High-voltage pile head oil-immersed transformer with protection performance

Abstract

The invention relates to the technical field of oil-immersed transformers, and discloses an oil-immersed transformer with a high-voltage pile head having protection performance, which comprises an oil tank, a high-voltage side pile head, a low-voltage side pile head and an oil conservator, and is characterized in that a protection cover is fixedly mounted at the upper end of the high-voltage side pile head, and a telescopic protection sleeve is fixedly mounted in the protection cover; a plurality of bristles are fixedly mounted on the inner wall of the protective sleeve, the protective sleeve covers the outer side of the high-pressure side pile head, and the bristles make contact with the outer surface of the high-pressure side pile head; a rubber pipeline is embedded in the surface of the protective sleeve, and a flexible balance weight ring is fixedly installed on the lower side of the protective sleeve. According to the oil-immersed transformer, the protection cover and the protection sleeve are arranged on the high-voltage side pile head, the protection sleeve covers the outer side of the high-voltage side pile head, the good protection and dustproof effects are achieved, the protection sleeve can retract into the protection cover, the high-voltage side pile head is exposed for heat dissipation, and a good protection and heat dissipation environment is created for the high-voltage pile head of the transformer; and the overheating failure rate is reduced.

Description

Technical Field

[0001] This invention relates to the field of oil-immersed transformer technology, and more particularly to an oil-immersed transformer with protective features at the high-voltage pile head. Background Technology

[0002] Oil-immersed transformers are electrical devices used to exchange voltage and current when transmitting alternating current. To prevent dust contamination of the high-voltage terminals, which could affect the transformer's insulation and heat dissipation, a patent document with publication number CN110828111B discloses an oil-immersed transformer designed to prevent dust accumulation. This transformer includes a transformer, an oil level gauge, high-voltage terminals, and low-voltage terminals. The transformer has a mounting base at its bottom and an end cover on its top. An oil level gauge is mounted on the upper left surface of the end cover, and a rubber sealing ring is provided on the upper surface of the end cover. An exhaust pipe is embedded in the front of the dust cover, and protective cover screws are installed on the outside of the dust cover. A first filter screen is embedded in the rear of the dust cover, and a second filter screen is installed inside the lower part of the air inlet pipe. The main shaft passes through the air inlet pipe, and the protective pipe is installed on the outside of the air inlet pipe. This dust cover design effectively seals and protects the high-voltage and low-voltage terminals, preventing dust from accumulating on the insulators outside the high-voltage and low-voltage terminals, thus increasing the device's dustproof performance.

[0003] Statistics show that overheating of the conductor lead joints, leading to damage or power outages, accounts for more than half of all transformer failures. In particular, overheating of the high-voltage terminals can cause aging and oil leakage of the terminal seals, with oil overflowing into the bushings and adhering to conductive metal dust. When humidity increases due to rain or snow, and overvoltage occurs, bushing flashover or explosion may occur. The above-mentioned solution places the high-voltage terminals inside the dust cover, which affects airflow and reduces the heat dissipation performance of the high-voltage terminals. Therefore, the existing protection design of the high-voltage terminals of oil-immersed transformers has the defect of not being able to create a good heat dissipation environment and needs further improvement. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing oil-immersed transformer high-voltage terminal protection designs, which make it difficult to create a good heat dissipation environment. Therefore, this invention proposes an oil-immersed transformer with protective features for the high-voltage terminals.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an oil-immersed transformer with protective high-voltage terminals, comprising an oil tank, a high-voltage side terminal, a low-voltage side terminal, and an oil conservator, characterized in that: a protective cover is fixedly installed on the upper end of the high-voltage side terminal, a telescopic protective sleeve is fixedly installed inside the protective cover, a plurality of bristles are fixedly installed on the inner wall of the protective sleeve, the protective sleeve covers the outer side of the high-voltage side terminal, and the bristles are in contact with the outer surface of the high-voltage side terminal;

[0006] The surface of the protective sleeve is embedded with rubber tubing, and a flexible counterweight ring is fixedly installed on the lower side of the protective sleeve. The bottom end of the rubber tubing is connected to the inner cavity of the flexible counterweight ring.

[0007] A pump assembly is fixedly installed inside the oil tank, and the pump assembly stores insulating oil. A delivery pipeline is installed inside the oil tank and the high-voltage side terminal. The pump assembly is connected to the upper end of the rubber hose through the delivery pipeline. When the pump assembly pumps the insulating oil into the flexible counterweight ring, the weight of the flexible counterweight ring increases, and the protective sleeve is stretched downward and extended. When the pump assembly sucks the insulating oil back, the protective sleeve retracts and stores it in the protective cover. The extendable and retractable design of the protective sleeve creates a better protection and heat dissipation environment for the high-voltage terminal of the transformer, reducing the overheating failure rate.

[0008] Preferably, the pump suction assembly includes an oil storage sleeve and a telescopic electromagnet. The oil storage sleeve is fixedly installed inside the oil tank. A first piston is slidably installed inside the oil storage sleeve, dividing the inner cavity of the oil storage sleeve into a first chamber and a second chamber. The telescopic electromagnet is fixedly installed on the upper side of the oil tank. The first piston is driven to slide up and down by the telescopic electromagnet. The insulating oil is stored in the first chamber. The delivery pipeline is connected to the first chamber. Driven by the telescopic electromagnet, the insulating oil in the oil storage sleeve is used as a medium to provide power for the telescopic movement of the protective sleeve, which drives the internal bristles to move up and down to clean the dust accumulated on the surface of the high-voltage side terminal head. This allows the transformer to actively clean dust without interrupting power, providing convenience for later maintenance.

[0009] Preferably, the pump suction assembly further includes a pressure relief sleeve, which is fixedly installed on the upper surface of the oil tank. A second piston is slidably installed inside the pressure relief sleeve, which divides the inner cavity of the pressure relief sleeve into a third chamber and a fourth chamber. The third chamber is connected to the inner cavity of the oil tank through a connecting pipe with a pressure relief valve. A pressure relief pipe with a pressure relief valve is fixedly installed on the outer wall of the pressure relief sleeve, and the pressure relief pipe is connected to the third chamber. A drive shaft is fixedly installed between the first piston and the second piston.

[0010] The telescopic electromagnet is fixedly installed at the top of the pressure relief sleeve. The telescopic end of the telescopic electromagnet extends into the pressure relief sleeve and is fixedly connected to the upper end face of the second piston. The drive shaft slides through the top wall of the oil tank, and a sealing ring is provided between the drive shaft and the top wall of the oil tank.

[0011] The insulating oil in the oil storage sleeve is separated from the insulating oil in the oil tank by the oil storage sleeve. When the insulating oil in the oil tank expands due to heat, the insulating oil in the oil tank enters the third chamber through the connecting pipe. The pressure in the third chamber increases, pushing the second piston upward. At the same time, the first piston moves upward, drawing the insulating oil in the flexible counterweight ring back into the first chamber, causing the protective sleeve to contract and store inside the protective cover. When the pressure in the third chamber increases to a certain value, the pressure relief valve automatically opens, and the insulating oil in the third chamber is discharged through the pressure relief pipe. When the transformer overheats due to factors such as faults or overload operation, the protective sleeve automatically changes from an expanded state to a contracted state, which is beneficial for the heat dissipation of the exposed high-voltage side pile head and greatly improves its safety.

[0012] Preferably, an overflow storage tank is fixedly installed on the surface of the oil tank, the bottom end of the pressure relief pipe extends into the overflow storage tank, and a return pipe is fixedly installed on the upper side of the overflow storage tank. The second chamber and the fourth chamber are connected to the overflow storage tank through the return pipe. The insulating oil overflowing from the oil tank and the pumping assembly is recovered through the overflow storage tank and then pumped back to the oil conservator for recycling.

[0013] Preferably, the protective sleeve is a corrugated rubber sleeve, the protective cover is made of epoxy resin material, a first magnetic ring is fixedly installed on the lower side of the protective cover, and a second magnetic ring is embedded inside the flexible counterweight ring. When the protective sleeve is shrunk and stored inside the protective cover, the first magnetic ring and the second magnetic ring are magnetically attracted, so that the protective sleeve is hidden inside the protective cover when not in use, thus extending its service life.

[0014] Preferably, there are three high-voltage side terminals, each equipped with a protective cover and a protective sleeve. Insulating oil is pumped into the three protective sleeves by a pumping assembly, making the three high-voltage side terminals independent of each other and having sufficient safety distance. Compared with placing each high-voltage terminal in the same dust cover, this reduces the risk of flashover discharge between terminals.

[0015] The present invention has the following beneficial effects:

[0016] 1. The oil-immersed transformer proposed in this invention has a protective cover and a protective sleeve installed on the high-voltage side terminal. The protective sleeve is installed on the outside of the high-voltage side terminal, which plays a good role in protection and dust prevention. The protective sleeve can be retracted into the protective cover, so that the high-voltage side terminal is exposed for heat dissipation, creating a better protection and heat dissipation environment for the high-voltage terminal of the transformer and reducing the overheating failure rate.

[0017] 2. The oil-immersed transformer proposed in this invention features a pumping assembly. A telescopic electromagnet, carrying a energized first piston, slides back and forth, using the insulating oil in the oil storage sleeve as a medium to power the telescopic movement of the protective sleeve. During this movement, the internal brush bristles move up and down, cleaning the accumulated dust on the surface of the high-voltage side terminals. Because the low-voltage current of the telescopic electromagnet maintains a sufficient safe distance from the high-voltage current of the transformer, the transformer can actively clean dust without interrupting power, facilitating future maintenance.

[0018] 3. In the oil-immersed transformer proposed in this invention, when the transformer overheats due to factors such as faults or overload operation, the insulating oil in the oil tank enters the third chamber through the connecting pipe because the pumping assembly is also equipped with a pressure relief sleeve. The pressure in the third chamber increases, pushing the second piston to move upward. At the same time, the first piston moves upward, drawing the insulating oil in the flexible counterweight ring back into the first chamber, causing the protective sleeve to shrink and store inside the protective cover. That is, the protective sleeve automatically changes from an unfolded state to a retracted state, which is beneficial for the heat dissipation of the exposed high-voltage side pile head and further improves its safety.

[0019] 4. The oil-immersed transformer proposed in this invention has independent protective sleeves on each of the three high-voltage side terminals, making the protective mechanisms of the three high-voltage side terminals independent of each other and having sufficient safety distance. Compared with placing each high-voltage terminal in the same dust cover, this design reduces the risk of flashover discharge between terminals and is more reasonable and safer. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the oil-immersed transformer proposed in this invention;

[0021] Figure 2 This is a partial cross-sectional three-dimensional structural diagram of the oil-immersed transformer proposed in this invention;

[0022] Figure 3 for Figure 1 Enlarged schematic diagram of the structure at point A in the diagram;

[0023] Figure 4 This is a three-dimensional structural diagram of the high-pressure side pile head proposed in this invention;

[0024] Figure 5 This is a schematic diagram of the front section structure of the high-pressure side pile head proposed in this invention;

[0025] Figure 6 This is a three-dimensional structural diagram of the protective sleeve proposed in this invention;

[0026] Figure 7 This is a schematic cross-sectional view of the pump suction assembly proposed in this invention. Figure 1 ;

[0027] Figure 8 This is a schematic cross-sectional view of the pump suction assembly proposed in this invention. Figure 2 ;

[0028] Figure 9 This is a schematic diagram of the front section of the oil-immersed transformer proposed in this invention.

[0029] In the diagram: 1. Oil tank, 2. High-pressure side pile head, 3. Low-pressure side pile head, 4. Oil conservator, 5. Protective cover, 6. Protective sleeve, 7. Brush bristles, 8. Rubber hose, 9. Flexible counterweight ring, 10. Delivery pipeline, 11. Oil storage sleeve, 12. Telescopic electromagnet, 13. First piston, 14. First chamber, 15. Second chamber, 16. Second piston, 17. Third chamber, 18. Fourth chamber, 19. Pressure relief valve, 20. Pressure relief pipe, 21. Drive shaft, 22. Sealing ring, 23. Overflow storage tank, 24. Return pipe, 25. First magnetic ring, 26. Second magnetic ring, 27. Pressure relief sleeve, 28. Connecting pipe. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0031] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Reference Figures 1-9 An oil-immersed transformer with high-voltage terminal protection includes an oil tank 1, a high-voltage side terminal 2, a low-voltage side terminal 3, and an oil conservator 4. The oil tank 1 contains an iron core, high and low voltage windings, and insulating oil. Radiators are installed on both sides of the oil tank 1. When there is a temperature difference between the upper and lower insulating oil temperatures, oil convection occurs through the radiators, and the oil flows back to the oil tank 1 after being cooled by the radiators, thus reducing the transformer temperature. The oil conservator 4 is an oil protection device. It is a cylindrical container made of steel plate, horizontally installed on the upper side of the oil tank 1, and connected to the oil tank 1 by a bent pipe. When the volume of the transformer oil expands or contracts with the oil temperature, the oil conservator 4 plays the role of storing and replenishing oil, thereby ensuring that the oil tank 1 is full of oil. At the same time, the oil conservator 4 reduces the contact area between the transformer oil and the air, reducing the rate of oil deterioration. This is a conventional setting in existing oil-immersed transformers and will not be described in detail here.

[0033] A protective cover 5 is fixedly installed on the upper end of the high-pressure side pile head 2. A telescopic protective sleeve 6 is fixedly installed inside the protective cover 5. Several bristles 7 are fixedly installed on the inner wall of the protective sleeve 6, such as... Figure 6 As shown, the protective sleeve 6 is placed on the outside of the high-voltage side pile head 2, and the bristles 7 are in contact with the outer surface of the high-voltage side pile head 2.

[0034] Among them, the protective sleeve 6 is a corrugated rubber sleeve, and the protective cover 5 is made of epoxy resin material.

[0035] A rubber tube 8 is embedded in the surface of the protective sleeve 6, and a flexible counterweight ring 9 is fixedly installed on the lower side of the protective sleeve 6. The bottom end of the rubber tube 8 is connected to the inner cavity of the flexible counterweight ring 9. Figure 5 As shown.

[0036] Among them, reference Figure 4 A first magnetic ring 25 is fixedly installed on the lower side of the protective cover 5, and a second magnetic ring 26 is embedded inside the flexible counterweight ring 9.

[0037] A pump suction assembly is fixedly installed inside the oil tank 1. The pump suction assembly stores insulating oil. A delivery pipeline 10 is installed inside the oil tank 1 and the high-voltage side pile head 2. The pump suction assembly is connected to the upper end of the rubber hose 8 through the delivery pipeline 10. When the pump suction assembly pumps the insulating oil into the flexible counterweight ring 9, the weight of the flexible counterweight ring 9 increases and stretches the protective sleeve 6 downward. When the pump suction assembly sucks the insulating oil back, the protective sleeve 6 retracts and stores it inside the protective cover 5. When the protective sleeve 6 retracts and stores it inside the protective cover 5, the first magnetic ring 25 and the second magnetic ring 26 are magnetically attracted.

[0038] For details, please refer to Figure 7 The pump suction assembly includes an oil storage sleeve 11 and a telescopic electromagnet 12. The oil storage sleeve 11 is fixedly installed inside the oil tank 1. A first piston 13 is slidably installed inside the oil storage sleeve 11. The first piston 13 divides the inner cavity of the oil storage sleeve 11 into a first chamber 14 and a second chamber 15. The telescopic electromagnet 12 is fixedly installed on the upper side of the oil tank 1. The first piston 13 is driven to slide up and down by the telescopic electromagnet 12. The insulating oil is stored in the first chamber 14. The delivery pipeline 10 is connected to the first chamber 14.

[0039] In this embodiment, reference Figure 7 The pump suction assembly also includes a pressure relief sleeve 27, which is fixedly installed on the upper surface of the oil tank 1. A second piston 16 is slidably installed inside the pressure relief sleeve 27. The second piston 16 divides the inner cavity of the pressure relief sleeve 27 into a third chamber 17 and a fourth chamber 18. The third chamber 17 is connected to the inner cavity of the oil tank 1 through a connecting pipe 28 with a pressure relief valve 19. A pressure relief pipe 20 with a pressure relief valve 19 is fixedly installed on the outer wall of the pressure relief sleeve 27. The pressure relief pipe 20 is connected to the third chamber 17. A drive shaft 21 is fixedly installed between the first piston 13 and the second piston 16.

[0040] The telescopic electromagnet 12 is fixedly installed at the top of the pressure relief sleeve 27. The telescopic end of the telescopic electromagnet 12 extends into the pressure relief sleeve 27 and is fixedly connected to the upper end face of the second piston 16. The drive shaft 21 slides through the top wall of the oil tank 1, and a sealing ring 22 is provided between the drive shaft 21 and the top wall of the oil tank 1.

[0041] refer to Figure 8 H1 represents the pressure relief valve 19 on the pressure relief pipe 20, and the pressure set by H1 is F1; H2 represents the pressure relief valve 19 on the connecting pipe 28, and the pressure set by H2 is F1; where F1 > F2;

[0042] The insulating oil in the oil storage sleeve 11 and the insulating oil in the oil tank 1 are separated by the oil storage sleeve 11. When the insulating oil in the oil tank 1 is heated and expands, the oil pressure in the oil tank 1 is greater than F2, and H2 opens. The insulating oil in the oil tank 1 enters the third chamber 17 through the connecting pipe 28. The pressure in the third chamber 17 increases, pushing the second piston 16 to move upward. At the same time, the first piston 13 moves upward, drawing the insulating oil in the flexible counterweight ring 9 back into the first chamber 14, causing the protective sleeve 6 to contract and store in the protective cover 5. When the pressure in the third chamber 17 increases to a certain value, that is, when the oil pressure in the third chamber 17 is greater than F1, H1 opens automatically, and the insulating oil in the third chamber 17 is discharged through the pressure relief pipe 20.

[0043] An overflow storage tank 23 is fixedly installed on the surface of the oil tank 1. The bottom end of the pressure relief pipe 20 extends into the overflow storage tank 23. A return pipe 24 is fixedly installed on the upper side of the overflow storage tank 23. The second chamber 15 and the fourth chamber 18 are connected to the overflow storage tank 23 through the return pipe 24. The insulating oil overflowing from the oil tank 1 and the pumping assembly is recovered through the overflow storage tank 23 and then pumped back to the oil conservator 4 for recycling.

[0044] like Figure 1 , Figure 2 As shown, there are three high-voltage side pile heads 2, and each of the three high-voltage side pile heads 2 is equipped with a protective cover 5 and a protective sleeve 6. Insulating oil is pumped into the three protective sleeves 6 through the pump suction assembly.

[0045] During normal use, the protective sleeve 6 retracts and stores inside the protective cover 5. When dust accumulates on the surface of the high-voltage side terminal 2 and needs to be cleaned, the telescopic electromagnet 12 is energized, driving the first piston 13 to move up and down. The insulating oil in the oil storage sleeve 11 serves as the medium to provide power for the telescopic movement of the protective sleeve 6. When the protective sleeve 6 telescopically moves, it drives the internal brush bristles 7 to move up and down, cleaning the dust accumulated on the surface of the high-voltage side terminal 2. Because the low voltage of the telescopic electromagnet 12 has a sufficient safe distance from the high voltage of the transformer, the transformer can actively clean the dust without interrupting power, providing convenience for later maintenance.

[0046] When the flexible counterweight ring 9 is filled with insulating oil, the telescopic electromagnet 12 is de-energized, the weight of the flexible counterweight ring 9 increases, and the protective sleeve 6 is stretched downwards and extended, so that the protective sleeve 6 is kept covering the high-voltage side pile head 2, which plays a role in dust prevention and protection.

[0047] It should be noted that, without the telescopic electromagnet 12 providing power, to achieve the retraction of the protective sleeve 6, as follows: Figure 8 As shown, a force F3 needs to be applied to the first piston 13, and / or a force F4 needs to be applied to the second piston 16; as Figure 9 As shown, according to the principle of communicating vessels, F3 is equal to the weight of the insulating oil at a height of h in the conveying pipeline 10; F4 is the pressure of the insulating oil in the third chamber 17. For ease of understanding, the weight and friction of the first piston 13, the second piston 16, etc. are ignored here.

[0048] like Figure 8 As shown, when the oil pressure in tank 1 is less than F2, H2 is closed, and the insulating oil in tank 1 cannot enter the third chamber 17 through the connecting pipe 28. The volume of the third chamber 17 remains unchanged. If the second piston 16 is to move upward, the downward negative pressure force on the second piston 16 is much greater than F3 and F4. Therefore, the telescopic electromagnet 12 does not move, and the first piston 13 and the second piston 16 remain in the same position, so that the protective sleeve 6 can extend downward and maintain the state of covering the high-voltage side pile head 2.

[0049] When the transformer overheats due to factors such as faults or overload operation, the oil pressure in the oil tank 1 is greater than F2 because the pumping assembly is also equipped with a pressure relief sleeve 27. The insulating oil in the oil tank 1 enters the third chamber 17 through the connecting pipe 28. The pressure in the third chamber 17 increases, pushing the second piston 16 to move upward. At the same time, the first piston 13 moves upward, drawing the insulating oil in the flexible counterweight ring 9 back into the first chamber 14. This causes the protective sleeve 6 to retract and store in the protective cover 5. In other words, the protective sleeve 6 automatically changes from an unfolded state to a retracted state, which is beneficial for the heat dissipation of the exposed high-voltage side pile head 2 and further improves its safety.

[0050] The oil-immersed transformer proposed in this invention features a protective cover 5 and a protective sleeve 6 on the high-voltage side terminal 2. The protective sleeve 6 covers the outside of the high-voltage side terminal 2, providing excellent protection and dust prevention. The protective sleeve 6 can retract into the protective cover 5, exposing the high-voltage side terminal 2 for heat dissipation. This creates a better environment for protection and heat dissipation for the high-voltage side terminal 2 of the transformer, reducing the overheating failure rate. By providing independent protective sleeves 6 for each of the three high-voltage side terminals 2, the protection mechanisms of the three high-voltage side terminals 2 are independent of each other and have sufficient safety distance. Compared with placing each high-voltage terminal in the same dust cover, this design reduces the risk of flashover discharge between terminals, making it more reasonable and safer.

[0051] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An oil-immersed transformer with protective high-voltage terminals, comprising an oil tank (1), high-voltage side terminals (2), low-voltage side terminals (3), and an oil conservator (4), characterized in that: A protective cover (5) is fixedly installed on the upper end of the high-pressure side pile head (2). A telescopic protective sleeve (6) is fixedly installed inside the protective cover (5). Several bristles (7) are fixedly installed on the inner wall of the protective sleeve (6). The protective sleeve (6) covers the outside of the high-pressure side pile head (2), and the bristles (7) are in contact with the outer surface of the high-pressure side pile head (2). The surface of the protective sleeve (6) is embedded with a rubber tube (8), and a flexible counterweight ring (9) is fixedly installed on the lower side of the protective sleeve (6). The bottom end of the rubber tube (8) is connected to the inner cavity of the flexible counterweight ring (9). A pump suction assembly is fixedly installed inside the oil tank (1). The pump suction assembly stores insulating oil. A delivery pipeline (10) is installed inside the oil tank (1) and the high-voltage side pile head (2). The pump suction assembly is connected to the upper end of the rubber pipeline (8) through the delivery pipeline (10). When the pump suction assembly pumps the insulating oil into the flexible counterweight ring (9), the weight of the flexible counterweight ring (9) increases and stretches the protective sleeve (6) downward. When the pump suction assembly sucks the insulating oil back, the protective sleeve (6) shrinks and stores in the protective cover (5).

2. The oil-immersed transformer with protective features at the high-voltage pile head according to claim 1, characterized in that: The pump suction assembly includes an oil storage sleeve (11) and a telescopic electromagnet (12). The oil storage sleeve (11) is fixedly installed inside the oil tank (1). A first piston (13) is slidably installed inside the oil storage sleeve (11). The first piston (13) divides the inner cavity of the oil storage sleeve (11) into a first chamber (14) and a second chamber (15). The telescopic electromagnet (12) is fixedly installed on the upper side of the oil tank (1). The first piston (13) is driven to slide up and down by the telescopic electromagnet (12). The insulating oil is stored in the first chamber (14). The delivery pipeline (10) is connected to the first chamber (14).

3. The oil-immersed transformer with protective features at the high-voltage pile head according to claim 2, characterized in that: The pump suction assembly also includes a pressure relief sleeve (27), which is fixedly installed on the upper surface of the oil tank (1). A second piston (16) is slidably installed inside the pressure relief sleeve (27). The second piston (16) divides the inner cavity of the pressure relief sleeve (27) into a third chamber (17) and a fourth chamber (18). The third chamber (17) is connected to the inner cavity of the oil tank (1) through a connecting pipe (28) with a pressure relief valve (19). A pressure relief pipe (20) with a pressure relief valve (19) is fixedly installed on the outer wall of the pressure relief sleeve (27). The pressure relief pipe (20) is connected to the third chamber (17). A drive shaft (21) is fixedly installed between the first piston (13) and the second piston (16).

4. The oil-immersed transformer with protective features at the high-voltage pile head according to claim 3, characterized in that: The telescopic electromagnet (12) is fixedly installed at the top of the pressure relief sleeve (27). The telescopic end of the telescopic electromagnet (12) extends into the pressure relief sleeve (27) and is fixedly connected to the upper end face of the second piston (16). The drive shaft (21) slides through the top wall of the oil tank (1), and a sealing ring (22) is provided between the drive shaft (21) and the top wall of the oil tank (1).

5. An oil-immersed transformer with protective features at the high-voltage pile head according to claim 4, characterized in that: The insulating oil in the oil storage sleeve (11) and the insulating oil in the oil tank (1) are separated by the oil storage sleeve (11). When the insulating oil in the oil tank (1) is heated and expands, the insulating oil in the oil tank (1) enters the third chamber (17) through the connecting pipe (28). The pressure in the third chamber (17) increases, pushing the second piston (16) to move upward. At the same time, the first piston (13) moves upward, drawing the insulating oil in the flexible counterweight ring (9) back into the first chamber (14), causing the protective sleeve (6) to shrink and store in the protective cover (5). When the pressure in the third chamber (17) increases to a certain value, the pressure relief valve (19) automatically opens, and the insulating oil in the third chamber (17) is discharged through the pressure relief pipe (20).

6. An oil-immersed transformer with protective features at the high-voltage pile head according to claim 5, characterized in that: An overflow storage tank (23) is fixedly installed on the surface of the oil tank (1). The bottom end of the pressure relief pipe (20) extends into the overflow storage tank (23). A return pipe (24) is fixedly installed on the upper side of the overflow storage tank (23). The second chamber (15) and the fourth chamber (18) are connected to the overflow storage tank (23) through the return pipe (24).

7. An oil-immersed transformer with protective features at the high-voltage pile head according to any one of claims 1-6, characterized in that: The protective sleeve (6) is a corrugated rubber sleeve, and the protective cover (5) is made of epoxy resin material.

8. An oil-immersed transformer with protective features at high-voltage pile heads according to claim 7, characterized in that: A first magnetic ring (25) is fixedly installed on the lower side of the protective cover (5), and a second magnetic ring (26) is embedded inside the flexible counterweight ring (9). When the protective sleeve (6) is retracted and stored inside the protective cover (5), the first magnetic ring (25) and the second magnetic ring (26) are magnetically attracted.

9. An oil-immersed transformer with protective features at high-voltage pile heads according to claim 8, characterized in that: There are three high-voltage side pile heads (2), and each of the three high-voltage side pile heads (2) is equipped with a protective cover (5) and a protective sleeve (6). Insulating oil is pumped into the three protective sleeves (6) through the pump suction assembly.

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