Produkte Schaltanlagen Visaxa067 e

8/14/2019 Produkte Schaltanlagen Visaxa067 e

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T&DPower Distribution

VISAX

MV Metal-clad Switchgear


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VISAX: A New Generation of Medium Voltage Switchgear

Fig. 2 - Lateral cross-section of

conventional switchgear.

1

2

3 4

5

6

Fig. 3 - Lateral cross-section

of VISAX switchgear.

Fig. 1 - Direct power line.

VISAX combines the advantages of

the most advanced withdrawableswitchgear and the benefitsassociated with simplifiedarchitecture: reliability, functionalsafety, security.

Original architecture

The circuit breaker engages directlywith the busbar, the number ofconnections and isolating elementsis significantly reduced.

Simple architectureThe innovative design of VISAX isbased on new metal-cladswitchgear architecture (fig.1)where all the functional elementsare mounted in a direct linebetween the busbar and the cableterminals.

Low voltage compartment

Busbar compartment

Circuit breaker compartment

Cable compartment

Compartment for the extraction of hot gases

1 - Busbar secured to the connection spouts2 - BLV self-isolating circuit breaker

3 - Multipurpose bushing

4 - Current transformers

5 - Cable terminals

6 - Earthing switch


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Fig. 4 - Longitudinal circuit breaker.

The originality of VISAX :

an isolating circuit breakerThe circuit breaker is incorporatedin a rotary isolator, thus forming adual-purpose module : circuitbreaker and isolator.

This technical innovation has beenmade possible by the use of avacuum circuit breaker, the poles ofwhich are arranged longitudinally(the three poles of the operating

mechanism are aligned along asingle axis).

VISAX switchgear conceptInnovation through rotationThe isolation function between thebusbar and the cables is providedby 90 rotation of theisolator/circuit breaker (Fig. 5).

Disconnection is thus performed by

rotation of the circuit breaker.

Fig. 5 - Disconnection by rotation.

Description of the 3 positions

In the "service" position (Fig. 6a),the poles of the circuit breakerare in the vertical position. Oncethe circuit breaker has beenopened, the poles can rotate toreach the "disconnected"position. They therefore withdrawfrom the connection spouts toadopt a horizontal position(isolated position).During this rotation, a metal

shutter is automatically drawnacross and obstructs access to thebusbar.

Fig. 6a - Service position: circuit breaker

engaged (opening/closure).

Fig. 6c - Removed position (the handling

trolley is not shown ) : testing and checking

operations may be performed on the circuit

breaker.

The withdrawal of the circuitbreaker (Fig. 6c) is then possibleafter insertion of an isolating

screen between the multipurposebushing and the circuit breaker.

Fig. 6b - Disconnected position or Test :

circuit breaker disengaged through rotation

(isolated position).

In the "disconnected" position

(Fig. 6b), the front face of thecubicle may be opened incomplete safety. Tests and checksmay then be carried out.


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VISAX: user safety

The circuit breaker compartment after

withdrawal : no access to live sections.

(1)

VISAX metal-clad switchgearIn order to guarantee the safety ofthe operator during checkingoperations, the circuit breakercompartment on VISAX switchgearis fitted with an earthed metalshutter (1). When the circuit breakerrotates, this shutter is automaticallydrawn across to separate thebusbar and circuit breakercompartments.

When the circuit breaker is in theisolated position, access to theconnection spouts and the cableterminals is therefore protected: thedoor may be opened in completesafety.

Prior to withdrawal of the circuitbreaker, an isolating screen (2)must be inserted so as to prohibit

access to the multipurpose bushingsand thus provide the user with fullprotection.

(2)

Enhanced interlocks

and safety devicesApart from the conventionalinterlocks, a particularly reliablechain of interlocks has beendeveloped. These mechanicalinterlocks are simple, robust andare located, for the most part, onthe front of the unit.

For total reliability, the pre-assembled interlock plate has been

designed as an independent sub-assembly, requiring no adjustmentduring integration into the unit. Thereliability of the interlocks is thusenhanced for the greater safety ofthe personnel.

The optional motorisation ofisolation and earthing operations isfully integrated into the interlockingdevices. Therefore, in the event of

the loss of the auxiliary powersupply, the manual operations canbe performed without risk to theoperator, as the mechanicalinterlocks then take priority.

Safety in use

The original architecture of VISAX,combined with the presence of agas extraction duct, make itpossible to install the unit flush tothe wall.

In this way, all the steps involved inswitchgear operation are performedfrom the front of the unit forcomplete user safety.

A unit which allows true wall mounting.

... and space savingThe fact that the unit can be

mounted against a wall allowsspace saving in substations,making it possible to overcomecertain dimensional restrictions.


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A single duct for the extraction of hot

gases.

Internal arc withstand

The rigid construction of the VISAXunit, incorporating exhaust flaps oneach compartment, ensures perfectinternal arc withstand.

Designed and tested according tothe latest standard, CEI 298Appendix AA, each compartmenthas an internal arc withstand whichconforms to criteria 1 to 6.

Enhanced personnel safety isoffered as manual operations areaffected with the doors closed.

The gases are channelled ina special compartmentAn advantage specific to VISAXarchitecture is to allow, thanks to asingle duct located at the rear of theunit, the collection and the

evacuation of the hot gases in theevent of internal arcing.

This duct, a standard component inVISAX units, is designed to collectthe gases from independent flaps,specific to each of the3 compartments: cables, circuitbreaker and busbar.

Should a problem arise in one of

the compartments, it does not affectthe others in any way.

Operator safetyIn this way, the hot gases areextracted at the back of the unit,towards the top, as far as possiblefrom the operator, for improvedsafety.

The safety conditions withinsubstations are thus enhanced. Thehot gases coming from these ductscan easily be collected from each

unit by a conduit (optional) andexpelled outside the substation.


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Reliability of information and ease of operation

Operation from the front panel.

safety from the front face of the unit

by direct action on the operatingmechanism.

Actions on the circuit breaker(opening/closing) while it is at theservice position are performeddirectly via the push buttons locatedon the front door of the unit,whereas isolation of the circuitbreaker is performed by insertingthe isolating crank handle through

the door.

Operation from the front

panelThe original architecture of VISAXprovides the user with a newdimension in reliability and safety,both in terms of operation andreadings.

VISAX architecture allows allactions associated with the circuitbreaker/isolator and the earthingswitch to be carried out in complete

Status and positions clearly visible, without

intermediate or interface systems.

The position of the earthing switch is clearly

visible to the operator.

Certainty of positional

informationThe front-to-back layout of all theelements in the main circuit enablesthe operator to see directly the axesof both the circuit breaker and theearthing switch.

The operator is left in no doubt, ofthe "service" or "disconnected"

positions therefore benefiting frominherent reliability.


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Self evident operation andindicationThe information essential tooperation of the switchgear is laidout ergonomically and grouped onthe front face, in areas clearlyidentified by specific bluecolouring. The operator thus hasaccess to the main information bysimply reading:

from the legend plate located on

the door of the circuitbreaker compartment (fig. 1),

from the band located on theright hand side of the cablecompartment (fig. 2).

The circuit breaker mimicdiagramThe single line drawing of the unitand the positions of the circuit

breaker are indicated by the mimicdiagram. The mimic diagramallows the operator to view, without

the slightest ambiguity, the status ofthe circuit breaker: open, closed,isolated, in operation.

Furthermore, the circuit breakerrating plate, the operation counterand the status of the spring of theoperating mechanism are clearlyvisible from outside the unit, withthe door closed.

The earthing switch mimic

diagramThe information on its statuscorrespond to reality without theslightest risk of error, as theposition indicator forms an integralpart of the axis of the earthingswitch.

Mimic diagrams reflectingreality in all circumstancesThe mimic diagram (fig. 3) of the

single line drawing on the frontface of the unit incorporates theposition indicators directly. This

Fig. 1 - Status of the circuit breaker.

mimic diagram is entirely made upof mechanical elements whichremain operational even in theevent of loss of power supply to theswitchboard.

The isolation distances and the

position indicators are totallyreliable and are clearly visible fromthe front face of the unit.

Fig. 2 - Status of the earthing switch.

Fig. 3 - Circuit breaker status: clear, distinct information.

Service position

circuit breaker closed circuit breaker open

Disconnected and Test position

circuit breaker open circuit breaker closed


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A solution suited to your applications

VISAX : created for a modern

world of communicationThe environment is changing and isleading to an evolution in needs,particularly in the fields ofcommunication and remote control.

The basic design of VISAX units

Rated voltage (kV) 7.2/12 17.5 24Rated withstand voltage

50/60 Hz - 1 min (kV rms) 28 38 50Lightning impulse (kVp) 75 95 125

Rated currentCubicle (A) 2500 2500 2500Busbar (A) 2500 2500 2500

Short time currentRms. value (kA 3s) 16/25/31.5/40* 16/25/31.5 16/25Peak value (kAp) 40/63/80/125* 40/63/80 40/63

Breaking capacity (kA) 16/25/31,5/40 16/25/31,5 16/25

Internal arc withstand (kA 1s) 25 25 25(kA 0.15s) 40

Degree of protection of the enclosures IP 3X(1) IP 3X(1) IP 3X(1)

Height with low voltage compartment (mm) 2150/2350 2150/2350 2450/2650Height of low voltage compartment (mm) 625/825 625/825 750/950

Width (mm) 1250 A 650(3)/800(2) 650(3)/800(2) 800/1000(2)

1600 A 800 800 10002000 A 900 900 10002500 A (4) 900 900 1100

Depth (mm) 16-25 kA 1260 1420 155031.5 kA 1460 1420

40 kA 1460Approximate weight of a cubicle 500 550 600excluding voltage transformer (kg)

Main characteristics

* Excepted earthing switch 1sec - 100 kAp - (1) for any other degree of protection, please contact us - (2) equipped with withdrawable voltage transformers

(3) short time current 25 kA - (4) forced ventilation for 2500A - Please contact us.

incorporates the features of remotecontrol and remote signalling.

Motorisation : an easysolutionThe motorisation of the circuitbreaker/isolator and earthingswitch was taken into account from

the very start of the developmentprocess.

On the motorised version,operations can be performedmanually if required, and themechanical interlocks take priorityin all circumstances.


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Incoming (or outgoing) unit fitted with withdrawable Voltage Transformers (VT) and surge arrester

(fixed VT also available).

Load break switch - fuse unit (ISR type load break switch).

Metering/measurement unit with fixed VT and busbar earthing.

Coupling - bus riser unit with withdrawable VT.

VISAX : a complete range


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The essential components of the VISAX concept

Hot gases extraction duct (standard)

A duct collecting the gases from the ducts of a

series of units is proposed as an option.

Compartment for inter-unit low voltagecableway, with customer terminal block

accessible.

Busbar compartment

Optional: the compartment may be partitioned

between units and the busbars isolated.

Cable compartment

From 1 to 4 single core cable per phase

(according to power handled) may be connected

to the multipurpose bushings.Three-core cables

may also be connected.

Voltage transformer. (3)

The multipurpose bushing performsthe following functions: location of ring type current

transformers,

power connection between circuitbreaker and cable compartments,

section for the connection ofmedium voltage cables,

capacitor divider for signallingthe presence of voltage on thecables.

Incoming/outgoing andcoupling/bus riser units may befitted with voltage transformers, withor without fuses.

They are available in two formats,fixed, easy to dismantle, orwithdrawable, which can beextracted from the front face of theunit.

VISAX is fitted with an earthing

switch with making capacity onshort circuit current.

Earthing switch. (2)

Multipurpose bushing. (1)

(1)

(3) (2)


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BLV type self-isolating rotative vacuum

circuit breaker

(A)

(B)

(C)

(D)

Fig. 2 - Pole.

Fig. 3 - Vacuum interrupter.

Fig. 1 - Operating mechanism.

The isolating circuit breaker

The BLV circuit breaker constitutesthe key element in VISAX units.

During isolation, the assemblycomprising the poles and theoperating mechanism rotates. Thecircuit breaker is a self-supportingmodule which only exerts minimalforces on the mounting points.Consequently, the variousoperations only require low energy

and the long-term reliability isfurther enhanced.

The elements making up theBLV circuit breakerThe circuit breaker is fitted with aspring-loaded mechanicaloperating mechanism (fig. 1)specially developed and optimisedfor the specific characteristics of thevacuum interrupters. Its designbased on a single shaft and spiralspring for both opening andclosing operations guaranteesexceptional reliability and safety.

The vacuum interrupters are locatedin single-pole enclosures (fig. 2).These enclosures, made of syntheticresin, provide not only the requiredlevel of insulation, but also thecomplete protection of theinterrupters from external damage.

The vacuum interrupters (fig. 3) usethe most advanced technology to

control the arc: the axial magneticfield. They are essentially made upof a sealed ceramic enclosurecontaining the highly pure coppercontacts. One of these contacts isfixed (A), the other moving (B) bymeans of a metal bellows (C). Ascreen (D), located around thecontact zone, collects the metalvapours created by the arc.


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ALSTOM Transmission & Distribution - Appareillage moyenne tension - Boulevard de la Rsistance - B.P. 4019 - 71040 Mcon Cdex 9

A067-

AMT-

12/2000-

-ALSTOM-

2000.

ALSTOM2

000-

ThelogoA

LSTOMa

nd

theirframeworksaretrademarksandservicetrademarkapplicationsofALSTOM.

Theothernamesmentioned,registeredornot,arethepropertyoftheirrespectivecompanies-

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