A HORIZONTALLY MOUNTED GAS CIRCUIT BREAKER FOR HYBRID GAS
INSULATED SWITCH GEAR
TECHNICAL FIELD
[001] The present disclosure, in general, relates to gas circuit breaker for
hybrid gas insulated switchgear and specifically relates to horizontally
mounted gas circuit breaker for hybrid gas insulated switchgear that is
compact and can be safely operated in confined spaces.
BACKGROUND
[002] Background description includes information that may be useful in
understanding the present invention. It is not an admission that any of the
information provided herein is prior art or relevant to the presently claimed
invention, or that any publication specifically or implicitly referenced is prior
art.
[001] At present, the demand for electrical power is growing rapidly, and
this can be fulfilled by the power generating substations. There are different
types of power generating substations like thermal, atomic, and hydroelectric. Based on the availability of different resources, substations are
building at different locations, but these locations may be closer to load
centers. The actual power utilization can be done by the load center. So it
is essential to transmit the power from the substation to load center
locations.
[002] In general, It is very much required to establish an electrical
substation at load center. Since, establishing a substation at load center is
quite economical and profitable in many aspects. As it reduces length of
feeders and due to short length feeders, the quality of voltage regulation
improves. But the main obstruction of establishing a substation at load
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center is space. Generally main load center of any place is situated at very
congested place where, sufficient land for establishing conventional
electrical substation is very hardly available.
[003] This problem can be solved by using gas insulated switchgear
technology. In this type of switchgear, all the necessary components of
switchgear can be assembled in very limited space. GIS is a kind of metal
enclosed switchgear.
[004] That means, all the equipments of the electrical switchgear are
enclosed by gas tight metal enclosure and SF6 gas is used as insulation
between live parts of the equipments and earthed metal enclosure. This
type of switchgear, means, and gas insulated switchgear is available from
12 KV systems to 800 KV system. For establishing electrical substation in
very limited place this type of SF6 insulated electrical switchgear plays the
major role.
[005] The substation, assembled by gas insulated switchgear, is popularly
known as gas insulated metal enclosed substation (GIMES). GIMES
technology is not very recent invention, it is successfully running for over
thirty years.
[006] In gas insulated medium voltage switchgear, a vacuum technology
is used as interrupting purpose and SF6 gas is used as insulation material.
Although for both interruption and insulation, SF6 gas is used in many
medium voltage GIS systems. But for such equipment’s rated SF6 gas
pressures are different for interruption and insulation. SF6 gas pressure for
insulating purpose is generally kept below 2.5 bar whereas SF6 gas
pressure for interrupting purpose is ranged from 5 bar to 7 bar.
[007] As vacuum technology is not available for high voltage, so for GIS or
gas insulated switchgear system above 72.5 KV, only SF6 is used both for
interruption medium and insulation.
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[008] However, a hybrid gas insulated switchgear is one that combines the
components of traditional air-insulated switchgear (AIS) and SF6 gasinsulated switchgear (GIS) technologies. It is characterized by a compact
and modular design, which encompasses several different functions in one
module.
[009] The Gas-insulated switchgear design can be done using different
components like circuit breakers, bus bars, disconnectors or
isolators, transformers like voltage and current, earth switches, lightning
arresters, and surge arrestors.
[010] The circuit breaker is an electrical safety device designed to protect
an electrical circuit from damage caused by an overcurrent or short circuit.
Its basic function is to interrupt current flow to protect equipment and to
prevent the risk of fire. Unlike a fuse, which operates once and then must
be replaced, a circuit breaker can be reset (either manually or automatically)
to resume normal operation.
[011] Circuit breakers are made in varying sizes, from small devices that
protect low-current circuits or individual household appliances, to large
switchgear designed to protect high voltage circuits feeding an entire city.
The generic function of a circuit breaker, or fuse, as an automatic means of
removing power from a faulty system, is often abbreviated as OCPD (Over
Current Protection Device).
[012] In Sulphur Hexafluoride or SF6 Circuit Breaker, Sulphur hexafluoride
(SF6) gas is used as an insulating and arc quenching medium. SF6 gas has
many superior properties which makes it perfect for arc quenching. Sulphur
Hexafluoride or SF6 Circuit Breaker is most popular and widely used
breaker. This type of breaker is mostly used for EHV systems like 220 kV,
400 kV and 765 kV.
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[013] Like other circuit breaker viz. Vacuum Circuit Breaker, Air Blast
Circuit Breaker etc., SF6 Circuit Breaker has fixed contact as well as moving
contact. Theses fixed and moving contacts are known as MAIN CONTACT.
There exists one another contact which is known as ARCING CONTACT.
Arcing Contact is part of fixed contact. Basically, Arcing contacts are only
designed to withstand arcing. It is not designed for carrying load current. In
spite, main contacts are designed to carry load current and not the arcing.
[014] Therefore, it can be said that, while closing of SF6 circuit breaker,
first arcing Contact will close. Thereafter main contact will close. Similarly,
while opening, first main contact will open and then arcing contact will
open. Notice here that, during opening operation of SF6 Circuit Breaker, the
order of opening main and arcing contact is revered as that in closing
operation. This is because, while opening if the main contact opens first,
there will not be any arcing as the current is getting path through the arcing
contact. But if the arcing contact open first then during opening of main
contact there will be arcing and as discussed main contacts are not meant
to withstand arcing.
[015] Apart from Fixed contact and moving contacts, SF6 Circuit Breaker
has following main components:
 Interrupter
 Insulating Nozzle
 SF6 Gas Chamber
[016] Types of SF6 Circuit Breaker
As discussed, in 220 kV, 400 kV and 765 kV applications, the SF6 gas pressure is
maintained at 6.5 bar. Even though voltage level is increasing, same pressure of
SF6 i.e. 6.5 bar is used for 220, 400 and 765 kV applications. Actually as we go up
at higher voltage level, the number of contacts increases in SF6 circuit Breaker.
Based on this philosophy, SF6 circuit breaker can be classified into following types:
 Single Breaker Circuit Breaker
 Double Break Circuit Breaker
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 Multi Break Circuit Breaker
[017] Single Break SF6 Circuit Breaker
In Single Break Circuit Breaker, only one moving and fixed contacts are
present. This means that, there will only be one interrupter unit in such
breaker. Single break SF6 circuit breaker is used for 220 kV applications.
[018] Double Break SF6 Circuit Breaker
In such type of breaker, there are two set of moving and fixed contacts
connected in series. Therefore, to enclose two set of contacts, there must
be two interrupt unit in series. This type of breaker is used in 400 kV
applications. In double break circuit breaker, grading capacitors are used to
equalize the voltage distribution across each contact. Thus for 400 kV
application, the voltage across each contact will be 200 kV. Therefore it is
logical to use SF6 gas at a pressure same as used in 200 kV application.
[019] Multi Break SF6 Circuit Breaker
In multi break circuit break, more than two set of fixed and moving contacts
are used. Such type of breaker is used in 765 kV applications.
[020] In case of single break gas circuit breakers, vertically mounted
arrangements are generally employed. However, for multiple break gas
circuit breakers, horizontally mounted arrangements are preferred. As the
vertically mounted arrangements can only be installed inside the larger gas
insulated switchgear (GIS). Further, they are also not effective for hybrid
GIS installations as gas-to-air bushings have to be installed according to
the circuit breaker height.
[021] In view of above, horizontally mounted arrangement are becoming
prominent even for single break type gas circuit breakers. This type of
breakers is called as horizontally mounted gas circuit breakers. It is also
important to limit the dimensions of breaker to establish the GIS or HGIS as
compact as possible. In addition, the arrangement of circuit breaker pole is
more critical in horizontal type breakers as suitable support insulators need
to be employed to ensure reliable operation during service.
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[022] To address these issues, there is a need of horizontally oriented gas
circuit breaker having support insulators that can be efficiently used in
hybrid gas insulated switchgear (HGIS) applications. In addition, there is
also a need of a spherical cover to create necessary insulation and to limit
mechanical stresses against high pressures encountered during severe
fault conditions.
OBJECTS OF THE DISCLOSURE
[023] Some of the objects of the present disclosure, which at least one
embodiment herein satisfy, are listed herein below.
[024] It is a general or primary object of the present invention to propose
horizontally mounted gas circuit breaker with dual motion contact system.
[025] It is another object of the present invention to propose horizontally
mounted gas circuit breaker with dual motion contact system and dynamic
field electrode.
[026] It is yet another object of the present invention to propose horizontally
mounted gas circuit breaker with pole assembly supported by epoxy
insulators and FRP insulator housings.
[027] It is further another object of the present invention to propose
horizontally mounted gas circuit breaker with horizontal support from
insulating tube on either end of pole assembly.
[028] It is yet another object of the present invention to propose horizontally
mounted gas circuit breaker pole assembly supported by four to five
insulators depending type of configuration
[029] It is yet further object of the present invention to propose horizontally
mounted gas circuit breaker pole assembly supported by a singular support
insulator by using spherical dome as high voltage shield.
[030] It is another object of the present invention to propose horizontally
mounted gas circuit breaker pole assembly supported by the support
insulator which is plugged into spherical disc cover assembly of circuit
breaker enclosure.
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[031] It is another object of the present invention to propose the
horizontally mounted gas circuit breaker with minimum number of cone or
disc epoxy insulators for supporting circuit breaker pole assembly.
[032] It is another object of the present invention to propose the support
insulator to guide spherical dome of left hand pole with lowest possible
discharge / radial distance.
[033] It is another object of the present invention to propose the support
insulator without additional high voltage or grounded metallic shields.
[034] It is another object of the present invention to propose the support
insulator such that the mechanical strength of insulator is ensured by using
appropriate gluing techniques.
[035] It is another object of the present invention to propose a spherical
dish cover to guide pole assembly of horizontally mounted gas circuit
breaker.
[036] It is another object of the present invention to propose a spherical
cover to create necessary insulation and to limit mechanical stresses
against high pressures encountered during severe fault conditions.
[037] These and other objects and advantages will become more apparent
when reference is made to the following description and accompanying
drawings
SUMMARY
[038] This summary is provided to introduce concepts related to a
horizontally oriented gas circuit breaker for hybrid gas insulated switchgear,
which helps in optimizing bay width in gas-insulated switchgear (GIS) bay.
The concepts are further described below in the detailed description. This
summary is not intended to identify key features or essential features of the
claimed subject matter, nor is it intended to be used to limit the scope of the
claimed subject matter.
[039] In accordance with an embodiment, the present disclosure proposes
a horizontally mounted gas circuit breaker for hybrid gas insulated switch
gear comprises a left hand side pole shell having three ports, wherein a first
port and third port being connected to an epoxy support insulator, a second
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port being connected to a first FRP insulator; and a right hand side pole
shell having three ports, wherein a first port being connected with the epoxy
support insulator ,a second port being connected to second FRP insulator
through support plate and mechanism housing , a third port being connected
to a spherical dish with moisture absorbents ; wherein the left hand side and
the right hand side pole shell includes a four-way connector and being
joined by a standard tube .
[040] In an aspect, the epoxy support insulator is supported by a spherical
Cover-II, an HT terminal, an HT shield and a terminal shield.
[041] In an aspect, the spherical cover includes a spherical profile having
radius (R) that needs to be 80 to 100 % of Inner diameter (D) of the dish
cover.
[042] In an aspect, the tube of the FRP insulator is made of a material
including FRP or Kevlar.
[043] In an aspect, a first end of the tube of the FRP insulator is connected
to a ground terminal.
[044] In an aspect,a second end of the tube of the FRP insulator is
connected to a high voltage terminal.
[045] In an aspect, the high voltage terminal and tube of FRP insulator is
fixed through gluing and the grounded terminal and tube of FRP insulator
(03) is also fixed through gluing.
[046] In an aspect, the high voltage terminal and grounded terminal of the
tube of the FRP insulator are fixed, that lowest possible radial /discharge
distance, “G” can be achieved and sufficient gluing length of these terminals
can be ensured.
[047] Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed
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description of preferred embodiments, along with the accompanying
drawing figures in which numerals represent like components.
BRIEF DESCRIPTION OF THE DRAWINGS
[048] The illustrated embodiments of the subject matter will be best
understood by reference to the drawings, wherein like parts are designated
by like numerals throughout. The following description is intended only by
way of example, and simply illustrates certain selected embodiments of
devices, systems, and methods that are consistent with the subject matter
as claimed herein, wherein:
[049] Figure 1 illustrates the left hand side shell of the horizontally
mounted gas circuit breaker enclosure [01] in accordance with a prior art.
[050] Figure 2 illustrates a Right hand side pole assembly of the
horizontally mounted proposed gas circuit breaker in accordance with the
prior art.
[051] Figure 3 illustrates Left hand and right hand pole assemblies in
combination located in horizontally mounted gas circuit breaker enclosure
in accordance with the prior art.
[052] Figure 4 illustrates a block diagram of the horizontally mounted gas
circuit breaker enclosure having symmetrical structure in accordance with a
present invention.
[053] Figure. 5 illustrates the proposed horizontally mounted gas circuit
breaker in accordance with an embodiment of the present invention.
[054] Figure. 6 illustrates the insulator assembly in accordance with an
embodiment of the present invention.
[055] Figure.7 illustrates the FRP insulator with spherical dome and
spherical cover in accordance with an embodiment of the present invention
[056] Figure.8 illustrates the structure of the spherical cover in accordance
with an embodiment of the present invention.
[057] Figure. 9 shows the double bus Hybrid gas insulated switchgear bay
with horizontally mounted gas circuit breaker in accordance with an
embodiment of the present invention.
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DETAILED DESCRIPTION
[058] The following is a detailed description of embodiments of the
disclosure depicted in the accompanying drawings. The embodiments are
in such detail as to clearly communicate the disclosure. However, the
amount of detail offered is not intended to limit the anticipated variations of
embodiments; on the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the spirit and scope of the present
disclosure as defined by the appended claims.
[059] As used in the description herein and throughout the claims that
follow, the meaning of “a,” “an,” and “the” includes plural reference unless
the context clearly dictates otherwise. Also, as used in the description
herein, the meaning of “in” includes “in” and “on” unless the context clearly
dictates otherwise.
[060] Figure 1 illustrates the left hand side shell of the horizontally
mounted gas circuit breaker enclosure [01] in accordance with a prior art.
[061] The left hand side shell [01A] consists of dynamic field-controlled
electrode [19], movable fixed contact [20], charging links [21], trajectory
plate [22], mechanical arrangement [23], damper [24], current collector [25],
guide rods [26], mechanism housing [27], spherical dome [28], spherical
dome member [28A], member [29], scissor lever arrangement [30] and
moving element [31].
[062] The socket assembly [09] is coupled to dynamic field-controlled
electrode [19] through nozzle [10] as shown in FIG.3 by means of a
trajectory plate [22]. The profile of trajectory plate [22] is designed in such a
way that the location of dynamic field- controlled electrode [19] between the
contacts can be adjusted for maximum benefit. The socket contact system
[09], dynamic field controlled electrode [19] and the coupling system are
arranged such that during the first current-zero condition, the hot gas is
vented to moving element [31] through the guided nozzle [10], preventing
stagnation/ occupation of hot gas in the inter-electrode gap of the contact
system.
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[063] In addition, the trajectory plate [22] is profiled in such a way that it
decides the following parameters: Speed characteristics of dynamic field
controlled electrode [19]. Frictionless operation of dynamic field controlled
electrode [19], and Gas gap between dynamic field controlled electrode [19]
and dynamic current carrying contact [09D].
[064] The nozzle [10] is coupled to trajectory plate [22] through suitable
couplers known as charging links [21] which in turn controls the movement
of dynamic field controlled electrode [19]. The dynamic field electrode is
coupled to trajectory plate [22] by means of guide rods [26]. The charging
link [21] has a guiding slot whose configuration is designed by the stroke of
breaker and distance by which pin / movable fixed contact [20] travels.
[065] The pin / movable fixed contact [20] is compressed against damper
[24] force and guided by current collector [25] when the circuit breaker is in
open condition. The pin / movable fixed contact [20] is connected to the
charging link [21] through a mechanical arrangement [23]. This
arrangement helps the pin / movable fixed contact [20] to engage
permanently with socket assembly and does not allow the pin / movable
fixed contact [20] to move independently.
[066] During opening operation, dynamic field controlled electrode [19]
moves to right side direction at a predefined instant of its operation
depending on anticipated minimum arcing time and the instant at which pin
/ movable fixed contact [20] crosses the dynamic field controlled electrode
[19]. More clearly, at current-zero, the voltage withstand capabilities
between contacts is improved in the presence of dynamic field-controlled
electrode [19].
[067] In addition, during opening operation, the pin / movable fixed contact
[20] is initially held by the socket [09], friction between pin / movable fixed
contact [20] and socket [09]. The pin / movable fixed contact [20] on release
from socket [09] moves at a speed decided by energy stored, weight of the
pin / movable fixed contact [20] and friction offered by current collector [25].
As the travel of the pin / movable fixed contact [20] is controlled, it acts as
a static contact beyond this travel. The distance to which movable fixed
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contact [20] is displaced can be adjusted by modifying the design
parameters of mechanical arrangement [23].
[068] Once opening operation is completed, the pin [20] is coupled to the
charging link [21] through mechanical arrangement [23] in such a way that
it cannot operate on its own. The mechanical arrangement [23] consists of
a rotary shaft supported at either end by bearing housings through load
bearings. Suitable levers are used to couple rotary shaft and movable arcing
contact (pin) [20]. The dimensions of lever and angle of rotation are decided
by stroke and speed of the movable fixed contact [20]. The speed of
movable fixed contact [20] is designed based on dielectric recovery
requirements of the interrupter at minimum arcing time. The trajectory of
dynamic field-controlled electrode [19] is designed based on position with
respect to time instant after contact separation.
[069] During closing operation, the mechanical arrangement [23] comes
into operation and the pin / movable fixed contact [20] guided by damper
[24] gets compressed. This in turn results in movement of the pin / movable
fixed contact [20] and storage of spring energy in the damper [16]. Once
breaker is closed, the toggle between mechanical arrangement [23] and
charging link [21] ensures pin / movable fixed contact [20] location; the
toggle is reactivated by open command of the interrupter.
[070] The relative motion system in which pin [20] operates on its own
during current interruption. The necessary energy required for this
movement is stored / gained during preceding closing operation. It is one of
the feature of the configuration that the pin [20] is again under the control of
primary system and proper closing and opening of the contact system are
ensured. The interrupter additionally features reduction in operating
energies for the interrupter.
[071] Moreover, the main drive is coupled to dynamic field-controlled
electrode [19] through insulating nozzle [10], trajectory plate [22] and
scissor levers [30]. The trajectory plate [22] is fixed to the spherical dome
[28] of the assembly.
[072] A spherical dome [28] is also exists in the configuration which is
used for housing of trajectory plate [22] and provides uniform electric field.
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The spherical dome [28] is in spherical shape made from thin sheet and a
member [29] is integrated to it to couple to trajectory plate [22]. The
spherical dome [28] has provision to couple mechanically to dual motion
mechanism housing [27], which holds the mechanical arrangement [23].
The guide rods [26] are coupled to moving element [31] which in turn
coupled to trajectory plate [22]. The charging links [21] from nozzle [10] are
coupled to the trajectory plate [22] through scissor lever arrangement [30].
The scissor lever arrangement [30] consists of two levers from each
charging link [21]. The set of levers [30] from each charging link [21] are
connected to other set of levers [30] through a moving element [31]. Suitable
guiding element and spacers are also provided between levers to ensure
smooth operation of dynamic field-controlled electrode [19].
[073] Figure 2 illustrates a Right hand side pole assembly of the
horizontally mounted proposed gas circuit breaker in accordance with the
prior art.
[074] The right hand pole assembly consists of socket assembly [09],
nozzle [10], expansion volume [11], compression volume [12], piston [13],
puffer base [14], support housing [33], current transfer flange [15],
integrated to pull tube [16] assembly through insulated operating rod [17] to
the main drive [18]. The pull tube [16] is connected to the socket assembly
[09] and provides a path for disposal of arced gas through the socket
assembly [09]. The socket [09A], made of a high conductivity and low
erosion material is held on a socket support or protection volume [09B]. The
socket is covered by an insulating shroud [09C] made from low erosion
insulating material. The nozzle [10] is fixed to dynamic current carrying (CC)
contact [09D] of the socket contact assembly. The static current carrying
contact assembly comprising static current carrying (CC) contact [34] and
static current carrying contact shield [35]. The arcing contact system and
current carrying contact system are placed in insulated arcing chamber [36].
[075] The insulated chamber is made of Aramid / Kevlar or a combination
of these fibers or equivalent material wound and impregnated with epoxy
resin in vacuum/ pressure. In compression volume [12], where a pistoncylinder arrangement allows storage of cold gas and its compression during
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interruption by movement of a piston [13] conventionally coupled to the
operating mechanism/drive [18]. Fresh gas is collected and retained in this
volume during closing operation. In expansion volume [11], where the
available gas is directly exposed to arc during contact separation/ arcing.
The third volume is an intermediate volume [09E], where stored gas is
compressed by expansion volume [11] gas and where gas pressure rises
during arcing period due to both compressions by expansion volume gas
and by mixing. There is an additional volume in series to compression
volume called as protection volume [09B].
[076] At the end of stroke during opening operation this volume helps to
avoid in creating excessive gas pressures and will not load the mechanism.
[077] In closed condition, there is no flow of gas either through the nozzle
[10] or right hand pole assembly openings. During opening operation when
the pin/ movable fixed contact [20] moves and is released from the socket
[09], a fraction of arced gas is disposed to the main volume [31] through the
vents in the pull tube [16]. Piston [13] is connected to puffer base [14] which
is further connected to support plate / current transfer plate [37]. The puffer
base [14] is connected to the second FRP insulator [05] through an
intermediate housing [33] arrangement.
[078] The arcing insulator [36] and the second FRP insulator [05] are
connected through an intermediate housing [33] which has ports for
discharge of hot gas and mix with main volume [32]. A current transfer
housing [15] is kept on intermediate housing [33] to extend high voltage
connection from gas circuit breaker pole through bottom HT terminal [38].
The pull tube [16] is at the center of puffer / compression volume [12] and
surrounded by pressurized gas during opening condition. Sometimes, if
there is a miss location of pull tube vent, the hot gas can go towards
compression volume [12] externally and spoil the compression volume [12]
within few fault current interruptions.
[079] Figure 3 illustrates Left hand and right hand pole assemblies in
combination located in horizontally mounted gas circuit breaker enclosure
in accordance with the prior art.
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[080] In general, all the above- mentioned components are present in the
circuit breaker. The only concern is to make the gas circuit breaker compact
so that it can easily be fitted in a less space. Therefore, the horizontally
mounted gas circuit breaker enclosure [01] circuit breaker is proposed.
[081] Figure 4 illustrates a block diagram of the horizontally mounted gas
circuit breaker enclosure [01] with two FRP insulators having symmetrical
structure in accordance with a present invention.
[082] A horizontally mounted gas circuit breaker enclosure [01] is divided
into two shells. First shell is called left hand side pole shell [01A]. Second
shell is called right hand side pole shell [01C]. Each shell is a four-way
connector and is joined by standard tube [01B]. The gas circuit breaker
enclosure assembly is basically made from standard tube with total of six
ports.
[083] The left hand side pole shell [01A] has mainly three ports. First one
(port I [01D]) is for integration to epoxy support insulator [02]. The second
port of left hand side shell (port II [01E)] is connected to first FRP insulator
[03] through spherical dish cover [04]. Here, there is requirement of an
additional insulator that is required to guide the spherical dome [28]. The
third port (port III [01F]) is connected to epoxy support insulator [02].
[084] The right hand side shell [01C] also has three ports. First port (port
IV [01G]) is for integration to epoxy support insulator [02]. The second port
of right-hand side shell (port V [01H)] is connected to second FRP insulator
[05] through support plate [06] and mechanism housing [07]. The third port
of right hand side shell (port VI [01I]) is connected to spherical dish with
moisture absorbents [08].
[085] Here only one epoxy insulator is used as in order to accommodate
an epoxy insulator, an additional component is required to be located on the
gas circuit breaker enclosure [01]. Because of epoxy insulator, additional
spherical Cover-II [39], HT terminal [38], HT shield [40] and terminal shield
[41] are required. Hence, the FRP insulator (shown in Figure 6) is
introduced that avoid the use of an additional epoxy insulator. Moreover,
addition of an extra epoxy insulator increases the dimensions of gas circuit
breaker enclosure [01].
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[086] Here, the left hand side shell and right hand side shell are
symmetrical and congruent.
[087] Figure. 5 illustrates the complete assembly and the components of
the proposed horizontally mounted gas circuit breaker enclosure with
increased efficiency in accordance with an embodiment of the present
invention.
[088] In the present invention, the spherical dome [28] of pole assembly is
guided by using a first FRP insulator [03] as shown in FIG.7 made of fibre
reinforced plastic (FRP) insulation. This first FRP insulator [03] is made as
short as possible in length that helps in achieving the lowest possible
electrical field levels around spherical dome [28] and insulator itself.
[089] In addition, the first FRP insulator [03] is used to guide the spherical
dome [28] so that additional epoxy insulator [02] is not required to guide the
spherical dome [28]. Because of this epoxy insulator [02], the dimensions
of gas circuit breaker enclosure [01] increases. To accommodate epoxy
insulator [02], additional components are required to be located on the gas
circuit breaker enclosure [01]. Because of epoxy insulator [02], additional
spherical Cover-II [39], HT terminal [38], HT shield [40] and terminal shield
[41] are required.
[090] By proposing the first FRP insulator [03], components like spherical
Cover-II, HT terminal, HT shield, and terminal shield are completely
eliminated. The special insulator [03] made of Fibre Reinforced Polymer
(FRP) or Kevlar or equivalent material is fixed to spherical dome [28]
through spherical dome member [28A] and other end it is plugged into a
cover plate [42] which is fixed to the Gas circuit breaker enclosure [01].
[091] The First FRP insulator [03] comprises a FRP tube having two
terminals one is at high voltage potential and other is at ground potential.
The high voltage terminal [03A] and FRP tube [03B] are fixed through
special gluing [03D] and similarly the grounded terminal [03C] and the FRP
tube [03B] is also fixed through special gluing [03D]. The grounded terminal
[03C] is placed at a gas gap of “G” with the high voltage terminal [03A] as
shown in FIG.6.
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[092] Precisely, in GCB enclosure [01] the discharge /radial distance “G”
is maintained relatively small between the grounded terminal [03C] and the
high voltage terminal of special insulator [03A] to meet tensile and
compression requirements. Precisely gluing is required on either side of
special insulator [03] (refer Figure 6). To improve the distance “G”, the
grounded terminal [03C] is located inside the cover plate [42] in strategic
manner. Further, the high voltage terminal of special insulator [03A] is fixed
to the spherical dome [28] of GCB pole assembly.
[093] The gas gaps “G1” and “G2” as shown in FIG.6 are designed in such
a way that influence of electric stress on tri-junction formed by FRP, gas
and high voltage terminal is nullified and highest stress point is shifted to
Spherical Dome [28] which is well below acceptable level. By doing so, the
tangential stress on FRP insulator [03] is reduced significantly and may not
generate discharge during service. For high voltage applications, the high
voltage and grounded terminals [03A,03C] require good profiles and occupy
larger dimensions.
[094] FIGURE.8 shows the design of spherical cover in accordance with
the present invention.
[095] As mentioned above, the open end of epoxy insulator [02] is
integrated with terminal shield [44] to limit electrostatic field. Suitable
spherical Cover-II [39] is used to provide necessary insulation gap between
terminal shield [41] and ground. In case of epoxy insulator [02] integrated
through bus multi-module assembly [43] has HT shield [40] on either side
and supported from pole assembly through HT terminal [38]. The spherical
Cover-II [39] and the spherical cover [04] has designed in such a manner
that it reduces the amount of mechanical stresses applied. Both the
spherical cover has spherical profile with its predefined radius to limit
mechanical stresses under high pressure conditions. The radius (R) of dish
is maintained to be 80 to 100 % of Inner diameter (D) of the dish cover. The
structure of the spherical cover-II is made in such a manner that the
mechanical stresses are found to be bare minimum even under fault
conditions.
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[096] FIGURE. 9 shows the double bus Hybrid gas insulated switchgear
bay with horizontally mounted gas circuit breaker.
[097] In GIS or in hybrid gas insulated switchgear bay, there are mainly
two parts. One is bus multi-module assembly [43] and other one is feeder
multi-module assembly [45]. These two sections are electrically separated
by using horizontally mounted gas circuit breaker [46]. To create provisions
of necessary isolation of switchgear bay disconnector cum earthing switch
[47] is accommodated on either side of gas circuit breaker [46]. The earthing
switches are again may be maintenance or fault proof [48,49] depending on
its location in switchgear bay. The disconnector switch is being operated
through DS drive housing [50] and earthing switch is being operated through
ES drive housing [51]. On Bus side, these disconnector cum earthing
switches [47] are terminated with compact/ segregated phase bus
depending on voltage class.
[098] On Feeder side, these switches are terminated with surge arrester
[52] and potential transformer [53] on one side. On other side these switches
are terminated with current transformer [44]. The terminal equipment may
be gas-to-cable termination or gas-to-air bushing [54] or gas-to-oil bushing
or gas insulated bus duct [55]. The invention of horizontally mounted gas
circuit breaker [46] along with bus and feeder multi-modules [43,45]
facilitate an optimal double bus gas insulated switchgear or hybrid gas
insulated switchgear with all possible configurations of high voltage
switchgear layout. With proposed horizontally mounted gas circuit breaker,
cost of product, number of leakage points and foot print dimensions are
reduced significantly
[099] Thus, with the assembly described herein in the present disclosure,
various technical problems of the state of the art are resolved. Also,
although a number of exemplary method options are described herein,
those skilled in the art can appreciate that the horizontally mounted circuit
breaker can easily be accommodated inside the hybrid gas insulated switch
gear without deviating from the scope of the subject matter of the present
disclosure.
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TECHNICAL ADVANTAGES
[100] The present invention proposes horizontally mounted gas circuit
breaker with dual motion contact system.
[101] The present invention proposes horizontally mounted gas circuit
breaker with dual motion contact system and dynamic field electrode.
[102] The present invention proposes horizontally mounted gas circuit
breaker with pole assembly supported by epoxy insulators and FRP
insulator housings.
[103] The present invention proposes horizontally mounted gas circuit
breaker with horizontal support from insulating tube on either end of pole
assembly.
[104] The present invention proposes horizontally mounted gas circuit
breaker pole assembly supported by four to five insulators depending type
of configuration
[105] The present invention proposes horizontally mounted gas circuit
breaker pole assembly supported by a support insulator by using spherical
dome as high voltage shield.
[106] The present invention proposes horizontally mounted gas circuit
breaker pole assembly supported by the support insulator which is plugged
into spherical disc cover assembly of circuit breaker enclosure.
[107] The present invention proposes the horizontally mounted gas circuit
breaker with minimum number of cone or disc epoxy insulators for
supporting circuit breaker pole assembly.
[108] The present invention proposes the support insulator to guide
spherical dome of left hand pole with lowest possible discharge / radial
distance.
[109] The present invention proposes the support insulator without
additional high voltage or grounded metallic shields.
[110] The present invention proposes the support insulator such that the
mechanical strength of insulator is ensured by using appropriate gluing
techniques.
[111] The present invention proposes a spherical dish cover to guide pole
assembly of horizontally mounted gas circuit breaker.
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[112] The present invention proposes a spherical cover to create
necessary insulation and to limit mechanical stresses against high
pressures encountered during severe fault conditions.
WORKING OF INVENTION
[113] As mentioned above Hybrid gas insulated switchgear is a condensed
switchgear which is mainly used in the renovation and extension of
substations with AIS based switchgear where such modifications are
required to be accomplished keeping the substation in service. Expensive
land rates, unavailability of free land alongside and increasing intricate
approval procedures have made ‘space and time’ the main cost factor in the
development of substations. Hybrid switchgear provides the opportunity to
adapt a substation to modern world’s demands in the express time and most
importantly, without the requirement for further space as it has circuit
breakers, earthing switches, dis-connectors and current transformers (all
housed in a pressure defiant and gas tight enclosed space. The proposed
horizontally oriented circuit breaker can easily fulfil all the requirements of
the hybrid gas insulated switch gear.
Test Results
[114] As per the requirement, the Gas gap “G” achieved is <200 mm for
420 kV gas circuit breaker and DISH cover D is less than 540 mm.
[115] Further, it will be appreciated that those skilled in the art will be able
to devise various arrangements that, although not explicitly described or
shown herein, embody the principles of the invention and are included within
its scope.
[116] Furthermore, all examples recited herein are principally intended
expressly to be only for pedagogical purposes to aid the reader in
understanding the principles of the invention and the concepts contributed
by the inventor(s) to furthering the art and are to be construed as being
22
without limitation to such specifically recited examples and conditions. Also,
the various embodiments described herein are not necessarily mutually
exclusive, as some embodiments can be combined with one or more other
embodiments to form new embodiments.
[117] While the foregoing describes various embodiments of the invention,
other and further embodiments of the invention may be devised without
departing from the basic scope thereof. The scope of the invention is
determined by the claims that follow. The invention is not limited to the
described embodiments, versions or examples, which are included to
enable a person having ordinary skill in the art to make and use the
invention when combined with information and knowledge available to the
person having ordinary skill in the art.
23
WE CLAIM
1. A horizontally mounted gas circuit breaker [01] for hybrid gas insulated
switch gear comprises
a left hand side pole shell [01A] having three ports, wherein a first
port [01D] and third port [01F] being connected to an epoxy support
insulator [02], a second port [01E] being connected to a first FRP
insulator; and
a right hand side pole shell [01C] having three ports, wherein a first
port [01G] being connected with the epoxy support insulator [02], a
second port [01H] being connected to second FRP insulator [05]
through support plate [06] and mechanism housing [07], a third port
[01I] being connected to a spherical dish with moisture absorbents
[08];
wherein the left hand side and the right hand side pole shell includes
a four-way connector and being joined by a standard tube [01B].
2. The horizontally mounted gas circuit breaker as claimed in claim 1, wherein
the epoxy support insulator [02] is covered by a spherical Cover-II [39],
an HT terminal [38], an HT shield [40] and a terminal shield [41].
3. The horizontally mounted gas circuit breaker as claimed in claim 2, wherein
the spherical cover [39] includes a spherical profile having radius (R) that
needs to be 80 to 100 % of Inner diameter (D) of the dish cover.
4. The horizontally mounted gas circuit breaker as claimed in claim 1, wherein
the tube (03B) of the FRP insulator [03,05] is made of a material including
FRP / Kevlar.
24
5. The horizontally mounted gas circuit breaker as claimed in claim 3, wherein
a first end of the tube [03B] of the FRP insulator [03,05] is connected to a
ground terminal (03C).
6. The horizontally mounted gas circuit breaker as claimed in claim 3, wherein
a second end of the tube [03B] of the FRP insulator [03,05] is connected to
a high voltage terminal (03A).
7. The horizontally mounted gas circuit breaker as claimed in claim 3, wherein
the high voltage terminal (03A) and tube (03B) of FRP insulator (03) is fixed
through gluing and the grounded terminal (03C) and tube (03B) of FRP
insulator (03) is also fixed through gluing.
8. The horizontally mounted gas circuit breaker as claimed in claim 3, wherein
the high voltage terminal (03A) and grounded terminal (03C) of the tube
(03B) of the FRP insulator (03) are fixed, that lowest possible radial
/discharge distance, “G” can be achieved and sufficient gluing length of
these terminals (03A,03C) can be ensured.