Gas Insulated Switchgear ELK-0for stations up to 170 kV, 4000 A, 63 kA

2

General 3

Set-upof a substation 4-5

The system and its components 6-17

Busbar with combined

disconnector and earthing switch

Circuit breaker with current transformer

Cross unit with combined

disconnector and earthing switch

Make-safe earthing switch

Current and voltage transformer

Cable sealing end

SF6 outdoor bushing

Supplementary modules

Control cubicle

Transport, Installation 18-21and maintenance

Version examples 22-33

Double busbar

Single busbar

H-circuit

11/2-breaker method

Mesh substation

Technical data 34

Content

Since the presentation of the firstSF6-insulated 110-kV-switchbay inthe year 1965, ABB has been amongthe pioneers of this technology.

Nowadays the range of high-voltageapplications includes several series ofmodular gas-insulated substations(GIS) for rated voltages of between 52 kV and 800 kV.

Over 2,000 stations with more than10,000 switch bays demonstrate theirvalue every day in 70 countries.Extensive experience in plant operati-on in a wide variety of conditions andwith many different requirementsforms the valuable basis of the needs-oriented development and productionof our gas-insulated substations, withtheir recognized high quality.

Characteristic advantages of the ELK-0 substations are

Space saving, compact design High availability Low maintenance and

repair requirements Short delivery and com-

missioning period Consistent modular

technology

General

An ingenious modular systemmakes possiblea variety of solutions

Gas-insulated switchgear (GIS) ELK-0is created by the combination of stan-dardized function modules such ascircuit breakers, disconnectors andearthing switches, instrument trans-formers, supplementary modules, etc.These 3-phase modules are connectedtogetherby meansofcarefully machinedflange connections.

The dimensions of these flanges arethe same with all modules, so thatvarious components can be combinedvery freely. This facilitates the designof a substation and its planning.

The individual modules are connectedin such a way that subsequentexpansion or the conversion of a sub-station can be carried out easily. Gas-tight barrier insulators ensure that anyeffect on adjacent substation compo-nents is kept to a minimum.

4

Bay with double busbar and cable connection Busbar with combined dis-

connector and earthing switch

Circuit breaker Current transformer Voltage transformer Line disconnector with

earthing switch

Make-safe earthing switch Cable sealing end Control cubicle

Set-up of a substation

5

The ingenious modular system offersthe planning and project engineer great flexibility for optimization. Hecan thus easily realize his concepts of the optimum configuration for thesubstations. Various criteria such asbasic circuit, routing of lines andcables, building size, accessibility, and provisions for extensions andrapid fault rectification are evaluatedindividually and taken into considera-tion accordingly.

During the project planning of substa-tions, all basic circuits used in classicsubstation construction can be realizedalso with our fully encapsulated GIS.Substations with single or multiplebusbars optionally with transfer bus-bar also can be created with standardmodules just as wellwith disconnectableor switchable busbars and bus cou-plings.

The function of the individual compo-nents, and thus also of the substations,is dependent on the increasingly strictsystem requirements for electrical net-works and their equipment, e.g. eco-nomy, safety, and quality. Here, anappropriate solution is GIS EXK-0:compact design, flexible application,extremely reliable primary and secon-dary technology.

Uniform, standard modules, which aretype-tested and manufactured in largenumbers, are joined to form individualsystems. Structures with great func-tional complexity are created by thecombination of clearly defined elements.This concept is a precondition foreffective, comprehensive quality assurance.

Busbar with combined discon-nector and earthing switch

The busbar is made by adjoining bus-bar components. The length of theseelements corresponds to the baywidth of 1200 mm.

Gas-tight barrier insulators in everyswitch bay avoid time consuming gasfilling and emptying of large gas com-partments. Telescopic transverseassembly elements facilitate tasksnecessary for on-site assembly andplant extensions or conversions.

The busbar phase conductors are fastenedbay by bay to gas-tight barrierinsulators. These insulators are eachcombined with a telescopic transverseassembly element,which facilitates thework necessary in event of station ex-tensions or conversions. Plug-in con-tacts inthe transverse assembly elementconnect the busbar conductors. Alter-nations in length caused by tempe-rature fluctuations are thereby flexibly compensated.

Mechanical strain on the insulatorsdue to differing heating of the indivi-dual conductors and the enclosuresare thus completely avoided.A combination of busbar disconnectorand maintenance earthing switch forsubsequent switchgear extension,maintenance, etc. is an integral partof each busbar module. The commonoperating mechanism for the

6

The system and its components

7

combined disconnector and earthingswitch is mounted at the front, andacts via bevel gears and an insulatingshaft on the three parallel contact pins.Depending on the direction of move-ment the contacts act as disconnec-tor or earthing switch (maintenanceearthing switch). By means of a crankhandle, manual operation of the com-bined disconnector and earthingswitch is also possible.

Two separate position indicators andauxiliary switches are positively con-nected to the operating mechanism.Furthermore, as the switching doesnot take place until immediately beforethe contact end positions are reached,an accurate overview of the contactposition is therefore always assured.

Busbar with combined disconnectorand earthing switch

Contact pin Disconnector contact Earthing switch contact Barrier insulator Transverse assembly

element

8

Circuit breaker with current transformer

The circuit breaker is equipped withtwo or three connection flanges. Theirposition and form is determined bythe station layout. As all other modu-les can be connected directly, bymeans of appropriate project planningvery compact and thus inexpensivestations can be formed.

The circuit breaker works as a single-pressure breaker according to theauto puffer principle with one breakper pole, and therefore requires verylittle maintenance.

The arcing chamber used in this breakerarises from the outdoor circuit breaker,which is tested under the most strin-gent conditions. It is characterized bythe consistent separation of the conti-nuous-current contacts and the auxili-ary contacts for the arc extinction.

Circuit breaker with integrated current transformer Arcing chamber Current transformer

Barrier insulator Hydraulic operating

mechanism

9

Auto puffer principle

Long-life auxiliary contacts for arcextinction and the absence of contacterosion at the continuous-current contacts make the need for inspec-tion and maintenance rare and inmost cases even superfluous.

The puffer piston connected to thecontact nozzle generates the SF6 gasflow necessary for arc extinctionduring the switch-off movement. Thegas suppresses the operating cur-rents and small short-circuit currents.Compression volume and contactgeometry are optimized with regard tolow-overvoltage, soft extinction beha-vior.

In the heat-up volume, the energypresent in the short-circuit arc is usedto heat the SF6 gas. The pressurethus created serves to extinguishshort-circuit currents up to the ratedbreaking current.

The compression power to interruptthe short-circuit currents is thus notperformed by the breaker operatingmechanism. The operating mecha-nism a spring-assisted hydraulicmechanism is used can therefore bemade especially simple and reliable.

The majority of the switching opera-tions are normal-load operations;most switching operations are thusperformed with the lower mechanicalload from the compression volume.Reaction forces and wear are accor-dingly low.

Breaker closed Interrupting operating

current

Interruptingshort-circuit current

Heat-up volume

Compression volume

Circuit breaker assembly

10

Hydraulic stored-energy spring mechanism

The hydraulic stored-energy springmechanism of the circuit breakerforms an ideal connection for thewear-free power transmission of thehydraulics system, with the robust-ness of a mechanical energy accumu-lator. A Belleville spring assembly ser-ves as an energy accumulator. Itsexcellent qualities include reliability,long-term stability and independenceof temperature.

The drive for three-pole switch actua-tion comprises four functional modu-les: recharging module with hydraulicpump and low-pressure tank, accu-mulator module with Belleville springassembly, working module with drivepiston and integrated end-positiondamping and a monitoring and con-trol module with open-close controlcoils. In the version for single-poleactuation, there are three working andcontrol modules respectively.

Tripping and enabling of the drive en-ergy is by means of tried and testedhydraulic drive technology components.In accordance with the accepted safetyphilosophy, the close-open changeovervalve is equipped with two redundantopen coils.

Hydraulic stored-energy spring mechanismBasic diagram Low pressure oil

High pressure oil Hydraulic pump Drive piston Changeover valve Storage spring

0 I

11

The drive has no pipe or screwconnections. The number of sealedpoints to the outside is kept to a mini-mum. Pressurized sliding gaskets arearranged so that unavoidable leakscan only reach the low-pressurechamber and never reach the outside.

The high- and low-pressure chambersare hermetically sealed, excluding thepossibility of long-term change to the hydraulic fluid caused by oxi-dization.

Hydraulic stored-energy spring mechanism for three-pole actuation

Hydraulic stored-energy spring mechanism for single-pole actuation

12

Cross unit with combined dis-connector and earthing switch

The line disconnector is located in across-shaped module. It is composedof the same active elements as thebusbar disconnector. Integral compo-nent of the disconnector is a motor-driven earthing switch.

In addition, this disconnector providesthe possibility of connecting a voltagetransformer. Here, the electricalconnection is made either before orafter the isolating distance, so thatthe voltage is either displayed for thestation side or the line side. Theconnecting flange for the voltagetransformer also serves as a test flan-ge for the high-voltage test of thesubstation or the cable.

In general this module is combinedwith a voltage transformer, a make-safe earthing switch, and a cable sea-ling end or a pipe outlet line.

Line disconnector with cable sealing end Contact pin

Disconnector contact Earthing switch contact Barrier insulator Support insulator Plug-in cable connection Voltage transformer connection Make-safe earthing switch

Factory-tested switch bays areassembled from functional units

13

Make-safeearthing switch

The make-safe earthing switch is fit-ted with a spring operating mecha-nism which makes contact switchingvery fast. It is therefore particularlysuitable as a line earthing switch, asany conceivable effects in the case ofincorrect switching are thus small.

The closed earthing switch can beisolated from the operational earthedenclosure during an inspection. Thereis therefore the possibility of creatingan electrical connection from outsidevia the housing of the earthing switchand the movable contact pins, whichare insulated from each other, to themain circuit. This considerably facilita-tes the adjustment and checking ofthe protective relays, cable checking,and locating cable faults. During op-eration, the insulation is short-circuited.

Make-safe earthing switch

14

Current and voltage transformer

For measurement and protection pur-poses inductive, single-phase currentand voltage transformers are used.For both transformers the primaryinsulation consists of SF6 gas. Thetransformers are particularly operation-ally safe, as this insulation material isnot subject to any aging. Feeder current transformers arearranged in the junction flange of thecircuit breaker. The available corevolume was determined to allowinstallation of up to four cores.

The current transformer is designedas a low-voltage transformer. Theavailable transformation ratios, secon-dary outputs, accuracy classes, etc.of the transformers correspond to theusual requirements of modern protec-tion and measurement technology.

The voltage transformer has a so-cal-led SF6 film insulation. Here, the indi-vidual layers of the winding are insula-ted from each other by means of plas-tic film and the intermediate spaceshave been impregnated in a specialprocess with SF6 gas.

On the secondary side of the voltagetransformers, two measurement win-dings and one open delta windingmay be provided for earth fault detec-tion.

Voltage transformer

Primary winding Secondary winding Transformer core Terminal box Barrier insulator

15

Cable sealing end

By means of the cable sealing end,cables of any kind can be connected.For the XLPE-insulated cables mostlyin use today, there is a cable sealingend with a short installation lengthand a completely dry solid insulation.

The main elements of the plug-in sea-ling ends are the plug-in socketsmade of epoxy resin and the cableconnectors with the pre-manufactu-red stress-cones made of siliconerubber. An advantage is the consist-ent separation of the substation andcable system installations.

For other types of cable, a sealingend is selected of which the maincomponent is the longer cable insula-tor for liquid-filled sealing ends.

16

SF6 outdoor bushing

The outdoor bushing allows the tran-sition from the enclosed substation tooverhead lines or the bare connectionof transformers.

Plastic compound bushings are prefe-rably used. They are characterized bya fiber-reinforced support pipe madeof epoxy resin with vulcanized shieldsmade of silicone rubber. These bush-ings are fracture- and explosion-proof, easy to handle and have excel-lent pollution layer characteristics onaccount of the hydrophobic insulationmaterial. Upon customer request, tra-ditional capacitor bushings can alsobe provided with porcelain insulation.

Supplementary modules

With regard to station layout variousconnection modules may be requiredfor combination of the equipment.These are primarily:

Pipe connections

Elbow pieces

T-pieces

The components are equipped with asupport or barrier insulator. Plug-inand tulip contacts serve for connec-ting the conducting paths.Occasionally, station sections arecombined with a transverse assemblyelement in order to facilitate subse-quent station modifications, exten-sions or repairs.

17

SF6 gas system

In accordance with the dual functionof the SF6 gas as arc extinction andinsulating medium we differentiatebetween the extinguishing gas com-partments, and the insulating gascompartments of the busbars, dis-connectors, instrument transformers,etc. The gas compartments aresegregated by gas barrier insulatorsand the gas pressure is monitored bytemperature compensated pressurerelays (density related relays).

All gas compartments have their ownautomatic vacuum coupling, so thatall maintenance jobs, like drawing agas sample or topping-up the SF6gas can be carried out without diffi-culty.

Control cubicle

The auxiliary electrical units requiredfor command input, warning, locking,etc. are accommodated in their ownindividual control cubicles.

The units are connected to the con-trol cubicles by means of controlcables with coded multiple connec-tors. These connections are alreadymanufactured and tested in the fac-tory. The electrical connections bet-ween control cubicle and controlroom are routed on terminal strips.

The door is fitted with the mimic dia-gram with the position indicators,associated control switches andvisual alarm indicators. By means ofkey-switches, the units' locks arereleased or switched to local or remo-te control.

As an alternative to the conventionalelectromechanical control system, amicroprocessor-controlled bay controland protection device REF542pluscan be used. It combines the basicfunctions control, protection, commu-nication and monitoring. Standardizeddigital interfaces permit easy connec-tion to the substation control system.

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Transportation, assembly, and maintenance

Factory-assembled and -tested substations

Thanks to the low weight of the ELK-0components, transportation andassembly of a substation is easy.Preferably, ELK-0 substations aresupplied in completely assembled andtested bays with the relevant controlcubicles.

Here, the following advantages maybe applicable: The assembly period at the installa-

tion site is very short and the work for substation commissioning is uncomplicated.

The insulating capacity has been proven in the factory by means of routine tests of the complete bays. As here a partial-discharge measure-ment was also carried out, impair-ment of the insulating capacity due to material or manufacturing faults can be safely ruled out.

On account of the small bay dimensions and weights, ELK-0 substations can also be delivered by air freight without problem. Complicated packaging and pre-servation are not required, so com-mercial use of the station can start earlier.

After the station has been set up, thegas compartments are filled with SF6gas. For this purpose, special servicetrolleys are available. As all gas com-partments are provided with valvecouplings which can be opened with-out gas or pressure loss, these opera-tions are very simple to perform. Gaslosses and emissions are thereforealmost completely eliminated. Afterthe switchgear has been checked forperfect mechanical operations, theresults of the commissioning tests arerecorded.

Factory-tested switchyard bays

19

On-site assembly of complete bays

High voltage test

20

Maintenance

The operational safety of fully encap-sulated SF6 insulated substations issubject to no external influence resul-ting from dirt, moisture or similar. TheGIS ELK-0 therefore requires extre-mely low-maintenance.

In the case of inspections, the insideof the switchgear is not interferedwith, so the substation can remain inoperation. The condition of the gasand hydraulic oil is checked and theactuators, auxiliary contact units,density monitors are subjected to afunction test.

Circuit-breakers and disconnectorsshould be inspected only after 5,000mechanical operating cycles. In addi-tion, repair of the circuit-breaker isscheduled after approx. 10-20 short-circuit cut-outs at the earliest, depen-ding on the switched-off short-circuitcurrent.

Experience shows that these limitvalues are far in excess of the re-quirements of practical operation.With respect to network planning, theusual precautionary measures andredundancies can therefore be consi-derably reduced.

21

22

Version examples

Gas insulated ELK-0 substations arealways the right choices when the lowspace requirements are an importantcriterion for the choice: for supplyingpower to cities and conurbations,industrial complexes, and whenaggressive environmental conditionsnecessitate a sheltered location.

All the usual station circuits can beoptimally implemented on account ofthe modular component system. Atthe same time, it is possible to takeinto consideration the various require-ments regarding building dimensions,subsequent station extensions, secu-rity of supply, comprehensive stationoverview, access to equipment, pro-tection concept, etc. on the basis of asolution tailored to the individual casein accordance with its value.

The following examples prove the fle-xibility of the system and are intendedto provide stimulus for the conceptionand planning of new substations.

The bay width is basically 1.2 m. Therequired building depth is generally 7 m, the building height less than 5 m.No crane is necessary for assemblingthe factory-assembled and -testedswitch bays and maintenance of theequipment; however, installation of acrane is recommended to facilitate thework and to save time.

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24

Double busbar

This circuit is the most common cir-cuit version for important key-pointsubstations, power plant supply, etc.

If both busbars are operated withequal priority instead of the opera-ting method with main and reservebusbars the principle of busbarseparation can be applied to reducethe short-circuit current. The two bus-bars and their feeders belong toseparate sub-networks. If required,individual feeders can be allocated tothe other sub-network. This concept relieves the stations as a

result of low short-circuit loading, lon-ger maintenance intervals and offersgreater supply security.

The possible coupling versions areparticularly varied: The simple buscoupling or the combined bus sectio-nalization and coupling with six oreight disconnectors are two exam-ples. Double disconnectors evenallow subsequent high-voltage testsafter station extensions or mainte-nance measures during partially nor-mal operation.

E07 E06 E05 E04 E03 E02 E01

25

Feeder E01, E03, E05-E07

4900

7000

2500

500

2350

3600

Feeder E02

E07 E06 E05 E04 E03 E02 E01

1200

14000

APPR.10000

7000

26

Single busbar

Smaller stations or single- or double-feed stations are frequently designedwith single busbars. Here, in the inte-rest of adaptable system manage-ment, bus section couplings and buscouplings are provided. This means,for example, that part of the stationcan remain in operation during stati-on extension work.

The layout of a station with simplebusbar is similar to that of doublebusbar stations, as only the lower orupper busbar is eliminated. If theappropriate connection flanges arealready provided on the circuit-brea-kers on the initial version, it is easysubsequently to upgrade to a doublebusbar.

Feeder E01-E03

500

7000

4500

2500

2950 36

00

7000

1200

FUTURE E01 E02 E03 E04 E05 E06 E07 FUTURE

16000

27

E01 E02 E03 E04 E05 E06 E07

VIEW X

FUTURE E01 E02 E03 E04 E05 E06 E07 FUTURE

28

H-circuit

The H-circuit is frequently used tosupply industrial companies or smallerregions. Two feed lines and two step-down transformers are optimal withregard to supply reliability and networkreserves. The station can be operatedas a double-feed station, with closedcross connection also as a ring sub-station.

If a subsequent station extension isunder consideration, the simple bus-bar with section coupling is selectedas basic layout. There is even subse-quently the possibility of convertingthis to a station with double busbarand bus coupling.

If subsequent possibilities for extensi-on are not required, the especiallycompact version without busbar isselected.

Section A-A

E01(E03)

E02(E04)1

7500

20000

E04E02

E01 E03

29

E01 E03

E02 E04

30

11/2 - breaker method

The 11/2 -breaker method is a traditio-nal circuit with which the non-availabi-lity of the circuit-breaker during main-tenance is taken into particular consi-deration. It is used primarily withmaintenance-intensive breakers, andwhere the secondary medium-voltagenetwork does not take even a briefadditional load, and a primary trans-mission network is not provided.

Such networks or stations are usuallyoperated in such a way that all swit-ches are closed. Each feeder is thenfed from two sides, so that even afaulty busbar can be switched offwithout reducing the supply.

EXCEPT E02

EXCEPT E14

EXCEPT E11

2500

31

EXCEPT E056050

9500

500

3600

9500

E01 E02 E03 E04 E05 E06 E07 E08 E09 E10 E11 E12 E13 E14 E15

F01 F02 F03 F04 F05 F06 F07 F08 F09 F10 F11 F12 F13 F14 F15

32

Mesh substation

Similarly to the 11/2-breaker method,the ring bus allows uninterrupted ope-ration of all cable and line feederseven in the event of switchgear main-tenance work. With this circuit, thenumber of breakers and the cableand line feeders is equal, so the sta-tion is in general more inexpensivethan a corresponding version with 11/2breakers per bay.

EDER E01

7500

3500

2500

33

Preferentially small substations withfor instance four bays are built-upwith this layout. Switching of one fee-der implies at least short-time inter-rupting the ring-busbar. This is inap-propriate for big substations, becausein the case of a short-circuit failurethe unplanned opening of the ringbusbar causes considerable load-flowvariations or supply interruptions.

FEDER E02

E01 E02 E03 E04

9500

7500

VIEW X

E01 E02 E03 E04

34

Technical data

Rated values*

Operating voltage kV 72.5 123 (126) 145 170

Operating frequency Hz 50 / 60

Lightning impulse withstand voltage to ground kV 325 550 650 750

Lightning impulse w. voltage over isolating distance kV 375 630 750 860

Power frequency withstand voltage to ground kV 140 230 275 325

Power frequency w. voltage over isolating distance kV 160 265 315 375

Operating current A 1250 4000

Peak withstand current kA 80 164

Short time withstand current kA 31.5 63

Breaking current kA 31.5 63

Making current kA 80 164

Min. insulating gas pressure at 20 C kPa 520

Min. quenching gas pressure at 20 C kPa 600

*Higher data on request

35

Pub

licat

ion

No.

1H

DX5

8009

4 E

N r

ev. a

P

rinte

d in

Ger

man

y 03

.05

2000

ABB AGHigh Voltage ProductsBrown-Boveri-Strasse 3063457 Hanau-GrossauheimGERMANYPhone: + 49 6181 509-660Telefax: + 49 6181 509-661E-Mail: powertech@de.abb.comInternet: http://www.abb.com/highvoltage

Note:We reserve the right to make technical changes or modify the contents ofthis document without prior notice. With regard to purchase orders, theagreed particulars shall prevail.ABB does not accept any responsibility whatsoever for potential errors orpossible lack of information in this document.

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