Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TRANSFORMER COOLING STRUCTURE WITH
U-SHAPED COOLING PANELS
BACKGROUND OF THE INVENTION
Field of the Invention:
This invention relates to a heat exchange unit
for cooling of dielectric fluid of an electrical trans-
former or other device employing a circulating fluidcoolant.
De c~E_ion of the Prior Art:
Electrical apparatus, such as transformers or
induçtion regulators, is placed within a tank and immersed
in a bath of insulating and cooling oil, which insulates
varicus parts of the apparatus from one another, and, by
circulation and conduction transfers the heat qenerated in
the apparatus to the walls of the tank. To facilitate
removal of heat from the walls, cooling panels or heat
exchangers are mountad on the walls for dissipating the
heat to ambient air.
Associated with the foregoing have been problems
of transformer size and efficiency. More particularly, it
is desirable to minimize the volume of cooling fluid in
the transformer in order to reduce the unit volume and
therefore the cost of the cooling fluid and the supporting
structure.
SUMMARY OF THE INVENTION
In accordance with this invention, the foregoing
problems may be overcome by providing a tank for a trans-
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former submerged in a cooling fluid, the tank ~omprising apreferably rectan~ular cross-section having opposite side
walls, a plurality of cooling panels extending outwardly
from the plane of at least one side wall which panel
comprises a pair of oppositely disposed sheet metal sides
having facing peripheral edges and end portions that are
secured together in a fluid-tight seal, the facing sides
of adjacent panels comprising two legs of a U-shaped
channel including a bight portion in between, each sheet
metal side being formed to include a coolant fluid outlet
header near one end and a coolant fluid inlet header at
the other end, and the panels including gas storage means
on the side of the coolant fluid outlet header opposite
that of the coolant fluid inlet header.
The advantage of the tank structure of this
invention is that inasmuch as each transformer has a
prescribed required volume for gas, the gas header in the
coolant panels provides storage space in communication
with the top of the transformer, whereby the top portion
of the transformer may be reduced in size.
RIEF DESCRIPTION OF THE DRAWINGS
Figure l is a schematic view of a transformer
tank with heat exchanger panels extending from opposite
6ides thereof in accordance with this invention;
Figure 2 is a horizontal sectional view taken on
the line II-II of Figure l;
Figure 3 is an enlarged elevational view, taken
on the line III-III of Figure l of a cooling panel, with
an associated transformer tank portion shown partially ln
section;
Figure 4 is an enlarged elevational view of
another embodiment of the panel showing spot weld locations
without vertical channels formed into the panel sides;
A Figure 5 is a schematic vie~ showing the panel
embodiment of Figure 3 having spot welds along the vertical
channels of the panel side;
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Figure 6 is a schematic view of the panel of
Figure 4 showing the location of spot welds without panel
channels; and
Figure 7 is a vertical sectional view taken on
the line VII-VII of Figure 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In Figure 1 a transformer structure is generally
indicated at 11 and it comprises a tank 13 which contains
a transformer unit 15, and which includes two banks 17, 19
of heat exchanger panels 21 extending from opposite sides
of the tank.
Although the tank 13 is described as containing
a transformer unit 15, it is understood that other elec-
trical apparatus that is operated and submerged ~ithin a
cooling or dielectric fluid 22 (Figure 3) is within the
scope of this invention.
The transformer structure 11 is comprised of a
pair of opposite end walls 23, 25, a bottom wa:L1 27, a top
wall 29, opposite side walls 31, 33 on which the heat
exchanger panels 21 are mounted. Four similar support
braces or angle members 35 are located at the corners
where the several walls converge. The walls 23, 33 and
braces 35 are secured together in a suitable manner, such
as by welds, along adjacent edges to form the rectangular
tank structure (Figure 1~. It is understood, however,
that any other structure, such as octagonal or cylindrical,
may be used. Also, although two heat exchanger banks 17,
19 are provided on opposite sides, any other nu~ber of
banks, such as one bank 17, or three or more banks of
similar structure, may be provided on corresponding exter-
nal walls of the tank.
To facilitate assembly and rigidity of structure,
the end walls 23, 25 include similar flanges 37, 39. The
flanges 37 at the lower ends of the end walls 23, 25
cooperate with the angle members 35 to reinforce each
other. Bars 40 reinforce the bottom wall and contribute
to the rigidity of the planar end walls 23, 25. The
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flanges 37 at the upper end of the end walls likewise
cooperate with the upper pair of angle members 35 for
reinforcing the members with the walls and for providing a
base for welding of the top wall 29 in place. The inturned
flanges 39 on both end walls provide a base on which the
side walls 31, 33 are welded. The end wall 23 comprises
an opening 41 for the mounting of low voltage bushings
~not shown~. Likewise, the end wall 25 comprises a number
of openings 43 in which high voltage bushings ~not shown)
may be mounted. The openings 41, 43 are disposed merely
to indicate that such bushings may be mounted in the end
walls. Alternatively, the bushings may be mounted in
openings in the top wall 29.
Each heat exchanger panel 21 is comprised of a
lS pair of oppositely disposed sides 45, 47 ~Figure 2) which
are sheet-like members formed from sheet stock by rolling
in one direction to form oppositely disposed channels 4g
and 51. Corresponding pairs of corrugation~ ~9, 51 are
aligned and oppositely disposed to provide longitudinally
extending fluid flow conduits 53 between which convex
portions 55, 57 are disposed in aligned, surface-to-surface
contact for fluid-tight separation between adjacent con-
duits 53.
The panel sides 45, 47 also comprise convex
portions 59, 61 ~Figure 7), respectively, which extend
transversely of the panels and which are aligned ~Figure
7) to provide a fluid conducting header 63 ~Figure 3). A
similar fluid-conducting header 65 is provided at the
lower end of the panel by providing the panel sides 45, 47
with convex portions 67, 69, respectively. At the upper
end of the panel 21 a similar fluid-conducting header 71
is provided by forming convex portions 73, 75 at the upper
end of the panels 21. All of the fluid-conducting headers
63, 65, 71 are formed by the aligned corresponding conve~
portions that are preferably perpendicular to the conduits
53. When assembled, the upper and lower transverse ends
as well as the longitudinal edges are welded at 77, 79, 81
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in surface-towsurface, fluid-tight contact ~roviding a
fluid-tight panel which serves as a heat exchanger for the
cooling fluid from the interior of the tank 13, whereby
the fluid 2~ ~asses through an opening 82 to enter the
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5 header 63 and ~w vertically through the conduits 53 to
the header 65 from where it is return~ed through an opening
85 to the tank chamber.
In accordance with this invention, the facing
sides of adjacent panels 2 , such as oppcsite sides ~5a
and 47a (Figure 2), are integral with bight portion 87
which sides and portion constitute a U-shaped member
formed from sheet metal stock material. That is, the legs
45a, 47a and the bight portion 87 comprise a ~J-shaped
channel with the legs comprising opposite sides of adjacent
panels 21 when the bight portions form one outer wall of
the tank 13. The inner ends of opposite sides 45, 47 of
each panel are preferably welded at 89 which welds extend
between openings 91, 82, 85. The opening 91 t~igure 3) is
in the tank wall and communicates between the hoader 71
and the interior of the tank above the oil level 22,
whereby gas, such as nitrogen, is free to expand into the
header as well as the conduits 54 between headers 71, 63.
As the temperature of the transformer unit 13
increases during operation, the heated coolant fluid rises
to the level and moves through the openings 82, the headers
63, downwardly through the conduits 53 to the lower header
65 and then through the openings 85 to the lower portion
of the tank 13, thereby completing a cooling cycle. The
upper portions of the heat exchanging panels 21 above the
fluid-conducting headers 63, which comprise the upper ends
54 of the conduits 53 and the fluid-conducting header 71,
provide for gas circulation between the upper portion of
the tank 13 and the heat exchanging panels 21. An addi-
tional function of the upper portions of the panels is to
absorb expansion of the volume of the fluid wh~re excess
heating occurs. The upper portions of the several panels
21 above the fluid-conducting headers 63 extend to the
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upper end of the side walls and thereby resist excess
pressures in the tank.
Another embodiment of the invention is shown in
Figure 4 in which a panel 95 is substantially similar to
the panel 21 for which reason similar numerals refer to
similar parts. The panel 9~ differs from that of panel 21
in that opposite sides 97, 99 are provided with spaced
spot welds 101 disposed in a symmetrical pattern over and
between the panel sides 97, 99. In this manner, the
liquid coolant enters the panel 95 through the upper
header 63 and flows downwardly through the panel around
and between the several spot welds 101 to the lower header
65.
For a comparison of the difference in structure
of the panels 21, 95, reference is made to Figures 5 and
6, respectively. Thus, the panel 21 includes a plurality
of spaced vertical channels 49 which are lined with corre-
sponding channels 51 which are held together by spaced
spot welds 103 to form vertical conduits 53 through which
the dielectric fluid 2~ passes in heat exchange relation
with the ambient atmosphere. The panel 95 (Figure 6),
however, includes only spot welds 101 for holding the
opposite sides 97, 99 together so that the dielectric
fluid is free to flow around and between the spot welds in
vertical as well as lateral movement.
In conclusion, the transformer structure of this
invention incorporates the coolers, or heat exchange
units, with the tank wall function. The cooler panels are
assembled by providing peripheral welds along the joining
edges of U-shaped panel structures having a common bight
portion which forms the outer wall of the transformer.
Finally, each transformer has a required volume of gas for
which a gas header is provided in the panels of fins which
is used as part of the gas space.
