HIGH VOLTAGE CABLE ACCESSORIES - Application, …

1 1 HIGH VOLTAGE CABLE ACCESSORIES - Application, design , installation , testing -Ivan JovanovicG&W Electric CompanyFirst detachable porcelain pothead for 4 kV systemsYear 1905 Terminations and joints from 5kV up to 345 kV for all CABLE typesYear 2015 ShanghaiDelhiTorontoSan Luis PotosiChicagoSalvadorAny sections of Transmission and Distribution lines may be undergroundApplication of Underground CablesExamples of CABLE installationDirectly buried or in conduits in trenchesExamples of CABLE installationLaid on trays in tunnels Examples of CABLE installationLaid on trays under

2 Bridges Examples of CABLE installationLaid on sea floor or river bed Submarine cablesCable accessoriesHV Power CableOutdoor terminationEquipment mount terminationJointDistribution of electrical stress in power cableConductor Conductor screenscreenInsulation screenInsulation = CABLE Endinside terminationCable conductorCable insulationCable end in accessory how does it work? CABLE conductorCable insulationCable insulation screenCable End withoutInsulation screen stripped backStress cone ground electrodeHigh stress at conductorHigh stress at insulation screenStress evenly distributedCable End withInsulation screen stripped backCable conductorCable insulationStress cone insulationEdge of CABLE insulation screenExtruded CableConductorScreenInsulationMetallicSh eathScreenWiresJacketScreenOUTDOOR TERMINATIONSGIS & Oil Immersed TERMINATIONSJOINTSUse of outdoor terminations CABLE

3 Terminations connects power CABLE to other electrical components: Overhead lines Station busesStructure-mount outdoor terminations in substationTerminationPole mount outdoor terminations on transmission Pole mount outdoor terminations on transmission line poleline poleTerminationTypical design of outdoor terminationDistribution of electrical stress in the critical areasDeflector radiusDeflector angleInterface between stress cone and CABLE insulationOutdoor TerminationSilicone Rubber Stress ConeInsulating RubberConductive Rubber (Deflector)

4 Oil sealSleeveUse of equipment mount CABLE termination GIS CABLE termination connects the CABLE to the gas insulated switchgear (GIS) Oil-immersed termination connects the CABLE to power transformerGIS terminationsGIS terminationsGIS HousingGIS TerminationTypical design of dry type GIS terminationCable supportCompression spring assemblyClamping ringStress coneEpoxy insulatorConnectorCorona shieldCableContact padEntrance housingGIS interface plateDesign considerationsPer international and domestic standards it is required that terminations and GIS gear are interchangeable regardless of who made them.

5 G&W GIS terminations meet that requirement. Joint design -GeneralHV electrodeJoint outer screenGround electrode (deflector)Shield BreakCable semi-con screenDesign -ElectricalElectrical stress inside the jointDesign -ElectricalMagnitude of electrical stress in the critical areasDeflector angleDeflector topCorona shieldUse of Joint in CABLE Bonding CABLE bonding functions: Limit CABLE metallic screen voltages Reduce or eliminate the screen losses Maintain a continuous ground path to permit fault-current return and adequate lightning and switching surge Point Bonding Lower load rating of CABLE system Zero VOLTAGE at both CABLE ends (no safety hazard)Induced current in screenInduced current in screenLoad currentLoad currentCable metallic CABLE metallic screenscreenSingle Point Bonding Induced VOLTAGE at open CABLE end (safety hazard)

6 Higher load rating of CABLE systemInduced VoltageInduced Voltagein screenin screenCable lengthCable lengthVoltage at open end VOLTAGE at open end (In US 100(In US 100--200V Max)200V Max)Cross Bonding use of shield break joints No induced VOLTAGE at open CABLE end (no safety hazard) Higher load rating of CABLE systemLocation of shieldLocation of shield--break jointsbreak jointsPaper Cables PIPEOIL orGASPAPER CABLESOUTDOOR TERMINATIONSEQUIPMENT TERMINATIONSS traight JointsStress in paper cables =DcDiLnDcyLnLnxEg2xygDcCable conductorCable insulationJoint insulationStress cone(L-L profile)

7 Formula for axial component of electrical field at the stress coneDiOil-impregnated paper CABLE Relevant forconnector designRelevant forStress cone design Retrofit of the old termination with new oneHV Transition Joints Definition: Device for connecting HV oil-impregnated paper CABLE to solid dielectric CABLE Typical application: To expand existing UG transmission network To replace ailing section of old oil-impregnated paper CABLE with new extruded cableHV Transition Joints Relatively small usage, expected to grow significantly Up to 161 kV class, many different designs in operation At 230 kV most designs are back-to-back Limited use and availability at 345 kV High pressure vs.

8 Low pressure (in regard to insulating fluid at paper CABLE side)Back-to-Back with two Insulators(CIGRE TB 415)Equipment type terminationfor paper cableGas or liquidConnectorCorona shieldsHousingExtruded cablePaper cableEquipment type terminationfor extruded cableBack-to-Back with one InsulatorGIS or Transformertype terminationGas or insulating liquidConnectorCorona shieldHousingConductor SealStress coneExtruded cablePaper cableComposite designEpoxy insulator with built-in HV electrodePaper cableStress conePaper CABLE stress coneHousingGas or liquidSpringsConnectorExtruded cableTinned Cu housingStainless steel

9 HousingExtruded cablePaper cableConnector clampStress cone(paper roll)Insulating fluidDry-Type TerminationSingle-core Transition Joint for SCFF CableBack-to-Back with One InsulatorStress cone installation with perforated Paper Roll Paper is torn along factory cut perforationsStress cone slopePaper roll(stress cone)Finalizing the stress coneCopper mesh is applied over the slopeCopper bandField InstallationFinal installation step: Oil filling of the single core 138 kV LPOF to XLPE transition joints in the fieldThree-core Transition JointTelescoping housing suitable for short manholesOil breach assembly3-C Paper cableSpider assemblyreinforced to prevent TMBP aper roll and crepe paper tape build-upDry-type GIS terminationsInstallation of 3/C Transition JointBushing of the dry-type terminationDesign Tests per IEEE 404138 kV HPFF Transition JointPipe-type cableExtruded CABLE in conduitHPFF transition jointHPFF transition

10 JointAccumulatorExtruded cableNumber of samples: 2AC VOLTAGE :1min and 24hImpulse voltageIonization factorLoad CyclingInstallation of CABLE AccessoriesExcerpt from International study on world-wide usage of HV CABLE systems(CIGRE TB 177, Section 3 Worldwide Usage of ACCESSORIES for HV Extruded Cables , Page 29) The assembly of the ACCESSORIES is the most vulnerablepart of a project involving the manufacture and installation of a new CABLE circuit. PartsHot-melt tapeConnectorSemi-con tape, 25mm wideSelf-fusing Aqua-Seal tapeSelf-fusing insulating tapeTinned Cu grounding meshSemi-con tape, 50 mm wideSand paper #150 to #600 gritString solder#18 AWG Cu wireJoint body expended onto spiral core tubeGlovesB/M and installation instructionsHeat shrinkable tubingPVC tapeInstallation Steps1.