33kv jointing manual section 3 - cablejoints.co.uk
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Section 3 I Page 1UK POWER NETWORKS 33KV JOINTING MANUAL I 2012
3 STANDARD PROCEDURES FOR PREPARING 33KV CABLES
3.1 Single-Core Copper Wire Screened Polymeric Cables3.1.1 Removing the Outer Sheath • Cleanandabradetheoutersheathwithanapprovedabrasivepaperfor150mmbeyond
thesheathremovalpoint.MarktheremovalpointoftheoutersheathasindicatedontherelevantjointinginstructionusingaChinagraphpencil.
• Forcableswithsemi-conductingoutersheaths,eithergraphiteoranextrudedlayer,extracareshouldbetakentoensurethatalltracesofconductivematerialareremoved.
• Useanapprovedtooltoremovethesheath.checkthetoolcuttingwheelissettothecorrectdepthtoavoiddamagingthecopperwirescreensbelow.
• Startingattheremovalpointmakeacircularcutaroundthecable.Cutalongthecabletothepositionofthesheathremovalpoint,andremovethesheath.
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• Removethefabricorplastictapewrapfromthescreenwireusinganapprovedknife,takingcarenottodamagethecopperwiresbelow.
• UnwindthecopperwiresandlaythembackalongtheoversheathinthepositionrequiredbythejointbeingmadeandsecurewithPVCtape.Ifpreparingforaterminationalengthofredmasticsealingtapeshouldbeappliedtotheoutersheathfollowingtheappropriateinstruction.
3.1.2 Removing the Bonded Polymeric Screen • Theapprovedbondedscreenstrippingtoolcanbeusedtoleavevariouslengthsofblack
insulationscreenfromtheoutersheathcut.Thismeasurementvariesdependinguponthetypeofjoint:
• Single-Corestraightjoints=40mm.
• Single-Corebranchjoints=80mm.
• Trifurcatingjoints=100mm.
• Potends=80mm.
• Single-Coreterminations=40mm.UNCONTROLLED
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• SmearathincoatingofSiliconegreaseovertheconductingscreenlayer.Startingattheopenendofthecable,setthetooltothecorrectcuttingdepthsothattheentirescreenisremovedwithonlytheminimumamountofinsulation.Itisessentialthatthecoreisasstraightaspossibleforthisoperationotherwisetracesofthescreenmaybeleftbehind.
• Continueturningthetooluntilitbuttsupagainstthestopposition(dependantonthescreenterminationpoint)andcontinuetoturnthetooluntilasmoothrightangledtaperisproduced.Testthetoolfirstlyontheoverlapsectionofthecoreifrequired.
• Theinsulationnowrequirespolishingsmoothwithanappropriatealuminiumoxidegritpaper(minimum150grade)untilsmoothandfreeofridges.Tofinishthisprocess,reversethepaperand'buffup'withthesmoothside.
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• Cleananddegreasetheinsulationwithanapprovedsolventwipetoremovealltracesofanyremainingloosematerial.Alwayswipefromtheopencoreendtowardsthescreenwirestoavoidcontaminatingtheinsulationwithcarbonfromtheremainingscreen.
3.1.3 Removing the Polymeric Insulation • UsetheapprovedAlroctoolandsetthe'stopgauge'totheconnectorinsertiondepth.
• Positionthetoolattheopencoreendandadjustthebladetotherequireddepth;justdeepenoughsothebladedoesnotdamagetheconductor.
• Rotatethetoolalongthecoreusingthespiralcutsettinguntilthestopgaugepreventsitfrommovinganyfurther.
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• Removethetoolandtheinsulationspiral.Carefullyremovetheremainingconductorscreenusinganapprovedknife.
3.2 Single-Core Lead Covered Cables3.2.1 Removing the Outer Serving or Sheath • Markthepositionoftheservingorsheathterminationasindicatedontherelevantjointing
instruction.
• Makeacircularcutatthismarkusinganappropriateapprovedtool.Checkthatthecutisonlythreequartersthroughthesheaththickness.
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• Nowmakealengthwisecutalongthesheathtowardsthesheathcutpositiontakingcarenottodamagetheunderlyingleadsheath.
• Lifttheedgeofthesheathandunwrapalongitslength,tearingoffatthecircularcutpoint.Theuseofagastorchmayassistthisoperationifnecessary.
3.2.2 Removing the Lead Sheath • Cleananddegreasetheleadsheathusingtheapprovedsolventwipes.Markthelead
sheathattheremovalpointasindicatedontherelevantjointinginstructionusingaChinagraphpencil.
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• Useanapprovedhackknifetomakeanindentedcircularcutaroundtheleadsheath,takingcaretoonlycutpartwaythroughthesheath.
• Cuttheleadsheathacrossfromtheopencableendtothecircularcut.Useanappropriateapprovedhackknife.TakecarenottodamagetheCopperWoventapebelow.
• Opentheleadsheathupalongthelengthofthecutandcarefullyunwraptheleadsheathagainsttheringcut.
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3.2.3 Removing the Copper Woven Tape (CWT) • UnwindtheCWTandcarefullyremoveitbycuttingitagainsttheleadsheathedgewithan
approvedknifetoleaveasmoothfinish.
3.2.4 Removing the Insulation Screen • MarkthescreenpaperswithaChinagraphpencilattheremovalpointindicatedinthe
relevantjointinginstruction.Tieatwinebinderaroundthescreenatthispoint.
• Unwrapthescreencarefullytotheterminationpointandremoveitbyneatlytearingagainstthetwinebinder.Removeanycarbonpaperbelowthescreentothesameterminationposition,followedbytwooftheinsulationpapers.
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3.2.5 Removing the Insulation Papers • Onlyremovethepapersafterfittingthebarriertubingasdescribedinsection4.1.1.
Marktheinsulationpapersatthepointofremovalasindicatedintheappropriatejointinginstruction.Usinganapprovedsharpknife,cutaroundthecorethroughthepapersandclearbarriertubetakingcarenottodamagetheconductorbelow.
• Removetheclearbarriertubebypullingtowardstheendwithagentletwistingmovement.
• Unwrapthepapersuptothecutpositionandtearoffneatlyagainstthebarriertubeedge.
• Cleananysurpluscompoundfromthecableconductorwithanapprovedsolventwipe.
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3.3 Three-Core Paper Insulated Cables3.3.1 Removing the Outer Hessian Serving or (PE) Sheath • Markthepositionoftheservingorsheathterminationasindicatedontherelevantjointing
instruction.
• Wearsuitablegloveswhileremovingtheserving.Placeawirebinderaroundtheservingattheremovalpointandscoreinfrontofthebinderusinganapprovedknife.
• Removetheservingwiththeapprovedknifeandheatfromagastorchifrequiredorinthecaseofapolyethylenesheathusetheapprovedtoolforthisoperation.
3.3.2 Removing the Steel Wire Armour • Placeawirebinderaroundthearmourwiresatthepointofremovalasindicatedinthe
relevantjointinginstruction.
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• Usinganapprovedsaw,makeacircularcutaroundthearmoursatthebinderposition.Cutthroughonlyhalfthewidthofthearmourtoavoiddamagingtheleadsheathbelow.
• Wearsuitablegloveswhileremovingthearmour.Liftandunwrapthearmourwiresafewatatimeandbreakthemoffagainstthebinderbybendingthembackwardsandforwards.
• Removethebinderandliftthearmourswithahackknifesotheyare90°tothecable.Cleanoffalltracesofbitumenfromthewiresusingagastorchandapprovedsolventwipes.
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3.3.3 Removing the Inner Bitumen Layer • Wearsuitableglovesforthisoperation.Scorearoundtheinnerbeddinglayerswithan
approvedknifeadjacenttotheverticalarmourstakinggreatcarenottoscoreintotheunderlyingleadsheath.
• Attheopencableendliftthebitumenimpregnatedtextilelayerwithaknifeandunwrapitbacktotheverticalarmourposition,tearingitagainstthescorepreviouslymade.Theuseofagastorchmayassistthisprocess.
• Applymoreheattothefinallayerofbitumenontheleadsheathandarmoursandwipeoffanyremainingtracesofbitumenwithapprovedsolventwipes.Theleadsheathandarmoursshouldbecleanandbrightafterthisprocess.
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• Applytwowrapsofblackmasticsealantaroundtheleadsheathbuttingupagainsttheraisedarmours.
• MakeamarkwithaChinagraphpencil130mmfromtheendoftheoutersheath.Wrapalengthofcoppermesharoundtheleadsheathuptothe130mmmark.
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• Laythearmoursdownoverthemastic,ensuringthatnonearecrossed,andsecurethearmoursoverthecoppermeshareawiththetwowormdriveclipsprovided.
• ApplyalayerofPVCtapetothewormdriveclipstocoveranysharpedges.Positionthearmoursealingsleeve30mmbeyondthearmouredgeandshrinkdownstartingattheleadsheathendbeforeproceedingtowardsthecableover-sheath.
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3.3.4 Removing the Lead Sheath • Cleananddegreasetheleadsheathusingapprovedsolventwipes.UseaChinagraph
penciltomarktheleadsheath430mmfromtheoutersheathasindicatedontherelevantjointinginstruction.
• Wearsuitableglovesforthisoperation.Useanapprovedhackknifetomakeacircularindentedringcutaroundtheleadsheathatthepencilmark,takingcaretoonlycutpartwaythroughthesheath.
• Fromtheopencableend,cuttheleadsheathlongitudinallytothecircularcutusingtheappropriateapprovedhackknife.TakecarenottodamagetheCopperWovenTape(CWT)below.
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• Opentheleadsheathupalongthelengthofthecutandcarefullyunwraptheleadsheathagainsttheringcut.
3.3.5 Removing the Copper Woven Tapes (CWT) • UnwindtheCWTandremovethecorefillerscarefullywiththesidecutters.
• RewindtheCWTtightlyaroundthecablecoresatthecrutchpositionforadistanceof20mmfromtheleadsheath,thencutandtieoff.Removeanysurplustapewithinsulatedsidecutters.
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3.3.6 Removing the Insulation Screen • Usinganapprovedsolventwipe,removeanysurpluscablecompoundfromthescreened
coreinsulation.
• Markthescreenpapersattheremovalpointindicatedintherelevantjointinginstruction.Tieafinewirebinderaroundthescreensatthispoint.
• Carefullyunwrapthefirst50mmofthescreen.Securetheendofthecoreinsulationpaperswithnumberedphasetapematchingthenumeralpaper.Unwindtheremainderofthescreentotheterminationpointandremoveitbyneatlytearingagainsttheappliedbinder.
• Removethenumeralpaperandonelayerofpaperbelowtothesamepointasthescreenpapers,usingthesamemethodandmarkingthecoreswiththematchingnumberedphasetape.
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Note:Itisimportanttomarkthecoreswiththecorrectphasenumbersimmediatelyaftereach numeralpaperisremoved.
3.3.7 Removing the Insulation Papers • Onlyremovethepapersafterfittingtheclearbarriertubesdescribedinsection4.1.3.
• Marktheclearbarriertubeoverthecorepapersatthepointofremovalasindicatedintheappropriatejointinginstruction.
• Usingasharpknifecutaroundthecoreandthroughthepaperstakingcarenottodamagetheconductorbelow.
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• Removetheclearbarriertubebypullingtowardstheendwithagentletwistingmovement.
• Roundingoftheconductorwithwaterpumporsimilarplierswillassistthisoperationandwillhelppreparetheconductorforinsertionintotheappropriateconnector.
• Unwrapthepaperstothecutpositionandtearoffagainsttheclearbarriertubeedge.
• Cleananysurpluscompoundfromthecableconductorwithanapprovedsolventwipe.
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3.4 Three-Core HSL Paper Insulated Cables3.4.1 Removing the Outer Serving or Sheath • Markthepositionoftheservingorsheathterminationasindicatedontherelevantjointing
instruction.
• Wearsuitablegloveswhileremovingtheserving.Placeawirebinderaroundtheservingattheremovalpointandscoreinfrontofthebinderusinganapprovedknife.
• Removetheservingwiththeapprovedknifeandheatfromagastorchifrequired.
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3.4.2 Removing the Steel Wire Armour • Placeawirebinderaroundthearmourwiresatthepointofremovalasindicatedinthe
relevantjointinginstruction.
• Usinganapproveddepthguardedorjuniorsawmakeacircularcutaroundthearmoursatthebinderposition.Cutthroughonlyhalfthewidthofthearmourtoavoiddamagingtheleadsheathsbelow.
• Wearsuitablegloveswhileremovingthearmour.Liftandunwrapthearmourwiresafewatatimeandbreakthemoffagainstthebinderbybendingthembackwardsandforwards.
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• Attheopencableendliftthebitumenimpregnatedlayerwithaknifeandunwrapitbacktothearmourcutposition.Removeitatthispoint,takingcarenottodamagetheunderlyingleadsheaths.
• Removethebinderandliftthearmourswithanapprovedhackknifesotheyare90°tothecable.Cleanoffalltracesofbitumenfromthewiresusingagastorchandapprovedsolventwipes.
3.4.3 Removing the Bitumen Layer • Openoutthethreeleadsheathscarefullyandremovethebitumen/paperlayerandfillers
fromallthreesheathsuptothepointwheretheunderarmourbeddingremains.
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• Applymoreheattothefinallayerofbitumenontheleadsheathsandwipeoffalltracesofbitumenwiththeapprovedsolventwipes.
• Theleadsheathsshouldbefreefrombitumenoncompletionofthistask.
• BuilduptheremaininginnerbeddingusingtheblackmasticfromtheThree-CoretransitionjointandtheHSLmoduletosuitthesupportring’sinnerdiameter.Fitthesupportringoverthebuilduptape,positioningit60mmfromtheupliftedarmours.
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• Wrapthelengthofsuppliedblackmasticbehindthesupportring,buttingitagainstthearmourswires.Laythearmoursdownontotheringandsecurethemwithawirebinder.
3.4.4 Removing the Lead Sheaths • Onlyremovetheleadsheathsafterfirstlyfollowingthenecessarystepsdescribedin
section4.1.5.(HSLmoduleapplication).
• Cleananddegreasetheleadsheathsusingapprovedsolventwipes.UseaChinagraphpenciltomarktheleadsheathsattheremovalpointasindicatedontherelevantjointinginstruction.
• Useanapprovedhackknife,makeacircularindentedringcutaroundtheleadsheathatthepencilmark,takingcaretoonlycutpartwaythroughthesheath.
• Cuttheleadsheathacrossfromtheopencableendtothecircularcut.Useanappropriateapprovedhackknife.TakecarenottodamagetheCopperWoventapebelow.UNCONTROLL
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• Opentheleadsheathupalongthelengthofthecutandcarefullyunwraptheleadsheathagainsttheringcut.
3.4.5 Removing the Copper Woven Tape (CWT) • UnwindtheCWTandcarefullyremoveitbycuttingitagainsttheleadsheathedgewithan
approvedknifetoleaveasmoothfinish.
3.4.6 Removing the Insulation Screen • MarkthescreenpaperswithaChinagraphpencilattheremovalpointindicatedinthe
relevantjointinginstruction.Tieatwinebinderaroundthescreenatthispoint.
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• Unwrapthescreencarefullytotheterminationpointandremoveitbyneatlytearingagainstthetwinebinder.Removeanycarbonpaperbelowthescreentothesameterminationposition,followedbytwooftheinsulationpapers.
3.4.7 Removing the Insulation Papers • Onlyremovethepapersafterfittingthebarriertubingasdescribedinsection3.1.2.
Marktheinsulationpapersatthepointofremovalasindicatedintheappropriatejointinginstruction.Usinganapprovedsharpknife,cutaroundthecorethroughthepapersandclearbarriertubetakingcarenottodamagetheconductorbelow.
• Removetheclearbarriertubebypullingtowardstheendwithagentletwistingmovement.
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• Unwrapthepapersuptothecutpositionandtearoffneatlyagainstthebarriertubeedge.
• Cleananysurpluscompoundfromthecableconductorwithanapprovedwipe.
3.5 Moisture Testing on Paper Insulated Cables • Fullpersonalprotectiveequipmentshallbewornatalltimesforthistest.
• Gentlyheattheparaffinwaxcontaineronalowheat,insertthethermometerthroughoneoftherubbergrommetsinthetopandwaituntilthewaxreachesatemperatureof125°C.
• Alwayshandlethepaperstobetestedwithgloves,asmoisturefromyourhandsisenoughtogiveapositivetest.
• Liftoutthebasketandplacethepapertapestobetestedinit.
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• Thesamplesfromthefollowinglayersshallbetested:
• Innerandouterbeltpapers.
• Paperorstringfillers.
• Innerandoutercorepapers.
• Immersethebasketcompletewithpapersintheparaffinwaxbathandnotetheresults.
• Ifthereisnoreactionfromthewaxoritfrothsslightly,thepapersaredryandthecableisfittobejointed.
• Ifthewaxfrothsexcessivelyandacracklingnoiseisheard,thepapersarewetandthecableshouldnotbejointed.
• Removetheheatfromcontainerandleavetocoolbeforemoving.
• Thewaxcanbere-useduntilitstartstodiscolourandthereisnoneedtodisposeofitaftereachmoisturetest.
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