A split-type three-phase AC electronic voltage transformer

Abstract

This invention discloses a split-type three-phase AC electronic voltage transformer, comprising three insulators. The primary high-voltage capacitor, primary high-voltage terminal, secondary terminal a, secondary terminal n, and low-voltage metal shielding ring within each insulator are vacuum-cast with epoxy resin. One end of the low-voltage cable is sequentially connected back to the other end of the low-voltage cable via the secondary terminal n, secondary capacitor, and secondary terminal a within the insulator. Polyurethane resin is used for secondary encapsulation of the secondary capacitor, low-voltage cable, secondary terminal a, and secondary terminal n through a potting port on the insulator base plate. The primary high-voltage terminal plugs of the three insulators are inserted into an interface at the three-phase cable terminal. After voltage division by the primary and secondary capacitors, the required three-phase voltage signals are obtained. This application allows for simultaneous use of all three transformers to measure three-phase voltage, or for single-phase use to measure single-phase voltage. It features high withstand voltage, maintenance-free operation, long service life, small size, convenient wiring, low partial discharge, and high measurement accuracy.

Description

Technical Field

[0001] This invention relates to high-voltage measurement or relay protection equipment for power systems, specifically to a split-type three-phase AC electronic voltage transformer. Background Technology

[0002] Electronic voltage transformers are one of the key devices in modern power systems that meet the development trends of high-voltage electrical equipment towards intelligence, modularity, miniaturization, multi-functionality, and maintenance-free operation. They are also necessary for the automation and digitalization of power systems. Modern microcomputer-based integrated measurement and protection devices and instruments no longer require transformers to provide energy for operation. They only need the transformers to collect and transmit primary voltage information completely, promptly, and accurately. A voltage signal of a few volts and minimal power consumption are sufficient to meet interface requirements.

[0003] Traditional electric field voltage transformers are difficult to meet the requirements of computer technology for complete digital processing of voltage information, making it difficult to achieve online monitoring of changes in electrical parameters in the power grid and hindering the development of power system automation to a higher level. In addition, traditional electronic voltage transformers use resistive voltage division, which is greatly affected by ambient temperature, and the measurement accuracy is affected by changes in the length of the secondary cable. Alternatively, they use capacitive voltage division, which has small capacitance, low measurement accuracy, poor anti-interference ability, and is greatly affected by changes in the length of the secondary cable. Furthermore, the three phases are installed in a relatively fixed position on a base plate, resulting in large installation space, low withstand voltage rating, unsuitability for harsh environments, easy breakdown, and short service life. Summary of the Invention

[0004] The purpose of this invention is to provide a novel split-type three-phase AC electronic voltage transformer that is vacuum cast with epoxy resin, has a small installation space, can be positioned arbitrarily, has a high withstand voltage rating, low partial discharge, stable error performance, adapts to harsh environments, and has a long service life.

[0005] To achieve the above objectives, this application proposes a split-type three-phase AC electronic voltage transformer, comprising three insulators. In each insulator, the primary high-voltage capacitor, primary high-voltage terminal, secondary terminal a, secondary terminal n, and low-voltage metal shielding ring are vacuum-cast with epoxy resin. One end of the low-voltage cable is sequentially connected back to the other end of the low-voltage cable through the secondary terminal n, secondary capacitor, and secondary terminal a in the insulator. Polyurethane resin is used to perform secondary encapsulation of the secondary capacitor, low-voltage cable, secondary terminal a, and secondary terminal n through the injection port on the base plate of the insulator, ensuring that the secondary capacitor is not affected by the vibration of the low-voltage cable, thus improving the stability and accuracy of the equipment. The plug portion of the primary high-voltage terminal of each of the three insulators is inserted into an interface at the end of the three-phase cable. After voltage division by the primary high-voltage capacitor and the secondary capacitor, the required three-phase voltage signals are obtained respectively.

[0006] Furthermore, the primary high-voltage terminal plug part is a conical head with internal threads, facilitating threaded connection with the matching cable interface, enabling good adaptation to cable installation, and enhancing sealing performance and withstand voltage level.

[0007] Furthermore, the primary high-voltage capacitor is made of high-voltage-resistant ceramic material, suitable for harsh environments and having a long service life. The primary high-voltage capacitor is located below the primary high-voltage terminal and above the secondary terminal n and secondary terminal a. The secondary capacitor is made of ceramic material.

[0008] Furthermore, the low-voltage metal shielding ring is arranged between the primary high-voltage capacitor and the primary high-voltage terminal and is at the transition from the conical head to the cylinder. The connecting wire between the primary high-voltage capacitor and the primary high-voltage terminal passes through the center of the low-voltage metal shielding ring, making the internal and external electric fields more uniform, improving the partial discharge level of the mutual inductor, and ensuring safe and stable operation.

[0009] Even further, the low-voltage metal shielding ring consists of a circular metal shielding net and a low-voltage metal shielding ring insert welded by metal wires and is sprayed with a layer of semi-conductive paint on the outside to enhance the shielding effect.

[0010] Even further, a layer of semi-conductive paint is sprayed on the outer surface of the insulator from the root of the conical head to the connection with the bottom plate to shield the high-voltage electric field outside and ensure stable error. This layer of semi-conductive paint contacts the end faces of the bottom plate and the low-voltage metal shielding ring insert to enhance the shielding effect. A fluorocarbon metal paint is sprayed outside the semi-conductive paint to prevent the shielding layer from being damaged by external forces.

[0011] Even further, a grounding terminal is provided at the center of the bottom plate for the convenience of users to ground. The cable outlet is located on one side of the grounding terminal for the convenience of users' secondary wiring. The grounding terminal, pouring port, and cable outlet are distributed in a "pin" shape.

[0012] [[ID=1S]]Even further, a rubber plug is provided between the low-voltage cable and the bottom plate to play a role in sealing and protection.

[0013] Even further, the secondary outgoing line of the low-voltage cable is led out through a shielded cable terminal or an aviation socket, which is convenient for users to install and avoids wrong wiring.

[0014] The advantages of the above technical solutions adopted by the present invention compared with the prior art are as follows:

[0015] 1. High withstand voltage level, maintenance-free, and long service life: Epoxy resin vacuum casting is adopted, and ceramic capacitors are used as components, with a higher withstand voltage level, no need for additional maintenance, a wider temperature adaptation range, especially in environments with large day-night temperature differences in deserts and high summer temperatures, making the life of the mutual inductor longer.

[0016] 2. Small size and convenient wiring: It adopts a split structure, and the high-voltage tapered head interface cable can be installed and fixed in any direction, which reduces the installation space. The low-voltage cable secondary output can be connected to the external cable lead terminal for direct use by the user; it can also be equipped with an aviation socket to facilitate user installation and avoid incorrect wiring.

[0017] 3. Low partial discharge and high measurement accuracy: Except for the primary high-voltage terminal, the remaining outer surfaces are coated with semi-conductive paint and connected to the base plate for grounding, making the internal electric field more uniform, reducing partial discharge and ensuring safe operation; at the same time, it enables the transformer to be used in complex electric field environments, avoids external interference, guarantees error performance, and improves measurement accuracy. Attached Figure Description

[0018] Figure 1 This is a front view of the internal structure of a split-type three-phase AC electronic voltage transformer.

[0019] Figure 2 A bottom view of the external structure of a split-type three-phase AC electronic voltage transformer;

[0020] Figure 3 Top view of the external structure of a split-type three-phase AC electronic voltage transformer;

[0021] Figure 4 A schematic diagram of the installation of a split-type three-phase AC electronic voltage transformer;

[0022] Figure 5 This is the electrical schematic diagram of a split-type three-phase AC electronic voltage transformer.

[0023] In the diagram: 1. Primary high-voltage capacitor; 2. Primary high-voltage terminal; 3. Secondary capacitor; 4. Low-voltage cable; 5. Epoxy resin; 6. Metal shielding mesh; 7. Semi-conductive paint; 8. Grounding terminal; 9. Base plate; 10. Polyurethane resin; 11. Secondary terminal n; 12. Secondary terminal a; 13. Matching cable interface; 14. Cable terminal; 15. Insulator; 16. Injection port; 17. Low-voltage metal shielding ring insert; 18. Low-voltage metal shielding ring; 19. Aviation socket; 20. Rubber plug. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of 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 of this application and are not intended to limit this application; that is, the described embodiments are only a part of the embodiments of this application, and not all of them. The components of the embodiments of this application described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0028] Example 1

[0029] like Figure 1-5 As shown, this embodiment provides a split-type three-phase AC electronic voltage transformer, including three individual insulators. The specific manufacturing process of each individual insulator 15 is as follows: First, the top of the primary high-voltage capacitor 1 is soldered to the bottom of the primary high-voltage terminal 2 via copper wire. The secondary terminal a12 is then soldered to the bottom of the primary high-voltage capacitor 1. After cleaning with alcohol, it is transferred into a mold. During mold assembly, the copper wire soldered between the bottom of the primary high-voltage terminal 2 and the top of the primary high-voltage capacitor 1 should pass through the low-voltage metal shielding ring 18 in the center. The primary high-voltage terminal 2 and the secondary terminal a12 are used to fix the mold, and the insulation distance is adjusted. The primary high-voltage capacitor 1, primary high-voltage terminal 2, secondary terminal a12, secondary terminal n11, and low-voltage metal shielding ring 18 are vacuum cast into insulators using epoxy resin 5. After sandblasting the surface of the insulator 15, a semi-conductive paint 7 and a fluorocarbon paint coating are sprayed to connect the low-voltage metal shielding ring insert 17 to the base plate 9. Two pins of the secondary capacitor 3 are fixed, one to the secondary terminal a12 and the other to the suspended secondary terminal n11. The low-voltage cable 4 passes through the base plate 9, is sealed and protected by the rubber plug 20, and is then led out and fixed. The base plate 9 is provided with a secondary potting port 16. After the single insulator 15 is inverted, the secondary capacitor 3, low-voltage cable 4, secondary terminal a12, and secondary terminal n11 are potted with polyurethane resin 10 through the potting port 16 on the base plate 9. One end of the low-voltage cable 4 is led out to the shielded cable terminal or the cable aviation socket 19, allowing users to freely choose the secondary lead-out method.

[0030] This application converts the primary voltage into a small voltage signal that is proportional to and in phase with the primary voltage by adjusting the capacitance value of the secondary capacitor 3, resulting in extremely low power consumption and significant energy saving. The secondary lead-out line is equipped with a shielded cable terminal to ensure that the small voltage signal is directly delivered to the user end, improving the stability and accuracy of the equipment. The upper part of each insulator 15 is conical, and the lower part is cylindrical, ensuring a tight connection between the current transformer and the matching cable interface 13. Furthermore, the internal components have a uniform insulation distance, resulting in a smaller product size, lighter weight, and more uniform internal and external electric fields, thus improving the insulation level.

[0031] Three separate single insulators 15 are fixed to the matching cable interface 13 through the internal thread of the primary high-voltage terminal 2, realizing the installation and connection of three-phase and high-voltage equipment. They can be installed in different positions along with the cable, or the cable terminal 14 or cable aviation socket 19 can be directly led out according to the user's requirements to avoid wiring errors.

[0032] This application describes a split-type three-phase AC electronic voltage transformer that uses the principle of capacitive voltage division to convert the primary voltage into a small voltage signal that is proportional to and in phase with the primary voltage. This signal is then transmitted to a computer for data processing or to digital instruments and other devices to achieve metering and measurement functions.

[0033] Made with epoxy resin vacuum casting insulation, it features small size, low power consumption, stable insulation, safety and reliability, wide measurement range, no ferromagnetic saturation, advanced functions, and flexible installation and application, further improving the level of automation and digitalization of power system equipment. Three units can be used simultaneously to measure three-phase voltage, or a single unit can be used to measure single-phase voltage.

[0034] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A split-type three-phase AC electronic voltage transformer, characterized in that, It includes three insulators. In each insulator, the primary high-voltage capacitor, the primary high-voltage terminal, the secondary terminal a, the secondary terminal n, and the low-voltage metal shielding ring are vacuum-cast with epoxy resin. One end of the low-voltage cable is connected back to the other end of the low-voltage cable through the secondary terminal n, the secondary capacitor, and the secondary terminal a in the insulator in sequence. The polyurethane resin performs secondary encapsulation on the secondary capacitor, the low-voltage cable, the secondary terminal a, and the secondary terminal n through the pouring port on the insulator bottom plate. The plug part of the primary high-voltage terminal of the three insulators is inserted into an interface of the three-phase cable terminal. Through the voltage division of the primary high-voltage capacitor and the secondary capacitor, the voltage signals required for the three phases are obtained respectively; The plug part of the primary high-voltage terminal is a conical head with internal threads provided therein; The primary high-voltage capacitor is made of a high-voltage-resistant ceramic material. The primary high-voltage capacitor is located below the primary high-voltage terminal and above the secondary terminal n and the secondary terminal a; the secondary capacitor is made of a ceramic material; The low-voltage metal shielding ring is arranged between the primary high-voltage capacitor and the primary high-voltage terminal and is at the transition between the conical head and the cylinder. The connection wire between the primary high-voltage capacitor and the primary high-voltage terminal passes through the center of the low-voltage metal shielding ring.

2. The split-type three-phase AC electronic voltage transformer according to claim 1, characterized in that, The low-voltage metal shielding ring includes a circular metal shielding net and a low-voltage metal shielding ring insert. The two are connected by wire soldering and are sprayed with a semi-conductive paint on the outside.

3. A split-type three-phase AC electronic voltage transformer according to claim 2, characterized in that, A semi-conductive paint is sprayed on the outer surface of the connection between the root of the conical head of the insulator and the bottom plate. This layer of semi-conductive paint contacts the bottom plate and the end face of the low-voltage metal shielding ring insert, and a fluorocarbon metal paint is sprayed outside the semi-conductive paint.

4. A split-type three-phase AC electronic voltage transformer according to claim 1, characterized in that, A grounding terminal is provided at the center position of the bottom plate. The cable outlet is located on one side of the grounding terminal. The grounding terminal, the pouring port, and the cable outlet are distributed in a "pin" shape.

5. A split-type three-phase AC electronic voltage transformer according to claim 1, characterized in that, A rubber plug is arranged between the low-voltage cable and the bottom plate.

6. A split-type three-phase AC electronic voltage transformer according to claim 1, characterized in that, The secondary outgoing line of the low-voltage cable is led out through a shielded cable terminal or an aviation socket.

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