Patent Publication Number: US-11049645-B2

Title: Transformer with air guiding plates

Description:
TECHNICAL FIELD 
     Example embodiments disclosed herein generally relate to a transformer, more specifically, to an open wound dry-type transformer with air guiding plates. 
     BACKGROUND 
     Like all of the electrical distribution equipment serving critical systems, transformers are key components widely used, with various types and specifications. For example, large dry-type distribution transformers are typically fed by medium-voltage power systems (tens of kilovolts) and feature a secondary voltage rating of 480V, 3-phase. Some of the larger common sizes of dry-type transformers available today have a capability up to tens of MVA (million VA). In these transformers, large current generates dramatic heat. Therefore, heat dissipation is vital when designing a distribution transformer. 
     An open wound dry-type transformer normally has a number of coils which are in the form of stacks of wire disks. Normally, the wire disks are stacked vertically. Currently, heat dissipation can be achieved by a fan disposed at the bottom of the stacks, but the fan is not able to effectively reduce the temperature deep inside the stacks. 
     SUMMARY 
     Example embodiments disclosed herein propose a structure of a transformer in which heat can be dissipated more effectively. 
     In one aspect, example embodiments disclosed herein provide a transformer. The transformer includes: a first coil including a first stack of wire disks stacked in a first direction; an exterior barrier arranged to form a first air gap between outer sides of the wire disks of the first stack of wire disks and the exterior barrier; an interior barrier arranged to form a second air gap between inner sides of the wire disks of the first stack of wire disks and the interior barrier; a wind generator arranged to generate an air flow in the first direction; a core in the form of a cylinder that is surrounded by the first coil; and an air guiding plate fixed to one of the exterior barrier and the interior barrier, to guide the air flow in a second direction along first stack gaps between the wire disks of the first stack of wire disks. 
     Through the following description, it would be appreciated that the transformer according to the present disclosure provides an effective structure by which the air flow can be directly thoroughly among the wire disks in the transformer, which in turn improve the efficiency of active dissipation. In this way, the dimension of the transformer can be reduced, because even a smaller gap between the wire disks can result in an improved performance of heat dissipation by the structure according to the present disclosure. In addition, material costs can be lowered because less material is required for passive heat sinks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Through the following detailed descriptions with reference to the accompanying drawings, the above and other objectives, features and advantages of the example embodiments disclosed herein will become more comprehensible. In the drawings, several example embodiments disclosed herein will be illustrated in an example and in a non-limiting manner, wherein: 
         FIG. 1  illustrates a schematic section view of a transformer in accordance with one example embodiment; 
         FIG. 2  illustrates a schematic section view of a transformer in accordance with another example embodiment; 
         FIG. 3  illustrates a perspective view of the transformer in accordance with one example embodiment, with its outer barrier and coils removed for showing how the air guiding plates are arranged; 
         FIG. 4  illustrates an air guiding plate in accordance with one example embodiment; and 
         FIG. 5  illustrates another air guiding plate in accordance with one example embodiment. 
     
    
    
     Throughout the drawings, the same or corresponding reference symbols refer to the same or corresponding parts. 
     DETAILED DESCRIPTION 
     The subject matter described herein will now be discussed with reference to several example embodiments. These embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the subject matter described herein, rather than suggesting any limitations on the scope of the subject matter. 
     The term “comprises” or “includes” and its variants are to be read as open terms that mean “includes, but is not limited to.” The term “or” is to be read as “and/or” unless the context clearly indicates otherwise. The term “based on” is to be read as “based at least in part on.” The term “being operable to” is to mean a function, an action, a motion or a state can be achieved by an operation induced by a user or an external mechanism. The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment.” The term “another embodiment” is to be read as “at least one other embodiment.” Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Furthermore, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. In the description below, like reference numerals and labels are used to describe the same, similar or corresponding pans in the several views of  FIGS. 1-5 . Other definitions, explicit and implicit, may be included below. 
       FIG. 1  illustrates a schematic section view of an example transformer  100 . The transformer  100  includes a first coil  110  and a second coil  120 . In one example, the first coil  110  is for high voltage while the second coil  120  is for low voltage. In some other examples, the first coil  110  is for low voltage while the second coil  120  is for high voltage. When the second coil  120  is arranged by stacking a number of wire disks, it can be structured in an analogous manner compared with the first coil  110 , and thus features with respect to the first coil  110  will be explained in detail in the following. 
     As shown in  FIG. 1 , the first coil  110  includes a first stack of wire disks  111  which are stacked along a vertical direction in this example. However, it is to be understood that in some circumstances, the wire disks  111  can be stacked with a different angle in relation to ground on which the transformer  100  is placed. A first coil  110  may consist of one or more coil stacks. In this example, the first coil  110  includes one coil stack surrounding a common axis (typically, there is a core  170  in the transformer  100  extending along the same axis, as shown in  FIG. 1 ). The one coil stack includes a number of wire disks  111  shaped as closed rings stacked bottom-up. There can be more than one coil stacks for the first coil  110 , each wire disk being shaped as a sector of a closed ring. In other words, each piece of the wire disks  111  can be in a shape of a closed ring or of a sector as a part of the closed ring. Wire disks and coils are widely known in the field of transformers, and thus their features, functions and connections are not to be described in detail. 
     A core  170  can be an iron core commonly used for various transformers. The core  170  shown in  FIG. 1  extends vertically in parallel with the direction D 1 . Although the core  170  is shown to be straight, it can be of other shapes such as a curve or a wave in some occasions. 
     An exterior barrier  130  is provided to form a first air gap  131  between outer sides of the wire disks  111  and the exterior barrier  130 . The exterior barrier  130  is used for guiding the air flow along the first air gap  131  so as to bring away the generated heat from the wire disks  111 . When the wire disks  111  are arranged in a way shown in  FIG. 1 , the first air gap  131  is extended in a vertical direction (D 1  or in parallel with D 1 ), and the outer sides of the wire disks  111  are the outer edges of the wire disks  111  with respect to the innermost core  170 . 
     An interior barrier  140  is provided to form a second air gap  141  between inner sides (named with respect to the outer sides) of the wire disks  111  and the interior barrier  140 . The interior barrier  140  is used for guiding the air flow along the second air gap  141  so as to bring away the generated heat from the wire disks  111 . When the wire disks  111  are arranged in a way shown in  FIG. 1 , the second air gap  140  is extended in the vertical direction (D 1  or in parallel with D 1 ), and the inner sides of the wire disks  111  are the inner edges of the wire disks  111  opposite to the outer edges of the wire disks  111 . 
     It is to be understood that, although  FIG. 1  shows a cylindrical transformer  100  in which the exterior harrier  130 , the interior barrier  140 , the first coil  110  and the wire disks  111  surround a common axis (which is coincided with the core  170  in this example), they can be arranged in other ways. For example, the transformer can be a cuboid or a cube instead of a cylinder, and the wire disks can be in a shape of rectangular or polygon instead of sector. The exterior barrier, the interior barrier, the coil(s) and the core can be arranged not in a coaxial way. The present disclosure does not intend to limit the shapes, forms, materials and dimensions of these components. 
     As shown in  FIG. 1 , at the bottom of the transformer  100 , one or more wind generators  150  can be provided to move (blow) air upward along the first and second air gaps  131 ,  141 . However, it is to be understood that the wind generator  150  can be placed atop the transformer  100  (to suck in air) so long as the wind is substantially generated from bottom to top. In this example, the wind generator  150  can be a fan. Because hot air moves upward in atmosphere, the wind moving upward will be more effective in terms of heat dissipation compared with the situation in which the wind flows down. The air flow generated by the wind generator  150  is along the first direction D 1  or in parallel with the first direction D 1 . In this example, the first direction D 1  is a substantially vertical direction. 
     One or more air guiding plates are fixed to at least one of the exterior barrier  130  and the interior barrier  140 . In one example, the air guiding plate is shaped to match the exterior barrier  130  or the interior barrier  140 , so that the existence of the air guiding plate blocks most of the air flow along the first air gap  131  or the second air gap  141 , respectively. As shown in  FIG. 1 , the air guiding plate may include two sets of plates, with the first set named to be one or more first air guiding plates  161  that are fixed to the exterior barrier  130 , and the second set named to be one or more second air guiding plates  162  that are fixed to the interior barrier  140 . Each of the first and second air guiding plates  161 ,  162  can protrude between adjacent wire disks  111  so that the air flow can be guided or directed in a second direction D 2  substantially perpendicular to the first direction D 1 . It is to be understood that the first or second air guiding plate  161 ,  162  may not necessarily protrude into the wire disks  111  so long as most of the air flow can be redirected into the wire disks  111 . The second direction D 2  is along first stack gaps  114  between the wire disks  111 . In this example, the second direction D 2  can face toward the core  170  or face away from the core  170 , and the first direction D 1  can be angled with respect to the second direction D 2  by an angle between 80 to 100 degrees. 
     The air flow generated by the wind generator  150  may travel in the following way. First of all, the generated air flow moves upward along the first air gap  131  until impinging on one of the first air guiding plate  161 . Due to the blockage of the first air gap  131  by the first air guiding plate  161  fixed to the exterior barrier  130 , the air flow will be redirected to move toward the interior barrier  140  via a number of first stack gaps  114  until impinging on die interior barrier  140 . Then, the air flow is forced to move upward along the second air gap  141  until impinging on one of the second air guiding plate  162  fixed to the interior barrier  140 . Due to the blockage of the second air gap  141  by the second air guiding plate  162 , the air flow will be redirected to move toward the exterior barrier  130 . 
     In this example, there are multiple first air guiding plates  161  provided on the exterior barrier  130 , and multiple second air guiding plates  162  provided on the interior barrier  140 . Each of the first and second air guiding plates  161 ,  162  are placed at different altitudes, so that the route of the air flow meanders throughout the first stock of wire disks  111 . 
     In this way, the heat dissipation can be greatly improved, because the air flow passes almost each and every piece of the wire disks  111 . In particular, the middle portions of the wire disks generate a lot of heat that are otherwise unreachable by the air flow if no air guiding plate is provided. In other words, if no air guiding plate is provided, even if the heat near the outer sides and the inner sides can be brought away by the air flow easily, the heat generated by the middle portions of the wire disks  111  can only be conducted to the outer and inner sides in a passive way, which is inefficient. Therefore, the existence of the air guiding plate forces the air flow in substantially horizontal directions, which cools down the overall temperature within the transformer  100  dramatically. 
     In some cases, even one air guiding plate is effective enough to lower the temperature in the middle portions of the wire disks  111 . As such, the present disclosure does not intend to limit the quantity of the air guiding plate. In one example, the air guiding plate can protrude into the first stack of wire disks  111  to an extent that most of the air flow along either the first air gap  131  or the second air gap  141  is forced to change its travelling direction. As mentioned above, the air guiding plate may not protrude into the wire disks  111  as well, as long as a portion of the air flow is redirected into the first stack gap  114 . 
     In one example, the first air guiding plate  161  (if existing) is fixed to the exterior barrier  130  in an air tight manner, and the second air guiding plate  162  (if existing) is fixed to the interior barrier  140  in an air tight manner. In this way, almost all the air flow will be redirected by die air guiding plate(s), forming a complete meander route passing through the wire disks. However, in another example, some holes or openings can be provided on the air guiding plate(s) as well. The area of the openings on the air guiding plate can be controlled so that the route of the air flow can be controlled accordingly. 
     Additionally or alternatively, the transformer  100  may include a second coil  120 . In the example shown in  FIG. 1 , the second coil  120  includes a second stack of wire disks  121 , and the second coil  120  is arranged between the core  170  and the interior barrier  140 . A third air gap  132  is formed between the interior barrier  140  and outer sides of the wire disks of the second stack of wire disks  121 , and a fourth air gap  171  is formed between the core  170  and inner sides of the wire disks of the second stack of wire disks  121 . The outer sides of the second stack of the wire disks  121  approximate the interior barrier  140 , and the inner sides of the second stack of the wire disks  121  approximate the core  170  and are opposite to the outer sides the second stack of the wire disks  121 . The core  170  may or may not include a separate barrier. 
     In the example shown in  FIG. 1 , the wire disks of the second stack of wire disks  121  are arranged to be in parallel with the wire disks of the first stack of wire disks  111 . The air flow generated by the wind generator  150  may be directed along the third air gap  132  and the fourth air gap  171 . However, in some other examples (such as the one shown in  FIG. 2 , which is to be discussed in the following), one of the first and second coils  110 ,  120  can be arranged so that its wire disks are oriented vertically instead of horizontally. 
     A third air guiding plate  163  may be fixed to the interior burner  140  and a fourth air guiding plate  164  may be fixed to the core  170 . Both of the third air guiding plate  163  and the fourth air guiding plate  164  may protrude between adjacent wire disks of the second stack of wire disks  121  to guide the air flow in the second direction D 2  along second stack gaps  124  between the wire disks of the second stack of wire disks  121 . 
     In another example, the second coil  120  may surround the core  170  and be arranged to be coaxial with the core  170 , the exterior barrier  130  and the interior barrier  140 . The third air guiding plate  163  may be in the form of a closed ring to be circumferentially fixed to the interior barrier  140 , and the fourth air guiding plate  164  may be in the form of a closed ring to which the core  170  is circumferentially fixed. The third air guiding plate  163  may be fixed to the interior barrier  140  in an air tight manner, and the fourth air guiding plate  164  may be fixed to the core  170  in an air tight manner. 
     The arrangements of the components associated with the second coil  120  and the third and fourth air guiding plates  163 ,  164  may be in similar ways to those associated with the first coil  110  and corresponding air plate(s). The advantages brought by the third and fourth air guiding plates  163 ,  164  to the second stack of wire disks  121  are also related to the heat dissipation between the wire disks  121 , and thus detailed descriptions will be omitted. 
     It should be understood that, although  FIG. 1  illustrates that both the first coil  110  and the second coil  120  are arranged with each of the wire disks extending horizontally, one of the first and second coils  110 ,  120  can be arranged such that its wire disks extend vertically. The vertically arranged wire disks can be embodied in  FIG. 2 , in which the second coil  220  is provided which includes a number of wire disks  221  for a transformer  200 . Given that the wire disks  221  extend vertically, the wire disks  221  can be arranged substantially coaxial with the core  170 . Thus, the existence of the air guiding plate(s) is not necessary because the wind generator  150  placed at the bottom (or top) of the transformer  100  moves up the air flow through the stack gaps easily. 
     There can be more or less coil(s) in the transformer  100 . For example, the interior barrier  140  can be regarded as the exterior surface of the core  170  in some cases where the second coil  120  or  220  does not exist, and thus the first coil  110  is located between the core  170  and the exterior barrier  130 . In other scenarios, additional coil(s) may be stacked atop the existing coil(s) as well. 
       FIG. 3  illustrates a perspective view of the transformer  100 , with its first (outer) barrier  130  and coils  110  removed for showing how the air guiding plates are arranged. As shown in  FIG. 3 , a number of ridges  142  are provided on the interior barrier  140 , and they are spaced equally with each other in this example. The exterior barrier  130  is omitted in this figure, on which a number of ridges may be provided as well. The second air guiding plates  162  are directly fixed to the interior barrier  140 . The ridges  142  may provide a separation for different sets of the first coils  110 , as described above. Connecting members  143  may be provided on the ridges  142  for holding the first air guiding plates  161 . In this way, the first and second air guiding plates  161 ,  162  are placed at different altitudes. 
       FIGS. 4 and 5  show the first and second air guiding plates  161  and  162  respectively. In these examples, the first air guiding plate  161  is in the form of a closed ring to be circumferentially fixed to the exterior barrier  130 , and the second air guiding plate  162  is in the form of a closed ring to which the interior barrier  140  is circumferentially fixed. There are some protrusions  165  on the outer circumference of the first air guiding plate  161  for engaging with the connecting members  143 . There are some notches  166  on the inner circumference of the second air guiding plate  162  for engaging with the ridges  142  on the interior barrier  140 . The third and fourth air guiding plates  163 ,  164  can be arranged in similar ways. 
     From simulation results, by arranging a meander route with five first air guiding plates and five second air guiding plates for a stack of wire disks having a height of 123 cm and having air gaps of 2.2 cm, the temperature at the coil can be significantly reduced. Compared with a model without any air guiding plate, for the model having five first air guiding plates and five second air guiding plates, the average temperature at the coil can be lowered by about 30 degrees Celsius from 80° C., and the highest temperature during the simulation period at the coil can be lowered by about 20 degrees Celsius from about 100° C. 
     While operations are depicted in a particular order in the above descriptions, it should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several details are contained in the above discussions, these should not be construed as limitations on the scope of the subject matter described herein, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. On the other hand, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.