzerland),Nexansdeveloped,manufac-tured,installedandtestedthe�x400 kVcablelinks-400 kVtypePoAluWET1x400 mm2Cu-fromthetransformertothestartingpointoftheoverheadlines.Withthisproject,Nexansonceagainconfirmsitshighlevelsofexpertiseinprojectandinstallationengineering.

2004 • WhenTranselectrica(thenationalRomanianelectric-itytransmissioncompany)issuedaninternationalinvitationfortherestorationofa220 kVcircuitanda400 kVcircuit

connectedtothesametrans-formerandbuildingupacrucialpartoftheoperatingsystemofthe"PortiledeFier"(doorsofsteel)powerstation,Nexanswonthecontract.Incollaborationwithalocalcompanyandwithinanambi-tiouscompletiondate,Nexansremovedtheexistingoil-filledcablesandreplacedthemwithsyntheticallyinsulatedcableswithahigherpowerrating–400 kVtypeXDCuTAluWET,1x��0 mm2Cuand220 kVtypeXKDAlT-Tsc,1x1000 mm2Cu.

2006 • NexansSuissebegantoexpandintoChinain1���,inpartnershipwithanintegrator,withintheframeworkoftheDaYuanDuhydro-elec-tricpowerstationprojectinHunanprovince,forwhichasystemof110kVXLPEcableswassuppliedandinstalled.Furtherprojectsfollowed,inwhichNexansSuissehadthesameresponsibilitiesforthesupplyofcompletecablingsystemsandfortheon-sitesupervisionoftheinstallations:thefirst220kVXLPEcablesfortheZhengJiangpowerstationweresuppliedinearly200�;andsince200�,almost�0 kmofcables,inparticular220 kVcableswithacoppercrosssectionof2�00 mm2,forthesupplyofsub-stationsinPekinginanticipationofthe200�OlympicGames.Overaperiodof10years,nofewerthan21circuitsintotalhavebeeninstalledthroughoutthecountry.

NexansSwitzerlandLtd,manufacturedandinstalled�x400 m,400 kVXLPEcables,�00 mm2withacor-rugatedaluminiumsheathandaccessoriesforconnectingthethreetransformerslocatedintherock-cavetotheswitchingsta-tion,acrosstheRhoneriver.

1999 • ThroughNexansFrance,NexansSwitzerlandhaswonacontractforthesup-plyof�0 kmofXKDAlTcable,1x2000 mm2,1�1kVforTaiwanPower,inTaiwan.

2000 • Nexanssuppliedandinstalled�XAluWTcablecircuits,1x400 mm2and1x��0 mm2,2�0kVand�120 kVcablecircuitsonanindustrialsiteinDearbornintheUnitedStates.

2000 • Followingamechani-calaccident,thegaspressurecablesofthe1�0 kVForetaille–Chênesublakelinkingsec-tionoperatedbyServicesIndustrielsdeGenève,weredamagedinNovember1���.NexansSwitzerlandreplacedthesublakelinkwithalengthof�200 mbycablesoftheXDAluTtypeinarecordtimeof�monthsbetweentheorderandcommissioning.

2000 • Followingafireintheaccesstunneltothe"ElCajon"powerplantinHonduras,twooil-filled220 kVcablesweredamaged.Nexansreplaced2circuitswithalengthofaround1000 mbyXAluWTcables1x�00 mm2,220 kV.Thisprojectwascompletedin

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A ccessor ies

O u t d o o r s e a l i n g e n d s w i t h p o r c e l a i n i n s u l a t o r

Theconceptofthesealingendwithporcelaininsulatorhasalong-termexperiencewithpaperinsulatedcablesofmorethan�0years.Thesealingendincludesapre-moldedslip-onstresscone.

C o mp o s i t e i n s u l a t o r s f o r v a r i o u s a p p l i c a t i o n s

Thousandsofcompos-iteinsulatorshavebeeninstalledsince1��0byourcompanies,someofthemareinserviceunderverysevereconditions,atthefullsatisfactionoftheirusers.

Asanalternative,customersworldwideaskmoreandmoreforsyntheticinsulators.

Suchinsulatorsarecomposedofafibreglassreinforcedepoxytubewithtwoalumi-niumflangesandinsulatedbysiliconesheds.

Specialadvantagesarelowweight,excellentseismic,mechanicalandpollutionperformancesaswellasnoexplosionrisk.

D r y t y p e o u t d o o r s e a l i n g e n d s

to14�kV,offersmanyadditionaladvantageslike:

•noriskofleakage;noenvironmentaleffect

•easyhandling

•quickinstallation

Since20years,Nexansoffersslip-ondrytypeoutdoorsealingends,whichdon’tneedanyoilorgasfilling.Amonoblocversionavailableforvoltagesup

O u t d o o r s e a l i n g e n d s w i t h c o mp o s i t e i n s u l a t o r

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G I S s e a l i n g e n d s / Tr a n s f o r m e r s e a l i n g e n d s

TheGISsealingendsaredesignedinaccordancewithIEC�0���standard,eitheraccordingtoitem�.1forfluidfilledterminationsoritem�.2,TypeAfordrytypeterminations.

FortheconnectionofHVcablestotransformerorgasinsulatedswitch-gears,Nexansmanu-facturingprogrammeincludesadequateterminations.

J o i n t s

coppertubeandarobustPEcovering.Shieldbrake facilitiesareintegrated,factorymadeandfactory tested.

MOP :MediumOuterProtectionconsistingofasynthetic,rigidcover.

LOP :LightOuterProtectionmadeofheatshrink components.

Nexansprefabricatedhighvoltagejoints(�2-��0 kV)arebasicallycomposedofapremoldedelastomerjointbody,andanoutercasing.

Forthe�2 kVLevel,acablejointwithpremolded,factoryexpandedjointbodyisavailable.

Outerprotectionsforjointsareavailableindifferentversions :

HOP :HeavyOuterProtectioncasingconsistingofastrong

Tr a n s i t i o n j o i n t s

NexanshasdevelopedaconceptwhichguaranteesahighreliableandcompactconnectionforHVcablesofdifferenttechnologies.

WhenpaperinsulatedHVcableshavetobeconnectedtosyntheticinsulatedcables,asocalledtransitionjointisneeded.

Va r i o u s a c c e s s o r i e s a n d t o o l s

acableinstallation,suchascablescreendiscon-nectingsystems,surgearrestors,cableclamps,etc.

WherespecialequipmentsarerequiredfortheproperinstallationofHVPowerAccessories,Nexansofferssuchtools,aswellasthevar-iousaccessoriestocomplete

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Ne x a n s S w i t z e r l a n d

Nexans Switzerlandprovidesawiderangeofservicestoitscustomers,extendingfromengineeringtocablelayingandinstallation.

Workingtotheinstructionsofexperiencedteamsofengineers,highlyqualifiedfittersinstallcablesystemsallovertheworld.Layingandinstallationmaterialswhichareoptimizedineveryrespect,togetherwithmea-suringandtestinginstrumentsforeveryneed,permittheimplementationofallkindsofinstallationsunderthebestpossibletechnicalandcom-mercialconditions.

CablesdeliveredandinstalledbyNexans Switzerlandguaranteeareliableserviceformanyyears.

Basedonitsextensiveexperi-encewithlowandmediumvoltagecables,Nexans Switzerlandoffersitsclientsanexpertpartnershiptosolveproblemsandimple-mentpracticalsolutions.

A n e x p e r t a n d c o mp r e h e n s i v e s e r v i c e

Nexans Switzerland Ltd2, rue de la Fabrique • CH – 2016 Cortaillod

Phone. 41(0) 32 843 55 55 • Fax 41(0) 32 843 54 43

http://www.nexans.ch

G l o b a l e x p e r t i n c a b l e s a n d c a b l i n g s y s t e m s

2006