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Transmission & Distribution

sustainable solutions for a better life.

www.vatech-td.com

TH7mSF6 GasInsulated Switchgearup to 145kV

handbook 5 482 696 En B

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Presentation 2

Main characteristics 3

Switchgear 4

Instrument transformers 10

Connections 12

Primary components 14

Installation and maintenance 17

Circuit breaker-disconnector 4

High-speed earthing switch 9

Current transformer 10

Voltage transformer 10

Cable connections 12

Enclosures 14

Insulators 15

Conductors 15Density switches 16

Safety membranes 16

Packing and shipping 17

On site storage 18

Erection 18

Site tests 18

Maintenance 19

Combined disconnector-earthing switch 7

8

12

13

11

20

Electrical control of the combined disconnector-earthing switch

Overhead connections

Direct connections on power transformers

Surge arresters

Examples of installation

Table of contents

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TheTH7m indoor GIS(Gas Insulated Switchgear)

is of three-phase design for voltages of up to

145 kV and short-circuit currents up to 40 kA.Hexabloc TH7m can be used for all standard

substationconfigurations.

The design of the TH7m has been simplified byusing the circuit breaker-disconnector for both theprotection and disconnection of the outgoingcircuits and a combined device for the isolationandearthing of thebay.The resulting reduction in the number of devicessimplifies operation of the substation, improvesreliability, reduces overall size and makesinstallationeasier.

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Presentation

sepam

2000

sepam

2000

sepam

2000

GHIJ

Q01

Q10

Q9 0

Q01

Q10

Q90

Q50

Q51

Q80

SF6

selec f aul t

local

maint.

r emot e

Busbar1

Q50

Q51

sepam

2000

6

4

5

1

2

3 7

Example of a typical outgoing bay

The combined disconnector-earthing switch

forms an integral part of the busbars. It is used to

connectthe busbars to thebay orto earth thebay.

The circuit breaker-disconnector is used toprotect and isolate the outgoing lines, eliminatingtheneedfor a linedisconnector.The outgoing bay is typically connected using adry cable with synthetic insulation and equippedwithplug-in terminations.The outgoing line is equipped with a high-speedearthingswitch.

The improved reliability procured by thereduction in the number of devices makes itpossible to reduce the number of SF6

compartments.The typical outgoing bay includes the followingcompartments:- the compartment for the busbars and thecombined disconnector- earthing switch- the compartment for the circuit breaker, currenttransformer, cable terminations and high-speedearthing switch.- the voltage transformer which remains isolatedfrom the common compartment.

1

23

- Busbars and c

- Circuit breaker-disconnector-

ombined disconnector-earthing switches

Current transformer

4

5

6

7

- High-speed e

-

- Voltage transformer

- Local control cubicle

arthing switch

Cable box

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3

Ratings

Maximum rated voltage...... .................................. ................................... ........................up to 145 kV

Maximum rated lightning withstand voltage ....................................................................up to 650 kV

Maximum rated lightning withstand voltage between disconnectorand circuit breaker-disconnector contacts.......................................................................up to 750 kV

Rated withstand voltage at power frequency ..................................................................up to 275 kV

Rated withstand voltage at power frequency between disconnectorand circuit breaker-disconnector contacts.......................................................................up to 315 kV

Rated frequency.............................................................................................................50 and 60 Hz

.................................. .................................up to 3150 A

................................. .................................up to 3150 A

Rated peak withstand current ................. .................................. .............................up to 108 kApeak

............................... .................................. ....................up to 40 kA x 3 s

Rated filling pressure .............................. ................................... .................................. ........0,63 MPa

Alarm pressure........... .................................. ................................... .................................. ...0,60 MPa

Minimum operating pressure ...............................................................................................0,58 MPa

Circuit breaker :

- rated breaking capacity............................................................................................................40 kA

- rated making capacity ............................... .................................. ..................................108 kA peak

- rated operating sequences ................................. ................................... .....................OCO - 1' - CO

CO - 15'' - CO

Rated making capacity of earthing switchwith short-circuit making capacity............................. ................................... ...........up to 108 kApeak

Rated current for continuous duty on feeder

Rated current for continuous duty on busbar

Short-time withstand current

Main characteristics

Reference standards

The specific requirement of GIS are given in IEC 60 517, gas insulated metal enclosed switchgear forrated voltage of 72.5kV andabove. ForindividualGIScomponents additional IECstandardsapply:

CEI 60044 Instrumenttransformers.

CEI62 271-100

CEI 60071 Insulationcoordination.

CEI 60 129 Alternating currentdisconnectors and earthingswitches.

CEI 60270 Partial discharge measurements.

CEI 60 376 Specificationandacceptance ofnewsulphur hexafluoride.

CEI 60 480 Guideto checkingofsulphurhexafluoride (SF6)taken fromelectrical equipment.

CEI 60 694 Commonspecificationsforhigh-voltage switchgearand controlgear.

CEI 60 815 Guidefor the selection of insulators in respect ofpollutedconditions.

CEI60 859 Cable connection for gas-insulated metal-enclosed switchgear for rated voltage of72.5 kVand above.

CEI 61 128 Bus-transfercurrentswitchingby disconnectors

CEI 61 129 Alternating currentearthing switches- Induced currentswitching.

CEI 61 634 High-voltageswitchgear andcontrol - Use andhandlingfo sulphurhexafluoride (SF6)in high-voltageswitchgearand controlgear.

CEI 60 517 Gas-insulatedmetal enclosed switchgear forrated voltageof 72.5kVand above.

CEI 61 259 Requirements forswitching ofbus-chargingcurrents bydisconnectors.

Alternating current circuit-breakers

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Switchgear

Circuit breaker

-disconnector

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The circuit breaker-disconnector protects andisolates the circuits.The circuit breaker-disconnector combines thebreaking characteristics specific to circuit

breakers with the isolation and circuit-separationcharacteristicsspecific to disconnectors.

The mechanism of the position indicator complieswith therequirementsof IECstandard 60129.

The isolation characteristics have been checkedafter complete simulation of the circuit-breakerservice life, which is themost restrictive case.

The breaking chamber is of puffer and self-blasttype.The circuit breaker is driven by mechanicaloperating drive. The energy required to operate

the circuit breaker is stored in helical compressionsprings.

1

2

3

4

5

6

78

9

10

- Safety disk

- Drive mechanism

- Filling coupler

- Density switch

- Push button

- Mechanical operating mechanism GMv

- Local control cubicle- Insulator support

- Breaking chamber

- Barrier insulator

7

9 10

64 5321

8

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The breaking chamber is self-blowing and self-expansive. According to the IEC 62 271-100standard, the circuit breaker is restrike free.

To disrupt high currents, energy of the electric arc

is used to increase pressure in an expansion

chamber. When current cancels out, the

pressurized gas, led by the nozzle, is blown on

the arc to disrupt it. Lower intensity currents are

blown thanks to the compression of a swabbingvolume, which throws SF6 on electric arc

In the interrupting unit, permanent current flow is

separated from the transient current flow.

The contact parts subject to arcing are made of

refractory materials.

An insulating sleeve prevents decomposition

product from accumulating on the insulator

support.

.

Breaking chamber operating principle

5

Fig.1

Fig.2

Fig.3

Fig. 4

Circuit breaker closed,

allowing continuous flow of

current via the main contacts.

Start of opening. Main

contacts disengage. The diagram

shows the disengaged position of

arc contacts. The gas passes

from V2 to V1. The swabbing

valve is open.

Opening continues. Arccontacts disengage to create an

electric arc between these two

contacts. In case of high-intensity

current, high pressure closes the

valve between V1 and V2 to limit

pressure on V2 piston. Pressure

on V2 is regulated, which allows

for energy savings over control.

Current is stopped. In this

position, there is blowing in the

nozzle. Gases leave the hot spot.

Fig. 1 Fig. 2 Fig. 3 Fig. 4

: expansionchamber

: swabbing volume

V1

V2

1

2

3

4

5

6

7

8

9

10

- Fixed contact

- Fixed arcing contact

- Insulating nozzle

- Moving arcing contact

-

- Moving contact

-

-

-

- Support insulator

Expansion chamber

Swabbing valve

Swabbing volume

Regulation valve

10

9

87

6

5

4

3

2

1

2

1

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6

1

3

4

5

10

1112

13

2

89

7

6

1

2

34

5

6

7

- M

- C

- P- C

- C

- C

- O

otors and spring charging mechanism

losing springs

rimary transmissionlosing cam

losing lock

losing crank

pening lock

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The DTH7m circuit breaker is driven by the GMvoperating mechanism.

The GMv operating mechanism is simple, robustand particularly reliable. It is used for theconventional circuit breakersof the145kVrange.The operating mechanism uses only tried andtested techniques that are perfectly controlled.Reliability has beenfurther enhanced by reducingthenumberof components.

The drive springs are of the helical compressiontype. The primary transmission mechanism is of

the chain type. The latching part are speciallydesigned to operate without lubrication orgreasing. As a result, the operating mechanism isvirtually maintenance free.The GMv operating mechanism allows to achievean O-CO cycle withoutreloadingsprings.

GMv operating mechanism

8

9

10

11

12

13

- C

- O

- O

- O

- P (open/closed)

- C

losing coil

pening coil

pening springs

perating crank

osition indicator

harged/discharged status indicator

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The combined disconnector-earthingswitch fulfils

the functions of a disconnector and of an earthing

switch.

The combined selector switch disconnector isdesigned to operate in charge, that is to transfer

charge currents from a busbar to another. Thus, it

has a breaking and making capabil i ty.

Furthermore, the moving contact stops in

intermediate position. This third position

guarantees insulation distances for an open

disconnector and an open earthing (across gap

contacts and phase-earth). This stop in

intermediary position is not necessary on the

busbarand for linedisconnectors.

The combined disconnector-earthing switch uses

a blade-type contact.The movement of the blade-type contact makesthe connection to the busbar or earths the circuitbreakerupstreamcircuit.

The disconnector is fitted with an electrical

operating mechanism and a manual operating

mechanism.The position of the contacts may be checkedthrough the viewport. A portable endoscope maybe used to facilitatechecking.The same type of gear motor is used to drive thecombined disconnector-earthing switch and thehigh-speed earthingswitch.

Combined

disconnector-

earthing switch

7

1

8

-

- Flange

B

- M

- F

- B

- M

- F

- B

2

3

4

5

6

7

usbar

oving contact screen

ixed earthing contact

arrier insulator

oving contact blade

ixed disconnector contact

usbar

- Expansion joint

- Cutene chip (only for selector

switch disconnector)

9

10

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Two combined disconnector-earthing switchesadjacent busbar

2 10 5

8

9

1

23

4

7

5

6

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8

Electrical

control of the

combined

disconnector-

earthing switch

Electrical controls are based on the screw/nut

principle, a well-known and reliable system that

allows to transmit reliabledrive.

Because first nut goes until end of stroke, the

stabil i ty of the intermediate posi t ion is

guaranteed. The parts of the screw/nut

mechanism are specially treated to operate

without lubrication or greasing. The controls thus

operatewithoutanymaintenance.

All control components are integrated in an IP41

case.

Manualcontrolusinga handle isalsopossible.

This principle guarantees precise and reliable

kinetics. The control is activated by gear motors

monitored using limitswitches.

Closed disconnector

Schematic diagram

Open disconnectorOpen earthing switch

Closed earthing switch

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1

2

3

4

5

- Earthing drive

- Disconnector drive

- Push button to control electric lock

of access trap

- Key selector switch

- Access trap to handle

1 2

3 34

5

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9

The earthing switch uses a contact pin and tulip

contact mechanism.

The earthing terminals can be isolated from thesubstation by simply removing a shunt.

The mechanism of the position indicator on the

earthing switch complies with the requirements

of IEC standard 60129.

It can close in case of

short-circuit.

High-speed

earthing switch

1

2

3

4

5

6

- Fixed contact

- Moving contact

- Drive crank

- Drive shaft

- Isolatable earthing terminals

- Fast closing mechanism

( )protection cover removed

6

25 1

3

4

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14

The enclosures are made of cast or welded

aluminium alloy.

Enclosure design complies with European

pressure vessel codes(CENELEC).

Standard colour of enclosure external painting:

RAL7035.

Thanks to their modular design a small number

of enclosures are readily adaptable to most

substation layouts:

busbar disconnector enclosure,- circuit breaker enclosure,

- current transformer enclosures,

- voltage transformer enclosure,

- cable termination enclosure.

-

Primary components

Enclosures

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Circuit breaker-disconnector enclosure

Current transformer enclosures

Voltage transformer enclosure

Cable termination enclosure

Busbar disconnector enclosure

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15

1

2

3

- Insulator conductor insert

- Sliding contact ring

- Silver-coated copper nozzle

4 - Aluminium tube

Insulators

1

2

3

3

2

1

1 2 3 4

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Barrier insulator

The barrierinsulatorsare made up ofa metal plate

supporting threesingle-pole insulators.

The single-pole insulators are made of epoxyresin moulded around the central conductor

Support insulator

1

2

3

- Conductor

- Insulator

- Fixing device

1

2

3

- Support

- Single-pole insulator

- Conductor insert

The conductors are made of aluminium alloy. The elastic contact parts are made of copper or

silver-coated copper.

Conductors

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17

Installation and maintenance

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The TH7m is shipped as complete bays andTransportUnits(TU).Each bay is fully factory-assembled. Theswitching and monitoring devices are fully

connected to thecontrolcubicle.The voltage transformers and the busbarcomponents are generally shipped in separateTransport Units and not with the fully-assembledbays.To prevent the ingress of dust and moisture in thegas compartments, all transport units that can besealed are pressurised with dry SF6 gas ornitrogenat a pressureof 0.03 MPa.

The TUs are placed in a rigidly framed plywoodcase suited foroverseas transport andhandling.The dimensions of the TUs have been optimisedtaking into account the most frequently

encountered transport limitations and handlingfacilities.The complete bays can easily be moved using abalancedlifting beam.The maximum net load ofa bayis 3000 kg.

Packing and

shipping

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18

Electrical power supply to the site:

Preparation erection:

Erection of fully assembled units:

Electrical power supply should be made available

dur ing the enti re mount ing per iod. Thespecifications for the electrical power supply on

the site will be stipulated by common agreement.

The electrical power supply should be able to

meet the requirements of the gas processing

plant, the vacuum cleaner, hand tools and lifting

equipment.

The order in which the HV bays are mounted is

determined by mutual agreement between the

customer and the manufacturer. The order

depends on the environment of the GIS, ease of

accessand liftingmeans.

The GIS consists exclusively of complete units

and a small number of separate switchgear

devices or busbars. Installation of the units

required a minimum amount of site work. Only

compartments that are opened on site require full

SF6gasprocessing.

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Transport unit packaging is designed to prevent

any damage to the equipment during transport

and the storage period of 6 months from ex work

shipment to beginning of erectionon site.

The transport units must be stored on site in a

ventilated building, free from dirt and dust and not

subject to flooding.

If the planned storage exceeds 6 months or if theconditions are particularly severe it is necessary

to install periodic inspection and maintenance

worksduring thestorageperiod.

On-site storage

Instal lat ion and pre-commiss ioning are

performed under the technical responsibilityof the

manufacturer.

The manufacturer either carries out erection or

supervisesby the user'sinstallationpersonnel.

Erection

Erection area conditions

Site security:

GIS mounting requires a clean and dust free

environment.Civil works should be finished before mounting

starts.

The floor should have a firm surface and be easy

to keep free from dust. The floor should be clean

and unencumbered by tools or equipment not

requiredfor mounting theGIS.

Walls and ceiling should be of such quality that

they do not peel. If necessary, a coat of suitable

"anti-dust" paint should be applied on all these

surfaces.

Suitable crane, lifting devices and scaffolding

should be provided. Adequate interior lighting

shouldbe providedduringtheerection period.

Access to the site should be restricted to those

people required formounting the GIS. Hand tools,

special tools and certain spare parts should be

storedin lockedpremises under supervision.

After completion of erection, the following testsare performed:

- checks and verifications of the protection relay

settings,

- checks and verifications of the interlocks

betweenbays,

- checksand verificationsof switchingdevices,

- checks and verifications of the gas supervision

system,

- high-voltage dielectric tests.

Tests are carried out after mounting on site inorder to detect possible damage incurred during

transportation, storage or finalassembly.

Tests are performed under the technical

responsibilityof the manufacturer.

As switchgear erection proceeds, the following

testsare performed:

- measurement of the resistance of the main

circuit,

- tightness tests of each compartment sealed on

site.

Site tests

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H configuration using a bus section circuit breaker

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3650

4840

600

1000

494

0

1800

1500

2900

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