Transformer insulation structure and preparation method thereof

Abstract

The invention discloses a transformer insulation structure and a preparation method thereof, and relates to the technical field of transformers, the transformer insulation structure comprises an insulation coating material and an air bag, the insulation coating material comprises at least two layers of polymer films, the edges of the two layers of polymer films are connected with each other to form an annular gap, and the air bag is arranged in the annular gap. The two layers of polymer films are used for wrapping a magnetic core or a transformer coil, an expansion microsphere layer is arranged in an annular gap between the two layers of polymer films, the air bag is used for storing inert gas, the air bag is provided with a communicating pipe, and the communicating pipe is communicated with the annular gap. In the application, when the temperature of the transformer rises, the expansion microsphere layer is expanded, so that the annular gap between the two polymer films is enlarged, inert gas is sucked into the annular gap from the air bag, and the insulation effect of the insulation structure is enhanced.

Description

Technical Field

[0001] This application relates to the field of transformers, and in particular to a transformer insulation structure and its preparation method. Background Technology

[0002] A transformer is a device that uses the principle of electromagnetic induction to change alternating current voltage. The insulation performance of a transformer is of great importance to the quality and efficiency of its power supply.

[0003] Currently, in the insulation design of small transformers, insulating materials with a single dielectric constant are often used to cover the magnetic core and windings to prevent current leakage and protect equipment components. However, the performance of the insulating material decreases as the transformer's operating temperature increases, leading to a shorter insulation life and increased maintenance costs and failure risks. Summary of the Invention

[0004] To reduce the impact of increased transformer operating temperature on transformer insulation performance, this application provides a transformer insulation structure and its preparation method.

[0005] This application provides a transformer insulation structure and its preparation method, which adopts the following technical solution: A transformer insulation structure includes an insulating covering material and an air bladder. The insulating covering material comprises at least two polymer films with their edges connected to each other to form an annular gap. The two polymer films are used to wrap a magnetic core or transformer coil. An expandable microsphere layer is disposed in the annular gap between the two polymer films. The air bladder is used to store inert gas and has a connecting tube that communicates with the annular gap.

[0006] By adopting the above technical solution, the polymer film in the transformer provides insulation. Two layers of polymer film are interconnected to form a closed annular gap, which is connected to the connecting pipe of the air bladder, allowing inert gas from inside the air bladder to enter the annular gap. This inert gas also provides auxiliary insulation. When the transformer temperature rises, the temperatures of the two polymer film layers and the expanded microsphere layer rise accordingly, causing the expanded microsphere layer to expand. This increases the size of the annular gap between the two polymer film layers, allowing inert gas to be drawn into the air bladder. The increased spacing between the two polymer film layers and the increased inert gas content both enhance the insulation effect of the insulation structure, reducing the adverse effects of rising transformer temperature on the transformer's insulation performance.

[0007] Optionally, a fabric is filled between the two polymer film layers, and the fabric serves as a carrier for the expanded microsphere layer.

[0008] By adopting the above technical solution, the loose pores of the fabric can serve as a space to accommodate the micro-expansion spheres, and the loose pores of the fabric can adaptively deform as the micro-spheres expand and contract. At the same time, the loose pores of the fabric can also allow for the passage of inert gas.

[0009] Optionally, an elastic coating is provided between the two polymer films. The elastic coating has a strip structure and is bonded to one of the polymer films. The expanded microsphere layer is configured as a strip structure and is located between the bonding surface of the elastic coating and the polymer film connecting the elastic coating.

[0010] By employing the above technical solution, the expanded microspheres are fixed onto the polymer film through an elastic coating, enabling the expanded microsphere layer to maintain a stable ribbon-like structure. The elastic coating possesses elasticity and extensibility, allowing it to adapt to the expansion of the expanded microsphere layer.

[0011] Optionally, multiple elastic films are provided, including transverse elastic films and longitudinal elastic films. The transverse elastic films extend circumferentially along the polymer film, and the longitudinal elastic films are distributed between adjacent transverse elastic films. A gap is left between the two ends of the longitudinal elastic films and the transverse elastic films.

[0012] By adopting the above technical solution, the transverse and longitudinal elastic coatings together form a grid-like structure, making it difficult for the two polymer films to adhere to each other, which is beneficial to improving the diffusion efficiency of inert gas in the annular gap. Furthermore, the longitudinal and transverse elastic coatings have a spacing allowance, which helps to ensure the diffusion efficiency of inert gas.

[0013] Optionally, the connecting tube is configured as a flat structure, and the tube material of the connecting tube is elastic; the connecting tube includes a first connecting tube and a second connecting tube, one end of the first connecting tube is aligned with the inner wall of the airbag, and the other end extends into the inner side of the annular gap, forming a dimensional allowance between the first connecting tube and the inner wall of the annular gap; one end of the second connecting tube is aligned with the inner wall of the annular gap, and the other end extends into the inner cavity of the airbag, forming a dimensional allowance between the second connecting tube and the inner wall of the airbag.

[0014] By adopting the above technical solution, when the airbag expands and contracts, the inert gas mainly enters the annular gap from the first connecting pipe and flows back into the airbag from the second connecting pipe, so that the gas between the airbag and the annular gap forms a backflow phenomenon, which is conducive to the uniform mixing of the gas in the airbag and the annular gap, and makes the insulation effect of various parts in the annular gap more balanced.

[0015] Optionally, the airbag has two main sidewalls, the peripheral edges of which are connected to each other. When the airbag is inflated, it has a pre-stress of contraction; when the airbag is deflated, the two main sidewalls of the airbag abut against each other.

[0016] By adopting the above technical solution, the airbag has contraction stress when inflated. The contraction stress of the airbag makes it easier for the inert gas in the airbag to enter the annular gap between the two polymer films.

[0017] Optionally, the main sidewall is semi-transparent, and the inner surface of one of the two main sidewalls is provided with a dark pattern; the airbag is provided with a valve core.

[0018] The relatively long connection between the two polymer films makes the annular gap between them more prone to micropores that allow gas leakage. By adopting the above technical solution, the main sidewall of the airbag is made semi-transparent. When the airbag is observed through the main sidewall without dark patterns, the dark patterns inside the airbag will change in brightness as the airbag inflates or contracts. This can be used as a basis for judging the amount of gas inside the airbag, so as to replenish the airbag with inert gas.

[0019] Optionally, it also includes a self-healing insulating coating for covering the magnetic core, wherein the material of the self-healing insulating coating is a mixture of insulating coating and microencapsulated repair agent.

[0020] By adopting the above technical solution, the self-healing insulating coating has an insulating function. When the self-healing insulating coating cracks after long-term use, the microcapsules at the cracks will rupture, releasing the internal repair agent to fill the cracks and restore the integrity of the coating.

[0021] Optionally, it also includes a temperature-responsive insulating tape, which includes an insulating substrate and a phase change material layer coated on the surface of the insulating substrate; the temperature-responsive insulating tape is used to cover the magnetic core of the transformer.

[0022] By adopting the above technical solution, the phase change material of temperature-responsive insulating tape generally has a specific phase change temperature. When the temperature rises to the phase change temperature, the phase change material will change from solid to liquid. In this process, a large amount of heat is absorbed, thereby reducing the temperature of the surrounding environment and reducing the impact of high temperature on insulation performance.

[0023] A method for preparing a transformer insulation structure includes the following steps: spraying an insulating coating containing a microencapsulated repair agent onto the surface of a transformer core and curing it to form a self-healing insulating coating; mixing a phase change material with an insulating adhesive and coating it onto the surface of a flexible substrate to prepare a temperature-responsive insulating tape, which is then wrapped around the transformer core; bonding two polymer films together to form an insulating covering material, with an expanded microsphere layer pre-placed between the two polymer films; connecting the insulating covering material and the air bladder using a connecting tube; assembling the prepared components into a transformer and performing insulation performance testing and withstand voltage testing.

[0024] In summary, this application includes at least one of the following beneficial technical effects: When the transformer temperature rises, the temperature of the two polymer film layers and the expanded microsphere layer rises accordingly, causing the expanded microsphere layer to expand and the annular gap between the two polymer film layers to increase. This allows the annular gap to draw inert gas from the air bladder, thereby strengthening the insulation effect of the insulation structure and reducing the adverse effects of the transformer temperature rise on the transformer's insulation effect.

[0025] The self-healing insulating coating has an insulating function. When the self-healing insulating coating cracks after long-term use, the microcapsules at the cracks will rupture, releasing the internal repair agent to fill the cracks and restore the integrity of the coating.

[0026] Temperature-responsive insulating tapes typically use phase change materials with specific phase change temperatures. When the temperature rises to the phase change temperature, the phase change material changes from a solid to a liquid state. During this process, it absorbs a large amount of heat, thereby reducing the temperature of the surrounding environment and minimizing the impact of high temperatures on insulation performance. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the structure of the insulating covering material and the airbag in Example 1.

[0028] Figure 2 yes Figure 1 A magnified view of point A in the middle.

[0029] Figure 3 This is a schematic diagram of the end of the insulating coating material in Example 1.

[0030] Figure 4 This is a cross-sectional view of the structure of the insulating covering material and the airbag in Example 2.

[0031] Figure 5 yes Figure 4 A magnified view of point B in the middle.

[0032] Figure 6 This is a schematic diagram showing the distribution of the transverse and longitudinal elastic coatings on the unfolded polymer film in Example 2.

[0033] Explanation of reference numerals in the attached figures: 1. Insulating coating material; 11. Polymer film; 12. Annular slit; 13. Expanded microsphere layer; 2. Connecting tube; 21. First connecting tube; 22. Second connecting tube; 3. Elastic coating; 31. Transverse elastic coating; 32. Longitudinal elastic coating; 4. Airbag; 41. Main sidewall; 42. Valve core. Detailed Implementation

[0034] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.

[0035] Example 1: This application discloses a transformer insulation structure. The transformer insulation structure includes a self-healing insulating coating, a temperature-responsive insulating tape, an epoxy board for the transformer side posts, and an insulating covering material 1.

[0036] Reference Figure 1 and Figure 2 The insulating coating material 1 includes at least two polymer films 11. The polymer film 11 is made of polyurethane film, polyimide or polyetherimide, etc. The edges of the two polymer films 11 are connected to each other to form an annular gap 12. The two polymer films 11 are used to wrap the magnetic core or transformer coil. An expanded microsphere layer 13 is provided in the annular gap 12 between the two polymer films 11.

[0037] A fabric is filled between the two polymer film layers 11, serving as a carrier for the expanded microsphere layer 13. The loose pores of the fabric can provide space for the micro-expanded spheres, while also allowing inert gas to pass through.

[0038] Reference Figure 1 The airbag 4 is used to store inert gas. The airbag 4 is elongated in shape and has two main sidewalls 41. The material of the main sidewalls 41 is a rubber, silicone or TPU or other elastic polymer material. The material of the main sidewalls 41 is semi-transparent. The two main sidewalls 41 are connected to each other at their peripheral edges. The connection between the main sidewalls 41 can be by adhesive or integral connection. When the airbag 4 is in the inflated state, the airbag 4 has a pre-stress of contraction. When the airbag 4 is in the deflated state, the two main sidewalls 41 of the airbag 4 abut against each other. The airbag 4 is equipped with a valve core 42.

[0039] When in use, the airbag 4 can be connected end to end to form a ring structure, allowing it to be fitted onto one end of a magnetic core or coil. The inner surface of the inner sidewall 41 of the two main sidewalls 41 of the airbag 4 has a dark pattern. The main sidewall 41 is semi-transparent; when observing the airbag 4 through the sidewall 41 without the dark pattern, the dark pattern inside the airbag 4 changes in brightness as the airbag 4 inflates or deflates. This serves as a basis for determining the amount of gas inside the airbag 4, facilitating the replenishment of inert gas in case of leakage.

[0040] Reference Figure 1 and Figure 2 The airbag 4 is provided with a connecting tube 2, which is connected to the annular gap 12. The connecting tube 2 is designed with a flat structure and the tube material of the connecting tube 2 is elastic. The connecting tube 2 includes a first connecting tube 21 and a second connecting tube 22. One end of the first connecting tube 21 is aligned with the inner wall of the airbag 4, and the other end extends into the inner side of the annular gap 12, forming a dimensional allowance between the first connecting tube 21 and the inner wall of the annular gap 12. One end of the second connecting tube 22 is aligned with the inner wall of the annular gap 12, and the other end extends into the inner cavity of the airbag 4, forming a dimensional allowance between the second connecting tube 22 and the inner wall of the airbag 4.

[0041] When the airbag 4 expands and contracts, the inert gas mainly enters the annular gap 12 from the first connecting pipe 21 and flows back into the airbag 4 from the second connecting pipe 22, causing the gas between the airbag 4 and the annular gap 12 to form a backflow phenomenon. This helps to mix the gas in the airbag 4 and the annular gap 12 evenly, making the insulation effect of each part in the annular gap 12 more balanced.

[0042] The working principle of the insulating coating material 1 is as follows: the two polymer films 11 of the insulating coating material 1 are interconnected to form a closed annular gap 12, and the annular gap 12 is connected to the air bladder 4, allowing the inert gas inside the air bladder 4 to enter the annular gap 12. The inert gas also plays an auxiliary insulating role. When the transformer temperature rises, the expanding microsphere layer 13 expands, increasing the size of the annular gap 12 between the two polymer films 11. This allows the annular gap 12 to draw inert gas from the air bladder 4, thereby strengthening the insulation effect of the insulating structure and reducing the adverse effects of transformer temperature rise on the transformer's insulation performance.

[0043] A self-healing insulating coating is used to cover the surface of the magnetic core; the material of the self-healing insulating coating is a mixture of insulating paint and microencapsulated repair agent. Transformer end-column epoxy boards are used to connect to the magnetic core and are connected to the self-healing insulating coating. The interior of the transformer end-column epoxy board has a gradient dielectric constant insulation structure, which consists of multiple layers of insulation with different dielectric constants. Temperature-responsive insulating tape is used to wrap around the periphery of the magnetic core; the temperature-responsive insulating tape includes an insulating substrate and a phase change material layer coated on the surface of the insulating substrate.

[0044] When self-healing insulating coatings crack after long-term use, the microcapsules at the cracks rupture, releasing the internal repair agent to fill the cracks and restore the coating's integrity. Temperature-responsive insulating tapes absorb a large amount of heat during phase change, thus reducing the impact of high temperatures on insulation performance. Transformer side post epoxy boards have an internal gradient dielectric constant insulation structure, which optimizes the electric field distribution and reduces the problem of excessively high local electric field strength accelerating insulation material aging and damage.

[0045] This embodiment also discloses the above-mentioned method for preparing the transformer insulation structure, including the following steps: Step 1: Spray the insulating coating containing microencapsulated repair agent onto the surface of the transformer core and cure it to form a self-healing insulating coating. In this step, the microencapsulated repair agent is evenly mixed with the insulating coating and then evenly sprayed onto the surface of the transformer core. The coated core is then placed in a curing device for heating and curing, with the curing temperature controlled within the range of 80℃ to 120℃. Step 2: Lay insulating materials with different dielectric constants layer by layer inside the epoxy board of the transformer side column and cure them to form a gradient dielectric constant insulation system; In this step, insulating materials with appropriate dielectric constants are selected and alternately laminated with reinforcing materials, and then combined with epoxy resin impregnation to form transformer side post epoxy boards. The transformer side post epoxy boards are placed in a curing device for curing, so that a gradient dielectric constant insulation structure is formed inside the transformer side post epoxy boards. In this step, the insulating materials are ceramics, mica, etc., and the reinforcing materials are carbon fiber, glass fiber, aramid fiber, etc.

[0046] Step 3: Mix the phase change material with the insulating adhesive, coat it on the surface of the flexible substrate to prepare a temperature-responsive insulating tape, and wrap it around the transformer core. In this step, the phase change material and insulating adhesive are mixed at a mass ratio of 2:8 to 1:9. The phase change material is a phase change temperature sensitive material, usually paraffin or rosin; the insulating adhesive can be epoxy resin, polyester resin, etc. After mixing, it is coated on the surface of a flexible substrate, such as PU film or PVC film, to make a temperature-responsive insulating tape. Step 4: The two polymer films 11 are bonded together to form an insulating coating material 1. An expanded microsphere layer 13 is pre-placed between the two polymer films 11. During the bonding process of the two polymer films 11, the connecting tube 2 is bonded to the two polymer films 11. Then, the two main sidewalls 41 of the airbag 4 are bonded together and simultaneously bonded to the connecting tube 2. After the insulating coating material 1 is wrapped around the magnetic core or coil, a ring structure is formed. Step 5: Assemble the prepared components into a transformer, and conduct insulation performance tests and withstand voltage tests to ensure that it meets the design requirements.

[0047] It is worth mentioning that, in another embodiment, the airbag 4 in this application can be configured to be integrally connected with the connecting pipe 2. Accordingly, the connecting pipe 2 only needs to be connected to the insulating covering material 1.

[0048] Example 2: The transformer insulation structure in this example is different from that in Example 1. The difference between this example and Example 1 is that the carrier of the expanded microsphere layer 13 is different in this example.

[0049] Reference Figure 4 , Figure 5 and Figure 6 In this embodiment, an elastic film 3 is provided between the two polymer films 11. The elastic film is made of materials such as rubber, silicone, or TPU. The elastic film 3 has a strip structure, and its two ends and side edges are bonded and fixed to the polymer film 11. The expandable microsphere layer 13 is also set as a strip structure and is located between the elastic film 3 and the polymer film 11 connecting the elastic film 3, so that the elastic film 3 serves as a carrier for the expandable microsphere layer 13. The elastic film 3 has elasticity and extensibility, and when the expandable microsphere layer 13 expands or contracts, the elastic film 3 can produce adaptive stretching and deformation.

[0050] Reference Figure 4 The elastic film 3 is provided with multiple elastic films, including a transverse elastic film 31 and a longitudinal elastic film 32. The transverse elastic film 31 extends along the circumference of the polymer film 11, and the longitudinal elastic film 32 is distributed between adjacent transverse elastic films 31. A gap is left between the two ends of the longitudinal elastic film 32 and the transverse elastic film 31.

[0051] The transverse elastic coating 31 and the longitudinal elastic coating 32 together form a grid-like structure, making it difficult for the two polymer films 11 to adhere to each other, which is beneficial to improving the diffusion efficiency of inert gas in the annular gap 12. Furthermore, the spacing between the longitudinal elastic coating 32 and the transverse elastic coating 31 helps to further ensure the diffusion efficiency of inert gas.

[0052] In this embodiment, the step of preparing the insulating covering material 1 in the transformer insulation structure preparation method is different from that in Embodiment 1.

[0053] In this embodiment, when preparing the insulating coating material 1, one layer of polymer film 11 is first laid flat on a horizontal surface, and then a template with strip holes is laid on the polymer film 11. Next, expanded microsphere powder is filled into the strip holes of the template. Lay the second polymer film 11 flat on a horizontal surface, and then use double-sided tape or solid adhesive to bond the elastic film 3 to the second polymer film 11, so that the position of the elastic film 3 corresponds to the position of the expanded microsphere powder on the first layer; then apply adhesive to the side of the elastic film 3 that is not covered with dots of adhesive, and then cover the elastic film 3 with the expanded microsphere powder. After the elastic film 3 and the first polymer film 11 are bonded and cured, the second polymer film 11 is removed and the double-sided tape or solid adhesive is removed; after completion, the connection between the two polymer films 11 and the airbag 4 is completed according to the steps of Example 1.

[0054] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A transformer insulation structure, characterized in that: The device includes an insulating covering material (1) and an air bladder (4). The insulating covering material (1) includes at least two polymer films (11). The edges of the two polymer films (11) are connected to each other to form an annular gap (12). The two polymer films (11) are used to wrap a magnetic core or transformer coil. An expanded microsphere layer (13) is provided in the annular gap (12) between the two polymer films (11). The air bladder (4) is used to store inert gas. The air bladder (4) is provided with a connecting tube (2). The connecting tube (2) is connected to the annular gap (12).

2. The transformer insulation structure according to claim 1, characterized in that: A fabric is provided between the two polymer film (11) layers, which serves as a carrier for the expanded microsphere layer (13).

3. The transformer insulation structure according to claim 1, characterized in that: An elastic coating (3) is provided between the two polymer films (11). The elastic coating (3) has a strip structure and is bonded to one of the polymer films (11). The expanded microsphere layer (13) is configured as a strip structure and is located between the bonding surface of the elastic coating (3) and the polymer film (11) connecting the elastic coating (3).

4. The transformer insulation structure according to claim 3, characterized in that: The elastic film (3) is provided in multiple layers. The elastic film (3) includes a transverse elastic film (31) and a longitudinal elastic film (32). The transverse elastic film (31) extends circumferentially along the polymer film (11). The longitudinal elastic film (32) is distributed between adjacent transverse elastic films (31). There is a gap allowance between the two ends of the longitudinal elastic film (32) and the transverse elastic film (31).

5. A transformer insulation structure according to claim 1, characterized in that: The connecting pipe (2) is configured as a flat structure, and the pipe material of the connecting pipe (2) is elastic; the connecting pipe (2) includes a first connecting pipe (21) and a second connecting pipe (22). One end of the first connecting pipe (21) is aligned with the inner wall of the airbag (4), and the other end extends into the inner side of the annular gap (12), forming a dimensional allowance between it and the inner wall of the annular gap (12); one end of the second connecting pipe (22) is aligned with the inner wall of the annular gap (12), and the other end extends into the inner cavity of the airbag (4), forming a dimensional allowance between it and the inner wall of the airbag (4).

6. The transformer insulation structure according to claim 1, characterized in that: The airbag (4) has two main sidewalls (41), and the peripheral edges of the two main sidewalls (41) are connected to each other. When the airbag (4) is in an inflated state, the airbag (4) has a pre-stress of contraction. When the airbag (4) is in an emptied state, the two main sidewalls (41) of the airbag (4) abut against each other.

7. A transformer insulation structure according to claim 6, characterized in that: The main sidewall (41) is semi-transparent, and the inner surface of one of the two main sidewalls (41) is provided with a dark pattern; the airbag (4) is provided with a valve core (42).

8. A transformer insulation structure according to claim 1, characterized in that: It also includes a self-healing insulating coating for covering the magnetic core, wherein the material of the self-healing insulating coating is a mixture of insulating coating and microencapsulated repair agent.

9. A transformer insulation structure according to claim 8, characterized in that: It also includes temperature-responsive insulating tape, which comprises an insulating substrate and a phase change material layer coated on the surface of the insulating substrate; the temperature-responsive insulating tape is used to cover the magnetic core of a transformer.

10. A method for preparing a transformer insulation structure according to any one of claims 8-9, characterized in that, Includes the following steps: The insulating coating containing microencapsulated repair agent is sprayed onto the surface of the transformer core and cured to form a self-healing insulating coating. A temperature-responsive insulating tape is prepared by mixing phase change material with insulating adhesive and coating it on the surface of a flexible substrate, and then wrapping it around the transformer core. Two polymer films (11) are bonded together to form an insulating coating material (1), and an expanded microsphere layer (13) is pre-set between the two polymer films (11); the insulating coating material (1) and the airbag (4) are connected by a connecting tube (2). The prepared components are assembled into a transformer, and insulation performance and withstand voltage tests are conducted.

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