Oil tank for oil-immersed transformer and oil-immersed transformer

Abstract

The utility model provides an oil tank for an oil-immersed transformer and the oil-immersed transformer, the oil tank comprises a main tank body and an auxiliary tank body, the main tank body defines a first accommodating space, and the first accommodating space is configured to accommodate and bear a transformer main body; a second containing space is limited by the auxiliary box body, the auxiliary box body has a folded form and an unfolded form, and the volume of the second containing space of the auxiliary box body in the folded form is smaller than that of the second containing space of the auxiliary box body in the unfolded form; wherein the first accommodating space of the main box body is communicated with the second accommodating space of the auxiliary box body so as to accommodate insulating oil together. Therefore, the auxiliary tank body can be switched between the folding form and the unfolding form, so that the internal volume of the oil tank is adjusted.

Description

Technical Field

[0001] The present application relates to the technical field of transformers, and in particular to an oil tank for an oil-immersed transformer and an oil-immersed transformer. Background Art

[0002] Transformers can be divided into dry-type transformers and oil-immersed transformers. Dry-type transformers are transformers whose core and windings are not immersed in insulating oil. Oil-immersed transformers mainly consist of an iron core, windings, an oil tank, an oil pillow, insulating bushings, a tap changer, and a gas relay. The oil tank is made of welded steel plates and is used to hold insulating oil. The main body of an oil-immersed transformer (windings and iron core) is installed in the oil tank and immersed in insulating oil. The insulating oil used in transformers has the advantages of good insulation properties, good thermal conductivity, and low price. It can solve the heat dissipation problems of large-capacity transformers and high-voltage insulation problems. However, because it is a petroleum-based liquid, it has the potential to burn.

[0003] When an arc fault occurs in an oil-immersed transformer, a large amount of gas is generated in a very short period of time, causing a sharp increase in pressure within the tank. If the tank's pressure relief devices (such as pressure relief valves and explosion-proof membranes) are not activated in time, the tank structure will be subjected to the tremendous expansion force and may break at a weak point, causing insulating oil leakage. Moreover, due to the high temperature in this area and the continued arc, it is very likely to cause an explosion.

[0004] At present, in the relevant technology, the above problems are generally solved in two ways. The first is to increase the rigidity of the oil tank structure, such as arranging reinforcing ribs, increasing the thickness of the tank wall, etc. However, excessive structural rigidity will greatly increase the construction cost of the structure. On the other hand, due to the high rigidity, the deformation of the tank body is small, so the energy that the tank body can absorb by deformation will be reduced, so that the tank body only absorbs part of the energy and deforms, but the rest of the energy is confined in the tank body. When the internal pressure of the tank body exceeds the critical value, the tank body is difficult to absorb energy by continuing to deform, and it will directly break. The second is to set up a multi-layer flexible oil tank structure, such as an inner layer of steel plate isolation layer, a middle layer of porous structure, and an outer layer of steel plate support. However, a sufficiently large outer layer buffer space needs to be reserved, which will greatly increase the volume of the oil tank, and the multi-layer steel plate structure will greatly increase the construction cost. In addition, due to the limited space of the oil tank, the arc energy that the buffer structure can absorb is also limited. In the case of a large short-circuit arc fault, the oil tank will still be damaged and explode. Utility Model Content

[0005] In order to solve the above technical problems, an embodiment of the present application provides an oil tank for an oil-immersed transformer and an oil-immersed transformer, and the oil tank can solve the above technical problems.

[0006] In a first aspect, the present application provides a fuel tank for an oil-immersed transformer. The fuel tank includes a main body and a secondary body. The main body defines a first accommodation space, and the first accommodation space is configured to accommodate and carry the transformer body. The secondary body defines a second accommodation space. The secondary body has a folded form and an unfolded form. The volume of the second accommodation space of the secondary body in the folded form is smaller than the volume of the second accommodation space of the secondary body in the unfolded form. The first accommodation space of the main body and the second accommodation space of the secondary body communicate with each other to accommodate insulating oil together.

[0007] Optionally, the second accommodation space has a first volume when the secondary body is in the folded form, and the second accommodation space has a second volume when the secondary body is in the unfolded form. The second volume is greater than the first volume. The secondary body includes a first part. When the pressure in the first accommodation space of the main body that accommodates the transformer body and insulating oil and the second accommodation space of the secondary body in the folded form exceeds a preset range, the first part changes from a folded shape to an unfolded shape, so that the secondary body changes from the folded form to the unfolded form, and the second accommodation space with the second volume and the first accommodation space accommodate insulating oil together.

[0008] Optionally, the fuel tank further includes a connecting member. The connecting member is connected between the main body and the secondary body to hold the secondary body in the folded form. When the secondary body changes from the folded form to the unfolded form, the connecting member disconnects.

[0009] Optionally, the secondary body further includes a second part. The second part is connected to the first part to define the second accommodation space together with the first part. The volume of the sub-accommodation space defined by the second part is fixed. The first part is connected between the second part and the main body. The connecting member is located outside the second part. One end of the connecting member is connected to the outer surface of the main body, and the other end is connected to the outer surface of the second part.

[0010] Optionally, the fuel tank further includes a first roller. The first roller is installed at the bottom of the secondary body.

[0011] Optionally, the fuel tank further includes a guide rail extending in a first direction. The main body and the secondary body are distributed along the first direction. The first roller is guided by the guide rail to roll.

[0012] Optionally, the fuel tank further includes a second roller. The second roller is installed at the bottom of the main body. The second roller is guided by the guide rail to roll.

[0013] Optionally, the main box body has a first opening, and the auxiliary box body has a second opening. The openings of the main box body and the auxiliary box body are arranged opposite to each other along the first direction.

[0014] Optionally, the first opening is a notch in the overall cross-section of the main box body, and the second opening is a notch in the overall cross-section of the auxiliary box body.

[0015] In a second aspect, the present application also provides an oil-immersed transformer, including a transformer body and the above-mentioned fuel tank.

[0016] Through the fuel tank provided by the present application, the internal space of the fuel tank includes the first accommodation space of the main box body and the second accommodation space of the auxiliary box body. Since the volume of the second accommodation space can become larger or smaller as the auxiliary box body switches between the unfolded form and the folded form, the volume of the internal space of the fuel tank can be changed, thereby being able to adapt to the pressure change inside the fuel tank and reducing the probability of the fuel tank being burst. Then, when an arc fault occurs in the transformer body, causing the pressure in the accommodation cavity to rise rapidly, the internal volume of the fuel tank can be expanded by unfolding the auxiliary box body to achieve the effect of reducing the internal pressure of the fuel tank and avoiding damage to the fuel tank. Description of the Drawings

[0017] Figure 1 is a schematic cross-sectional view of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application, where the auxiliary box body is in a folded form;

[0018] Figure 2 is a three-dimensional schematic view of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application, where the auxiliary box body is in a folded form;

[0019] Figure 3 is a three-dimensional schematic view of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application, where the auxiliary box body is in an unfolded form;

[0020] Figure 4 is a three-dimensional view of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application, where the auxiliary box body is in an unfolded form;

[0021] Figure 5 is a three-dimensional view of the main box body of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application;

[0022] Figure 6 is a three-dimensional view of the second part of the auxiliary box body of a fuel tank for an oil-immersed transformer provided by an embodiment of the present application;

[0023] Figure 7 is a three-dimensional view of a partial structure of an oil-immersed transformer provided by an embodiment of the present application, where the auxiliary box body is in a folded form;

[0024] Figure 8 It is a partial enlarged view of an oil-immersed transformer provided by an embodiment of the present application.

[0025] Reference numerals:

[0026] 10 - main box body, 11 - first opening,

[0027] 20 - secondary box body, 21 - first part, 22 - second part,

[0028] 40 - second connecting member, 51 - first roller, 52 - second roller, 60 - guide rail. Detailed implementation manners

[0029] To make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0030] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0031] For an oil-immersed transformer, the fuel tank is filled with insulating oil, and the transformer body is immersed in the insulating oil. Then, when an arc fault occurs in the transformer body, it will cause the internal pressure of the fuel tank to rise rapidly, that is, the air pressure and oil pressure in the fuel tank will rise rapidly. If the internal volume of the fuel tank is fixed, the fuel tank is likely to be burst, resulting in the outflow of insulating oil, which is likely to cause major safety accidents and environmental pollution. Therefore, the present application provides a fuel tank for an oil-immersed transformer, and the internal volume of the fuel tank is variable, which can reduce the probability of the fuel tank being burst.

[0032] Specifically, referring to Figures 1 to 3 , the fuel tank provided by the present application includes a main box body 10 and a secondary box body 20. The secondary box body 20 defines a first accommodation space, wherein the first accommodation space is configured to accommodate and carry the transformer body; the secondary box body 20 defines a second accommodation space, wherein the secondary box body 20 has a folded form and an unfolded form, and the volume of the second accommodation space of the secondary box body in the folded form is smaller than the volume of the second accommodation space of the secondary box body in the unfolded form; wherein, the first accommodation space of the main box body and the second accommodation space of the secondary box body are communicated to accommodate insulating oil together.

[0033] Regarding the auxiliary box body 20, it can be understood that the auxiliary box body 20 can be folded or unfolded, so that the volume of the second accommodation space can be changed. Therefore, when the auxiliary box body 20 is in the folded state, the volume of the second accommodation space is smaller, and when the auxiliary box body 20 is in the unfolded state, the volume of the second accommodation space is larger.

[0034] Regarding the main box body 10, it can be understood that the volume of the main box body 10 is fixed, that is, the volume of the first accommodation space is fixed, so as to be able to accommodate and carry the transformer body.

[0035] Based on the above technical solution, the internal space of the fuel tank includes the first accommodation space of the main box body 10 and the second accommodation space of the auxiliary box body 20. Since the volume of the second accommodation space can become larger or smaller as the auxiliary box body 20 switches between the unfolded state and the folded state, the volume of the internal space of the fuel tank can be changed, so as to adapt to the pressure change inside the fuel tank and reduce the probability of the fuel tank being burst.

[0036] Among them, the second accommodation space has a first volume when the auxiliary box body 20 is in the folded state, and the second accommodation space has a second volume when the auxiliary box body 20 is in the unfolded state, and the second volume is greater than the first volume; the auxiliary box body 20 includes a first part 21. When the pressure in the first accommodation space of the main box body 10 that accommodates the transformer body and the insulating oil and the second accommodation space of the folded auxiliary box body 20 exceeds the preset range, the first part 21 changes from the folded shape to the unfolded shape, so that the auxiliary box body 20 changes from the folded state to the unfolded state, and the second accommodation space with the second volume and the first accommodation space accommodate the insulating oil together. Among them, the first accommodation space and the second accommodation space are communicated, so the pressures of the first accommodation space and the second accommodation space are the same. When the pressure in the first accommodation space and the second accommodation space with the first volume exceeds the preset range, it means that the pressure in the internal space of the fuel tank exceeds the preset range. Since the pressure increases, the first part 21 can change from the folded shape to the unfolded shape, so that the auxiliary box body 20 changes from the folded state to the unfolded state. In this way, the second accommodation space increases from the first volume to the second volume, and then the second accommodation space with the second volume and the first accommodation space accommodate the insulating oil together, which can reduce the pressure and avoid the situation that the fuel tank is burst due to excessive pressure.

[0037] It can be understood that if the pressure difference between the internal pressure of the fuel tank and the external air pressure is too large, it is easy to cause the main box body 10 or the auxiliary box body 20 to burst. Therefore, the preset range can be the range suitable for the normal operation of the transformer body, and moreover, the maximum value of the preset range must be less than the maximum value of the pressure difference that the main box body 10 can withstand and less than the maximum value of the pressure difference that the auxiliary box body 20 can withstand. The user can set the preset range according to the actual situation, and this application does not make a limit.

[0038] For example, when an arc fault occurs in the transformer body, causing the internal pressure of the fuel tank to rise rapidly, the first part 21 can change from the folded shape to the unfolded shape under the action of the internal pressure of the fuel tank, so that the volume of the second accommodation space increases, thereby increasing the internal volume of the fuel tank. Then, the internal pressure of the fuel tank that has risen sharply due to the arc fault will be relieved, making it easy to keep the internal pressure of the fuel tank within a preset range and reducing the probability of the fuel tank being burst. On the contrary, if the internal pressure of the fuel tank decreases for some reason, the auxiliary box body 20 can also change towards the folded state to reduce the second accommodation space, thereby reducing the internal volume of the fuel tank and enabling the internal pressure of the fuel tank to still be kept within the preset range.

[0039] In a possible embodiment, referring to Figure 1 and Figure 7 , the fuel tank further includes a connecting member 40, and the connecting member 40 is connected between the main box body 10 and the auxiliary box body 20 to keep the auxiliary box body 20 in the folded state. When the auxiliary box body 20 changes from the folded state to the unfolded state, the connecting member 40 is disconnected to no longer keep the auxiliary box body 20 in the folded state. It should be understood that when the pressure in the first accommodation space and the second accommodation space of the folded auxiliary box body 20 increases and exceeds the preset range, the auxiliary box body 20 needs to change from the folded state to the unfolded state to expand the volume of the second accommodation space, so as to achieve the effect of relieving the internal space pressure of the fuel tank. Therefore, the pressure exceeding the preset range will act on the connecting member 40 to disconnect the connecting member 40, so that the auxiliary box body 20 can change from the folded state to the unfolded state. Therefore, when it is not necessary to make the second accommodation space in the second volume, the connecting member 40 can be used to keep the auxiliary box body 20 in the folded state. When it is necessary to expand the volume of the second accommodation space to the second volume, the connecting member 40 will be disconnected under the action of the pressure.

[0040] In one example, the connecting member 40 includes a male buckle and a female buckle, and the male buckle and the female buckle can be detachably snapped together. The male buckle is connected to the main box body 10, and the female buckle is connected to the auxiliary box body 20. When the pressure in the first accommodation space and the second accommodation space of the folded auxiliary box body 20 exceeds the preset range, the male buckle and the female buckle are separated. Through this technical solution, the male buckle and the female buckle can be reused, or when the male buckle or the female buckle is damaged, only the male buckle or the female buckle needs to be replaced, without replacing the entire connecting member 40. Among them, the separation of the male buckle and the female buckle can be automatically separated under the action of the pressure, or the user can manually separate the male buckle and the female buckle when it is found that the pressure is too high.

[0041] In another example, the connecting member 40 can be an integrally formed part, and the connecting member 40 breaks when the pressure in the first accommodating space and the second accommodating space of the auxiliary box body 20 in the folded state exceeds a preset range. In this way, the connecting member 40 is disposable and easily breakable, so that it can automatically break under the action of a pressure exceeding the preset range. Among them, the connecting member 40 can be a flexible member or a rigid member, which is not limited in this application. For example, the connecting member 40 can be a nylon rope or a steel wire rope.

[0042] In a possible embodiment, referring to Figure 1 , Figure 7 and Figure 8 , the auxiliary box body 20 further includes a second part 22, and the second part 22 is connected to the first part 21 to jointly define the second accommodating space with the first part 21. The volume of the sub-accommodating space defined by the second part 22 is fixed; the first part 21 is connected between the second part 22 and the main box body 10, and the connecting member 40 is located outside the second part 22. One end of the connecting member 40 is connected to the outer surface of the main box body 10, and the other end is connected to the outer surface of the second part 22. In this way, not only can the state of the connecting member 40 be conveniently observed, but also the connecting member 40 can be prevented from occupying the internal space of the fuel tank, avoiding interference with the installation of the transformer main body, and facilitating the reduction of the overall volume of the fuel tank. Among them, the sub-accommodating space defined by the second part 22 is a part of the second accommodating space.

[0043] In an example, the number of the connecting members 40 can be multiple, and the multiple connecting members 40 are distributed at intervals around the first part 21. In this way, the connection stress between the main box body 10 and the auxiliary box body 20 can be evenly dispersed around the first part 21, which is beneficial to making the connection between the main box body 10 and the auxiliary box body 20 firm. Specifically, the connecting members 40 can be evenly distributed at intervals around the first part 21.

[0044] In a possible implementation manner, referring to Figure 2 and Figure 3 , the fuel tank further includes a first roller 51, and the first roller 51 is installed at the bottom of the auxiliary box body 20. In this way, by providing the first roller 51, when the pressure in the first accommodating space of the main box body 10 accommodating the transformer main body and the insulating oil and the second accommodating space of the auxiliary box body 20 in the folded state exceeds the preset range, the auxiliary box body 20 can quickly move away from the main box body 10 by relying on the first roller 51, so that the first part 21 of the auxiliary box body 20 quickly changes from the folded shape to the unfolded shape, so that the auxiliary box body 20 quickly changes from the folded state to the unfolded state, and then quickly obtains the second accommodating space with the second volume, achieving the effect of quickly reducing the pressure.

[0045] In a possible embodiment, referring to Figure 7 and Figure 8, the fuel tank further includes a guide rail 60 extending in the first direction. The main box body 10 and the auxiliary box body 20 are distributed in the first direction, and the first roller 51 is guided by the guide rail 60 to roll. In this way, through the cooperation of the guide rail 60 and the first roller 51, the moving direction of the auxiliary box body 20 can be restricted to the first direction, so that the first opening 11 and the second opening remain opposite in the first direction, avoiding distortion of the first part 21.

[0046] Further, referring to Figure 2 , Figure 3 and Figure 8 , the fuel tank further includes a second roller 52. The second roller 52 is installed at the bottom of the main box body 10, and the second roller 52 is guided by the guide rail 60 to roll. In this way, both the main box body 10 and the auxiliary box body 20 are located on the guide rail 60, facilitating the installation of the fuel tank. Specifically, the second roller 51 can be installed at the bottom of the second part 22.

[0047] In addition, by providing the first roller 51, a first gap can be formed between the auxiliary box body 20 and the ground or the installation platform. By providing the second roller 52, a second gap can be formed between the main box body 10 and the ground or the installation platform. Through the first gap and the second gap, contact between the first part 21 of the folded auxiliary box body 20 and the ground or the installation platform can be avoided. Here, the installation platform refers to the platform for installing the transformer.

[0048] Further, the number of the guide rails 60 can be two. At least two first rollers 51 and at least two second rollers 52 are provided on each guide rail 60. That is to say, the number of the first rollers 51 is at least four, and the number of the second rollers 52 is at least four. In this way, at least four first rollers 51 are correspondingly arranged on the two guide rails 60, which can stably support the auxiliary box body 20. Similarly, at least four second rollers 52 are correspondingly arranged on the two guide rails 60, which can stably support the main box body 10.

[0049] In a possible embodiment, referring to Figure 4 and Figure 5 , the main box body 10 has a first opening 11, the auxiliary box body 20 has a second opening, and the openings of the main box body 10 and the auxiliary box body 20 are arranged opposite to each other in the first direction. In this way, it is convenient to connect the first opening 11 of the main box body 10 and the second opening of the auxiliary box body 20 together. In an example, the first part 21 of the auxiliary box body 20 can be a cylindrical member with openings at both ends, and the second part 22 can be a cylindrical member with an opening at only one end. One side of the first part 21 is communicated with the first opening 11 of the main box body 10, and the other side is communicated with the opening of the second part 22, thus realizing the connection between the main box body 10 and the auxiliary box body 20. Among them, the second opening is not shown in the figure.

[0050] In one implementation manner, referring to Figure 5and Figure 6 The first opening 11 may be a notch in the overall cross-section of the main housing 10, and the second opening may be a notch in the overall cross-section of the main housing 10. It can be understood that the first opening 11 is not located on a certain surface of the main housing 10, but rather a certain surface of the main housing 10 is missing to form the first opening 11. The second opening is not located on a certain surface of the auxiliary housing 20, but rather a certain surface of the auxiliary housing 20 is missing to form the second opening. For example, the main housing 10 may be a cuboid, and one end surface of the main housing 10 is missing to form the first opening 11. The first part 21 may be a square tube, and one end surface of the square tube is missing to form the second opening. Connecting members 40 are connected to the four side surfaces of the main housing 10 surrounding the first opening 11, and connecting members 40 are connected to the four side surfaces of the auxiliary housing 20 surrounding the second opening.

[0051] In one example, the first part 21 of the auxiliary housing 20 may be made of rubber material, or the first part 21 includes a connecting portion made of flexible rubber material. The rubber material not only facilitates folding and unfolding, but also can be used to contain insulating oil to avoid leakage. Alternatively, the first part 21 may also be a flexible plastic part, or the first part 21 includes a connecting portion made of flexible plastic material. Alternatively, the first part 21 may be a metal bellows.

[0052] In addition, by providing the second part 22 with a fixed volume, it is convenient to manage the folding shape of the first part 21, and it is beneficial to enhance the overall structural strength of the fuel tank and is beneficial to bearing the weight of the insulating oil. It should be understood that after the connecting member 40 is disconnected due to an arc fault occurring in the transformer body, the unfolded first part 21 has corresponding structural strength, can bear the weight of the insulating oil, and can bear the tensile force between the main housing 10 and the auxiliary housing 20, and generally will not be damaged due to this tensile force and the gravity of the insulating oil. Additionally, when no arc fault occurs in the transformer body, the auxiliary housing 20 may be in a folded state. For example, it is maintained in a folded state under the action of the connecting member 40. Specifically, the first part 21 can be folded towards the inside of the second accommodation space to prevent the first part 21 from protruding outside the main housing 10 and the second part 22.

[0053] In a second aspect, based on the above fuel tank, the present application further provides an oil-immersed transformer, including a transformer body and the above fuel tank. In this way, when an arc fault occurs in the transformer body, causing the air pressure and oil pressure inside the fuel tank to rapidly increase, the internal volume of the fuel tank can be expanded by unfolding the auxiliary housing 20, so as to achieve the effect of reducing the internal pressure of the fuel tank and avoiding the fuel tank from being damaged and leaking oil.

[0054] In addition, the oil-immersed transformer may further include a tap changer, which is connected to the transformer body for adjusting the voltage of the transformer. Of course, reinforcing ribs may also be provided on the main tank 10 and the auxiliary tank 20 to enhance the overall structural strength of the oil tank.

[0055] It should be noted that, according to the needs of implementation, each component / step described in the embodiments of the present invention can be split into more components / steps, or two or more components / steps or parts of the operations of the components / steps can be combined into new components / steps to achieve the purpose of the embodiments of the present invention.

[0056] The above embodiments are only used to illustrate the embodiments of the present invention, rather than to limit the embodiments of the present invention. Those of ordinary skill in the relevant technical fields can also make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the embodiments of the present invention. The patent protection scope of the embodiments of the present invention shall be defined by the claims.

Claims

1. An oil tank for an oil-immersed transformer, characterized in that, The fuel tank includes: A main box body (10) that defines a first accommodation space, wherein the first accommodation space is configured to accommodate and carry the transformer body; A secondary box body (20) that defines a second accommodation space, wherein the secondary box body (20) has a folded form and an unfolded form, and the volume of the second accommodation space of the secondary box body (20) in the folded form is smaller than the volume of the second accommodation space of the secondary box body (20) in the unfolded form; Wherein, the first accommodation space of the main box body (10) and the second accommodation space of the secondary box body (20) are communicated to accommodate insulating oil together.

2. The fuel tank for an oil-immersed transformer according to claim 1, wherein The second accommodation space has a first volume when the secondary box body (20) is in the folded form, and the second accommodation space has a second volume when the secondary box body (20) is in the unfolded form, and the second volume is greater than the first volume; The secondary box body (20) includes a first part (21), and when the pressure in the first accommodation space of the main box body (10) that accommodates the transformer body and insulating oil and the second accommodation space of the secondary box body (20) in the folded form exceeds a preset range, the first part (21) changes from a folded shape to an unfolded shape, so that the secondary box body (20) changes from the folded form to the unfolded form, and the second accommodation space with the second volume and the first accommodation space accommodate insulating oil together.

3. The fuel tank for an oil-immersed transformer according to claim 2, characterized in that, The fuel tank further includes a connecting member (40), and the connecting member (40) is connected between the main box body (10) and the secondary box body (20) to hold the secondary box body (20) in the folded form, wherein, When the secondary box body (20) changes from the folded form to the unfolded form, the connecting member (40) disconnects.

4. The fuel tank for an oil-immersed transformer according to claim 3, characterized in that, The secondary box body (20) further includes a second part (22), and the second part (22) is connected to the first part (21) to define the second accommodation space together with the first part (21), and the volume of the sub-accommodation space defined by the second part (22) is fixed; The first part (21) is connected between the second part (22) and the main box body (10), the connecting member (40) is located outside the second part (22), one end of the connecting member (40) is connected to the outer surface of the main box body (10), and the other end is connected to the outer surface of the second part (22).

5. The fuel tank for an oil-immersed transformer according to claim 1, characterized in that, The fuel tank further includes a first roller (51), and the first roller (51) is installed at the bottom of the secondary box body (20).

6. The fuel tank for an oil-immersed transformer according to claim 5, characterized in that, The fuel tank further includes a guide rail (60) extending in a first direction, the main box body (10) and the secondary box body (20) are distributed along the first direction, and the first roller (51) is guided to roll by the guide rail (60).

7. The fuel tank for an oil-immersed transformer according to claim 6, characterized in that, The fuel tank further includes a second roller (52), and the second roller (52) is installed at the bottom of the main box body (10), and the second roller (52) is guided to roll by the guide rail (60).

8. The fuel tank for an oil-immersed transformer according to claim 6, characterized in that, The main housing (10) has a first opening (11), the auxiliary housing (20) has a second opening, and the openings of the main housing (10) and the auxiliary housing (20) are arranged opposite to each other along the first direction.

9. The oil tank for an oil-immersed transformer according to claim 8, characterized in that, The first opening (11) is a notch in the overall cross-section of the main housing (10), and the second opening is a notch in the overall cross-section of the auxiliary housing (20).

10. An oil-immersed transformer, characterized in that, It includes a transformer body and an oil tank according to any one of claims 1-9 above.

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