CN111816417A - Oil-immersed transformer and manufacturing method thereof - Google Patents

Abstract

The invention provides an oil-immersed transformer and a manufacturing method thereof. The oil-immersed transformer includes: a transformer body; the oil tank, the oil tank has the inner chamber, and it has transformer oil to fill in the inner chamber, and the transformer main part sets up in the inner chamber to in immersing transformer oil, the oil tank includes: the oil tank comprises an oil tank main body, wherein a pressure relief opening and a reinforcing rib are arranged on the oil tank main body; the protective structure is fixedly arranged on the oil tank main body and seals the pressure relief opening, and the fracture threshold of the protective structure is smaller than that of the oil tank main body; the protection casing, protection casing cover are established outside protective structure to enclose into the extension chamber with the cooperation of oil tank main part, when protective structure seals the pressure release opening, the extension chamber is kept apart with the inner chamber, and the strengthening rib is located the extension intracavity. The oil-immersed transformer has better explosion-proof performance.

Description

Oil-immersed transformer and manufacturing method thereof

Technical Field

The embodiment of the application relates to the field of transformers, in particular to an oil-immersed transformer and a manufacturing method thereof.

Background

Transformers can be classified into oil-immersed transformers, dry-type transformers, and the like according to different insulation modes. The oil-immersed transformer mainly comprises an iron core, a winding, an oil tank, a tap switch and the like. The oil tank is filled with transformer oil, the iron core, the winding and the tap switch are arranged in the oil tank, the iron core and the winding are immersed in the transformer oil, and the transformer oil plays roles of insulation and cooling. Tap changers may be used to regulate the output voltage of the transformer.

The existing transformer can generate a large amount of gas when arcing is generated in the working process, so that the local pressure in an oil tank of the transformer rises suddenly, if the space for arcing is small, the oil pressure in the space can rise suddenly in a short time and cannot be transferred into a large-volume space, so that the area corresponding to the space for arcing in the oil tank can bear huge expansive force to generate damage, and oil gas leakage is caused. If the temperature in this area is high or an arc is still present, an explosion can easily occur. Therefore, an oil tank with higher safety is needed to improve the safety of the oil-immersed transformer.

Disclosure of Invention

In order to solve the above problem, embodiments of the present application provide an oil-immersed transformer and a manufacturing method thereof, so as to at least partially solve the above problem.

According to a first aspect of embodiments of the present application, there is provided an oil-filled transformer, comprising: a transformer body; the oil tank, the oil tank has the inner chamber, and it has transformer oil to fill in the inner chamber, and the transformer main part sets up in the inner chamber to in immersing transformer oil, the oil tank includes: the oil tank comprises an oil tank main body, wherein a pressure relief opening and a reinforcing rib are arranged on the oil tank main body; the protective structure is fixedly arranged on the oil tank main body and seals the pressure relief opening, and the fracture threshold of the protective structure is smaller than that of the oil tank main body; the protection casing, the protection casing cover is established outside protective structure to enclose into the extension chamber with the cooperation of oil tank main part, when protective structure seals the pressure release opening, extension chamber and inner chamber are kept apart, and the strengthening rib is located the extension intracavity.

Optionally, the protective structure comprises a protective cover and a fastener, the fastener secures the protective cover to the fuel tank body and the protective cover closes the pressure relief opening, and a rupture threshold of at least one of the fastener and the protective cover is less than a rupture threshold of the fuel tank body.

Optionally, the fastener includes a first fastening bolt, the fuel tank main body is provided with a plurality of mounting holes, the first fastening bolt corresponds to the mounting holes one to one, the first fastening bolt penetrates through the protective cover plate and is matched with the corresponding mounting hole to fix the protective cover plate on the fuel tank main body, and the sum of the fracture threshold values of the first fastening bolts is smaller than that of the fuel tank main body.

Optionally, the oil-filled transformer further includes a tap switch disposed in the inner cavity of the oil tank, the pressure relief opening is disposed on the first sidewall of the oil tank main body, and a projection of the tap switch on the first sidewall covers at least a portion of the pressure relief opening.

Optionally, the tank body further comprises a top cover, a second fastening bolt is connected between the tap changer and the top cover, and the fracture threshold of the protective structure is smaller than that of the second fastening bolt.

Optionally, the tank main body further includes a second sidewall and a third sidewall, the second sidewall and the third sidewall are parallel to each other and spaced apart from each other, the first sidewall is connected between the second sidewall and the third sidewall, and the protective cover includes: the first protective side wall is fixedly connected with the second side wall, the oil tank main body further comprises a first reinforcing protrusion, one part of the first reinforcing protrusion is fixedly arranged on the second side wall, and the other part of the first reinforcing protrusion is fixedly arranged on the first protective side wall; the second protection lateral wall, second protection lateral wall and third lateral wall fixed connection, the oil tank main part still includes that the second strengthens protruding, and protruding partly fixed setting is strengthened on the third lateral wall to the second, and the protruding other part of second enhancement is fixed to be set up on the second protection lateral wall.

Optionally, the first reinforcing protrusion is provided with a first buffer groove, and an opening of the first buffer groove faces to a connecting position of the second side wall and the first protective side wall; and/or a second buffer groove is arranged on the second reinforcing protrusion, and the opening of the second buffer groove faces the connecting position of the third side wall and the second protective side wall.

Optionally, the expansion chamber is a vacuum chamber, or the expansion chamber is filled with a flame retardant gas.

Optionally, a solid packing layer for solidifying and cooling the oil gas is arranged in the expansion cavity.

According to another aspect of the present invention, there is provided a method for manufacturing an oil-filled transformer, the method comprising: a pressure relief opening is formed in a tank main body of the oil tank; fixing the protective structure on the oil tank main body, and enabling the protective structure to seal the pressure relief opening; the protective cover is fixedly connected outside the oil tank main body, is covered outside the protective structure and is matched with the oil tank main body to form an expansion cavity.

According to this application embodiment provide the oil tank be used for installing and protecting transformer main part, transformer main part immerses in the transformer oil to carry out insulation protection through the transformer oil. Through set up the protective structure that the threshold value of breaing is less than the threshold value of breaing of oil tank main part on the oil tank main part for when the oil tank main part received great pressure, protective structure becomes the weak position on the oil tank main part, can appear damaging and breaking at first. Because protective structure has covered the pressure release opening in the oil tank main part again, consequently can open the pressure release opening after protective structure damages and breaks for oil gas in the oil tank main part can discharge outside the oil tank main part through the pressure release opening, thereby realizes the pressure release, with the pressure in the quick reduction oil tank main part, thereby protects the transformer main part in the oil tank main part. And because the protective cover is arranged outside the oil tank main body and covers the protective structure, the protective cover realizes the isolation of the inner cavity of the oil tank from the external environment, and ensures that oil gas in the inner cavity of the oil tank can be discharged into an expansion cavity formed by the protective cover after the pressure relief opening is opened, thereby releasing pressure and ensuring that the oil gas cannot be contacted with the external air, thereby avoiding fire hazard. Through set up the strengthening rib in the oil tank main part, and because the strengthening rib is located the extension intracavity, that is to say the strengthening rib is close to the pressure release opening and sets up for the strengthening rib can strengthen the structural strength of oil tank main part, promotes the threshold value of breaking, avoids setting up the adverse effect of pressure release opening to the structural strength of oil tank main part.

Drawings

The drawings are only for purposes of illustrating and explaining the present application and are not to be construed as limiting the scope of the present application. Wherein the content of the first and second substances,

fig. 1 shows a perspective view of a first viewing angle of an oil filled transformer according to an embodiment of the application;

fig. 2 shows a schematic partial cross-sectional structural view at a protective cover of an oil filled transformer according to an embodiment of the application;

fig. 3 shows a schematic partial exploded sectional view at a protective cover of an oil filled transformer according to an embodiment of the application;

fig. 4 shows a schematic partial cross-sectional view at a tap changer of an oil filled transformer according to an embodiment of the application;

FIG. 5 shows a partial enlarged view at I in FIG. 4;

fig. 6 shows a partial perspective view of a second viewing angle of an oil filled transformer according to an embodiment of the application.

Description of reference numerals:

10. an oil tank;

111. a pressure relief opening;

112. a first side wall;

113. a top cover;

114. a second side wall;

115. a third side wall;

116. a first reinforcing protrusion;

116a, a first buffer groove;

117. a second reinforcing protrusion;

117a, a second buffer groove;

12. a protective structure;

13. a protective cover;

131. a first protective sidewall;

132. a second protective sidewall;

20. a tap changer.

Detailed Description

In order to more clearly understand the technical features, objects and effects of the embodiments of the present application, specific embodiments of the present application will be described with reference to the accompanying drawings.

Referring to fig. 1 to 6, an oil-immersed transformer according to an embodiment of the present disclosure includes a transformer main body and an oil tank 10, where the oil tank 10 has an inner cavity filled with transformer oil, the transformer main body is disposed in the inner cavity and immersed in the transformer oil, the oil tank 10 includes an oil tank main body, a protective structure 12 and a protective cover 13, and the oil tank main body is provided with a pressure relief opening 111 and a reinforcing rib; the protective structure 12 is fixedly arranged on the oil tank main body, the protective structure 12 seals the pressure relief opening 111, and the fracture threshold of the protective structure 12 is smaller than that of the oil tank main body; the protection casing 13 covers the protection structure 12 and is matched with the oil tank main body to form an expansion cavity, when the protection structure 12 seals the pressure relief opening 111, the expansion cavity is isolated from the inner cavity, and the reinforcing ribs are located in the expansion cavity.

In the present embodiment, the oil tank 10 is used to mount and protect a transformer body, which is immersed in transformer oil for insulation protection by the transformer oil. By providing the protective structure 12 on the fuel tank main body, which has a rupture threshold smaller than that of the fuel tank main body, when the fuel tank main body is subjected to a large pressure, the protective structure 12 becomes a weak point on the fuel tank main body, and damage and rupture may occur first. Because protective structure 12 has covered pressure release opening 111 on the oil tank main part again, consequently can open pressure release opening 111 after protective structure 12 damages and breaks for oil gas in the oil tank main part can be discharged outside the oil tank main part through pressure release opening 111, thereby realizes the pressure release, with the pressure in the quick reduction oil tank main part, thereby protects the transformer main part in the oil tank main part. And because the protective cover 13 is also arranged outside the oil tank main body, and the protective cover 13 covers the protective structure 12, the protective cover 13 realizes the isolation of the inner cavity of the oil tank 10 from the external environment, and ensures that oil gas in the inner cavity of the oil tank 10 can be discharged into an expansion cavity formed by the protective cover 13 after the pressure relief opening 111 is opened, thereby releasing pressure, ensuring that the oil gas cannot be contacted with the external air, and avoiding fire. Through set up the strengthening rib in the oil tank main part, and because the strengthening rib is located the extension intracavity, that is to say the strengthening rib is close to pressure release opening 111 and sets up for the strengthening rib can strengthen the structural strength of oil tank main part, promotes the threshold value of breaking, avoids setting up the adverse effect of pressure release opening 111 to the structural strength of oil tank main part.

In the present embodiment, the transformer main body includes a core, a winding, and the like. Of course, the transformer body may also include other suitable structures as desired.

Optionally, in order to ensure the protection capability and reduce the production cost and the difficulty of manufacturing and production, the protection structure 12 includes a protection cover plate and a fastener, the fastener fixes the protection cover plate on the fuel tank main body, and the protection cover plate closes the pressure relief opening 111, and a fracture threshold of at least one of the fastener and the protection cover plate is smaller than that of the fuel tank main body. The protective structure is simple, the production cost is low, the protective cover plate can be conveniently fixed on the oil tank main body, the assembly difficulty is low, and the fracture threshold value of the protective structure is easy to control.

Wherein the rupture threshold of the protective structure may be a force required for the protective structure to rupture. In order to make protective structure's the rupture threshold value be less than the rupture threshold value of oil tank main part to protective structure still has certain structural strength and can satisfy the intensity demand when oil-immersed transformer moves, seals pressure release opening 111 through the protective cover board, thereby guarantees that oil-immersed transformer can not produce transformer oil leakage in the normal course of operation, and the fastener can be fixed protective cover board reliably in the oil tank main part, guarantees protective cover board and oil tank main part's joint strength.

The shape, size, material, etc. of the protective cover plate may be determined according to the requirement, which is not limited in this embodiment. For example, the protective cover may be a steel plate, the thickness of which is more determined by the structural strength requirements. The shape of the protective cover plate may be the same as or different from the shape of the pressure relief opening 111 as long as it is ensured that the pressure relief opening 111 can be closed.

Optionally, the fastener includes a first fastening bolt, the fuel tank main body is provided with a plurality of mounting holes, the first fastening bolt corresponds to the mounting holes one to one, the first fastening bolt penetrates through the protective cover plate and is matched with the corresponding mounting hole to fix the protective cover plate on the fuel tank main body, and the sum of the fracture threshold values of the first fastening bolts is smaller than that of the fuel tank main body. The protective cover plate is fixed through the first fastening bolt, so that on one hand, the installation is convenient, and the structure is simple; on the other hand, the fracture threshold of the protective structure can be changed by adjusting the number of the first fastening bolts and the diameters of the first fastening bolts, so that the fracture threshold of the protective structure is easier to control and adjust.

Of course, in other embodiments, the fastening member may be other suitable components capable of fixing the protective cover to the fuel tank main body, and the embodiment is not limited thereto.

Optionally, the oil filled transformer further comprises a tap switch 20, the tap switch 20 is disposed in an inner cavity of the oil tank 10, the pressure relief opening 111 is disposed on a first sidewall 112 of the oil tank body, and a projection of the tap switch 20 on the first sidewall 112 covers at least a portion of the pressure relief opening 111. Since most of arcing of the oil-immersed transformer is caused by the tap changer 20, that is, oil gas is more easily generated by transformer oil at the tap changer 20, so that the pressure at the tap changer 20 suddenly rises, in order to protect the tap changer 20, the protective structure 12 is arranged at a position close to the tap changer 20, so that when the pressure at the tap changer 20 suddenly rises, the protective structure 12 is firstly broken, the pressure relief opening 111 is opened to release the pressure, thereby preventing the position of the oil tank body where the tap changer 20 is installed from being broken due to excessive pressure, realizing that the breaking position of the oil tank 10 is controllable, and protecting important positions and important structures of the oil tank 10. In order to ensure that the shielding structure 12 is sufficiently close to the tap changer 20, the shielding structure 12 is arranged in a position where it is at least partly covered by the projection of the tap changer 20 on the first side wall 112.

In this embodiment, in order to ensure the safety of the oil-immersed transformer and ensure a good insulation effect, the oil tank main body further includes a top cover 113, a second fastening bolt is connected between the tap switch 20 and the top cover 113, and a fracture threshold of the protective structure 12 is smaller than that of the second fastening bolt. The tap changer 20 is arranged on the top cover 113 such that the tap changer 20 has a distance from the first side wall 112 of the tank body, in which distance transformer oil can be filled for insulation. In addition, the tap changer 20 is mounted on the top cover 113 by means of second fastening bolts, and in order to protect the tap changer 20, it is only necessary to make the breaking threshold of the protective structure 12 smaller than the breaking threshold of the second fastening bolts. For example, making the diameter of the first fastening bolt smaller than the diameter of the second fastening bolt in the protective structure 12, or making the number of the first fastening bolts smaller than the number of the second fastening bolts, etc., may make the fracture threshold of the protective structure 12 smaller than the fracture threshold of the second fastening bolt.

In order to still enable the inner chamber and the external environment of oil tank and keep apart after protective structure 12 appears damaged to prevent that oil gas from contacting the air and appearing the conflagration, be connected with protection casing 13 outside the oil tank main part, protection casing 13 encloses into the extension chamber with the cooperation of oil tank main part, in order to hold the oil gas that flows out from the inner chamber of oil tank 10, the too high pressure obtains releasing in the inner chamber that makes oil tank 10, guarantees again that it keeps apart with the external environment.

Optionally, to increase the pressure relief speed, the expansion chamber is a vacuum chamber. Thus, the protective structure 12 is separated from the oil tank main body after being broken, so that the pressure relief opening 111 is opened, and oil gas in the oil tank main body can rapidly flow into the expansion cavity due to the fact that the expansion cavity is a vacuum cavity, and pressure is rapidly released.

Optionally, the expansion chamber is filled with a flame retardant gas. Through filling flame retardant gas in the extension intracavity, can prevent that oil gas from burning because the electric arc effect, promote the security.

Or a solid filling layer for solidifying and cooling oil gas is arranged in the expansion cavity. The oil gas flowing into the expansion cavity can be rapidly cooled and solidified by arranging the solid filling layer, so that the safety is ensured. Of course, the expansion chamber may be filled with other suitable chemical agents in addition to the solid filler layer.

The structure, shape, size, etc. of the protection mask 13 may be determined as needed, and the embodiment is not limited thereto.

For example, in one possible mode, the tank body further comprises a second side wall 114 and a third side wall 115, the second side wall 114 and the third side wall 115 are parallel to each other and are arranged at a distance, the first side wall 112 is connected between the second side wall 114 and the third side wall 115, and the protection cover 13 comprises a first protection side wall 131 and a second protection side wall 132.

The first protective side wall 131 is fixedly connected to the second side wall 114, the tank main body further includes a first reinforcing protrusion 116, a portion of the first reinforcing protrusion 116 is fixedly disposed on the second side wall 114, and another portion of the first reinforcing protrusion 116 is fixedly disposed on the first protective side wall 131. The first protective side wall 131 and the second side wall 114 are connected to achieve the connection of the protective cover 13 to the tank main body. In order to enhance the structural strength of the shield 13 and the tank main body, first reinforcing protrusions 116 are provided on the second side wall 114 and the first shield side wall 131.

Similarly, the second protective sidewall 132 is fixedly connected to the third sidewall 115, and the tank main body further includes a second reinforcing protrusion 117, a portion of the second reinforcing protrusion 117 is fixedly disposed on the third sidewall 115, and another portion of the second reinforcing protrusion 117 is fixedly disposed on the second protective sidewall 132. The second protective side wall 132 is connected to the third side wall 115 to effect connection of the protective cover 13 to the tank body. In order to enhance the structural strength of the shield 13 and the tank main body, thereby enhancing the explosion-proof capability, second reinforcing protrusions 117 are provided on the third side wall 115 and the second shield side wall 132 to enhance the structural strength.

Optionally, in order to avoid stress concentration, the tank main body and the protective cover have certain deformability, so that part of energy is absorbed through deformation of the tank main body and the protective cover, the first reinforcing protrusion 116 is provided with a first buffer groove 116a, and an opening of the first buffer groove 116a faces to a connecting position of the second side wall 114 and the first protective side wall 131; and/or, a second buffer groove 117a is provided on the second reinforcing protrusion 117, and the opening of the second buffer groove 117a faces to the connecting position of the third side wall 115 and the second protective side wall 132.

The less protective structure 12 of threshold value is broken through setting up in the oil tank main part to the oil-immersed transformer of this embodiment for when producing the arcing and causing the sudden rise of partial pressure, protective structure 12 can break prior to the oil tank main part, thereby opens pressure release opening 111, makes oil gas can discharge fast through pressure release opening 111, realizes the quick release of pressure. The mode has not only guaranteed the safety of oil tank main part, and the thinking of this kind of solution problem is very novel moreover, is different from the solution of current improvement oil-immersed transformer's pressure release valve's response speed, also is different from the structural strength who promotes the at least partial key region of oil tank main part, guarantees not rupture under huge pressure not the scheme of revealing.

The idea of this embodiment is to provide a protective structure with a rupture threshold smaller than that of the tank body in some areas (such as tap openings, hand holes, etc.) with lower structural strength or any required areas of the tank body, so that the protective structure 12 becomes a weak point of the tank, and when a rupture occurs, the protective structure 12 will rupture first, so that a directional rupture is realized, and the loss is controlled within a preset range.

This kind of mode is compared in the scheme of traditional oil tank intensity reinforcing, because the embodiment of this application is the weak point of making on oil tank 10 voluntarily to increase the extension chamber, promote the volume that can release of oil gas and promote explosion-proof performance, the mode damage of the embodiment of this application is more controllable, and principle and theory are more advanced, and it is very difficult to have solved flange etc. on the current oil tank in addition and increase structural strength, and problem with high costs. The method of the embodiment has lower technical difficulty and lower cost.

Compared with the scheme of using a new pressure release valve, the mode of the embodiment of the application has stronger flexibility, the pressure release opening 111 and the protection structure 12 can be arranged at any required positions, and the area of the pressure release opening 111 of the pressure release opening of the pressure release valve can be larger, so that the pressure release opening 111 opened after the protection structure 12 is damaged is large enough, and the pressure in the oil tank main body can be reduced more quickly and effectively. In addition, the released oil gas enters the expansion cavity and is still isolated from the atmosphere, so that explosion can be avoided, and the safety is ensured.

The protection casing of this application embodiment set up position, size and shape all can suitably be adjusted as required, and protective structure's shape also can be adjusted as required to reinforcing flexibility.

According to another aspect of the present invention, there is provided a method for manufacturing an oil-filled transformer, the method comprising: a pressure relief opening 11 is formed in a tank main body of the tank 10; fixing the protective structure 12 on the oil tank main body, and enabling the protective structure 12 to seal the pressure relief opening 111; and a protective cover 13 is fixedly connected outside the oil tank main body, and the protective cover 13 is covered outside the protective structure 12 and matched with the oil tank main body to form an expansion cavity. The oil-immersed transformer with the pressure relief opening 111, the protection structure 12 and the protection cover 13 can be processed quickly and conveniently by the method, and when the local pressure inside the oil tank main body of the oil-immersed transformer is too high, the protection structure 12 can be damaged preferentially, so that the pressure relief opening 111 is opened to enable oil gas to enter the expansion cavity, the quick pressure relief of the oil tank main body is realized, and the safety of the oil tank 10 is improved. The manufacturing method has low processing difficulty and low production cost.

It should be understood that although the present description has been described in terms of various embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein may be combined as suitable to form other embodiments, as will be appreciated by those skilled in the art.

The above description is only an exemplary embodiment of the present disclosure, and is not intended to limit the scope of the present disclosure. Any person skilled in the art should be able to make equivalent changes, modifications and combinations without departing from the concept and principle of the embodiments of the present application.

Claims (10)

1. An oil-filled transformer, comprising:

a transformer body;

oil tank (10), oil tank (10) have the inner chamber, it has transformer oil to fill in the inner chamber, the transformer main part sets up in the inner chamber, and dip in the transformer oil, oil tank (10) include:

the oil tank comprises an oil tank main body, wherein a pressure relief opening (111) and reinforcing ribs are arranged on the oil tank main body;

the protective structure (12) is fixedly arranged on the oil tank main body, the protective structure (12) seals the pressure relief opening (111), and the fracture threshold of the protective structure (12) is smaller than that of the oil tank main body;

protection casing (13), protection casing (13) cover is established outside protective structure (12), and with the oil tank main part cooperation encloses into the extension chamber, protective structure (12) seal during pressure release opening (111), the extension chamber with the inner chamber is kept apart, just the strengthening rib is located the extension intracavity.

2. Oil filled transformer according to claim 1, characterized in that the protective structure (12) comprises a protective cover and a fastener, the fastener secures the protective cover on the tank body and the protective cover closes the pressure relief opening (111), the rupture threshold of at least one of the fastener and the protective cover being smaller than the rupture threshold of the tank body.

3. The oil-filled transformer of claim 2, wherein the fastening member comprises a first fastening bolt, a plurality of mounting holes are formed in the oil tank main body, the first fastening bolt corresponds to the mounting holes one by one, the first fastening bolt penetrates through the protective cover plate and is matched with the corresponding mounting holes to fix the protective cover plate on the oil tank main body, and the sum of fracture thresholds of the first fastening bolts is smaller than that of the oil tank main body.

4. Oil filled transformer according to any of claims 1-3, characterized in that it further comprises a tap changer (20), that the tap changer (20) is arranged in the inner cavity of the oil tank (10), that the pressure relief opening (111) is arranged on a first side wall (112) of the tank body, and that a projection of the tap changer (20) on the first side wall (112) covers at least part of the pressure relief opening (111).

5. Oil filled transformer according to claim 4, characterized in that the tank body further comprises a top cover (113), that a second fastening bolt is connected between the tap changer (20) and the top cover (113), and that the rupture threshold of the protective structure (12) is smaller than the rupture threshold of the second fastening bolt.

6. Oil filled transformer according to claim 4, characterized in that the tank body further comprises a second side wall (114) and a third side wall (115), the second side wall (114) and the third side wall (115) being parallel to each other and spaced apart, the first side wall (112) being connected between the second side wall (114) and the third side wall (115), the protective cover (13) comprising:

the first protective side wall (131) is fixedly connected with the second side wall (114), the oil tank main body further comprises a first reinforcing protrusion (116), one part of the first reinforcing protrusion (116) is fixedly arranged on the second side wall (114), and the other part of the first reinforcing protrusion (116) is fixedly arranged on the first protective side wall (131);

the oil tank main body further comprises a second reinforcing protrusion (117), one part of the second reinforcing protrusion (117) is fixedly arranged on the third side wall (115), and the other part of the second reinforcing protrusion (117) is fixedly arranged on the second protective side wall (132).

7. Oil filled transformer according to claim 6, characterized in that the first reinforcing protrusion (116) is provided with a first buffer groove (116a), and the opening of the first buffer groove (116a) faces the connection position of the second side wall (114) and the first protection side wall (131); and/or a second buffer groove (117a) is arranged on the second reinforcing protrusion (117), and the opening of the second buffer groove (117a) faces to the connecting position of the third side wall (115) and the second protection side wall (132).

8. The oil-filled transformer of claim 1, wherein the expansion cavity is a vacuum cavity, or the expansion cavity is filled with a flame retardant gas.

9. The oil filled transformer of claim 1, wherein the expansion cavity is provided with a solid packing layer that solidifies and cools oil and gas.

10. A manufacturing method of an oil-filled transformer, characterized in that the manufacturing method is used for manufacturing the oil-filled transformer according to any one of claims 1-9, and the manufacturing method comprises:

a pressure relief opening (11) is formed in a tank body of the tank (10);

fixing the protective structure (12) on the oil tank main body, and enabling the protective structure (12) to close the pressure relief opening (111);

the outer fixed connection of oil tank main part protection casing (13), and make protection casing (13) cover establish outside protective structure (12), and with the cooperation of oil tank main part encloses into the extension chamber.

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