130405-buj vakuum generatorschalter en

8/9/2019 130405-BuJ Vakuum Generatorschalter En

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Answers for infrastructure.

Vacuum Circuit-Breakers for

Generator Switching Applications

siemens.com/generator-breaker


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Grow with your requirements

No question: The worldwide energy

demand will continue to increase rapidly,

placing higher performance requirements

on energy suppliers and industrial

facilities.

To provide them with the decisive advan-

tage, Siemens has been constantly devel-

oping and improving high-current and

generator circuit-breakers, which are able

to withstand increasingly higher currents.

The top priorities are reliability and main-tenance-free design throughout the entire

service life. With comprehensive simula-

tions, preliminary studies, state-of-the-art

development technologies, and modern

manufacturing processes, Siemens sus-

tainably maintains its leading position

in the field of vacuum circuit-breakers.

With Siemens products, the performance,

reliability and economic efficiency of the

entire switchgear assembly grows, and

life-cycle costs are reduced.

Over 40 years of experience

in vacuum switching technology

In particular, Siemens has perfected its

vacuum circuit-breakers for generator

switching applications, where they are

subjected to high thermal and mechanical

stress:

Special contact material for minimum

contact wear

Specifically developed contact system

Optimized design for efficient cooling

Post insulator construction for highest

mechanical stability

Safe breaking operations by controlling

long arcing times even in case of

missing zero crossings

Transient recovery voltages with high

rates-of-rise, typical for generators, are

controlled without additional capacitor

circuits

Application of the proven vacuum switch-

ing technology is thus possible with everincreasing ratings, which formerly had

to be implemented with SF6switching

technology.

Vacuum switching technology

established on the market

The exceptional economic and techno-

logical aspects of the vacuum quenching

principle have made the vacuum circuit-

breaker the device that is mostly used

worldwide for voltage ratings from

1 kV to 52 kV.

In the last years, the application of

the vacuum switching technology has

expanded to very high current ratings,

and it is largely accepted even in the

field of generator switching duties.

Siemens offers a wide range of vacuum

circuit-breakers for generator switching.

Whether it be vacuum interrupters,

vacuum circuit-breakers, or complete

switchgear assemblies: Siemens

offers the suitable solution for

every requirement.

Convincing all along the lineSwitchgear and switching devices from Siemens

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Advantages of arc extinctionin the vacuum

Vacuum circuit-breakers have a mini-

mum arc power, as there is only contact

material, but no ionisable medium avail-able. The arc already extinguishes at a

minimum contact distance (23 mm).

Near current zero, the arc power is notsufficient to maintain the plasma. The

current is interrupted. With this contact

distance, the dielectric recovery of the

contact gap is enough to assume thetransient recovery voltage.

Features of theSiemens vacuum switching technologyConstant dielectric

The hermetically closed vacuum interrupters are

insensitive to environmental influences Switching processes in the vacuum do not produce

any decomposition products as this is the case with

SF6circuit-breakers

Constant contact resistance

As there is no oxidation in the vacuum,

the contact surfaces remain metallically pure

The very small contact resistance prevailsthroughout the entire service life

Separate main and arcing contacts, such as

required for SF6circuit-breakers, are not necessary

Suitable for all switching duties

Small chopping currents

Free of restrikes Breaking of highest normal and short-circuit currents

Economic advantages

Vacuum interrupters are maintenance-free

Modern vacuum circuit-breakers are maintenance-free

up to 10,000 operating cycles

High reliability of vacuum circuit-breakers

Low number of moving parts inside the arcing chamber

Extremely high mean-time-to-failure (MTTF) values

of the vacuum interrupters

Minimum use of plastic materialin vacuum circuit-breakers

Air is the main insulator

Avoidance of creepage paths and partial discharges

Safety first

In the extremely unlikely case of loss of vacuum,only an arc develops, as the current is interruptedinside a ceramic-metal housing

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Type-tested according to all relevant standards

Type tests as specified in IEC 62271-100 are performed as a rule for

all Siemens circuit-breakers. Generator circuit-breakers are additionally

tested in accordance with IEEE C37.013. This North American

ANSI Standard is the only worldwide standard to take into account

the increased requirements to which the devices are subjected when

switching generators. As a result, ANSI has also become the leading

standard for generator circuit-breakers in IEC-oriented professional

circles.

Standard IEEE C37.013 includes in particular:

For generator-side faults: High DC components

and the resulting missing zero crossings

For system-side faults: Higher TRV rates-of-rise

Higher test voltage levels

Proven quality from Siemens

Classic design Phase-segregated design

17.5 kV

360 MVA

240 MVA

180 MVA

120 MVA

100 MVA

In

12,000 A

8,000 A

6,300 A

4,000 A

3,150 A

40 kA 50 kA 63 kA 72 kA 80 kA 90 kA Ik

3AH371

3AH381

3AH373

3AH375

3AK763

Vacuum circuit-breakers for generator switching applications up to 17.5 kV

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Reliable switching capacity up to 90 kA resp.

a rated normal current of 12,000 A

Today, in numerous power supply companies worldwide, the high-current

and generator circuit-breaker 3AH38 is standard for breaking normal currents

up to 4,000 A. It is the first vacuum circuit-breaker with 63 kA and 72 kA to

be type-tested according to the criteria of generator circuit-breaker standard

IEEE C37.013.

Its counterpart for higher generator ratings is 3AH37, the first vacuum circuit-

breaker worldwide which can carry a normal current of 6,300 A on a sustained

basis up to 24 kV without forced cooling. Moreover, at a voltage level of 24 kV

it controls short-circuit currents up to 72 kA with forced cooling, the 3AH37

can be operated with normal currents up to 8,000 A.

Being optimized for interconnected operation, the circuit-breakers can be

used in switchgear with enclosed phases, and flexibly in retrofit business.Hereby, highest normal currents up to 12,000 A with a short-circuit breaking

capacity of 80 kA, and up to 6,300 A at 90 kA are reached.

3AH37 and 3AH38

Classic design Phase-segregated design

24 kV

500 MVA

330 MVA

260 MVA

160 MVA

130 MVA

In

12,000 A

8,000 A

6,300 A

4,000 A

3,150 A

50 kA 63 kA 72 kA 80 kA 90 kA Ik

3AH374

3AH376

3AH371

with forced cooling

Vacuum circuit-breakers for generator switching applications up to 24 kV

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Compact design high performance

Due to its pole shells with a pole-centre

distance of only 210 mm, the 3AK7

combines high mechanical resistance

with a very compact design, and is thus

perfectly suitable for use in compact

switchgear.

As the construction is almost identical

with 3AK7 IEC 50 kA, it offers a profit-

able opportunity for switchgear manu-

facturers to cover also smaller generator

switching applications besides the

IEC high-current market. The 3AK763

is designed for 10,000 mechanical oper-

ating cycles and type-tested according

to IEEE C37.013.

3AK763The compact vacuum circuit-breaker for generator switching applications

Rated short-circuit breaking current ISC(3s) [kA] 40

DC component of the rated short-circuit breaking current [%] 75

Asymmetrical breaking current [kA] 58

Rated short-circuit making current [kA] 110

Generator short-circuit breaking current ISC gen [kA] 20

DC component of the short-circuit breaking current [%] 117


Rated currents [A] 1,250; 2,000; 2,500; 3,150; 4,000 (with forced cooling)

Rated voltage 17.5 kV(IEC 62271); 15 kV(IEEE C37.013a)

50/60 Hz; Up= 95 kV; Ud= 38 kV3AK763

Rated operating sequence

at short-circuit breaking current CO 30 min CO, up to 30 short-circuit breaking operations

Further operating sequences possible:

O 3 min CO 3 min CO,

at normal current O 3 min CO 3 min CO, up to 10,000 operating cycles

Up= Rated lightning impulse withstand voltage Ud= Rated short-duration power-frequency withstand voltage

The 3AK is used, for example,in the Siemens switchgear type

NXAirP for generator switching.

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For generator switching applications

with designs where the phases aresegregated, the requirements for pole

synchronism have been implemented

according to IEC 62271-100, and testedwith short-circuit currents up to 80 kA

and normal currents up to 12,000 A.

The three-circuit-breaker solution is also used as a single-phase enclosed designin the Siemens switchgear type HB3.

3AH37The three-circuit-breaker solution for phase-segregated design

Rated short-circuit breaking current ISC(3s) [kA] 50 63 72 80

DC component of the rated short-circuit breaking current [%] 75 65 65 65

Asymmetrical breaking current [kA] 73 86 98 109

Rated short-circuit making current [kA] 137 173 197 219

Generator short-circuit breaking current ISC gen [kA] 25 31.5 36 40

DC component of the short-circuit breaking current [%] 110 130 110 110

Asymmetrical breaking current [kA] 46 66 67 74

Rated currents [A] 4,000; 5,000; 6,300; 8,000; 10,000; 12,000Rated voltage 17.5 kV(IEC 62271); 15.5 kV(IEEE C37.013a)

50/60 Hz; Up= 110 kV; Ud= 50 kV3AH3732 3AH3733 3AH3734 3AH3735

Rated voltage 24 kV(IEC 62271; IEEE C37.013a)

50/60 Hz; Up= 125 kV; Ud= 60 kV3AH3742 3AH3743 3AH3744 3AH3745


at shor t-circuit breaking current CO 30 min CO, up to 30 shor t-circuit breaking operations





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Example for a retrofit installation: Replacement of compressed-airgenerator circuit-breakers (6 kV 86.5 kA 3,500 A)

Rated short-circuit breaking current ISC(3s) [kA] 90

DC component of the rated short-circuit breaking current [%] 45


Rated short-circuit making current [kA] 247

Generator short-circuit breaking current ISC gen [kA] 45

DC component of the short-circuit breaking current [%] 110


Rated currents [A] 4,000; 5,000; 6,300

Rated voltage 17.5 kV(IEC 62271); 15.5 kV (IEEE C37.013a)

50/60 Hz; Up= 110 kV; Ud= 50 kV3AH3756

Rated voltage 24 kV(IEC 62271; IEEE C37.013a)

50/60 Hz; Up= 125 kV; Ud= 60 kV3AH3766


at short-circuit breaking current CO 30 min CO, up to 30 short-circuit breaking operations





In order to control generator switching appli-

cations up to 90 kA, this circuit-breaker was

developed based on the well-known 3AH37

operating mechanism, and an advanced

vacuum interrupter was installed.

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More than a good technologyThe Siemens performance portfolio from customer advice to reliable switchgear

Correct selection of the

generator circuit-breaker

Selection criteria are: Rated voltage

Rated current

System-side short circuit

Generator-side short circuit

Design for normal operation

In the vicinity of generators, specialconditions arise. Thus, every application

is specifically adapted to the customers

requirements.

Basis for the solutions is the application

guide in IEEE C37.013.

Design for the case of faultIn general, the symmetrical system-side

short-circuit current (case of fault a)

is higher than the generator-side short-

circuit current (case of fault b), andtherefore determines the required

breaking capacity of the generator

circuit-breaker.

Fault location a: System-side short-circuit

with permanent AC component

Fault location b: Generator-side short-circuit

with missing zero crossing

In the case of fault, two dif ferent fault current components overlap.The short-circuit current component to be interrupted is supplied by

a) High-voltage system or

b) Generator orc) High-voltage system and generator

Auxiliary

transformer

System

transformer

C)b)

a)

G

The DC component of the generator-

side short-circuit current is higher,

which must also be taken into account

for assessment of the breaking capacity.

Overvoltage protection measures

From the view of the vacuum switchingprinciple, no overvoltage protection

measures are necessary for switching

generators, unless the short-circuit

current of the generator is smallerthan 600 A. However, surge arresters

are usually equipped for this switching

application in order to protect the

expensive generators from all otherovervoltages.

Sectional view of a vacuuminterrupter

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100

80

60

40

20

0

20

40

60

80

100

isc(t)

(kA)

0.000 0.020 0.040 0.060

Time (s)

0.080 0.100

Three-phase short-circuit current

Phase T first-pole-to-clear

Isc=20.2 kA

DC 59%

tarc total=11 ms

tarc min=4.4 ms

Contact separation

tcp=49 ms

Isc=24.2 kA

Isc=20.4 kA

1stzero crossing

R

S

T

Basic representation of the analysis for the case of fault

For this purpose, we kindly ask you

to submit the following data:

Data sheets of:

Generator Transformer

Auxiliary transformer & motors,

if applicable

Single-line diagram

Information on equipment operation,

e.g. interconnected circuits

Based on the information concerning

your application, our experts select a

circuit-breaker which reliably controls

all service conditions, including tripping

in case of fault.

Among other things, the result of the

calculations contains a graphical repre-

sentation of the current characteristics,

as shown below:

You know your application.And we know the behaviourand features of our switchingdevices.

Together we work out theperfect solution for yourapplication.

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More than 1,300 systems are installedin generator switching applicationsworldwide

Siemens AG

Infrastructure & Cities Sector

Low and Medium Voltage Division

P.O. Box 3240

91050 Erlangen, Germany

For more information, please contact

our Customer Support Center.

Phone: +49 180 524 8437

Fax: +49 180 524 2471

(Charges depending on provider)

E-mail: [email protected]

Siemens AG 2013

Printed in Germany

TH 260-120542 WS 04131.0

All rights reserved.

Trademarks mentioned in this

document are the property

of Siemens AG, its affiliates,

or their respective owners.

Subject to change without prior notice.The information in this document

contains general descriptions of

the technical options available,

which do not always have to be

present in individual cases. The

required features should therefore

be specified in each individual case

at the time of closing the contract.

Order No. IC1000-G310-A100-X-7600

130405-buj vakuum generatorschalter en

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