DRY-TYPE TRANSFORMER

Abstract

 The present application provides a dry-type transformer, the dry-type transformer includes a base body, an iron core, a winding unit, and a fan. The winding unit and the fan are mounted on the base body, the winding unit includes a high-voltage winding, an insulation cylinder, and a low-voltage winding which are sequentially nested from outside to inside. The low-voltage winding includes a low-voltage winding body and a plurality of support strips, the low-voltage winding body is cylindrical, the plurality of support strips are arranged in the low-voltage winding body, and the plurality of support strips are distributed at intervals; a plurality of first grooves are provided on a side wall of the support strip and distributed at intervals along a longitudinal direction of the side wall, alleviating a technical problem of the dry-type transformer failures due to insufficient heat dissipation capability.

Description

[0001] The present application requires a priority of a Chinese patent application filed with the Chinese Patent Office on October 30, 2023, with application number 202311427705.7 and entitled "DRY-TYPE TRANSFORMER", the entire contents of the Chinese patent application are incorporated by reference in the present application.

FIELD

[0002] The subject matter herein generally relates to a field of transformer devices, and in particular, to a dry-type transformer.

BACKGROUND

[0003] A dry-type transformer mainly formed by an iron core, a low-voltage winding, and a high-voltage winding. During operation, the windings and the iron core may generate losses, and heat may be produced inside. When heat transfer is not rapid, heat accumulates inside the transformer. When an accumulated temperature exceeds a tolerance temperature of an insulation material, the insulation material may deteriorate. The operational reliability of the dry-type transformer largely depends on its insulation performance, which is closely related to the heat generation and heat dissipation capability inside the dry-type transformer. The dry-type transformer is prone to failures directly or indirectly due to abnormal temperatures.

[0004] The dry-type transformer mainly rely on natural convection and forced air cooling by fans for heat dissipation. Installing fans at a bottom of the transformer can enhance the heat dissipation capability of the dry-type transformer. To improve the heat dissipation capability of the dry-type transformer, the transformer is usually installed in a well-ventilated environment, fully utilizing a wind pressure from the natural environment to enhance a ventilation effect in the transformer. However, dry-type transformers inherently suffer from a problem of insufficient heat dissipation capacity, which often leads to failures.

SUMMARY

[0005] Accordingly, the present application provides a dry-type transformer to alleviate a technical problem of transformer failures due to insufficient heat dissipation capability.

[0006] The above objective of the present application can be achieved by adopting the following technical solutions.

[0007] First aspect of present application provides the dry-type transformer, the dry-type transformer includes a base body, an iron core, a winding unit, and a fan, the winding unit and the fan are mounted on the base body, the winding unit includes a high-voltage winding, an insulation cylinder, and a low-voltage winding which are sequentially nested from outside to inside; the low-voltage winding includes a low-voltage winding body and a plurality of support strips, the low-voltage winding body is cylindrical, the plurality of support strips are arranged in the low-voltage winding body, and the plurality of support strips are distributed at intervals; a plurality of first grooves are provided on a side wall of each of the plurality of support strips, and the plurality of first grooves are distributed at intervals along a longitudinal direction of the side wall; a plurality of protrusions are provided on an inner wall of the insulation cylinder, and/or the plurality of protrusions are provided on an outer wall of the insulation cylinder; at least two protrusions are arranged in groups; and for two protrusions arranged in groups, a distance between upper ends of the two protrusions is smaller than a distance between lower ends of the two protrusions.

[0008] In an exemplary embodiment, each of the plurality of support strips includes first supporting portions and second supporting portions which are alternately distributed, a cross section of the first supporting portion is different from a cross section of the second supporting portion, and the first groove is located on an outer side of the first supporting portion.

[0009] In an exemplary embodiment, a width of the first supporting portion is smaller than a width of the second supporting portion.

[0010] In an exemplary embodiment, a thickness of the first supporting portion in an inner-outer direction is greater than a thickness of the second supporting portion in the inner-outer direction.

[0011] In an exemplary embodiment, an upper end and a lower end of each of the plurality of support strips are formed two first supporting portions.

[0012] In an exemplary embodiment, cross sections of the first supporting portion and the second supporting portion are both rectangular.

[0013] In an exemplary embodiment, the two protrusions arranged in groups form a vortex generator, and a plurality of vortex generators are arranged at intervals in an up-down direction.

[0014] In an exemplary embodiment, a flow guide channel is provided between the upper ends of the two protrusions arranged in groups, and the flow guide channels of the plurality of vortex generators arranged at intervals in the up-down direction are aligned with each other.

[0015] In an exemplary embodiment, a plurality of heat-dissipating channels are provided in the high-voltage winding; for each of the plurality of heat-dissipating channels, and an upper end cross section of the heat-dissipating channel is greater than a lower end cross section of the heat-dissipating channel.

[0016] In an exemplary embodiment, each of the plurality of heat-dissipating channels includes an upper hole portion and a lower hole portion, and a width of the upper hole portion is greater than a width of the lower hole portion.

[0017] In an exemplary embodiment, two fans are provided below one winding unit, and the dry-type transformer includes at least three winding units arranged in parallels.

[0018] The features and advantages of the present application include: the support strips play supporting roles for the low-voltage winding body, ensuring support strength; channels for airflow are formed between the support strips, and the first grooves on the support strips also allow airflow channel, facilitating airflow within the low-voltage winding body to carry away heat. Moreover, by providing the first grooves, a contact area between the support strips and the low-voltage winding body surface is reduced, thereby increasing the heat dissipation area; first grooves are distributed at intervals, disrupting a boundary layer of the airflow, thus enhancing turbulence and reducing the boundary layer thickness, which is beneficial for utilizing continuous airflow disturbance to increase turbulence for enhanced heat transfer, improving the heat dissipation capability of the low-voltage winding, thereby reducing the overall temperature rise of the low-voltage winding in the dry-type transformer and alleviating the technical problem of transformer failures due to insufficient heat dissipation capability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 

FIG. 1 is a top view of a winding unit in a dry-type transformer according to an embodiment of the present application.

FIG. 2 is a front view of the winding unit (without a low-voltage winding) in the dry-type transformer according to an embodiment of the present application.

FIG. 3 is a top view of the low-voltage winding in the winding unit shown in FIG. 1.

FIG. 4 is a partial sectional view along A-A direction shown in FIG. 3.

FIG. 5 is an airflow diagram of the low-voltage winding shown in FIG. 4.

FIG. 6 is a partial sectional view along B-B direction shown in FIG. 3.

FIG. 7 is a top view of a support strip in the dry-type transformer according to an embodiment of the present application.

FIG. 8 is a front view of FIG. 7.

FIG. 9 is a left view of FIG. 7.

FIG. 10 is a partial sectional view of the low-voltage winding, high-voltage winding, and an insulation cylinder in the dry-type transformer according to an embodiment of the present application.

FIG. 11 is a front view of the insulation cylinder in the dry-type transformer according to an embodiment of the present application.

FIG. 12 is a front view of a vortex generator in the insulation cylinder shown in FIG. 10.

FIG. 13 is a structural diagram of a protrusion in the insulation cylinder shown in FIG. 10.

FIG. 14 is a left view of FIG. 13.

FIG. 15 is a top view of the high-voltage winding in the winding unit shown in FIG. 1.

FIG. 16 is a vertical partial sectional view of the high-voltage winding in the dry-type transformer according to an embodiment of the present application.

FIG. 17 is a structural diagram of an embodiment of a channel plate of a heat-dissipating channel in the high-voltage winding shown in FIG. 15.

FIG. 18 is a structural diagram of another embodiment of the channel plate of the heat-dissipating channel in the high-voltage winding shown in FIG. 15.

FIG. 19 is a front view of the dry-type transformer according to an embodiment of the present application.

FIG. 20 is a top view of the winding unit in the dry-type transformer shown in FIG. 19.

FIG. 21 is a left view of FIG. 19.

FIG. 22 is a top view of a support frame in the dry-type transformer shown in FIG. 19.

[0020] Explanation of main element symbols: 10 - winding unit; 20 - low-voltage winding; 21 - low-voltage winding body; 30 - support strip; 31 - first supporting portion; 32 - second supporting portion; 301 - first groove; 302 - second groove; 331 - width direction; 332 - inner-outer direction; 40 - insulating cylinder; 41 - protrusion; 42 - flow guide channel; 43 - vortex generator; 50 - high-voltage winding; 51 - heat-dissipating channel; 511 - upper hole portion; 512 - lower hole portion; 52 - channel plate; 60 - support frame; 61 - upper pad; 62 - lower pad; 71 - fan; 72 - iron core; 80 - base body.

DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of them. All other embodiments obtained by those skilled in the art without creative work based on the embodiments of the present application shall fall within the protection scope of the present application.

[0022] The present application provides a dry-type transformer. As shown in FIGS. 1-2 and FIGS. 19-21, the dry-type transformer may include: a base body (80), an iron core (72), a winding unit (10), and a fan (71). The winding unit (10) and the fan (71) are mounted on the base body (80). The winding unit (10) includes a high-voltage winding (50), an insulation cylinder (40), and a low-voltage winding (20) which are sequentially nested from outside to inside. The low-voltage winding (20) includes a low-voltage winding body (21) and a plurality of support strips (30). As shown in FIGS. 3-4, the low-voltage winding body (21) may be cylindrical, the plurality of support strips (30) are arranged in the low-voltage winding body (21), and the plurality of support strips (30) are distributed at intervals; a plurality of first grooves (301) are provided on a side wall of the support strip (30) and distributed at intervals along a longitudinal direction of the side wall.

[0023] The support strips (30) can provide support for the low-voltage winding body (21), ensuring support strength. Air channels are formed between the support strips (30), and the first grooves (301) on the support strips (30) also allow air to flow through, facilitating airflow within the low-voltage winding body (21) to carry away heat. Furthermore, by providing the first grooves (301), a contact area between the support strips (30) and the low-voltage winding body (21) surface can be reduced, thereby increasing the heat dissipation area. The plurality of first grooves (301) distributed at intervals disrupt a boundary layer of the airflow, thus enhancing turbulence and reducing the boundary layer thickness, which is beneficial for utilizing continuous airflow disturbance to increase turbulence for enhanced heat transfer, improving the heat dissipation capability of the low-voltage winding (20), thereby reducing the overall temperature rise of the low-voltage winding (20) in the dry-type transformer.

[0024] The low-voltage winding (20) can be a low-voltage foil-type winding. For the low-voltage foil-type winding, electromagnetic forces are generated during transformer operation or sudden short circuits. The electromagnetic forces during short circuits can reach hundreds of times that of rated operation, and the low-voltage foil-type winding is susceptible to deformation under pressure. Support strips of the low-voltage foil-type winding are placed in low-voltage winding channels, with a plurality of support strips distributed within the channels, serving as separation and support.

[0025] In conventional dry-type transformers, support strip structures generally adopt rectangular support strips, I-shaped support strips, etc., a plurality of support strips is evenly distributed in the channels. Although these support strip structures are simple and easy to manufacture, the support strips directly contact a surface of the low-voltage winding, resulting in poor heat dissipation at contact points. Meanwhile, the support strips divide the channel into several small channels. Due to transformer structural limitations, fans are generally installed at bottom sides of transformer, causing airflow to enter only through few small channels near the fans, unable to spread throughout the entire low-voltage winding channel. This greatly reduces the heat dissipation effect of the low-voltage winding.

[0026] Considering the structural characteristics of low-voltage foil-type windings, to enhance the heat dissipation capability of the low-voltage winding (20). In one embodiment of the present application, each support strip (30) includes first supporting portions (31) and second supporting portions (32) which are alternately distributed. As shown in FIG. 4-9, a cross section of the first supporting portion (31) differs from a cross section of the second supporting portion (32), and the first groove (301) is located on an outer side of the first supporting portion (31). Due to a shape change between the first supporting portion (31) and second supporting portion (32) and their alternate distribution, the side wall of the support strip (30) forms a concave-convex shape, and the concave parts of the side wall of the support strip (30) constituting the first grooves (301).

[0027] Furthermore, a width of the first supporting portion (31) is smaller than a width of the second supporting portion (32). As shown in FIGS. 3 and 7-8, the low-voltage winding (20) may be annular shape, a cross section of the low-voltage winding (20) may be elongated circular shape. The support strips (30) are distributed along a circumferential direction of the low-voltage winding (20) (the circumferential direction can be a surrounding direction), a width direction (331) of the support strips (30) corresponds to the circumferential direction of the low-voltage winding (20). That is, the greater the width of the first supporting portion (31) or the second supporting portion (32), the larger the dimension the first supporting portion (31) or second supporting portion (32) occupies in the circumferential direction of the low-voltage winding (20). For one support strip (30), because of the width of the first supporting portion (31) is smaller than the width of the second supporting portion (32), first grooves (301) are formed on the outer side of the first supporting portion (31), one first groove (301) is located between two second supporting portions (32).

[0028] As shown in FIGS. 7-9, a thickness of the first supporting portion (31) in an inner-outer direction (332) is greater than a thickness of the second supporting portion (32) in the inner-outer direction (332). The low-voltage winding (20) is annular, the thickness of the support strip (30) corresponds to the inner-outer direction (332) of the low-voltage winding (20). That is, the larger the dimension of the first supporting portion (31) or the second supporting portion (32) in the inner-outer direction (332), the greater the thickness of the support strip. As shown in FIGS. 6 and 9, because of the thickness of the first supporting portion (31) in the inner-outer direction (332) is greater than the thickness of the second supporting portion (32) in the inner-outer direction (332), second grooves (302) are formed on an outer side of the second supporting portion (32), one second groove (302) is located between two first supporting portions (31). Airflow can flow circumferentially through the second grooves (302), promoting airflow communication among a plurality air channels of circumferentially distributed.

[0029] As shown in FIGS. 3-6, the first grooves (301) and the second grooves (302) reduce the contact area between the support strips (30) and a surface of the low-voltage winding body (21), increasing the heat dissipation area. The first grooves (301) and second grooves (302) disrupt the fluid boundary layer, thus enhancing turbulence and reducing the boundary layer thickness, utilizing continuous fluid disturbance to increase turbulence for enhanced heat transfer. The air channels are interconnected, and during forced air cooling, the air from the fan (71) enters through one or more channels near the fan (71), the airflow can move circumferentially through the second grooves (302), enabling airflow distribution throughout all channels of the low-voltage winding (20), achieving full coverage and uniform heat dissipation within the entire channels of the low-voltage winding (20), thereby reducing overall temperature rise of the low-voltage winding (20).

[0030] Furthermore, both upper and lower ends of the support strip (30) are first supporting portions (31). As shown in FIGS. 4-5 and 8-9, since first grooves (301) are provided on the outer side of the second supporting portions (32), spacings between support strips (30) is larger at both upper and lower ends, which enlarges the air inlet and outlet of the channels, reducing the inlet resistance for air entering the channels. This allows more airflow to enter the channels, enhancing heat dissipation capability.

[0031] In one embodiment, the cross sections of the first supporting portion (31) and the second supporting portion (32) are rectangular, which is beneficial for utilizing the support strips (30) to enhance heat dissipation effect within the channels. Exemplarily, at the same height, the first supporting portions (31) of circumferentially distributed support strips (30) are aligned with each other, and the second supporting portions (32) of circumferentially distributed support strips (30) are aligned with each other, facilitating airflow within channels and airflow between channels, ensuring heat dissipation effect.

[0032] In one embodiment, a plurality of protrusions (41) are provided on the inner wall of the insulation cylinder (40), and/or the plurality of protrusions (41) are provided on the outer wall of the insulation cylinder (40). As shown in FIGS. 2 and 10, the low-voltage winding (20) and the high-voltage winding (50) are separated by the insulation cylinder (40), forming airflow channels between the low-voltage winding (20) and the insulation cylinder (40), and between the insulation cylinder (40) and the high-voltage winding (50). The protrusions (41) can disturb the airflow, and further break and thinn the boundary layer through disturbing the airflow, thus increasing heat transfer coefficient of local surface, and enhancing heat transfer effect. Exemplarily, a plurality of protrusions (41) can be provided on both inner and outer walls of the insulation cylinder (40).

[0033] As dry-type transformer designs become increasingly compact, the channels between the low-voltage winding (20) and the high-voltage winding (50) become smaller, and the electrical insulation distance between the low-voltage winding (20) and the high-voltage winding (50) correspondingly decreases. Adding the insulation cylinder (40) in the air channels, the insulation cylinder (40) may be made of epoxy board, the insulation cylinder (40) can prevent high voltage breakdown of the low-voltage winding (20), and further serve a heat dissipation separation function.

[0034] Furthermore, at least two protrusions (41) are arranged in groups. For two protrusions (41) arranged in groups, the distance between upper ends of the two protrusions is smaller than the distance between lower ends of the two protrusions. As shown in FIGS. 11 and 12, the two protrusions (41) arranged in groups form a "

" shape. When airflow moves from bottom to top, the grouped protrusions (41) jointly disturb the airflow, generating wing-tip vortices, which is beneficial for the airflow to carry away heat. Exemplarily, the two protrusions (41) arranged in groups are symmetrically distributed.

[0035] As shown in FIG. 11, the two protrusions (41) arranged in groups form a vortex generator (43), and a plurality of vortex generators (43) are arranged at intervals in the up-down direction. Furthermore, a flow guide channel (42) is provided between the upper ends of the two protrusions (41) arranged in groups, and the flow guide channels (42) of the plurality of vortex generators (43) arranged at intervals in the up-down direction are aligned with each other. The airflow moves from bottom to top, and passes upward through the flow guide channels (42) and channels between adjacent vortex generators (43), the airflow is disturbed by each vortex generator (43). When the airflow passes through the vortex generators (43), wing-tip vortices are generated, breaking and thinning the boundary layer, increasing heat transfer coefficient of local surface, enhancing heat transfer capability, and efficiently carrying away heat. The flow guide channels (42) of the vortex generators (43) in the same row are aligned, thus the flow guide channels (42) of the vortex generators (43) in the same row are on the same vertical line, which is beneficial for airflow movement to carry away heat.

[0036] Exemplarily, as shown in FIGS. 13 and 14, the protrusions (41) are airfoil-shaped, and the plurality of protrusions (41) are evenly distributed in a "

" shape on the outer wall of the insulation cylinder (40).

[0037] The insulation cylinder (40) is placed in the main channel between the low-voltage winding (20) and the high-voltage winding (50). The protrusions (41) on the insulation cylinder (40) can be formed in various ways, for example: through mechanical processing; or directly formed by molds during injection molding of the insulation cylinder (40). In one embodiment, the protrusions (41) and the insulation cylinder (40) are formed separately, and the protrusions (41) and the insulation cylinder (40) are connected together by drilling small holes in the insulation cylinder (40) and inserting the processed protrusions (41) into the insulation cylinder (40) with an interference fit.

[0038] Furthermore, as shown in FIG. 2, the insulation cylinder (40) is extended so that the upper end of the insulation cylinder (40) exceeds the height of both the low-voltage winding (20) and the high-voltage winding (50). A height difference utilizes the "chimney effect" to enhance ventilation and heat exchange, increasing airflow volume in the air channels and thereby improving natural convection heat transfer.

[0039] The high-voltage winding (50) is provided with a plurality of heat-dissipating channels (51). For cast high-voltage windings (50) cast with epoxy resin, several channel plates (52) are inserted into the high-voltage winding (50) channels and cast together. After casting, the channel plates (52) are removed through demolding, ultimately forming individual heat-dissipating channels (51). In conventional high-voltage windings (50), rectangular channel plates (52) are used for easy manufacturing and demolding.

[0040] The applicant discovered that the temperature field in operating dry-type transformers is not uniform from top to bottom. The upper portion of the high-voltage winding (50) is the highest temperature zone, the temperature in this area is the highest, so this area is a weak part of the insulating material, and inadequate heat dissipation can easily damage the insulating performance, leading to damage the transformer. However, straight rectangular channels cannot effectively reduce the temperature at highest temperature spots.

[0041] The applicant has improved the heat-dissipating channels (51).

[0042] In one embodiment, the upper end cross section of the heat-dissipating channel (51) is larger than the lower end cross section of the heat-dissipating channel (51). Considering that the upper portion of the high-voltage winding (50) is the highest temperature zone and the weak point of insulation material, enlarging the channel opening at the upper end of the heat-dissipating channel (51) can effectively increase the heat dissipation area at the highest temperature spots, meanwhile maintaining the middle and lower portions unchanged, without compromising the structural strength of the high-voltage winding (50).

[0043] When manufacturing the high-voltage winding (50), as shown in FIG. 16, channel plates (52) are evenly placed in the channels of the high-voltage winding (50) cast with epoxy resin. The channel plate 52 is a paddle-board structure, which is wider at the upper end and narrower at the lower end, and a circular hole is provided at the upper end. The channel plates (52) are cast together with the high-voltage winding (50), and after demolding through the circular holes at the upper end of the channel plates (52), heat-dissipating channels (51) are formed where the channel plates (52) were located. The arrows shwon in FIG. 16 indicate airflow direction, and for illustration purposes, some heat-dissipating channels (51) show the channel plates (52) while others omit the channel plates (52). As shown in FIG. 15, a plurality of heat-dissipating channels (51) are distributed in a circular. At an arc-shaped part of the high-voltage winding (50), the heat-dissipating channels (51) are also correspondingly in arc shapes. FIG. 17 illustrates the channel plate (52) for forming arc-shaped heat-dissipating channels (51). FIG. 18 illustrates the channel plate (52) for forming straight heat-dissipating channels (51).

[0044] As shown in FIG. 16, the heat-dissipating channel (51) includes an upper hole portion (511) and a lower hole portion (512), a width of the upper hole portion (511) is greater than a width of the lower hole portion (512). The high-voltage winding (50) is circular as shown in FIG. 15, the heat-dissipating channels (51) are distributed along a circumferential direction of the high-voltage winding (50). The width direction (331) of the heat-dissipating channels (51) corresponds to the circumferential direction of the high-voltage winding (50), meaning the greater the width of the upper hole portion (511) or the lower hole portion (512), the larger the dimension the upper hole portion (511) or the lower hole portion (512) occupies in the circumferential direction of the high-voltage winding (50). For one heat-dissipating channel (51), the width of the upper hole portion (511) is greater than the width of the lower hole portion (512), meaning the upper end of the heat-dissipating channel (51) is larger than the lower end of the heat-dissipating channel (51), effectively increasing the heat dissipation area at the highest temperature spots by enlarging the channel opening at the upper end of the heat-dissipating channel (51). Exemplarily, there is an arc-shaped transition between the upper hole portion (511) and the lower hole portion (512).

[0045] In one embodiment, as shown in FIGS. 19-21, two fans (71) are provided below one winding unit (10), and the dry-type transformer includes at least three winding units (10) arranged in parallel. The airflow provided by the fans (71) flows bottom to top into the low-voltage winding (20), the high-voltage winding (50), and the channel between the low-voltage winding (20) and the high-voltage winding (50), to cool the low-voltage winding (20) and the high-voltage winding (50). Exemplarily, as shown in FIG. 21, the fans (71) are installed on two sides at the bottom of the high-voltage winding (50). The winding unit (10) is sleeved on an outside of a core column between two iron cores (72). As shown in FIGS. 1-2 and 19-22, the winding unit (10) includes a support frame (60) mounted on the base body (80) to support the winding unit (10). The support frame (60) includes four upper pads (61) and four lower pads (62), grooves are provided in both upper pads (61) and lower pads (62) for fixing the insulation cylinder (40) and supporting the winding unit (10).

[0046] The dry-type transformer provided by the present application enhances heat dissipation capability through improved internal structure design and enhanced heat transfer, without changing the original mechanical structural strength, external environmental conditions, and adding additional heat-dissipating devices. This results in operating temperature rises approximately 5-10°C lower than conventional dry-type transformers, improving the overall heat dissipation capability of epoxy resin-type dry-type transformers.

[0047] The above description only represents several embodiments of the present application. Those skilled in the art can make various modifications or variations to the embodiments of the present application based on the disclosed content without departing from the spirit and scope of the present application.

Claims

1. A dry-type transformer, characterized in that, the dry-type transformer comprises a base body, an iron core, a winding unit, and a fan, the winding unit and the fan are mounted on the base body, the winding unit comprises a high-voltage winding, an insulation cylinder, and a low-voltage winding which are sequentially nested from outside to inside;

the low-voltage winding comprises a low-voltage winding body and a plurality of support strips, the low-voltage winding body is cylindrical, the plurality of support strips are arranged in the low-voltage winding body, and the plurality of support strips are distributed at intervals; a plurality of first grooves are provided on a side wall of each of the plurality of support strips, and the plurality of first grooves are distributed at intervals along a longitudinal direction of the side wall;

a plurality of protrusions are provided on an inner wall of the insulation cylinder, and/or the plurality of protrusions are provided on an outer wall of the insulation cylinder;

at least two protrusions are arranged in groups; and

for two protrusions arranged in groups, a distance between upper ends of the two protrusions is smaller than a distance between lower ends of the two protrusions.

2. The dry-type transformer as claimed in claim 1, characterized in that, each of the plurality of support strips comprises first supporting portions and second supporting portions which are alternately distributed, a cross section of the first supporting portion is different from a cross section of the second supporting portion, and the first groove is located on an outer side of the first supporting portion.

3. The dry-type transformer as claimed in claim 2, characterized in that, a width of the first supporting portion is smaller than a width of the second supporting portion.

4. The dry-type transformer as claimed in claim 3, characterized in that, a thickness of the first supporting portion in an inner-outer direction is greater than a thickness of the second supporting portion in the inner-outer direction.

5. The dry-type transformer as claimed in any one of claim 3, characterized in that, an upper end and a lower end of each of the plurality of support strips are formed two first supporting portions.

6. The dry-type transformer as claimed in claim 3, characterized in that, cross sections of the first supporting portion and the second supporting portion are both rectangular.

7. The dry-type transformer as claimed in claim 1, characterized in that, the two protrusions arranged in groups form a vortex generator, and a plurality of vortex generators are arranged at intervals in an up-down direction.

8. The dry-type transformer as claimed in claim 7, characterized in that, a flow guide channel is provided between the upper ends of the two protrusions arranged in groups, and the flow guide channels of the plurality of vortex generators arranged at intervals in the up-down direction are aligned with each other.

9. The dry-type transformer as claimed in any one of claims 1-6, characterized in that, a plurality of heat-dissipating channels are provided in the high-voltage winding; for each of the plurality of heat-dissipating channels, and an upper end cross section of the heat-dissipating channel is greater than a lower end cross section of the heat-dissipating channel.

10. The dry-type transformer as claimed in claim 9, characterized in that, each of the plurality of heat-dissipating channels comprises an upper hole portion and a lower hole portion, and a width of the upper hole portion is greater than a width of the lower hole portion.

11. The dry-type transformer as claimed in claim 1, characterized in that, two fans are provided below one winding unit, and the dry-type transformer comprises at least three winding units arranged in parallels.

Drawing