Cylindrical skeleton of primary coil of voltage transformer

Abstract

The utility model relates to a mutual inductor, in particular to a primary coil cylindrical framework of a voltage transformer, and solves the problem of structural design of the mutual inductor. The primary coil cylindrical framework of the voltage transformer comprises a cylindrical barrel, a notch is formed in the barrel in the radial direction, positioning grooves are formed in the sides, symmetrical to the circle center of the barrel, of the notch, clamping parts matched with the notch in an embedded mode are arranged on the opposite side faces of the notch, and the barrel is formed through injection molding of alloy plastics. The cylinder body is formed by alloy plastic particles through hot melting injection molding, and the tolerance of the inner diameter, the outer diameter and the height of the cylinder body is smaller than or equal to + / -0.5 mm. The injection molding process has the advantages of high efficiency, realization of automatic mass production, high dimensional precision, round cylinder opening, good insulation performance, flame retardance, matching of a softening point and an epoxy resin curing temperature, and effective bonding with an epoxy resin cured material. And the phenomenon that the partial discharge capacity of the high-voltage side of the voltage transformer exceeds the standard can be improved and solved by matching with semiconductor crepe paper or semiconductor cloth tapes wrapped outside the inner and outer diameters.

Description

Technical Field

[0001] This utility model relates to a current transformer, and more particularly to a cylindrical frame for the primary coil of a voltage transformer. Background Technology

[0002] Voltage transformers, similar to transformers, are instruments used to transform voltage. However, transformers transform voltage to facilitate the transmission of electrical energy, therefore their capacity is very large, typically measured in kilovolt-amperes (kVA) or megavolt-amperes (MVA). Voltage transformers, on the other hand, transform voltage primarily to power measuring instruments and relay protection devices, used to measure line voltage, power, and electrical energy, or to protect valuable equipment, motors, and transformers in the event of a line fault. Therefore, voltage transformers have a very small capacity, generally only a few volt-amperes or tens of volt-amperes, with a maximum not exceeding one thousand volt-amperes. This entry introduces its basic structure, working principle, main types, wiring methods, precautions, abnormalities and handling, and ferroresonance, etc.

[0003] Currently, the primary coil bobbins of voltage transformers are primarily made of epoxy resin or do not contain resin. They are formed by winding fiberglass cloth and then curing with epoxy resin or unsaturated resin. Due to the high rigidity of the material and the sharp edges resulting from lathe cutting at both ends, the primary coils directly wound into shape are prone to stress and micro-cracks during the curing process after vacuum casting. Furthermore, the high rigidity and significant difference in shrinkage rate between the coil and the transformer's casting and curing system lead to interfacial micro-cracks in the bonding. Additionally, grinding and sandblasting increase costs. Utility Model Content

[0004] To address the shortcomings of existing technologies, this utility model provides a cylindrical frame for the primary coil of a voltage transformer.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a cylindrical frame for the primary coil of a voltage transformer, comprising a cylindrical body, wherein the cylindrical body has a notch in the radial direction, and the cylindrical body has a positioning groove on the symmetrical side of the notch relative to the center of the cylindrical body, and the notch has a locking part on the opposite side, wherein the cylindrical body is injection molded by alloy plastic.

[0006] The cylinder is formed by hot-melt injection molding of alloy plastic particles, and the tolerance of the inner and outer diameter and height of the cylinder is ≤ ±0.5mm.

[0007] The positioning groove is located on the axial end face of the cylinder.

[0008] The positioning groove is provided on each of the two end faces of the cylinder in the axial direction.

[0009] The positioning groove forms a through slot in the radial direction of the cylinder.

[0010] The engaging part includes engaging grooves and engaging blocks respectively provided on the two side walls of the notch.

[0011] The projection of the locking block along its length is an isosceles trapezoid, and the shape and size of the locking groove are adapted to the locking block.

[0012] The two side walls of the notch are provided with a surrounding contact surface at the outer edge of the engaging part.

[0013] The beneficial effects of this utility model are as follows: The injection molding process of the cylindrical skeleton of the primary coil of the voltage transformer provided by this utility model is highly efficient, realizes automated mass production, has high dimensional accuracy, a round cylinder opening, good insulation performance, flame retardancy, and its softening point matches the curing temperature of epoxy resin, which can effectively bond with the cured epoxy resin. When combined with the outer coating of semiconductor crepe paper or semiconductor tape on the inner and outer diameters, it can improve and solve the problem of excessive partial discharge on the high-voltage side of the voltage transformer. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model;

[0015] Figure 2 This is a schematic diagram of the structure of this utility model;

[0016] Figure 3 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0017] like Figures 1-3 As shown, the primary coil cylindrical frame of the voltage transformer includes a cylindrical body 1. The cylindrical body 1 has a notch 2 in the radial direction. A positioning groove 3 is provided on the symmetrical side of the notch 2 relative to the center of the cylindrical body 1. The notch 2 has interlocking engaging parts 4 on opposite sides. The cylindrical body 1 is injection molded from alloy plastic. The notch 2 is designed similarly to an expansion joint, providing space for stress expansion and release. The cylindrical body 1 helps to evenly offset and disperse stress, and the notch 2 design significantly improves the micro-crack phenomenon during subsequent casting and curing. The positioning groove 3 is designed for winding positioning, and it also corresponds to the location of the notch 2, which is also a stress concentration point. Winding can also alleviate and release stress to a certain extent, improving structural stability. The engaging part 4 is designed to avoid large spatial redundancy or contraction during stress expansion and contraction, and is designed to move within a small range. That is, the engaging part 4 has a small stroke range of movement to adapt to stress changes.

[0018] The cylinder 1 is formed by hot-melt injection molding of alloy plastic particles, and the tolerances of the inner and outer diameters and height of the cylinder 1 are ≤ ±0.5mm. This improves the uniformity of molding and the controllability of stress changes, thereby adapting to the structural design. The positioning groove 3 is located on the axial end face of the cylinder 1, which facilitates winding restriction and positioning. There is one positioning groove 3 on each of the two axial end faces of the cylinder 1, so that the axial direction can also achieve a balanced effect. The positioning groove 3 forms a through groove in the radial direction of the cylinder 1, which is equivalent to opening a release port at the stress concentration point, where the stress direction cancels or weakens each other. The manufacturing requirements for the coil frame are a heat deformation temperature of not less than 125℃, a breakdown strength of not less than 40kV / mm, and an inner and outer diameter and height tolerance of less than or equal to ±0.5.

[0019] The engaging portion 4 includes engaging grooves 5 and engaging blocks 6 respectively disposed on the two side walls of the notch 2. This is one embodiment, with a simple structure and convenient injection molding. The projection of the engaging block 6 in the length direction is an isosceles trapezoid, and the shape and size of the engaging groove 5 are suitable for the engaging block 6. The isosceles trapezoid facilitates slow and accurate engagement during assembly or processing. The two side walls of the notch 2 are provided with circumferential contact surfaces 7 at the outer edge of the engaging portion 4, which can form a relatively closed and sealed structure in the fully engaged state, achieving the effect of a labyrinth seal. A labyrinth seal is a process in which the medium achieves throttling and sealing through narrow and tortuous channels.

[0020] Processing Flow Overview: Preliminary Preparation: Dry the alloy plastic granules, clean the barrel, and install the injection mold. Feeding: Quantitatively proportioned plastic components are added to the hopper. This quantitative (volume-controlled) feeding ensures uniform plasticization, guaranteeing stable operation and high-quality skeleton products. Axial Plasticization: Within the injection molding machine barrel, the plastic granules undergo heating, compaction, and mixing, transforming from granular solids into a continuous, homogenized melt. Injection: The plunger or screw, starting from the metering position within the barrel, applies high pressure through the injection cylinder and piston, rapidly feeding the plasticized melt through the nozzle at the front of the barrel and the gating system in the mold into the closed mold cavity. Holding Pressure: After filling, maintain pressure on the molten plastic for a certain period. Cooling: After freezing, the plastic is kept in the mold cavity for a certain cooling time. Demolding: Once the plastic part has cooled to a certain temperature, the mold is opened, and the ejector mechanism pushes the part out of the mold. Product Molding and Packaging: Remove burrs, flash, and excess material, then inspect the product. Once qualified, it is packaged.

[0021] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "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 utility model 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 utility model. At the same time, the basic principles, main features, and advantages of this utility model have been shown and described above, which should be understood by those skilled in the art.

Claims

1. A cylindrical frame for the primary coil of a voltage transformer, characterized in that, The device includes a cylindrical body with a notch in the radial direction. The body also has a positioning groove on the symmetrical side of the notch relative to the center of the body. The notch has a locking part on the opposite side. The body is injection molded from alloy plastic.

2. The cylindrical frame of the primary coil of the voltage transformer as described in claim 1, characterized in that, The cylinder is formed by hot-melt injection molding of alloy plastic particles, and the tolerance of the inner and outer diameter and height of the cylinder is ≤ ±0.5mm.

3. The cylindrical frame of the primary coil of the voltage transformer as described in claim 1 or 2, characterized in that, The positioning groove is located on the axial end face of the cylinder.

4. The cylindrical frame of the primary coil of the voltage transformer as described in claim 3, characterized in that, The positioning groove is provided on each of the two end faces of the cylinder in the axial direction.

5. The cylindrical frame of the primary coil of the voltage transformer as described in claim 4, characterized in that, The positioning groove forms a through slot in the radial direction of the cylinder.

6. The cylindrical frame of the primary coil of the voltage transformer as described in claim 1, characterized in that, The engaging part includes engaging grooves and engaging blocks respectively provided on the two side walls of the notch.

7. The cylindrical frame of the primary coil of the voltage transformer as described in claim 6, characterized in that, The projection of the locking block along its length is an isosceles trapezoid, and the shape and size of the locking groove are adapted to the locking block.

8. The cylindrical frame of the primary coil of the voltage transformer as described in claim 7, characterized in that, The two side walls of the notch are provided with a surrounding contact surface at the outer edge of the engaging part.

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