Gas Insulated Switch Gear ABB Presentation

GAS Insulated Switchgear

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Gas insulated
Switchgear (GIS)
General

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Introduction
Atnormalatmosphericconditions,theinsulationdistancesdetermine
themainsizesoftheclassicdistributionsubstation.
Foralongtime,thedevelopmentinsubstationconstructionconcentrated
simplyincombiningexistingdevicestoobtainthearrangementmore
adequateforexploitationandsupplysecurity.
Ontheotherhand,theincreasingneedstoconveyelectricenergy,at
highervoltages,towardstheregionswithgrandpopulationdensity
andtheindustrialcentres,causesgreatdifficultiesduetothesizeof
theinvolvedinstallations.
Officialprescriptionsandthetown-planningrequirementscomplicatethe
construction.

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Introduction
Duetothetroublescausedbypollutionininsulators,thetendencyis
tobuildindoorsinstallations.
However,thecostincreasinginconstructionleadstoreduce,asmuchas
possible,thedimensionsoftheinstallation.
Hence,tosolvethisproblem,smallerinstallationsareneeded,which
shouldalsocomplythefollowingrequirements:
Theyshallbeinsensibletoclimaticinfluences.
Theycanberaisedoutdoors,insideabuildingorunderground.
Theyrequirereducedmaintenance.
Theyaresilent.
Theyshouldnotgenerateradioelectricdisturbances.
Theyshallnotimplydangerforthenearbypopulatedzones.

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Introduction
Asasolutionforthisproblem,metal-enclosedinstallationswithSF6
insulationareused.

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Introduction
Inthissystem,thepartsofthemaincurrentcircuit(suchasthecircuit
breaker,thedisconnector,thebuses,etc.)aremechanically
integratedinasetthatcanbecalledcouplinggroup.
Thecompactmanufacturingandthehighlydevelopedwiring
techniqueallowthefreedeterminationofthesite,andensurethe
independenceregardingclimaticconditions.
Somepossibleapplicationsofthisveryhighvoltagemetal-enclosed
stations:
Maindistributionstationsinsidecities.
Maindistributionstationsforimportantcustomers.
Maindistributionstationsinzoneswithpollution,salt,orriskof
explosion.
Maindistributionstationswithspecialcharacteristics(underground
stations,sheltersofreinforcedconcrete,etc.).
Classicinstallationexpansion,incaseofreducedspace.
Mobiletransformationstations.

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Introduction
Thegas-insulatedsubstationsutilizethesameswitchgearof
conventionalsubstations,butwithdesignandcharacteristicsslightly
different.
Thewholestationisintegratedinsideagroundedaluminiumenclosure
filledwithSF6,whichensurestheinsulationtoground.
Diagramofa220kVgas-insulatedsubstation.

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Introduction
Fig.presentssomebasiclayoutsoftheassortedtypesofgas-
insulatedsubstations,whichwillvaryaccordingtotherequirements
ofeachinstallation

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Advantages of SF
6-insulated installations
Reducedrequiredspace
Outlookcompatiblewithsurroundingswithoutalteringarchitecturalor
naturalbeauty.
Reducederectionandassemblytimes.
Theinstallationsaredielectricallyandtotallytestedin-site(unlike
conventionalsubstations).
Reducedmaintenanceandconsequently,lowercosts.
From30kVto500kVtheymightresultcheaperthanconventional
units.
Upto170kV,tripolardesignisused(threephasesinthesame
casing).Foruppervoltages,eachphaseisseparatelyinsulated,
enclosedandcompartmentalized.

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Surge arresters
Whentheconnectionwiththenetworkisperformedthroughan
overheadline,thesurgearresterislocatedattheentranceofthe
gas-insulatedsubstation.
ThesurgearrestercanbeconventionalorSF6-insulated.
Inthislastcase,ifdistancesinthesubstationarehigherthanthe
protectiondistanceofthesurgearrester,itisconvenienttoinstall,
besides,asurgearresterinsidethemetal-enclosedsubstation.

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Surge arresters
Whenthesubstationisconnectedtothenetworkthroughahigh
voltagecable,itisadvisabletointegratethesurgearresterinsidethe
substationcasing.
Thisadvicebecomesmandatoryiftheconductorislongerthan50m,or
ifthesubstationoccupiesaveryextendedsurface.
Thesurgearrestersarealsoencapsulatedandtheirdischarge
voltageislowerthaninconventionalarresters,duetothelackof
pollutionandtothedirectcouplingtothebreakingdevice(not
necessarilyconnectedtotheline).

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Surge arresters. Metallic casing
Thecylindricalmetalliccasingiscomprisedofconcentricsheetsof
aluminium,weldedasatube.
Theclampsarealsoaluminiumpieces.
Theratedvaluesoffillingpressure(Pats)fortheSF6are420540kPa
at20ºC.
Ifthesurgearresterneedsaccessories,suchasgasvalves,
densimeterormanometer,dischargecounterorbreakingdisks
(pressurelever),theywillbemountedinitstop.
Asmentionedbefore,upto170kVthethreephasesarelocatedin
thesamecasing.Foruppervoltages,eachphaseismountedin
individualcompartments.

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Surge arresters. Metal-Oxide Disks
Thesurgearrestersinsulatedin
SF6,alikeconventionalarresters,
areconstitutedbycolumnswith
severalpiledupmetal-oxidedisksof
variableresistance.
Thesecolumnsareconcentrically
mountedinthemetalliccasing.

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Surge arresters. Metal-Oxide Disks
Theflatcontactsurfacesaremanufactured
withaconductivemetalliclayerandthe
cylindricalsidesareelaboratedwitha
hermeticlayerofpassivatedcrystal
(neutralmetalthatpreventscorrosion).
Thisdesignallowsthatthediskscanbein
directcontactwiththeSF6,which
increasesthecapabilityofheatevacuation
during,forexample,repetitivestrong
discharges.
Toavoidtheexcessivesizeofsurge
arrestersforvoltagesupperthan170kV,
thedisksarepiledupinthreecolumns,
formingatriangle,electricallyconnectedin
series.
Eachcolumnconsistsoffibreglassaxles
andspringsthatcompressthedisks.

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Surge arresters. Metal-Oxide Disks
Adevicethatevenlydistributesthevoltageamongalldisksislocated
inthetopofthecolumns.
Fig.comparesarresterswithandwithoutsuchdevice.

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Disconnectors
Slide-indisconnectorsareusedingas-insulatedsubstations,capable
tobreakthecapacitivecurrentsthattakeplaceduringthecoupling
manoeuvresintheinstallation,andtobreakcommutationcurrents
causedbychangesinthebusesconfiguration.
Tooptimisetheoperationofthedisconnectorsindifferentpointsof
thedistributionstation,theactivepartsareencasedseparately,
reducingtominimumthenumberofflangedjoints.

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Disconnectors
Thedisconnectorconsistofthemaincontact(6)andthecasingof
theslidingcontact(9),inwhichinteriorislocatedthecouplingofthe
slidingcontact(12).
Theconductorisconnectedtobothcontactsbysheetcontacts.
Theslidingcontact(12)istripolar-operatedbythedrive(10),which
compriseslever,pitmanandinsulatingrotarybar(8)withmotorised
drive.

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Disconnectors
Eachdisconnectorcanincludeoneortwoearthingswitches(4).
Thereceivingearthingcontacts(5)aremountedinthecasingsofthe
mainandslidingcontacts(6,9).
Thegascompartmentofthedisconnector,usuallyjointedtoother
partsoftheinstallation,isenclosedinthecasing(3)andsurveyedby
meansofdensimeters(7).
Thedischargingplate(1)protectsthecasingagainstexcessive
overpressure,andtheabsorber(2)keepsthegasdry.

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Disconnectors
Eachdisconnectorhasaspyholetoobservethepositionofthe
contactsandallowscheckingtheircondition.
Thedisconnectorsshallbeopenedsolelyforinspectionworks.
Formaintenanceorexpansionoftheinstallation,thedisconnectors
canbemechanicallyinterlockedinthedesiredendedposition,and
lockedbymeansofapadlockoranyotherlockingdevice.
Theinterlockingwithcircuitbreakers,otherdisconnectorsorearthing
switchesiselectric.

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Disconnectors
Theremightbe
variationsinthe
design,linearor
angular,according
totherequirements
intheinstallation
configuration.
Fig.showsdifferent
possibilities.1. Casing
2. Insulator
3. Fixed contact
4. Mobile contact
5. Mobile contact casing
6. Fixed contact
7. Insulating rotary bar
8. Drive
9. Earthing switch (optional)
1. Fixed contact
2. Fixed contact casing
3. Mobile contact
4. Insulating rotary bar
5. Support of the contact
6. Drive
7. Insulator
8. Casing

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Earthing switches
Theearthingswitchescanbeadaptedto
diversecomponents,andaccordingtothe
layoutandthebuyerspecifications,canbe
mountedinanypointoftheinstallation,as
maintenanceearthingswitchesorasfast-
closingearthingswitches.
Lockingboltsprovidedwithpadlocksorsimilar
devicesensurethelockinginthedesired
position.
Themaintenanceearthingswitchesendure
short-circuitcurrentsintheclosedposition.
Theycomprisethecasingofthemechanism
withslidingcontactincorporatedandcontact
barbyleverandpitman.
Theswitchingiseitherunipolarbyhandor
tripolarbymotor.

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Earthing switches
Thefast-closingearthingswitchesareusedtogroundpartsofthe
installationundersupplynormalconditions.
Theirtripolarswitchingmechanismiscapabletomakeshort-circuit
currents.
Duringtheclosingmanoeuvre,theclosingspring(10)istightenedby
thelinkage(6)andthemanoeuvringlever(5),throughamotorised
drive.

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Earthing switches
Oncetightenedthespring,thetrigger(11)releasesthemanoeuvring
lever(9),andthemanoeuvringbar(2)closesrapidlybymeansofthe
couplingbar(8),theaxleandthepitman.
Thereceivingcontact(1)isastandardisedpieceofthesedevices,as
wellasinthemaintenanceearthingswitchesinthecorresponding
device.

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Circuit breakers
Likewiseinconventionalinstallations,theautomaticcircuitbreakers
ensurethebreakofshort-circuitcurrents.
Thegasinthebreakingchamberisinjectedbymeansofapiston
mechanicallycoupledtothemobilecontact,whichcompressthegasata
pressuretwoorthreetimeshigherthanthesupplypressure,inorderto
generatetheblowing,enlargementandcoolingofthearc,andits
extinctionatthezerocrossingofthecurrentwave.
Theycanbearrangedhorizontallyorverticallytominimizethesizeof
thesubstation.
Thenumberofchambersdependsontheratedvoltageandthe
breakingcapacityofthecircuitbreaker.
Thedrivecanbemechanicalorhydromechanical.

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Circuit breakers
Fig.showsacircuitbreakerinhorizontalpositionfor245kV,with
mechanicaldrive.
Inthepoleenclosure(2),thetruncated-coneinsulator(1)supportsthe
mainfixedcontact(5),whichisjointedtotheexpansioncasing(3).
Theothertruncated-coneinsulator(1)carries,initsverticalaxis,a
clampcontact(8)thatlinksthebreakingdevicetothefixedpartofthe
installation.

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Circuit breakers
Thisallows,withinspectionandrevisionpurposes,tounplugand
extracttheactivepartfixedtothelidbymeansoftwocylindrical
insulators(9).
Theenergyrequiredtogeneratetheextinctionfluxintheblowing
cylinder(7)andnozzle(6)isconveyedbythegear(14)andthe
insulatingpitmanoftraction(11).
Thedensimeter(4)surveysthegascompartmentofthepole,
protectedagainstexcessiveoverpressurebyadischargingplate
(12).

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Circuit breakers
Thefollowingfigure
showsacircuitbreaker
inverticalpositionfor
245 kV with
hydromechanical
drive.1. Hydromechanical drive, 2. SF6, 3. Breaking chamber
4. Casing, 5. Input feeder connection,
6. Output feeder connection

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Circuit breakers. Breaking chamber1. Main fixed contact, 2. Arc fixed contact
3. Arc mobile contact, 4. Main mobile contact.
5. Nozzle 6. SF6

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Circuit breakers. Hydromechanical drive High pressure
Low pressure

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Instrument transformers for GIS
ThemeasurementandprotectiontransformersforSF6-insulated
substationsaredifferentfromconventionaltransformersintheir
especialconstructivecharacteristics.
Fig.showstheshapeandlocationofvoltageandcurrenttransformers
inanSF6-insulatedsubstation.

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Current transformers
Theone-phasecurrenttransformersarebushingtype,withring-shaped
coreandtoroidalsecondarywinding.
Thecoresareexternallystickonthemetallicenclosure,outsidethe
SF6container,separatedfromthehighvoltageregionbyacylindrical
shield. 1. Insulator
2. Terminal box
3. Support of core
4. Casing
5. Cores
6. Main conductor (primary)

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Current transformers
Thesecondarywindingislocatedabovethecoreandconnectedtothe
terminalbox.Thecommutationofthetransformationratioispossible
throughthesecondarywinding.
Thestressescausedbytheinneroverpressureofthegasandforthe
currentcirculatingthroughthecasingareconveyedbythetractionbars.
Themaximumnumberofcoresthatcanbeplacedinsidethecasing
dependsonthetransformationratioandonthecharacteristicsofthe
cores. 1. Insulator
2. Terminal box
3. Support of core
4. Casing
5. Cores
6. Main conductor (primary)

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Voltage transformers
Thevoltagetransformerisone-phase
(phase-to-groundconnection)andcan
beinductiveorcapacitive.
IntheInductivevoltagetransformer,
theactivepartsareenclosedina
casingofmeltedaluminium.
Thestratifiedcoresupportstheprimary
andsecondarywindings. 1. Terminal box
2. Primary winding
3. Secondary winding
4. Core
5. High voltage terminal

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Voltage transformers
Theinsulationamongthelayersofthe
primarywindingiselaboratedwithplastic
sheets,andtheinsulationbetweenthe
primarywinding,coveredbyashielding
electrode,andtheexternalcasingisSF6.
Thevoltagetransformerisaccommodated
inanindependentgascompartment,
separatedformtheothersbyaconical
fasteninginsulator.

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Voltage transformers
Thehighvoltageconnectionisperformed
throughaninterconnectionbolt.
Theoppositeextremeoftheprimary
winding,connectedtoground,aswellas
theextremesofthesecondarywindings,
arecarriedinagastightfashionoutofthe
transformercasing,andjointedtothe
terminalsfortheexternalconnectionsof
theconnectionbox.

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Voltage transformers
Inthecapacitivevoltagetransformer,thecoreandthewindingsare
replacedbyacapacitivedivider,createdbetweenthemetalliccasing
andtheconductor.
Thecapacitivedivideriscoupledtoanoperationalamplifierthat
providesthesignallingtotheprotectionandmeasurementdevices.

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AGENDA
INTRODUCTION
ADVANTAGES OFSF
6-INSULATEDINSTALLATIONS
SWITCHGEAR CHARACTERISTICS
Surgearresters
Disconnectors
Earthingswitches
Circuitbreakers
Instrumenttransformersforgissubstations
TESTS

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Tests
Thetypetestsperformedinthegas-insulatedswitchgear
(disconnectors,circuitbreakers,surgearrestersandprotectionand
measurementtransformers)followthesamestandardsandguidelines
thanconventionalswitchgear.
However,additionaltestsshallbecarriedout,basedonthestandard
IEC62271-203“Gas-insulatedmetal-enclosedswitchgearforrated
voltagesabove52kV”,suchas
thegastightnesstestand
thetestofinternalfailurearc.
Besides,everymanufacturerhasitsowntestingprotocolnoprescribed
inthestandards

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Gas tightness test
Thistestisperformedtoverifythatthemetal-enclosedsubstation
complieswiththepermittedvalueofgaslosses,whichshallbelower
than1%.
Thetestisdividedinseveralsteps:
Individually,theporosityofthealuminiumcasingisverified,fillingit
withhelium.
Withthesubstationtotallyassembled,theairisextracteduntila
pressureinferiorto100Paisreached.Then,thepossiblepressure
risesareobserved.
Finally,thesubstationisfilledwithSF6,inthenominalconditionsof
theinstallation,andtestsareperformedinordertoverifythe
pressurespecificationsofeverygasketandwelding.

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Test of internal failure arc
Thetestconsistinverifyingthatthemetal-enclosedinstallationcomplies
thedemandsofendurancetoarc,evenintheunlikelycasesofafailure
withthehighestshort-circuitcurrentpossible.
Undertheseconditions,thefollowingrequirementsshallbesatisfied:
Nometal-enclosedpartshallexplode.
Thedamagesshallbeexclusivelyrestrictedtothegascompartment.
Thearcshouldnotpuncturetheshieldingduringthefirststepof
protection.