An oil-immersed current transformer

Abstract

The application discloses an oil-immersed current transformer, and belongs to the technical field of inductors. The oil-immersed current transformer comprises an outer box, a sealed containing cavity is formed in the outer box, and the containing cavity is filled with heat dissipation oil. An induction main body comprises a primary winding, a secondary winding and a core, and the primary winding and the secondary winding are wound outside a core column of the core. The design of the outer box, the induction main body, a support, a circulator and a compensator is used for soaking the induction main body in the heat dissipation oil, spraying the heat dissipation oil along the core column of the core from bottom to top by the circulator, compensating heat dissipation for the position with serious heat generation, forming a circulating flow channel at the positions of the core, the primary winding and the secondary winding, and inhibiting the diffusion of air into the outer box by negative pressure while the compensator compensates the change of oil pressure, so that the emulsification and deterioration of the heat dissipation oil are avoided, and the stable heat dissipation is further ensured.

Description

Technical Field

[0001] This invention belongs to the field of inductor technology, specifically relating to an oil-immersed current transformer. Background Technology

[0002] A current transformer is a device based on the principle of electromagnetic induction, consisting of an iron core and windings. The primary winding has fewer turns and is connected in series in the circuit being measured. When current flows through it, it generates a magnetic field in the iron core. The secondary winding has more turns, and the magnetic field induces a current in the secondary winding that is proportional to the primary current. This design enables the conversion of large currents to small currents, facilitating measurement and protection, while also providing electrical isolation to ensure safety.

[0003] The existing Chinese utility model patent with publication number CN203910513U discloses an oil-immersed current transformer. When high temperatures are generated inside the oil-immersed current transformer, the presence of coolant will rapidly cool the inside of the oil tank through the casing and housing, preventing the oil tank from expanding, rupturing, and leaking oil. Furthermore, even if the oil tank expands, ruptures, and leaks oil, the presence of the cooler can prevent the oil leakage from occurring, ensuring the safety of electrical use. However, in response to the heating and expansion of the cooling oil, relying solely on cooling the external cooling oil cannot specifically cool the heat source (iron core and windings), resulting in a slow cooling rate. Consequently, with a fixed oil tank volume, the high-pressure state inside the oil tank will persist for a long time, increasing the probability of stress deformation and damage to the oil tank. In view of this, an oil-immersed current transformer is provided. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an oil-immersed current transformer.

[0005] The technical solution adopted to solve the above technical problems is:

[0006] An oil-immersed current transformer includes:

[0007] The outer casing has a sealed accommodating cavity inside, which is filled with heat dissipation oil.

[0008] The sensing body includes a primary winding, a secondary winding, and an iron core. The primary winding and the secondary winding are coiled around the outside of the iron core column. The two ends of the primary winding are respectively connected to a plate-shaped high-voltage terminal block through a connecting plate. The two ends of the secondary winding are respectively connected to a plate-shaped low-voltage terminal block through a connecting plate. The high-voltage terminal block and the low-voltage terminal block are located in a receiving cavity.

[0009] The support includes an upper frame and a lower frame, which are located on the outside of the yoke of the iron core. An upper flow channel is formed between the inner sidewall of the upper frame and the outer sidewall of the iron core, and a lower flow channel is formed between the inner sidewall of the lower frame and the outer sidewall of the iron core. A collecting shell is installed on the side of the lower frame facing the primary winding and the secondary winding. The collecting shell has a through hole at the iron core column corresponding to the iron core. An input shell is provided at the connection between the yoke and the iron core column of the collecting shell.

[0010] A circulator, the circulator including a pump, the output end of the pump being connected to the input shell via an output pipe;

[0011] The compensator is installed on the top of the outer casing. The compensator includes an inner shell with a compensation cavity. The bottom end of the compensation cavity communicates with the receiving cavity. A sliding member is slidably installed on the lower part of the inner side of the compensation cavity. A negative pressure pipe is installed on the top of the inner shell to keep the compensation cavity in a negative pressure state. An elastic member is installed between the top surface of the sliding member and the inner wall of the top of the inner shell.

[0012] During assembly, the pre-assembled sensor body is installed inside the bracket to form a single unit. The top cover of the outer casing is opened, and the unit is placed inside. The pump is fixed directly above the unit, and the outer casing is filled with cooling oil. The top cover of the outer casing is then replaced, and cooling oil is pumped into the outer casing to purge air and bring the cooling oil to a preset pressure range, completing the assembly. In use, the high-voltage and low-voltage terminal blocks serve as relays connecting the sensor body to the external circuit system. Utilizing a large-size flat plate structure, they ensure full contact with the cooling oil, addressing the issue of high localized heat generation due to high current density at the sensor body's input and output ends. Meanwhile, the circulator draws in and pressurizes the cooling oil at the bottom, flowing downwards... The flow channel cools the lower yoke of the iron core and sprays heat from bottom to top at the iron core column to dissipate heat from the primary and secondary windings. It also carries away the heat generated by hysteresis and eddy current losses at the iron core column. Finally, the heat-absorbing oil is horizontally dispersed to both sides at the upper flow channel, mixing with the heat-dissipating oil in the upper part of the outer casing to form a circulating flow channel that surrounds the iron core, primary winding, and secondary winding. As the temperature rises, the heat-dissipating oil expands, and the sliding parts are squeezed and push the elastic parts upward to compensate for the oil pressure changes inside the outer casing. At the same time, the amount of air in the negative pressure compensation chamber is small, which can prevent air from entering the outer casing and causing the heat-dissipating oil to emulsify. This ensures the working efficiency of the heat-dissipating oil while compensating for oil pressure changes.

[0013] Furthermore, the compensator also includes a guide member, the top of which is connected to the negative pressure pipe, a sliding sleeve is installed on the top of the sliding member, the lower part of the guide member is slidably inserted into the sliding sleeve, a horizontal hole is opened on the circumferential side wall of the sliding sleeve, and a vertical hole corresponding to the horizontal hole is opened on the lower part of the guide member.

[0014] Through the above technical solution, in order to optimize the installation relationship between the negative pressure pipe and the sliding sleeve, a guide is installed at the outlet end of the negative pressure pipe. The guide is larger than the opening on the top surface of the inner shell and is embedded in the opening of the inner shell to prevent air leakage due to the flexible deformation of the negative pressure pipe. The guide can also extend downward and slide together with the sliding sleeve on the same axis to play a vertical guiding role for the sliding part, preventing the sliding part from twisting and tilting during the up and down sliding process, ensuring the stability of the distance between the sliding part and the inner wall of the inner shell, and preventing uneven wear or jamming. The horizontal hole and the vertical hole cooperate to ensure the stable connection between the negative pressure pipe and the compensation cavity while the guide is coaxially sleeved with the sliding sleeve for guidance.

[0015] Furthermore, the guide member is provided with a rotary joint at the top, and an adjusting sleeve is rotatably sleeved on the outer side of the rotary joint. The outer circumferential wall of the adjusting sleeve is provided with threads, and the top of the inner shell is provided with a threaded hole that mates with the adjusting sleeve. A self-locking nut is screwed onto one end of the adjusting sleeve located on the outer side of the inner shell.

[0016] Through the above technical solution, in order to adapt to the characteristics of the elastic element, the initial position of the guide element can be changed by rotating the adjusting sleeve in the threaded hole under different oil pressures, thereby changing the initial compression force of the elastic element to adapt to different initial oil pressures in the outer casing, ensuring the consistency of the amount of cooling oil used, and avoiding the increase in production difficulty caused by different oil filling amounts of current transformers with different initial oil pressures.

[0017] Furthermore, a partition cylinder is provided between the through hole of the collecting shell and the bottom surface of the upper frame. The partition cylinder is sleeved on the outside of the iron core column of the iron core. An inner channel is formed between the inner circumferential wall of the partition cylinder and the vertical outer wall of the iron core. Ribs are installed along the axial direction on the outer circumferential wall of the partition cylinder. The primary winding and the secondary winding are coiled on the outside of the ribs. An outer channel is formed between the outer circumferential wall of the partition cylinder and the inner circumferential wall of the primary winding and the secondary winding.

[0018] Through the above technical solution, in order to optimize the flow path of the cooling oil, when it is sprayed upward along the through hole of the collecting shell, it will be blocked by the primary and secondary windings and dispersed in all directions. This results in less cooling oil being able to come into contact with the upper part of the iron core column. By guiding the flow through the partition cylinder, more cooling oil can rise to the top along the outer wall of the iron core column in the inner channel. At the same time, it can also rise along the outer channel to flush and dissipate heat from the inner edges of the primary and secondary windings. Moreover, the partition cylinder can also use ribs to spread the primary and secondary windings apart, increasing the distance between the coil windings and the iron core. Together with the partition cylinder and the cooling oil rising along the outer and inner channels, heat is blocked, reducing the impact of iron core heating on the primary and secondary windings and ensuring the stable operation of the primary and secondary windings.

[0019] Furthermore, the secondary winding includes an induction winding, which includes an outer coil wire group, a middle coil wire group, and an inner coil wire group. The outer coil wire group, the middle coil wire group, and the inner coil wire group are coaxially stacked and installed, with the middle coil wire group located between the outer coil wire group and the inner coil wire group. The outer coil wire group and the middle coil wire group are connected in series and fixed together by a connector, and the middle coil wire group and the inner coil wire group are connected in series and fixed together by a connector.

[0020] The above technical solution discloses a specific configuration of a secondary winding. The induction winding is designed in segments, with the outer coil, middle coil, and inner coil coil coaxially nested to form a multi-layer coil combination. They are connected in series through connector one and connector two. The total number of turns is much greater than the number of turns of the primary winding, so as to generate a smaller induced current. The outer coil and inner coil coil (inlet and outlet ends), which are prone to overheating due to high current density, are exposed to the outer layer and fully contact the heat dissipation oil to dissipate heat, ensuring the temperature stability of the inlet and outlet ends of the secondary winding.

[0021] Furthermore, a slot is provided on the side wall of the low-voltage terminal block, and the inner wall of the slot is provided with an insulating coating. The first terminal and the second terminal are insulated and fixedly installed in the slot.

[0022] Through the above technical solution, for the connection points of each section of the secondary winding, in order to compensate for heat dissipation, the connection points are tightened with bolts. The resistance of the connection points is relatively large compared with the overall coil resistance. By embedding terminal block one and terminal block two on the low-voltage terminal block, the heat of terminal block one and terminal block two can be transferred to the low-voltage terminal block. The large surface area of ​​the low-voltage terminal block enables efficient heat dissipation, avoiding abnormal temperature at the connection points. The insulating coating adopts a coating with strong thermal conductivity, which can improve the heat transfer efficiency while preventing short circuits.

[0023] Furthermore, the primary winding includes a high-voltage coil, which has a winding gap of uniform size along the radial direction.

[0024] The above technical solution discloses a specific configuration of the primary winding, in which the overall height of the high-voltage coil is consistent with the height of the secondary winding to fully cover the iron core column. However, the high-voltage coil has fewer turns, and a winding gap will be generated along the height direction after winding. This winding gap provides a bypass flow channel for the cooling oil, allowing more cooling oil to enter between the turns of the high-voltage coil, further improving the heat dissipation capacity of the high-voltage coil, and making it highly adaptable to the inductive heating of circuit systems with high voltage.

[0025] Furthermore, the iron core is constructed by stacking multiple layers of metal sheets, with the outer diameter of the metal sheets gradually decreasing from the middle to both sides, and the circumferential sidewalls of the iron core having stepped end faces.

[0026] Through the above technical solution, in order to ensure the heat dissipation efficiency of the iron core, the iron core is set in layers. The layered iron core significantly reduces heat generation by reducing eddy current and hysteresis losses, while improving the operating efficiency and safety of the equipment. Furthermore, the outer diameter of the metal sheet is designed to form a stepped end face, which effectively reduces the size of the iron core. This allows for an increase in the inner diameter of the upper and lower flow channels, enabling more cooling oil to flow along them. This, in turn, increases the heat dissipation efficiency of the iron core column, the inner edge of the primary winding, and the inner coil wire group. At the same time, the stepped end face also increases the surface area of ​​the iron core, further enhancing the cooling effect on the iron core.

[0027] Furthermore, the cross-sectional shape of the compensation cavity is a perfect circle, the sliding member adopts a perfect circular disk structure, multiple piston rings are embedded in the circumferential sidewall of the sliding member, the piston rings slide in contact with the inner circumferential wall of the compensation cavity, and an oil injection nozzle is installed on the sidewall of the outer casing.

[0028] Through the above technical solutions, in order to ensure the stability of the water volume and quality of the cooling oil, the perfect circular shape of the compensation chamber and the sliding parts has a higher degree of matching and a tighter joint. With the addition of piston rings, the overflow of cooling oil into the compensation chamber can be reduced, and air in the compensation chamber can be suppressed from entering the cooling oil. At the same time, because the compensation chamber is under negative pressure, the cooling oil tends to overflow into the compensation chamber. The cooling oil overflowing along the negative pressure pipe can be collected by the oil-air separator, and an equal amount of new oil can be added in time through the oil filling nozzle to ensure the stability of the cooling oil volume inside the outer casing.

[0029] Furthermore, the compensator also includes a housing with an opening at the bottom, the bottom of the housing being fastened to the opening at the top of the outer casing, fins on the outer wall of the housing, and a through hole at the top of the housing for the negative pressure pipe to pass through.

[0030] By optimizing the structure of the compensator through the above technical solution, since the heat-absorbing and cooling oil will accumulate on the top of the outer casing, in order to reduce the interference of temperature on the internal pressure of the inner casing, an outer shell is installed on the outside of the inner casing, and the fins are in contact with the outside air to supplement the cooling oil inside for heat dissipation. Combined with the circulation of the cooling oil, the temperature of the cooling oil is quickly reduced to a reasonable range.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) The present invention, through the design of outer casing, sensing body, bracket, circulator and compensator, immerses the sensing body in heat dissipation oil, and uses the circulator to spray the heat dissipation oil from bottom to top along the iron core column of the iron core, to compensate for heat dissipation in the severely heated position, and forms a circulation channel at the iron core, primary winding and secondary winding position. While compensating for oil pressure changes, the compensator suppresses the diffusion of air into the outer casing through negative pressure, avoids emulsification and deterioration of heat dissipation oil, and further ensures stable heat dissipation.

[0033] (2) By improving the compensator, the present invention uses the guide to vertically guide the sliding part, ensuring that the contact between the sliding part and the inner shell is stable and centered, reducing the phenomenon of uneven wear and tilting jamming, preventing the heat dissipation oil from overflowing through the sliding part, and using the guide to stably connect the negative pressure pipe to the top of the inner shell, ensuring that the inner shell can be stably in a negative pressure state, and using the adjusting sleeve to change the initial position of the sliding part and the initial pressure of the elastic part, adapting to current transformers with different initial oil pressure states.

[0034] (3) The present invention, through the design of the partition cylinder, allows more heat dissipation oil to rise along the outer wall of the iron core column in the inner channel position, and also along the outer channel to flush and dissipate heat on the inner edge of the primary winding and the secondary winding. In conjunction with the partition cylinder and the heat dissipation oil rising along the outer and inner channels, heat is blocked, reducing the impact of iron core heating on the primary winding and the secondary winding, and ensuring that the temperature between the inner and outer edges of the primary winding and the secondary winding is uniform and stable. Attached Figure Description

[0035] Figure 1 This is a first-view structural diagram of the present invention;

[0036] Figure 2 This is a structural schematic diagram of the outer casing of the present invention in a cross-sectional state;

[0037] Figure 3 This is a schematic diagram showing the positions of the primary winding, secondary winding, support, circulator, and compensator of the present invention.

[0038] Figure 4 This is a schematic diagram showing the positions of the primary winding, secondary winding, support, and circulator of the present invention;

[0039] Figure 5 This is a cross-sectional schematic diagram showing the relationship between the primary winding, secondary winding, support, and circulator of the present invention;

[0040] Figure 6 This is a schematic diagram of the structure between the primary winding, the secondary winding, and the support of the present invention;

[0041] Figure 7 This is a schematic diagram showing the disassembled relationship between the primary winding, the secondary winding, and the support of the present invention;

[0042] Figure 8 This is a bottom view of the primary winding, secondary winding, and support structure of the present invention;

[0043] Figure 9 This is a schematic diagram of the compensator of the present invention in a cross-sectional state;

[0044] Figure 10 This is a schematic diagram showing the split of the secondary winding of the present invention.

[0045] Reference numerals: 1. Outer casing; 2. Primary winding; 21. High-voltage coil; 22. High-voltage terminal block; 23. Winding gap; 3. Secondary winding; 31. Induction winding; 311. Outer coil group; 312. Middle coil group; 313. Inner coil group; 32. Low-voltage terminal block; 33. Slot; 34. Connecting plate; 35. Terminal block one; 36. Terminal block two; 4. Compensator; 41. Inner shell; 411. Compensation cavity; 412. Threaded hole; 42. Negative pressure pipe; 43. Outer shell; 44. Sliding component; 441. Sliding sleeve; 442. Horizontal hole; 443. Piston ring; 45. Guide component; 451, vertical hole; 452, screw connector; 46, adjusting sleeve; 461, self-locking nut; 47, elastic component; 5, circulator; 51, pump; 52, output pipe; 53, input pipe; 6, terminal block; 7, bracket; 71, upper frame; 711, upper flow channel; 72, lower frame; 721, lower flow channel; 73, collecting shell; 731, inclined top edge; 74, input shell; 75, base; 77, lug; 78, support frame; 79, through screw; 8, iron core; 81, stepped end face; 9, partition cylinder; 91, outer channel; 92, inner channel; 93, rib. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] like Figures 1-10 As shown, this embodiment provides an oil-immersed current transformer. To improve the problems existing in the current oil-immersed transformer, and addressing the issue of poor heat dissipation of the iron core column 8 causing excessively high inner temperature of the coil winding that is difficult to dissipate, a specific configuration is provided for improvement:

[0048] Regarding outer box 1, refer to... Figure 1 and Figure 2 The outer casing 1 forms a sealed accommodating cavity, which is filled with cooling oil.

[0049] Regarding the sensing subject, refer to... Figure 3 and Figure 6 The sensing body includes a primary winding 2, a secondary winding 3 and an iron core 8. The primary winding 2 and the secondary winding 3 are coiled on the outside of the iron core column of the iron core 8. The two ends of the primary winding 2 are respectively connected to a plate-shaped high-voltage terminal block 22 through a step plate 34. The two ends of the secondary winding 3 are respectively connected to a plate-shaped low-voltage terminal block 32 through a step plate 34. The high-voltage terminal block 22 and the low-voltage terminal block 32 are located in the accommodating cavity.

[0050] Regarding bracket 7, refer to... Figure 4 and Figure 5The bracket 7 includes an upper frame 71 and a lower frame 72. The upper frame 71 and the lower frame 72 are located on the outside of the iron core 8. The upper frame 71 and the lower frame 72 are clamped to the iron core 8 by through screws 79. The lugs 77 are located on the vertical outer walls of the upper frame 71 and the lower frame 72 to provide stable support for the high voltage terminal block 22 and the low voltage terminal block 32. An upper flow channel 711 is formed between the inner wall of the upper frame 71 and the outer wall of the iron core 8. A lower flow channel 721 is formed between the inner wall of the lower frame 72 and the outer wall of the iron core 8. A base 75 is installed at the bottom of the lower frame 72 to ensure that the position of the bracket 7 is vertical and stable. A collection shell 73 is installed on the side of the lower frame 72 facing the first-stage winding 2 and the second-stage winding 3. The collection shell 73 has a through hole at the iron core column of the iron core 8. An input shell 74 is provided at the connection between the iron core column and the iron core column of the collection shell 73.

[0051] Regarding looper 5, see [reference] Figure 4 The circulator 5 includes a pump 51, and a support 78 is provided on the top of the upper frame 71 to facilitate the installation of the pump 51. The output end of the pump 51 is connected to the input shell 74 through the output pipe 52.

[0052] Regarding compensator 4, refer to... Figure 9 The compensator 4 is installed on the top of the outer casing 1. The compensator 4 includes an inner shell 41 with a compensation cavity 411. The bottom end of the compensation cavity 411 communicates with the accommodating cavity. A sliding member 44 is slidably installed on the lower inner side of the compensation cavity 411. A negative pressure pipe 42 is installed on the top of the inner shell 41 to keep the compensation cavity 411 in a negative pressure state. An elastic member 47 is installed between the top surface of the sliding member 44 and the inner wall of the top of the inner shell 41.

[0053] The working principle of this embodiment is as follows:

[0054] During assembly, the pre-assembled sensor body is installed in the bracket 7 to form an integral part. The top cover of the outer box 1 is opened, and the integral part is placed inside the outer box 1. The pump 51 is fixed directly above the integral part to fill the interior of the outer box 1 with cooling oil. The top cover of the outer box 1 is then reinstalled, and cooling oil is filled into the outer box 1 to purge the air inside the outer box 1 and bring the cooling oil to a preset oil pressure range. The high-voltage terminal block 22 and the low-voltage terminal block 32 extend to the outside of the outer box 1 using the terminal block 6 to complete the assembly.

[0055] In use, the high-voltage terminal block 22 is connected to the power system to receive high-voltage current, while the low-voltage terminal block 32 is connected to the measuring instrument to generate low-voltage detection current. The high-voltage terminal block 22 and the low-voltage terminal block 32 serve as relays connecting the sensing body to the external circuit system. By utilizing the large-size flat plate structure to fully contact the heat dissipation oil, targeted cooling is provided to address the phenomenon of high local heat generation due to the large current density at the inlet and outlet of the sensing body.

[0056] To dissipate heat, refer to Figure 2 and Figure 4The oil inlet of the circulator 5 is equipped with an input pipe 53. The lower end of the input pipe 53 is close to the bottom surface of the outer casing 1. It draws and pressurizes the cooling oil at the bottom and sends it into the input shell 74 through the output pipe 52. It flows horizontally from both ends to the middle along the lower flow channel 721 to cool the iron yoke at the bottom of the iron core 8. Under the guidance of the collecting shell 73, it is sprayed from bottom to top along the iron core column of the iron core 8 to cool the primary winding 2 and the secondary winding 3. It can also carry away the heat generated by hysteresis loss and eddy current loss at the iron core column of the iron core 8. Finally, the cooling oil after absorbing heat is horizontally scattered to both sides at the upper flow channel 711 and mixed with the cooling oil in the upper part of the inner side of the outer casing 1 to form a circulation channel that wraps the iron core 8, the primary winding 2 and the secondary winding 3.

[0057] As temperature rises, reference Figure 3 and Figure 9 The negative pressure pipe 42 is connected to the air extraction device to put the compensation chamber 411 in a negative pressure state. The elastic element 47 is compressed to resist the pressure difference and finally make the sliding element 44 stationary in the compensation chamber 411. When the heat dissipation oil heats up and causes the internal pressure to rise, the dynamic balance of the sliding element 44 will be disrupted. The increase in internal pressure will push the elastic element 47 upward, increasing the volume of the outer box 1 and compensating for the oil pressure change inside the outer box 1. At the same time, the amount of air in the compensation chamber 411 under negative pressure is less. Compared with the compensation chamber in the conventional compensator, which is directly connected to the external atmosphere, the compensation chamber in the conventional compensator will contain atmospheric pressure air. This negative pressure state or vacuum state can prevent air from entering the outer box 1 and causing the heat dissipation oil to emulsify. After the heat dissipation oil emulsifies, it will obstruct the contact with the iron core 8, the primary winding 22 and the secondary winding 3. Therefore, the emulsification of the heat dissipation oil is suppressed. While compensating for the oil pressure change, the working efficiency of the heat dissipation oil can be guaranteed.

[0058] In a further embodiment, to optimize the installation relationship between the negative pressure pipe 42 and the sliding sleeve 441, refer to Figure 9 The compensator 4 also includes a guide 45, which is installed at the outlet end of the negative pressure pipe 42. The guide 45 is larger than the opening on the top surface of the inner shell 41 and is embedded in the opening of the inner shell 41 to prevent air leakage due to the flexible deformation of the negative pressure pipe 42. The guide 45 can also extend downwards, and its top is connected to the negative pressure pipe 42. A sliding sleeve 441 is installed on the top of the sliding member 44, and the lower part of the guide 45 is slidably inserted into the sliding sleeve 441, which serves as a vertical guide for the sliding member 44. The function is to prevent the sliding member 44 from twisting or tilting during the up and down sliding process, and to ensure the stability of the distance between the sliding member 44 and the inner wall of the inner shell 41 to avoid uneven wear or jamming. Furthermore, the circumferential side wall of the sliding sleeve 441 is provided with a horizontal hole 442, and the lower part of the guide member 45 is provided with a vertical hole 451 corresponding to the horizontal hole 442. The horizontal hole 442 and the vertical hole 451 cooperate to ensure stable communication between the negative pressure pipe 42 and the compensation cavity 411 while the guide member 45 and the sliding sleeve 441 are coaxially sleeved for guidance.

[0059] In a further embodiment, to accommodate the inherent characteristics of the elastic element 47, refer to Figure 9 The guide member 45 has a rotary joint 452 at its top, and an adjusting sleeve 46 is rotatably sleeved on the outside of the rotary joint 452. The outer circumference of the adjusting sleeve 46 is threaded, and the top of the inner shell 41 has a threaded hole 412 that mates with the adjusting sleeve 46. Based on different oil pressures, the initial position of the guide member 45 can be changed by rotating the adjusting sleeve 46 within the threaded hole 412. Because of the lower edge position of the sliding member 44, the bottom of the inner shell 41 is inwardly contracted and equipped with a limiting retaining ring with an inner diameter smaller than the outer edge of the sliding member 44. The sliding member 44 cannot slide out of the compensation cavity 411 from the bottom. Therefore, the downward movement of the adjusting sleeve 46 can increase the initial compression force of the elastic member 47, adapting to the larger initial oil pressure inside the outer casing 1. If the initial oil pressure is low, rotate the adjusting sleeve 46 upward to reduce the initial compression force of the elastic element 47, ensuring consistent cooling oil usage after filling. This avoids increased production difficulty caused by different initial oil pressures in the current transformers. Furthermore, if the elastic element 47 experiences stress fatigue and shortens in length during use, the downward movement of the adjusting sleeve 46 can compensate for the shortened length, ensuring the initial position of the sliding element 44 remains stable. A self-locking nut 461 is screwed onto one end of the adjusting sleeve 46 located outside the inner shell 41. Tightening the self-locking nut 461 after adjustment ensures stable positioning during operation and prevents the adjusting sleeve 46 from disengaging from the threaded hole 412.

[0060] In a further embodiment, to optimize the flow path of the cooling oil, refer to Figure 5 , Figure 7 and Figure 8A partition cylinder 9 is provided between the through hole of the collecting shell 73 and the bottom surface of the upper frame 71. When the oil is sprayed upward along the through hole of the collecting shell 73, it is blocked by the primary winding 2 and the secondary winding 3 and dispersed in all directions. This results in less flowing cooling oil being able to contact the upper part of the iron core column of the iron core 8. The oil is guided by the partition cylinder 9. The partition cylinder 9 is sleeved on the outside of the iron core column of the iron core 8. An inner channel 92 is formed between the inner circumference of the partition cylinder 9 and the vertical outer wall of the iron core 8. This allows more cooling oil to rise to the top along the outer wall of the iron core column of the iron core 8 at the position of the inner channel 92 and smoothly enter the upper flow channel 711. Ribs 93 are installed axially on the outer circumference of the partition cylinder 9. The primary winding 2 and the secondary winding 3 are coiled on the outside of the ribs 93. The outer circumference of the partition cylinder 9 and the inner circumference of the primary winding 2 and the secondary winding 3 are connected. An outer channel 91 is formed between the walls, allowing the cooling oil to flow upwards along the outer channel 91 and flush the inner edges of the primary winding 2 and the secondary winding 3 for heat dissipation. It is worth emphasizing that, to accommodate the spiral shape of the primary winding 2 and the secondary winding 3, the top of the collecting shell 73 is designed as a sloping top edge 731, which fits fully against the bottom of the primary winding 2 and the secondary winding 3, reducing the overflow of cooling oil in this area. In addition, the partition cylinder 9 can also use the ribs 93 to spread the primary winding 2 and the secondary winding 3 apart, increasing the distance between the coil winding and the iron core 8. Together with the partition cylinder 9 and the cooling oil flowing upwards along the outer channel 91 and the inner channel 92, heat is blocked, reducing the impact of the heating of the iron core 8 on the primary winding 2 and the secondary winding 3, and ensuring the stable operation of the primary winding 2 and the secondary winding 3.

[0061] In a further embodiment, a specific configuration of the secondary winding 3 is disclosed, referring to... Figure 7 and Figure 10 The secondary winding 3 includes an induction winding 31. The induction winding 31 has a segmented design, allowing for individual replacement of easily damaged input and output terminals. This segmented design also optimizes the location of the input and output terminals. Specifically, the induction winding 31 includes an outer coil group 311, a middle coil group 312, and an inner coil group 313, connected in series via connector 35 and connector 36 to form a multi-layer coil combination. The total number of turns is much greater than that of the primary winding 2, thus generating a smaller induced current. The outer coil group 311, the middle coil group 312, and the inner coil group 313 are... The middle coil 312 and the inner coil 313 are coaxially sleeved. The middle coil 312 is located between the outer coil 311 and the inner coil 313. The outer coil 311 and the inner coil 313 (inlet and outlet ends), which are prone to overheating due to high current density, are exposed to the outermost and innermost layers. The outermost layer can directly contact the heat dissipation oil in the outer casing 1, and the innermost layer can directly contact the heat dissipation oil flowing at the outer channel 91. The inlet and outlet ends of the secondary winding 3 can fully contact the heat dissipation oil to dissipate heat, ensuring the coil temperature is stable in the location prone to overheating.

[0062] In a further embodiment, at the connection points of each segment of the secondary winding 3, bolts are used to tighten the connections for heat dissipation compensation. The resistance at the connection points is relatively large compared to the overall coil resistance. (Refer to...) Figure 10 A slot 33 is provided on the side wall of the low-voltage terminal block 32. The first connector 35 and the second connector 36 are insulated and fixedly installed in the slot 33. The first connector 35 and the second connector 36 are embedded in the low-voltage terminal block 32, which has a larger contact area. The heat of the first connector 35 and the second connector 36 can be transferred to the low-voltage terminal block 32. The large surface area of ​​the low-voltage terminal block 32 can be used for efficient heat dissipation and avoid abnormal temperature at the connection. The inner wall of the slot 33 is provided with an insulating coating. The insulating coating is a coating with strong thermal conductivity, which can improve the heat transfer efficiency while preventing short circuits.

[0063] In a further embodiment, a specific configuration of the primary winding 2 is disclosed, referring to... Figure 6 The primary winding 2 includes a high-voltage coil 21. The overall height of the high-voltage coil 21 is the same as that of the secondary winding 3 to fully cover the core column of the core 8. However, the high-voltage coil 21 has fewer turns, and after winding, a winding gap 23 will be generated along the height direction. This winding gap 23 provides a bypass flow channel for the cooling oil, allowing more cooling oil to enter between the turns of the high-voltage coil 21, further improving the heat dissipation capacity of the high-voltage coil 21, and making it highly adaptable to the inductive heating of circuit systems with high voltage.

[0064] In a further embodiment, to ensure the heat dissipation efficiency of the iron core 8, refer to Figure 7 The iron core 8 is constructed using a multi-layered metal sheet stacking arrangement. This layered iron core significantly reduces heat generation by minimizing eddy current and hysteresis losses, while simultaneously improving the operating efficiency and safety of the equipment. Furthermore, the outer diameter of the metal sheets gradually decreases from the center to both sides. The design of the outer diameter of the metal sheets creates a stepped end face 81, which effectively reduces the size of the iron core. This increases the inner diameter of the upper flow channel 711 and the lower flow channel 721, allowing more cooling oil to flow along them. This, in turn, increases the heat dissipation efficiency of the iron core column, the inner edge of the primary winding 2, and the inner coil wire group 313. In addition, the stepped end face 81 formed on the circumferential sidewall of the iron core 8 further increases the surface area of ​​the iron core 8, thereby enhancing the cooling effect on the iron core 8.

[0065] In a further embodiment, to ensure the stability of the water quantity and quality of the cooling oil, refer to Figure 9The cross-sectional shape of the compensation cavity 411 is a perfect circle, and the sliding member 44 adopts a perfect circular disk structure. The perfect circular shape of the compensation cavity 411 and the sliding member 44 results in a higher degree of matching and a tighter joint. Multiple piston rings 443 are embedded in the circumferential side wall of the sliding member 44. The piston rings 443 slide in contact with the inner circumferential wall of the compensation cavity 411. With the addition of the piston rings 443, the overflow of heat dissipation oil into the compensation cavity 411 can be reduced, and air in the compensation cavity 411 can be prevented from entering the heat dissipation oil. An oil filling nozzle is installed on the side wall of the outer casing 1. Because the compensation cavity 411 is under negative pressure, the heat dissipation oil tends to overflow into the compensation cavity 411. The heat dissipation oil overflowing along the negative pressure pipe 42 can be collected by the oil-gas separator, and an equal amount of new oil can be added in time through the oil filling nozzle to ensure a stable amount of heat dissipation oil inside the outer casing 1.

[0066] In a further embodiment, the structure of compensator 4 is optimized, referring to... Figure 1 and Figure 9 Because the heat-absorbing cooling oil will accumulate at the top of the outer casing 1, in order to reduce the interference of temperature on the internal pressure of the inner casing 41, an outer casing 43 is installed on the outside of the inner casing 41. The bottom of the outer casing 43 has an opening, and the bottom of the outer casing 43 is fastened to the opening at the top of the outer casing 1, so that the oil in the upper part of the inner side of the outer casing 1 can directly enter the outer casing 43. The outer wall of the outer casing 43 is provided with fins, which contact the outside air through the fins to replenish and dissipate heat from the internal cooling oil. With the circulation of the cooling oil, the temperature of the cooling oil is quickly reduced to a reasonable range. It should be noted that an overflow valve is installed at the highest point of the outer casing 43. When filling the outer casing 1 with cooling oil, all the air in the outer casing 43 can be extracted through the overflow valve to ensure that the space inside the outer casing 1 is filled with cooling oil. The top of the outer casing 43 has a through hole for the negative pressure pipe 42 to pass through, so as not to obstruct the movement and installation of the negative pressure pipe 42.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. An oil-immersed current transformer, characterized in that, include: The outer casing (1) has a sealed accommodating cavity inside, which is filled with heat dissipation oil. The sensing body includes a primary winding (2), a secondary winding (3) and an iron core (8). The primary winding (2) and the secondary winding (3) are coiled around the outside of the iron core column of the iron core (8). The two ends of the primary winding (2) are respectively connected to a plate-shaped high-voltage terminal block (22) through a step plate (34). The two ends of the secondary winding (3) are respectively connected to a plate-shaped low-voltage terminal block (32) through a step plate (34). The high-voltage terminal block (22) and the low-voltage terminal block (32) are located in the accommodating cavity. The bracket (7) includes an upper frame (71) and a lower frame (72). The upper frame (71) and the lower frame (72) are located on the outside of the iron core (8). An upper flow channel (711) is formed between the inner wall of the upper frame (71) and the outer wall of the iron core (8). A lower flow channel (721) is formed between the inner wall of the lower frame (72) and the outer wall of the iron core (8). A collection shell (73) is installed on the side of the lower frame (72) facing the first-stage winding (2) and the second-stage winding (3). The collection shell (73) has a through hole at the iron core column of the iron core (8). An input shell (74) is provided at the connection between the iron core column and the iron core column of the collection shell (73). The circulator (5) includes a pump (51), the output end of which is connected to the input shell (74) through an output pipe (52); The compensator (4) is installed on the top of the outer casing (1). The compensator (4) includes an inner shell (41) with a compensation cavity (411). The bottom end of the compensation cavity (411) is connected to the accommodating cavity. A sliding member (44) is slidably installed on the lower inner side of the compensation cavity (411). A negative pressure pipe (42) is installed on the top of the inner shell (41) to make the compensation cavity (411) be in a negative pressure state. An elastic member (47) is installed between the top surface of the sliding member (44) and the inner wall of the top of the inner shell (41). The compensator (4) also includes a guide (45), the top of which is connected to the negative pressure pipe (42). A sliding sleeve (441) is installed on the top of the sliding member (44), and the lower part of the guide (45) is slidably inserted into the sliding sleeve (441). A horizontal hole (442) is opened on the circumferential side wall of the sliding sleeve (441), and a vertical hole (451) corresponding to the horizontal hole (442) is opened on the lower part of the guide (45). The guide (45) is provided with a screw joint (452) at the top. An adjusting sleeve (46) is rotatably sleeved on the outside of the screw joint (452). The outer circumference of the adjusting sleeve (46) is provided with threads. The top of the inner shell (41) is provided with a threaded hole (412) that mates with the adjusting sleeve (46). A self-locking nut (461) is screwed onto one end of the adjusting sleeve (46) located on the outside of the inner shell (41).

2. The oil-immersed current transformer according to claim 1, characterized in that, A partition cylinder (9) is provided between the through hole of the collection shell (73) and the bottom surface of the upper frame (71). The partition cylinder (9) is sleeved on the outside of the iron core column of the iron core (8). An inner channel (92) is formed between the inner circumference of the partition cylinder (9) and the vertical outer wall of the iron core (8). Ribs (93) are installed on the outer circumference of the partition cylinder (9) along the axial direction. The primary winding (2) and the secondary winding (3) are coiled on the outside of the ribs (93). An outer channel (91) is formed between the outer circumference of the partition cylinder (9) and the inner circumference of the primary winding (2) and the secondary winding (3).

3. The oil-immersed current transformer according to claim 2, characterized in that, The secondary winding (3) includes an induction winding (31), which includes an outer coil wire group (311), a middle coil wire group (312), and an inner coil wire group (313). The outer coil wire group (311), the middle coil wire group (312), and the inner coil wire group (313) are coaxially stacked and installed, with the middle coil wire group (312) located between the outer coil wire group (311) and the inner coil wire group (313). The outer coil wire group (311) and the middle coil wire group (312) are connected in series and fixed through a connector one (35). The middle coil wire group (312) and the inner coil wire group (313) are connected in series and fixed through a connector two (36).

4. The oil-immersed current transformer according to claim 3, characterized in that, The low-voltage terminal block (32) has a slot (33) on its side wall. The inner wall of the slot (33) is provided with an insulating coating. The first terminal (35) and the second terminal (36) are insulated and fixedly installed in the slot (33).

5. The oil-immersed current transformer according to claim 2, characterized in that, The primary winding (2) includes a high-voltage coil (21), and the high-voltage coil (21) has a winding gap (23) of uniform size along the radial direction.

6. The oil-immersed current transformer according to claim 1, characterized in that, The iron core (8) is made of multiple layers of metal sheets stacked together. The outer diameter of the metal sheets gradually decreases from the middle to both sides. The circumferential sidewall of the iron core (8) has a stepped end face (81).

7. The oil-immersed current transformer according to claim 1, characterized in that, The cross-sectional shape of the compensation cavity (411) is a perfect circle, the sliding member (44) adopts a perfect circular disk structure, and multiple piston rings (443) are embedded in the circumferential sidewall of the sliding member (44). The piston rings (443) slide in contact with the inner circumferential wall of the compensation cavity (411).

8. The oil-immersed current transformer according to claim 1, characterized in that, The compensator (4) also includes a housing (43), the bottom of which has an opening, the bottom of which is fastened to the top opening of the outer box (1), the outer wall of which has fins, and the top of which has a through hole for the negative pressure pipe (42) to pass through.

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