High-voltage coil, epoxy resin poured dry-type transformer and winding method

Abstract

The invention relates to a high-voltage coil, an epoxy resin poured dry-type transformer and a winding method, the high-voltage coil comprises a plurality of cylindrical coils which are arranged along the axial direction, and a radial air channel which extends along the radial direction is arranged between two adjacent cylindrical coils so as to communicate the inner space and the outer space of the coil. The winding method of the high-voltage coil comprises the following steps of: 1, sequentially winding a first group of coils and a second group of coils, vertically placing the first group of coils and the second group of coils in a mold up and down, placing a second air passage plate between two adjacent cylindrical coils in each group, and placing a first air passage plate between the first group of coils and the second group of coils; and 2, placing the mold with the coil at the environment temperature of 100-120 DEG C for 8-12 hours, pouring epoxy resin into the coil in vacuum, curing after pouring, and removing the mold, the first air passage plate and the second air passage plate after curing, thereby obtaining the high-voltage coil with the radial air passage. The radial air passages are beneficial to circulation of air inside and outside the coil, so that the heat dissipation performance of the coil can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of transformers, and in particular relates to a high-voltage coil, an epoxy resin-cast dry-type transformer, and a winding method of the high-voltage coil. Background Art

[0002] There are two types of dry-type transformers at present. One is an open dry-type transformer, which is generally an H-class insulation impregnation type. Its coil is made of glass fiber wrapped wire or Nomex paper wrapped wire, wound into a pancake coil. After being impregnated with insulating varnish, the coil is not encapsulated in any way, so it is also called an open dry-type transformer. The biggest advantage of this transformer is that each turn of wire is in contact with the cooling air, and the heat dissipation performance is good, but the biggest disadvantage is that dust is easily deposited on the horizontal surface of the coil. If the moisture resistance of the impregnation varnish is not good, the transformer is easily affected by moisture and has poor anti-fouling ability. The other is an epoxy resin cast dry-type transformer, which generally adopts a segmented cylindrical structure and an axial heat dissipation airway. The specific structure is as follows: Figures 1 to 3 As shown, the disadvantage is that insulation needs to be laid between the layers of the segmented cylindrical coil in the prior art, and the heat dissipation air duct needs to be laid after the inner segmented coil is wound and then the outer segmented coil is wound, which requires multiple back and forth cycles and is inefficient. At the same time, the insulating cylinder placed between the high and low voltage coils in the prior art is a whole, and the internal and external gases are not interconnected, so the heat dissipation effect is poor for the low voltage coil.

[0003] At the same time, the electric field on the coil surface of the dry-type transformer in the prior art is uneven, which can easily cause the coil insulation to be damaged due to the high local electric field. Summary of the invention

[0004] The first technical problem to be solved by the present invention is to provide a high-voltage coil in view of the current status of the prior art to improve its heat dissipation performance.

[0005] The second technical problem to be solved by the present invention is to provide a high voltage coil which can improve the winding efficiency.

[0006] The third technical problem to be solved by the present invention is to provide an epoxy resin cast dry-type transformer having the above-mentioned high-voltage coil.

[0007] The fourth technical problem to be solved by the present invention is to provide a method for winding the above-mentioned high-voltage coil.

[0008] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a high-voltage coil, including a plurality of cylindrical coils arranged along the axial direction, characterized in that: a radially extending radial airway is provided between two adjacent cylindrical coils to connect the inner and outer spaces of the cylindrical coils.

[0009] By arranging radially extending radial air passages between the segmented cylindrical coils, it is beneficial for the air to circulate inside and outside the coils, thereby improving the heat dissipation performance of the coils.

[0010] To further improve the heat dissipation performance, preferably, there are at least two radial air passages between two adjacent cylindrical coils, and the air passages are spaced apart along the circumference of the coils.

[0011] To further solve the second technical problem, preferably, when enameled wire is used and the thickness of the enameled insulation is not less than 0.12 mm, the maximum interlayer voltage is allowed to be 265V, and the number of turns, voltage per turn and insulation thickness of a single cylindrical coil meet the following conditions: (number of turns × voltage per turn × 2) / insulation thickness per turn < 2200V / m; when film-wrapped wire is used and the film-wrapped insulation is not less than 0.3 mm, the maximum interlayer voltage is allowed to be 400V, and the number of turns, voltage per turn and insulation thickness of a single cylindrical coil meet the following conditions: (number of turns × voltage per turn × 2) / insulation thickness per turn < 1350V / m. This eliminates the need to lay insulating materials such as mesh cloth, insulating paper, and insulating cloth between the layers of each cylindrical coil, thereby facilitating the winding of the coil and improving the winding efficiency of the coil.

[0012] In the above schemes, preferably, the plurality of cylindrical coils are divided into two groups along the axial direction, namely, a first group of coils and a second group of coils, and the outgoing wire of the first cylindrical coil of two adjacent cylindrical coils in each group is the incoming wire of the second cylindrical coil, and the first cylindrical coil, the second cylindrical coil and the incoming and outgoing wires therebetween are arranged in a Z shape;

[0013] The radial air passage between the first group of coils and the second group of coils is referred to as the first radial air passage, and the radial air passage between two adjacent cylindrical coils in each group is referred to as the second radial air passage.

[0014] Preferably, a height dimension of the first radial air passage along the axial direction is greater than a height dimension of the second radial air passage.

[0015] Furthermore, the axial direction is taken as the up-down direction, and the first radial airway is arranged upward from the central position of the high-voltage coil in the up-down direction. When in use, the temperature of the position above the center of the coil is higher, and the first radial airway arranged upward in the present invention is conducive to improving the heat dissipation performance of the coil.

[0016] The technical solution adopted by the present invention to solve the above-mentioned third technical problem is: an epoxy resin cast dry-type transformer, comprising an iron core, a low-voltage winding wound on the outer periphery of the iron core, a high-voltage winding wound on the outer periphery of the low-voltage winding, and an insulating tube arranged between the low-voltage winding and the high-voltage winding, characterized in that: the high-voltage winding adopts the high-voltage coil as described above.

[0017] In order to ensure insulation and facilitate heat dissipation, preferably, the insulating cylinder includes:

[0018] The two sections of insulating cylinders are arranged along the axial direction and the two adjacent ends are arranged inside and outside to form an annular gap, and the annular gap is arranged corresponding to the first radial airway. The annular gap between the two sections of insulating cylinders is conducive to the flow of airflow, thereby facilitating heat dissipation. At the same time, since the two adjacent ends of the two sections of insulating cylinders are arranged inside and outside, the insulation effect can be guaranteed.

[0019] Furthermore, the two sections of insulating cylinder are connected and are both constrained together with the low-voltage winding, and the height dimension of the annular gap in the axial direction is not less than 20 mm.

[0020] The technical solution adopted by the present invention to solve the fourth technical problem is: a method for winding a high-voltage coil as described above, characterized in that the steps are as follows:

[0021] 1. Wind the first group of coils and the second group of coils in sequence, and place them upright one above the other in a mold, with a second airway plate placed between two adjacent cylindrical coils in the first group of coils and the second group of coils, and a first airway plate placed between the first group of coils and the second group of coils;

[0022] 2. Place the mold containing the first and second groups of coils at an ambient temperature of 100-120°C for 8-12 hours, then evacuate the coils and pour epoxy resin, and then cure them after pouring. After curing, remove the mold and the first and second airway plates to obtain a high-voltage coil with radial airways.

[0023] The winding method of the present invention can effectively improve the winding efficiency.

[0024] Preferably, the high-voltage coil with radial air passages obtained in step 2 above can be placed in a vacuum tank filled with semiconductor liquid insulating material for soaking, and the soaking is repeated 2 to 5 times, and then removed and solidified, so that a semiconductor layer is formed on the surface of the high-voltage coil. The uniform semiconductor layer on the coil surface makes the electric field on the coil surface more uniform, and the insulation performance of the coil is better.

[0025] Compared with the prior art, the present invention has the advantages that by providing radially extending radial air passages between the segmented cylindrical coils, the circulation of air inside and outside the coils is facilitated, thereby improving the heat dissipation performance of the coils.

[0026] The present invention not only retains the advantages of dustproof, anti-fouling, compact structure and small size of epoxy resin cast dry-type transformer, but also has the advantages of good heat dissipation of open dry-type transformer, and has higher production efficiency. The coil can be wound at one time, and the efficiency is increased by at least 4 times. The insulating cylinder divided into two sections enables the low-voltage winding to obtain more heat dissipation airflow, and the low-voltage winding has better heat dissipation. The uniform semiconductor layer on the surface of the coil makes the electric field on the surface of the coil more uniform, and the insulation performance of the coil is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A top view of an existing epoxy-cast dry-type transformer;

[0028] Figure 2 Front view of the existing epoxy resin cast dry-type transformer;

[0029] Figure 3 A longitudinal cross-sectional view of an existing epoxy resin cast dry-type transformer;

[0030] Figure 4 is a longitudinal cross-sectional view of a high voltage coil according to a first embodiment of the present invention;

[0031] Figure 5 A longitudinal cross-sectional view of an epoxy resin cast dry-type transformer according to Embodiment 1 of the present invention;

[0032] Figure 6 A top view of an epoxy resin cast dry-type transformer according to Embodiment 1 of the present invention;

[0033] Figure 7 This is a front view of the epoxy resin cast dry-type transformer according to the first embodiment of the present invention;

[0034] Figure 8 A top view of one of the airway plates in the first embodiment of the present invention;

[0035] Fig. 9 for Figure 8 Front view of the middle airway plate;

[0036] Fig.10 A top view of another airway plate according to the first embodiment of the present invention;

[0037] Fig.11 for Fig.10 Front view of the middle airway plate;

[0038] Fig.12 A longitudinal cross-sectional view of an epoxy resin cast dry-type transformer according to the second embodiment of the present invention;

[0039] Fig.13 This is a longitudinal cross-sectional view of an epoxy resin cast dry-type transformer according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to the accompanying drawings.

[0041] Embodiment 1:

[0042] like Figures 4 to 11 As shown, a preferred embodiment 1 of a high-voltage coil, an epoxy resin cast dry-type transformer and a winding method of the present invention is shown. The epoxy resin cast dry-type transformer includes an iron core 2, a low-voltage winding 3 wound around the outer periphery of the iron core 2, a high-voltage winding 4 wound around the outer periphery of the low-voltage winding 3, and an insulating tube 5 arranged between the low-voltage winding 3 and the high-voltage winding 4.

[0043] There is an axial air passage between the iron core 2 and the low-voltage winding 3 .

[0044] The high-voltage winding 4 includes four cylindrical coils 1 arranged in the axial direction (i.e., in the up-down direction), and there is a radial airway 10 extending radially between two adjacent cylindrical coils 1 to connect the inner and outer spaces of the cylindrical coils, and there are four radial airways 10 located between two adjacent cylindrical coils 1, and they are arranged at intervals along the circumference of the coils. In this embodiment, the four cylindrical coils 1 are divided into two groups in pairs, namely, the first group of coils 1a of the two cylindrical coils 1 located on the upper side and the second group of coils 1b of the two cylindrical coils 1 located on the lower side. The outlet line of the first cylindrical coil of the two adjacent cylindrical coils 1 in each group is the inlet line of the second cylindrical coil, and the first cylindrical coil, the second cylindrical coil and the inlet and outlet lines between the two are arranged in a Z shape. At the same time, the radial airway 10 located between the first group of coils 1a and the second group of coils 1b is recorded as the first radial airway 101, and the radial airway 10 between the two adjacent cylindrical coils 1 in each group is recorded as the second radial airway 102. The height dimension H1 of the first radial air passage 101 in the vertical direction is greater than the height dimension H2 of the second radial air passage 102. And the first radial air passage 101 is located at the center of the high voltage winding.

[0045] At the same time, in this embodiment, when enameled wire is used and the thickness of the enameled insulation is not less than 0.12mm, the maximum interlayer voltage is allowed to be 265V, and the number of turns of a single cylindrical coil 1, the voltage per turn, and the insulation thickness of the turns meet the following conditions: (number of turns × voltage per turn × 2) / insulation thickness per turn < 2200V / m. When film-wrapped wire is used and the film-wrapped insulation is not less than 0.3mm, the maximum interlayer voltage is allowed to be 400V, and the number of turns of a single cylindrical coil 1, the voltage per turn, and the insulation thickness of the turns meet the following conditions: (number of turns × voltage per turn × 2) / insulation thickness per turn < 1350V / m. This makes it unnecessary to place insulation between layers.

[0046] like Figure 5As shown, the insulating cylinder 5 includes two connected upper and lower insulating cylinder bodies 50, the inner diameter of the upper insulating cylinder body is larger than the inner diameter of the lower insulating cylinder body, the lower end of the upper insulating cylinder body is sleeved on the outer periphery of the upper end of the lower insulating cylinder body, and an annular gap 51 is formed between the two, the annular gap 51 is arranged corresponding to the first radial airway 101, and the height dimension H3 of the annular gap 51 in the axial direction is not less than 20 mm. At the same time, in this embodiment, the two insulating cylinder bodies 50 and the low-voltage winding are bonded by stays.

[0047] The steps of winding the high voltage winding in this embodiment are as follows:

[0048] 1. Wind the first group of coils 1a and the second group of coils 1b in sequence, and place them vertically in the mold one above the other. A second airway plate is placed between two adjacent cylindrical coils 1 in the first group of coils 1a and the second group of coils 1b, and a first airway plate is placed between the first group of coils 1a and the second group of coils 1b. The shapes of the first and second airway plates are designed according to the shapes of the cross sections of the high-voltage windings, as shown in the following example: Figure 8 , 10 The shape shown;

[0049] 2. Place the mold with the first set of coils 1a and the second set of coils 1b at an ambient temperature of 100-120°C for 8-12 hours, then evacuate the coils, pour epoxy resin, and cure after pouring. After curing, remove the mold and the first and second airway plates to obtain a high-voltage coil with radial airways 10. The evacuation, pouring epoxy resin and curing processes are prior art and will not be described in detail.

[0050] 3. Move the high-voltage coil with radial air passage 10 obtained in step 2 above into a vacuum tank filled with semiconductor liquid insulation material and soak it for 2 to 5 times, then remove it and solidify it. In this way, there is a semiconductor layer on the surface of the high-voltage coil, making the electric field on the surface of the coil uniform, and avoiding the coil insulation damage caused by the high local electric field.

[0051] Specifically, the method for winding a single set of coils in step 1 is:

[0052] Fix the incoming wire at the starting position, and start to continuously wind the first layer of the first cylindrical coil according to the winding direction specified in the drawing. After the first layer is wound, make an S-bend on the wire, and use insulating paper such as DMD or HSH to fold it into a U-shaped hoop around the bending area, and then go up to wind the second layer; then continue to wind to the last layer of the first cylindrical coil according to the above winding method; after the last layer of the first cylindrical coil is wound, bend the wire so that the outgoing wire of the first cylindrical coil is the incoming wire of the second cylindrical coil, and then wind the first layer and the second layer of the second cylindrical coil on the mold in sequence until the last layer.

[0053] And in this embodiment, if Figure 7 As shown, six taps are led out from the middle part of the high-voltage coil in the axial direction, namely tap 2, tap 3, tap 4, tap 5, tap 6, and tap 7. The tap leading method is the existing technology and will not be described in detail.

[0054] Embodiment 2:

[0055] like Fig.12 As shown, a preferred embodiment 2 of a high-voltage coil, an epoxy resin cast dry-type transformer and a winding method of the present invention is shown. This embodiment is basically the same as the embodiment 1, except that in this embodiment, the first radial airway 101 is arranged upwardly away from the central position in the up-down direction of the high-voltage coil. Specifically, the first radial airway 101 is located at 2 / 3 of the height of the high-voltage winding itself.

[0056] Embodiment three:

[0057] like Fig.13 As shown, a preferred embodiment 3 of a high-voltage coil, an epoxy resin cast dry-type transformer and a winding method of the present invention is shown. This embodiment is basically the same as the first embodiment, except that in this embodiment, the first group of coils 1a has 8 cylindrical coils 1, and the second group of coils 1b has 8 cylindrical coils 1.

[0058] In the specification and claims of the present invention, terms indicating directions, such as "front", "rear", "up", "down", "left", "right", "side", "top", "bottom", etc., are used to describe various exemplary structural parts and elements of the present invention, but these terms are used here only for the purpose of convenience of description and are determined based on the exemplary orientations shown in the accompanying drawings. Since the embodiments disclosed in the present invention can be arranged in different directions, these terms indicating directions are only used as explanations and should not be regarded as limitations. For example, "up" and "down" are not necessarily limited to directions opposite to or consistent with the direction of gravity.

[0059] The term "vertical" is also used in the specification and claims of the present invention, which means basically along the up and down direction, and is not limited to the vertical direction only, and can also be slightly inclined relative to the vertical direction.

[0060] The term "radial" is also used in the specification and claims of the present invention, which means basically along the inward and outward direction, and is not limited to the radial direction passing through the center of the circle, and can also be slightly deviated from the radial direction.

Claims

1. A high voltage coil, comprising a plurality of cylindrical coils (1) arranged along an axial direction, characterized in that: A radially extending radial air passage (10) is provided between two adjacent cylindrical coils (1) to connect the inner and outer spaces of the cylindrical coils.

2. The high voltage coil according to claim 1, characterized in that: There are at least two radial air passages (10) between two adjacent cylindrical coils (1), and the air passages (10) are arranged at intervals along the circumference of the coils.

3. The high voltage coil according to claim 1, characterized in that: When enameled wire is used and the thickness of the enameled insulation is not less than 0.12 mm, the maximum interlayer voltage is allowed to be 265 V, and the number of turns, voltage per turn and insulation thickness of a single cylindrical coil (1) satisfy the following relationship: (number of turns × voltage per turn × 2) / insulation thickness per turn < 2200 V / m; when film-wrapped wire is used and the film-wrapped insulation is not less than 0.3 mm, the maximum interlayer voltage is allowed to be 400 V, and the number of turns, voltage per turn and insulation thickness of a single cylindrical coil (1) satisfy the following relationship: (number of turns × voltage per turn × 2) / insulation thickness per turn < 1350 V / m.

4. The high voltage coil according to any one of claims 1 to 3, characterized in that: A plurality of cylindrical coils are divided into two groups along the axial direction, namely a first group of coils (1a) and a second group of coils (1b); the outgoing wire of the first cylindrical coil of two adjacent cylindrical coils (1) in each group is the incoming wire of the second cylindrical coil, and the first cylindrical coil, the second cylindrical coil and the incoming and outgoing wires therebetween are arranged in a Z shape; The radial air passage (10) between the first group of coils (1a) and the second group of coils (1b) is referred to as the first radial air passage (101), and the radial air passage (10) between two adjacent cylindrical coils (1) in each group is referred to as the second radial air passage (102).

5. The high voltage coil according to claim 4, characterized in that: The height dimension of the first radial air passage (101) along the axial direction is greater than the height dimension of the second radial air passage (102).

6. The high voltage coil according to claim 4, characterized in that: The axial direction is the up-down direction, and the first radial airway (101) is arranged upwardly, deviating from the central position in the up-down direction of the high-voltage coil.

7. An epoxy resin cast dry-type transformer, comprising an iron core (2), a low voltage winding (3) wound around the outer periphery of the iron core (2), a high voltage winding (4) wound around the outer periphery of the low voltage winding (3), and an insulating cylinder (5) arranged between the low voltage winding (3) and the high voltage winding (4), characterized in that: The high-voltage winding (4) adopts the high-voltage coil as claimed in any one of claims 4 to 6.

8. The epoxy resin cast dry-type transformer according to claim 7, characterized in that: The insulating cylinder (5) comprises: Two sections of insulating cylinders (50) are arranged along the axial direction and are disposed inside and outside two adjacent ends to form an annular gap (51), and the annular gap (51) is arranged corresponding to the first radial air channel (101).

9. The epoxy resin cast dry-type transformer according to claim 8, characterized in that: The two sections of insulating cylinder (50) are connected and are both constrained together with the low-voltage winding (3); the height dimension of the annular gap (51) in the axial direction is not less than 20 mm.

10. A method for winding a high voltage coil as claimed in any one of claims 4 to 6, characterized in that Here are the steps:

1. Winding a first group of coils (1a) and a second group of coils (1b) in sequence, and placing the two coils one above the other in a mold, with a second airway plate placed between two adjacent cylindrical coils (1) in the first group of coils (1a) and the second group of coils (1b), and a first airway plate placed between the first group of coils (1a) and the second group of coils (1b); Second, the mold containing the first group of coils (1a) and the second group of coils (1b) is placed at an ambient temperature of 100 to 120°C for 8 to 12 hours, and then the coils are evacuated and poured with epoxy resin. After pouring, the coils are cured. After curing, the mold and the first and second airway plates are removed to obtain a high-voltage coil with a radial airway (10).

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