FIELD OF THE INVENTION
The present invention relates to advanced Gas Interrupter device. In particular, it
relates to a Interrupter with dual motion contact system.
BACKGROUND OF THE INVENTION
When fault current is interrupted by a circuit breaker, an arc is struck between the
arcing contacts. The energy content of the arc depends on the current magnitude,
length of the arc and similar other parameters. As the temperature of the arc is
quite high it decomposes the insulating medium (gas) and materials exposed to
arc. Byproducts of the chemical reaction at elevated temperature also accumulate
in the vicinity destabilize insulation and shall be removed for sustaining the
dielectric properties of the inter-electrode gap for subsequent interruptions.
In conventional interrupters one of the two contacts is fixed, the moving contact is
driven by operating mechanism and an arc is struck on contact separation (Fig.l
(a)). At current-zero the arc is extinguished naturally exposing the developed
inter-electrode gap to system and transient recovery voltages. The gap reignites or
the arc is re-struck should the gap fail to withstand these voltages. For mechanical
constraints, limited inter-electrode gaps only can be generated in conventional

interrupters, promoting use of multiple breaks for EHV circuit breakers. Up to
245kV single-break circuit breaker designs are common, beyond this rating two or
more breaks are used in series to form a circuit breaker. The multiple breaks
require voltage equalizing devices like grading capacitors etc, affecting circuit
breaker reliability and cost.
Additionally the conventional interrupters use static field profiling electrodes
resulting in varying field intensities as the contacts separate. More clearly, when
shields are fixed the electrostatic field and voltage withstand capabilities of the
inter-electrode gap are limited. To overcome this constraint and to achieve desired
interrupter performance excess quantity of gas and higher differential pressures
are employed by designers.
Some Patented Invention related to this subject matter are US 20080257866A1,
US 4937406 and US 5739495.
US 20080257866A1 discloses invention relates to a circuit breaker (1) for high or
medium voltages, of the type having a drive bar (70) coupled to a drive member,
and a circuit-breaking chamber (2) facing it and having two contacts (3, 4), each
contact (3, 4) including a main contact (30, 40 respectively) and an arcing contact
(31, 41 respectively), with one of the two contacts (3) being fixed to a blast or
extinguishing nozzle (32). According to the invention, the second contact (4) and

the drive bar (70) are joined together by coupling means (6) in such a way that
they move together in translation in the same direction, the transmission means
(5) being disposed on the side (21) of the chamber (2) that is adjacent to the
drive bar (70), and are adapted to transmit the motion of the driven second
contact (4) to the first contact (3).
US 4937406 discloses an insulator-type gas circuit interrupter which comprises a
movable contact and a stationary contact for closing and separating a main circuit
and an insulator tube in which an arc-extinguishing chamber of a frustoconical
configuration is defined. The movable contact is disposed in the frustoconical arc-
extinguishing chamber at its smaller inner diameter side, and the stationary
contact is disposed in the frustoconical arc-extinguishing chamber at its larger
inner diameter side. An electrically insulating gas is sealed inside of the
frustoconical arc-extinguishing chamber.
US 5739495 discloses PCT No. PCT/DE95/00631 Sec. 371 Date Nov. 26, 1996 Sec.
102(e) Date Nov. 26, 1996 PCT Filed May 8, 1995 PCT Pub. No. W095/33274 PCT
Pub. Date Dec. 7, 1995A compressed-gas circuit breaker is provided with two
contacts arranged coaxially opposite one another, at least one of which can be
driven to move in the axial direction. The two contacts define in the interrupted
state a contact gap. The circuit breaker also has a nozzle, made of insulating

material, which is connected to the driven contact and which surrounds at least
part of the contact gap. The invention calls for a high-strength plastic tube
abutting coaxially against the outside of the insulating nozzle in order to prevent
the nozzle from expanding radially as a result of an increase in arc-extinguishing
gas pressure.
OBJECTS OF THE INVENTION
It is therefore the object of the present invention, to provide a improved
interrupter device with movable shield mechanism.
Another object of the present invention is to achieve lowest electrical stress levels
on second movable contact.
Another object of the present invention is to vent out arced gas during current
interruption.
Another object of the present invention is to accomplish pre-defined speed travel
characteristics of dynamic field controlled electrode through a novel trajectory
plate.
Another object of present invention is to limit very high pressures at the end of
stroke particularly for higher fault currents.

Yet another object of present invention is to provide protection of inter-electrode
gap (current transfer contact system) from hot/conducting gas contamination.
SUMMARY OF THE INVENTION
For successful interruption, the primary design requirements are: sufficient inter-
electrode gap; optimal dielectric properties of the gas and field uniformity in inter-
electrode gap. To address some of these requirements, a movable shield approach
has been innovated. Accordingly there is provided a interrupter device with a pin
surrounded by dynamic field controlled electrode, configured with relative motion
contact system. According to the present invention, a nozzle, is coupled to
trajectory plate through suitable couplers known as charging links which in turn
controls the movement of dynamic field controlled electrode. The present
invention further provides a interrupter device comprising a dual motion contact
system with three strategically coupled volumes to effectuate efficient gas flow
rate at interruption. The entire contact system being surrounded by a pressurized
gas, such as Sulphur Hexafluoride (SF6) or mixture of SF6 gas with other insulating
gases or equivalent gases. Further, profile of trajectory plate is designed in such a
way that the location of dynamic field electrode between the contacts can be
adjusted for maximum benefit, preventing stagnation/occupation of hot gas in the
inter-electrode gap of the contact system. Furthermore the present invention

propose and claim protection for a relative motion system in which pin operates on
its own during current interruption. The necessary energy required for this
movement is stored/ gained during preceding closing operation. It is the novelty of
the design that the pin is again under the control of primary driving system and
proper closing and opening of the contact system are ensured. The interrupter of
present invention additionally comprises features of reduction in operating
energies for the interrupter. Another embodiment of present invention is top dome
which is housing for trajectory plate and covers the dual motion mechanism,
trajectory plate and charging links, guide rods and provides uniform electric field.
Scissor lever arrangement is used in the present invention for coupling of nozzle to
the dynamic field controlled electrode for operation of dynamic field controlled
electrode. Present invention also provides an additional movement to the movable
contact due to arc energy generated by current interruption.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l - Conventional interrupters and with dual motion mechanism.
Fig.2 - Conventional interrupter housings.
Fig.3 - Conventional Insulating Nozzle
Fig.4 - First Movable contact Assembly
Fig.5 - Dynamic Field controlled electrode assembly.

Fig.6 - Scissor lever arrangement for coupling of nozzle to dynamic field controlled
electrode.
Fig.7 - Invented Insulated Nozzle Assembly.
Fig.8 - Invented Flexible coupling.
Fig.9 - Invented Circuit breaker with proposed design features.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
In general, to limit the voltage appearing across the contacts during interruption,
multiple breaks are preferred. The multiple break system is operated by same
drive which requires higher energy drive for its operation. To overcome this
problem, a dual motion contact system has been identified as an alternative
solution (Fig l.(b)). However, in all these systems, the second movable contact
i.e., other than primary moving contact takes sufficient portion of energy from the
operating mechanism. In some of the conventional breakers, such system have
relatively high energy requirements and are difficult to operate with low energy
mechanisms (ref: US 20080257866A1).
The electrostatic field, between movable and fixed contacts, is non-uniform for
various reasons like electrode profile and relative position of contacts. The field
intensification adversely affects voltage withstanding capabilities of the gas gap.

The availability of hot and conducting gas further complicates the situation
preventing successful interruption. In most of the interrupters, the arced gas after
leaving the nozzle may spill out into the contact system due to improper
channeling and this may lead to thermal failures. Beyond particular instant of time
during current interruption, minimum arcing time is decided by the effectiveness
with which arcing gas is being removed across inter-electrode gas gap and
uniformity of the electrostatic field between arcing contacts. To overcome this
problem, creepage length of nozzle is increased by different ways. Nevertheless
performance of the system is limited and none of the interrupters is utilized to full
capabilities. In some of the existing designs, the contact system is arranged in
metallic enclosure without arcing chamber assembly. This arrangement may cause
premature gas breakdowns during current interruption as the arced gas is not
contained and may directly make contact with metallic enclosure (refer Fig. 2(a)).
In conventional designs of insulated arcing chamber, when contacts are in open
condition, the electrostatic field across the insulator may be close to uniform. In
the absence of shields integrated to insulated arcing chamber the surface stress
cannot be controlled to the extent of requirement by means of arcing and current
carrying contact shields (refer US patent 4937406). However, during opening
operation (that is from closed condition to open condition) the arcing contacts are
out of their shields and the electrostatic stress across the contact system and

insulated arcing chamber increases enormously and may cause flashover at lower
recovery voltages (refer Fig. 2(b)).
The dielectric strength of inter-electrode gap not only depends on the effective
removal of arced gas but also on the density of fresh gas which occupies the arced
gas region. In conventional interrupters, once gas released from throat to
divergence zone, there is a possibility of mach number more than one due to
sudden expansion of gas (ref: US Patent No: 5739495). Because of increased
Mach number, gas pressure rise near throat region falls abruptly and sometimes
negative (refer Fig. 3). This in turn create low gas density region which become
critical for withstanding transient recovery voltages during current interruption.
In the present invention, the socket (01), made of a high conductivity and low
erosion material is held on a socket support or protection volume (02). The socket
is covered by a insulating shroud (03) made from low erosion insulating material.
The nozzle (05) is fixed to dynamic current carrying (CC) contact (04) and to the
socket contact assembly. The socket (01), insulating shroud (03) and current
carrying contact (04) are termed as the socket contact assembly. Fig.4 shows the
first movable contact assembly.
In interrupter fully open condition, the pin (06) is surrounded by a dynamic field
controlled electrode (07). The pin is located inside the dynamic field electrode and

the arrangement is again inside the stationary current carrying (CC) contact
assembly. The pin is dimensioned such that it promotes uniform electrostatic field
between the two contacts. The dimensions of the pin is also decided by the fault
current to be interrupted, pressure window required to interrupt all possible test
duties. The static current carrying contact assembly comprising static current
carrying (CC) contact (08) and static current carrying contact shield (09). The
arcing contact system and current carrying contact system are placed in insulated
arcing chamber assembly (10). The insulated arcing chamber assembly consists of
HT shield I (11) and HT shield II (12) (shielding electrodes) integrated to insulated
arcing chamber on either side. The insulated chamber is made of Aramid/Kevlar of
a combination of these fibers or equivalent material wound and impregnated with
epoxy resin in vacuum/pressure. The internal and external surfaces of insulated
chamber are resistant against arced SF6 gas. The profiles of HT shields are to
maintain uniform E-field between the arcing contact system and current carrying
contacts systems.
Invented device is constituted by three strategically coupled volumes. This aim of
the arrangement is to achieve efficient gas flow rate at interruption. The first
volume is the compression volume (13), where a piston-cylinder arrangement
allows storage of cold gas and its compression during interruption by movement of

a piston conventionally coupled to the operating mechanism/drive. Fresh gas is
collected and retained in this volume during closing operation. The second is an
expansion volume (15), where the available gas is directly exposed to arc during
contact separation/arcing. The third volume is an intermediate volume (14), where
stored gas is compressed by expansion volume (15) gas and where gas pressure
rises during arcing period due to both compression by expansion volume gas and
by mixing. There is an additional volume in series to compression volume called as
protection volume (02). At the end of stroke during opening operation this volume
helps to avoid in creating excessive gas pressures and will not load the
mechanism. One more objective of the breaker to provide back-up volume to the
compression volume (13) is to limit extremely high pressures during higher arcing
periods as pressure build-up in compression volume (13) is much higher in two
stage blast interruption. This protection volume (02) shall be optimized so that
interruption during no-load/light load conditions is not affected.
In interrupter open condition, the dynamic field controlled electrode (07) projects
out from the static current carrying contact shield (09) and the gas gap between
dynamic field controlled electrode (07) and dynamic current carrying contact (04)
decides the withstand voltage. Fig. 5 shows the dynamic field controlled electrode
system. The entire contact system is surrounded by SF6 gas at design density. The

socket is separated from the static current carrying contact shield by a design
distance, proportional to the system voltage and the SF6 gas density.
During opening operation, dynamic field controlled electrode (07) moves in
downward direction at a predefined instant of its operation depending on
anticipated minimum arcing time and the instant at which pin (06) contact crosses
the dynamic field controlled electrode (07). More clearly, at current-zero, the
voltage withstand capabilities between contacts is improved in the presence of
dynamic field controlled electrode (07). Socket assembly is coupled to dynamic
field controlled electrode (07) through nozzle (05) by means of a trajectory plate
(16). Profile of trajectory plate (16) is designed in such a way that the location of
dynamic field electrode between the contacts can be adjusted for maximum
benefit. The socket contact system, dynamic field controlled electrode (07) and the
coupling system are arranged such that at first current-zero the hot gas is vented
to main volume through the guided nozzle (05), preventing stagnation/occupation
of hot gas in the inter-electrode gap of the contact system. The trajectory plate
(16) is profiled in such a way that it decides the following parameters:
1. Speed characteristics of dynamic field controlled electrode (07).
2. Frictionless operation of dynamic field controlled electrode (07).

3. Gas gap between dynamic field controlled electrode (07) and dynamic
current carrying contact (04).
One embodiment of present invention is the nozzle (05) which is coupled to
trajectory plate (16) through suitable couplers known as charging links (17) which
in turn controls the movement of dynamic field controlled electrode (07). The
dynamic field electrode is coupled to trajectory plate (16) by means of guide rods
(18). The charging link (17) has a guiding slot whose configuration is designed by
the stroke of breaker and distance by which pin (06) travels. Fig. 5 shows the
interrupter with dynamic field electrode. The pin (06) is compressed against
damper (19) force and guided by current collector (20) when the CB is in open
condition. The pin (06) is connected to the charging link (17) through a
mechanical arrangement (21). This arrangement helps the pin (06) to engage
permanently with socket assembly and does not allow the pin (06) to move
independently. At a particular instant of closing operation, the mechanical
arrangement (21) comes into operation and the pin guided by damper (19) gets
compressed. This in turn results in movement of pin (06) and storage of spring
energy in the damper (19). Once breaker is closed, the toggle between mechanical
arrangement (21) and charging link (17) ensures pin location; the toggle is
reactivated by open command of the interrupter. During opening operation, the

pin (06) is initially held by the socket, friction between pin (06) and socket (01).
The pin (06) on release from socket (01) moves at a speed decided by energy
stored, weight of the pin (06) and friction offered by current collector (20). As the
travel of the pin (06) in controlled, it acts as a static contact beyond this travel.
The distance to which pin (06) is displaced can be adjusted by modifying the
design parameters of mechanical arrangement (21). Once opening operation is
completed, the pin is coupled to the charging link through mechanical
arrangement in such a way that it cannot operate on its own. Fig. 5 shows the
invented interrupter with a relative motion contact system approach. The
mechanical arrangement (21) consists of a rotary shaft (21A) supported at either
end by bearing housings through load bearings. Suitable levers (21B) are used to
couple rotary shaft (21A) and movable arcing contact (pin) (06). The dimensions
of lever (21B) and angle of rotation are decided by stroke and speed of the second
movable contact (06). The speed of second movable contact (06) is designed
based on dielectric recovery requirements of the interrupter at minimum arcing
time. The trajectory of dynamic field controlled electrode (07) is designed based
on position with respect to time instant after contact separation.
The present invention propose and claim a relative motion system in which pin
(06) operates on its own during current interruption. The necessary energy

required for this movement is stored/ gained during preceding closing operation. It
is the novelty of the design that the pin (06) is again under the control of primary
driving system and proper closing and opening of the contact system are ensured.
The interrupter invented additionally features reduction in operating energies for
the interrupter.
The main drive is coupled to dynamic field controlled electrode (07) through
insulating nozzle (05), trajectory plate (16) and scissor levers (22). The trajectory
plate (16) is fixed to the top dome (23) of the assembly. One more objective of
the patent is design of top dome (23) which is housing for trajectory plate (16)
and covers the dual motion mechanism, trajectory plate (16) and charging links
(17), guide rods (18) and provides uniform electric field. Top dome (23) is in
spherical shape made from thin sheet and a member (23A) is integrated to it to
couple to trajectory plate (16). Top dome (23) has provision to couple
mechanically to dual motion mechanism housing (24), which holds the mechanical
arrangement (21). The guide rods (18) are coupled to moving element (25) which
in turn coupled to trajectory plate (16). The charging links (17) from nozzle (05)
are coupled to the trajectory plate (16) through scissor lever arrangement (26).
The scissor lever arrangement (26) consists of two levers from each charging link
(17). The set of levers (22) from each charging link (17) are connected to other

set of levers through a moving element (25). Suitable guiding element and spacers
are provided between levers to ensure smooth operation of dynamic field
controlled electrode (07).
One more objective of the present invention is to guide arced gas venting out
during current interruption. The proposed model prevents hot/arced gas
contamination of inter-electrode gap during current interruption. For this purpose,
a nozzle holder (27) with suitable inner guide ring (28) is kept inside a metal tube
(29). The metal tube is integrated with dynamic field controlled electrode (07).
The dynamic field controlled electrode (07) will be guided by outer guide ring (30)
located in static current carrying (CC) contact (08). The arced gas venting out
from nozzle will not be allowed to leak into the contact system because of the
inner and outer guide rings (28, 30). Fig. 6 shows the scissor lever arrangement is
used in the present invention for coupling of nozzle to the dynamic field controlled
electrode.
The second terminal of the nozzle (05) is coupled to the pin (06) through a
mechanical arrangement (21) and an energy storage device. The second terminal
of the nozzle (05) is at a fixed potential rather than at floating potential as in the
some of the conventional systems. The nozzle (05) design is optimized by
considering mechanical, thermal, electrical and flow parameters. The nozzle (05)

shall withstand to mechanical forces offered by drive and gas pressure rise during
arcing phenomena. The design shall be suitable for uniform electrostatic field
across nozzle surface and effective mass (pressurized gas) transportation. Total
profile of proposed nozzle (05) has been divided into five zones.
These zones are defined as Converging zone CZ1 (31), straight zone or throat
region SZ1 (32), First diverging zone DZ1 (33), Second diverging zone DZ2 (34)
and third diverging DZ3 (35). Each zone has its significance in the gas flow and
decides the performance of circuit breaker during current interruption. CZ1 (31) is
a converging zone connects intermediate volume (12) and throat region. SZ1 (32)
is a straight zone or throat zone, connects converging to diverging portion of the
nozzle. The distance to which it occupies depends primarily on speed of the
moving contact system. The diameter of the throat depends on fault current to be
interrupted. If the throat zone (32) is less than required input pressure from
thermal volume may not be sufficient to develop necessary density for the gas
across the contact system. The diverging angle of the diverging zones (DZ1, DZ2
and DZ3) is different from each other. The angle of divergence of DZ1 (33) is
about 40 to 60 degrees. The distance to which this zone occupies depend on the
diameter of throat/fixed contact/ fixed movable contact. This profile decides the
density of gas in the SZ1 zone (32) and DZ1 zone (33) during current zero period.

In other words, DZ1 profile decides with standability of breaker for transient
recovery voltage at current zero. If the profile allows sudden expansion, there is a
possibility of Mach number more than 1 (one) and negative pressure prevails in
the SZ1 zone (32) and in divergence zone DZ1 (33). High Mach number in this
zone results to low gas density area and reduces the dielectric strength of the gas
across inter-electrode system (across arcing contacts / inner surface of nozzle).
The divergence angle of DZ2 (34) is about 2 to 5 degrees. The distance to which
this zone occupies depends on speed of the moving contact / fixed contact (dual
motion) and arcing times of the breaker. Gas flow rate across arcing channel shall
be sufficient enough to quench the arc around current zero. If the angle of the
DZ2 zone (34) is less, contact system has to travel more distance to get sufficient
gas flow and may increase arcing time. The divergence angle of DZ3 (35) zone is
about 40 degrees or more. The distance to which it occupies depends on
difference between time to establish isolation between arcing contacts (Moving
contact and movable fixed contact) and maximum arcing time. This zone helps to
guide arced gas to vent out effectively without spilling out into the region of
current carrying contact system. Figure 7 shows the invented nozzle.
One more objective of the design is to increase the operating speed of second
movable contact (06) using arcing energy. The nozzle design is made in such a

way that during nozzle clogging, the pressure in expansion volume (15) helps to
increase the opening speed of second movable contact (06). The gas pressure in
expansion volume (15) increases with increase of fault current. Under light load
conditions, only spring (19) energy will be used to open the second movable
contact (06). The time over which nozzle clogging takes place decides the pressure
build-up and speed of the second movable contact (06).
One more objective of present patent is to provide adjustable coupling (36) from
breaker pole to terminals of breaker (37) as it requires high quality manufacturing
to achieve linear and angular accuracy. The proposed coupling element (36) is
adjustable in both directions and transfers current effectively from/to the circuit
breaker pole. This is achieved by using adjustable spacers (38) on either side of
coupling element. Fig. 8 shows the flexible coupling element. This coupling is
effective for higher fault currents of tens of kilo amperes and higher rated currents
of thousands of amperes. This coupling element (36) consists of cylindrical
member of rotatable type with current transfer contacts (39). This coupling
transfers current from dual motion mechanism housing (24) to circuit breaker
terminal (37). The mechanism housing transfers current from static current
carrying (CC) contact (08) to coupling element (36). The breaker terminal (37)
transfers current to the next GIS module through support insulator (40). The

circuit breaker pole is located in a grounded metallic enclosure (41). Fig. 9 shows
the invented interrupter with a relative motion contact system and dynamic field
controlled electrode for gas interrupter, in closed condition.

WE CLAIM
1. An interrupter device to improve interrupting performance for high voltage
circuit breakers comprising:
- a first movable contact assembly wherein comprises a socket (1)
encapsulated by a insulating shroud (3), the said socket being held on a
support or protection volume (2) and a dynamic current carrying contact
(CC) assembly ( 4), wherein the socket contact assembly (1, 2, 3) and
dynamic contact (4) being coupled by a nozzle (5);
- a second movable contact assembly (6), disposed within a dynamic field
controlled electrode (7) and the said arrangement is positioned inside a
static current carrying contact assembly which includes a static current
carrying contact (8) and static current carrying contact shield (9);
- three coherent volumes to effectuate steady gas flow rate at the time of
interruption, wherein the third volume (15) is coupled in series with the
said protection volume (2);
- wherein the main drive is coupled to dynamic field controlled electrode
to effectuate relative motion contact system.

2. The device as claimed in claim 1, wherein the said socket assembly and
dynamic field controlled electrode (7) are coupled by means of a trajectory
plate (16).
3. The device as claimed in claim 2, wherein the trajectory plates (16) are
coupled to nozzle (5) by means of scissor lever arrangement (26).
4. A dual motion contact system positioned in the interrupter device
comprises:

- a first movable contact assembly which further comprises of a socket
being protected by a insulating shroud and a dynamic current carrying
contacts, wherein the socket is disposed on a support means;
- a second movable contact disposed inside the dynamic field electrode
being positioned within a static CC contact assembly wherein the second
movable contact is under the control of primary driving system, at least
one of the said movable contacts operates independently relative to the
other, during current interruption.0

ABSTRACT

An interrupter device to improve interrupting performance for high voltage circuit
breakers comprising a first movable contact assembly wherein comprises a socket
(1) encapsulated by a insulating shroud (3); the said socket being held on a
support or protection volume (2) and a dynamic current carrying contact assembly
(4) wherein the socket contact assembly (1, 2, 3) and dynamic contact (4) being
coupled by a nozzle (5) a second movable contact assembly (6), disposed within a
dynamic field controlled electrode (7) and the said arrangement is positioned
inside a static current carrying contact assembly wherein comprises a static current
carrying contact (8) and static CC contact shield (9) three coherent volumes to
effectuate steady wherein the gas flow rate at the time of interruption third
volume (14) is coupled in series with the said protection volume (2) wherein the
main drive is coupled to dynamic field controlled electrode to effectuate relative
motion contact system.