Oil-immersed power transformer

Abstract

The invention relates to the technical field of power transformers, in particular to an oil-immersed power transformer which comprises an oil conservator, an oil tank, a cooler, a wire outlet end, a transformer body, a supporting frame, a bottom plate and a filter, connecting bases are arranged in front of the oil tank and are paired up and down, the cooler comprises a through pipe and fins, the through pipe is installed on the connecting bases, and the fins are installed on the through pipe. The multiple fins are arranged between each pair of through pipes, the transformer body comprises an iron core, a high-voltage winding, a low-voltage winding, oiled paper, an inner plate and an outer plate, the iron core is located above the inner bottom of the oil tank, the oiled paper is located between the low-voltage winding and the high-voltage winding, the inner plate is located on the inner side of the low-voltage winding, and the outer plate is located on the outer side of the high-voltage winding; according to the invention, impurities are collected through an insulating part specially designed on the winding, and the impurities are intensively discharged to the filtering device, so that the dispersion of the impurities in oil is avoided, and the purpose of rapidly removing the impurities is further achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power transformers, in particular to an oil-immersed power transformer. Background Art

[0002] A power transformer is a device that converts high-voltage (or low-voltage) electrical energy into low-voltage (or high-voltage) electrical energy through electromagnetic induction. To ensure the insulation performance inside the equipment, the transformer is often filled with gas, liquid or solid insulating media. Liquid has better insulation performance than gas and lower cost than solid. Therefore, liquid is often the first choice as the transformer filling medium. Therefore, oil-immersed power transformers are very common.

[0003] Oil-immersed power transformers generate heat during operation. To ensure the normal operation of the equipment, a cooling system is often provided. According to the cooling method, oil-immersed power transformers can be divided into natural oil circulation cooling and forced oil circulation cooling. The former uses the principle of hot and cold convection of liquid to allow the high-temperature oil floating on the upper surface to naturally enter the cooling device, and after cooling, it is discharged to the bottom by the cooling device; the latter is based on the original equipment and an additional oil pump is provided. The oil is driven by the oil pump to circulate inside the cooling device and cool down; in comparison, the latter has better cooling performance, but is also more expensive, so it is often used in special occasions. Accordingly, the former is more commonly used. The present invention improves the natural oil circulation cooling power transformer.

[0004] When current passes through the windings inside the transformer, a large amount of heat is generated. At the moment of heat generation, the high temperature will cause the oil around the windings to oxidize and produce impurities. As the equipment working hours increase, the impurities will continue to accumulate and disperse in the oil, thereby reducing the oil content and affecting the insulation and cooling performance of the oil. Therefore, the existing technology often arranges a filtering device to remove impurities. For example, in an oil-immersed power transformer with publication number CN111710504B, the oil tank, the segmented impurity separation structure, and the oil pump are connected in series, so that the oil in the oil tank is continuously circulated in the segmented impurity separation structure, thereby ensuring the purity of the oil and ensuring the insulation and cooling performance of the oil.

[0005] Natural oil circulation cooling power transformers can also be equipped with filtering devices to filter the oil before it enters the cooling device. However, compared with forced circulation, the oil circulation speed of natural circulation is lower and uncontrollable, so the efficiency of removing impurities is lower. Accordingly, impurities that cannot be removed in time will have a continuous negative impact on the insulation and cooling performance of the oil.

[0006] In order to improve the efficiency of removing impurities, an oil-immersed power transformer is proposed. Summary of the Invention

[0007] The object of the present invention is to provide an oil-immersed power transformer, which solves the problem of low impurity removal efficiency of natural oil circulation cooling power transformers. Impurities are collected by specially designed insulating components on the windings and discharged to a filtering device, thereby avoiding the dispersion of impurities in the oil and achieving the purpose of rapid impurity removal.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] An oil-immersed power transformer comprises an oil pillow, an oil tank, a cooler, an outlet terminal, a transformer body, a support frame, a bottom plate, and a filter. A connecting seat is arranged in front of the oil tank, and the connecting seats are paired up and down. The cooler comprises a through pipe and fins. The through pipe is mounted on the connecting seat, and a plurality of fins are arranged between each pair of through pipes. The transformer body comprises an iron core, a high-voltage winding, a low-voltage winding, oil paper, an inner plate, and an outer plate. The iron core is located above the inner bottom of the oil tank. The low-voltage winding and the high-voltage winding are wound around the iron core in sequence from the inside to the outside. The oil paper is located between the low-voltage winding and the high-voltage winding. The inner plate is located inside the low-voltage winding, and the outer plate is located outside the high-voltage winding. The interior of the outer plate is connected to the connecting seat above. The filter is mounted on the protruding side of the through pipe.

[0010] The inner plate and the outer plate are clamped together to form an enclosure for the upper side and peripheral surface of the high-voltage winding and the low-voltage winding. The filter absorbs impurities in the high-temperature oil discharged from the inside of the inner plate and the outer plate to the through pipe, and the purified high-temperature oil is cooled by the fins and then guided back to the bottom of the oil tank through the through pipe below.

[0011] To save space and improve electromagnetic utilization, the high-voltage and low-voltage windings in transformers are often coaxially wound on the iron core. This requires ensuring insulation between the high-voltage and low-voltage windings, so oil-paper is usually arranged between the two. The low-voltage and high-voltage windings fit tightly against the oil-paper. Therefore, when current passes through the windings, the heat generated will accumulate, accelerating the oxidation of the oil, which in turn leads to the generation of a large amount of impurities.

[0012] Preferably, ridges are provided on both sides of the oil paper, and the ridges are arranged at equal intervals;

[0013] In the above scheme, the arrangement of the ridges, on the one hand, leaves gaps between the high-voltage winding and the low-voltage winding and the oil paper, thereby facilitating the flow of oil and promptly taking away the heat generated by the windings when they are working; on the other hand, the setting of the ridges increases the contact area between the oil paper and the oil, thereby improving the heat dissipation performance of the oil paper, thereby further absorbing the heat generated by the windings.

[0014] Copper loss in the high-voltage and low-voltage windings is the core reason for transformer temperature rise. The oil near the windings is most susceptible to oxidation and the generation of impurities. The oil in the oil tank is fluid, and impurities generated near the windings will gradually spread throughout the tank. Although the oil is purified by the filter device while cooling through natural circulation, the speed of natural circulation is low and unstable, resulting in low purification efficiency and slow impurity removal. Residual impurities will have a lasting negative impact.

[0015] Preferably, the upper end of the outer plate is bent inward, and the upper portion of the inner plate is clamped to the bent portion of the outer plate;

[0016] In the above scheme, a semi-enclosed space with an opening facing downward is formed by the clamping of the inner plate and the outer plate, and the high-voltage winding and the low-voltage winding are both located inside this space, thereby producing the following effects: 1) The oil in the semi-enclosed space floats due to heat and is directly discharged to the cooler. During the floating process, it does not directly contact the oil outside the outer plate, thereby directly bringing a large amount of heat out of the oil tank, thereby improving the cooling effect of the transformer; 2) Impurities generated by the oxidation of the oil in the semi-enclosed space will enter the cooler together with the floating of the oil, and will not spread to various parts of the oil tank, and will be filtered and removed in this process; 3) The oil surface is a place where bubbles are easily gathered, and high-voltage discharge is prone to occur. Through the cover of the semi-enclosed space, the insulation capacity of the winding electric energy is further improved, thereby reducing the probability of high-voltage discharge.

[0017] Preferably, the inner wall of the upper portion of the outer plate is in contact with the high-voltage winding, and the inner diameter of the lower portion of the outer plate gradually increases from top to bottom;

[0018] In the above scheme, the inner diameter of the lower part of the outer plate gradually increases from top to bottom in order to facilitate the oil at the bottom of the oil tank to enter the semi-enclosed space inside the outer plate, and by reducing the diameter, the speed of the oil entering the semi-enclosed space is gradually increased to carry impurities into the upper part of the semi-enclosed space; and the setting of the upper part of the outer plate makes the high-voltage winding fit against the inner wall, which on the one hand makes the installation of the outer plate more stable, and on the other hand blocks the channel for impurities to flow back, so that the impurities are concentrated inside the outer plate.

[0019] High-voltage power transmission is usually carried out in the form of three-phase power. Therefore, the transformer usually has three sets of windings (the coaxially wound high-voltage winding and low-voltage winding are one group). In other words, a transformer has three of the above-mentioned semi-enclosed spaces.

[0020] Preferably, an L tube, an M tube, and an R tube are respectively installed on the three outer plates from left to right, the protruding end of the M tube is connected to the connecting seat in the middle and upper part, the protruding ends of the L tube and the R tube are both connected to the M tube, and the angles between the L tube and the R tube and the M tube are different and are all acute angles;

[0021] In the above scheme, L tube, M tube and R tube are used to connect the three semi-enclosed spaces respectively, so as to collect the high-temperature oil and impurities inside the three semi-enclosed spaces into one place, filter them to remove impurities, and allow the high-temperature oil to directly enter the cooling device for efficient cooling; the angles between the L tube, R tube and M tube are different to avoid the oil discharged from the L tube and R tube from colliding, resulting in reduced oil circulation efficiency. The angles between the L tube, R tube and M tube are all acute angles to improve the connection strength of the L tube, M tube and R tube, so as to improve the stability of the transformer operation.

[0022] Preferably, the maximum height of the L tube, the M tube, and the R tube is less than the liquid level of the oil in the oil tank;

[0023] Through the above scheme, according to the principle of communicating vessels, the oil in the L-tube, M-tube and R-tube is pressurized and discharged to the through-tube, so as to accelerate the natural oil circulation, thereby quickly removing impurities and improving the cooling efficiency of the transformer. The L-tube, M-tube and R-tube are filled with oil, thereby reducing the high-voltage discharge phenomenon induced by bubbles.

[0024] Preferably, the through pipe connected to the M tube includes a pipe body and a pipe head, one end of the pipe body is connected to the connecting seat, and the pipe head is connected to the other end of the pipe body. A horizontal plate is installed inside the pipe body, and the filter is installed on the pipe head, and the filter abuts against the horizontal plate.

[0025] In the above solution, the filter is a consumable part installed on the pipe head and can be quickly replaced by disassembling and assembling the pipe head; the structure formed by the connection between the filter and the cross plate allows the oil to enter the bottom of the cross plate after filtering at the front end, and enter each fin in turn from front to back, so that the oil that is still at a higher temperature after filtering is completed first enters the front fins to receive more superior cooling effect.

[0026] Preferably, the tube body includes an outlet and an inlet, the outlet and the inlet are respectively located above and below the horizontal plate, and the outlet and the inlet are both configured as tapered hole structures with the smaller diameter facing outwards, pistons are arranged inside the outlet and the inlet, and a push rod is arranged on the tube head, and the two push rods are coaxial with the outlet and the inlet respectively;

[0027] Through the above solution, when the tube head is installed on the tube body, the push rod pushes the piston, and the oil inside the tube body circulates normally to achieve natural oil circulation; when the tube head is removed from the tube body, the push rod will pull the two pistons into the outlet and inlet respectively, and the pistons will press the outlet and inlet tightly under the oil pressure, thereby preventing the tube body from leaking when the tube head is removed.

[0028] During the operation of the transformer, the oil is discharged from the upper connection seat to the through-tube, cooled by the fins, and then discharged into the oil tank from the lower connection seat through the through-tube. The oil has a certain speed and momentum when it is discharged. If it hits the bottom plate, it will cause the transformer to vibrate, which is detrimental to the stability of the operation.

[0029] Preferably, a vibration damping hole is opened on the bottom plate, the vibration damping hole is coaxial with the connecting seat below, the inner hole of the connecting seat below has a taper, and the small diameter end of the inner hole of the connecting seat below is on the inner side of the oil tank;

[0030] In the above scheme, the inner hole of the lower connecting seat is made into a tapered hole, and a vibration-damping hole coaxial with the tapered hole is opened on the bottom plate, so that the oil discharged from the lower connecting seat directly enters the vibration-damping hole, thereby avoiding collision with the bottom plate and avoiding the generation of corresponding vibrations. The setting of the vibration-damping hole reduces the weight of the bottom plate, making the bottom plate easier to install and also providing convenience for the transportation of the equipment.

[0031] A support plate needs to be arranged between the support frame and the body to ensure that there is enough gap between the two for the oil to pass through. However, if the height of the support plate is too large, it will affect the stability of the body.

[0032] Preferably, the support frame is provided with support plates, the support plates are installed in pairs, each of the inner plate and the outer plate is installed on two pairs of support plates, and the support frame is provided with a through slot, the through slot is located above the support frame, and the through slot is located between each pair of support plates;

[0033] In the above solution, a through groove is opened between each pair of support plates. On the one hand, it allows the oil to enter the device body more smoothly, thereby playing a cooling and insulating role; on the other hand, it reduces the weight of the support frame and facilitates transportation and installation.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The present invention uses a semi-enclosed space formed by connecting the inner and outer plates to collect impurities generated by high-temperature oxidation of the oil near the winding. By utilizing the principle of hot and cold convection, the high-temperature oil in the semi-enclosed space drives the impurities to float up for circulation. This allows the high-temperature oil to dissipate heat while filtering out a large amount of accumulated impurities, thereby preventing the continued negative impact of residual impurities on the transformer.

[0036] 2. The present invention arranges oil paper with ridges on both sides between the high-voltage winding and the low-voltage winding to enhance the heat dissipation capacity of the transformer. The shape of the outer plate is designed so that the oil under the oil tank can smoothly enter the gap formed by the ridges and the winding, thereby further accelerating the circulation and enhancing heat dissipation. Moreover, the speed at which the oil enters is gradually increased by the diameter change of the outer plate, thereby carrying impurities through the gap, so that a large amount of impurities can be effectively removed.

[0037] 3. The present invention provides a transverse plate inside the tube body and a filter inside the tube head. When the tube body and the tube head are combined, the oil circulates, and the filtered oil enters the fins from front to back, so that the oil with high temperature falls on the front side to achieve better heat dissipation, thereby improving the overall heat dissipation effect of the transformer. When the tube body and the tube head are not combined, the inside of the tube body is blocked by the piston, thereby avoiding leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall isometric structure of the present invention;

[0039] Figure 2 It is a schematic diagram of the overall internal cross-sectional structure of the present invention;

[0040] Figure 3 For the present invention Figure 2 A magnified schematic diagram of part A;

[0041] Figure 4 This is a schematic diagram of the oil paper structure of the present invention;

[0042] Figure 5 A schematic diagram of a half-section view of the device of the present invention;

[0043] Figure 6 Schematic diagram of the structure of the L tube, M tube and R tube of the present invention;

[0044] Figure 7 For the present invention Figure 2 A magnified schematic diagram of part B;

[0045] Figure 8 It is a schematic diagram of the tube head separation state of the present invention.

[0046] In the figure: 1. Oil pillow; 2. Oil tank; 21. Connecting seat; 3. Cooler; 31. Through pipe; 311. Pipe body; 3111. Cross plate; 3112. Outlet; 3113. Inlet; 3114. Piston; 312. Pipe head; 3121. Push rod; 32. Fin; 4. Outlet terminal; 5. Body; 51. Iron core; 52. Inner plate; 53. Low-voltage winding; 54. Oil paper; 541. Ridge; 55. High-voltage winding; 56. Outer plate; 6. Support frame; 61. Through slot; 7. Bottom plate; 71. Vibration damping hole; 8. Filter; 9. L-tube; 10. M-tube; 11. R-tube. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See also Figures 1 to 8 The present invention provides an oil-immersed power transformer, and the technical solution is as follows:

[0049] An oil-immersed power transformer includes an oil pillow 1, an oil tank 2, a cooler 3, an outlet terminal 4, a body 5, a support frame 6, and a bottom plate 7. The oil tank 2 is divided into a box body and a box cover. In order to avoid high-voltage discharge caused by residual bubbles in the oil, before flushing oil into the oil tank 2, the box cover is first covered on the box body, and a sealing ring is installed between the two to achieve a sealed connection. Then, a vacuum operation is performed to reduce the mixed content of gas in the oil; the oil pillow 1 is installed on the box body, and the oil pillow 1 acts as a buffer tank 2. When the volume of the oil in the oil tank 2 changes (such as thermal expansion and contraction), the oil pillow 1 is flushed to the oil tank 2. The oil is replenished or extracted from the oil tank to maintain the stability of the internal pressure of the oil tank 2. A gas relay is arranged on the pipe connecting the oil pillow 1 and the oil tank 2. Accidents are usually accompanied by high temperatures inside the oil tank 2. The oil will produce gas under high temperature. By monitoring the gas content, the gas relay can judge the severity of the accident and automatically perform corresponding actions. A breathing valve is also arranged under the oil pillow 1 to discharge the gas inside the oil tank 2 while preventing external gas and moisture from entering. The outlet terminal 4 is wrapped with a porcelain bushing for phase-to-phase insulation and relative insulation. The bottom plate 7 is The installation platform of the device body 5; in order to facilitate the installation of the inner plate 52 and the outer plate 56, the iron core 51 is divided into two parts, the lower part of which is a "mountain" shaped structure, and the upper part is a "one" shaped structure. The support frame 6 is used to fix the iron core 51 of the "mountain" shaped structure. After the installation of the inner plate 52 and the outer plate 56 is completed, the "one" shaped structure iron core 51 is placed above the "mountain" shaped structure iron core 51 and fixed with a strap; it also includes a filter 8, a connecting seat 21 is arranged in front of the oil tank 2, and the connecting seat 21 is paired up and down. The cooler 3 includes a through pipe 31 and a fin 32. The through pipe 31 is installed on the connecting seat 2 1, multiple fins 32 are arranged between each pair of through-tubes 31, the body 5 includes an iron core 51, a high-voltage winding 55, a low-voltage winding 53, an oil-paper 54, an inner plate 52 and an outer plate 56. The iron core 51 is located above the inner bottom of the oil tank 2, and the low-voltage winding 53 and the high-voltage winding 55 are wound on the iron core 51 from the inside to the outside. The oil-paper 54 is located between the low-voltage winding 53 and the high-voltage winding 55. The inner plate 52 is located inside the low-voltage winding 53, and the outer plate 56 is located outside the high-voltage winding 55. The interior of the outer plate 56 is connected to the connecting seat 21 above. The filter 8 is installed on the protruding side of the through-tube 31;

[0050] The inner plate 52 and the outer plate 56 are snapped together to form an enclosure for the upper side and peripheral surface of the high-voltage winding 55 and the low-voltage winding 53. The filter 8 absorbs impurities in the high-temperature oil discharged from the inside of the inner plate 52 and the outer plate 56 to the through pipe 31, and the purified high-temperature oil is cooled by the fins 32 and then guided back to the bottom of the oil tank 2 through the through pipe 31 below.

[0051] As an embodiment of the present invention, refer to Figure 3 The upper end of the outer plate 56 is bent inward, and the upper part of the inner plate 52 is clamped with the bent part of the outer plate 56, thereby forming a semi-enclosed space with an opening downward. The high-voltage winding 55 and the low-voltage winding 53 are both located inside this space. The oil in the semi-enclosed space is heated and floats up and is directly discharged to the cooler 3. During the floating process, it does not directly contact the oil outside the outer plate 56, thereby directly taking a large amount of heat out of the oil tank 2; the outer plate 56 and the inner plate 52 are both made of alumina (aluminum oxide) material, because alumina material has good insulation properties and excellent thermal conductivity. Although high-temperature oil directly enters the cooler 3, it can achieve a better cooling effect, but the high temperature inside the semi-enclosed space will accelerate the oxidation of the oil, thereby increasing the rate of impurity generation. Therefore, the heat exchange between the semi-enclosed internal space and the external space is accelerated by the alumina material with higher thermal conductivity; the outer plate 56 and the inner plate 52 can first be shaped by a sheet metal process, then bent into a ring shape, and welded, and insulating paint needs to be applied after welding.

[0052] As an embodiment of the present invention, refer to Figure 3 and Figure 4 The two sides of the oil paper 54 are provided with ridges 541, and the ridges 541 are arranged at equal intervals; the oil paper 54 is made of insulating material, and the cross-section of the ridges 541 is set to a semicircular shape to prevent the generation of corners, thereby avoiding scratching the high-voltage winding 55 and the low-voltage winding 53. The specific production method of the oil paper 54 can refer to corrugated paper.

[0053] As an embodiment of the present invention, refer to Figure 2 、 Figure 3 and Figure 5 The inner wall of the upper part of the outer plate 56 is in contact with the high-voltage winding 55, and the inner diameter of the lower part of the outer plate 56 gradually increases from top to bottom. During operation, after the high-temperature oil in the semi-enclosed space formed by the outer plate 56 and the inner plate 52 floats up, the oil below the oil tank 2 flows into the semi-enclosed space to replenish it. During the flow, the flow radius of the oil gradually decreases, so the flow rate of the oil gradually increases, thereby carrying impurities near the winding, passing through the gap between the ridge 541 and the winding, entering the upper part of the semi-enclosed space, and continuing to float up into the tube body 311 for filtration and cooling.

[0054] As an embodiment of the present invention, refer to Figure 1 and Figure 6, the three outer plates 56 from left to right are respectively installed with an L tube 9, an M tube 10 and an R tube 11. The protruding end of the M tube 10 is connected to the connecting seat 21 in the middle and upper part. The protruding ends of the L tube 9 and the R tube 11 are both connected to the M tube 10. The angles between the L tube 9 and the R tube 11 and the M tube 10 are different and are all acute angles; the maximum heights of the L tube 9, the M tube 10 and the R tube 11 are less than the liquid level of the oil in the oil tank 2; the L tube 9, the M tube 10 and the R tube 11 are all right-angle pipes, and the right angles can also be changed to blunt angles according to the actual space of the transformer. Angles are formed to further reduce the corner losses of oil flowing in the pipeline, thereby accelerating the speed of natural circulation. The internal temperature of an oil-immersed power transformer usually does not exceed 105°C. The L tube 9, M tube 10, and R tube 11 can be made of thermosetting plastic. During operation, the high-temperature oil inside the outer plates 56 on both sides is respectively collected into the M tube 10 through the L tube 9 and R tube 11, and is uniformly discharged from the M tube 10 into the tube body 311, thereby entering the filter 8 to remove impurities. The filtered oil then falls into the fins 32 for cooling.

[0055] As an embodiment of the present invention, refer to Figure 2 and Figure 7 The through pipe 31 connected to the M tube 10 includes a tube body 311 and a tube head 312. One end of the tube body 311 is connected to the connecting seat 21, and the tube head 312 is connected to the other end of the tube body 311. A horizontal plate 3111 is installed inside the tube body 311, and the filter 8 is installed on the tube head 312. The filter 8 abuts against the horizontal plate 3111; the longitudinal section of the horizontal plate 3111 is "L" shaped, and grooves are provided on both sides of the tube body 311 so that the horizontal plate 3111 can slide into the tube from the rear end of the tube body 311. The body 311 is formed by the short side of the "L" of the horizontal plate 3111, and the lower space of the rear port of the tube body 311 is blocked, so that the high-temperature oil flowing in from the M tube 10 passes from the top of the horizontal plate 3111, is filtered by the filter 8, and then is conducted to the bottom of the horizontal plate 3111, and falls into the fins 32 from front to back to receive cooling with gradually decreasing intensity; the filter 8 can be detachably installed (plugged or bolted) inside the tube head 312, and the filter 8 should be replaced regularly according to the working intensity of the transformer.

[0056] As an embodiment of the present invention, refer to Figure 7 and Figure 8The tube body 311 includes an outlet 3112 and an inlet 3113, which are respectively located above and below the horizontal plate 3111, and the outlet 3112 and the inlet 3113 are both configured as a tapered hole structure with a small diameter facing outward, and pistons 3114 are arranged inside the outlet 3112 and the inlet 3113. A push rod 3121 is arranged on the tube head 312, and the two push rods 3121 are coaxial with the outlet 3112 and the inlet 3113 respectively; the push rod 3121 pushes the piston 3114, and the oil inside the tube body 311 circulates normally to perform natural oil circulation; when the tube head 312 is removed from the tube body 311, the push rod 3121 will pull the two pistons 3114 into the outlet 3112 and the inlet 3113 respectively, and the pistons 3114 are 114 will press the outlet 3112 and the inlet 3113 tightly under the oil pressure, thereby preventing the tube body 311 from leaking when the tube head 312 is removed. A groove is provided on the front side of the piston 3114 for the push rod 3121 to be inserted. To facilitate the insertion of the push rod 3121 into the groove on the front side of the piston 3114, the rear end of the push rod 3121 can be made into a frustum, with the small diameter end at the rear, and the shape of the groove of the piston 3114 is matched with the frustum structure of the push rod 3121; in addition, the filtered high-temperature oil will flow into the space under the cross plate 3111. At this time, the flow of oil will push the piston 3114 to disengage from the push rod 3121. To avoid this phenomenon, a block is provided under the cross plate 3111 (on the rear side of the piston 3114) to position the piston 3114.

[0057] As an embodiment of the present invention, refer to Figure 2 A damping hole 71 is provided on the bottom plate 7, which is coaxial with the connecting seat 21 below. The inner hole of the connecting seat 21 below is tapered, and the small diameter end of the inner hole of the connecting seat 21 below is on the inner side of the oil tank 2. The damping hole 71 is opened as a through hole to minimize weight and avoid the impact of oil on the bottom plate 7.

[0058] As an embodiment of the present invention, refer to Figure 6 , support plates are arranged on the support frame 6, and the support plates are installed in pairs. Each inner plate 52 and outer plate 56 are installed on two pairs of support plates. A through slot 61 is opened on the support frame 6. The through slot 61 is located above the support frame 6, and the through slot 61 is located between each pair of support plates. The support frame 6 uses channel steel, and the support plates are welded to the support frame 6. The inner plate 52 and the outer plate 56 are fixed to the support plates by bolts.

[0059] Working principle: There is copper loss in the high-voltage winding 55 and the low-voltage winding 53 in the power transformer during operation, which will release heat, causing the nearby oil to be heated and oxidized to generate impurities. The accumulation of impurities will degrade the performance of the oil, so the impurities need to be removed in time. In the existing natural oil circulation cooling transformer, the oil circulation speed is low, and correspondingly, the impurity removal speed is also low. Impurities that cannot be removed in time will have a lasting impact on the performance of the transformer. Therefore, the present invention intends to remove impurities in time without changing the circulation speed. First, impurities are mainly generated near the winding. In order to prevent them from spreading to the surrounding areas of the oil tank 2, which increases the difficulty of cleaning, the impurities are first gathered in one place, that is, inside the semi-enclosed space formed by the outer plate 56 and the inner plate 52 in the present invention; secondly, to clean the gathered impurities, the present invention sets a filter 8 before the oil enters the fin 32, and through the installation method of the filter 8, the oil can be cooled with different intensities according to its own temperature gradient;

[0060] Specifically, in order to provide a space for impurities to accumulate, the upper end of the outer plate 56 is bent inward, and the upper portion of the inner plate 52 is clamped to the bent portion of the outer plate 56, thereby forming a semi-enclosed space with an opening facing downward. The high-voltage winding 55 and the low-voltage winding 53 are both located inside this space. Impurities generated by oxidation of the oil in the semi-enclosed space will float up along with the oil and enter the cooler 3.

[0061] To prevent impurities from entering and remaining in the semi-enclosed space, the inner wall of the upper portion of the outer plate 56 is fitted against the high-voltage winding 55, and the inner diameter of the lower portion of the outer plate 56 is gradually increased from top to bottom. Ridges 541 are provided on both sides of the oil paper 54. By varying the inner diameter of the lower portion of the outer plate 56, the speed of the oil entering the semi-enclosed space is gradually increased, allowing the impurities to pass through the gaps between the ridges 541 of the oil paper 54 and the low-voltage winding 53 and the high-voltage winding 55, and enter the upper portion of the semi-enclosed space. The arrangement of the upper portion of the outer plate 56 allows the high-voltage winding 55 to fit against the inner wall, which, on the one hand, makes the installation of the outer plate 56 more stable, and on the other hand, blocks the path for impurities to flow back, concentrating the impurities inside the outer plate 56.

[0062] In order to gather impurities in the three closed spaces in one place so as to be removed at the same place, thereby facilitating subsequent maintenance, an L tube 9, an M tube 10, and an R tube 11 are respectively installed on the three outer plates 56. The protruding end of the M tube 10 is connected to the connecting seat 21 in the middle and upper part, and the protruding ends of the L tube 9 and the R tube 11 are both connected to the M tube 10. The high-temperature oil and impurities in the three semi-enclosed spaces are collected in the M tube 10 and discharged to the through pipe 31 connected to the M tube 10. The angles between the L tube 9 and the R tube 11 and the M tube 10 are different and are all acute angles. On the one hand, this avoids the oil discharged from the L tube 9 and the R tube 11 from colliding, thereby avoiding the reduction of the oil circulation efficiency; on the other hand, it improves the connection strength of the L tube 9, the M tube 10, and the R tube 11, thereby improving the stability of the transformer operation.

[0063] In order to allow the oil to be cooled to different intensities according to its own temperature gradient, a transverse plate 3111 is installed inside the tube body 311, and a filter 8 is installed inside the tube head 312. After the transverse plate 3111 abuts against the filter 8, the oil is filtered at the front end of the tube body 311 and then enters the bottom of the transverse plate 3111. Then, it enters each fin 32 from the front to the back. In this way, the oil that has been filtered first and still has a higher temperature enters the front fin 32 to receive a more effective cooling effect.

[0064] To facilitate the replacement of the filter 8, an outlet 3112 and an inlet 3113 are provided at the front end of the tube body 311, and pistons 3114 are arranged at the outlet 3112 and the inlet 3113. When the tube head 312 is installed on the tube body 311, the push rod 3121 pushes the piston 3114, and the oil inside the tube body 311 circulates normally to perform natural oil circulation. When the tube head 312 is removed from the tube body 311, the push rod 3121 will pull the two pistons 3114 into the outlet 3112 and the inlet 3113 respectively, and the pistons 3114 will press the outlet 3112 and the inlet 3113 tightly under the oil pressure, thereby preventing the tube body 311 from leaking when the tube head 312 is removed.

[0065] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An oil-immersed power transformer, comprising an oil pillow (1), an oil tank (2), a cooler (3), an outlet terminal (4), a transformer body (5), a support frame (6) and a base plate (7), characterized in that: The invention also includes a filter (8). A connecting seat (21) is arranged in front of the oil tank (2). The connecting seats (21) are paired up and down. The cooler (3) includes a through pipe (31) and fins (32). The through pipe (31) is installed on the connecting seat (21). A plurality of fins (32) are arranged between each pair of through pipes (31). The body (5) includes an iron core (51), an inner plate (52), a low-voltage winding (53), oil paper (54), a high-voltage winding (55) and an outer plate (56). The core (51) is located above the inner bottom of the oil tank (2); the low-voltage winding (53) and the high-voltage winding (55) are wound on the iron core (51) in sequence from the inside to the outside; the oil paper (54) is located between the low-voltage winding (53) and the high-voltage winding (55); the inner plate (52) is located inside the low-voltage winding (53); the outer plate (56) is located outside the high-voltage winding (55); and the interior of the outer plate (56) is connected to the upper connecting seat (21); and the filter (8) is installed on the protruding side of the through pipe (31); The inner plate (52) and the outer plate (56) are connected to form an enclosure around the upper side and the peripheral surface of the high-voltage winding (55) and the low-voltage winding (53). The filter (8) absorbs impurities in the high-temperature oil discharged from the inside of the inner plate (52) and the outer plate (56) to the through pipe (31). The purified high-temperature oil is cooled by the fins (32) and then guided back to the bottom of the oil tank (2) through the through pipe (31) below.

2. The oil-immersed power transformer according to claim 1, characterized in that: Both side surfaces of the oil paper (54) are provided with ridges (541), and the ridges (541) are arranged at equal intervals.

3. The oil-immersed power transformer according to claim 1, characterized in that: The upper end of the outer plate (56) is bent inward, and the upper portion of the inner plate (52) is clamped to the bent portion of the outer plate (56).

4. The oil-immersed power transformer according to claim 3, characterized in that: The inner wall of the upper portion of the outer plate (56) is in contact with the high-voltage winding (55), and the inner diameter of the lower portion of the outer plate (56) gradually increases from top to bottom.

5. The oil-immersed power transformer according to claim 1, characterized in that: The three outer plates (56) from left to right are respectively mounted with an L tube (9), an M tube (10) and an R tube (11), the extended end of the M tube (10) is connected to the upper middle connection seat (21), the extended ends of the L tube (9) and the R tube (11) are both connected to the M tube (10), and the angles between the L tube (9) and the R tube (11) and the M tube (10) are different and are all acute angles.

6. The oil-immersed power transformer according to claim 5, characterized in that: The maximum heights of the L tube (9), the M tube (10) and the R tube (11) are less than the liquid level of the oil in the oil tank (2).

7. The oil-immersed power transformer according to claim 5, characterized in that: The through pipe (31) connected to the M pipe (10) comprises a pipe body (311) and a pipe head (312); one end of the pipe body (311) is connected to the connecting seat (21); the pipe head (312) is connected to the other end of the pipe body (311); a transverse plate (3111) is installed inside the pipe body (311); the filter (8) is installed on the pipe head (312); and the filter (8) abuts against the transverse plate (3111).

8. The oil-immersed power transformer according to claim 7, characterized in that: The tube body (311) includes an outlet (3112) and an inlet (3113), the outlet (3112) and the inlet (3113) being located above and below the transverse plate (3111), respectively, and the outlet (3112) and the inlet (3113) being both configured as tapered hole structures with the smaller diameter facing outward, pistons (3114) being arranged inside the outlet (3112) and the inlet (3113), and a push rod (3121) being arranged on the tube head (312), and the two push rods (3121) being coaxial with the outlet (3112) and the inlet (3113), respectively.

9. The oil-immersed power transformer according to claim 1, characterized in that: A vibration damping hole (71) is provided on the bottom plate (7), and the vibration damping hole (71) is coaxial with the lower connecting seat (21). The inner hole of the lower connecting seat (21) has a taper, and the small diameter end of the inner hole of the lower connecting seat (21) is located inside the oil tank (2).

10. The oil-immersed power transformer according to claim 1, characterized in that: The support frame (6) is provided with support plates, which are installed in pairs. Each inner plate (52) and outer plate (56) is installed on two pairs of support plates. A through slot (61) is provided on the support frame (6). The through slot (61) is located above the support frame (6), and the through slot (61) is located between each pair of support plates.

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