A primary coil fixing structure based on a resin support

Abstract

This utility model discloses a primary coil fixing structure based on a resin bracket, relating to the field of voltage transformer technology. It includes a core clamp wrapped around the core, with an integrally formed support base with a support frame on its edge; a primary conductive sheet fixed to the bottom outer side of the primary coil, serving both conductive connection and structural support functions; and a resin bracket connected to the primary conductive sheet and the support frame of the core clamp via connectors to achieve positioning of the primary coil and the core. Metal inserts with threaded holes are pre-embedded at both ends of the resin bracket, allowing direct locking of the primary coil without the need for additional insulating partitions, significantly simplifying the assembly process. The epoxy resin and metal inserts are bonded using a vacuum casting process, ensuring zero air gap at the bonding surface and improving the product's partial discharge performance. The bracket is positioned below the primary coil, optimizing the size design and reducing the product's volume, making it suitable for compact switchgear and equipment miniaturization requirements.

Description

Technical Field

[0001] This utility model relates to the field of voltage transformer technology, specifically to a primary coil fixing structure based on a resin support. Background Technology

[0002] Voltage transformers are key devices in power systems that enable voltage measurement, protection, and control functions. Their core components include the primary coil, secondary coil, and iron core. In fully insulated voltage transformers, the way the primary coil is fixed directly affects the equipment's performance, size, and reliability.

[0003] Traditional fully insulated voltage transformers typically suspend their primary coils from the top or side of the core window using metal screws, metal plates, or metal frames. While this traditional method meets basic insulation requirements, it presents several problems in practical applications. 1. To ensure mechanical strength, metal hangers need to be designed with a sufficiently large cross-sectional area, which leads to an increase in the overall size of the instrument transformer, making it difficult to adapt to the development needs of compact switchgear and miniaturized power equipment.

[0004] 2. The thermal expansion coefficients of metals and insulating materials such as epoxy resins differ significantly. During temperature changes, shear stress is easily generated at the joint between the two, which may cause insulation cracking or coil displacement. At the same time, metal parts are prone to electric field concentration, increasing the risk of partial discharge.

[0005] 3. The installation and adjustment steps of traditional metal suspension structures are cumbersome, making it difficult to accurately control the insulation distance between the primary coil and the iron core and the secondary winding, and the assembly time is relatively long.

[0006] 4. Metal suspension fixing method is prone to air gaps or stress concentration during the casting process, which leads to an increase in the partial discharge of the product and a decrease in the pass rate; at the same time, the cost of metal materials is high, and rust prevention treatment and machining are required, which further increases the manufacturing cost.

[0007] To address the aforementioned technical challenges, a novel primary coil fixing structure is urgently needed to solve the problems of large size, complex assembly, poor insulation performance, and high cost. Utility Model Content

[0008] The purpose of this invention is to provide a primary coil fixing structure based on a resin bracket, achieving excellent insulation performance, convenient installation and adjustment, compact structure, and reduced cost.

[0009] To achieve the above objectives, this application proposes a primary coil fixing structure based on a resin support, comprising: The iron core clamp is wrapped around the iron core, and its edge is integrally formed with a support base with a support frame; The primary conductive sheet is fixed to the bottom outer side of the primary coil, serving the dual functions of conductive connection and structural support. The resin bracket is connected to the support frame of the primary conductive sheet and the iron core clamp respectively through connectors to realize the positioning of the primary coil and the iron core.

[0010] In one embodiment, the iron core clamp is provided with symmetrically distributed support seats, wherein a pair of diagonally opposite support seats are respectively provided with support frames, and countersunk holes are provided on the support frames.

[0011] In one embodiment, the countersunk hole is an elliptical countersunk hole, with an adjustment margin reserved along the major axis of the elliptical countersunk hole for adjusting the insulation distance between the primary coil and the iron core and the secondary coil.

[0012] In one embodiment, the connector is a cross-slot countersunk bolt, a fixing seat is provided on the primary conductive sheet, the cross-slot countersunk bolt is welded on the fixing seat, and the top of the cross-slot countersunk bolt does not exceed the plane of the fixing seat.

[0013] In one embodiment, the resin support is a cylindrical structure, and metal inserts are pre-embedded in the end face of the resin support. The metal inserts have threaded holes that are adapted to the connector.

[0014] In one embodiment, the outer peripheral wall of the metal insert is provided with an annular groove, which is combined with the resin support through a vacuum casting process, so that the resin material fills the annular groove to form a mechanical interlocking structure, and there is no air gap at the joint surface between the metal insert and the resin support.

[0015] In one embodiment, the resin support is made of glass fiber reinforced epoxy resin material.

[0016] In one embodiment, the primary conductive sheet is respectively disposed on both sides of the two sections of the primary coil, and the primary conductive sheet corresponds vertically to the support frame of the iron core clamp.

[0017] In one embodiment, the support base of the iron core clamp is provided with a fixing threaded hole for fixing the overall structure to the external mold base.

[0018] In one embodiment, the core clamp is fixed on one long side of the core, and the secondary winding is wound on the other long side of the core.

[0019] The advantages of the above technical solution adopted in this utility model compared with the prior art are: 1. In this application, the top of the cross-head countersunk bolt does not extend beyond the plane of the mounting base, which not only improves the aesthetics of the structure but, more importantly, avoids interference with the electric field distribution caused by the protruding bolt. Simultaneously, the resin bracket adopts a cylindrical, edgeless structure, which avoids the electric field concentration problem easily generated by metal components, effectively reducing the risk of partial discharge, adapting to high-voltage operating environments, and further enhancing insulation stability. Furthermore, the resin bracket is made of glass fiber reinforced epoxy resin, completely replacing traditional metal rods, eliminating floating potential, eddy current losses, and the risk of point discharge at the source, providing reliable protection for the safe operation of the equipment in high-voltage environments.

[0020] 2. This application employs an elliptical countersunk hole structure on the support frame of the diagonal support seat of the iron core clamp, with sufficient adjustment margin reserved in the long axis direction, allowing for precise adjustment of the insulation distance between the primary coil and the iron core and secondary winding. During actual installation, the bolts can be pre-tightened, and after the primary coil position is adjusted to the optimal state, the bolts can be fully tightened, significantly simplifying the assembly process and effectively saving assembly time.

[0021] 3. Compared with the traditional metal suspension fixing method, the resin bracket of this application is directly fixed to the bottom of the coil, eliminating the need to set a metal frame on the upper part and side wall of the primary coil, which significantly reduces the space occupied by the structure and thus effectively reduces the volume of the casting body, fully meeting the State Grid's technical requirements for the miniaturization and intensification of power equipment.

[0022] 4. In traditional metal suspension fixing methods, air gaps or stress concentrations easily form at the junction of the metal parts and the insulating material during the casting process, leading to increased partial discharge and a lower yield rate. In contrast, the resin support and epoxy casting material in this application have similar coefficients of thermal expansion, resulting in a tighter bond and preventing interface cracking after curing, effectively avoiding casting defects. Furthermore, the resin support is directly fixed to the bottom of the coil, eliminating the need for additional upper or sidewall metal supports. The casting body can closely conform to the outer contour of the coil, reducing unnecessary resin filling and significantly lowering epoxy resin usage. Moreover, the resin support can be mass-produced using compression molding, allowing multiple parts to be formed at once, resulting in high production efficiency. In addition, epoxy resin is cheaper than metal and requires no rust prevention treatment or complex machining, significantly reducing overall manufacturing costs. Attached Figure Description

[0023] Figure 1 Three-view diagram of a primary coil fixing structure based on a resin support; Figure 2 Here are the three views and enlarged views of the iron core clamp; Figure 3 This is a schematic diagram of the resin support structure. Figure 4 Three-view diagram of a primary conductive sheet; Wherein: 1 is the iron core; 2 is the iron core clamp; 21 is the support frame; 22 is the support base; 3 is the cross-slot countersunk bolt; 4 is the metal insert; 5 is the resin bracket; 6 is the primary conductive sheet; 7 is the primary coil; 8 is the secondary coil. Detailed Implementation

[0024] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0025] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0026] In the description of this application, it should be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] Please see Figure 1-4 This embodiment provides a primary coil fixing structure based on a resin bracket, including an iron core clamp, a primary conductive sheet, a resin bracket, and a cross-slot countersunk bolt. The structural and functional adaptation relationship of each component is as follows: The core clamp is made of steel plate through stamping and integral forming, forming a frame structure that wraps around the outer periphery of the core and makes close contact with it, ensuring stable installation and improving heat dissipation efficiency. Four rectangular, symmetrically distributed support seats are integrally formed along its edge, each with threaded holes for fixing the entire structure to the external mold base. A pair of diagonally opposite support seats have support frames with elliptical countersunk holes at their tops, allowing for precise adjustment of the insulation distance between the primary coil and the core, and between the primary and secondary coils.

[0029] The primary conductive sheet, made of copper sheet and tin-plated to improve conductivity and corrosion resistance, is fixed to the outer bottom of the primary coil by welding. It is positioned on the left and right sides of both sections of the primary coil, providing balanced support. A mounting base is welded to the primary conductive sheet, and countersunk bolts with Phillips head grooves are welded to the mounting base. After welding, the bolt tip must not exceed the plane of the mounting base to avoid the formation of a sharp point effect in the electric field. Simultaneously, the primary conductive sheet is also brazed to the leads of the primary coil, serving the dual functions of "conductive connection" and "structural support."

[0030] The resin support is made of glass fiber reinforced epoxy resin material through compression molding, forming a cylindrical structure without sharp edges. Its axial length is designed according to the voltage transformer specifications, combining high strength and high insulation performance. Furthermore, its coefficient of thermal expansion is close to that of epoxy castable, preventing interface cracking caused by temperature changes. Metal inserts are pre-embedded on both its upper and lower ends. The outer peripheral wall of the metal insert has an annular groove, which is bonded to the resin support through a vacuum casting process. The resin material fills the annular groove, forming a mechanical interlocking structure that ensures no air gaps at the joint surface, effectively reducing the risk of partial discharge. The metal insert has internal threads, with a thread specification compatible with Phillips head countersunk bolts, used to connect the resin support to the primary conductive sheet and support frame.

[0031] The components are assembled stably through a "layered positioning and step-by-step fixing" method, as detailed below: The upper end of the resin bracket is connected to the cross-slot countersunk bolt welded to the primary conductive sheet fixing seat through the internal thread of the top metal insert, so as to achieve rigid fixation with the primary coil. The lower end of the resin bracket: It is connected to the cross-slot countersunk bolt that passes through the elliptical countersunk hole of the support frame via the internal thread of the bottom metal insert, so as to achieve a detachable connection with the iron core clamp. The primary coil is suspended and fixed in the preset position of the iron core by the axial force of the cross-slot countersunk bolts. At the same time, the insulation properties of the resin bracket block the eddy current path, eliminating the risk of floating potential and tip discharge.

[0032] The assembly process of the primary coil fixing structure based on the resin bracket described above shall be carried out in the following steps to ensure that the position of each component is accurate and the connection is reliable: Assembly of iron core and iron core clamp: Align the iron core clamp with the outer circumference of the iron core so that the iron core clamp completely wraps around the iron core. Then fix the iron core clamp to one long side of the iron core by spot welding or positioning pins to ensure that there is no relative displacement between the iron core clamp and the iron core.

[0033] Secondary coil winding: Using the long side of the other side of the iron core as a reference, the secondary coil is evenly wound around the outside of the long side according to the designed number of turns. During the winding process, the winding tension is controlled to be uniform, ensuring that the coil is neatly arranged and tightly attached to the iron core, without looseness or deviation.

[0034] Primary coil winding: The primary coil is wound around the outside of the secondary coil, ensuring that the windings are neatly arranged, and the lead wire of the primary coil is reserved with the welding length to the primary conductive sheet.

[0035] Primary conductive sheet fixing: Weld the primary conductive sheet to the bottom outer side of the primary coil (the left and right sides of the two coil sections). Adjust the position simultaneously during welding to ensure that the cross-slot countersunk bolts on the primary conductive sheet fixing seat are coaxial with the elliptical countersunk holes of the diagonal support frame of the iron core clamp. Then, connect the primary conductive sheet to the lead wire of the primary coil by brazing to complete the construction of the conductive path.

[0036] Pre-connection of resin bracket: Align the upper end of the resin bracket with the cross-slot countersunk bolt on the primary conductive sheet fixing seat, rotate the resin bracket to engage the top metal insert with the bolt thread until it is tightened and fixed; then align the lower end of the resin bracket with the elliptical countersunk hole of the support frame, pass the cross-slot countersunk bolt through the countersunk hole and connect it with the bottom metal insert threadedly. At this time, only the bolt needs to be pre-tightened (not fully tightened) to leave room for position adjustment.

[0037] Insulation distance adjustment and final fixation: Slowly move the primary coil along the long axis of the elliptical countersunk hole of the support frame, and monitor the distance between the primary coil and the iron core and the secondary coil with a measuring tool (such as a vernier caliper) until the designed insulation distance is reached; after confirming that the position is correct, fully tighten the cross-slot countersunk bolts on the support frame to achieve rigid fixation of the resin bracket and the support frame.

[0038] Fixing the entire structure to the mold: Align the positioning holes of the external mold base with the fixing threaded holes of the four support seats of the iron core clamp, and use bolts to fix the entire structure to the mold base through the threaded holes to complete the entire assembly process.

[0039] The aforementioned primary coil fixing method based on resin brackets has many advantages, such as convenient installation, stable insulation, compact structure, and reduced cost. It provides an innovative solution for the design of fully insulated voltage transformers and can be widely used in the State Grid's power transmission and distribution network, thereby improving the design and manufacturing level of fully insulated voltage transformers.

[0040] 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 primary coil fixing structure based on a resin support, characterized in that, include: The iron core clamp is wrapped around the iron core, and its edge is integrally formed with a support base with a support frame; The primary conductive sheet is fixed to the bottom outer side of the primary coil, serving the dual functions of conductive connection and structural support. The resin bracket is connected to the support frame of the primary conductive sheet and the iron core clamp respectively through connectors to realize the positioning of the primary coil and the iron core.

2. The resin support-based one-coil fixing structure according to claim 1, wherein The iron core clamp is provided with symmetrically distributed support seats, and a pair of diagonally opposite support seats are respectively provided with support frames, and countersunk holes are opened on the support frames.

3. The one-time coil fixation structure based on a resin support according to claim 2, characterized in that, The countersunk hole is an elliptical countersunk hole, with an adjustment margin reserved along its major axis to adjust the insulation distance between the primary coil and the iron core, and between the secondary coil and the iron core.

4. The resin support-based one-coil fixing structure according to claim 1, wherein The connector is a cross-slot countersunk bolt. A fixing seat is provided on the primary conductive sheet, and a cross-slot countersunk bolt is welded on the fixing seat. The top of the cross-slot countersunk bolt does not exceed the plane of the fixing seat.

5. The one-time coil fixing structure based on a resin support according to claim 1 or 4, characterized in that, The resin support is a cylindrical structure, and metal inserts are pre-embedded in the end face of the resin support. The metal inserts have threaded holes that are adapted to the connectors.

6. The one-time coil fixation structure based on a resin support according to claim 5, characterized in that, The outer peripheral wall of the metal insert is provided with an annular groove. It is combined with the resin support through a vacuum casting process, so that the resin material fills the annular groove to form a mechanical interlocking structure, and there is no air gap at the joint surface between the metal insert and the resin support.

7. The one-time coil fixing structure based on a resin support according to claim 1, characterized by, The resin support is made of glass fiber reinforced epoxy resin material.

8. The primary coil fixing structure based on a resin support according to claim 1, characterized in that, The primary conductive plates are respectively disposed on both sides of the two sections of the primary coil, and the primary conductive plates are vertically aligned with the support frame of the iron core clamp.

9. The one-time coil fixation structure based on a resin support according to claim 1, characterized in that, The iron core clamp has a fixed threaded hole on its support base for fixing the overall structure to the external mold base.

10. The resin support-based one-coil fixing structure according to claim 1, wherein The core clamp is fixed on one long side of the core, and the secondary winding is wound on the other long side of the core.

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