A voltage transformer body and a manufacturing method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN NORTH INSTR TRANSFORMER GROUP
- Filing Date
- 2026-07-06
- Publication Date
- 2026-08-07
AI Technical Summary
[0005]本发明的目的在于，提供一种电压互感器器身及其制作方法，以解决铁芯因接触环氧树脂或承受浇注固化应力而导致的励磁特性劣化问题，同时解决装模过程中器身定位不可靠、绝缘距离均匀性差、产品励磁特性分散性大的技术难题
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Figure CN122531970A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of transformer manufacturing technology, specifically to a voltage transformer body and its manufacturing method. Background Technology
[0002] Voltage transformers are crucial measurement and protection devices in power systems, and their operational reliability directly impacts the safety and stability of the power grid. During operation, the excitation characteristics of the transformer core are one of the core parameters determining the product's performance. The consistency of these core excitation characteristics not only affects the transformer's measurement accuracy but also the reliability of its protection actions during system faults.
[0003] Currently, in the field of instrument transformer manufacturing, the body of voltage transformers is typically fabricated using a process where the coil is directly wound around an iron core and then vacuum-cast with epoxy resin. In this process, the iron core is isolated and protected from the external insulating medium only by a buffer wrapping material. However, the existing iron core protection methods have significant shortcomings: to ensure the isolation effect between the iron core and the casting resin, it is usually necessary to increase the number and thickness of the buffer wrapping layers on the iron core, which inevitably increases the size of the transformer body, reduces structural redundancy in the product design, and significantly increases material costs; if the vacuum level of vacuum casting is reduced to decrease resin penetration, it will increase porosity defects inside the casting body, reducing the insulation strength and service life of the product. Both methods are passive coping strategies and fail to solve the problem at its root.
[0004] In-depth analysis revealed that the root cause of the aforementioned problems lies in the lack of a stable and reliable physical isolation layer between the iron core and the epoxy resin in traditional processes. During vacuum casting, low-viscosity epoxy resin easily seeps into the iron core through the tiny gaps between the core and the wrapping material. Simultaneously, the epoxy resin generates significant volume shrinkage stress during high-temperature curing, which directly acts on the iron core surface, leading to a decrease in core permeability, increased losses, and irreversible changes in excitation characteristics. This problem of core performance degradation caused by resin intrusion and stress still lacks an effective solution. Furthermore, in the molding and positioning stage, traditional methods often employ simple supports or temporary binding to fix the transformer body. During molding, the body position is prone to shifting, resulting in uneven insulation distances between the primary winding and the secondary winding, as well as to ground. This leads to significant dispersion in excitation characteristics and poor batch consistency, severely hindering further improvements in the quality of voltage transformer products. Summary of the Invention
[0005] The purpose of this invention is to provide a voltage transformer body and its manufacturing method to solve the problem of deterioration of excitation characteristics caused by the iron core contacting epoxy resin or being subjected to casting and curing stress. At the same time, it solves the technical problems of unreliable body positioning, poor uniformity of insulation distance, and large dispersion of excitation characteristics of the product during the molding process.
[0006] To achieve the above objectives, the technical solution of this application is: a voltage transformer body, comprising: An insulating shell, hollow inside; An iron core is disposed in the inner cavity of the insulating shell, and silicone rubber is filled between the iron core and the inner wall of the insulating shell; The secondary winding is wound on the outside of the insulating shell; The primary winding is wound around the outside of the secondary winding; Secondary leads extend along the edge of the insulating shell; A shaped copper foil is attached to the outside of the secondary lead; The secondary terminal is located at the lower corner of the insulating shell, and the secondary lead is soldered to the secondary terminal. A semi-conductive wrinkled paper layer is partially wrapped around the outermost layer of the voltage transformer body.
[0007] In another embodiment of the present invention, the insulating shell is a gourd-shaped shell made of rigid insulating material, with its two lobes arranged symmetrically.
[0008] In another embodiment of the present invention, a grounding wire is connected to the corner of the iron core, and one end of the grounding wire is led out to the outside of the insulating shell and welded to the shaped copper foil, while the other end is locked to the embedded nut.
[0009] In another implementation of the present invention, the secondary lead is fixed with PVC tape and wrapped with a layer of A-10 insulating tape in half-overlap to the end of the secondary skeleton, with the outer side of the A-10 insulating tape tightly attached to the molded copper foil.
[0010] In another embodiment of the present invention, the silicone rubber is room temperature vulcanizing silicone rubber or addition-type high temperature vulcanizing silicone rubber, and the filling thickness of the silicone rubber is 1 to 3 mm.
[0011] In another embodiment of the invention, a pad is further included, which is disposed at the bottom of the insulating housing.
[0012] In another implementation of the present invention, the outer shielding copper foil of the primary winding is connected to a primary terminal via a conductive sheet, and the primary terminal is used to fix the primary winding during molding.
[0013] This invention also provides a method for manufacturing a voltage transformer body, comprising: Apply a layer of silicone rubber to the inner cavity of the insulating shell, weld a grounding wire at the corner of the iron core, install the iron core inside the insulating shell, close the insulating shell and lead out the grounding wire, squeeze out the excess silicone rubber by pressure, and let it cure naturally. The insulating shell is fixed, and a secondary winding is wound using a toroidal secondary winding machine. Then, it is moved to a parallel winding machine to wind the primary winding. The secondary lead is led out along the edge of the insulating shell, and the secondary lead is fixed with PVC tape. Then, a layer of A-10 insulating tape is half-overlapped and wrapped to the end of the secondary frame. A molded copper foil is attached to the outside. One end of the grounding wire is soldered to the molded copper foil. The secondary terminal is led out and soldered at the corner below the insulating shell. The outermost layer is half-overlapped with semi-conductive crepe paper to form the voltage transformer body. A pad is added below the voltage transformer body, making full contact with the bottom surface of the insulating housing. The distance between the primary winding and the secondary winding is adjusted. The primary winding is fixed by connecting the primary terminal. The lower part of the metal wire is wrapped with semi-conductive crepe paper and tightly attached to the semi-conductive crepe paper layer of the transformer body. The upper part of the metal wire passes through the mold cover plate and is twisted to the support plate. The metal wire is then tightened with bolts on the support plate, with the bottom of the bolts contacting the mold cover plate to fix the voltage transformer body. The secondary terminal is then connected, and the other end of the grounding wire is locked to the mounting insert. Finally, epoxy resin is used to cast the entire structure into one piece.
[0014] In another embodiment of the invention, the metal wire is also pulled out during demolding.
[0015] In another implementation of the present invention, an external force is applied before natural curing to drive the silicone rubber to flow, thereby achieving complete filling of the microscopic gap between the iron core and the insulating shell.
[0016] By adopting the above technical solution, the present invention can achieve the following technical effects: 1. This invention eliminates the need to add extra layers of iron core buffer wrapping, avoiding the increase in device size and reduction in design redundancy caused by increased wrapping, thus effectively reducing material costs.
[0017] 2. This invention fills the space between the iron core and the insulating shell with silicone rubber, which effectively prevents epoxy resin from penetrating the iron core during vacuum casting and also provides a good buffer against the volume shrinkage stress generated during casting and curing. This fundamentally solves the performance degradation problems caused by the iron core contacting resin or bearing stress in traditional processes, such as decreased permeability and increased loss. This makes the excitation characteristics of the voltage transformer stable and consistent, and the batch products have good consistency.
[0018] 3. This invention employs a molding and positioning method that combines wire hoisting with bolted support plates to ensure the transformer body maintains a precise position throughout the casting process. This guarantees the uniformity of the insulation distance between the primary winding and the secondary winding, as well as to ground, preventing a decrease in insulation performance due to body misalignment. Simultaneously, the thermal expansion and contraction of the filling resin will not adversely affect the core performance, significantly improving the product's insulation strength and service life. This effectively enhances the overall quality of the voltage transformer, ensuring its long-term safe and reliable operation in the power grid. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the voltage transformer body during molding. Figure 2 This is a schematic diagram of the voltage transformer body structure; Figure 3 This is a side view of the voltage transformer body; Figure 4 These are two views of the insulating shell; The numbers in the diagram are explained as follows: 1. Iron core; 2. Primary winding; 3. Secondary winding; 4. Insulating shell; 5. Conductive sheet; 6. Silicone rubber; 7. Voltage transformer body; 8. Spacer block; 9. Mold cover plate; 10. Metal wire; 11. Support plate; 12. Bolt; 13. Secondary lead wire; 14. Secondary terminal; 15. Primary terminal; 16. Molded copper foil. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0023] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0024] Example 1: like Figure 1-4 As shown, this embodiment provides a voltage transformer body, which includes the following structure: The insulating shell 4 is a gourd-shaped shell made of rigid insulating material. Its two symmetrical lobes are hollow inside, and its three sides are cylindrical, giving it an overall rectangular groove shape. The insulating shell 4 is integrally molded. The cylindrical shape facilitates the subsequent winding of the secondary winding; its bottom surface is in full contact with the pad block, ensuring a secure fixation of the device body.
[0025] The iron core 1 is a ring-shaped iron core, which is set in the inner cavity of the insulating shell 4. The space between the iron core 1 and the inner wall of the insulating shell 4 is filled with silicone rubber 6. The silicone rubber 6 is either room temperature vulcanizing silicone rubber or addition-curing high temperature vulcanizing silicone rubber, and the filling thickness is 1 to 3 mm. A grounding wire is welded at the corner of the iron core 1 and leads out to the outside of the insulating shell 4.
[0026] The secondary winding 3 is wound on the outside of the insulating shell 4, and the primary winding 2 is wound on the outside of the secondary winding 3. Before winding, the insulating shell 4 is fixed. The secondary winding 3 is wound using a toroidal secondary winding machine, and then the primary winding 2 is wound using a parallel winding machine. The primary winding 2 is connected to a primary terminal 15, which is used to fix the primary winding 2 during mold assembly.
[0027] Secondary lead 13 extends along the edge of insulating shell 4. Secondary lead 13 is fixed with PVC tape and wrapped with a layer of A-10 insulating tape in a half-overlap to the end of the secondary frame.
[0028] A shaped copper foil 16 is attached to the outside of the secondary lead 13, that is, the outer side of the A-10 insulating tape is tightly attached to the shaped copper foil 16. The grounding wire led out from the insulating shell 4 is welded from the iron core (1) and one end is welded to the shaped copper foil (16) through the middle gap outside the insulating shell (4). The secondary terminal 14 is located at the lower corner of the insulating shell 4, and the secondary lead 13 is welded to the secondary terminal 14.
[0029] A semi-conductive corrugated paper layer is disposed on the outermost layer of the voltage transformer body. Unlike the existing technology that deliberately increases the number and thickness of buffer wrapping layers to isolate the resin, this invention uses an insulating shell and silicone rubber to achieve physical isolation. The outer semi-conductive corrugated paper only serves a conventional shielding function and does not require additional thickening, thereby avoiding increased size and cost, while providing better shielding effect.
[0030] The pad 8 is located at the bottom of the insulating housing 4 and is used to support the voltage transformer body 7 and ensure its stability during molding.
[0031] In this embodiment, the silicone rubber 6 filling the space between the iron core 1 and the inner wall of the insulating shell 4 not only prevents the subsequent epoxy resin vacuum casting from penetrating the iron core 1, but also buffers the casting and curing stress, fundamentally solving the problem of performance degradation caused by the iron core contacting resin or bearing stress in traditional processes, thus making the excitation characteristics of the voltage transformer stable and consistent.
[0032] Example 2: This embodiment provides a method for manufacturing a voltage transformer body, including the following steps: An insulating shell 4 is formed by molding, and a layer of silicone rubber 6 is applied to the inner cavity of the insulating shell 4. The silicone rubber 6 can be any one of room temperature vulcanizing silicone rubber or addition-curing high-temperature vulcanizing silicone rubber, with a coating thickness of 1–3 mm, preferably 2–3 mm. A grounding wire is welded at the corner of the annular iron core 1. The iron core 1 is installed inside the insulating shell 4, the two halves of the insulating shell 4 are joined, and the grounding wire is led out. Excess silicone rubber is extruded using a small press at a pressure of 0.2–0.4 MPa, and then allowed to cure naturally. Before natural curing, an external force is applied to drive the silicone rubber 6 to flow, achieving complete filling of the microscopic gaps between the iron core 1 and the insulating shell 4. This ensures that the silicone rubber 6 remains well-adhered to the iron core 1 during shrinkage or stress release, preventing secondary loosening. This step, by applying an insulating shell 4 to the outside of the iron core 1 and filling it with silicone rubber 6, not only prevents subsequent epoxy resin vacuum casting from penetrating the iron core 1 but also buffers the casting and curing stress, fundamentally solving the performance degradation problem caused by the iron core contacting resin or bearing stress in traditional processes.
[0033] The insulating shell 4 is fixed to the winding machine, and the secondary winding 3 is wound using a toroidal secondary winding machine. Then, the primary winding 2 is wound using a parallel winding machine. After winding, the secondary lead 13 is led out along the edge of the insulating shell 4 and secured with PVC tape. A layer of A-10 insulating tape is then half-overlapped and wrapped to the end of the secondary frame. A shaped copper foil 16 is attached to the outside, and the grounding wire is soldered to the shaped copper foil 16. A secondary terminal 14 is led out and soldered at the lower corner of the insulating shell 4. The outermost layer is half-overlapped with semi-conductive crepe paper to form the voltage transformer body 7. This step does not add additional buffer wrapping, achieving better shielding while reducing costs.
[0034] During mold assembly, first place a pad 8 under the voltage transformer body 7, ensuring that the pad 8 is in full contact with the bottom surface of the insulating housing 4, and adjust the distance between the primary winding 2 and the secondary winding 3. Connect the primary terminal 15 to fix the primary winding 2. The lower part of the metal wire 10 is wrapped with semi-conductive corrugated paper, which is tightly adhered to the outermost layer of semi-conductive corrugated paper on the voltage transformer body 7; the upper part of the metal wire 10 passes through the mold cover plate 9 and is twisted to the support plate 11. The metal wire 10 is then tightened against the support plate 11 using bolts 12, with the bottom of the bolts 12 contacting the mold cover plate 9, thereby fixing the voltage transformer body 7 and ensuring its stability. Connect the secondary terminal 14, and lock the other end of the grounding wire to the mounting insert. Then, cast it into an integral structure using epoxy resin. When demolding, pull out the metal wire 10.
[0035] In this embodiment, the silicone rubber coating thickness is preferably 2 to 3 mm; the extrusion pressure is preferably 0.2 to 0.4 MPa; the silicone rubber can be any one of room temperature vulcanizing silicone rubber or addition-type high temperature vulcanizing silicone rubber.
[0036] The manufacturing method of this invention involves creating an insulating shell 4 and then applying silicone rubber 6 to the inner cavity of the insulating shell 4 to completely seal the iron core 1, preventing epoxy resin from entering the iron core 1. This solves the problems of stress on the iron core caused by traditional epoxy resin casting. Simultaneously, a molding and positioning method using metal wire 10 for hoisting and support plate 11 for tightening with bolts 12 ensures that the voltage transformer body 7 maintains a precise position throughout the casting process, guaranteeing the uniformity of the insulation distance between the primary winding 2 and the secondary winding 3, as well as to ground. The entire insulating shell manufacturing and molding hoisting operation is simple, the voltage transformer excitation characteristics are stable and consistent, and the product can operate safely.
[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A voltage transformer body, characterized in that, include: Insulating shell (4), which is hollow inside; An iron core (1) is disposed in the inner cavity of the insulating shell (4), and silicone rubber (6) is filled between the iron core (1) and the inner wall of the insulating shell (4). The secondary winding (3) is wound on the outside of the insulating shell (4); The primary winding (2) is wound around the outside of the secondary winding (3); Secondary lead (13) extends along the edge of the insulating shell (4); A shaped copper foil (16) is attached to the outside of the secondary lead (13); The secondary terminal (14) is located at the lower corner of the insulating shell (4), and the secondary lead is soldered to the secondary terminal (14); A semi-conductive wrinkled paper layer is partially wrapped around the outermost layer of the voltage transformer body.
2. The voltage transformer body according to claim 1, characterized in that, The insulating shell (4) is a gourd-shaped shell made of rigid insulating material, with its two symmetrical lobes.
3. The voltage transformer body according to claim 1, characterized in that, A grounding wire is connected to the corner of the iron core (1). The grounding wire is led out to the outside of the insulating shell (4), one end of which is welded to the shaped copper foil, and the other end is locked to the embedded nut.
4. The voltage transformer body according to claim 1, characterized in that, The secondary lead (13) is fixed with PVC tape and wrapped with a layer of A-10 insulating tape in half-overlap to the end of the secondary skeleton. The outer side of the A-10 insulating tape is tightly attached to the molded copper foil.
5. The voltage transformer body according to claim 1, characterized in that, The silicone rubber (6) is room temperature vulcanizing silicone rubber or addition-type high temperature vulcanizing silicone rubber, and the filling thickness of the silicone rubber (6) is 1 to 3 mm.
6. The voltage transformer body according to claim 1, characterized in that, It also includes a pad (8) which is disposed at the bottom of the insulating housing (4).
7. The voltage transformer body according to claim 1, characterized in that, The outer shielding copper foil of the primary winding (2) is connected to a primary terminal (15) via a conductive sheet (5). The primary terminal (15) is used to fix the primary winding (2) during molding.
8. A method for manufacturing a voltage transformer body, characterized in that, include: Apply a layer of silicone rubber (6) to the inner cavity of the insulating shell (4), weld a grounding wire at the corner of the iron core (1), install the iron core (1) inside the insulating shell (4), close the two halves of the insulating shell (4) and lead out the grounding wire, squeeze out the excess silicone rubber by pressure, and let it cure naturally. The insulating shell (4) is fixed, and a secondary winding (3) is wound using a ring secondary winding machine, and then moved to a parallel winding machine to wind a primary winding (2). The secondary lead (13) is led out along the edge of the insulating shell (4), and the secondary lead (13) is fixed with PVC tape. Then, a layer of A-10 insulating tape is wrapped halfway to the end of the secondary frame. A shaped copper foil is attached to the outside. One end of the grounding wire is welded to the shaped copper foil. The secondary terminal (14) is led out and welded at the corner below the insulating shell (4). The outermost layer is wrapped halfway with semi-conductive crepe paper to form the voltage body (7). A pad (8) is added below the voltage transformer body (7) to make full contact with the bottom surface of the insulating shell (4). The distance between the primary winding (2) and the secondary winding (3) is adjusted. The primary winding (2) is fixed by connecting the primary terminal (15). A metal wire (10) is passed through the mold cover plate (9) and tightened. The metal wire (10) is tightened by bolts (12) using the support plate (11) to fix the voltage transformer body (7). The secondary terminal (14) is connected. The other end of the grounding wire is locked to the mounting insert. Then, epoxy resin is used to cast it into an integral structure.
9. The method for manufacturing a voltage transformer body according to claim 8, characterized in that, It also includes pulling out the metal wire (10) during demolding.
10. A method for manufacturing a voltage transformer body according to claim 8, characterized in that, Before natural curing, an external force is applied to drive the silicone rubber (6) to flow, thereby completely filling the microscopic gap between the iron core (1) and the insulating shell (4).