33kv jointing manual section 3 - cablejoints.co.uk

Section 3 I UK 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


• SmearathincoatingofSiliconegreaseovertheconductingscreenlayer.Startingattheopenendofthecable,setthetooltothecorrectcuttingdepthsothattheentirescreenisremovedwithonlytheminimumamountofinsulation.Itisessentialthatthecoreisasstraightaspossibleforthisoperationotherwisetracesofthescreenmaybeleftbehind.

• Continueturningthetooluntilitbuttsupagainstthestopposition(dependantonthescreenterminationpoint)andcontinuetoturnthetooluntilasmoothrightangledtaperisproduced.Testthetoolfirstlyontheoverlapsectionofthecoreifrequired.

• Theinsulationnowrequirespolishingsmoothwithanappropriatealuminiumoxidegritpaper(minimum150grade)untilsmoothandfreeofridges.Tofinishthisprocess,reversethepaperand'buffup'withthesmoothside.

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Section3IPage4 UK POWER NETWORKS 33KV JOINTING MANUAL I 2012

• Cleananddegreasetheinsulationwithanapprovedsolventwipetoremovealltracesofanyremainingloosematerial.Alwayswipefromtheopencoreendtowardsthescreenwirestoavoidcontaminatingtheinsulationwithcarbonfromtheremainingscreen.

3.1.3 Removing the Polymeric Insulation • UsetheapprovedAlroctoolandsetthe'stopgauge'totheconnectorinsertiondepth.

• Positionthetoolattheopencoreendandadjustthebladetotherequireddepth;justdeepenoughsothebladedoesnotdamagetheconductor.

• Rotatethetoolalongthecoreusingthespiralcutsettinguntilthestopgaugepreventsitfrommovinganyfurther.

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Section3IPage5UK POWER NETWORKS 33KV JOINTING MANUAL I 2012

• 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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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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• 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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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.


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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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33kv jointing manual section 3 - cablejoints.co.uk

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