130405-buj vakuum generatorschalter en
TRANSCRIPT
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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
Asymmetrical breaking current [kA] 39
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
Rated operating sequence
at shor t-circuit breaking current CO 30 min CO, up to 30 shor t-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
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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
Asymmetrical breaking current [kA] 107
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
Asymmetrical breaking current [kA] 83
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
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
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