Generator Circuit-Breaker Systems
HECS, HEC 7/8
Data and Dimensions
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ABB
Contents
Application
Characteristics
Standards and quality
Modular design concept
Equipment options
Generator circuit-breaker
Disconnector
Earthing switch
Starting switch
Short-circuiting connection
Current transformer
Voltage transformer
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3
3
4
5
5
8
9
9
9
10
10
Surge arrester
Surge capacitor
Terminals
Phase enclosure
Control and supervision
Tests
Transport to site
Site erection and commissioning
Maintenance and overhaul
Dimensions
Technical data
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10
11
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12
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Application
The Generator Circuit-Breaker System type HECS and
HEC 7/8 has been developed as a system suitable for
application in all types of power plants.
The HECS and HEC 7/8 Generator Circuit-Breaker
Systems are also suitable for retrofitting in existing
power plants, when these are modernised, extended
and/or automated. It is available for both indoor and
outdoor application.
Characteristics
• 3-phase system with a SF6 circuit-breaker and disconnector in series with the circuit-breaker, in single-phase enclosures, supplied fully assembled on a
common frame, with operating mechanisms, supervisory and control equipment.
• Additional components as earthing switches, starting switch (for starting of gas-turbines), current- and
voltage transformers, surge capacitors, surge arrester,
all integrated and mounted in the phase enclosures,
can be provided. Additionally the earthing switch
on the breaker side of the HECS Generator CircuitBreaker System (if equipped with an optional short-
circuiting bar) can be used as a short-circuiting link
during power plant protection setting, whereas the
HEC 7/8 for this purpose can be equipped with a
short circuiting connection which is either manually
mounted or motor operated.
• The phase distance can be selected to suit the busbar spacing in the power plant.
Standards and quality
The Generator Circuit-Breaker System type HECS and
HEC 7/8 fulfil the requirements of all relevant standards, i.e. IEEE (ANSI) Std C37.013 and IEC 60694, IEC
62271-102, IEC 60044-1/2, IEC 60099-4, IEC 60358, IEC
60529, IEC 61166.
ABB
ABB High Voltage Products is continuously endeavoured to improve its quality-assurance-system; this has
been recently new assessed by The Swiss Association
for Quality and Management Systems with the SQScertificate ISO 9001 / ISO 14001.
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Modular design concept
The standard design includes:
• SF6 circuit-breaker and disconnector
• Earthing switches on one or both sides (for HECS:
on breaker side also optional available with shortcircuit bar to be used as short-circuiting link)
• Current transformers on one or both sides with up
to three cores per current transformer (depending
on the class)
As required by the plant layout, individual components can be deleted from the standard execution.
The standard execution can be extended by the following optional items:
• For HECS: Short-circuiting connection - either in
connection with generator side earthing switch, or
to be manually mounted (for power plant protection
setting)
• Voltage transformers on one or both sides with one
or two secondary windings
• For HEC 7/8: Short-circuiting connection - either
permanently fitted with switch, or to be manually
mounted (for power plant protection setting)
• Starting switch for (reduced voltage) starting the gas
turboset via SFC (Static Frequency Converter)
• Surge arrester on transformer side.
• Surge capacitors on both sides.
View into one pole of circuit-breaker type HECS-130L
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ABB
Equipment options
1
Generator circuit-breaker
6
Surge capacitor
2
Line disconnect switch
7
Current transformers
3
Earthing switch
8
Voltage transformers
4
Starting switch for SFC connection
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Surge arrester
5
Manual short-circuiting connection (by removal of
cover)
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Motor-operated short circuiting link (only HECS
with generator side earthing switch)
Generator circuit-breaker
Interrupting chamber
Within the interrupting chamber SF6-gas is used for
both arc extinguishing and internal insulation. The
external insulation is air.
For the interruption a combination of the self-extinguishing and the puffer principle is used, a design
optimised to achieve a significant reduction in operating energy.
This self-pressurising principle allows high breaking
capacities as well as almost overvoltage-free interruption of small (inductive) currents.
Separate contact systems for breaking and for continuous current carrying are used. This avoids wear / erosion of the continuous current contacts and ensures
trouble-free current carrying even after a large number
of operations.
ABB
Interrupting chamber of the circuit-breaker type HECS-100L. On the
left the terminal is visible. The circuit-breaker contacts are operated
by a shaft passing from below, through the vertical support insulator.
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Mode of operation of the interrupting chamber of the HECS circuit-breaker systems
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a Circuit-breaker “CLOSED”
b Initiation of opening movement, (transfer of current from the
main contacts to the arcing contacts)
2
3
4
a
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6
c Separation of arcing contacts with interruption of small currents supported by puffer action
b
5
2
d Separation of arcing contacts with interruption of large currents – supported by the thermal effect of the current arc
itself to build up the pressure in the heating volume
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e Circuit-breaker “OPEN”
1
c
d
7
6
5
4
9
8
e
1 Terminals
6 Moving main contact
2 Cylindrical coil
7 Puffer
3 Fixed arcing contact
8 Heating volume
4 Moving arcing contact
9 Gas compartment
5 Fixed main contacts
Hydraulic spring drive
The hydraulic spring operating mechanism combines
the advantages of a hydraulic operating mechanism
with those of a spring energy storage system. Energy
storage is accomplished with the aid of a disk spring
assembly, with the advantages of high long-term stability, reliability and non-influence of temperature
changes. Tripping of the operating mechanism and
energy output are based on proven design elements
of the hydraulic operating technique, such as control
valves and hydraulic cylinders.
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1
O
I
M
M
2
High pressure
Low pressure
2
1 Breaker operating rod
2 Energy storage device
Schematic diagram of the hydraulic spring operating mechanism
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The operating mechanism is based on the so-called
differential piston principle (between the larger piston head side area and the smaller piston rod side
area). For the closing operation the piston head side
is isolated from the low pressure and simultaneously
connected to the high pressure oil volume. As long as
the pressure is maintained, the piston remains in the
“CLOSED” position. A pressure controlled mechanical interlock prevents movement of the piston to the
“OPEN” position in case of a pressure drop.
View of the hydraulic spring operating mechanism
ABB
For the opening operation, the piston head side is isolated from the high pressure and simultaneously connected to the low pressure oil volume.
The charging state of the spring disk assembly is controlled by switching elements, actuating the pump
motor to immediately maintain the oil pressure. For
emergency use or maintenance, charging of the spring
disk assembly and tripping is possible locally. The
fully integrated construction has no hydraulic pipe
connections of any kind.
A non-return valve between pump and high-pressure oil volume prevents pressure loss in the event
of a pump outage. The hydraulic system is hermetically sealed against atmosphere (no corrosion). The
mechanically operated position indicator provides reliable indication of the circuit-breaker position.
The drive operates all three breaker poles simultaneously by mechanical linkages, thus keeping the
switching time difference between the poles to a minimum.
SF6-gas density monitoring system
The breaking capacity of an SF6 circuit-breaker and the
dielectric withstand level across its open contacts is
dependent upon the density of the SF6-gas. Under the
condition of constant volume the gas density is independent of the gas temperature, while the pressure
varies with the temperature. It is therefore more practical to measure and use the gas density rather than the
pressure for circuit-breaker supervisory purposes.
The functional principle of the density monitor is
shown in below diagram. The density monitor operates according to the reference-volume-density principle. The density of the gas in the circuit-breaker chamber is compared with the density of the gas in a sealed
reference gas volume. When the gas density drops
below the specified value, the density monitor signals
the loss of SF6-gas in several steps.
It is mounted on the crankcase of the middle pole.
Since the gas volumes of the three breaker poles are
connected via the refilling pipe only one SF6-gas density monitor per breaker is required to supervise the
gas density.
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5
SF6-gas density indication and filling connection
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900
850
900
p [kPa]
750
700
650
600
550
500
450
p [kPa]
850
800
4
800
750
3
700
2
650
1
600
550
Schematic diagram of the SF6-gas density monitor
500
1 Pressure connection
2 SF6-gas volume of the
circuit-breaker
3 Metallic bellows
450
400
-40 -30 -20 -10
400
-40 -30 -20 -10
0
0
10 20 30
10 20 30
40 50 60 70
t [°C]
40 50 60 70
80 90 100
4 Reference gas volume
5 Actuating rod
6 Microswitch
80 90 100
P/t-diagram for SF6-gas, with operating characteristics of the gas
[°C]
density monitor for the SF6 tcircuit-breaker
Rated filling density 40.7 kg/m3
Alarm density 36.1 kg/m3
Blocking density 34.7 kg/m3
ABB
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Disconnector
The switchgear concept provides a disconnector fitted
in series with the circuit-breaker. It is placed on the
out-going side of circuit-breaker and within the same
enclosure.
The disconnector is a tubular telescopic unit, with the
moving contact on the terminal side and fixed contact
tube on the circuit-breaker side. This layout provides
easy access and simplifies maintenance.
In the open position of the disconnector the isolating
air distance can be clearly seen through an inspection
window in the side wall (HECS) or in the cover (HEC
7/8) of the enclosure. The moving contact is motor
driven.
View through the inspection window of HECS to assure that the disconnect switch is in the open position.
The operating mechanism is a compact subassembly,
including the motor, auxilary switch, reduction gear
box and coupling flanges in one unit.
Key locking in the positions “CLOSE” and “OPEN” is a
standard facility. An additional locking prevents motor
operation while the disconnector is being manually
operated. Mechanically driven position indicator is
provided in a readily visible position and a crank handle is provided for manual operation.
The operating mechanisms, as for disconnector, earthing switch,
starting switch are shown, the operating mechanisms for disconnector and all switches are identical and integrated in the pole frame.
They incorporate a driving motor and gearing, a mechanical semaphore, key locking and an electrical auxilary switch.
The sticker shows the different operation modes of the key locking
scheme of the individual motor operating mechanisms, which all of
them operate in the same way.
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ABB
Earthing switch
The earthing switch can be provided on either one or both
sides of the system. The switch and its connections are
designed for protective earthing purposes, i.e. it is rated for
the full fault current but has no current making or continuous carrying capacity.
Design is of a blade type with the hinge point connected
to the enclosure and the fixed contact to the current path.
The earthing connection is made via the system enclosure,
which is earthed at one end to the busbar enclosure. The
moving contact is motor driven.
Starting switch
The starting switch can be provided on the generator side
of the system. The starting switch and its connections have
been designed for the voltage, current and current-duration
occurring during the SFC (Static Frequency Converter) startup period of the gas turboset. The design is of a blade type
with the fixed contacts at the current path and the hinge
point isolated from the enclosure. High voltage cables can
be connected to this. The moving contact is motor driven.
Breaker type HECS
Earthing switch in closed position.
Short-circuiting connection
For the HEC 7/8 there is either a manual short circuiting
connection or an electrical operated short-circuiting switch
available.
The manual short-circuiting connection can be provided
for the use between the circuit-breaker and the disconnector of the system. This arrangement has been designed for
installations where the short-circuiting facility is only rarely
used. The short-circuiting connection is built for the voltage, current and current duration occurring during the testing and adjustment of the power plant protection system.
The cover of each of the phase enclosures has to be
removed to allow the fitting of the short-circuiting busbar.
from the enclosure (2000 V), and is protected against
inadvertently touching.
The moving contact is motor driven. As an additional feature, a link can be provided with which the short-circuit
connection can be connected to the phase enclosure i.e.,
to earth. This link can only be fitted manually.
The short-circuiting switch can be provided between the
circuit-breaker and the disconnector of the system. The
short-circuiting switch and its connection between phases
have been developed to expedite the testing and adjustment of the power plant protection system. Closure of the
switch establishes an unearthed three phase short-circuit,
which then can be switched to the generator terminals by
closure of the circuit-breaker.
The design of the switch is of a sliding type with the moving contact isolated from the enclosure and the fixed contact connected to the current path.
The actual short-circuiting connection between the phases
is established external to the enclosure and being insulated
Alternatively there is a motor operated short-circuiting
connection available for the HECS. If a motor operated
short-circuit connection is required, the three poles of the
earthing switch on the breaker side are linked together to
a common bar, which is connected by a copper bracket
to the enclosure of the middle phase and thereby grounded. By removing this bracket (to be done manually) and
closing of the earthing switch an unearthed three phase
short-circuit is established. The closing of the earthing
switch can be done motor operated (local/remote switch
in position local) while the generator is de-excited and the
residual voltage of the generator does not exceed 350 V.
ABB
For the HECS there is also a manual short circuiting connection available which needs to be connected between
the circuit breaker and the disconnector. The cover of
each of the phase enclosures has to be removed to allow
the fitting of the short-circuiting busbar.
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Current transformer
A ring core current transformer can be provided
on either one or both sides of the breaker system.
Depending on the class up to three cores per current
transformer can be accommodated, depending on
output and class required. The secondary windings
are permanently wired back to terminal blocks in the
control cubicle.
Voltage transformer
Ring core current transformers with up to 3 cores per transformer can
be mounted at each end of each phase enclosure.
Single-phase, cast resin voltage transformers can be
provided on either one or both sides of the breaker
system. Up to three voltage transformers or two voltage transformers and one surge arrester can be fitted
at each side and each voltage transformer can be supplied with one or two secondary windings, depending
on the class and output power required. The secondary windings are permanently wired back to terminal
blocks in the control cubicle.
Surge arrester
A surge arrester can be fitted on the transformer side, to
provide protection for transformer and generator against
overvoltages. Standard is an ABB metal-oxide surge arrester of the POLIM range with silicon housing. Metal-oxide
resistors have a highly non-linear resistance characteristic.
At service voltage a predominantly capacitive current
of < 1mA flows. Any voltage increase leads to a rapid
increase of the current, thereby limiting any further rise
in the voltage. When the voltage decreases, the condition
reverts to its essential non-conducting state. Metal-oxide
surge arresters are characterised by the residual voltage,
i.e. the voltage during the passage of an impulse current.
The voltage transformers are fitted on the side panel of the phase
enclosure.
The surge arrester is fitted on the side panel of the phase enclosure.
Surge capacitor
Surge capacitors are fitted on both sides of the breaker
system, to provide additional protection against overvoltages and to support arc extinction in the circuitbreaker by TRV limitation.
The surge capacitors are fitted outside the phase
enclosure with only the porcelain bushings protruding
into the phase enclosure.
Surge capacitor are installed in such a manner that only their porcelain bushings protrude into the phase enclosure.
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ABB
Terminals
The current path of the system is connected to the
busbar current path by bolted flexible, laminated or
stranded connectors.
In order to avoid detrimental tensile stresses to the
terminals, resulting from electro-dynamic forces of a
short-circuit current, the flexible connectors must be
supported at the midpoint by a ring having the same
diameter as the terminals. These rings reduce the con-
traction of the flexible connectors and the subsequent
tensile forces on switchgear components, under shortcircuit current conditions.
Note: The flexible connectors are not part of the scope of supply
of the GCB system, usually they are supplied by the IPB supplier.
Phase enclosure
The phase enclosures are designed to carry the induced
reverse current, flowing through the isolated phase busbar enclosures. Thus the external magnetic field and its
influence to the equipment is minimised. As standard, the
phase enclosure is welded onto the busbar enclosure,
ensuring continuity of the phase enclosure characteristics.
On the other hand, the phase enclosures effectively eliminate any possibilty of accidental contact with live components. In order to avoid pollution due to ingress of dust
and/or moisture, the phase enclosures are made airtight to
withstand also a small internal overpressure. Windows are
provided in the phase enclosures near to the disconnector, earthing switches and starting switch, to allow visually
checking of the position of each of them.
Control and supervision
Phase enclosures and control cubicle of GCB system type HECS-130L
Phase enclosures and control cubicle of GCB system type HEC 7/8
All control and supervisory apparatuses are mounted
in the control cubicle. The control cubicle is placed on
the operating mechanism side of the system above the
operating mechanism of the circuit-breaker and is not
mechanically connected with the common frame of
the breaker system.
An active mimic diagram is provided with the actual
position indications and the integrated local control of
the circuit-breaker and all other switching apparatuses.
It is mounted in the door panel behind the glass door
of the control cubicle.
In the control cubicle there are also installed a local/
remote change-over switch and counters for C-O operations of the circuit-breaker and pump startings of the
circuit-breaker drive.
Mimic board of the control cubicle
ABB
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Tests
Type tests
Routine tests
The performance of the generator circuit-breaker system was fully tested by the High Power Laboratory of
KEMA/Netherlands in accordance to the standard IEEE
C37.013 with regard to the interrupting capability.
After production, but prior to dispatch, the system is
subject to an extensive test program, as:
Further type tests were carried out with all of the
related components within the system to prove continuous current capability, dielectric strength, long
term endurance, noise level etc. and verify the liability
and compliance with the requirements of the relevant
IEC-standards.
• Design and visual checks
• Dielectric tests on the main circuit
• Dielectric tests on auxiliary and control circuits
• Measurements of the resistance of the main circuit
• Mechanical operation tests
• Timing tests and recording the switching times and
movement of breaker contacts
• Functional tests of individual components
• Leakage test of phase enclosures
• SF6-gas leakage test.
Transport to site
The entire system is fully assembled and tested together with all its ancillary equipment in the factory.
It is hence dispatched from the factory and transported
to site as a single unit.
Note: Exception - control cubicle according to ANSI standard.
Site erection and commissioning
Site erection requires a well prepared foundation.
Due to the fact, that the system is delivered as a single, fully assembled, wired and tested unit, the time,
required for erection, testing and commissioning is
extremely short.
The only substantial site work is the welding of the
enclosures onto the busbar enclosures, the mounting
of the flexible high-current connections, the connecting of the electrical supply cables and the performing
of the commissioning tests.
Maintenance and overhaul
The HECS and HEC 7/8 generator circuit-breaker systems are maintenance-free to a wide extend.
Overhaul can be scheduled based on service time,
number of C/O-operations or number of current interruptions. Removal of the phase enclosure top covers
provides easy access to the active components of each
phase, including the instrument transformers, surge
capacitors and surge arrester.
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The contact erosion can be measured without opening the interrupting chamber with the DRM-methode
(Dynamic Resistance Measurement), which has been
specifically developed for generator circuit-breakers by
ABB High Voltage Products. This allows to optimise
the service intervals also for frequent switching of
higher service currents. The DRM-Measurement system
can be ordered separately.
ABB
Dimensions
Type HECS
Type HEC 7/8
ABB
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Technical data
Generator circuit-breaker system type
General:
Rated maximum voltage
Rated frequency
HECS-80
HECS-100
HECS-130
kV
Hz
23
50/60
25.3
50/60
25.3
50/60
10500
13000
18000
13000
18000
10000
12000
17000
12000
17000
Rated continuous current 50 Hz
Rated continuous current 50 Hz
Rated continuous current 50 Hz
Rated continuous current 50 Hz
S
M
L
XL*
A rms
A rms
A rms
A rms
8500
10500
Rated continuous current 60 Hz
Rated continuous current 60 Hz
Rated continuous current 60 Hz
Rated continuous current 60 Hz
S
M
L
XL*
A rms
A rms
A rms
A rms
8000
10000
Rated insulation level:
Rated power frequency withstand voltage
to earth and across circuit-breaker/switch contacts
across isolating distance of disconnector
Rated lightning impulse withstand voltage
to earth and across circuit-breaker/switch contacts *)
across isolating distance of disconnector
Circuit-breaker:
Rated peak withstand current
Rated short-time withstand current
Rated short-circuit making current
Rated short-circuit breaking current
Rated operating sequence
Rated interrupting time
kV rms
kV rms
60
70
60
70
60
70
kV peak
kV peak
125
145
125
145
125
145
kA peak
kA, 3 s
kA peak
kA rms
220
80
220
80
360
130
360
130
67
280
100
280
100
CO-30min-CO
67
ms
67
Disconnector:
Rated peak withstand current
Rated short-time withstand current
Operating time
kA peak
kA, 3 s
s
220
80
2
280
100
2
360
130
2
Earthing Switch:
Rated peak withstand current
Rated short-time withstand current
Operating time
kA peak
kA, 1 s
s
220
80
2
280
100
2
360
130
2
The above data are not limiting values. Additional data on request. We reserve the right to alter data and technical details without notice.
14
ABB
Generator circuit-breaker system type
General:
Rated maximum voltage
Rated frequency
Rated continuous current
Rated insulation level:
Rated power frequency withstand voltage
to earth and across circuit-breaker/switch contacts
across isolating distance of disconnector
Rated lightning impulse withstand voltage
to earth and across circuit-breaker/switch contacts
across isolating distance of disconnector
Circuit-breaker:
Rated peak withstand current
Rated short-time withstand current
Rated short-circuit making current
Rated short-circuit breaking current
Rated operating sequence
Rated interrupting time
HEC 7
HEC 8
kV rms
Hz
kA
30
50/60
24/22
30
50/60
28/26
kV rms
kV rms
80
88
80
88
kV peak
kV peak
150
165
150
165
kA peak
kA, 1 s
kA peak
kA rms
ms
600
600
220
220
440
440
160*)
160*)
CO-30min-CO
56
56
Disconnector:
Rated peak withstand current
Rated short-time withstand current
Operating time
kA peak
kA, 1 s
s
600
220
2
600
220
2
Earthing Switch:
Rated peak withstand current
Rated short-time withstand current
Operating time
kA peak
kA, 1 s
s
440
160
2
440
160
2
*) higher ratings on request
The above data are not limiting values. Additional data on request. We reserve the right to alter data and technical details without notice.
ABB
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ABB Switzerland Ltd
High Voltage Products
Brown Boveri Strasse 5
CH-8050 Zurich / Switzerland
Phone: +41 58 58 83424
Fax:
+41 58 58 81644
www.abb.com
1HC0023255 E01 / AC05
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