A reliably grounded oil-immersed transformer

Abstract

This invention discloses a reliably grounded oil-immersed transformer, relating to the field of transformer technology. The reliably grounded oil-immersed transformer includes: a transformer body with a grounding connection terminal; and a conical cavity, threadedly mounted to the outside of the grounding connection terminal. An internal stress dispersion component is disposed within the internal cavity of the conical cavity, forming a multi-stage stress transmission path with the inner wall of the conical cavity. The conical cavity converts axial vibration loads into radial clamping forces, and the multi-stage transmission path constructed by the internal stress dispersion component avoids stress concentration at the connection points and improves overall rigidity, effectively preventing fatigue cracks and adapting to the long-term hot and cold cycle conditions of the transformer. A gradient corrugated buffer structure is provided on the outside of the split-type locking sleeve, forming an elastic buffer zone with a rigid-flexible transition through the axial change in groove depth.

Description

Technical Field

[0001] This invention relates to the field of transformer technology, specifically to an oil-immersed transformer with reliable grounding. Background Technology

[0002] Oil-immersed transformers are electrical devices that use transformer oil for insulation and cooling. To ensure their safe operation, reliable grounding is essential. This involves permanently and securely connecting the metal casing and internal iron core to the earth through a conductor. This allows dangerous current to be conducted to the earth in the event of equipment leakage, preventing electric shock to personnel and eliminating potential internal discharge hazards. It is a fundamental safety measure to ensure stable operation.

[0003] However, current oil-immersed transformers still have the following problems regarding the reliability of grounding connections under complex operating conditions: 1. Grounding plates are usually rigidly connected to the transformer body, lacking an effective stress buffer and dispersion mechanism. This causes high-frequency electromagnetic vibrations, periodic thermal expansion and contraction, and installation pre-tightening forces generated during transformer operation to directly converge at the connection interface. This rigid transmission method is very likely to form high-amplitude stress concentrations at the weld or bolt root. Under long-term alternating loads, fatigue microcracks will inevitably occur at the connection, eventually leading to safety hazards such as grounding circuit breakage or a sharp increase in contact resistance.

[0004] 2. During the long-term operation of transformers, traditional bolted connections are difficult to resist the fretting wear induced by long-term high-frequency vibration, and are prone to gradual loosening. Once loosened, it not only hinders the discharge of fault current, but also causes relative displacement of components due to the loss of axial restraint, resulting in electrical connection failure or even circuit breakage. The maintenance cost is high, the operation is difficult, and it is difficult to eliminate the hidden danger of repeated loosening caused by vibration. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a reliably grounded oil-immersed transformer, solving the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a reliably grounded oil-immersed transformer, comprising: a transformer body, wherein a grounding connection terminal is provided on the transformer body; a conical cavity, wherein the conical cavity is threadedly installed on the outside of the grounding connection terminal, and a stress dispersion component is provided in the internal cavity of the conical cavity, wherein the stress dispersion component and the inner wall of the conical cavity form a multi-stage stress transmission path; a grounding post, wherein the grounding post is electrically connected to the grounding connection terminal, and a split locking sleeve is sleeved on the outside of the grounding post, wherein the split locking sleeve is composed of two half-sleeves joined together, and a continuous annular groove is formed on the outside of the split locking sleeve to form a corrugated buffer structure; and a plug rod, wherein the plug rod is distributed along a spiral trajectory on the outside of the split locking sleeve, the plug rod penetrates the split locking sleeve and is connected to the grounding post, thereby dispersing axial and radial loads to the corrugated buffer structure.

[0007] Furthermore, the stress dispersion component includes dispersion rings uniformly distributed along the axial direction of the conical cavity, forming a mesh gradient support structure.

[0008] Furthermore, the stress dispersion component includes an annular plate uniformly distributed along the axial direction of the conical cavity, and the annular plate is provided with polygonal through holes uniformly distributed in the circumferential direction to form a porous gradient support structure.

[0009] Furthermore, multiple sets of protrusions are evenly distributed along the axial direction on the outer side of the grounding post, and a semi-spiral groove is opened on the inner wall of the half sleeve to cooperate with the corresponding protrusion. The semi-spiral grooves on the inner walls of the two half sleeves rotate in opposite directions, and the protrusions are embedded in the semi-spiral grooves to form a spiral locking fit.

[0010] Furthermore, the groove depth of the annular groove varies in a gradient along the axial direction of the split locking sleeve, and the groove depth on the side closer to the grounding connection end is less than the groove depth on the side farther from the grounding connection end.

[0011] Furthermore, the insertion rod is made of multiple steel wires twisted together, and both the split locking sleeve and the grounding post are provided with spiral insertion holes that cooperate with the insertion rod. A rectangular locking block is fixedly connected to the bottom end of the insertion rod, and a slot that cooperates with the rectangular locking block is provided inside the grounding post.

[0012] Furthermore, a mounting base is rotatably connected to the top of the insertion rod, and adjacent mounting bases are connected by an arc-shaped connecting rod.

[0013] Furthermore, the length of the insertion rod gradually increases along the grounding post from the direction closest to the grounding connection end to the direction furthest from the grounding connection end.

[0014] Furthermore, both ends of the conical cavity are provided with fixing rings sleeved on the outside of the grounding connection end. Two pins are inserted radially on the fixing rings. The pins pass through the fixing rings and are inserted into the grounding connection end. The two pins on the same fixing ring are perpendicular to each other and are inserted into each other.

[0015] Furthermore, a cross-shaped groove is provided at the end of the grounding connection terminal away from the transformer body, and a cross-shaped locking block that mates with the cross-shaped groove is provided at the end of the grounding post near the grounding connection terminal. The cross-shaped locking block is inserted into the corresponding pin.

[0016] The present invention has the following beneficial effects: (1) The reliable grounded oil-immersed transformer converts the axial vibration load into radial clamping force through the conical cavity, and constructs a multi-level transmission path with the internal stress dispersion component to avoid stress concentration at the connection and improve the overall stiffness, effectively prevent fatigue cracks, and adapt to the long-term hot and cold cycle conditions of the transformer.

[0017] (2) The reliable grounded oil-immersed transformer has a gradient corrugated buffer structure on the outside of the split locking sleeve. Through the axial change of the groove depth from shallow to deep, an elastic buffer zone with rigid-flexible transition is formed on the outside of the sleeve. When the external stress is transmitted to the grounding post and then to the split locking sleeve, the gradient corrugated structure takes advantage of the characteristics of high rigidity support at the near end and high flexibility energy absorption at the far end to undergo micro-elastic deformation first, absorb and dissipate most of the vibration energy, effectively avoid stress accumulation at the junction of the grounding post and the grounding connection end, and transform the concentrated load that may lead to fracture into uniformly distributed strain, thereby improving the fatigue resistance of the grounding system.

[0018] (3) The reliable grounding oil-immersed transformer has multiple sets of protrusions evenly arranged along the axial direction on the outside of the grounding post, and a semi-spiral groove that matches the corresponding protrusion is opened on the inner wall of the split locking sleeve. The semi-spiral grooves on the inner walls of the two half sleeves rotate in opposite directions. After installation and mating, the protrusions are embedded in the semi-spiral grooves to form a bidirectional spiral locking fit. This not only evenly converts the load on the grounding post into the axial and radial stress of the sleeve, but also utilizes the self-locking effect of the reverse spiral to effectively resist the circumferential rotation tendency of the grounding post and prevent loosening under the premise of fixing the sleeve outside.

[0019] (4) This reliably grounded oil-immersed transformer effectively diverts axial tension and radial shear force to the high-rigidity area of ​​the sleeve by arranging multiple insert rods along the spiral trajectory on the outside of the split locking sleeve, avoiding local stress concentration. At the same time, the length of the insert rod gradually increases from the near end to the far end, guiding the stress to diffuse evenly from the inside to the outside. In addition, the use of multi-stranded steel wire in conjunction with the spiral insertion hole, and the use of geometric self-locking characteristics to strictly limit radial displacement, prevents the insert rod from being pulled out. The precise engagement of the rectangular locking block at the bottom of the insert rod with the internal slot of the grounding post completely blocks the rotational freedom, eliminates the risk of loosening under complex alternating loads, improves the rigidity and stability of the overall connection, has a high degree of modularity, and is convenient for on-site disassembly and maintenance.

[0020] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the main body of the transformer in this invention; Figure 2 This is a partial structural diagram of the conical cavity, split locking sleeve, and grounding post in this invention; Figure 3 This is a schematic diagram of the grounding connection terminal in this invention; Figure 4 This is a partial cross-sectional view of the conical cavity and the fixing ring in this invention; Figure 5This is a schematic diagram of the stress dispersion component in Embodiment 1 of the present invention; Figure 6 This is a partial cross-sectional view of the grounding post, cross-shaped locking block, and grounding connection end in this invention. Figure 7 This is a partial planar structural diagram of the grounding post and the split locking sleeve in this invention; Figure 8 This is a partial cross-sectional view of the split locking sleeve in this invention; Figure 9 This is a partial cross-sectional view of the grounding post in this invention; Figure 10 This is a schematic diagram of the structure of the insertion rod, rectangular locking block, and arc-shaped connecting rod in this invention; Figure 11 This is a schematic diagram of the grounding post and the split locking sleeve in this invention; Figure 12 This is a schematic diagram of the stress dispersion component in Embodiment 2 of the present invention.

[0022] In the diagram, 1. Transformer body; 11. Grounding connection terminal; 111. Cross groove; 2. Conical cavity; 21. Fixing ring; 211. Pin; 22. Stress dispersion assembly; 221. Dispersion ring; 222. Connecting stiffener; 223. Annular plate; 224. Polygonal through hole; 3. Grounding post; 311. Cross locking block; 32. Split-type locking sleeve; 321. Annular groove; 322. Protrusion; 323. Semi-spiral groove; 324. Insert rod; 325. Rectangular locking block; 328. Mounting base; 329. Arc-shaped connecting rod. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0025] The following is based on Figures 1-12 This invention describes a reliably grounded oil-immersed transformer provided by an embodiment of the present invention.

[0026] Example 1, please refer to this example. Figures 1-11 .

[0027] Please refer to Figure 1 and Figure 3 The reliably grounded oil-immersed transformer includes a transformer body 1, on which a grounding connection terminal 11 is provided. The grounding connection terminal 11 serves as the core hub for electrical conduction and mechanical support, used to safely conduct internal fault current or induced charge into the ground. At the same time, it serves as the mounting base for external grounding components, bearing electromagnetic vibration loads and thermal expansion and contraction stress during long-term operation, ensuring that the grounding path always maintains a low-resistance connection and the integrity of the mechanical structure under complex operating conditions.

[0028] Please refer to Figures 2-4 To suppress electromagnetic vibration and stress concentration caused by thermal expansion and contraction during long-term operation of the transformer, a conical cavity 2 is threaded onto the outside of the grounding connection end 11. The tapered structure gradually narrows from near the grounding connection end 11 to the far end, which can convert axial load into radial component force, effectively buffering and dispersing stress at the connection. Both ends of the conical cavity 2 are provided with fixing rings 21 sleeved on the outside of the grounding connection end 11 to implement bidirectional axial limiting. Two pins 211 are inserted radially on the fixing ring 21. The pins 211 pass through the fixing ring 21 and are inserted into the grounding connection end 11. The two pins 211 on the same fixing ring 21 are perpendicular to each other and are inserted into each other. The mechanical interlocking between the pins 211 forms a self-locking mechanism, which can prevent the risk of loosening due to vibration and transfer and disperse part of the stress on the grounding connection end 11 to the conical cavity 2 and the pin 211 structure. While improving the reliability and durability of the connection, it also facilitates on-site disassembly and assembly.

[0029] In use, the inner fixing ring 21, the conical cavity 2, and the outer fixing ring 21 can be sequentially fitted onto the grounding connection end 11. The conical cavity 2 can be screwed onto the preset thread section of the grounding connection end 11 to position it axially. Then, two pins 211 are inserted vertically and alternately into the corresponding holes of the fixing ring 21 and the grounding connection end 11, so that the pins 211 are interlocked and engaged. This completes the axial locking of the fixing ring 21 and the self-locking of the pins 211 in one go, ensuring that the conical cavity 2 and the grounding connection end 11 form a rigid and stable integral connection, effectively resisting external impacts.

[0030] Please refer to Figure 5A stress dispersion component 22 is provided in the internal cavity of the conical cavity 2. The stress dispersion component 22 and the inner wall of the conical cavity 2 form a multi-level stress transmission path. Specifically, the stress dispersion component 22 includes dispersion rings 221 that are uniformly distributed along the axial direction of the conical cavity 2. The dispersion rings 221 are connected by circumferentially uniformly distributed connecting stiffeners 222 to form a mesh gradient support structure. The component is made of a high-elasticity alloy material. When the grounding connection end 11 transmits vibration load, the mesh structure undergoes multi-level micro-elastic deformation, which uniformly diffuses the concentrated stress to the entire inner wall of the conical cavity 2. The vibration energy is dissipated by the hysteresis effect of the metal material, thereby improving the overall stiffness and fatigue resistance of the structure.

[0031] Please refer to Figure 3 , Figure 4 and Figure 6 A grounding post 3 is provided at the small diameter end of the conical cavity 2. The grounding post 3 is conductively connected to the grounding connection end 11 to construct a low-impedance safety discharge channel. The other end of the grounding post 3 can be connected to the earth grounding grid through the grounding down conductor. Specifically, a cross groove 111 is provided at the end of the grounding connection end 11 away from the transformer body 1. A cross locking block 311 that cooperates with the cross groove 111 is provided at the end of the grounding post 3 near the grounding connection end 11. The cross locking block 311 is inserted and cooperates with the corresponding pin 211.

[0032] During installation, the cross-shaped locking block 311 is first inserted into the cross-shaped groove 111 to achieve circumferential positioning and initial locking. Then, the interlocking pin 211 on the fixing ring 21 is inserted one after another, so that the pin 211 passes through the fixing ring 21, the grounding connection end 11 and the cross-shaped locking block 311 at the same time, completing axial limiting, circumferential anti-rotation and mechanical self-locking in one go, ensuring that the grounding post 3 and the grounding connection end 11 form a stable and reliable rigid electrical connection under strong vibration.

[0033] Please refer to Figure 2 A split locking sleeve 32 is fitted on the outside of the grounding post 3. The split locking sleeve 32 is composed of two half sleeves joined together and fastened together by a clamp. In use, the two half sleeves are joined together and attached to the outer periphery of the grounding post 3 to form a complete split locking sleeve 32. Then, the clamp is used to apply a locking force to complete the fastening assembly. The split locking sleeve 32 can be further fixed to an external fixing seat (not shown in the figure) to achieve external anchoring of the overall structure and enhance the stability of the system.

[0034] Please refer to Figure 7 , Figure 9 and Figure 11The split locking sleeve 32 has a continuous annular groove 321 on its outer side, forming a corrugated buffer structure. The groove depth of the annular groove 321 varies in gradient along the axial direction of the split locking sleeve 32, and the groove depth on the side closer to the grounding connection end 11 is smaller than the groove depth on the side farther from the grounding connection end 11. The main body of the split locking sleeve 32 is made of a high-elasticity alloy material. When external stress is transmitted to the grounding post 3 and then to the split locking sleeve 32, the gradient corrugated structure takes advantage of the characteristics of high rigidity support at the near end and high flexibility energy absorption at the far end to undergo micro-elastic deformation first, absorbing and dissipating most of the vibration energy. This effectively avoids stress accumulation at the junction of the grounding post 3 and the grounding connection end 11, and transforms the concentrated load that may lead to fracture into a uniformly distributed strain, thereby improving the fatigue resistance of the grounding system.

[0035] Please refer to Figure 6 , Figure 7 , Figure 9 and Figure 11 To enhance the connection stability between the grounding post 3 and the split locking sleeve 32, ensure that circumferential vibration does not weaken the fastening effect and achieve uniform load transfer, multiple sets of protrusions 322 are evenly distributed along the axial direction on the outer side of the grounding post 3. The inner wall of the half sleeve is provided with a semi-spiral groove 323 that mates with the corresponding protrusion 322. The semi-spiral grooves 323 on the inner walls of the two half sleeves rotate in opposite directions. After installation and alignment, the protrusions 322 are embedded in the semi-spiral grooves 323 to form a bidirectional spiral locking fit. This not only evenly converts the load on the grounding post 3 into axial and radial stresses of the split locking sleeve 32, but also utilizes the self-locking effect of the reverse spiral to effectively resist the circumferential rotation tendency of the grounding post 3 and prevent loosening under the premise of external fixation of the split locking sleeve 32.

[0036] Please refer to Figure 2 To further distribute the stress on the grounding post 3 evenly outward, multiple insert rods 324 are distributed along a spiral trajectory on the outside of the split locking sleeve 32. The insert rods 324 penetrate the split locking sleeve 32 and are connected to the grounding post 3. While strengthening the axial fixation of the split locking sleeve 32 and the grounding post 3, the spiral distribution position of the insert rods 324 is circumferentially offset from the trough position of the corrugated buffer structure, thereby effectively diverting and transferring the axial tensile force and radial shear force to the high-rigidity area of ​​the corrugated structure, avoiding local stress concentration, and achieving overall balanced load dissipation.

[0037] Please refer to Figures 7-10The length of the insertion rod 324 gradually increases along the grounding post 3 from near the grounding connection end 11 to away from the grounding connection end 11. The short rod at the near end effectively avoids the additional bending moment that may be generated, ensuring the pure shear stress state of the root connection to enhance stability. The long rod at the far end increases the shear bearing capacity by increasing the lever arm. On the basis of ensuring the connection stability between the insertion rod 324 and the grounding post 3 and the split locking sleeve 32, a stepped load transfer path is constructed to guide the stress on the grounding post 3 to diffuse from the inside to the outside step by step, further optimizing the stress distribution uniformity of the overall structure.

[0038] Specifically, please refer to Figures 8-10 The insertion rod 324 is made of multiple strands of steel wire and has a spiral shape. Both the split locking sleeve 32 and the grounding post 3 have spiral insertion holes that mate with the insertion rod 324. Utilizing the geometric self-locking characteristics of the spiral pair, the insertion rod 324 is strictly limited in the radial direction and cannot be pulled out directly, thereby effectively resisting the radial impact load on the grounding post 3 and preventing the connection from loosening. A rectangular locking block 325 is fixedly connected to the bottom end of the insertion rod 324. The grounding post 3 has a slot that mates with the rectangular locking block 325. The slot blocks the rotational degree of freedom, and the spiral blocks the axial displacement. The combined effect of the two completely eliminates the risk of the insertion rod 324 loosening or coming out under complex alternating loads. Moreover, the stranded steel wire structure has a certain degree of flexibility and can adapt to minor installation errors, avoiding hard jamming.

[0039] Please refer to Figures 8-10 To ensure that the insertion rod 324 can be smoothly screwed into the spiral insertion hole and accurately positioned, a mounting base 328 is rotatably connected to the top of the insertion rod 324. During installation, the insertion rod 324 is rotated and moves down along the spiral trajectory. Using the guide stroke reserved in the spiral insertion hole, the rectangular locking block 325 at the bottom end is guided to slide into the slot without interference. Adjacent mounting bases 328 are connected by an arc-shaped connecting rod 329. The arc-shaped connecting rod 329 is made of flexible material or adopts a flexible chain structure.

[0040] During assembly, after all the plug rods 324 are screwed in and locked one by one, the adjacent plug rods 324 are connected in series to form a whole by the arc-shaped connecting rod 329. This flexible connection structure can adapt to the small positional deviations between the plug rods 324. When the transformer vibrates during operation, the load distribution of each plug rod 324 is dynamically adjusted by flexible deformation, which effectively equalizes the stress state and avoids the failure of a single plug rod 324 due to overload, thereby significantly improving the stability and fatigue resistance reliability of the overall connection system.

[0041] In practical use, first, insert the inner fixing ring 21, the conical cavity 2, and the outer fixing ring 21 into the grounding connection end 11 in sequence. After tightening the conical cavity 2 to the predetermined position, insert the inner pin 211 to complete the end locking. Then, align the cross-shaped locking block 311 at the end of the grounding post 3 with the cross-shaped groove 111 embedded in the grounding connection end 11 to achieve initial positioning. Next, insert the outer pin 211 through the fixing ring 21 and the cross-shaped locking block 311 to complete the front-end self-locking fixation. Then, align the two halves of the split locking sleeve 32 together and tighten them on the outside of the grounding post 3, using clamps to secure them. Anchored to the external fixing seat, the semi-spiral groove 323 on the inner wall of the split locking sleeve 32 tightly engages with the protrusion 322 on the grounding post 3. Finally, the plug rods 324 are screwed in one by one, so that the rectangular locking block 325 at the bottom end is embedded in the internal slot of the grounding post 3 to block radial displacement. Then, the mounting seat 328 at the top of the adjacent plug rods 324 is directly connected in series through the arc-shaped connecting rod 329. The flexible characteristics of the arc-shaped connecting rod 329 are used to directly equalize the force on each plug rod 324, and finally a complete grounding system with high rigidity connection, multi-level stress dispersion and excellent vibration resistance is constructed.

[0042] Example 2, please refer to this example. Figure 12 .

[0043] The difference between this embodiment and Embodiment 1 is that the stress dispersion component 22 here includes annular plates 223 evenly distributed along the axial direction of the conical cavity 2. The annular plates 223 are connected by circumferentially evenly distributed connecting ribs 222. The annular plates 223 are provided with circumferentially evenly distributed polygonal through holes 224 to form a porous gradient support structure. This structure provides more elastic deformation space while ensuring support stiffness, further improving energy absorption efficiency.

[0044] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0045] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A reliably grounded oil-immersed transformer, characterized in that, include: The transformer body (1) is provided with a grounding connection terminal (11). A conical cavity (2) is threadedly installed on the outside of the grounding connection end (11). A stress dispersion component (22) is provided in the internal cavity of the conical cavity (2). The stress dispersion component (22) and the inner wall of the conical cavity (2) form a multi-level stress transmission path. Grounding post (3), the grounding post (3) is connected to the grounding connection end (11) in a conductive manner, and a split locking sleeve (32) is sleeved on the outside of the grounding post (3). The split locking sleeve (32) is composed of two half sleeves joined together. A continuous annular groove (321) is opened on the outside of the split locking sleeve (32) to form a corrugated buffer structure. Insert rod (324), which is distributed along a spiral trajectory on the outside of the split locking sleeve (32), the insert rod (324) passes through the split locking sleeve (32) and is connected to the grounding post (3), distributing axial and radial loads to the corrugated buffer structure.

2. The oil-immersed transformer with reliable grounding according to claim 1, characterized in that, The stress dispersion component (22) includes dispersion rings (221) uniformly distributed along the axial direction of the conical cavity (2), forming a mesh gradient support structure.

3. The oil-immersed transformer with reliable grounding according to claim 1, characterized in that, The stress dispersion component (22) includes an annular plate (223) uniformly distributed along the axial direction of the conical cavity (2), and the annular plate (223) has polygonal through holes (224) uniformly distributed in the circumferential direction to form a porous gradient support structure.

4. The oil-immersed transformer with reliable grounding according to claim 1, characterized in that, The grounding post (3) has multiple sets of protrusions (322) evenly distributed along the axial direction on the outer side. The inner wall of the half sleeve is provided with a semi-spiral groove (323) that matches the corresponding protrusion (322). The semi-spiral grooves (323) on the inner walls of the two half sleeves rotate in opposite directions. The protrusion (322) is embedded in the semi-spiral groove (323) to form a spiral locking fit.

5. The oil-immersed transformer with reliable grounding according to claim 4, characterized in that, The groove depth of the annular groove (321) varies in gradient along the axial direction of the split locking sleeve (32), and the groove depth on the side closer to the grounding connection end (11) is less than the groove depth on the side farther from the grounding connection end (11).

6. The oil-immersed transformer with reliable grounding according to claim 5, characterized in that, The insertion rod (324) is made of multiple steel wires twisted together. Both the split locking sleeve (32) and the grounding post (3) are provided with spiral insertion holes that cooperate with the insertion rod (324). The bottom end of the insertion rod (324) is fixedly connected to a rectangular card block (325). The grounding post (3) is provided with a card groove that cooperates with the rectangular card block (325).

7. The oil-immersed transformer with reliable grounding according to claim 6, characterized in that, The top end of the insertion rod (324) is rotatably connected to a mounting base (328), and adjacent mounting bases (328) are connected by an arc-shaped connecting rod (329).

8. The oil-immersed transformer with reliable grounding according to claim 7, characterized in that, The length of the insertion rod (324) gradually increases along the grounding post (3) from the direction close to the grounding connection end (11) to the direction far away from the grounding connection end (11).

9. A reliably grounded oil-immersed transformer according to claim 2 or 3, characterized in that, Both ends of the conical cavity (2) are provided with a fixing ring (21) sleeved on the outside of the grounding connection end (11). Two pins (211) are inserted radially on the fixing ring (21). The pins (211) pass through the fixing ring (21) and are inserted into the grounding connection end (11). The two pins (211) on the same fixing ring (21) are perpendicular to each other and are inserted into each other.

10. A reliably grounded oil-immersed transformer according to claim 9, characterized in that, The grounding connection end (11) has a cross groove (111) at the end away from the transformer body (1), and the grounding post (3) has a cross locking block (311) that cooperates with the cross groove (111) at the end near the grounding connection end (11). The cross locking block (311) is inserted into the corresponding pin (211).

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