CN107705961B - vegetable oil power transformer - Google Patents

Abstract

The invention provides a vegetable oil power transformer. The vegetable oil power transformer. The invention provides a vegetable oil power transformer, comprising: the oil tank, the cake-type coil and the iron core are arranged in the oil tank, and vegetable oil is filled in the oil tank; the cake-type coil is provided with a plurality of layers of transverse oil ducts for the circulation of vegetable oil; the height of the middle oil duct arranged in the middle is a first size value, and the heights of the rest oil ducts are fifth size values; the first size value is greater than the fifth size value, and the second size value, the third size value, and the fourth size value are all less than the first size value and greater than or equal to the fifth size value. According to the vegetable oil power transformer, the oil passage through which vegetable oil flows is specially designed, the heights of the middle oil passage, the end oil passage, the first oil passage and the second oil passage are increased, the problem of high viscosity of vegetable oil is solved, the vegetable oil can flow more conveniently, the overall heat dissipation effect of the transformer is ensured, and the overload capacity of the transformer is improved.

Description

vegetable oil power transformer

Technical field

The present invention relates to the technical field of electric power equipment, and specifically to a vegetable oil electric power transformer.

Background technique

At present, because rural areas are under light load for most of the year, the utilization rate of transformers is very low; but during the Spring Festival and rural irrigation and harvest periods, rural electricity consumption may become several times that of before, and large-scale power consumption in rural areas Most transformers are seriously overloaded in a short period of time. This situation can easily lead to an increase in the operating temperature of the transformer, causing the transformer to burn out and cause a power outage. The lives of residents and the production of enterprises will also be affected to a certain extent.

At present, conventional 35kV power transformers generally use mineral insulating oil, which is an insulating oil obtained by fractionation and refining of petroleum. It is cheap and has good electrical properties. In order to reduce the oil pressure in the transformer while ensuring its cooling effect, existing transformers The height of each layer of oil passages installed inside is designed to be 3mm; however, due to the low heat resistance level of mineral insulating oil, when the load of the power transformer increases, or even overload operation, accidents may easily occur.

Vegetable insulating oil, as a high-ignition point oil, has been studied in Japan, Europe and the United States. Currently, a variety of vegetable insulating oils are on the market. These oils not only have good electrical properties, but are also fire-resistant and high-temperature resistant. They are easily degraded in nature and are more suitable for the future. Transformer process requirements and ecological needs. However, after using vegetable insulating oil as the transformer insulating fluid, due to its high kinematic viscosity and weaker cooling performance than mineral oil transformers, it is easy to cause the temperature of the hottest spot in some areas of the transformer's internal winding to be too high.

Contents of the invention

In view of this, the present invention proposes a vegetable oil power transformer, aiming to solve the problem of excessive temperature in the existing vegetable oil transformer.

The invention proposes a vegetable oil power transformer. The transformer includes: an oil tank, a cake-type coil and an iron core arranged in the oil tank. The oil tank is filled with vegetable oil for insulating and cooling the cake-type coil; the cake-type coil is filled with vegetable oil. There are several layers of transverse oil passages in the coil for the vegetable oil to circulate, which are arranged at an angle with the axis of the iron core; the height of the middle oil passage set in the middle is the first size value, and the two sides of the middle oil passage are The height of several first oil passages on the side is the second size value, and the height of several end oil passages arranged at both ends is the third size value; the heights above and closest to the first oil passages in the uppermost layer are In the second oil passage, the heights of the third oil passages below and closest to the first oil passage in the lowermost layer are all the fourth size value; the heights of the remaining oil passages are the fifth size value; the heights of the third oil passages are the fifth size value; One dimension value is greater than the fifth dimension value, and the second dimension value, the third dimension value and the fourth dimension value are all smaller than the first dimension value and greater than or equal to the fifth dimension value.

Further, in the above-mentioned vegetable oil power transformer, the fourth dimension value is less than or equal to the second dimension value.

Further, in the above-mentioned vegetable oil power transformer, the third dimension value is equal to the fourth dimension value.

Further, in the above-mentioned vegetable oil power transformer, the cake-type coil includes: a low-voltage coil and a high-voltage coil that are sleeved outside the iron core in sequence; wherein gaps are provided in the low-voltage coil and the high-voltage coil in one-to-one correspondence. , the corresponding gaps are connected to form the transverse oil passage for the vegetable oil to circulate.

Further, in the above-mentioned vegetable oil power transformer, the height of the part of the intermediate oil passage provided in the low-voltage coil is smaller than the height of the part provided in the high-voltage coil; the first oil passage is provided in the low-voltage coil. The height of the part is greater than the height of the part disposed inside the high-voltage coil.

Further, in the above-mentioned vegetable oil power transformer, a preset distance is provided between the top of the iron core and the top of the oil tank.

Furthermore, in the above-mentioned vegetable oil power transformer, the stays and/or pads provided on the upper part of the oil passage are made of high-temperature resistant insulating materials.

Further, in the above-mentioned vegetable oil power transformer, an oil temperature measuring structure is provided on the top of the oil tank for measuring the temperature on the top of the oil tank through an oil temperature measuring device.

Further, in the above-mentioned vegetable oil power transformer, the insulating paper covering the outer wall of the lead wire of the transformer is high-temperature resistant insulating paper.

In the vegetable oil power transformer provided by the present invention, the vegetable oil circulating in the oil tank has higher ignition point and flash point and stronger heat resistance than the mineral insulating oil used in the prior art, so as to further improve its cooling and insulation effects, and further Improve the overload capacity of the transformer and at the same time improve the fire protection performance of the transformer; through special design of oil channels that circulate vegetable oil, the height of the middle oil channel, end oil channel, first oil channel and second oil channel The enlarged size design is carried out to increase the height of the relevant oil channels, thereby overcoming the problem of high viscosity of vegetable oil and making the circulation of vegetable oil more convenient, thereby ensuring the overall heat dissipation effect of the transformer, improving the overload capacity of the transformer, and further expanding the The area where the transformer is used.

In particular, the vegetable oil power transformer provided by the present invention ensures that the height of the middle oil passage is designed to be increased through the design of the first dimension value being greater than the fifth dimension value, so as to improve the circulation of vegetable oil in the middle oil passage with poor heat dissipation effect. This further improves the heat dissipation effect of the middle oil passage, thereby avoiding excessive oil temperature and further improving the overload capacity of the transformer.

Further, in the vegetable oil power transformer provided by the present invention, the second size value, the third size value and the fourth size value are all smaller than the first size value and greater than or equal to the fifth size value, thereby minimizing the number of transformers. Under the condition of high coil height, the overall heat dissipation effect of the transformer is ensured, thereby further preventing the oil temperature in the transformer from overheating.

Description of the drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be construed as limiting the invention. Also throughout the drawings, the same reference characters are used to designate the same components. In the attached picture:

Figure 1 is a schematic structural diagram of a vegetable oil power transformer provided by an embodiment of the present invention;

Figure 2 is a top view of a pie coil provided by an embodiment of the present invention;

Figure 3 is a schematic structural diagram of a high-voltage coil provided by an embodiment of the present invention;

Figure 4 is a schematic structural diagram of a low-voltage coil provided by an embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a thorough understanding of the disclosure, and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

Refer to Figure 1, which is a schematic structural diagram of a vegetable oil power transformer provided by an embodiment of the present invention. The transformer includes: a fuel tank 1, a cake-type coil 2 and an iron core 3; wherein, the cake-type coil 2 and the iron core 3 are both arranged in the oil tank 1 Inside, the oil tank 1 is filled with vegetable oil for insulating and cooling the cake-type coil 2. There are several layers of transverse oil passages (not shown in the figure) for the circulation of vegetable oil in the cake-type coil 2, which are connected with the axis of the iron core 3 ( (vertical direction as shown in Figure 1) is set at an angle.

Specifically, it is well known to those skilled in the art that the oil tank 1 is provided with a holding chamber for holding insulating oil. The insulating oil is vegetable oil. According to the comparison between vegetable oil and mineral oil in Table 1, the fire point and flash point of vegetable oil are high. Its heat resistance is stronger in order to further improve its cooling and insulation effect, thereby improving the overload capacity of the transformer; in order to further improve its heat resistance, the vegetable oil is soybean oil; the iron core 3 is arranged in the oil tank 1 to form The magnetic circuit part of the transformer realizes the transmission and conversion of electromagnetic energy; in order to reduce the impact of high-temperature operation on the components and sealing materials on the top of the fuel tank 1, the fuel tank 1 adopts an enlarged design, and the top of the iron core 3 is between the top of the fuel tank 1 and the top of the fuel tank 1. The preset distance L1 between the intervals, that is, the distance between the top of the upper iron yoke 31 and the top of the fuel tank 1 is greater than the corresponding distance of the existing mineral insulating oil, so as to avoid excessive oil temperature causing damage to the components installed on the top of the fuel tank 1 Excessive temperature affects its operating effect; the iron core 3 includes a core column, an upper iron yoke 31 and a lower iron yoke 32. The core column is made of several silicon steel sheets stacked in sequence. The cake-type coil 2 is wound around the core of the iron core 3. on the column to realize the transformation of electromagnetic energy; the upper iron yoke 31 and the lower iron yoke 32 are respectively arranged above and below the core column to form a closed magnetic circuit to transmit electromagnetic energy; the pie coil 2 has a pie winding structure. It is composed of several coil cakes stacked in sequence; a reserved gap is provided between any two adjacent coil cakes to form a transverse oil passage for the circulation of vegetable oil, so the transverse oil passage is set at an angle with the axis of the iron core 3 ; In order to reduce the height of the transformer, it is preferable that the transverse oil passage is set horizontally, that is, the transverse oil passage is set vertically to the axis of the iron core 3, thereby reducing the oil pressure of the vegetable oil in the tank, thereby reducing the usage of vegetable oil in the tank.

It is well known to those in the art that the pie coil 2 of the transformer is connected to the external circuit through the lead 4; in order to prevent the oil temperature from being too high and affecting the use of the lead 4, it is preferred that the lead 4 is made of soft copper wire, and the lead 4 is connected to the cake. The connecting part of the type coil is welded with high-frequency welding process to ensure no burrs and ensure the quality of the weld, which can reduce the risk factor of transformer operation; in order to further ensure the normal operation of lead 4, the outer cover of lead 4 is equipped with a sleeve; in order to improve its heat resistance degree, the insulation paper covering the outer wall of lead 4 is high-temperature resistant insulation paper; in order to prevent the oil temperature in the oil tank 1 from being too high, an oil temperature measuring structure is provided on the top of the oil tank 1 for measuring the top of the oil tank 1 through an oil temperature measuring device The oil temperature in the oil tank 1 can be measured by setting a sensor at the oil temperature measuring structure, thereby facilitating the control of the oil temperature in the oil tank 1; in order to avoid being unable to replenish the oil in time when the oil tank 1 is in a state of oil shortage, the oil tank 1 is set There is an oil storage tank for storing and replenishing oil in the oil tank 1, so as to handle it in time when the oil tank 1 is short of oil or has too much oil; in order to avoid excessive pressure in the oil tank 1, the oil tank 1 is provided with a pressure release valve; in order to avoid excessive pressure in the oil tank 1; To prevent the vegetable oil from flowing out, preferably, a pressure relief valve is provided on the top of the oil tank 1 .

Table 1 Comparison of main performance parameters of vegetable oil and mineral insulating oil

Continuing to refer to Figure 1, there are several stay bars and/or spacers provided in the oil passage for supporting the oil passage clearance.

Specifically, the coil cakes are connected through braces and/or pads so that each coil cake is elevated, thereby providing an oil flow channel for the insulating medium of the transformer, that is, vegetable oil, to circulate and dissipate heat; because the oil channel is provided in the upper oil channel The temperature of vegetable oil is higher than the temperature in the lower oil passage, so the stays and/or pads set in the upper part of the oil passage are made of high-temperature-resistant insulating materials, while the stays and/or pads set in the lower part of the oil passage are made of conventional insulating materials. That is, in order to prevent the vegetable oil temperature in the upper part of the cake coil 2 from being too high and affecting the operation of the cake coil 2.

The height of the middle oil passage arranged in the middle is the first dimension value, the height of several first oil passages on both sides of the middle oil passage is the second dimension value, and the height of several end oil passages arranged at both ends is the third dimension value. Size values, the heights of several second oil channels above and closest to the first oil channel in the uppermost layer and several third oil channels below and closest to the first oil channel in the lowermost layer are all fourth size values, and the remaining The height of the oil passage is a fifth size value, wherein the first size value is greater than the fifth size value, and one or more of the second size value, the third size value and the fourth size value is less than the first size value and greater than or equal to Fifth size value.

Specifically, it is well known to those skilled in the art that the height of each oil passage in an existing transformer using mineral insulating oil is 3 mm; in order to prevent the height of the transformer using vegetable oil from being too high, preferably, the fifth dimension value is 3mm in order to avoid excessive oil pressure in the transformer and thereby prevent the waste of vegetable oil; and the vegetable insulating oil used in the present invention has a high kinematic viscosity, in order to ensure its fluidity in the transformer to meet the heat dissipation requirements of the transformer, It is necessary to relatively increase the size of the oil flow channel, and the oil channel in the transformer must be specially designed; since the vegetable oil in the middle oil channel has the worst heat dissipation effect, the first size value is larger than the fifth size value, and the second size value and the fourth size value are The size value is greater than or equal to the fifth size value in order to expand the height of the oil channel, thereby promoting the flow of vegetable oil, thereby preventing the oil temperature in the transformer from being too high; in order to prevent the temperature of the vegetable oil flowing in the end oil channel from being too high, causing the adjacent end The components of the oil passage are aging in order to increase the third dimension value, so the third dimension value is greater than the fifth dimension value. In order to avoid the height of the transformer being too high, the second dimension value, the third dimension value and the fourth dimension value are all smaller than the first dimension value and greater than or equal to the fifth dimension value.

It is obvious that in the vegetable oil power transformer provided in this embodiment, the vegetable oil circulating in the oil tank has higher ignition point and flash point and stronger heat resistance than the mineral insulating oil used in the prior art, so as to further improve Its cooling and insulation effects further improve the overload capacity of the transformer and at the same time improve the fire protection performance of the transformer; through special design of oil passages where vegetable oil circulates, the middle oil passage, end oil passage, and first oil passage are The height of the oil channel and the second oil channel is designed to increase the height of the relevant oil channel, thereby overcoming the problem of high viscosity of vegetable oil and making the circulation of vegetable oil more convenient, thereby ensuring the overall heat dissipation effect of the transformer and improving the efficiency of the transformer. The overload capacity of the transformer further expands the use area of the transformer.

In particular, the vegetable oil power transformer provided in this embodiment ensures that the height of the middle oil passage is designed to be increased through a design in which the first dimension value is greater than the fifth dimension value, so as to improve the circulation of vegetable oil in the middle oil passage with poor heat dissipation effect. , thereby improving the heat dissipation effect of the middle oil passage, thereby avoiding the phenomenon of excessive oil temperature, and further improving the overload capacity of the transformer.

Further, in the vegetable oil power transformer provided in this embodiment, the second size value, the third size value and the fourth size value are all smaller than the first size value and greater than or equal to the fifth size value, thereby minimizing the height of the transformer coil. Under these conditions, the overall heat dissipation effect of the transformer is ensured, thereby further avoiding overheating of the oil temperature in the transformer.

In order to facilitate processing and heat dissipation of the transformer, preferably, the fourth dimension value is less than or equal to the second dimension value.

Specifically, the thickness dimensions of the first oil passage, the second oil passage, the third oil passage and other oil passages extending from the middle oil passage to both sides can be reduced in order to increase the vegetable oil flowing in the middle oil passage. The heat dissipation effect, thereby overall improving the heat dissipation effect and overload capacity of the transformer; in order to further reduce the height of the transformer, preferably, the third size value is equal to the fourth size value, which not only ensures an increase in the thickness of the end oil passage , while reducing the height of the transformer to avoid wasting its vegetable oil.

It is obviously understandable that in this embodiment, the thickness of the third oil passage is smaller than the thickness of the second oil passage, in order to improve the heat dissipation effect of the oil passage arranged in the middle position and to prevent the transformer from being too high, thereby improving the overall heat dissipation of the transformer. effect and overload capacity, while avoiding the waste of vegetable oil in the transformer.

Referring to Figures 2 to 4, the pie-type coil 2 includes: a low-voltage coil 21 and a high-voltage coil 22 that are sleeved outside the iron core 3 in sequence; wherein, gaps are provided in the low-voltage coil 21 and the high-voltage coil 22 in correspondence with each other. The gaps are connected to form a transverse oil passage for vegetable oil to circulate.

Specifically, both the low-voltage coil 21 and the high-voltage coil 22 have a pie-type winding structure; the low-voltage coil 21 and the high-voltage coil 22 are respectively composed of several corresponding low-voltage coil cakes 211 and high-voltage coil cakes 221 stacked in sequence; any two A low-voltage gap 212 is provided between adjacent low-voltage coil cakes 211 along the axis of the iron core 3. A high-voltage gap 222 is provided between any two adjacent high-voltage coil cakes 221. The low-voltage gap 212 and the high-voltage gap 222 are connected. , in order to form a transverse oil passage for vegetable oil to circulate; according to the operation conditions of the low-voltage coil 21 and the high-voltage coil 22, preferably, the height of the part of the intermediate oil passage arranged in the low-voltage coil 21 is smaller than the height of the part arranged in the high-voltage coil 22 , that is to say, the height L211 of the middle low-voltage gap set at the most middle position is smaller than the height L221 of the middle high-voltage gap set at the most middle position, that is, L211<L221, so that the temperatures of the vegetable oil in the low-voltage coil 21 and the high-voltage coil 22 are more balanced. To avoid local overheating of the cake-type coil 2; the height of the part of the first oil passage arranged in the low-voltage coil 21 is greater than the height of the part arranged in the high-voltage coil 22. That is to say, the middle low-pressure gap arranged in the middle position is both upper and lower. The height L212 of the several first low-pressure gaps on the side is greater than the height L222 of the several first high-pressure gaps on both sides of the middle high-pressure gap located at the middle position, that is, L212>L222.

It is obviously understandable that the pie coil 2 provided in this embodiment improves the use range of the transformer through the arrangement of the low-voltage coil 21 and the high-voltage coil 22 so as to increase the range of voltage change to meet actual needs.

The vegetable oil power transformer provided by the embodiment of the present invention is described in more detail below:

As shown in Figures 1 to 4, the device includes: oil tank 1, pie coil 2 and iron core 3; which houses the transformer body and transformer insulation medium. At the same time, the oil tank is equipped with a top oil temperature measurement hole to facilitate measurement during operation. The temperature of the oil top layer is also equipped with a pressure relief valve and an oil conservator. There are lifting rings at the four corners of the top of the oil tank to facilitate lifting; in order to reduce the impact of high-temperature operation on the components and sealing materials on the top of the oil tank, the oil tank adopts an enlarged design, and its tank cover is The distance between the top of the transformer body is set to 30cm; the oil tank 1 is filled with transformer insulating medium. In order to improve the heat resistance of the transformer, the transformer insulating medium in this embodiment uses soybean-based plant insulating oil. Its ignition point is as high as 360°C while maintaining a relatively high temperature. Good insulation performance; the pie-type coil 2 includes a high-voltage coil 22 and a low-voltage coil 21, both of which are wound with copper wires. The winding type is pie-type continuous winding. The high-voltage coil voltage is 35kV, the low-voltage coil voltage is 400V, and the high-voltage coil 22 passes The high-voltage bushing is connected to the 35kV transmission line, and the low-voltage coil 21 is connected to the 400V transmission line through the low-voltage bushing. Due to the increased kinematic viscosity of vegetable insulating oil, when designing and manufacturing the transformer coils, a special design was adopted for some oil passages: both the high-voltage coil 22 and the low-voltage coil 21 have corresponding 46-cake coil cakes stacked from bottom to top. Arranged according to serial numbers 1-46; each line cake is supported by spacers to provide an oil flow channel for the circulation and heat dissipation of the transformer insulation medium. Each cake coil is provided with 12 spacers at 30° intervals; among them, the high-voltage coil 22 is in the middle The oil passage (between the 22nd and 23rd cakes) is designed to be 10mm, and the upper and lower oil passages in the middle are designed to be 4mm (between the 20th, 21st, and 22nd cakes and between the 23rd, 24th, and 25th cakes), and the high-voltage coil 22 The oil passages of the first four cakes at the head end and tail end are designed to be 4mm (between the 1st, 2nd, 3rd and 4th cakes and between the 43rd, 44th, 45th and 46th cakes), and the other oil channels are designed to be 3mm; among them , the oil passage gap in the high-voltage coil 22 is supported by a combination of pads. The 3mm oil passage is supported by a combination of two pads with a height of 1.5mm, a width of 40mm, and a length of 74.5mm. The 4mm oil passage is supported by a combination of two pads with a height of 2mm, a width of 40mm, and a length of 74.5mm. The 10mm oil channel is supported by a combination of pads with a length of 74.5mm. The 10mm oil passage is supported by a combination of five pads with a height of 2mm, a width of 40mm, and a length of 74.5mm. The pads in the coils between the 22nd and 46th cakes are all made of high heat-resistant grade materials. The pads between the 1st and 22nd cakes are made of conventional insulating materials; the middle oil passage of the low-voltage coil 21 (between the 22nd and 23rd cakes) is designed to be 8mm, and the upper and lower oil passages in the middle are designed to be 5mm (the 20th and 21st , 22nd cake and between 23rd, 24th and 25th cake), and the upper and lower three oil passages are designed to be 4mm (between 17th, 18th, 19th and 20th cake and between 25th, 26th, 27th and 28th cake) ) The oil channels of the first four cakes at the head end and tail end of the low-voltage coil 21 are designed to be 4mm (between the 1st, 2nd, 3rd cake and the 44th, 45th, and 46th cake), and the other oil channels are designed to be 3mm; the design of the spacer : The 3mm oil passage is supported by a combination of two pads with a height of 1.5mm, a width of 30mm, and a length of 48.5mm. The 4mm oil passage is supported by a combination of two pads with a height of 2mm, a width of 30mm, and a length of 48.5mm. The 5mm oil passage is supported by a combination of pads. The 8mm oil passage is supported by a combination of 2mm high, 40mm wide and 48.5mm long pads and two 1.5mm high, 30mm wide and 48.5mm long pads. The 8mm oil passage is supported by four 2mm high, 40mm wide and 48.5mm long pads. Support, the pads in the coils between the 22nd and 46th cakes are all made of high heat-resistant grade materials, and the pads between the 1st and 22nd cakes are made of conventional insulating materials; the iron core 3 includes a stem, an upper iron yoke 31 and a lower Iron yoke 32, the core column is composed of stacked silicon steel sheets. When the coil on one side of the transformer is energized, magnetic flux is generated in the iron core to provide a magnetic circuit for the transformer; the core column is inserted into the low-voltage coil 21 and the high-voltage coil 22 from the inside to the outside. , the coils are isolated with screen cardboard and fixed with stays. The stays are made of high-temperature-resistant materials; lead 4 is wrapped with high-temperature-resistant insulating paper, and the end is welded to the end of the coil, and lead 4 is inserted into the casing. to facilitate connection to external circuits.

In summary, in the vegetable oil power transformer provided in this embodiment, the vegetable oil circulating in the oil tank has higher ignition point and flash point and stronger heat resistance than the mineral insulating oil used in the prior art, so as to further improve its cooling and The insulation effect is improved, thereby improving the overload capacity of the transformer, and at the same time improving the fire protection performance of the transformer; through special design of oil passages that circulate vegetable oil, the middle oil passage, end oil passage, first oil passage and third oil passage are The height of the second oil passage is designed to increase the height of the relevant oil passage, thereby overcoming the problem of high viscosity of vegetable oil and making the circulation of vegetable oil more convenient, thus ensuring the overall heat dissipation effect of the transformer and improving the process efficiency of the transformer. load capacity, thereby expanding the use area of the transformer.

In particular, the vegetable oil power transformer provided in this embodiment ensures that the height of the middle oil passage is designed to be increased through a design in which the first dimension value is greater than the fifth dimension value, so as to improve the circulation of vegetable oil in the middle oil passage with poor heat dissipation effect. , thereby improving the heat dissipation effect of the middle oil passage, thereby avoiding the phenomenon of excessive oil temperature, and further improving the overload capacity of the transformer.

Further, in the vegetable oil power transformer provided in this embodiment, the second size value, the third size value and the fourth size value are all smaller than the first size value and greater than or equal to the fifth size value, thereby minimizing the height of the transformer coil. Under these conditions, the overall heat dissipation effect of the transformer is ensured, thereby further avoiding overheating of the oil temperature in the transformer.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the invention. In this way, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims (10)

1. A vegetable oil power transformer, which is characterized in that it includes: an oil tank (1), a cake-type coil (2) and an iron core (3) arranged in the oil tank (1), and is characterized in that: The oil tank (1) is filled with vegetable oil for insulating and cooling the cake coil (2); the oil tank is provided with a pressure release valve; The cake-type coil (2) is provided with several layers of transverse oil channels for the circulation of the vegetable oil, which are arranged at an angle with the axis of the iron core (3); The height of the middle oil passage arranged in the middle is a first size value, the height of several first oil passages on both sides of the middle oil passage is a second size value, and the height of several end oil passages arranged at both ends is third size value; The heights of the several second oil passages above and closest to the first oil passage in the uppermost layer, and the several third oil passages below and nearest to the first oil passage in the lowermost layer are all the fourth size values; The height of the remaining oil passages is the fifth dimension value; The first size value is greater than the fifth size value, and the second size value, the third size value and the fourth size value are all less than the first size value and greater than or equal to the fifth size value. 2. Vegetable oil power transformer according to claim 1, characterized in that, The fourth size value is less than or equal to the second size value. 3. Vegetable oil power transformer according to claim 2, characterized in that, The third size value is equal to the fourth size value. 4. The vegetable oil power transformer according to any one of claims 1 to 3, characterized in that the cake-type coil (2) includes: a low-voltage coil (21) placed outside the iron core (3) in sequence. and high voltage coil (22); where, Gaps are provided in the low-voltage coil (21) and the high-voltage coil (22) in one-to-one correspondence, and the corresponding gaps are connected to form the transverse oil passage for the vegetable oil to circulate. 5. The vegetable oil power transformer according to claim 4, characterized in that, The height of the portion of the intermediate oil passage provided in the low-voltage coil (21) is smaller than the height of the portion provided in the high-voltage coil (22); The height of the portion of the first oil passage disposed in the low-voltage coil (21) is greater than the height of the portion disposed in the high-voltage coil (22). 6. The vegetable oil power transformer according to any one of claims 1 to 3, characterized in that there is a preset distance between the top of the iron core (3) and the top of the oil tank (1). 7. The vegetable oil power transformer according to any one of claims 1 to 3, characterized in that a plurality of stay bars and/or pads for supporting gaps in the oil passage are provided in the oil passage. 8. The vegetable oil power transformer according to claim 7, characterized in that the stays and/or pads provided on the upper part of the oil passage are made of high-temperature resistant insulating materials. 9. The vegetable oil power transformer according to any one of claims 1 to 3, characterized in that, An oil temperature measuring structure is provided on the top of the oil tank (1) for measuring the temperature of the top of the oil tank (1) through an oil temperature measuring device. 10. The vegetable oil power transformer according to any one of claims 1 to 3, characterized in that the insulating paper covering the outer wall of the lead wire (4) of the transformer is high temperature resistant insulating paper.