Hybrid circuit breaker

L. E. College, Morbi
GUJARAT TECHNOLOGICAL UNIVERSITY

“HYBRID CIRCUIT BREAKER”
A Product survey Report On
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF THE DEGREE OF

BACHELOR OF ENGINEERING
Electrical Engineering

SUBMITTED TO:
L. E. COLLEGE, MORBI

SUBMITTED BY
Student Name

Enrollment No.

1. Bhimani Vishal R.

100310109056

2. Patel Priyesh B.

100310109059

GUIDED BY:Prof. S. N. Purohit
Assi. Prof. Electrical Department
October 2013

1
L.E. COLLEGE - MORBI

Lukhdhirji Engineering College, Morbi
Gujarat Technological University

CERTIFICATE

This is to certify that
1. Bhimani Vishal R.

(100310109056)

2. Patel Priyesh B.

(100310109059)

of final year Electrical Engineering students have satisfactorily and accurately completed
their project work entitled “Product survey on Hybrid Circuit Breaker” for the subject
code 170001 Project I in the 7th semester of academic year 2013-14 for the partial fulfilment
of the award of the Bachelor of Engineering in Electrical Engineering at Gujarat
Technological University.

DATE:-

PROF. S. N. PUROHIT

PROF. A. K. JOSHI

PROJECT GUIDE

HEAD OF DEPARTMENT

2

ACKNOWLEDGEMENT
We owe a great many thanks to a great many people who helped and
supported us during the

writing of this

report. Our deepest thanks to

S.N.Purohit the Guide of the project for guiding and correcting various
documents of ours with attention and care. He has taken pain to go through the
project and make necessary correction as and when needed. We express our
gratitude to our head of the Department Prof A.K.JOSHI for his invaluable
support and encouragement at every stage. We also express our thanks to the
Principal Prof. P. C. Vasani ,Lukhdhirji Engineering College, Morbi-2, for his
constant support and encouragement. We would also thank our Institution and
the faculty members without whom this project would have been a distant
reality.

Name

Sign

Bhimani Vishal R.
Patel Priyesh B.

3

ABSTRACT:
High Voltage Circuit Breaker (CB) is important electrical equipment used in the power
system network to isolate the faulty section from the healthy network and thus ensure safe
operation of the electrical system. Vacuum Circuit Breakers and SF6 Circuit Breakers are
widely used depending upon the power rating of the transmission line. The merits and
demerits of the two are reviewed and the need for hybrid model is analyzed.

The hybrid circuit breaker has at least two series-connected arcing chambers, which are
operated by a common drive via a transmissionconnected upstream from it. It is intended to
be possible to assemble this transmission easily in the interior of the hybrid circuit breaker.
This is achieved in that the transmission is formed from at least two transmission parts which
can be plugged together, with a first transmission part being firmly connected to the at least
one first arcing chamber and a second transmission part being firmly connected to the at least
one second arcing chamber. The transmission also has means which allow the movements of
the at least two arcing chambers to be technically suitably matched to one another and to be
optimized with respect to the time sequence and switching speed thereof.

A hybrid circuit breaker consists of a series-connected vacuum interrupter and sulfur
hexafluoride interrupter wherein the contacts of each are simultaneously operated. The sulfur
hexafluoride interrupter is of the type in which an arc is rapidly rotated through a relatively
static volume of sulfur hexafluoride. In one embodiment of the invention, the vacuum
interrupter is replaced by a second sulfur hexafluoride interrupter in which the arc gap
between the electrodes receiving the final arc to be interrupted is relatively smaller than the
corresponding arc gap in the other sulfur hexafluoride interrupter.

4

INDEX:PAGE NO.
CHAPTER 1: INTRODUCTION…………………………………………….7

CHAPTER 2: HYBRID CIRCUIT BREAKER (AC)……………………….9
2.1:-DESIGN
2.2:-METHOD OF OPERATION
2.3:-CURRENT INTERRUPTION IN HYBRID MODES
2.4:-REQUIREMENTS AND OBJECTIVE

CHAPTER 3: HYBRID CIRCUIT BREAKER (HVDC)………………….14
3.1:-DESIGN OF HYBRID HVDC CIRCUIT BREAKER
3.2:-CIRCUIT DIAGRAM OF HYBRID CIRCUIT BREAKER
3.3:-PROTOTYPE DESIGN OF TH HYBRID HVDC C.B.

CHAPTER 4: TESTING OF HYBRID HVDC BREAKER………………19
4.1:-TEST RESULTS OF MAIN BREAKER
4.2:-TEST RESULTS OF HYBRID HVDC C.B.

CHAPTER 5: NEEDS OF HYBRID CIRCUIT BREAKER
AND SPECIFICATION………………….……………...24
5.1:-NEEDS OF HYBRID CIRCUIT BREAKER
5.2:-SPECIFICATION

5

CHAPTER 6: ABOUT OF INVENSION…………………………………...27
6.1:-THE OBJECT OF INVENSION
6.2:-SUMMERY OF INVENSION

CHAPTER 7: ADVAMTAGES, DISADVANTAGES, AND COST
OF HYBRID CIRCUIT BREAKER………………………29
7.1:-ADVANTAGES
7.2:-DISADVANTAGES
7.3:-COST

CHAPTER 8: PHOTO OF HYBRID BREAKER…..…….……………....31

CONCLUSION

REFERANCE

6

CHAPTER 1: INTRODUCTION
For many years various investigators have explored different approaches to develop a high
voltage direct current circuit breaker. Recently a joint effort by the Bonneville Power
Administration (BPA), Electric Power Research Institute (EPRI) and BrownBoveri
Corporation (BBC) resulted in the successful development and field testing of a practical,
500 kV, 2000A air - blast HVDC breaker. The primary focus of all HVDC breaker
development has been overcoming the problem of dc systems having no natural currentzero.
Inthe familiar high voltage ac circuit breaker, the interruption process depends on the
naturally occurring cyclic instances of current zero. The breaker will typically arc through
high current periods making no attempt to clear until or about the current zero point,
whereupon it will then isolate the circuit. To obtain similar isolation in a dc circuit, it is
necessary to create a current zero point. Most of these methods create a current zero by active
or passive commutation of the direct current.

Active commutation methods have a capacitor, typically pre-charged, inserted across the
main interrupter element through some switching device. The surge current caused by the
insertion of this capacitor quickly drives the direct current in the interrupter to zero.

The present invention relates to a hybrid circuit breaker, comprising a first circuit that
comprises: a main current path which comprises a mechanical switch element, and at least
one commutation path arranged in parallel with the main current path and comprising a
controllable semi-conductor switch element. The invention also relates to an electric power
supply system comprising a hybrid circuit breaker according to the invention. The breaker is
an electric current breaker. In particular, it may form part of an AC electric power system. In
particular, it may form part of a medium or high voltage electric power system, medium or
high voltage being referred to as a voltage of 400 V or above. However, lower voltage
applications are not excluded. The mechanical switch element may comprise any type of
mechanical switch comprising first and second contact elements that are movable in relation

7

to each other in connection to the switching operation thereof. Typically, the mechanical
switch comprises a mechanical circuit breaker.

Electric ships with Integrated Power Systems (IPS) can benefit from dc distribution
architectures that allow bi-directional power flow. One drawback has been the lack of
suitable dc circuit breakers that can operate at medium to high voltages and operate fast
enough to limit peak fault currents to acceptable levels.
General Atomics (GA) has developed a novel high voltage hybrid dc circuit breaker, Fig. that
employs a fast mechanical interrupter in parallel with a solid-state commutation circuit to
achieve short interrupt times for medium to high voltage systems.

The controllable semi-conductor switch element may be any kind of solid-state breaker based
on semi-conductor technology and of controllable character such as a controllable thyristor,
an IGBT (Insulated Gate Bipolar Transistor), an IGCT (Insulated Gate-Commutated
Thyristor) or a GTO, all well known within this field of technology. The expression
"controllable" indicates that the element in question opens or closes as soon as an appropriate
control is applied to it. Accordingly, in this regard, the controllable semi-conductor element
is an active element, or at least not passive.

8

CHAPTER 2: HYBRID CIRCUIT BREAKER (AC)
2.1:-DESIGN:
The interrupter is fundamentally a very high performance pneumo-electromechanical device.
Aside from the initial magnetic impulsive force and the reclose/contact pressure operation,
the interrupter is essentially a passive device.
However, achieving the specified voltage breakdown recovery in the specified time depends
on a complex set of coupled nonlinear actions including:

The drive circuit energy store must have sufficient energy and the drive coil must
magnetically couple to the piston in a manner that propels the piston to establish an
adequate electric gap in the specified time.
The gas specie and initial gas pressure must fill the electric gaps in the specified time
with sufficient pressure to achieve the specified breakdown strength.
The inner cylinder volume and check valve design must dissipate the kinetic energy
of the piston to arrest and latch the piston open.
And, the gas system must allow for piston reclose on command and the establishment
of an adequate contact pressure to achieve low insertion loss.

A thorough understanding of all these actions is essential to ensuring that the interrupter is
properly designed and can meet the objective requirements. The design development was
necessarily model & simulation driven, relied heavily on finite element analysis (FEA) and
computational fluid dynamic (CFD) techniques and consisted of four key analytical efforts.

1. Piston Opening Dynamics
2. Electrostatic & Voltage Recovery Analysis
3. Piston Arrest & Latch Dynamics
4. Piston Structural & Friction Analysis

9

Fig. Hybrid Circuit Breaker (AC)

2.2:-METHOD OF OPERATION:
When the interrupter receives a signal to “Open”, the interrupter controller sends a command
to the drive circuit triggering an electric discharge into the drive coil. The electric pulse in the
drive coil couples to the conducting face of the pistons which are accelerated away from the
electrodes under the Lorentz forces at very high speeds. As the contactor piston moves away
from the electrodes, the pressure builds in the inner cylinder until the check-valve opens
venting gas from the inner cylinder to the outer cylinders.
“close”, the interrupter controller signals the gas system to pump gas from the outer cylinder
to the volume of the inner cylinder between the check-valve and piston. The piston is pushed
toward the electrodes under gas pressure until
seated. When the contactor pistons are seated against the electrodes, the interrupter controller
signals the gas system to restore and maintain a specified pressure to ensure a good electrical
contact between the pistons and the electrodes.
The interrupter is now “closed” and ready to resume normal operations. The closing
sequence is illustrated in Fig. 4 „Closing Sequence‟ a-e.

10

Fig. High-speed Interrupter Open/Close Sequence

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2.3:-CURRENT INTERRUPTION IN HYBRID MODEL:
The minimum arc duration are shorter in a vacuum interrupter as compared to the SF6
interrupter by several milliseconds. Hence it is preferable to open the SF6 interrupter initially
followed by the opening of vacuum interrupter with some delay of a few milliseconds. Since
there are two interrupters connected together therefore the currents can be interrupted by
each of the interrupters.

Interruption Initially By Vacuum Interruption:
In this case, current is first interrupted by the vacuum interrupter. This mode of operation is
observed at the highest current. Vacuum interrupter first transmits initial recovery voltage
peak value and the latter higher peak value is shared by SF6 interrupter as highlighted in fig.
As can be seen in fig. ,the vacuum arc extinguishes at current zero while the SF6 arc
continues to operate for the next 5usec and then after current zero 8 A post arc current flows
in the vacuum interrupters.
When the vacuum post arc current decays to zero then only the SF6 post arc current is
forcibly chopped to zero. Due to this, the arc voltage and current do not cross zero
simultaneously and the arc voltage is initially of opposite polarity.

Interruption SimutaneouslyBy Vacuum And Sf6 Interrupter:
In this case, current is simultaneously interrupted by both vacuum and SF6 interrupters. This
mode of operation is typically observed in conditions in which current is less than maximum
current. Here, the performance of SF6 circuit breaker is reduced deliberately but it is
sufficient to do the job alone.SF6 post arc current is much smaller as compared to the
vacuum CB, so the SF6 interrupter stops the flow of vacuum arc charge. The post arc
vacuum charge remains trapped. This prevents the Transient Recovery Voltage (TRV) to
build up in vacuum interrupter until all the charges disappear Therefore the complete TRV is
carried by SF6 interrupter. The above operation can be easily seen in fig below. The
performance of the hybrid circuit breaker in the first mode is better than that in second mode.

12

Fig. SF6 and vacuum interrupt simultaneously

2.4:-REQUIREMENTS AND OBJECTIVES:
In 2011, GA proposed to the US Department of Energy’s Advanced Research Projects
Agency (ARPA-e) and was awarded a contract to develop a high-speed, high voltage, low
insertion loss hybrid circuit breaker. The objective of the project was to develop a circuit
breaker that could achieve or exceed the technical performance measures listed in Table 1
and full circuit breaker open/latch/reclose functionality.

Table 1: Interrupter Requirements Description
Description

Units

Requirement

Normal Current:

A

500

Interrupt Current, Max:

kA

< 3.5

Interrupt Time:

s

< 250

Rated Voltage:

kV

125

Insertion Loss:

W

1,000

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CHAPTER 3: HYBRID HVDC CIRCUIT BREAKER
3.1:-DESIGN OF HYBRID CIRCUIT BREAKER:
Recent studies focus on designing a hybrid circuit breaker operation mechanism with strong
controllability property and low dispersion degree. The former researchers have adopted an
operation mechanism that connects the two interrupters with the help of a connection rod or a
spring. This mechanism led to weak controllability property and low dispersion degree.
Depicts a hybrid circuit breaker based on fiber control vacuum CB connected in series with
SF6 CB.

A synchronized coordinate operation control unit which adjusts the coordination movements
of the two interrupters in microseconds is utilized in this scheme. The top bus terminal of
vacuum circuit breaker is connected with the bus input, and the end bus terminal box is
linked with top bus terminal of SF6 circuit breaker. The end bus terminal of SF6 circuit
breaker is connected to bus output, its operation mechanism and synchronization unit are
placed at low potential. The synchronization unit of hybrid circuit breaker receives system
control signal and perform synchronized operation to operate the vacuum circuit breaker and
SF6 circuit breaker respectively.

3.2;-CIRCUIT DIAGRAM OF HYBRID HVDC BREAKER:
As presented in Figure, the hybrid HVDC breaker consists of an additional branch, a bypass
formed by a semiconductor-based load commutation switch in series with a fast mechanical
disconnector. The main semiconductor-based HVDC breaker is separated into several
sections with individual arrester banks dimensioned for full voltage and current breaking
capability, whereas the load commutation switch matches lower voltage and energy
capability. After fault clearance, a disconnecting circuit breaker interrupts the residual
current and isolates the faulty line from the HVDC grid to protect the arrester banks of the
hybrid HVDC breaker from thermal overload.

14

Fig. hybrid HVDC circuit breaker

During normal operation the current will only flow through the bypass, and the current in the
main breaker is zero. When an HVDC fault occurs, the load commutation switch
immediately commutates the current to the main HVDC breaker and the fast disconnector
opens. With the mechanical switch in open position, the main HVDC breaker breaks the
current.

The mechanical switch isolates the load commutation switch from the primary voltage across
the main HVDC breaker during current breaking. Thus, the required voltage rating of the
load commutation switch is significantly reduced. A successful commutation of the line
current into the main HVDC breaker path requires a voltage rating of the load commutation
switch exceeding the on-state voltage of the main HVDC breaker, which is typically in the
kV range for a 320 kV HVDC breaker. This
result in typical on-state voltages of the load commutation switch is in the range of several
volts only. The transfer losses of the hybrid HVDC breaker concept are thus significantly
reduced to a percentage of the losses incurred by a pure semiconductor breaker, i.e. 0.01% of
the transmitted power.

The mechanical switch opens at zero current with low voltage stress, and can thus be realized
as a disconnector with a lightweight contact system. The fast disconnector will be exposed to
the maximum pole-to-pole voltage defined by the protective level of the arrester banks after
15

first being in open position while the main HVDC breaker opens. Thomson drives result in
fast opening times and compact disconnector design using SF6 as insulating media.

Proactive control of the hybrid HVDC breaker allows it to compensate for the time delay of
the fast disconnector, if the opening time of the disconnector is less than the time required for
selective protection. As shown in Figure, proactive current commutation is initiated by the
hybrid HVDC breaker`s built-in overcurrent protection as soon as the HVDC line current
exceeds a certain overcurrent level. The main HVDC breaker delays current breaking until a
trip signal of the selected protection is received or the faulty line current is close to the
maximum breaking current capability of the main HVDC breaker.

To extend the time before the self-protection function of the main HVDC breaker trips the
hybrid HVDC breaker, the main HVDC breaker may operate in current limitation mode prior
to current breaking. The main HVDC breaker controls the voltage drop across the HVDC
reactor to zero to prevent a further rise in the line current. Pulse mode operation of the main
HVDC breaker or sectionalizing the main HVDC breaker as shown in Fig.will allow
adapting the voltage across the main HVDC breaker to the instantaneous HVDC voltage
level of the HVDC grid. The maximum duration of the current limiting mode depends on the
energy dissipation capability of the arrester banks.

On-line supervision allowing maintenance on demand is achieved by scheduled current
transfer of the line current from the bypass into the main HVDC current breaker during
normal operation, without disturbing or interrupting the power transfer in the HVDC grid.
Fast backup protection similar to pure semiconductor breakers is possible for hybrid HVDC
breakers applied to HVDC switchyards. Due to the proactive mode, over-currents in the line
or superior switchyard protection will activate the current transfer from the bypass into the
main HVDC breaker or possible backup breakers prior to the trip signal of the backup
protection. In the case of a breaker failure, the backup breakers are activated almost
instantaneously, typically within less than 0.2 ms. This will avoid major disturbances in the
HVDC grid, and keep the required current-breaking capability of the backup breaker at

16

reasonable values. If not utilized for backup protection, the hybrid HVDC breakers
automatically return to normal operation mode after the fault is cleared.

3.3:-PROTOTYPE DESIGN OF THE HYBRID HVDC BREAKER:
The hybrid HVDC breaker is designed to achieve a current breaking capability of 9.0 kA in
an HVDC grid with rated voltage of 320 kV and rated HVDC transmission current of 2 kA.
The maximum current breaking capability is independent of the current rating and depends
on the design of the mainHVDC breaker only. The fast disconnector and main HVDC
breaker are designed for switching voltages exceeding 1.5 p.u. in consideration of fast
voltage transients during current breaking.

The main HVDC breaker consists of several HVDC breaker cells with individual arrester
banks limiting the maximum voltage across each cell to a specific level during current
breaking. Each HVDC breaker cell contains four HVDC breaker stacks as shown in Figure.
Two stacks are required to break the current in either current direction.

HVDC breaker cell
FIG. DESIGN OF 80KV MAIN HVDC BREAKER CELL

Each stack is composed of up to 20 series connected IGBT (insulated gate bipolar transistor)
HVDC breaker positions. Due to the large di/dt stress during current breaking, a mechanical
17

design with low stray inductance is required. Application of press pack IGBTs with 4.5 kV
voltage rating enables a compact stack design and ensures a stable short circuit failure mode
in case of individual component failure. Individual RCD snubbers across each IGBT module
ensure equal voltage distribution during current breaking. Optically powered gate units
enable operation of the IGBT HVDC breaker independent of current and voltage conditions
in the HVDC grid. A cooling system is not required for the IGBT stacks, since the main
HVDC breaker cells are not exposed to the line current during normal operation.

For the design of the load commutation switch, one IGBT HVDC breaker module for each
current direction is sufficient to fulfill the requirements of the voltage rating. Parallel
connection of IGBT modules increases the rated current of the hybrid HVDC breaker. Series
connected, redundant IGBT HVDC breaker modules improve the reliability of the load
commutation switch. A matrix of 3x3 IGBT positions for each current direction is chosen for
the present design. Since the load commutation switch is continuously exposed to the line
current, a cooling system is required. Besides water cooling, air-forced cooling can be
applied, due to relatively low losses in the range of several tens of kW only.

18

CHAPTER 4: TESTING OF HYBRID CIRCUIT
BERAKER
4.1:-TEST RESULTS MAIN BREAKER:
During the design of the hybrid HVDC breaker prototype, different tests were performed in
order to verify expected performance. The first test setup reported earlier focuses mainly on
the control of semiconductor devices and their current breaking capability. The second test
setup verifies both the voltage and current capability of one cell of the main HVDC breaker.
The ongoing extension of this test setup will focus on the overall performance of the hybrid
HVDC breaker. Due to big differences in voltage levels in the test setup, construction of the
test circuits is quite different but the test procedure is similar.

A scaled-down prototype of the main breaker cell with three series connected IGBT modules
and a common arrester bank was used to verify the current-breaking capability of 4.5 kV
StakPak IGBTs in the first test circuit as shown in Figure . A fourth IGBT module was
connected in opposite primarycurrent direction to verify the functionality of the incorporated
anti-parallel diode. Discharge of acapacitor bank by a thyristor switch, limited only by a
minor DC reactor, represents pole-to-ground faults in the HVDC grid. The HVDC voltage
level prior to the fault and after fault clearance is less critical, since the voltage stress across
the IGBT HVDC breaker positions during current breaking depends on the applied arrester
bank only.

Fig. DC breaker Component test Circuit

19

As shown in Figure, the maximum current breaking capability of the IGBT HVDC breaker
cell is determined by the saturation current of the applied IGBT modules rather than the safe
operation area (SOA) as is typical in voltage source converter applications. The series
connected HVDC breaker IGBT positions commutate the line current within 2 
s
(microseconds) into the RCD snubber circuits, which limits the rate of rise in voltage across
the positions to 300 V/ Zero voltage switching reduces the instantaneous switching losses
s.
and ensures equal voltage distribution independent of the tolerances in the switching
characteristics of the applied IGBT modules.

The line current commutates from the RCD snubbed circuit into the arrester path after the
common voltage across the IGBT HVDC breaker positions reaches the protective level of the
arrester bank. The IGBT HVDC breaker positions passed the stress tests for breaking
currents below 10 kA. For higher currents, the IGBT saturation current level is reached by
the internal current limitation in thebreaker, causing an immediate voltage drop across the
IGBT modules. During a purposely destructive test, the resulting internal heat dissipation
within the IGBT module destroys the encapsulated IGBT chips. Due to the use of press pack
IGBTs, a reliable short circuit without mechanical destruction of the failed IGBT module is
enabled. Since only one of the IGBT modules failed during the test, the fault can still be
cleared by the two other modules.

The nominal HVDC voltage per IGBT HVDC breaker cell is 80 kV. Due to the high voltage
level, the second test setup requires a significantly larger space. In Figure 7, the test circuit
for the hybrid HVDC breaker concept is shown. A ±150 kV HVDC switchyard supplies the
containerized test equipment to verify the functionality of the main IGBT HVDC breaker
represented by two series connected IGBT HVDC breaker stacks and a common arrester
bank. The desired HVDC voltage level is built up by charging the capacitor bank C1. The
reactor L1 is selected to give the expected current derivative (di/dt) during a short-circuit
fault. The short-circuit fault is initiated by the triggered spark gap Q5.

20

Fig. DC Breaker Test Circuit
Figure, shows a typical test result. A maximum breaking current of over 9 kA is verified. The
voltage across the HVDC breaker cell exceeds 120 kV during current commutation. The
breaking capability of one 80 kV HVDC breaker cell thus exceeds 1 GVA. Furthermore,
equal voltage distribution with a maximum voltage drop of 3.3 kV and a spread of less than
10 percent was only observed for the individual IGBT HVDC breaker positions in the HVDC
breaker cell.

21

4.2:-TEST RESULTS HYBRID HVDC BREAKER:
The main breaker test setup described in Section 5 and reported earlier was expanded to
verify the complete hybrid HVDC breaker concept. A second capacitor bank and large
reactors were installed to limit the rate of line current rise to typical HVDC grid values. The
ultra-fast disconnector and load commutation switch are included in the system
configuration.

Successful verification testing at device and component level has proven the performance of
the components. The complete hybrid HVDC breaker has now been verified in a
demonstrator setup at ABB facilities. The diagram in Figure 9 shows a breaking event with
peak current 9 kA and 2 ms delay time for opening the ultra-fast disconnector in the branch
parallel to the main breaker. The maximum rated fault current of 9 kA is the limit for the
existing generation of semiconductors. The next generation of semiconductor devices will
allow breaking performance of up to 16 kA. The purpose of the tests was to verify switching
performance of the power electronic parts, and the opening speed of the mechanical ultra-fast
disconnector. The test object consisted of one 80 Kv unidirectional main breaker cell, along
with the ultra-fast disconnector and load commutation switch. The higher voltage rating is
accomplished by connecting in series, several main breaker cells, but the switching stress per
cell is the same as in the demonstrator. This series connection approach is also used to test
conventional HVDC Light and HVDC Classic valves. Tests have not only been carried out
for normal breaking events, but also for situations with failed components in the breaker, in
order to verify reliable detection and safe operation in such cases.

22

Fig, Verification of the hybrid HVDC breaker system

23

CHAPTER 5: NEED OF HYBRID CIRCUIT BREAKER
AND SPECIFICATION
5.1:-NEEDS OF HYBRID CIRCUIT BREAKER
The ongoing research in the field of High Voltage Engineering focuses on the modeling of
Hybrid circuit breakers, which in the future have the potential to take over SF6 circuit
breakers. The vacuum interrupters have the ability to recover the dielectric strength across
the interrupting gap at the time of current zero. In case of vacuum arc mode, the dielectric
recovery is the fastest. Figure 1 indicates the comparison of dielectric strength recovery
speed between SF6 interrupter and vacuum interrupter when the gap is 6.35mm breaking
current 1600A, 180A vapor pressure. The rate of rise of vacuum recovery voltage is 20kV/us
which is faster than SF6. This type of CB has the following shortcomings:

Random dielectric breakdown across the open contacts of the CB can occur under
continuous voltage stress which can lead to energizing the system to be isolated. This
breakdown occurs for about one cycle of the system frequency.

The butt contacts of the CBs, may bounce or close. Due to the multiple make and
break operations occurring in the circuit, the voltage produced may reach above the
insulation level of the system and the equipment.

Vacuum interrupters have the tendency to chop the current as it reaches zero during
circuit interruption .High voltages comparable to the system voltage but less than the
insulation level are generated due to chopping .

The interrupting gap in SF6 CBs has high dielectric recovery capability along with
thermal recovery and high dielectrics withstand capability under continuous voltage
stress. This characteristic helps to prevent the random breakdown of the gap by
isolating the vacuum CB from the system. SF6 has wiping contacts of tulip and
24

bayonet type. SF6 arc resistance is higher than that of vacuum arc resistance. Thus in
the hybrid model SF6 CB bears the main voltage drop and works in conjunction with
vacuum CB to complete current interruption. These contacts make the circuit without
any bounce and thus no multiple system energisations will occur.

The hybrid circuit breaker has the following advantages over SF6 and vacuum CBs:
This type of breaker has the capability of switching short line faults at high voltage.
High operating force is not required and the size and the cost of the breaker reduces
Various standard design of this type are available which can be applied to free
standing breakers and compact substation breakers.
It has an excellent capability to deal with the steep-rising transient recovery voltage
(TRV).
A basic interrupting module can be formed which is rated at 145kV or more.

Fig. the comparison of dielectric recovery speed between
SF6 interrupter and vacuum interrupter

25

5.2:-SPECIFICATION
Table 3: Specification of hybrid circuit breaker
System Voltage

Interrupter Opening Time

Breaker Interrupt Time

325 Kv

240 s

340 s

125

130

230

50

85

185

7

65

165

26

CHAPTER 6: ABOUT OF THE INVENTION
6.1:-OBJECT OF THE INVENSION
It is an object of the present invention to present a hybrid circuit breaker which works on the
principle of keeping the voltage across a mechanical switch thereof sufficiently low to
prevent arcing between the contacts of the mechanical switch in connection to its switching
operation.

A hybrid circuit breaker which can be used in an electrical high-voltage network. This hybrid
circuit breaker has two series-connected arcing chambers, a first of which is filled with
sulfahexafluoride gas as a quenching and insulating medium, and a second of which is in the
form of a vacuum interrupter chamber. The second arcing chamber is surrounded by
sulfahexafluoride gas on the outside. The main contacts of the two arcing chambers are
operated simultaneously by a common drive via a simple lever transmission. Both arcing
chambers have a power current path, in each of which the erosion-resistant main contacts are
located and, in parallel with this, a rated current path, with this rated current path having only
a single interruption point. During disconnection, the rated current path is always interrupted
first of all, after which the current to be disconnected commutates onto the power current
path. The power current path then continues to carry the current until it is definitively
disconnected.

Simple lever transmissions such as these are comparatively difficult to match to the
movement profiles required in hybrid circuit breakers. Furthermore, the bearing points are
subject to mechanically very severe stresses, which results in the bearing points having a
complex and expensive design, as a result of which the hybrid circuit breaker price is
increased. If this configuration of the bearing points is dispensed with, then the time penalty
for the maintenance work which is then required more frequently restricts the availability of
the hybrid circuit breaker in a disadvantageous manner. Furthermore, the complexity for

27

installing the lever transmission in the interior of the hybrid circuit breaker is comparatively
great, owing to the restricted accessibility in this area.

6.2:-SUMMARY OF THE INVENTION
The invention, as it is characterized in the independent claims, achieves the object of
providing a hybrid circuit breaker having a transmission, which can be joined together easily
in the interior of the hybrid circuit breaker.

The hybrid circuit breaker has at least two series-connected arcing chambers, which are
operated by a common drive. These arcing chambers are preceded by a common
transmission. This transmission has at least two transmission parts, which are designed such
that they can be plugged together, with the first transmission part being firmly connected to
the at least one first arcing chamber, and the second transmission part being firmly connected
to the at least one second arcing chamber. The transmission has means which allow the
movements of the at least two arcing chambers to be technically sensibly matched to one
another and to be optimized with respect to the time sequence and switching speed thereof. It
has been found to be particularly advantageous for the transmission to be designed such that
it is self-locking both in the connected position and in the disconnected position since this
means that there is no need for any additional locking apparatus or catches. Furthermore, the
drive does not need to apply any particular holding forces in the two limit positions, so that a
simple and particularly low-cost drive can be used here.

The longitudinal axes of the two arcing chambers in one preferred embodiment of the hybrid
circuit breaker lie in one plane and are inclined at an angle α to one another, with the angle α
being less than 90°, and preferably being in the range between 68° and 800°. This
arrangement of the arcing chambers makes it possible to produce a hybrid circuit breaker
which has a comparatively short extent in the axial direction, so the space required for this
hybrid circuit breaker is particularly small.

The further refinements of the invention are the subject matter of the dependent claims.

28

The invention, its development and the advantages which can be achieved by it are explained
in more detail in the following text with reference to the drawing, which illustrates only one
possible embodiment approach.

CHAPTER 7: ADVANTAGES, DISADVANTAGES,
AND COST OF HYBRID BREAKER
7.1:-ADAVANTAGES
1. Arc-less interruption
2. Required fault current handling capability of the mechanical contacts can be
reduced.
3. Turn-on at lower fault current compared with the conventional hybrid breaker
4. Lower turn-off current.
5. The solid-state device must handle (dissipate) comparably lower energy.
6. Compact solution, the solid-state device is not as bulky as in the case of the
conventional hybrid breaker.
7. Lower temperature rise in the solid-state device due to lower peak current.
8. Current limiting ability
9. Can be used in both AC and DC current interruptions.
10. Lower varistor rating is required.
11. Overall turn-off process completes earlier.
12. Comparably lower commutation time possible.
13. Possible reduction of the conduction time of the solid-state breaker.
14. The connected network components don't need to be rated with respect to shorttime very high fault current-handling capability.

29

7.2:-DISADVANTAES
High cost
Complex design
Construction under process

7.3:-COST OF HYBRID CIRCUIT BREAKER

No.

Capacity rating

Prize(Rs)

1

Up to 11 kv

2000

2

Up to 121

11,000

3

Up to 500 kv

22,000

4

Up to 2000 A

50,000 (around)

30

CHAPTER 8: PHOTO OF HYBRID CIRCUIT
BREAKER

LIST OF DESIGNATIONS:
1 First longitudinal axis
2 Second longitudinal axis
3 Drive linkage
4 Bolt
5 Contact rod
6 Enclosure
7 Slot
8 Roller
9 Bolt
10 Rotation axis
11 Surface

31

12 Slotted guide disk
13 Bolt
14 Guide enclosure
15 Slot
16 Rotation axis
17, 18 Insulating enclosure
19 Bolt
20 Double lever
21 Bolt
22 Drive rod
23 Flange
24 Stop part
24a, 24b Shoulder
25 Collar
26 Cup spring pack
27 Step
28 Arrow
29 Transmission
30, 31, 32 Arrow
33 Curved surface
34 Planar surface
35 Guide tube
36 Slot
37 Collar
38 Slotted guide part
39 Slot
40 Guide slot
41 Bolt
42 Dashed line of action
42a, 42b Section
43 Holder
32

44 Union nut
a Angle
b Angle
R Radius of curvature

CONCLUSION
From the testing it is observed that the initial peak of the transient recovery voltage falls
across the vacuum interrupter and the later much higher peaks are taken by the SF6
interrupter. In this way both the SF6 interrupter and the vacuum interrupter assist each other.
The vacuum interrupter capability to withstand the steep rate of rise of recovery voltage
reduces the pressure of SF6 gas in SF6 interrupter. Hence it can be concluded that the
breaking capacity of the hybrid circuit breaker is more than that of the SF6 circuit breaker. In
the future, it can be seen as a great alternative of SF6 circuit breaker in high voltage
applications.

33

REFERANCE:
[1] E. Koldby, M. Hyttinen “Challenges on the Road to an Offshore HVDC Grid,” (Nordic
Wind Power Conference, Bornholm, Sept. 2009)
[2] Å. Ekström, H. Härtel, H.P. Lips, W. Schultz “Design and testing of an HVDC circuit
breaker,” (Cigré session 1976, paper 13-06)
[3] C.M. Franck “HVDC Circuit Breakers: A Review Identifying Future Research Needs,”
(IEEE Trans. on Power Delivery, vol. 26, pp. 998-1007, April 2011)
[4] J. Magnusson, O. Hammar, G. Engdahl “Modelling and Experimental Assessment of
Thomson Coil Actuator System for Ultra Fast Mechanical Switches for Commutation of
Load Currents,” (International Conference on New Actuators and Drive Systems, Bremen,
14-16 Juni 2010)
[5] G. Asplund “HVDC switch for current limitation in a HVDC transmission with voltage
source converters,” (European Patent EP0867998B1)
[6] S. Eicher, M. Rahimo, E. Tsyplakov, D. Schneider, A. Kopta, U. Schlapbach, E. Caroll
“4.5kV Press Pack IGBT Designed for Ruggedness and Reliability,” (IAS, Seattle, October
2004)
[7] M. Rahimo, A. Kopta, U. Schlapbach, J. Vobecky, R. Schnell, S. Klaka “The Bi-mode
Insulated Gate Transistor (BiGT) A potential technology for higher power applications,”
(Proc. ISPSD09, p. 283, 2009)
[8] J. Häfner, B. Jacobson, ” Proactive Hybrid HVDC Breakers - A key innovation for
reliable HVDC grids,” (Cigré Bologna, Paper 0264, 2011)

34

[9] J .J . V i t h a y a t h il , "HVdc Breaker and i t sApplication", Proceedings o fthe I n t e r
n a t i o n a l Symposium on HVdc Technology, Rio de Janeiro, B r a z i l , March 20-25,
1983
[10] B. Bachmann, G. Mauthe, E. Ruoss, H.P. Lips, J.W. Porter and J.J. V i t h a y a t h il ,
"Development o f a 500 kV A i r b l a s t HVdc C i r c u i t Breaker", IEEE Transactions on
Power Apparatus and Systems, Vol. 104, No. 9, September 1985, pp. 2460-2466.
[11] J.J. V i t h a y a t h il , A.L. Courts, W.G. Peterson, N.G. Hingorani, S . Nilson and J.W.
Porter, "HVdcC i r c u i t Breaker Development and F i e l d Tests", IEEE Transactions on
Power Apparatus and Systems, Vol. 104, No. 10, October 1985, pp, 2693-2705.
[12] A, Lee, P.G. Slade, K.H. Yoon, J. Porter and J. V i t h a y a t h i l , "The Development o
f a HVdc sF6 Breaker", IEEE Transactions on Power Apparatus and Systems, Vol. 104, No.
10, October 1985, pp. 2721-2729.
[13] D. Goldsworthy and J.J. V it h a y a t h il , "EMTP Model o f an HVdc Transmission
System", Proceedings of the IEEE Montech '86 Conference on HVdc Power Transmission,
September 29 - October 1, 1986, pp. 39-46.
[14] J.D. Cobine, "Gaseous Conductors, Theory and Engineering Applications", Dover Pub1
i c a t i o n s ,Inc. New York. pp. 344-348.
[15] K. Ragaller, A. Plessl, W. Hermann, W. Egli, "Calculation Methods f o r ,;he Arc
Quenching System o f Gas Circuit-Breakers , CIGRE Report 13-03, 1984.
[16] E. Bross, H. Schubert, "The DLF Range o fHigh Voltage A i r b l a s t C i r c u it
Breakers; Design Performance, Applications", Brown Boveri Review 65,1978
WEBSITE:
www.sumobrain.com/patents/wipo/Hybrid-circuit-breaker/WO2011044928.html
www.freepatentsonline.com/6727453.html
www.siemens.com/energy

35

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