A three-phase voltage transformer

Abstract

This utility model provides a three-phase voltage transformer, relating to the technical field of high-voltage transformers in power systems. It includes a main insulator, formed by vacuum casting with epoxy resin; European-style C-shaped connectors distributed on the top of the main insulator; high-voltage fuses correspondingly disposed inside each European-style C-shaped connector; and a horizontally arranged resin-coil integrated structure embedded inside the main insulator. The resin-coil integrated structure specifically includes: a core clamp wrapped around the outside of the core, with an integrally formed support base with a support frame on its edge; a primary conductive sheet fixed to the bottom outside of the primary coil, serving both conductive connection and structural support functions; and a resin bracket connected to the support frame of the primary conductive sheet and the core clamp via connectors, thereby achieving precise positioning of the primary coil and the core. This application has advantages in terms of convenient installation, stable insulation, compact structure, and reduced cost.

Description

Technical Field

[0001] This utility model relates to the technical field of high-voltage transformers in power systems, specifically to a three-phase voltage transformer. Background Technology

[0002] As the power system rapidly develops towards "high voltage, large capacity, and small size," three-phase voltage transformers, as core primary equipment for power metering, relay protection, and condition monitoring, are subject to higher requirements in terms of safety, reliability, insulation performance, and structural compactness. The industry has clearly defined new requirements for three-phase voltage transformers as "high reliability and small size."

[0003] In the current technological system, the primary coil fixing methods of traditional three-phase voltage transformers are mainly divided into two categories, both of which have significant drawbacks: Metal bracket + insulating partition: This structure is prone to electric field concentration, resulting in high partial discharge; metal parts are prone to corrosion during long-term operation, which can lead to mechanical loosening and affect equipment stability; at the same time, a large creepage distance is required to meet insulation requirements, making the overall product bulky and difficult to adapt to installation scenarios with limited space.

[0004] Ceramic support pillars + binding method: Ceramic components are inherently brittle and easily damaged by external impacts during transportation, installation and operation; moreover, this structure still relies on oil or sulfur hexafluoride as the insulating medium, which not only poses a risk of medium leakage, but also causes the greenhouse effect due to sulfur hexafluoride emissions, which does not meet the green requirements of modern environmental protection regulations for power equipment.

[0005] The two types of fixing schemes mentioned above are difficult to meet the requirements of modern power grids for equipment miniaturization, high reliability and green manufacturing. Therefore, there is an urgent need for an innovative primary coil fixing structure to solve the pain points of traditional technology. Utility Model Content

[0006] The purpose of this utility model is to provide a three-phase voltage transformer to solve the problems of large size, weak insulation, complex assembly and poor environmental performance of traditional voltage transformers, so as to achieve miniaturization, high reliability and low cost of equipment production.

[0007] To achieve the above objectives, this application proposes a three-phase voltage transformer, comprising: The main insulator is formed by vacuum casting of epoxy resin. European-style C-shaped connectors are located on the top of the main insulator; High-voltage fuses are installed inside each European-style C-connector; A horizontally arranged resin and coil integrated structure is embedded inside the main insulator; the resin and coil integrated structure specifically includes: The iron core clamp is wrapped around the outside of 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, thereby achieving precise positioning of the primary coil and the iron core.

[0008] In one embodiment, the main insulator has a cuboid structure, with a cuboid resin-coated iron core on its front and back sides. The top of the cuboid resin core has multiple curved surfaces symmetrically arranged on the front and back, and the bottom is flush with the main insulator.

[0009] 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.

[0010] 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.

[0011] 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.

[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 European-style C-shaped connector has a fuse cavity in the horizontal direction; a spring, a high-voltage fuse, and a bolt sleeve are arranged sequentially in the fuse cavity.

[0014] In one embodiment, the inner wall of the fuse cavity is provided with a high-voltage shielding mesh, a fuse shielding mesh and a ground shielding mesh in sequence from the inside to the outside; the high-voltage shielding mesh and the fuse shielding mesh are horizontally fitted inside and outside the fuse cavity, with gaps between them.

[0015] In one embodiment, the resin and coil integrated structure consists of two parts, arranged horizontally, and uses a VV wiring method.

[0016] In one embodiment, the main insulator has continuous inward concave shapes on both sides and a secondary wiring groove in front.

[0017] The advantages of the above technical solution adopted in this utility model compared with the prior art are: 1. The main insulator of this utility model is made by vacuum casting of epoxy resin, and the internal structure of resin and coil is integrated, which greatly optimizes the insulation performance. At the same time, the resin support has mechanical strength and can firmly fix the primary coil, eliminating the need for traditional binding or gluing methods. This effectively avoids the risk of coil loosening under temperature changes or vibration, and ensures the long-term stability and reliability of the overall structure.

[0018] 2. This utility model features an elliptical countersunk hole structure on the support frame of the diagonal fixing seat of the iron core clamp, with sufficient adjustment margin reserved in the direction of the major axis of the ellipse. During the assembly of the device body, the insulation distance between the primary coil and the iron core and the secondary winding can be precisely adjusted through this structure. During installation, the bolts can be pre-tightened first, and then fully tightened and fixed after the position of the primary coil is adjusted to the optimal state, which greatly shortens the assembly time and improves the installation efficiency.

[0019] 3. Compared with the traditional metal suspension fixing method, the resin bracket of this utility model is directly fixed to the bottom of the coil, eliminating the need for a metal frame on the upper part and side wall of the coil, which significantly reduces space occupation and effectively reduces the volume of the casting body, fully meeting the State Grid's technical requirements for the miniaturization and intensification of power equipment.

[0020] 4. Traditional metal suspension fixing methods are prone to air gaps or stress concentrations during the casting process due to structural compatibility issues, leading to increased partial discharge and decreased yield. In this invention, the resin support and epoxy casting material 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, thus saving material costs. The resin support can also be molded using a compression molding process, allowing for the simultaneous molding of multiple parts, resulting in high production efficiency. Additionally, epoxy resin is cheaper than metal materials and requires no rust prevention treatment or machining, further reducing manufacturing costs.

[0021] 5. This utility model incorporates a high-voltage fuse connected in series at the high-voltage end of the instrument transformer. When a short circuit occurs inside the instrument transformer, an overload occurs, or a power grid fault occurs, the fuse can quickly melt and disconnect the fault current in a timely manner, preventing the accident from escalating further. This design effectively isolates faulty equipment, prevents high voltage from entering the secondary circuit, effectively protects the safety of operators and the stable operation of measurement and protection devices, and significantly improves the operational reliability of the entire power system. Attached Figure Description

[0022] Figure 1 Three-phase voltage transformer three-view diagram; Figure 2 for Figure 1BB cross-sectional view; Figure 3 for Figure 1 AA section view; Figure 4 These are the three views of the iron core clamp. Figure 5 This is a schematic diagram of the resin support structure. Figure 6 These are three views of a primary conductive sheet.

[0023] Among them: 1 is the iron core; 2 is the iron core clamp; 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; 9 is the main insulator; 10 is the bolt sleeve; 11 is the curved surface; 12 is the European C-shaped connector; 13 is the high-voltage fuse; 14 is the high-voltage shielding mesh; 15 is the ground shielding mesh; 16 is the fuse shielding mesh; 17 is the spring; 18 is the base plate. 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] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0027] 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.

[0028] 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.

[0029] like Figure 1-6 As shown, this utility model discloses a three-phase voltage transformer, including a mounting base plate 18 and a main insulator 9 disposed on the mounting base plate 18. The main insulator 9 is made of epoxy resin by vacuum casting and has a cuboid structure. It has European C-shaped connectors 12 at its upper left corner, middle and upper right corner, and a high-voltage fuse 13 is disposed in each European C-shaped connector 12.

[0030] The main insulator 9 internally houses two horizontally arranged resin-coil integrated structures, using a VV wiring method. The resin-coil integrated structure specifically includes: The iron core clamp 2 is wrapped around the outside of the iron core 1, and its edge is integrally formed with a support base with a support frame; The primary conductive sheet 6 is fixed to the bottom outer side of the primary coil 7, and has the dual functions of conductive connection and structural support. The resin bracket 5 is connected to the support frame of the primary conductive sheet 6 and the iron core clamp 2 through connectors, thereby achieving precise positioning of the primary coil 7 and the iron core 1.

[0031] The main insulator 9 has rectangular resin-coated iron cores 1 on both its front and rear sides. The tops of the two rectangular resin cores are symmetrically decorated with multiple curved surfaces, and their bottoms are flush with the main insulator 9. The main insulator 9 has continuous inward concave shapes on both sides, and a secondary wiring groove is located in the lower middle of the front. These structural designs can effectively reduce the volume of the main insulator and the amount of resin used.

[0032] The iron core clamp 2 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. The countersunk holes are elliptical countersunk holes, and the major axis of the elliptical countersunk holes is reserved for adjustment, which is used to adjust the insulation distance between the primary coil 7 and the iron core 1 and the secondary coil 8.

[0033] The connector is a cross-slot countersunk bolt 3. A fixing seat is provided on the primary conductive sheet 6, 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 to avoid affecting the electric field distribution. The resin support 5 is a cylindrical structure. Metal inserts 4 are pre-embedded in the end face of the resin support 5. The metal inserts 4 have threaded holes. The internal thread of the top metal insert is threaded to the cross-slot countersunk bolt to achieve rigid fixation with the primary coil. The internal thread of the bottom metal insert is threaded to the cross-slot countersunk bolt that passes through the elliptical countersunk hole of the support frame to achieve detachable connection with the iron core clamp.

[0034] The European-style C-shaped connector 12 has a fuse cavity in the horizontal direction; a spring 17, a high-voltage fuse 13, and a bolt sleeve 10 are arranged sequentially inside the fuse cavity. The inner wall of the fuse cavity is provided with a high-voltage shielding mesh 14, a fuse shielding mesh 16, and a ground shielding mesh 15 from the inside to the outside; the high-voltage shielding mesh 14 and the fuse shielding mesh 16 are horizontally fitted inside and outside the fuse cavity with gaps between them, which can completely shield the high and low voltage electric fields, making the electric field inside and outside the product uniform, reducing partial discharge, and ensuring safe and reliable operation.

[0035] An installation insert is provided below the main insulator 9, which is fixed to the base plate 18 by bolts. This optimized structural design facilitates the installation and fixation of the current transformer.

[0036] In this embodiment, the fabrication process of the above-mentioned three-phase voltage transformer is as follows: Align the iron core clamp with the outer periphery 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. 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. 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. The primary conductive sheet is welded to the bottom outer side of the primary coil (the left and right sides of the two coil sections). During welding, the position is adjusted simultaneously to ensure that the cross-slot countersunk bolts on the primary conductive sheet mounting base are coaxial with the elliptical countersunk holes of the diagonal support frame of the iron core clamp. Then, the primary conductive sheet is connected to the lead wire of the primary coil by brazing to complete the construction of the conductive path. Align the upper end of the resin bracket with the cross-slot countersunk bolt on the primary conductive sheet mounting base, 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. 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 form an integrated resin and coil structure; The two resin and coil integrated structures are arranged horizontally. The entire structure is securely installed on the mold base by means of the threaded holes of the four fixing seats on the iron core clamp 2. Then, the epoxy resin is poured using the VV wiring method to finally form the main insulator 9. Inside the fuse cavity of the European C-type connector 12, the assembly is completed in the order of spring 17, high-voltage fuse 13, and bolt sleeve 10. By using the pre-installed mounting insert on the base plate below the main insulator 9, the main insulator 9 and the mounting base plate 18 can be bolted together to complete the overall fixed assembly of the current transformer.

[0037] In use, first, according to the phase sequence distance, use the mounting plate 18 of the voltage transformer to fix the voltage transformer on the switch cabinet. Then, connect the primary terminals of the product in parallel to the high-voltage side of the line. Finally, connect the secondary cables on the low-voltage side to the secondary terminals to complete the assembly of the fully insulated voltage transformer. When there is an internal short circuit, overload, or power grid fault in the transformer, the high-voltage fuse 13 will quickly melt and cut off the fault current, preventing high voltage from entering the secondary circuit and protecting the safety of personnel and measuring and protection devices.

[0038] The three-phase voltage transformer based on a resin support primary coil provided by this utility model has many advantages such as convenient installation, stable insulation, compact structure, and reduced cost. It provides an innovative design solution for the design of three-phase voltage transformers and can be widely used in the power transmission and distribution network of the State Grid, thereby improving the design and manufacturing level of three-phase voltage transformers.

[0039] 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 three-phase voltage transformer, characterized in that, include: The main insulator is formed by vacuum casting of epoxy resin. European-style C-shaped connectors are located on the top of the main insulator; High-voltage fuses are installed inside each European-style C-connector; A horizontally arranged resin and coil integrated structure is embedded inside the main insulator; the resin and coil integrated structure specifically includes: The iron core clamp is wrapped around the outside of 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, thereby achieving precise positioning of the primary coil and the iron core.

2. A three-phase voltage transformer according to claim 1, characterised in that The main insulator has a cuboid structure, with a cuboid resin-coated iron core on its front and back sides. The top of the cuboid resin core has multiple curved surfaces symmetrically arranged on the front and back, and the bottom is flush with the main insulator.

3. A three-phase voltage transformer according to claim 1, characterised in that 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.

4. A three-phase voltage transformer according to claim 3, characterised 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.

5. A three-phase voltage transformer according to claim 3, characterised 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. A three-phase voltage transformer according to claim 1 or 5, characterised in that 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.

7. A three-phase voltage transformer according to claim 1, characterised in that The European-style C-shaped connector has a fuse cavity in the horizontal direction; a spring, a high-voltage fuse, and a bolt sleeve are arranged in sequence inside the fuse cavity.

8. A three-phase voltage transformer according to claim 7, characterised in that The inner wall of the fuse cavity is provided with a high-voltage shielding mesh, a fuse shielding mesh and a ground shielding mesh in sequence from the inside to the outside; the high-voltage shielding mesh and the fuse shielding mesh are horizontally fitted inside and outside the fuse cavity, with gaps between them.

9. A three-phase voltage transformer according to claim 1, characterised in that The resin and coil integrated structure consists of two parts, arranged horizontally, and uses a VV wiring method.

10. A three-phase voltage transformer according to claim 1, characterised in that The main insulator has continuous inward concave shapes on both sides and a secondary wiring groove in front.

Images