Main insulation structure of 35kV-level oil-immersed transformer

Abstract

The main insulation structure of the 35kV-level oil-immersed transformer comprises an iron core, a low-voltage coil and a high-voltage coil are sequentially wound on the peripheral side of the iron core from inside to outside, and a first supporting strip, a first paperboard layer, a second supporting strip and a soft angle ring are filled in a main empty channel between the low-voltage coil and the high-voltage coil. The first supporting strip, the first paperboard layer and the second supporting strip sequentially wrap the peripheral side face of the low-voltage coil from inside to outside, the inner end of the soft angle ring is inserted, clamped and fastened in a gap between the first paperboard layer and the second supporting strip, and the outer ends, extending out of the two ports of the main empty channel, of the soft angle ring are bent and then laid on the upper end face and the lower end face of the high-voltage coil in the annular direction. The first supporting strip, the second supporting strip, the low-voltage coil, the high-voltage coil and the first paperboard layer form a plurality of longitudinal oil channels. On the premise of ensuring the insulating property, the radial width of the main empty channel is effectively reduced, so that the volume of an assembled transformer product is effectively reduced, the overall assembly is simple, the manufacturing cost is reduced, the occupied space during storage and use is saved, and the heat dissipation performance is good.

Description

TECHNICAL FIELD

[0001] The utility model belongs to transformer technical field, concretely relates to a kind of main insulation structure of 35kV grade oil-immersed transformer. BACKGROUND

[0002] Distribution transformer is one of important equipment in power supply and distribution system of industrial and mining enterprises and civil buildings, which reduces 10 (6) kV or 35kV network voltage to 230 / 400V bus voltage used by user. Oil-immersed transformer is one of distribution transformer, which has high reliability and stability, high efficiency and energy saving, superior insulation performance, strong short-circuit resistance, good heat conduction performance and other advantages, so oil-immersed transformer is widely used in power supply and distribution system.

[0003] Oil-immersed transformer with layer winding structure has the advantages of simple structure and convenient winding compared with oil-immersed transformer with pie winding structure, so oil-immersed transformer with layer winding structure is widely used in 35kV-1600kVA capacity range; In addition, many transformer companies have applied oil-immersed transformer with layer winding structure to higher capacity.

[0004] Transformer insulation examination items mainly include power frequency withstand voltage, induction withstand voltage and lightning impulse, wherein power frequency withstand voltage mainly examines main insulation, induction withstand voltage mainly examines longitudinal insulation, and lightning impulse examines main insulation and longitudinal insulation, so the main insulation structure inside transformer needs to withstand double examination of power frequency withstand voltage and lightning impulse. The main insulation structure of existing oil-immersed transformer with layer winding structure mainly refers to the insulation performance of main air gap structure between low-voltage coil and high-voltage coil wound outside the core. However, the insulation strength of main air gap structure between high-voltage coil and low-voltage coil in oil-immersed transformer with layer winding structure decreases with the decrease of radial width distance of main air gap, so the existing oil-immersed transformer with layer winding structure needs to consider the insulation performance of main air gap structure between high-voltage coil and low-voltage coil during design, that is, the radial width of main air gap structure between high-voltage coil and low-voltage coil is generally more than 15mm, which leads to large volume of assembled transformer finished product, high manufacturing cost, and large space occupied during storage or use. Therefore, the utility model provides a kind of main insulation structure of 35kV grade oil-immersed transformer, to solve the above technical problems. SUMMARY

[0005] The utility model discloses a 35kV level oil -immersed transformer's main insulation structure, fills the support strip one, paperboard layer one, the support strip two and the soft corner ring structure of a plurality of in the inside of main air channel compact and reasonable design, under the premise of guaranteeing insulation performance, effectively reduces the radial width of main air channel, thereby makes the volume of the assembly forming transformer product effectively reduces, and the overall assembly is simple, helps to reduce manufacturing cost, saves the occupation space of storage and use time, and the support strip located paperboard layer one inside and outside makes the main air channel inside form a plurality of annular interval distribution in the inside and outside of paperboard layer one longitudinal oil channel, ensures the smoothness when condensate liquid circulates in the inside of main air channel, thereby ensures the transformer of 35kV level oil -immersed transformer's main insulation structure of the utility model has good heat dissipation performance.

[0006] To realize above-mentioned purpose, the technical scheme of the utility model is to design a 35kV level oil -immersed transformer's main insulation structure, including the iron core, the low voltage coil and the high voltage coil are sequentially wound from inside to outside on the outer circumferential side of the iron core, the main air channel is equipped between the low voltage coil and the high voltage coil, the main air channel is filled with a plurality of support strip one, paperboard layer one, a plurality of support strip two and soft corner ring, a plurality of the support strip one, paperboard layer one, a plurality of support strip two are sequentially coated on the outer circumferential side of the low voltage coil from inside to outside, the soft corner ring inner end is inserted and clamped and is fixed in the gap between paperboard layer one and support strip two, and the soft corner ring extends the upper end portion of the upper end port of main air channel, and after the upper end portion is bent, the soft corner ring is annularly laid on the upper end face of the high voltage coil, and after the lower end portion extending the lower end port of main air channel is bent, the soft corner ring is annularly laid on the lower end face of the high voltage coil, the support strip one and the low voltage coil, paperboard layer one form a plurality of longitudinal oil channels located in the inside of paperboard layer one, and the support strip two and the high voltage coil, paperboard layer one form a plurality of longitudinal oil channels located in the outside of paperboard layer one.

[0007] The utility model discloses a 35kV level oil -immersed transformer's main insulation structure, fills the support strip one, paperboard layer one, the support strip two and the soft corner ring structure of a plurality of in the inside of main air channel compact and reasonable design, under the premise of guaranteeing insulation performance, effectively reduces the radial width of main air channel, thereby makes the volume of the assembly forming transformer product effectively reduces, and the overall assembly is simple, helps to reduce manufacturing cost, saves the occupation space of storage and use time, and the support strip located paperboard layer one inside and outside makes the main air channel inside form a plurality of annular interval distribution in the inside and outside of paperboard layer one longitudinal oil channel, ensures the smoothness when condensate liquid circulates in the inside of main air channel, thereby ensures the transformer of 35kV level oil -immersed transformer's main insulation structure of the utility model has good heat dissipation performance.

[0008] The preferred technical scheme is that the soft corner ring comprises two, one of which is located at the upper end of the main air channel, and the other is located at the lower end of the main air channel.

[0009] Further preferred technical scheme is that the upper and lower ends of the second support bar are respectively provided with a ring-shaped stepped groove facing the paperboard layer, and the inner end of the soft corner ring is inserted into the corresponding ring-shaped stepped groove of the second support bar. When the first support bar, the paperboard layer, the second support bar and the soft corner ring are attached and covered outside the core, the overall consistency is good, and the inner end of the soft corner ring is embedded in the corresponding ring-shaped stepped groove of the second support bar, thereby further helping to reduce the radial width of the main air channel.

[0010] Further preferred technical scheme is that the depth h of the inner end of the soft corner ring inserted into the gap between the paperboard layer and the second support bar is greater than 60mm. The firmness of the inner end of the soft corner ring when inserted and installed inside the main air channel is ensured, and the soft corner ring is effectively prevented from coming out of the gap between the paperboard layer and the second support bar.

[0011] Further preferred technical scheme is that the thickness d1 of the first support bar is 4.25mm, the thickness d2 of the paperboard layer is 3mm, the thickness d3 of the second support bar is 5.75mm, and the thickness of the soft corner ring and the radial depth of the ring-shaped stepped groove are both 1mm. The radial width of the main air channel between the high-voltage coil and the low-voltage coil is D=d1+d2+d3=4.25mm+3mm+5.75mm=13mm, which is smaller than the radial width of the main air channel in the traditional oil-immersed transformer with a layer winding structure, which is greater than 15mm. The radial width of the main air channel is greatly reduced, thereby effectively reducing the volume of the assembled transformer product, reducing the manufacturing cost, and reducing the occupied space during storage and use.

[0012] The preferred technical scheme is that the soft corner ring is integrally formed, the upper end of the soft corner ring is annularly arranged on the upper end surface of the high-voltage coil, the lower end of the soft corner ring is annularly arranged on the lower end surface of the high-voltage coil, the outer side surface of the soft corner ring is further covered with a second paperboard layer, and the second support bar forms a plurality of longitudinal oil channels with the high-voltage coil and the second paperboard layer. By using the soft corner ring with an integrated structure, the shortest path between the high-voltage side and the low-voltage side also passes through the edge of the corner ring, effectively increasing the creepage distance of the outgoing line between the high-voltage side and the low-voltage side, thereby significantly improving the insulation performance of the main insulation structure of the 35kV oil-immersed transformer.

[0013] Further preferred technical solutions also have, the thickness d1 of the strut one = 4.25 mm, the thickness d3 of the strut two = 4.25 mm, the thickness of the paperboard layer one, the soft angle ring and the paperboard layer two are all 1 mm, then the sum of the thickness of the paperboard layer one, the soft angle ring and the paperboard layer two d2 = 3 mm.The radial width of the main air channel between the high-voltage coil and the low-voltage coil is D = d1+d2+d3 = 4.25 mm + 3 mm + 4.25 mm = 11.5 mm, which is smaller than the radial width of the main air channel in the traditional layer type winding structure of the oil-immersed transformer, which is more than 15 mm, greatly reducing the radial width of the main air channel, thereby effectively reducing the volume of the assembled transformer product, reducing the manufacturing cost, and reducing the occupied space during storage and use.

[0014] Further preferred technical solutions also have, the upper and lower ends of the low-voltage coil are respectively provided with a low-voltage end insulation layer, the upper and lower ends of the high-voltage coil are sequentially provided with a high-voltage end insulation layer one and a high-voltage end insulation layer two from inside to outside, the outer end of the soft angle ring is laid on the outer side of the high-voltage end insulation layer two, and the outer side of the outer end of the soft angle ring is flush with the outer side of the low-voltage end insulation layer, and the outer side of the outer end of the soft angle ring and the outer side of the low-voltage end insulation layer are laid with an iron yoke insulation layer. Further strengthen the protection of the coil end insulation weak place, improve the coil end field intensity distribution, ensure that the high-voltage transformer has enough electrical strength to the low-voltage coil, to the iron core, to the ground, so as to ensure that the transformer can run safely for a long time.

[0015] Further preferred technical solutions also have, the low-voltage coil and the high-voltage coil are sequentially provided with a plurality of support bars three for heat dissipation, and the support bars three and the layers of the low-voltage coil or the high-voltage coil form a plurality of longitudinal oil channels. Ensure that the condensate can flow effectively in the gap between the layers of the high-voltage coil and the low-voltage coil, and in the gap between the layers of the high-voltage coil, thereby helping to improve the cooling efficiency of the condensate on the high-voltage coil and the low-voltage coil.

[0016] Further preferred technical solutions also have, the plurality of strut one, paperboard layer one, plurality of strut two and soft angle ring are all fixedly arranged on the outer circumferential side of the iron core. The fixing mode of each cladding layer on the outside of the iron core is simple and firm, which helps to improve the assembly and processing efficiency of the main insulation structure of the 35kV oil-immersed transformer, and prolong the service life of the transformer.

[0017] The advantages and beneficial effects of the present application are as follows:

[0018] 1. The main insulation structure of the 35kV oil-immersed transformer, the several supporting rods one, the paperboard layer one, the several supporting rods two and the soft corner ring structure filled in the main air channel are compact and reasonable in design, the radial width of the main air channel is effectively reduced under the premise of ensuring the insulation performance, so that the volume of the assembled transformer product is effectively reduced, the overall assembly is simple, which helps to reduce the manufacturing cost, save the occupied space during storage and use; the supporting rods located on the inner and outer sides of the paperboard layer one form several longitudinal oil channels which are distributed in the inner and outer sides of the paperboard layer one in a ring direction, so that the smoothness of the condensate circulating in the main air channel is ensured, and the transformer with the main insulation structure of the 35kV oil-immersed transformer of the utility model has good heat dissipation performance.

[0019] 2. The soft corner ring comprises two, one of the soft corner rings is located at the upper end of the main air channel, and the other soft corner ring is located at the lower end of the main air channel. The protection of the relatively weak insulation of the coil end part is strengthened, the field strength distribution of the coil end part is improved, the creepage distance of the coil end part is increased, the electrical strength of the high-voltage coil of the high-voltage transformer to the low-voltage coil, to the core and to the ground is sufficient, so that the long-term safe operation of the transformer is ensured.

[0020] 3. The upper and lower ends of the supporting rod two are respectively provided with a ring direction step groove facing the paperboard layer one, and the inner end of the soft corner ring is inserted into the corresponding ring direction step groove inside the supporting rod two. When the supporting rod one, the paperboard layer one, the supporting rod two and the soft corner ring are attached and coated outside the core, the overall consistency is good, the inner end of the soft corner ring is embedded in the corresponding ring direction step groove inside the supporting rod two, so as to further help to reduce the radial width size of the main air channel.

[0021] 4. The thickness of the supporting rod one is d1=4.25mm, the thickness of the paperboard layer one is d2=3mm, the thickness of the supporting rod two is d3=5.75mm, and the thickness of the soft corner ring and the radial depth of the ring direction step groove are both 1mm. The radial width of the main air channel between the high-voltage coil and the low-voltage coil is D=d1+d2+d3=4.25mm+3mm+5.75mm=13mm, which is smaller than the radial width of the main air channel in the traditional oil-immersed transformer with layer winding structure, which is more than 15mm, so that the volume of the assembled transformer product is effectively reduced, the manufacturing cost is reduced, and the occupied space during storage and use is reduced.

[0022] 5. The soft angle ring is clamped and fixed in the gap between the cardboard layer one and the support strip two. The upper end of the soft angle ring is circumferentially laid on the upper end face of the high-voltage coil, and the lower end of the soft angle ring is circumferentially laid on the lower end face of the high-voltage coil. The outer surface of the soft angle ring is also covered with the cardboard layer two. The support strip two, the high-voltage coil, and the cardboard layer two form several longitudinal oil channels. By adopting an integrated soft angle ring structure, the shortest path between the high-voltage side and the low-voltage side must pass through the edge of the angle ring, effectively increasing the creepage distance of the outgoing lines between the high-voltage side and the low-voltage side, thereby significantly improving the insulation performance of the main insulation structure of the 35kV oil-immersed transformer of this utility model.

[0023] 6. The thickness of the first support bar is d1 = 4.25mm, the thickness of the second support bar is d3 = 4.25mm, and the thickness of the first cardboard layer, the soft corner ring, and the second cardboard layer is 1mm. Therefore, the sum of the thicknesses of the first cardboard layer, the soft corner ring, and the second cardboard layer is d2 = 3mm. The radial width of the main channel between the high-voltage coil and the low-voltage coil is D = d1 + d2 + d3 = 4.25mm + 3mm + 4.25mm = 11.5mm. Compared with the radial width of the main channel in the traditional layered winding structure of oil-immersed transformers, which is more than 15mm, the radial width of the main channel is significantly reduced. This effectively reduces the size of the assembled transformer product, lowers manufacturing costs, and reduces the space occupied during storage and use. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the main insulation structure of a 35kV oil-immersed transformer in Example 1;

[0025] Figure 2 yes Figure 1 A magnified view of a section at point H in the middle;

[0026] Figure 3 This is a schematic diagram of the main insulation structure of a 35kV oil-immersed transformer in Example 2;

[0027] Figure 4 yes Figure 3 A magnified view of the area at point S in the middle.

[0028] In the diagram: 1. Iron core; 2. Low-voltage coil; 3. High-voltage coil; 4. Main air channel; 5. Support bar one; 6. Cardboard layer one; 7. Support bar two; 8. Soft corner ring; 9. Low-voltage end insulation layer; 10. High-voltage end insulation layer one; 11. High-voltage end insulation layer two; 12. Iron yoke insulation layer; 13. Cardboard layer two; 14. Longitudinal oil channel; 7-1. Circumferential stepped groove. Detailed Implementation

[0029] The specific embodiments of the utility model are further described below in combination with the drawings and examples. The following examples are only used to more clearly illustrate the technical scheme of the utility model, and cannot be used to limit the protection scope of the utility model.

[0030] Example 1

[0031] As Figures 1-2 shown, the utility model is a kind of main insulation structure of 35kV grade oil-immersed transformer, including core 1, the core 1 outer periphery side is successively wound with low voltage coil 2 and high voltage coil 3 from inside to outside, the low voltage coil 2 and high voltage coil 3 between being equipped with main air channel 4, the main air channel 4 inside is filled with several support bar one 5, paperboard layer one 6, several support bar two 7 and soft angle ring 8, several the support bar one 5, paperboard layer one 6, several support bar two 7 are successively coated on the outer periphery side surface of low voltage coil 2 from inside to outside, the inner end of the soft angle ring 8 is inserted and clamped and is fixed in the gap between paperboard layer one 6 and support bar two 7, and soft angle ring 8 extends the upper end of the upper end of main air channel 4 and is bent after loop laying on the upper end surface of high voltage coil 3, soft angle ring 8 extends the lower end of the lower end of main air channel 4 and is bent after loop laying on the lower end surface of high voltage coil 3, support bar one 5 and low voltage coil 2, paperboard layer one 6 form several longitudinal oil channels 14 located in the inside of paperboard layer one 6, support bar two 7 and high voltage coil 3, paperboard layer one 6 form several longitudinal oil channels 14 located in the outside of paperboard layer one 6.

[0032] Preferably, the soft angle ring 8 includes two, one the soft angle ring 8 is located in the upper end of main air channel 4, and the other soft angle ring 8 is located in the lower end of main air channel 4.

[0033] Further preferably, the upper and lower ends of the support bar two 7 are respectively provided with annular stepped groove 7-1 towards paperboard layer one 6, and the inner end of the soft angle ring 8 is inserted into the inner part of the corresponding annular stepped groove 7-1 of the support bar two 7.

[0034] Further preferably, the depth h of the inner end of the soft angle ring 8 inserted into the gap between paperboard layer one 6 and support bar two 7 is greater than 60mm.

[0035] Further preferably, the thickness d1 of the strut 5 is 4.25 mm, the thickness d2 of the paperboard layer 6 is 3 mm, the thickness d3 of the strut 7 is 5.75 mm, the thickness of the soft angle ring 8 and the radial depth of the annular stepped groove 7-1 are both 1 mm. The radial width of the main air channel between the high-voltage coil and the low-voltage coil is D = d1 + d2 + d3 = 4.25 mm + 3 mm + 5.75 mm = 13 mm, which is smaller than the radial width of the main air channel in the traditional layered winding structure of the oil-immersed transformer, which is more than 15 mm. The radial width of the main air channel is greatly reduced, thereby effectively reducing the volume of the assembled transformer product, reducing the manufacturing cost, and reducing the occupied space during storage and use.

[0036] Further preferably, the upper and lower end faces of the low-voltage coil 2 are respectively provided with a low-voltage end insulation layer 9, the upper and lower end faces of the high-voltage coil 3 are sequentially provided with a high-voltage end insulation layer one 10 and a high-voltage end insulation layer two 11 from inside to outside, the outer end of the soft angle ring 8 is laid on the outer side of the high-voltage end insulation layer two 11, and the outer side of the outer end of the soft angle ring 8 is flush with the outer side of the low-voltage end insulation layer 9, and the outer side of the outer end of the soft angle ring 8 and the outer side of the low-voltage end insulation layer 9 are laid with an iron yoke insulation layer 12.

[0037] Further preferably, the layers of the low-voltage coil 2 and the high-voltage coil 3 are annularly spaced apart by a plurality of struts three for heat dissipation, and the struts three and the layers of the low-voltage coil 2 or the high-voltage coil 3 form a plurality of longitudinal oil channels 14.

[0038] Further preferably, the plurality of struts one 5, the paperboard layer one 6, the plurality of struts two 7, and the soft angle ring 8 are all bound and coated and fixed on the outer circumferential side of the iron core 1.

[0039] The main insulation structure of the 35kV oil-immersed transformer of the utility model, the plurality of struts one, the paperboard layer one, the plurality of struts two and the soft angle ring structure filled in the main air channel are compact and reasonable in design, effectively reduce the radial width of the main air channel under the premise of guaranteeing the insulation performance, thereby effectively reducing the volume of the assembled transformer product, the overall assembly is simple, which helps to reduce the manufacturing cost and save the occupied space during storage and use; the struts on the inner and outer sides of the paperboard layer one make the main air channel form a plurality of longitudinal oil channels which are annularly spaced and distributed on the inner and outer sides of the paperboard layer one, thereby ensuring the smoothness of the condensate flowing in the main air channel, and ensuring that the transformer adopting the main insulation structure of the 35kV oil-immersed transformer of the utility model has good heat dissipation performance.

[0040] Example 2

[0041] As Figures 3-4As shown, the utility model relates to a kind of main insulation structure of 35kV grade oil-immersed transformer, and the difference between the main insulation structure of a kind of 35kV grade oil-immersed transformer in embodiment 1 is as follows: the soft angle ring 8 middle part is penetrated and clamped and is arranged in the gap between paperboard layer one 6 and support bar two 7, the upper end of soft angle ring 8 is annularly laid on the upper end surface of high voltage coil 3, the lower end of soft angle ring 8 is annularly laid on the lower end surface of high voltage coil 3, paperboard layer two 13 is further coated on the outer side of soft angle ring 8, and support bar two 7, high voltage coil 3 and paperboard layer two 13 form several longitudinal oil channels 14.Concretely, paperboard layer two 13 is bound and coated and fixed on the outer circumferential side of soft angle ring 8.By using the soft angle ring of integrated structure, the shortest path between high voltage side and low voltage side also passes through the edge of angle ring, effectively increases the creepage distance of outgoing line between high voltage side and low voltage side, so as to significantly improve the insulation performance of the main insulation structure of 35kV grade oil-immersed transformer of the utility model.

[0042] Preferably, the thickness d1 of support bar one 5 is 4.25mm, the thickness d3 of support bar two 7 is 4.25mm, the thickness of paperboard layer one 6, soft angle ring 8 and paperboard layer two 13 is all 1mm, and the sum d2 of the thickness of paperboard layer one 6, soft angle ring 8 and paperboard layer two 13 is 3mm.The radial width of main air channel between high voltage coil and low voltage coil is D=d1+d2+d3=4.25mm+3mm+4.25mm=11.5mm, which is smaller than the radial width of main air channel in traditional layer winding structure oil-immersed transformer, which is more than 15mm, so that the radial width of main air channel is greatly reduced, so that the volume of assembled transformer product is effectively reduced, the manufacturing cost is reduced, and the occupied space during storage and use is reduced.

[0043] The main insulation structure of 35kV grade oil-immersed transformer of the utility model is not limited to 35kV grade oil-immersed transformer, and is also applicable to oil-immersed transformers of other voltage grades (such as 15kV, 20kV, 60kV grade).

[0044] The above is only the preferred embodiment of the utility model, and it should be pointed out that, for ordinary skilled person in the art, without departing from the technical principle of the utility model, a number of improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the utility model.

Claims

1. A main insulation structure of a 35 kV class oil-immersed transformer, comprising a core (1), said core (1) having a low-voltage coil (2) and a high-voltage coil (3) wound successively from the inside to the outside on the outer periphery side, said low-voltage coil (2) and said high-voltage coil (3) being provided with a main air gap (4) therebetween, characterized in that, The main cavity (4) is filled with a plurality of support bars (5), a paperboard layer (6), a plurality of support bars (7) and a soft corner ring (8). The plurality of support bars (5), the paperboard layer (6) and the plurality of support bars (7) are sequentially wrapped on the outer circumferential side of the low-voltage coil (2) from inside to outside. The inner end of the soft corner ring (8) is inserted into the gap between the paperboard layer (6) and the support bars (7), and the upper end of the soft corner ring (8) extending out of the upper end of the main cavity (4) is bent and annularly laid on the upper end surface of the high-voltage coil (3). The lower end of the soft corner ring (8) extending out of the lower end of the main cavity (4) is bent and annularly laid on the lower end surface of the high-voltage coil (3). The support bars (5), the low-voltage coil (2) and the paperboard layer (6) form a plurality of longitudinal oil channels (14) inside the paperboard layer (6). The support bars (7), the high-voltage coil (3) and the paperboard layer (6) form a plurality of longitudinal oil channels (14) outside the paperboard layer (6).

2. The main insulation structure of a 35 kV class oil-immersed transformer according to claim 1, characterized by, The soft corner ring (8) includes two, one of which is located at the upper end of the main cavity (4), and the other is located at the lower end of the main cavity (4).

3. The main insulation structure of a 35 kV class oil-immersed transformer according to claim 2, characterized by The upper and lower ends of the support bars (7) are respectively provided with annular stepped grooves (7-1) facing the paperboard layer (6). The inner end of the soft corner ring (8) is inserted into the corresponding annular stepped groove (7-1) inside the support bars (7).

4. The main insulation structure of a 35 kV class oil-immersed transformer according to claim 3, characterized by The depth h of the inner end of the soft corner ring (8) inserted into the gap between the paperboard layer (6) and the support bars (7) is greater than 60mm.

5. The main insulation structure of a 35 kV class oil-immersed transformer according to claim 4, characterized by The thickness d1 of the support bars (5) is 4.25mm, the thickness d2 of the paperboard layer (6) is 3mm, and the thickness d3 of the support bars (7) is 5.75mm. The thickness of the soft corner ring (8) and the radial depth of the annular stepped groove (7-1) are both 1mm.

6. The main insulation structure of a 35 kV class oil immersed transformer according to claim 1, wherein, The middle part of the soft corner ring (8) is inserted into the gap between the paperboard layer (6) and the support bars (7). The upper end of the soft corner ring (8) is annularly laid on the upper end surface of the high-voltage coil (3), and the lower end of the soft corner ring (8) is annularly laid on the lower end surface of the high-voltage coil (3). The outer side of the soft corner ring (8) is also wrapped with a paperboard layer (13). The support bars (7), the high-voltage coil (3) and the paperboard layer (13) form a plurality of longitudinal oil channels (14).

7. The main insulation structure of a 35 kV class oil-immersed transformer according to claim 6, characterized by The thickness d1 of the support bars (5) is 4.25mm, the thickness d3 of the support bars (7) is 4.25mm, and the thickness of the paperboard layer (6), the soft corner ring (8) and the paperboard layer (13) is 1mm. The sum of the thicknesses of the paperboard layer (6), the soft corner ring (8) and the paperboard layer (13) is d2=3mm.

8. The main insulation structure of a 35 kV class oil immersed transformer according to claim 1, wherein, The upper and lower end surfaces of the low-voltage coil (2) are respectively provided with low-voltage end insulation layers (9), the upper and lower end surfaces of the high-voltage coil (3) are sequentially provided with high-voltage end insulation layer one (10) and high-voltage end insulation layer two (11) from inside to outside, the outer end part of the soft corner ring (8) is laid on the outer side surface of the high-voltage end insulation layer two (11), and the outer side surface of the outer end part of the soft corner ring (8) is flush with the outer side surface of the low-voltage end insulation layer (9), and the outer side surface of the outer end part of the soft corner ring (8) and the outer side surface of the low-voltage end insulation layer (9) are laid with an iron yoke insulation layer (12).

9. The main insulation structure of a 35 kV class oil immersed transformer according to claim 1, wherein, The layers of the low-voltage coil (2) and the high-voltage coil (3) are annularly spaced with a plurality of supporting strips three for heat dissipation, and the supporting strips three and the layers of the low-voltage coil (2) or the high-voltage coil (3) form a plurality of longitudinal oil channels (14).

10. The main insulation structure of a 35 kV class oil-immersed transformer according to any one of claims 1 to 9, characterized by, The plurality of supporting strips one (5), paperboard layers one (6), a plurality of supporting strips two (7) and soft corner rings (8) are all fixedly arranged on the outer circumferential side surface of the iron core (1) by binding and covering.

Images