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EP 3 627 522 A1 |
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EUROPEAN PATENT APPLICATION |
(43) |
Date of publication: |
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25.03.2020 Bulletin 2020/13 |
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Date of filing: 24.09.2018 |
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(51) |
International Patent Classification (IPC):
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(84) |
Designated Contracting States: |
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AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL
NO PL PT RO RS SE SI SK SM TR |
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Designated Extension States: |
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BA ME |
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Designated Validation States: |
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KH MA MD TN |
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Applicant: ABB Schweiz AG |
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5400 Baden (CH) |
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Inventors: |
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- SITKO, Adam
30-552 Krakow (PL)
- NOWAK, Remigiusz
30-691 Krakow (PL)
- OGANEZOV, Valeri
Verdun H3E1S1 (CA)
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(74) |
Representative: Chochorowska-Winiarska, Krystyna |
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ABB Sp. z o. o.
ul. Zeganska 1 04-713 Warszawa 04-713 Warszawa (PL) |
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(54) |
GAS INSULATED ELECTRICAL SWITCHGEAR |
(57) The subject of the invention is a gas insulated electrical switchgear (1) placed
in an enclosure (2) and provided with at least one bushing (4) for transferring electric
energy through the enclosure of the switchgear. The bushing (4) has a conductor (5)
for powering the switchgear (1) and has a form of a the cooling device which is integrated
in the conductor (5) of the bushing (4). The cooling device is a heat pipe filled
with a working fluid (8). One end of the heat pipe forms an electrical bottom terminal
(11) connected with a conductive part of the switchgear (1) whereas the other end
of the heat pipe forms an electrical top terminal (12) placed outside the enclosure
(1) closing the switchgear (1).
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[0001] The subject of the invention is a gas insulated electrical switchgear placed in the
enclosure and provided with at least one bushing for transferring electric energy
through the enclosure of the switchgear.
[0002] From patent
EP2494567 there is known a medium voltage apparatus closed in the enclosure and having a device
for cooling the medium voltage apparatus. The device for cooling is using heat pipes,
partially consisted in a casing of the apparatus. The heat pipe is filled with a working
fluid. The part embedded into casing has an evaporator being in contact with current
conducting part of the device connected by sleeve with condensation device placed
outside the device. The sleeve is made of electrically insulating and thermally well
conductive material. The disadvantage of this solution is the need of using insulating
sleeve which must provide electrical separation between current path of medium voltage
apparatus and the casing. In addition this arrangement require to provide a space
for placing there a separate auxiliary cooling system, thus the size of the medium
voltage apparatus need to be extended.
[0003] From patent
US7253379 there is known a high voltage circuit breaker with cooling system in the form of
a heat pipe. The heat pipe is a device having a sealed chamber for working fluid circulation.
The working fluid circulates in liquid and gaseous phase. The circulation allows effective
heat transfer between evaporator, where heat is absorbed by evaporation process, and
condenser, where heat is released during condensation. The working fluid used in the
heat pipe must have suitable dielectric strength because it circulates between evaporator
placed on a conductive part of the circuit breaker being on high electrical potential
and the condenser attached to grounded housing.
[0004] The essence of the present invention having a cooling device with a phase - change
heat transfer fluid is that the switchgear is equipped with at least one bushing with
a conductor for powering the switchgear and in the same time a cooling device which
is integrated in the conductor (5) of the bushing (4) that forms a heat pipe. The
heat pipe is filled with a working fluid. One end of the heat pipe forms an electrical
bottom terminal connected with a conductive part of the switchgear whereas the other
end of the heat pipe forms an electrical top terminal placed outside the enclosure
of the switchgear. The heat pipe has a vaporizing part situated in the proximity of
the bottom terminal and a condensing part situated in the proximity of the top terminal.
[0005] Preferably an upper part of the conductor of the busing is connected with a heat
sink device.
[0006] Preferably a bottom part of the conductor of the busing together with the bottom
terminal are free of an insulation.
[0007] Preferably the inner side of the cylinder of the conductor of the bushing is covered
with a wick.
[0008] Preferably the wick has a form of a well-developed surface structure made on the
inner side of the cylinder of the conductor of the busing.
[0009] Alternatively the wick has a form of a separate layer deposed on the inner side of
the cylinder of the conductor of the busing.
[0010] The advantage of the present invention is that the cooling device is integrated within
existing and irreplaceable part of the switchgear, i.e. the conductor of the busing,
what does not require any additional electrical insulation. Moreover, the cooling
device is embedded in a current path of the switchgear what causes that the heat is
transferred directly out of place where it is generated by Joule's heating. Such arrangement
allows for design of a compact electrical switchgear without any additional volume
for placing there a separate cooling device.
[0011] The present invention is presented in an exemplary embodiment were:
Fig. 1 shows the switchgear placed in the enclosure and connected with the bushing
in a schematic view,
Fig. 2 shows the bushing from fig.1 in a cross-section,
Fig. 3 shows the bottom part of the bushing from fig.2 in a cross-section,
Fig. 4 shows the upper part of the busing from fig.2.
[0012] A switchgear 1 is placed entirely in an enclosure 2 filled with a gaseous medium
3. Conductive part of the switchgear is connected with a bushing 4 for transferring
electric energy delivered through the enclosure 2. The gaseous medium 3 could be air
or another gas for example SF6 or any other gas which provides sufficient voltage
withstand ability. The busing 4 is partially placed inside the enclosure and partially
outside the enclosure.
[0013] The busing 4 has a conductor 5 made of copper or aluminum, in the form of a metal
cylinder closed on both ends. The conductor is surrounded by an insulator 6 made of
thermoplastic or thermosetting material which provides sufficient thickness for electrical
insulation in relation to the rating voltage of the switchgear. The insulator 6 extends
radially along the axis of the conductor 5 but not covering the both ends of the conductor
5. The insulator 6 is attached to a flange 7 made of steel or aluminum for mounting
the bushing in an opening made in a wall of the enclosure 2, what is not presented
in the drawing. Inside the conductor 5 there is a working fluid 8 in liquid and gaseous
state in thermodynamic equilibrium. The conductor 5 with the working fluid 8 form
a device commonly known as a heat pipe. The working fluid 8 must be delivered in amount
assured a space for condensation in a section provided for heat dissipation and in
amount sufficient to prevent full evaporation of the working fluid during maximum
operating temperatures provided for the switchgear. Typical material applicable for
working fluid are water, methanol or acetone. To enhance evaporation and condensation,
the inner side of the cylinder 5 is covered with a wick 9. The wick 9 may be realized
by preparing a special surface structure of inner side of the cylinder of the conductor
5, e.g. by grooving of the surface for receive well-developed surface structure, or
by deposition a separate layer of material with fabric or mesh-like structure characterized
by high thermal conductivity. The upper end of the bushing protruding from the enclosure
2 is equipped with a heat sink device 10 for better heat dissipation from the upper
end of the conductor 5. The heat sink is made of material with high thermal conductivity.
The ends of the conductor 5 form a bottom terminal 10 and a top terminal 12. The both
terminals 10 and 12 must be free of insulation to provide good electrical connection
and heat transfer. The switchgear 1 device is connected with electric line by top
terminal 12, what is not presented in the picture.
[0014] During the work of the switchgear 1 Joule's heat generated by conductive part of
the switchgear 1 is transferred by the bottom terminal 11 and heats the fluid 8 placed
in the bottom part of the conductor 8. A new thermodynamic equilibrium is reached,
where working fluid is boiling in bottom part of the conductor what is presented in
Fig.3 by the arrows. It is important that the bottom part of the conductor 8 is free
of any insulation protection what is needed for electricity conduction and heat transfer
from conductive part of the switchgear 1 to heat pipe. For phase change process and
working fluid transport enhancements wick 8 is used. When the evaporated fluid 8 reaches
the top part of the conductor 5 the gaseous phase of working fluid 8 starts to condensate
at wick 9 and inner wall of conductor. The wick 9 supports liquid phase transport
as it was indicated in the drawing 4 by dotted arrows. Heat is transferred via conductor
5 to the heat sink 10, which enhances heat dissipation. The presented conductor 5
of the bushing 4 plays role of the heat pipe placed inside the busing.
1. Gas insulated electrical switchgear (1) closed in an enclosure (2) fulfilled with
a gaseous medium (3), having a cooling device using a phase-change heat transfer fluid
characterized in that the switchgear is equipped with at least one bushing (4) with a conductor (5) for
powering the switchgear (1) and the cooling device is integrated in the conductor
(5) of the bushing (4) forms a heat pipe filled with a working fluid (8), wherein
one end of the heat pipe forms an electrical bottom terminal (11) connected with a
conductive part of the switchgear (1) whereas the other end of the heat pipe forms
an electrical top terminal (12) placed outside the enclosure (1) closing the switchgear
(1); the heat pipe has a vaporizing part situated in the proximity of the bottom terminal
(11) and a condensing part situated in the proximity of the top terminal (12).
2. Gas insulated electrical switchgear according to claim 1, characterized in that an upper part of the conductor (5) is connected with a heat sink device (10).
3. Gas insulated electrical switchgear according to claim 1-2, characterized in that a bottom part of the conductor (5) together with the bottom terminal (11) are free
of an insulation (8).
4. Gas insulated electrical switchgear according to claim 1-3, characterized in that the inner side of the cylinder of the conductor (5) is covered with a wick (9).
5. Gas insulated electrical switchgear according to claim 4, characterized in that the wick (9) has a form of a well-developed surface structure made on the inner side
of the cylinder of the conductor (5).
6. Gas insulated electrical switchgear according to claim 4, characterized in that the wick (9) has a form of a separate layer deposed on the inner side of the cylinder
of the conductor (5).
REFERENCES CITED IN THE DESCRIPTION
This list of references cited by the applicant is for the reader's convenience only.
It does not form part of the European patent document. Even though great care has
been taken in compiling the references, errors or omissions cannot be excluded and
the EPO disclaims all liability in this regard.
Patent documents cited in the description