Natural ester insulating oil transformer

Abstract

A natural ester insulating oil transformer, which includes an oil tank storing natural ester insulating oil and a plurality of coil pancakes arranged in the oil tank and immersed in the natural ester insulating oil; in the same coil pancake, a winding oil duct forming plate for forming a winding oil duct is arranged between adjacent two coil layers; between two adjacent coil pancakes stacked coaxially, a plurality of oil duct hub forming plates for forming an inter-pancake oil duct are evenly distributed; each oil duct hub forming plate includes at least one radially long hole for butting against the winding oil duct, and the oil duct hub forming plate is an isosceles trapezoid structure, its short bottom side corresponds to the inner diameter end of the coil pancake, its long bottom side corresponds to the outer diameter end of the coil pancake, and the radially long hole is arranged along the radial direction of the coil pancake and communicated with the winding oil duct, reducing the blocking effect on the natural ester insulating oil and being beneficial to improving the heat exchange efficiency.

Description

Technical Field

[0001] The present invention relates to the field of power transformers, and particularly to a natural ester insulating oil transformer with an explosion-proof oil tank. Background Art

[0002] In existing oil-immersed transformers, mineral insulating oil (generally obtained from petroleum refining) is filled inside, which mainly serves two purposes: one is as an insulating material, which can insulate high-voltage conductors at different positions and different phase sequences. Based on the good insulation effect of mineral insulating oil, the insulation distance can be reduced, and the size of the transformer can be decreased; the other is based on its good fluidity. According to the siphon effect, due to the temperature difference at different positions in the oil tank of the oil-immersed transformer, it promotes the free flow of the insulating oil. The oil at the high-temperature position automatically flows to positions such as radiators and the tank wall, playing a heat dissipation effect. However, the flash point of mineral insulating oil is generally around 150 - 170 degrees Celsius. When a transformer encounters a fault and catches fire, it is prone to explosion. Therefore, existing oil-immersed transformers have gradually started to use natural ester insulating oil to fill the oil tank. Natural ester insulating oil has a high combustion resistance characteristic. For example, its flash point is about 330 °C, and its ignition point is about 350 °C. Therefore, it can effectively prevent the transformer from exploding and greatly improve the safety of the oil-immersed transformer. However, due to the relatively high viscosity of natural ester insulating oil, and the oil duct and other structures of the coils in existing transformers are designed according to mineral insulating oil, there are many new problems brought about by replacing with natural ester insulating oil. For example, due to its lack of axial winding oil ducts, there is no connection between the axial and radial directions of the oil ducts, and the inner end of the radial oil duct is narrow and the outer end is wide and other defects, making it impossible for natural ester insulating oil to flow freely and difficult to penetrate deep into the coil, thus seriously affecting the heat dissipation speed of the transformer and easily causing damage, faults, and a decrease in the service life of the transformer due to high temperature.

[0003] In addition, since the viscosity of natural ester insulating oil is 3 - 4 times that of ordinary insulating oil, it is not easy to diffuse the Joule heat inside the coil to the outside of the transformer, and at the same time, it is easy to increase the pressure inside the transformer. And due to the unreasonable structure of the oil tank of existing transformers, their pressure resistance is low. Usually, the negative pressure only reaches 133 kP (when evacuating), and the positive pressure only reaches 80 - 100 kP (when pressurizing), which cannot meet the safety operation requirements of natural ester insulating oil transformers. Especially for transformers without an automatic pressure relief structure, their safety level will be reduced. However, the improvement of the oil tank and the pressure relief structure will inevitably involve the noise reduction structure of the transformer, or rather, it is necessary to improve the anti-noise pollution structure accordingly. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a natural ester insulating oil transformer with high safety and good heat dissipation.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A natural ester insulating oil transformer, which comprises an oil tank storing natural ester insulating oil and a plurality of coil cakes arranged in the oil tank and immersed in the natural ester insulating oil; in the same coil cake, a winding oil duct forming plate for forming a winding oil duct is arranged between adjacent two coil layers; between two adjacent coil cakes stacked coaxially, a plurality of multi-functional oil duct hub forming plates for forming an inter-cake oil duct are evenly distributed; each oil duct hub forming plate comprises at least one radial long hole for butting against the winding oil duct, and the oil duct hub forming plate is of an isosceles trapezoid structure, its short bottom edge corresponds to the inner diameter end of the coil cake, its long bottom edge corresponds to the outer diameter end of the coil cake, and the radial long hole is arranged along the radial direction of the coil cake and communicated with the winding oil duct.

[0007] Preferably, the winding oil duct forming plate comprises a substrate and a plurality of columns of support protrusion arrays arranged on the substrate, each support protrusion array comprises a plurality of support protrusions evenly distributed at equal intervals, and each support protrusion is a conical boss, and its large diameter end is connected with the substrate; the winding oil duct forming plate is arranged between adjacent two coil layers, the substrate is attached to one of the coil layers, the small diameter end of the support protrusion abuts against the other coil layer, and a plurality of support protrusions are evenly distributed between the two coil layers to form a winding oil duct.

[0008] Preferably, the thickness of the substrate is 0.5-1.0 mm, and the height of the support protrusion is 5-15 mm.

[0009] Preferably, the coil cake is wound by flat copper wires, and the winding oil duct formed by the winding oil duct forming plate between adjacent two coil layers is an inter-turn oil duct between single-turn copper wires, which comprises a substrate and a plurality of columns of support protrusions, and the width of the substrate is the same as the width of the flat copper wire.

[0010] Preferably, the oil duct hub forming plate further comprises an outer limiting groove and an inner limiting groove respectively arranged on the long bottom edge and the short bottom edge; an inner coil support bar is arranged inside the coil cake, and an outer coil support bar is arranged outside the coil cake, and the inner limiting groove is in limiting cooperation with the inner coil support bar, and the outer limiting groove is in limiting cooperation with the outer coil support bar.

[0011] Preferably, the oil tank comprises an inner box body and an outer box body, the inner box body comprises a top wall, a bottom wall and side walls arranged between the top wall and the bottom wall, the outer box body comprises a plurality of U-shaped reinforcing irons which are spaced apart and welded on the side walls of the inner box body, each reinforcing iron extends from the top wall of the inner box body to the bottom wall of the inner box body, and a reinforcing iron plate respectively welded to the two reinforcing irons is arranged between two adjacent reinforcing irons.

[0012] Preferably, flange assemblies are provided at the top and bottom of each of the reinforcing irons; each reinforcing iron plate and the two adjacent reinforcing irons enclose a cavity, and flange assemblies are provided at the top and bottom of the cavity; each flange assembly includes a flange and a cover plate corresponding to and cooperating with the flange; sand or asbestos material is filled in both the reinforcing iron and the cavity.

[0013] Preferably, the fuel tank further includes two pressure relief structures, which are respectively arranged at both ends of the upper part of the fuel tank. One end of each pressure relief structure communicates with the inner tank body of the fuel tank, and the other end communicates with the fault oil sump.

[0014] Preferably, the fuel tank further includes a quick-acting oil pressure relay arranged on its upper part and communicating with the inner tank body of the fuel tank.

[0015] Preferably, the circumferential oil ducts are distributed on the large curved surface formed by the axial and circumferential directions between adjacent two coil layers, and the circumferential oil ducts not only penetrate axially but also penetrate circumferentially on the large curved surface.

[0016] Preferably, each inter-pancake oil duct extends along the radial end face to the inner and outer sides of the coil pancake; inner axial oil ducts and outer axial oil ducts are respectively arranged on the inner and outer sides of each coil pancake, and each inter-pancake oil duct communicates with the circumferential oil duct, the inner axial oil duct and the outer axial oil duct respectively.

[0017] Preferably, the circumferential oil duct is formed by a plurality of support protrusions arranged on a circumferential oil duct forming plate; the circumferential oil duct forming plate includes a base plate and a plurality of support protrusions formed thereon. The spaced gaps between the support protrusions form the circumferential oil duct, and the spaced gaps are distributed along the radial and axial directions on the entire base plate and penetrate through the base plate completely.

[0018] Preferably, the inner axial oil duct and the outer axial oil duct are respectively formed by a plurality of inner support bars arranged axially, a plurality of outer support bars and a plurality of oil duct hub forming plates arranged between adjacent two coil pancakes; each oil duct hub forming plate includes an inner bottom edge corresponding to and matching the inner side of the coil pancake and an outer bottom edge corresponding to and matching the outer side of the coil pancake; an outer limiting groove is provided on the outer bottom edge for fixed cooperation with the outer support bar; an inner limiting groove is provided on the inner bottom edge for fixed cooperation with the inner support bar; through the fixed cooperation and assembly of the oil duct hub forming plate with the inner support bar and the outer support bar, the axially stacked coil pancakes are positioned axially and radially, and in addition, an inner gap used as the inner axial oil duct is formed between adjacent two inner support bars, and an outer gap used as the outer axial oil duct is formed between adjacent two outer support bars.

[0019] Preferably, a plurality of oil duct hub forming plates are arranged between two adjacent coil pancakes. The oil duct hub forming plates together form an inter-pancake oil duct, an inner axial oil duct, an outer axial oil duct, and an axial docking oil duct, and each oil duct hub forming plate respectively forms a hub for the interconnection of the circumferential oil duct, the inter-pancake oil duct, the inner axial oil duct, the outer axial oil duct, and the axial docking oil duct.

[0020] In the natural ester insulating oil transformer of the present invention, the oil duct hub forming plate has an isosceles trapezoid structure, such that the widths of the inner end and the outer end of the radial oil duct formed between two adjacent oil duct hub forming plates are nearly the same, so that the natural ester insulating oil can penetrate deep into the coil pancake, which is beneficial to improving the heat exchange efficiency. Moreover, the oil duct hub forming plate includes a radial long hole, and the radial long hole is communicated with the axial oil duct, thus significantly reducing the blocking effect of the oil duct hub forming plate on the axially flowing natural ester insulating oil, enabling the natural ester insulating oil to freely flow in the oil duct network formed by the axial oil duct and the radial oil duct, further improving the heat exchange effect of the transformer; and the natural ester insulating oil has a higher flash point and ignition point compared with the mineral insulating oil, which is also beneficial to improving the safety of the transformer.

[0021] In addition, a circumferential oil duct is arranged between adjacent coil layers of the coil pancake. It is distributed on the entire large curved surface formed by the axial and circumferential directions between adjacent coil layers and is fully penetrated on this large curved surface, not only axially penetrated but also circumferentially penetrated, so that the insulating oil in the circumferential oil duct can convect unobstructedly in both the radial and circumferential directions, having the remarkable effects of reducing the core temperature inside the coil, balancing the internal temperature difference of the transformer, and accelerating the heat dissipation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic plan view of the overall external structure of an embodiment of the natural ester insulating oil transformer of the present invention;

[0023] Figure 2 is a schematic partial structure view of the coil pancake 6 of the present invention, showing two adjacent coil layers (61, 62) therein, and the structures of the circumferential oil duct 7a and the circumferential oil duct forming plate 7 arranged between them;

[0024] Figure 3 is a schematic overall structure view of the circumferential oil duct forming plate 7 component of the present invention, showing the distribution structure of the circumferential oil duct 7a and the structure of a multi-column support protrusion array composed of a substrate 70 and a plurality of support protrusions 71 arranged thereon;

[0025] Figure 4 is a schematic partial structure view of the circumferential oil duct forming plate 7 of the present invention, which is Figure 3 an upward partial enlarged view, showing the structure of the support protrusion 71;

[0026] Figure 5 It is a schematic assembly structure diagram of the coil cake 6 and the oil duct hub forming plate 8 of the present invention. The figure shows the oil duct structures of the inter-cake oil duct 8a, the inner axial oil duct 6a, and the outer axial oil duct 6b formed after assembly;

[0027] Figure 6 It is a schematic structure diagram of an embodiment of the oil duct hub forming plate 8 part of the present invention. The figure shows its isosceles trapezoid structure composed of a long bottom side and a short bottom side, as well as the structures of the outer limiting groove 82, the inner limiting groove 83, and the radially long hole 81 (i.e., the axial docking oil duct) provided thereon;

[0028] Figure 7 It is a three-dimensional structure schematic diagram of the natural ester insulating oil transformer of the present invention. Specific Embodiments

[0029] The following combines the Figure 1-7 embodiments given to further illustrate the specific embodiments of the natural ester insulating oil transformer of the present invention. The natural ester insulating oil transformer of the present invention is not limited to the descriptions of the following embodiments.

[0030] Figures 1 to 7 In the embodiments given, the insulating oil uses natural ester insulating oil, so it is a natural ester insulating oil transformer, which includes an oil tank storing natural ester insulating oil and a plurality of coil cakes 6 arranged in the oil tank and immersed in the natural ester insulating oil;

[0031] In the same coil cake 6, a winding oil duct forming plate 7 for forming a winding oil duct 7a is provided between adjacent two coil layers (i.e., the outer coil layer 61 and the inner coil layer 62). Herein, the winding direction refers to the winding direction of the coil wire (the same hereinafter), which is different from the usually mentioned radial or axial direction. Each phase winding of the transformer is formed by coaxially stacking a plurality of coil cakes 6; a plurality of oil duct hub forming plates 8 for forming the inter-cake oil duct 8a are evenly distributed between two adjacent coaxially stacked coil cakes 6. It should be noted that the difference between the oil duct hub forming plate 8 of the present invention and the existing spacer is that: it is not only used for the separation and support between the coil cakes 6, but also used for the axial and radial positioning of the coil cakes 6 and to form a radial oil duct; in particular, it is also used to form an axial docking oil duct, an inner axial oil duct 6a, and an outer axial oil duct 6b, and to form a hub for communicating the winding oil duct 7a, the inter-cake oil duct 8a, the inner axial oil duct 6a, the outer axial oil duct 6b, and the axial docking oil duct with each other.

[0032] Each of the oil duct hub forming plates 8 includes at least one radially elongated hole 81 (i.e., an axially butt-jointed oil duct) provided on the oil duct hub forming plate 8. Since through it, two adjacent circumferentially wound oil ducts 7a can be butt-jointed and communicated with each other within the oil duct hub forming plate 8. The oil duct hub forming plate 8 is of an isosceles trapezoidal structure, its short base corresponds to the inner diameter end of the coil pancake 6, and its long base corresponds to the outer diameter end of the coil pancake 6. The radially elongated hole 81 is arranged along the radial direction of the coil pancake 6 and is communicated with the radially arranged oil duct 7a.

[0033] In the natural ester insulating oil transformer of the present invention, the oil duct hub forming plate 8 is of an isosceles trapezoidal structure, such that the widths of the inner end and the outer end of the inter-pancake oil duct 8a formed between two adjacent oil duct hub forming plates 8 are nearly the same, so that the natural ester insulating oil can penetrate deep into the coil pancake, which is beneficial to improving the heat exchange efficiency. Moreover, the oil duct hub forming plate 8 includes a radially elongated hole 81, and the radially elongated hole 81 is communicated with the axial oil duct, thus significantly reducing the blocking effect of the oil duct hub forming plate 8 on the axially flowing natural ester insulating oil, enabling the natural ester insulating oil to freely flow in the oil duct network formed by the axial oil duct and the inter-pancake oil duct, further improving the heat exchange effect of the transformer; and the natural ester insulating oil has a higher flash point and ignition point compared with the mineral insulating oil, which is also beneficial to improving the safety of the transformer.

[0034] Preferably, as Figure 1 and 7 shown, the fuel tank includes an inner box body and an outer box body. The outer box body includes a plurality of spaced-apart reinforcing irons 3 with a U-shaped cross-section welded to the outer side wall of the inner box body. Each reinforcing iron 3 extends from the top wall of the inner box body to the bottom wall of the inner box body. A reinforcing iron plate 1 welded to the two adjacent reinforcing irons 3 respectively is provided between two adjacent reinforcing irons 3. The outer box body can further improve the structural strength of the fuel tank, thereby improving the explosion-proof ability of the fuel tank and enhancing the safety of the natural ester insulating oil of the present invention. Further, as Figure 1 shown, a flange structure 2 is provided at the top end and the bottom end of each of the reinforcing irons 3; a cavity is formed by each of the reinforcing iron plates 1 and the two adjacent reinforcing irons 3 connected thereto, and flange interfaces 2 are also provided at the upper and lower ends of the cavity; each of the flange structures includes a flange and a cover plate cooperating with the flange; sand or asbestos material is filled in both the reinforcing iron 3 and the cavity, which can significantly reduce the operating noise of the natural ester insulating oil transformer of the present invention, and increase the self-weight of the transformer to improve its stability.

[0035] As Figure 1-7 shown, it is an embodiment of the explosion-proof insulating oil transformer using natural ester of the present invention.

[0036] As Figure 1 and 7As shown, the natural ester explosion-proof insulating oil transformer of the present invention includes an oil tank storing natural ester insulating oil and a plurality of coil cakes 6 (not shown in the figure) disposed in the oil tank and immersed in the natural ester insulating oil; as Figure 2 shown, in the same coil cake 6, between adjacent two coil layers (61, 62), there is a winding oil duct forming plate 7 for forming a winding oil duct 7a; as Figure 5 shown, between adjacent two coaxially stacked coil cakes 6, a plurality of oil duct hub forming plates 8 for forming an interlayer oil duct 8a are evenly distributed.

[0037] Preferably, as Figures 2-4 shown, it is an embodiment of the winding oil duct forming plate 7. When winding the coil, it is wound between two coil layers (61, 62) (as Figure 2 shown). It not only has the function of separating, supporting and positioning the outer coil layer 61 and the inner coil layer 62 of the coil cake 6, but also forms the winding oil duct 7a through it. Figure 2 Shown is the partial structure of the coil cake 6, which only shows the case of two coil layers (61, 62); it should be noted that the coil layers of the coil cake 6 of the present invention are not limited to 2 layers, and it can be multiple layers. However, no matter how many layers there are, the oil duct forming plate 7 and its winding oil duct 7a are always wound between two coil layers. The coil layer located outside the oil duct forming plate 7 (the side close to the outer side surface 64 of the coil cake 6) is defined as the outer coil layer 61, and the coil layer located inside the oil duct forming plate 7 (the side close to the inner side surface 63 of the coil cake 6) is defined as the inner coil layer 62; therefore, the inner / outer definition of the coil layer is relative to the inside / outside of the oil duct forming plate 7. In the case of more than 2 layers, for the same coil layer relative to the adjacent oil duct forming plate 7, its inner / outer definition is opposite. It should be understood that; if the coil cake 6 adopts a structure in which a single or multiple composite flat copper wires are wound to form one turn per layer of coil layer, then the winding oil duct 7a between two coil layers is the inter-turn oil duct; if the coil cake 6 adopts a structure in which each layer of coil layer is composed of multiple turns of copper wires, then the winding oil duct 7a between two coil layers is the interlayer oil duct. Obviously, whether it is the interlayer oil duct or the inter-turn oil duct, the beneficial characteristics and beneficial effects thereof are: the oil can be input into the coil layers and between turns; the insulating oil in the winding oil duct 7a can effectively convect the heat generated inside the coil cake 6 to the outside of the coil in time; thus, the temperature rise of the coil can be significantly reduced, the explosion-proof level of the transformer can be effectively improved, accidents such as explosion caused by temperature rise can be prevented, and various technical indicators and product performances related to the coil temperature rise can be effectively improved.

[0038] As Figure 3 and 4As shown, the winding oil duct forming plate 7 includes a base plate 70 and at least one row of support protrusions 71 provided on the base plate 70. Each support protrusion 71 is a conical boss, and its large-diameter end is connected to the base plate 70. Further, the winding oil duct forming plate 7 includes multiple rows of support protrusions 71, and the spacing between each row of support protrusions 71 is the same. Further, the column spacing between two adjacent rows of support protrusions 71 is the same as the spacing between the center lines of two adjacent turns of the same coil pancake 6, that is, two adjacent rows of support protrusions 71 are respectively matched with two adjacent turns of the coil. When the winding oil duct forming plate 7 is in use, as Figure 2 shown, the winding oil duct forming plate 7 is arranged between two adjacent layers of coils. The base plate 70 is attached to one layer of the coil layer (such as the inner coil layer 62), and the small-diameter end of the support protrusion 71 abuts against the other layer of the coil layer (such as the outer coil layer 61). Multiple support protrusions 71 are evenly distributed between the two layers of coil layers (61, 62) to form an inter-pancake oil duct 7a. Specifically, as Figure 2 shown, the base plate 70 is closely attached to the inner coil layer 62 located inside, and the small-diameter end of the support protrusion 71 abuts against the outer coil layer 61 located outside.

[0039] Preferably, the thickness of the base plate 70 is 0.5 - 1.0 mm, and the height of the support protrusion 71 is 5 - 15 mm.

[0040] It should be noted that the coil pancake 6 can be wound by a single or multiple composite flat copper wires. Then, the winding oil duct forming plate 7 with support protrusions arranged between adjacent single turns of copper wires includes a row of support protrusions 71 and a base plate 70, and the width of the base plate 70 is the same as the width of the flat copper wire.

[0041] Preferably, as Figures 5-6 shown, it is an embodiment of the oil duct hub forming plate 8.

[0042] As Figure 6 shown, the oil duct hub forming plate 8 is preferably an isosceles trapezoid structure, on which at least one radial long hole 81 is provided, and outer limit grooves 82 and inner limit grooves 83 are respectively provided on its long bottom side and short bottom side; an inner coil support bar (not shown in the figure) is provided inside the coil pancake 6, and an outer coil support bar (not shown in the figure) is provided outside. The inner limit groove 83 is in limit fit with the inner coil support bar, and the outer limit groove 82 is in limit fit with the outer coil support bar. Specifically, the oil duct hub forming plate 8 includes a radial long hole 81, and the axis of the radial long hole 81 coincides with the axis of the oil duct hub forming plate 8. As Figure 5As shown, when the oil duct hub forming plate 8 is in use, multiple oil duct hub forming plates 8 are evenly distributed between two coaxially stacked coil pancakes 6. The large bottom edge of each oil duct hub forming plate 8 corresponds to the outer diameter end of the coil pancake 6, and the small bottom edge corresponds to the inner diameter end of the coil pancake 6. Since the inner diameter of the coil pancake 6 is smaller than the outer diameter, if the oil duct hub forming plate 8 is of a rectangular structure, it will cause the inner end width of the inter-pancake oil duct 8a between two oil duct hub forming plates 8 to be smaller than the outer end width. The oil duct hub forming plate 8 of the present invention is an isosceles trapezoid, which offsets the above problem, making the inter-pancake oil duct 8a between two oil duct hub forming plates 8 nearly rectangular, so that the natural ester insulating oil can more easily enter the inside of the coil pancake 6, which is beneficial to improving the heat exchange efficiency; the multiple coil inner support bars are arranged on the outer side of the coil pancake 6 and are evenly distributed along its circumferential direction, and the multiple coil inner support bars are arranged on the inner side of the coil pancake 6 and are evenly distributed along its circumferential direction. The coil inner support bars, coil outer support bars and oil duct hub forming plates 8 correspond one by one. The coil inner support bars and coil outer support bars cooperate to reliably limit the oil duct hub forming plate 8 between adjacent coil pancakes, avoiding the situation that the oil duct hub forming plate 8 is displaced by external force and affecting the smoothness of the radial oil duct.

[0043] Preferably, as Figure 1 shown, it is an embodiment of the fuel tank.

[0044] The fuel tank includes an inner box body and an outer box body. The inner box body includes a top wall, a bottom wall and side walls arranged between the top wall and the bottom wall. The outer box body includes multiple U-shaped reinforcing irons 3 with cross-sections that are distributed at intervals and are welded to the side walls of the inner box body. Each reinforcing iron 3 extends from the top wall of the inner box body to the bottom wall of the inner box body. Between adjacent two reinforcing irons 3, there are reinforcing iron plates 1 respectively welded to the two reinforcing irons 3. Further, as Figure 1 shown, at the top and bottom ends of each reinforcing iron 3, there are flange assemblies 2; each reinforcing iron plate 1 and the two adjacent reinforcing irons 3 enclose a cavity, and at the top and bottom ends of the cavity, there are flange assemblies 2; each flange assembly 2 includes a flange fixedly arranged and a cover plate detachably matched with the flange; the reinforcing irons 3 and the cavities are filled with sand or asbestos materials. There are flange assemblies 2 at both ends of the reinforcing irons 3 and both ends of the cavities, which is convenient for adjusting the dosage of the filling materials therein or removing the filling materials (such as sand or asbestos materials).

[0045] It should be noted that for the flange assembly 2 arranged at the end of the reinforcing iron 3, its flange is welded to the end of the reinforcing iron 3 and the side wall of the inner box body, and there is an opening in the middle of the flange that communicates with the space enclosed by the reinforcing iron 3 and the side wall of the inner box body; for the flange assembly 2 arranged at the end of the cavity, its flange is welded to the reinforcing iron 3, the inner box body and the reinforcing iron plate 1, and there is an opening in the middle of the flange that communicates with the cavity.

[0046] Preferably, as Figure 1 and7 As shown, the fuel tank further includes two pressure relief structures 4, which are respectively arranged at both ends of the upper part of the fuel tank. One end of each pressure relief structure 4 is communicated with the inner tank of the fuel tank, and the other end is communicated with the fault oil sump. Further, the pressure relief structure 4 includes a pressure relief valve and a conduit. The pressure relief valve is communicated with and fixedly connected to the inner tank of the fuel tank, and the pressure relief valve is communicated with the fault oil sump through the conduit. Generally, only one pressure relief structure 4 is installed in an oil-immersed transformer. In this invention, considering that the molecular structure of natural ester insulating oil is larger than that of mineral insulating oil, and more types and amounts of gases are generated during decomposition in case of a fault. Therefore, when the pressure in the fuel tank exceeds the pressure warning value, the gas or natural ester insulating oil in the fuel tank can be quickly released through the two pressure relief structures 4 and enter the fault oil sump to ensure safety. When the transformer is working properly, the pressure relief structure 4 isolates the inside of the fuel tank from the external environment.

[0047] Preferably, the fuel tank further includes a quick-acting oil pressure relay 5 arranged on its upper part and communicated with the inner tank of the fuel tank. When the pressure in the fuel tank rises rapidly within a short time, the quick-acting oil pressure relay 5 can provide an alarm or trip signal.

[0048] To summarize, the characteristics of the explosion-proof insulating oil transformer of this invention are that the main structures different from the prior art for improving the explosion-proof level include: an explosion-proof oil duct structure, the core of which includes a winding oil duct 7a that can penetrate into the turns inside the coil, a cake-to-cake oil duct 8a, an inner axial oil duct 6a, an outer axial oil duct 6b and an axial docking oil duct that match the winding oil duct 7a, and an oil duct hub structure formed by an oil duct hub forming plate 8; an explosion-proof fuel tank structure, the core of which includes an inner tank and an outer tank, a U-shaped reinforcing iron 3 and a reinforcing iron plate 1, and a double-layer sealed fuel tank formed by connecting them according to the combination connection scheme given in this invention, the strength of which can reach a negative pressure of 10 - 30 Pa or a positive pressure of 100 - 150 Pa (the strength of the existing fuel tank is about a negative pressure of 133 Pa or a positive pressure of 80 - 100 Pa); a noise reduction and vibration damping structure, the core of which includes filling noise reduction and vibration damping materials (such as sand and / or asbestos), and an adjustable frequency flange assembly 2, which can adjust the filling amount of the noise reduction and vibration damping materials according to different noise spectra and resonance frequencies to achieve the best noise reduction and vibration damping effect; a pressure automatic protection structure, the core of which includes two pressure relief structures 4 and a quick-acting oil pressure relay 5, which can reduce the set value of pressure protection to 55 - 80 kPa (the existing transformer is generally 55 kPa), and can send an alarm or trip signal according to the rising speed of the pressure. Whether it is a cumulative pressure increase or a short-term pressure surge, it can be processed in time by releasing pressure and / or sending a signal.

[0049] It should be noted that Figures 1 to 7The given embodiments are designed based on the case of using natural ester as insulating oil. Specifically, it mainly aims at the problem of increased explosion risk caused by the high viscosity and poor fluidity of natural ester, and makes a series of explosion-proof improvements different from the prior art with the three major structures of oil ducts, oil tanks, and pressure protection as the breakthrough points. Therefore, when using natural ester with high combustion characteristics as insulating oil, excellent explosion-proof effects can be obtained. However, since the essential features of the above three major structural improvements lie in enhancing the depth and breadth of heat dissipation convection in the oil ducts, increasing the compressive strength of the oil tanks, and optimizing the automation level of pressure protection, when using mineral insulating oil, the above structural improvements can objectively also achieve remarkable explosion-proof effects. Or rather, the features of the present invention that are different from the prior art have the beneficial effect of improving the explosion-proof level regardless of whether natural ester insulating oil or mineral insulating oil is used. Therefore, the explosion-proof insulating oil transformer of the present invention is not limited to using natural ester insulating oil, and mineral insulating oil can also be used. It's just that using natural ester insulating oil has better explosion-proof effects than using mineral insulating oil.

[0050] It should be understood that among the above three major structural improvements, the improvement of the oil ducts is the most difficult. Because its shape and structure are complex and diverse, difficult to model, its forming principle has the characteristic of being composed of multiple components (usually cannot be constructed on one component through known processing methods), its manufacturing process not only involves part processing, but more involves complex assembly and fitting, and its technical effects involve many sensitive and non-intuitive fields such as thermotics, mechanics, and electromagnetics. Therefore, without creative labor, it is difficult to achieve the improvement results of the oil duct structure. The following combines Figures 2 to 6 the embodiments shown to further illustrate the specific implementation manners of the explosion-proof insulating oil transformer of the present invention with the focus on the improvement of the oil ducts. The explosion-proof insulating oil transformer of the present invention is not limited to the descriptions of the following embodiments.

[0051] See Figures 1 to 7, the explosion-proof insulating oil transformer of the present invention includes a plurality of coil cakes 6 installed in the oil tank and immersed in insulating oil. Of course, it also necessarily includes other well-known components of the transformer, such as an iron core (not shown in the figure). The coil cake 6 is wound into an annular structure by copper wire (preferably single or multiple composite flat copper wires) around a certain axis (not shown in the figure). Its internal structure necessarily includes multiple coil layers (61, 62), and its external structure necessarily includes an inner side 63, an outer side 64, and two radial end faces. Usually, the external dimension of a single coil cake 6 in the axial direction (the direction parallel to the axis) is smaller than its external dimension in the radial direction (the direction perpendicular to the axis). During assembly, a plurality of coil cakes 6 are stacked axially to form a set of windings. When the winding is sleeved on the iron core in place, the inner side 63 of each coil cake 6 is close to the iron core to form electromagnetic induction between them. During the operation of the transformer, the electromagnetic induction causes the coil cake 6 and the iron core to generate not only heat but also electromagnetic force (which may cause vibration and failure of stressed components). Therefore, for the oil duct design around the coil cake 6 and the iron core, it cannot be considered only from the heat dissipation effect, but also the electromagnetic induction effect, the support and electromagnetic force effect, and the insulation isolation effect, etc. Existing transformers use structures such as pads and spacers, and most of them cannot take into account the heat dissipation of the oil duct. The existing solid components such as pads and spacers are usually structures that are contradictory to the oil duct function. They not only do not have a heat dissipation effect but even have problems affecting the convection of insulating oil.

[0052] A beneficial feature of the oil duct structure of the present invention is that a circumferential oil duct 7a is provided between the outer wire layer 61 and the inner coil layer 62 of the same coil pancake 6. It is distributed on the entire large curved surface formed by the axial and circumferential directions between the inner and outer coil layers (62, 61), and is fully penetrated on this large curved surface, that is, the circumferential oil duct 7a is not only axially penetrated but also circumferentially penetrated on the entire large curved surface, so that the insulating oil in the circumferential oil duct 7a can flow unobstructedly in the radial and circumferential directions. The circumferential direction mentioned here refers to the direction around the axis of the coil pancake 6; in the preferentially adopted structural mode where a single-layer coil layer wound by a single or multiple composite flat copper wires is one turn, the circumferential oil duct 7a is an inter-turn oil duct, and the cross-sectional shape in the radial direction is an open spiral. The insulating oil in it can not only flow axially but also flow along the entire spiral; of course, it does not exclude the structural mode where each coil layer is composed of multiple turns of copper wires. In this mode, the circumferential oil duct 7a is an inter-layer oil duct, and the cross-sectional shape in the radial direction is an annular line. The insulating oil in it can not only flow axially but also flow around along the entire annular line. The oil ducts formed by the prior art usually adopt axial oil duct spacers, spacer curtains and other methods. The key difference between it and the circumferential oil duct 7a of the present invention is that: the prior art can only form oil ducts between different coil layers, while the circumferential oil duct 7a can not only be arranged between different coil layers, but also between the same coil layers, and can also be arranged between the turns of the coil; the oil ducts formed by the prior art are discontinuous in the circumferential direction, and the insulating oil in the oil ducts can only flow axially and cannot flow circumferentially, while the circumferential oil duct 7a is fully penetrated on the entire large curved surface in its circumferential direction, and the insulating oil in the oil duct can not only flow axially but also flow circumferentially. Obviously, compared with the prior art, the circumferential oil duct 7a of the present invention has substantial differences in its distribution, orientation and the convection of insulating oil in it, and these differences enable it to have remarkable effects such as reducing the temperature of the coil core, balancing the temperature difference inside the transformer, and accelerating the heat dissipation speed.

[0053] The specific structure of the circumferential oil duct 7a described above can have various implementation modes. A preferred mode is the oil duct structure constructed by the circumferential oil duct forming plate 7, which includes two forms: a convex forming structure and a concave forming structure.

[0054] Regarding the convex forming structure form of the circumferential oil duct 7a, as Figures 2 to 4As shown in the figure: A winding direction oil duct forming plate 7 is further provided between the outer wire layer 61 and the inner coil layer 62 of the coil pancake 6. The winding direction oil duct 7a is formed by a plurality of support protrusions 71 provided on the winding direction oil duct forming plate 7. The winding direction oil duct forming plate 7 includes a substrate 70 and a plurality of support protrusions 71 formed on the substrate 70. The spaced gaps between the support protrusions 71 form the winding direction oil duct 7a. The spaced gaps are distributed in the radial and axial directions throughout the substrate 70 and are fully penetrated on the substrate 70. By "fully penetrated", it means that the spaced gaps not only penetrate the entire substrate 70, but also reach the contour edge 700 of the winding direction oil duct forming plate 7, so that the insulating oil in the spaced gaps can flow smoothly with the insulating oil outside the contour edge 700 (that is, outside the coil pancake 6). The support protrusions 71 are constructed on the entire substrate 70 by known processing methods (such as adhesive connection), and its specific structure can have various forms. A preferred form is as follows Figure 2 and Figure 3 As shown in the figure: The plurality of support protrusions 71 forming the winding direction oil duct 7a are constructed on the winding direction oil duct forming plate 7 in an equally spaced distribution manner. The outer shape of each support protrusion 71 is a frustum of a cone. Its large diameter end is fixed to the substrate 70, and its small diameter end 7c abuts and supports the outer wire layer 61 or the inner coil layer 62 of the coil pancake 6. That is, after the winding direction oil duct forming plate 7 is wound between the outer wire layer 61 and the inner coil layer 62, the small diameter ends 7c of the plurality of support protrusions 71 respectively abut and support the outer wire layer 61, and the large support surface 7b of the substrate 70 abuts and supports the inner coil layer 62 (as shown in Figure 2 ); or the small diameter ends 7c respectively abut and support the inner coil layer 62, and the large support surface 7b of the substrate 70 abuts and supports the outer wire layer 61 (not shown in the figure). Thus, it can be seen that the winding direction oil duct forming plate 7 is not only used to construct the winding direction oil duct 7a, but also has multiple functions such as insulation separation and radial support between the coil layers.

[0055] The recessed forming structure of the circumferential oil duct 7a is not shown in the drawings. Different from the protruding forming structure, the circumferential oil duct 7a is directly formed on the circumferential oil duct forming plate 7 by a known forming method (such as die pressing). That is to say, the circumferential oil duct 7a is a recess pressed on the circumferential oil duct forming plate 7. A circumferential oil duct forming plate 7 is provided between the outer wire layer 61 and the inner coil layer 62 of the coil cake 6. The circumferential oil duct forming plate 7 includes two supporting large surfaces, and a recess serving as the circumferential oil duct 7a is formed on one and / or the other of the supporting large surfaces. The recess is distributed over the entire supporting large surface and penetrates through the entire supporting large surface, that is, the recess not only penetrates through the entire supporting large surface but also reaches the contour edge 700 of the circumferential oil duct forming plate 7, so that the insulating oil in the recess can flow smoothly with the insulating oil outside the contour edge 700 (i.e., outside the coil cake 6). When the circumferential oil duct forming plate 7 is wound between the outer wire layer 61 and the inner coil layer 62, the two supporting large surfaces are respectively in contact with and support the outer wire layer 61 and the inner coil layer 62, and an oil duct gap is formed between the recess and the outer wire layer 61 and / or the inner coil layer 62. Thus, in the recessed forming structure, the circumferential oil duct forming plate 7 also has multiple functions of constructing an insulating separation and radial support between the circumferential oil duct 7a and the coil layer.

[0056] Whether it is the protruding forming structure or the recessed forming structure, the length (dimension along the circumferential direction) and width (dimension along the radial direction) of the circumferential oil duct forming plate 7 are the same. In the case of using different conductors and turn / layer structures (the number of turns per layer), the length and width of the circumferential oil duct forming plate 7 vary with the conductor structure. Specifically, for the circumferential oil duct forming 7 that constructs the circumferential oil duct 7a, its length matches the circumferential length of the outer wire layer 61 or the inner coil layer 62 of the coil cake 6. That is: in a turn / layer structure with only one turn per layer, the circumferential length of its outer wire layer 61 or inner coil layer 62 is the length of the conductor, and the length of the circumferential oil duct forming plate 7 should be matched with reference to the length of the conductor; in a turn / layer structure with multiple turns per layer, the length of the circumferential oil duct forming plate 7 should be matched with reference to the circumference of the layer. Of course, the matching is also related to factors such as the winding tightness, etc., and can be specifically determined according to the turn / layer structure and known matching methods. Preferably, the coil cake 6 is wound by a single flat copper wire or multiple composite flat copper wires, and the circumferential oil duct 7a between the outer wire layer 61 and the inner coil layer 62 is an inter-turn oil duct between two adjacent turns of flat copper wires of the same winding. The width of the circumferential oil duct forming plate 7 that constructs this inter-turn oil duct is equal to the width of the flat copper wire. Of course, it is not excluded that the coil cake 6 is wound by copper wires, and the circumferential oil duct 7a between the outer wire layer 61 and the inner coil layer 62 is an inter-layer oil duct between two adjacent layers of copper wires of the same winding. The width of the circumferential oil duct forming plate 7 that constructs this inter-layer oil duct is equal to the axial height of the coil cake 6.

[0057] Another beneficial feature of the oil duct structure of the present invention is that a plurality of inter-pancake oil ducts 8a are provided between two adjacent coil pancakes 6. They are evenly distributed along the radial end faces of the coil pancakes 6, and each inter-pancake oil duct 8a extends along the end face to the outside of the inner side face 63 and the outer side face 64 of the coil pancake 6, so that the insulating oil in the inter-pancake oil duct 8a can flow radially along the end face to the outside of the coil pancake 6. Inner axial oil ducts 6a and outer axial oil ducts 6b are respectively provided on the inner side face 63 and the outer side face 64 of each coil pancake 6, and each inter-pancake oil duct 8a communicates with the circumferential oil duct 7a, the inner axial oil duct 6a and the outer axial oil duct 6b respectively. Or rather, a gap serving as the inner axial oil duct 6a is provided in the area outside the coil pancake 6 near the inner side face 63 (that is, the area between the inner side face 63 and the iron core), and a gap serving as the outer axial oil duct 6b is also provided in the area outside the coil pancake 6 close to the outer side face 64. The coil pancakes 6 are stacked and installed axially. This installation enables the inner axial oil ducts 6a of the coil pancakes 6 to communicate with each other axially, and the outer axial oil ducts 6b of the coil pancakes 6 to communicate with each other axially. Moreover, since each inter-pancake oil duct 8a extends to the outside of the inner side face 63 and the outer side face 64 of the coil pancake 6, the inner axial oil ducts 6a and the outer axial oil ducts 6b respectively communicate with the inter-pancake oil ducts 8a between the corresponding coil pancakes 6 axially. It should be understood that since the circumferential oil duct 7a is distributed on the entire large curved surface formed axially and circumferentially between the inner and outer coil layers (62, 61) and is fully penetrated on this large curved surface, when the coil pancakes 6 are stacked and installed axially, the circumferential oil ducts 7a between the layers (turns) will necessarily intersect with the corresponding inter-pancake oil ducts 8a, that is, the circumferential oil ducts 7a will necessarily communicate with the corresponding inter-pancake oil ducts 8a, so that the circumferential oil ducts 7a, the inter-pancake oil ducts 8a, the inner axial oil ducts 6a and the outer axial oil ducts 6b form an oil duct network that intersects with each other in the circumferential, radial and axial directions. And based on the principle of liquid convection, the insulating oil in the oil duct network can form smooth convection in the circumferential, radial and axial directions, so as to effectively improve the heat dissipation performance of the transformer, reduce the temperature inside the coil, balance the temperature difference inside the transformer, and thus improve the explosion-proof level.

[0058] The specific structure of the inter-pancake oil duct 8a can have various implementation manners. A preferred manner is as Figure 4 and Figure 5As shown in the figure: the inter-pancake oil duct 8a is formed by arranging a plurality of oil duct hub forming plates 8 between two adjacent coil pancakes 6. Each oil duct hub forming plate 8 is respectively supported between the radial end faces of two adjacent coil pancakes 6, and there is a gap between two adjacent oil duct hub forming plates 8. Each gap respectively forms a void between two adjacent coil pancakes 6, and this void constitutes the inter-pancake oil duct 8; each void is respectively communicated with the circumferential oil ducts 7a of the two coil pancakes 6 where it is located, and respectively intersects with the inner side surface 63 and the outer side surface 64 of the two coil pancakes 6 where it is located. The prior art usually forms oil ducts by various methods such as pads and guiding partition plates arranged along the radial direction of the coil. Its defects are as follows: the various pads and guiding partition plates used in the prior art are numerous and occupy a large space, so it is impossible to leave enough space for the oil duct, or in other words, it does not conform to the optimization design principle of maximizing the oil duct space; the structure is complex, which makes the oil ducts composed of these pads and partition plates have too many twists and turns inside the coil, hindering the flow rate of the insulating oil and not conforming to the principle of smooth and fast flow required for temperature reduction; the current situation and distribution of various pads and guiding partition plates are unreasonable, making the oil duct narrow inside and wide outside, and this structure will exacerbate the uneven temperature of the coil core. The beneficial characteristics of the oil duct hub forming plate 8 of the present invention are as follows: only one structure with the same shape and size is used, which is easy to process, has low cost and simple structure with a small number. It can not only have a reliable and stable axial support function between pancakes (between coil pancakes 6), but also use it to construct the inter-pancake oil duct 8a, the axial oil ducts (6a, 6b) and the axial docking oil duct, and form a hub that can make various oil ducts communicate with each other around it. In addition, it can make the inter-pancake oil duct 8a have a uniform radial distribution and the same width inside and outside.

[0059] As can be seen from above: The inter-pancake oil duct 8a formed by the oil duct hub forming plate 8 respectively supported between the radial end faces of two adjacent coil pancakes 6 can be directly in close contact with the radial end faces of two adjacent coil pancakes 6, and a relatively wide oil storage gap can be formed; Since the inter-pancake oil duct 8a is assembled by the oil duct hub forming plates 8 distributed at intervals respectively supported between the radial end faces of two adjacent coil pancakes 6, an optimized structure in which the inter-pancake oil duct 8a intersects and communicates with the circumferential oil duct 7a can be obtained through this assembly, and an optimized structure of the inner axial oil duct 6a and the outer axial oil duct 6b that can be directly in close contact with the inner side surface 63 and the outer side surface 64 of two adjacent coil pancakes 6 can also be obtained. This optimized structure is as follows: The inner axial oil duct 6a and the outer axial oil duct 6b are respectively composed of a plurality of axially arranged inner support bars (not shown in the figure), a plurality of outer support bars (not shown in the figure) and a plurality of oil duct hub forming plates 8 arranged between two adjacent coil pancakes 6; Each oil duct hub forming plate 8 includes an inner bottom edge corresponding and matching with the inner side surface 63 of the coil pancake 6 and an outer bottom edge corresponding and matching with the outer side surface 64 of the coil pancake 6; An outer limit groove 82 is provided on the outer bottom edge, which is fixedly matched with the outer support bar; An inner limit groove 83 is provided on the inner bottom edge, which is fixedly matched with the inner support bar; Through the fixed cooperation and assembly of the oil duct hub forming plate 8 with the inner support bar and the outer support bar, the axially stacked coil pancakes 6 are positioned axially and radially, and an inner gap used as the inner axial oil duct 6a is formed between two adjacent inner support bars, and an outer gap used as the outer axial oil duct 6b is formed between two adjacent outer support bars. Of course, the coil assembly (not shown in the figure) formed by axially stacking and installing a plurality of coil pancakes 6 by a plurality of oil duct hub forming plates 8, inner support bars and outer support bars still needs to be installed inside the transformer. This installation structure can adopt any known structure. However, no matter what structure it is, the radial positioning of the coil assembly needs to be realized by the inner support bar and / or the outer support bar abutting against other known components (such as insulating paper tubes, iron cores, etc., not shown in the figure). Since the design of the radial thickness of the inner support bar and the outer support bar takes into account the requirements of the axial oil ducts (6a, 6b), after the coil assembly is installed in place, an inner gap that can be used as the inner axial oil duct 6a will necessarily be formed between the inner side surface 63 of each coil pancake 6 and the component abutting against the inner support bar, and / or, an outer gap that can be used as the outer axial oil duct 6b will necessarily be formed between the outer side surface 64 of each coil pancake 6 and the component abutting against the outer support bar. Thus, it can be seen that: The inner axial oil duct 6a of the present invention is formed by the inner support bar, the inner side surface 63 of the coil pancake 6 and the inner gap surrounded by the component abutting against the inner support bar. It is in close contact with the coil pancake 6 and intersects and communicates with the inter-pancake oil ducts 8a of each layer; Similarly, the outer axial oil duct 6b is formed by the outer support bar, the outer side surface 64 of the coil pancake 6 and the outer gap surrounded by the component abutting against the outer support bar. It is in close contact with the coil pancake 6 and intersects and communicates with the inter-pancake oil ducts 8a of each layer.

[0060] Another beneficial feature of the oil duct structure of the present invention lies in the other two special structures of the oil duct hub forming plate 8. One of the special structures is as shown in Figure 6 : A plurality of oil duct hub forming plates 8 for constructing the inter-pancake oil duct 8a are provided between two adjacent coil pancakes 6. At least one radial long hole 81 for docking the circumferential oil duct 7a is provided on each oil duct hub forming plate 8, and an axial docking oil duct for axially connecting adjacent circumferential oil ducts 7a is formed within the oil duct hub forming plate 8. For various supporting members such as spacers and guiding partition plates used in existing coils, since insulating materials are required, and insulating materials usually have poor thermal conductivity, it is often difficult for the heat at the contact parts between the coil and these supporting members to dissipate, resulting in the problem of uneven coil temperature. By providing an axial docking oil duct on the oil duct hub forming plate 8, the present invention can not only dock the circumferential oil ducts 7a to accelerate the convection speed of the circumferential oil ducts 7a and improve the heat dissipation efficiency of the circumferential oil ducts 7a, but also timely take away the heat at the contact and supporting parts between the oil duct hub forming plate 8 and the coil pancake 6, effectively improving the problem of uneven coil temperature. In summary, the oil duct hub forming plate 8 of the present invention is different from the existing supporting members in that: a plurality of oil duct hub forming plates 8 are provided between two adjacent coil pancakes 6, and the oil duct hub forming plates 8 together form the inter-pancake oil duct 8a, the inner axial oil duct 6a, the outer axial oil duct 6b, and the axial docking oil duct, and each oil duct hub forming plate 8 respectively forms a hub for the mutual connection between the circumferential oil duct 7a, the inter-pancake oil duct 8a, the inner axial oil duct 6a, the outer axial oil duct 6b, and the axial docking oil duct. In other words, the oil duct hub forming plate 8 is a link for connecting the circumferential oil duct 7a, the inter-pancake oil duct 8a, the inner axial oil duct 6a, the outer axial oil duct 6b, and the axial docking oil duct.

[0061] Another special structure of the oil duct hub forming plate 8 of the present invention is as shown in Figure 6 : The oil duct hub forming plate 8 adopts a trapezoidal structure, and its outer bottom side is larger than the inner bottom side, so that the gap between two adjacent oil duct hub forming plates 8 is a parallelogram. The gap is the inter-pancake oil duct 8a, and its parallelogram structure overcomes the problem of the inner narrow and outer wide of the radial oil duct existing in the existing structure, can effectively improve the overall convection heat dissipation efficiency of the transformer, and can effectively improve the problem of uneven temperature of the coil pancake 6.

[0062] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. A natural ester insulating oil transformer, which comprises an oil tank storing natural ester insulating oil and a plurality of coil pancakes (6) arranged in the oil tank and immersed in the natural ester insulating oil; It is characterized in that: In the same coil pancake (6), a winding oil duct forming plate (7) for forming a winding oil duct (7a) is provided between adjacent two coil layers; a plurality of oil duct hub forming plates (8) for forming inter-pancake oil ducts (8a) are evenly distributed between two adjacent coil pancakes (6) stacked coaxially; Each oil duct hub forming plate (8) comprises at least one radial long hole (81) connecting with the winding oil duct (7a). The oil duct hub forming plate (8) is of an isosceles trapezoid structure, its short bottom edge corresponds to the inner diameter end of the coil pancake (6), its long bottom edge corresponds to the outer diameter end of the coil pancake (6), the radial long hole (81) is arranged along the radial direction of the coil pancake (6) and communicates with the winding oil duct (7a); a plurality of inter-pancake oil ducts (8a) are arranged between two adjacent coil pancakes (6), and the plurality of inter-pancake oil ducts (8a) are respectively distributed along the radial end faces of the coil pancakes (6). Each inter-pancake oil duct (8a) extends to the outside of the inner side face (63) and the outer side face (64) of the coil pancake (6). An inner axial oil duct (6a) and an outer axial oil duct (6b) are respectively arranged on the inner side face (63) and the outer side face (64) of each coil pancake (6). Each inter-pancake oil duct (8a) communicates with the winding oil duct (7a), the inner axial oil duct (6a) and the outer axial oil duct (6b) respectively.

2. The natural ester insulating oil transformer according to claim 1, wherein: The winding oil duct forming plate (7) comprises a substrate (70) and a plurality of columns of support protrusion arrays arranged on the substrate (70). Each support protrusion array comprises a plurality of support protrusions (71) evenly spaced apart. Each support protrusion (71) is a conical boss, and its large diameter end is connected with the substrate (70); the winding oil duct forming plate (7) is arranged between two adjacent coils, the substrate (70) is attached to one of the coil layers, the small diameter end of the support protrusion (71) abuts against the other coil layer, and the plurality of support protrusions (71) are evenly distributed between the two coil layers to form a winding oil duct (7a).

3. The natural ester insulating oil transformer according to claim 2, characterized in that: The thickness of the substrate (70) is 0.5 - 1.0 mm, and the height of the support protrusion (71) is 5 - 15 mm.

4. The natural ester insulating oil transformer according to claim 2, wherein: The coil pancake (6) is wound by flat copper wires. The winding oil duct (7a) formed by the winding oil duct forming plate (7) between two adjacent coil layers is an inter-turn oil duct between single-turn copper wires, which comprises a substrate (70) and a plurality of columns of support protrusions (71), and the width of the substrate (70) is the same as the width of the flat copper wire.

5. The natural ester insulating oil transformer according to claim 1, characterized in that: The oil duct hub forming plate (8) further comprises an outer limiting groove (82) and an inner limiting groove (83) respectively arranged on the long bottom edge and the short bottom edge; an inner coil support bar is arranged inside the coil pancake (6), and an outer coil support bar is arranged outside the coil pancake (6). The inner limiting groove (83) is in limiting cooperation with the inner coil support bar, and the outer limiting groove (82) is in limiting cooperation with the outer coil support bar.

6. The natural ester insulating oil transformer according to claim 1, wherein: The fuel tank includes an inner box body and an outer box body. The inner box body includes a top wall, a bottom wall, and side walls disposed between the top wall and the bottom wall. The outer box body includes a plurality of reinforcing irons (3) that are welded to the side walls of the inner box body, are spaced apart from each other, and have a U-shaped cross section. Each reinforcing iron (3) extends from the top wall of the inner box body to the bottom wall of the inner box body. A reinforcing iron plate (1) that is welded to the two adjacent reinforcing irons (3) respectively is provided between two adjacent reinforcing irons (3).

7. The natural ester insulating oil transformer according to claim 6, characterized in that: A flange assembly (2) is provided at the top and bottom of each reinforcing iron (3); a cavity is formed by each reinforcing iron plate (1) and the two adjacent reinforcing irons (3) thereto, and a flange assembly (2) is provided at the top and bottom of the cavity; each flange assembly (2) includes a flange and a cover plate that is correspondingly matched with the flange; the reinforcing irons (3) and the cavities are filled with sand or asbestos materials.

8. The natural ester insulating oil transformer according to claim 1, wherein: The fuel tank further includes two pressure release structures (4), which are respectively provided at two ends of the upper part of the fuel tank. One end of each pressure release structure (4) communicates with the inner box body of the fuel tank, and the other end communicates with a fault oil sump.

9. The natural ester insulating oil transformer according to claim 1 or 8, characterized in that: The fuel tank further includes a quick-acting oil pressure relay (5) that is provided at its upper part and communicates with the inner box body of the fuel tank.

10. The natural ester insulating oil transformer according to claim 1, characterized in that: The circumferential oil duct (7a) is distributed on a large curved surface formed by the axial and circumferential directions between adjacent two coil layers, and the circumferential oil duct (7a) not only penetrates axially but also penetrates circumferentially on the large curved surface.

11. The natural ester insulating oil transformer according to claim 10, wherein: The circumferential oil duct (7a) is formed by a plurality of support protrusions (71) provided on a circumferential oil duct forming plate (7); the circumferential oil duct forming plate (7) includes a substrate (70) and a plurality of support protrusions (71) formed thereon. The spaced gaps between the support protrusions (71) form the circumferential oil duct (7a). The spaced gaps are distributed in the radial and axial directions on the entire substrate (70) and penetrate through the entire substrate (70).

12. The natural ester insulating oil transformer according to claim 1, characterized in that: The inner axial oil duct (6a) and the outer axial oil duct (6b) are respectively constituted by a plurality of inner support bars, a plurality of outer support bars that are axially arranged, and a plurality of oil duct hub forming plates (8) disposed between two adjacent coil cakes (6); each oil duct hub forming plate (8) includes an inner bottom edge that correspondingly matches the inner side surface (63) of the coil cake (6) and an outer bottom edge that correspondingly matches the outer side surface (64) of the coil cake (6); an outer limit groove (82) is provided on the outer bottom edge for fixedly cooperating with the outer support bar; an inner limit groove (83) is provided on the inner bottom edge for fixedly cooperating with the inner support bar; through the fixed cooperation and assembly of the oil duct hub forming plate (8) with the inner support bar and the outer support bar, the axially stacked coil cakes (6) are positioned axially and radially, and an inner gap serving as the inner axial oil duct (6a) is formed between two adjacent inner support bars, and an outer gap serving as the outer axial oil duct (6b) is formed between two adjacent outer support bars.

13. A natural ester insulating oil transformer according to claim 12, characterized in that: A plurality of oil duct hub forming plates (8) are arranged between two adjacent coil pancakes (6). The oil duct hub forming plates (8) together form an inter-pancake oil duct (8a), an inner axial oil duct (6a), an outer axial oil duct (6b), and an axial docking oil duct formed by radial long holes (81). Each oil duct hub forming plate (8) respectively forms a hub where the circumferential oil duct (7a), the inter-pancake oil duct (8a), the inner axial oil duct (6a), the outer axial oil duct (6b), and the axial docking oil duct communicate with each other.

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