Low-voltage double-layer winding structure and transformer

Abstract

The invention relates to the technical field of transformers, in particular to a low-voltage double-layer winding structure and a transformer wherein the low-voltage double-layer winding structure comprises an inner paper tube, an inner winding, a plurality of oil duct stays, an insulating tube and an outer winding; the plurality of oil duct stays are arranged between the inner-layer winding and the outer-layer winding, one surface, deviating from the inner-layer winding, of each oil duct stay is provided with a lap joint groove in the thickness direction of the oil duct stay, the insulating cylinder is in lap joint with the lap joint grooves of the plurality of oil duct stays, and the groove walls, corresponding to the lap joint grooves, of the oil duct stays are attached to the side surface of the insulating cylinder; the lap joint grooves are arranged corresponding to the breakdown risk area of the inner layer winding and the breakdown risk area of the outer layer winding. The radial size of the outer layer winding is effectively reduced, the coil consumption is reduced, the production cost is reduced, and the technical problems that the coil consumption is large, the production cost is high, the overall winding structure occupies a large space, and the size of the transformer is increased due to the fact that the radial size of the outer layer winding of an existing double-layer winding structure is too large are solved.

Description

Technical Field

[0001] The invention relates to the technical field of transformers, and in particular to a low-voltage double-layer winding structure and a transformer. Background Art

[0002] Double-layer winding is a widely used low-voltage winding structure, which is mainly composed of an inner winding and an outer winding, both of which are usually continuously wound from the same wire. Under the action of electromagnetic induction, each turn of the winding will induce an electromotive force, but due to the different positions of the turns in the winding, the magnitude of the electromotive force induced by them is different, and the voltage generated is also different. Between the turns of the same winding, the voltage is distributed in a gradient along the axial direction of the winding. At this time, an operating voltage difference will appear between the two symmetrical points of the same amplitude of the inner and outer windings, and the operating voltage difference between the symmetrical points at different positions gradually increases or decreases along the axial direction of the winding. However, if the operating voltage difference reaches or exceeds 5kV, if the insulation strength between the inner and outer windings is insufficient, there is a risk of operating breakdown. At this time, in order to enhance the insulation strength between the windings, an insulating tube will be set between the inner and outer windings to improve the electrical isolation effect between the windings. On the other hand, in order to optimize the heat dissipation performance, double-layer windings often use a design of a heat dissipation oil channel constructed with support bars, so that the heat of the coil can be effectively brought out through the transformer oil flowing in the heat dissipation oil channel, thereby achieving heat exchange with the external environment and improving heat dissipation efficiency.

[0003] In the existing double-layer winding, two layers of heat dissipation oil channels and an insulating cylinder are usually required between the inner winding and the outer winding, and the winding structure is sequentially provided with an inner paper cylinder, an inner winding, an inner support bar, an insulating cylinder, an outer support bar and an outer winding from the inside to the outside. However, the radial dimension of the outer winding of this double-layer winding structure is too large, resulting in a large amount of coils and high production costs, and the overall winding structure occupies a large space, resulting in an increase in the size of the transformer. Summary of the invention

[0004] The main purpose of the present invention is to provide a low-voltage double-layer winding structure that can simultaneously meet the requirements of electrical safety standards and winding heat dissipation needs, improve space utilization, effectively reduce the radial size of the outer winding, and the overall structure is reasonable and compact, occupies little space, reduces the amount of coils, and reduces production costs. It solves the technical problems that the radial size of the outer winding of the existing double-layer winding structure is too large, resulting in a large amount of coils and high production costs, and the overall winding structure occupies a large space, resulting in an increase in the size of the transformer.

[0005] Another object of the present invention is to provide a transformer using the above-mentioned low-voltage double-layer winding structure, which effectively reduces the size of the transformer and can reduce production costs. It solves the technical problems that the outer winding of the existing double-layer winding structure has an excessively large radial dimension, resulting in a large amount of coils and high production costs, and the overall winding structure occupies a large space, resulting in an increase in the size of the transformer.

[0006] To achieve the above-mentioned object, the low-voltage double-layer winding structure proposed in the present invention is applied to a transformer, comprising an inner paper cylinder, an inner winding, a plurality of oil channel stays, an insulating cylinder and an outer winding;

[0007] The inner layer winding is arranged around the inner paper tube, the outer layer winding is arranged on the side of the inner layer winding away from the inner paper tube, the insulating tube is arranged on the side of the outer layer winding close to the inner paper tube, and a plurality of oil channel stays are arranged between the inner layer winding and the outer layer winding, and each of the oil channel stays is extended along the axial direction of the inner paper tube to form a heat dissipation oil channel between the inner layer winding and the outer layer winding;

[0008] Each of the oil channel struts has a lap groove on one side away from the inner layer winding along its thickness direction, the height of the insulating tube is adapted to the length of the lap groove, the insulating tube is lapped on the lap grooves of a plurality of the oil channel struts, and the groove wall of the oil channel strut corresponding to the lap groove is in contact with the side surface of the insulating tube;

[0009] The inner winding and the outer winding both include a non-breakdown risk area and a breakdown risk area, and the overlapping grooves are arranged corresponding to the breakdown risk area of ​​the inner winding and the breakdown risk area of ​​the outer winding.

[0010] Optionally, the height of the insulating tube is half of the height of the inner paper tube, and the length of the oil channel support bar is the same as the height of the inner paper tube.

[0011] Optionally, the thickness of a plurality of the oil channel struts is the same, and the oil channel struts are evenly arranged along the circumference of the inner layer winding.

[0012] Optionally, the thickness of the oil channel support strip is 4mm-8mm.

[0013] Optionally, the thickness of the oil channel support strip is 6 mm.

[0014] Optionally, the depth of the overlapping groove is greater than or equal to the thickness of the insulating tube.

[0015] Optionally, the thickness of the insulating tube is 1.5 mm-2 mm.

[0016] Optionally, the height of the inner paper tube = the winding height of the inner winding + the insulation height of the upper end of the inner winding + the insulation height of the lower end of the inner winding; the insulation height of the upper end of the inner winding is the distance between the upper end surface of the inner winding and the upper end surface of the oil channel support bar; the insulation height of the lower end of the inner winding is the distance between the lower end surface of the inner winding and the lower end surface of the oil channel support bar;

[0017] Or, the height of the inner paper tube = the winding height of the outer winding + the insulation height of the upper end of the outer winding + the insulation height of the lower end of the outer winding; the insulation height of the upper end of the outer winding is the distance between the upper end surface of the outer winding and the upper end surface of the oil channel support; the insulation height of the lower end of the outer winding is the distance between the lower end surface of the outer winding and the lower end surface of the oil channel support.

[0018] The present invention also provides a transformer, comprising any one of the low-voltage double-layer winding structures described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. In the present low-voltage double-layer winding structure, both the inner winding and the outer winding include a non-breakdown risk area and a breakdown risk area. According to the voltage gradient distribution characteristics of the layer winding, each oil channel support bar is provided with an overlap groove along its own thickness direction on the side away from the inner winding. By correspondingly arranging the overlap grooves in the two breakdown risk areas, an oil channel support bar and an insulating tube are arranged between the breakdown risk area of ​​the inner winding and the breakdown risk area of ​​the outer winding. The insulating tube is used to protect the two breakdown risk areas, effectively improving the insulation strength between the two and avoiding the occurrence of operational breakdown. However, since the insulation strength between the non-breakdown risk area of ​​the inner winding and the non-breakdown risk area of ​​the outer winding has reached the requirements of the electrical safety standards and operational breakdown will not occur, no insulating tube is arranged between the two non-breakdown risk areas, only oil channel support bars are arranged. The present low-voltage double-layer winding structure has high overall insulation strength, meets the requirements of the electrical safety standards, and can operate safely.

[0021] 2. In this low-voltage double-layer winding structure, the oil channel support bars are partially grooved, and the two breakdown risk areas correspond to the overlapping grooves, while the oil channel support bars corresponding to the two non-breakdown risk areas are not grooved. Therefore, the oil channel support bars corresponding to the two non-breakdown risk areas have a larger thickness, which can further increase the thickness of the heat dissipation oil channel and improve the overall heat dissipation performance. It can ensure that the heat dissipation requirements between the inner winding and the outer winding are met. Therefore, this low-voltage double-layer winding structure can meet the electrical safety standards and the winding heat dissipation requirements at the same time.

[0022] 3. In addition, by making local grooves on the oil channel support bars, the overlapping grooves with a certain depth can be used to place the insulating tube, so that the insulating tube will not occupy an extra layer of space, effectively improving the space utilization rate. With this low-voltage double-layer winding structure, the coils can be arranged more closely during the layer winding, effectively reducing the radial size of the outer winding. This low-voltage double-layer winding structure has the characteristics of reasonable and compact overall structure, small space occupation and high short-circuit resistance. Moreover, reducing the radial size of the outer winding can reduce the amount of coils used, reduce the consumption of raw materials, thereby reducing production costs and achieving better economy. Therefore, this low-voltage double-layer winding structure takes into account economy, electrical safety and heat dissipation performance at the same time.

[0023] 4. In addition, in the existing winding structure, one layer of heat dissipation oil channel corresponds to one winding, that is, one layer of heat dissipation oil channel can only be used to achieve heat dissipation of one winding, while the low-voltage double-layer winding structure adopts one layer of heat dissipation oil channel to achieve simultaneous heat dissipation of the inner winding and the outer winding. Therefore, the low-voltage double-layer winding structure also has the advantage of high heat dissipation utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A top view of a low voltage double-layer winding structure according to an embodiment of the present invention;

[0025] Figure 2 for Figure 1 The enlarged view of point A in the middle;

[0026] Figure 3 for Figure 1 Schematic diagram of the structure after hiding the outer winding;

[0027] Figure 4 It is a structural schematic diagram of an oil channel support bar of a low-voltage double-layer winding structure according to an embodiment of the present invention;

[0028] Figure 5 for Figure 3 Front view after hiding the insulation barrel;

[0029] Figure 6 It is a structural schematic diagram of an insulating cylinder and an oil channel support bar of a low-voltage double-layer winding structure according to an embodiment of the present invention;

[0030] Figure 7 It is a schematic diagram of a low voltage double-layer winding structure according to an embodiment of the present invention;

[0031] Figure 8 This is a schematic diagram of the existing winding structure.

[0032] Among them: 1. Inner paper tube; 2. Inner winding; 3. Oil channel support bar; 31. Overlap groove; 4. Insulating tube; 5. Outer winding; 6. Heat dissipation oil channel; 61. Oil channel separation area; 7. Non-breakdown risk area; 8. Breakdown risk area; 3a. Inner support bar; 3b. Outer support bar; 4a. Insulating board. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0034] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B as an example", it includes solution A, or solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] The invention provides a low-voltage double-layer winding structure.

[0038] In the embodiment of the present invention, Figures 1 to 6As shown, the low-voltage double-layer winding structure is applied to a transformer, comprising an inner paper tube 1, an inner winding 2, a plurality of oil channel stays 3, an insulating tube 4 and an outer winding 5;

[0039] The inner winding 2 is arranged around the inner paper tube 1, the outer winding 5 is arranged on the side of the inner winding 2 away from the inner paper tube 1, and the side of the outer winding 5 close to the inner paper tube 1 is provided with an insulating tube 4, and a plurality of oil channel stays 3 are arranged between the inner winding 2 and the outer winding 5, and each oil channel stay 3 is extended along the axial direction of the inner paper tube 1 to form a heat dissipation oil channel 6 between the inner winding 2 and the outer winding 5;

[0040] Each oil channel support bar 3 has a lap groove 31 on one side facing away from the inner layer winding 2 along its thickness direction. The height of the insulating tube 4 matches the length of the lap groove 31. The insulating tube 4 is lapped on the lap grooves 31 of several oil channel support bars 3, and the groove wall of the oil channel support bar 3 corresponding to the lap groove 31 is in contact with the side of the insulating tube 4.

[0041] The inner winding 2 and the outer winding 5 both include a non-breakdown risk area 7 and a breakdown risk area 8 , and the overlapping grooves 31 are provided corresponding to the breakdown risk area 8 of the inner winding 2 and the breakdown risk area 8 of the outer winding 5 .

[0042] In the present low-voltage double-layer winding structure, the inner winding 2 and the outer winding 5 both include a non-breakdown risk area 7 and a breakdown risk area 8. According to the voltage gradient distribution characteristics of the layer winding, each oil channel support 3 is provided with a lap groove 31 along its own thickness direction on a side away from the inner winding 2. By correspondingly setting the lap groove 31 in the two breakdown risk areas 8, an oil channel support 3 and an insulating tube 4 are provided between the breakdown risk area 8 of the inner winding 2 and the breakdown risk area 8 of the outer winding 5. The insulating tube 4 is used to protect the two breakdown risk areas 8, effectively improving the insulation strength between the two and avoiding the occurrence of operating breakdown. Since the insulation strength between the non-breakdown risk area 7 of the inner winding 2 and the non-breakdown risk area 7 of the outer winding 5 has reached the requirements of the electrical safety standards and no operating breakdown will occur, no insulating tube 4 is provided between the two non-breakdown risk areas 7, and only the oil channel support 3 is provided. The overall insulation strength of the present low-voltage double-layer winding structure is high, meets the requirements of the electrical safety standards, and can operate safely.

[0043] In the present low-voltage double-layer winding structure, the oil channel support bar 3 is partially grooved, and the two breakdown risk areas 8 correspond to the overlapping grooves 31, while the oil channel support bars 3 corresponding to the two non-breakdown risk areas 7 are not grooved. Therefore, the oil channel support bars 3 corresponding to the two non-breakdown risk areas 7 have a larger thickness, which can further increase the thickness of the heat dissipation oil channel 6, improve the overall heat dissipation performance, and ensure that the heat dissipation requirements between the inner winding 2 and the outer winding 5 are met. Therefore, the present low-voltage double-layer winding structure can simultaneously meet the electrical safety standard requirements and the winding heat dissipation requirements.

[0044] In addition, the oil channel support bar 3 is partially grooved so that the overlapping groove 31 with a certain depth can be used to place the insulating tube 4, so that the insulating tube 4 does not occupy an extra layer of space, which effectively improves the space utilization rate. With this low-voltage double-layer winding structure, the coils can be arranged more closely during the layer winding, effectively reducing the radial size of the outer winding 5. This low-voltage double-layer winding structure has the characteristics of reasonable and compact overall structure, small space occupation and high short-circuit resistance. Moreover, reducing the radial size of the outer winding 5 can reduce the amount of coils used, reduce the consumption of raw materials, thereby reducing production costs and having better economic efficiency. Therefore, this low-voltage double-layer winding structure takes into account economic efficiency, electrical safety and heat dissipation performance at the same time.

[0045] In addition, in the existing winding structure, one layer of heat dissipation oil channel corresponds to one winding, that is, one layer of heat dissipation oil channel can only be used to achieve heat dissipation of one winding, while the low-voltage double-layer winding structure adopts a layer of heat dissipation oil channel 6 to achieve simultaneous heat dissipation of the inner winding 2 and the outer winding 5. Therefore, the low-voltage double-layer winding structure also has the advantage of high heat dissipation utilization rate.

[0046] The low-voltage double-layer winding structure solves the technical problems that the outer winding of the existing double-layer winding structure has an excessively large radial dimension, resulting in a large amount of coils and high production costs, and the overall winding structure occupies a large space, resulting in an increase in the size of the transformer.

[0047] In order to make the present invention more easily understood, Figure 7 and Figure 8 In the low voltage double layer winding structure of the present invention, Figure 7 As shown, the thickness of the oil channel support bar 3 is 6mm, the thickness of the overlap groove 31 is 1.5mm, and the thickness of the insulating tube 4 is also 1.5mm. At this time, the breakdown risk area 8 of the inner winding 2 and the breakdown risk area 8 of the outer winding 5 correspond to the 1.5mm insulating tube 4 and the 4.5mm oil channel support bar 3, and the non-breakdown risk area 7 of the inner winding 2 and the non-breakdown risk area 7 of the outer winding 5 correspond to the 6mm oil channel support bar 3, so the thickness of the heat dissipation oil channel 6 between the inner winding 2 and the outer winding 5 is 6mm. Figure 8As shown, in the existing winding structure, inner support bars 3a, outer support bars 3b and insulating plates 4a (equivalent to insulating tubes 4) are arranged between the inner winding 2 and the outer winding 5. Assuming that the thickness of the inner support bars 3a and the outer support bars 3b are both 5 mm, and the thickness of the insulating plates 4a is 1.5 mm, then the thickness between the inner winding 2 and the outer winding 5 is 11.5 mm, which is greater than the 6 mm thickness of the present invention. Therefore, the outer winding 5 of the existing winding structure has a large radial dimension, a large amount of coils, poor economy, poor coil winding compactness, and low short-circuit resistance. The present invention can reduce the radial dimension of the outer winding 5, reduce the amount of coils, have better economy, more compact coil winding, and high short-circuit resistance.

[0048] Further, the oil channel stay 3 corresponding to the non-breakdown risk area 7 of the inner winding 2 and the non-breakdown risk area 7 of the outer winding 5 is arranged between the inner winding 2 and the outer winding 5. At this time, the heat dissipation oil channel 6 corresponding to the non-breakdown risk area 7 of the inner winding 2 and the non-breakdown risk area 7 of the outer winding 5 is arranged between the inner winding 2 and the outer winding 5;

[0049] The oil channel support bar 3 corresponding to the breakdown risk zone 8 of the inner winding 2 and the breakdown risk zone 8 of the outer winding 5 is arranged between the inner winding 2 and the insulating tube 4. At this time, the heat dissipation oil channel 6 corresponding to the breakdown risk zone 8 of the inner winding 2 and the breakdown risk zone 8 of the outer winding 5 is arranged between the insulating tube 4 and the inner winding 2.

[0050] Further explanation: non-breakdown risk area 7 is an area where the operating voltage difference between two symmetrical points of the same width of the inner winding 2 and the outer winding 5 is less than 5 kV, and this area corresponds to the oil channel support bar 3. Breakdown risk area 8 is an area where the operating voltage difference between two symmetrical points of the same width of the inner winding 2 and the outer winding 5 is greater than or equal to 5 kV, and this area corresponds to the oil channel support bar 3 and the insulating cylinder 4. The inner winding 2 and the outer winding 5 are continuously wound with the same wire, and the winding directions of the inner winding 2 and the outer winding 5 are opposite.

[0051] To further illustrate, the low voltage double-layer winding structure is used in the voltage range of 3kV-35kV.

[0052] Preferably, the winding height of the inner winding 2 is the same as the winding height of the outer winding 5 .

[0053] like Figure 3 , 5 As shown in FIG. 6 , in one embodiment of the present application, the height of the insulating tube 4 is half of the height of the inner paper tube 1 , and the length of the oil channel support bar 3 is the same as the height of the inner paper tube 1 .

[0054] According to the gradient distribution characteristics of the line turn voltage in the layer winding along the axial direction of the winding, the height of the insulating tube 4 is set to half the height of the inner paper tube 1, so that the insulating tube 4 can be used to protect the two breakdown risk areas 8, improve the insulation strength, and ensure that the requirements of the electrical safety standards are met; the two non-breakdown risk areas 7 are only provided with oil channel struts 3, and at this time, half of the length of the oil channel struts 3 is not grooved, so this part of the oil channel struts 3 still has a relatively high thickness, thereby increasing the thickness of the heat dissipation oil channel 6 corresponding to the two non-breakdown risk areas 7 as much as possible, and improving the overall heat dissipation performance. Therefore, this low-voltage double-layer winding structure not only ensures that the winding heat dissipation requirements and electrical safety standards are met, but also simplifies the design of the low-voltage double-layer winding structure and the transformer using the low-voltage double-layer winding structure, reduces the design complexity, is conducive to standardized design, and also helps to improve production and assembly efficiency. When the length of the oil channel struts 3 is the same as the height of the inner paper tube 1, the mechanical strength of the low-voltage double-layer winding structure can be improved to prevent it from being deformed or damaged when subjected to external forces.

[0055] To further illustrate, the inner winding 2 and the outer winding 5 are arranged symmetrically to each other, as shown in FIG. Figure 7 As shown, the difference between the voltage at the middle point C of the inner winding 2 and the voltage at the middle point D of the outer winding 5 is half the difference between the voltage at point A of the inner winding 2 and the voltage at point X of the outer winding 5.

[0056] like Figure 7As shown, taking a 10kV corner-connected low-voltage winding as an example, the voltage at point A is 0kV, the voltage at point X is 10kV, the operating voltage difference between the two is 10kV, the voltage at point C in the middle of the inner winding 2 and the operating voltage difference at point D in the middle of the outer winding 5 is 5kV, and the operating voltage difference gradually decreases from left to right. At this time, the breakdown risk area 8 of the inner winding 2 is the AC area, and the breakdown risk area 8 of the outer winding 5 is the XD area. The oil channel support bar 3 and the insulating cylinder 4 are correspondingly arranged between the AC area and the XD area, that is, the part with high voltage difference is protected by a local insulating cylinder 4 to ensure insulation strength, and to take into account both economy and heat dissipation performance. The area with an operating voltage difference of less than 5kV is a non-breakdown risk area 7. At this time, the non-breakdown risk area 7 of the inner winding 2 is a CE area, and the non-breakdown risk area 7 of the outer winding 5 is a DF area. Only the oil channel support bar 3 is set between the CE area and the DF area. This is because the insulation strength of this part has reached the requirements of the electrical safety standards, and there is no need to use an insulating tube 4 for covering insulation. The oil channel support bars 3 corresponding to the two non-breakdown risk areas 7 have a relatively large thickness. In the part with low voltage difference, the thickness of the heat dissipation oil channel 6 is increased as much as possible to increase the heat dissipation surface and improve the heat dissipation performance. This low-voltage double-layer winding structure can cleverly utilize the different operating voltage differences of various parts during the operation of the winding, increase the heat dissipation surface as much as possible in the part with low voltage difference, and use local insulating tubes 4 for protection in the part with high voltage difference, which can take into account both economy and heat dissipation.

[0057] like Figure 1 and 5 As shown, in one embodiment of the present application, the thickness of a plurality of oil channel stays 3 is the same, and the oil channel stays 3 are evenly arranged along the circumference of the inner layer winding 2 .

[0058] A plurality of oil channel struts 3 are arranged uniformly along the circumference of the inner winding 2 and have the same thickness. An oil channel partition area 61 is formed between two adjacent oil channel struts 3. Each oil channel partition area 61 is uniform in size. A plurality of oil channel partition areas 61 together form a heat dissipation oil channel 6. The transformer oil flows uniformly, thereby effectively improving the heat dissipation efficiency. It can also ensure that the insulation distance between the inner winding 2 and the outer winding 5 is consistent, reducing the risk of electrical breakdown. In addition, it can also enhance the structural stability of the low-voltage double-layer winding structure.

[0059] Specifically, the cross-sectional shape of the oil channel stay 3 is a rectangle.

[0060] In one embodiment of the present application, the thickness of the oil channel support bar 3 is 4 mm-8 mm.

[0061] The oil channel support bar 3 with a thickness of 4mm-8mm can ensure that the heat dissipation requirements of the inner winding 2 and the outer winding 5 are met, so that the low-voltage double-layer winding structure has good heat dissipation performance, while reducing the electrical interference between the inner winding 2 and the outer winding 5, and can also ensure the overall mechanical strength of the low-voltage double-layer winding structure.

[0062] In one embodiment of the present application, the thickness of the oil channel support bar 3 is 6 mm.

[0063] When the thickness of the oil channel support bar 3 is 6 mm, a heat dissipation oil channel 6 with a suitable thickness can be formed between the inner winding 2 and the outer winding 5, which can effectively dissipate the heat of the inner winding 2 and the outer winding 5, so that the low-voltage double-layer winding structure has a higher heat dissipation performance, and also provide a stronger support force for the low-voltage double-layer winding structure to ensure the stability of the overall structure. By adopting a 6 mm thick oil channel support bar 3, the heat dissipation requirements of the inner winding 2 and the outer winding 5 can be met, ensuring the safe operation of the low-voltage double-layer winding structure. According to the different operating pressure differences of various parts when the inner winding 2 and the outer winding 5 are in operation, the area with low pressure difference (<5kV) is a non-breakdown risk area 7, and the two non-breakdown risk areas 7 are correspondingly provided with oil channel support bars 3. The thickness of the heat dissipation oil channel 6 is increased as much as possible in this area to improve the heat dissipation performance. The area with high voltage difference (≥5kV) is the breakdown risk area 8, which is protected by the insulating tube 4. The two breakdown risk areas 8 are provided with oil channel support bars 3 and insulating tubes 4 to improve the insulation strength and ensure that the requirements of electrical safety standards are met. Therefore, the low-voltage double-layer winding structure takes into account heat dissipation performance, electrical safety and cost, and can meet the electrical safety standards and winding heat dissipation requirements at the same time.

[0064] like Figure 2 and 3 As shown, in one embodiment of the present application, the depth of the overlapping groove 31 is greater than or equal to the thickness of the insulation tube 4 .

[0065] The depth of the overlapping groove 31 is greater than or equal to the thickness of the insulating tube 4, which can ensure that the insulating tube 4 can be completely overlapped with the overlapping groove 31, thereby ensuring that a good insulation effect can be achieved between the two breakdown risk areas 8 corresponding to the insulating tube 4, meeting the requirements of electrical safety standards.

[0066] In one embodiment of the present application, the thickness of the insulating tube 4 is 1.5 mm-2 mm.

[0067] The thickness of the insulating tube 4 is set to 1.5 mm-2 mm, which can ensure that the insulating tube 4 can provide necessary electrical isolation and enhance the overall insulation performance.

[0068] For example, in one embodiment of the present invention, the thickness of the insulating tube 4 is 1.5 mm, and the depth of the overlapping groove 31 is 1.5 mm. At this time, the thickness of the oil channel support bar 3 corresponding to the non-breakdown risk area 7 is 6 mm, and the thickness of the oil channel support bar 3 corresponding to the breakdown risk area 8 is 4.5 mm.

[0069] In one embodiment of the present application, the height of the inner paper tube 1 = the winding height of the inner winding 2 + the insulation height of the upper end of the inner winding 2 + the insulation height of the lower end of the inner winding 2; the insulation height of the upper end of the inner winding 2 is the distance between the upper end surface of the inner winding 2 and the upper end surface of the oil channel support bar 3; the insulation height of the lower end of the inner winding 2 is the distance between the lower end surface of the inner winding 2 and the lower end surface of the oil channel support bar 3;

[0070] Or, the height of the inner paper tube 1 = the winding height of the outer winding 5 + the insulation height of the upper end of the outer winding 5 + the insulation height of the lower end of the outer winding 5; the insulation height of the upper end of the outer winding 5 is the distance between the upper end surface of the outer winding 5 and the upper end surface of the oil channel support 3; the insulation height of the lower end of the outer winding 5 is the distance between the lower end surface of the outer winding 5 and the lower end surface of the oil channel support 3.

[0071] The inner paper tube 1 of suitable height can not only provide necessary support for the low-voltage double-layer winding structure, improve the overall structural strength, help maintain structural stability and enhance electrical isolation, but also improve the heat dissipation effect of the low-voltage double-layer winding structure.

[0072] In the present invention, the minimum limit of the end insulation height is set for different operating voltages:

[0073] At an operating voltage of 10 kV or less, the minimum limits of the insulation height of the upper end of the inner winding 2, the insulation height of the lower end of the inner winding 2, the insulation height of the upper end of the outer winding 5, and the insulation height of the lower end of the outer winding 5 are all 10 mm;

[0074] At an operating voltage of 20 kV, the minimum limits of the insulation height of the upper end of the inner winding 2, the insulation height of the lower end of the inner winding 2, the insulation height of the upper end of the outer winding 5, and the insulation height of the lower end of the outer winding 5 are all 15 mm;

[0075] At an operating voltage of 35 kV, the minimum limits of the insulation height of the upper end of the inner winding 2, the insulation height of the lower end of the inner winding 2, the insulation height of the upper end of the outer winding 5, and the insulation height of the lower end of the outer winding 5 are all 20 mm. It should be noted that these are only minimum standards, and the actual end insulation height can be flexibly designed according to specific circumstances and is not limited here.

[0076] The present invention provides a transformer, comprising any one of the above-mentioned low-voltage double-layer winding structures.

[0077] By using the low-voltage double-layer winding structure, the radial size of the outer winding 5 can be effectively reduced. The overall structure of the low-voltage double-layer winding structure is reasonable and compact, and the space occupied is small, so the size of the transformer can be effectively reduced, the production cost can be effectively reduced, and the economy is better. It solves the technical problem that the radial size of the outer winding 5 of the existing double-layer winding structure is too large, which leads to an increase in the size of the transformer.

[0078] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A low voltage double layer winding structure, applied to a transformer, characterized in that: It includes an inner paper tube, an inner winding, a plurality of oil channel stays, an insulating tube and an outer winding; The inner layer winding is arranged around the inner paper tube, the outer layer winding is arranged on the side of the inner layer winding away from the inner paper tube, the insulating tube is arranged on the side of the outer layer winding close to the inner paper tube, and a plurality of oil channel stays are arranged between the inner layer winding and the outer layer winding, and each of the oil channel stays is extended along the axial direction of the inner paper tube to form a heat dissipation oil channel between the inner layer winding and the outer layer winding; Each of the oil channel struts has a lap groove on one side away from the inner layer winding along its thickness direction, the height of the insulating tube is adapted to the length of the lap groove, the insulating tube is lapped on the lap grooves of a plurality of the oil channel struts, and the groove wall of the oil channel strut corresponding to the lap groove is in contact with the side surface of the insulating tube; The inner winding and the outer winding both include a non-breakdown risk area and a breakdown risk area, and the overlapping grooves are arranged corresponding to the breakdown risk area of ​​the inner winding and the breakdown risk area of ​​the outer winding.

2. The low voltage double-layer winding structure according to claim 1, characterized in that: The height of the insulating tube is half of the height of the inner paper tube, and the length of the oil channel support bar is the same as the height of the inner paper tube.

3. The low voltage double layer winding structure according to claim 2, characterized in that: The thickness of the plurality of oil channel stays is the same, and the oil channel stays are evenly arranged along the circumference of the inner layer winding.

4. The low voltage double-layer winding structure according to claim 3, characterized in that: The thickness of the oil channel support strip is 4mm-8mm.

5. The low voltage double layer winding structure according to claim 4, characterized in that: The thickness of the oil channel support strip is 6 mm.

6. The low voltage double layer winding structure according to claim 1, characterized in that: The depth of the overlapping groove is greater than or equal to the thickness of the insulating tube 4 .

7. The low voltage double layer winding structure according to claim 6, characterized in that: The thickness of the insulating tube is 1.5 mm-2 mm.

8. The low voltage double layer winding structure according to claim 7, characterized in that: The height of the inner paper tube = the winding height of the inner winding + the insulation height of the upper end of the inner winding + the insulation height of the lower end of the inner winding; the insulation height of the upper end of the inner winding is the distance between the upper end surface of the inner winding and the upper end surface of the oil channel support; the insulation height of the lower end of the inner winding is the distance between the lower end surface of the inner winding and the lower end surface of the oil channel support; Or, the height of the inner paper tube = the winding height of the outer winding + the insulation height of the upper end of the outer winding + the insulation height of the lower end of the outer winding; the insulation height of the upper end of the outer winding is the distance between the upper end surface of the outer winding and the upper end surface of the oil channel support; the insulation height of the lower end of the outer winding is the distance between the lower end surface of the outer winding and the lower end surface of the oil channel support.

9. A transformer, characterized in that: It comprises a low voltage double-layer winding structure as described in any one of claims 1 to 8.

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