High-voltage coil structure of anti-impact overvoltage epoxy pouring dry-type transformer

Abstract

According to the high-voltage coil structure of the anti-impact overvoltage epoxy pouring dry-type transformer, an electrostatic screen is annularly arranged between a first layer and a second layer at the head end and the tail end of a high-voltage coil wire, the electrostatic screen is made of metal foil, the width of the electrostatic screen is the same as that of the first layer guided by the high-voltage coil, and the width of the electrostatic screen is larger than that of the second layer. According to the high-voltage coil wire turn conductor arrangement structure of the epoxy pouring dry-type transformer, the distribution of ground capacitance of a coil of the transformer is improved, the capacitance is increased, the passing capacity of high-frequency current is improved, and the high-voltage coil wire turn conductor arrangement structure of the epoxy pouring dry-type transformer has the advantages of being simple in structure, convenient to use and high in practicability. When the transformer encounters impact overvoltage, the overvoltage gradient of the first layer at the head end and the first layer at the tail end can be reduced, protection layer insulation and turn insulation of the wire are not damaged, the impact overvoltage resistance of the epoxy pouring dry-type transformer is improved, and reliable operation of the transformer is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-voltage coils of dry-type transformers resistant to impulse overvoltage, and specifically relates to a high-voltage coil structure of epoxy-cast dry-type transformers resistant to impulse overvoltage. Background Art

[0002] With the continuous improvement of urban power supply requirements and the advancement of transformer technology, the use of dry-type transformers has become very common in my country. Dry-type transformers are widely used in all walks of life because of their advantages such as energy saving, safety, reliability, and good flame retardancy.

[0003] When the working voltage of the dry-type transformer reaches 35kV and above, the line often suffers from lightning strikes or operating overvoltage. When the high-voltage coil of the transformer is subjected to lightning or operating overvoltage, due to the steep waveform of the shock wave and the high equivalent frequency, the shock current at this time begins to flow mainly through the capacitive path between the high-voltage coil of the transformer and the ground, rather than through the inductive path of the coil. Due to the multi-stage layered structure of the high-voltage coil of the epoxy-cast dry-type transformer, the capacitance distribution of the coil to each point on the ground is different, such as Figure 3 and Figure 4 As shown, the impact current passing through the winding is very unevenly distributed from beginning to end, resulting in a large difference in voltage gradient, which will have a great impact on the interlayer insulation at the beginning and end of the transformer coil and the interturn insulation of the first few turns of the wire, and even directly cause the insulation breakdown between the coil layers or turns, causing the transformer coil to fail and the transformer to stop operating.

[0004] There is no better product design solution in the industry to solve the problem of impulse overvoltage of epoxy cast dry-type transformers above 35kV, which limits the development and application of epoxy cast dry-type transformers to higher voltages. Utility Model Content

[0005] In order to solve the above problems, this paper proposes an epoxy cast dry-type transformer high-voltage coil structure that is resistant to impact overvoltage. The high-voltage coil of the dry-type transformer is internally wound with a high-voltage coil conductor, and interlayer insulation is provided between each layer of the high-voltage coil conductor. An electrostatic screen is provided in an annular manner between the first layer and the second layer at both ends of the high-voltage coil conductor. The material of the electrostatic screen is metal foil, and the width of the electrostatic screen is the same as the width of the first layer of the high-voltage coil guide. The head and tail annular butt-jointed sides of the electrostatic screen are overlapped and connected to each other, and the outer sides of the overlapping edges on both sides of the electrostatic screen are provided with electrostatic screen head and tail overlap insulation, and insulating material is provided between the surface of the electrostatic screen and the high-voltage coil conductor on both sides. The surface of the electrostatic screen is welded with a metal connecting wire, the metal connecting wire is welded and connected to the first turn wires of the inner and outer layers of the high-voltage coil conductor, and the outer side of the welding point of the metal connecting wire is outwrapped with an insulating material. By designing an epoxy cast dry-type transformer high-voltage coil turn conductor arrangement structure, the distribution of the transformer coil-to-ground capacitance is improved, the capacitance is increased, and the passing capacity of high-frequency current is increased. When the transformer encounters an impact overvoltage, the overvoltage gradient of the first layer at the front and end can be reduced, the protective layer insulation and the turn insulation of the conductor are not damaged, the impact overvoltage resistance of the epoxy cast dry-type transformer is improved, and the reliable operation of the transformer is guaranteed.

[0006] The outside of the high-voltage coil conductor is provided with coil end insulation, coil outer layer insulation and coil inner layer insulation, the outside of both ends of the high-voltage coil conductor is provided with coil end insulation, the outside of the high-voltage coil conductor is provided with coil outer layer insulation, the inside of the high-voltage coil conductor is provided with coil inner layer insulation, the end and the inside of the high-voltage coil are provided with iron core grounding components, the inside of the high-voltage coil is provided with a low-voltage coil, and insulating material is cast between the high-voltage coil conductor and the interlayer insulation, and the insulating material is epoxy resin. The insulating material is epoxy resin, and the application can improve the voltage level of the epoxy cast dry transformer, and provides a solution for the design and manufacture of epoxy cast dry transformer high-voltage coils with higher voltage levels.

[0007] Beneficial effects:

[0008] By designing a high-voltage coil turn conductor arrangement structure of an epoxy-cast dry-type transformer, the distribution of the transformer coil-to-ground capacitance is improved, the capacitance is increased, and the passing capacity of high-frequency current is increased. When the transformer encounters an impact overvoltage, the overvoltage gradient of the first layer at the beginning and the end can be reduced, and the insulation of the protective layer and the turn insulation of the conductor are not damaged, thereby improving the ability of the epoxy-cast dry-type transformer to resist impact overvoltage and ensuring the reliable operation of the transformer.

[0009] After adopting this new epoxy cast dry-type transformer high-voltage coil structure, the metal electrostatic screen inside the high-voltage coil can increase the distribution of the coil's capacitance to the ground, thereby reducing the overvoltage gradient of the first layer of the coil, reducing the impact of the impulse overvoltage on the first and end interlayer insulation of the coil and the insulation between the turns of the wire, weakening the damage of the impulse voltage to the insulation performance of the coil, and improving the safety and reliability of the transformer coil. The application of this structure can increase the voltage level of the epoxy cast dry-type transformer, and provide a solution for the design and manufacture of epoxy cast dry-type transformer high-voltage coils with higher voltage levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the inner side of the high-voltage coil structure of an epoxy-cast dry-type transformer that is resistant to impulse overvoltage;

[0011] Figure 2 It is a top view of the high voltage coil structure of epoxy cast dry-type transformer that is resistant to impulse overvoltage;

[0012] Figure 3 It is a schematic diagram of the inner side of the existing dry-type transformer high-voltage coil structure;

[0013] Figure 4 It is a top view of the existing dry-type transformer high-voltage coil structure;

[0014] In the figure; 1. high-voltage coil conductor, 2. interlayer insulation, 3. coil end insulation, 4. coil outer layer insulation, 5. coil inner layer insulation, 6. core grounding component, 7. high-voltage coil incoming terminal, 8. low-voltage coil, 9. electrostatic screen, 10. metal connecting wire, 11. electrostatic screen end-to-end overlap insulation. DETAILED DESCRIPTION

[0015] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0016] High-voltage coil conductor 1, interlayer insulation 2, coil end insulation 3, coil outer layer insulation 4, coil inner layer insulation 5, core grounding component 6, high-voltage coil incoming terminal 7, low-voltage coil 8, electrostatic screen 9, metal connecting wire 10, electrostatic screen end-to-end overlap insulation 11.

[0017] like Figure 1 , 2 As shown;

[0018] A high-voltage coil structure of an epoxy-cast dry-type transformer that resists impact overvoltage, wherein a high-voltage coil conductor 1 is wound inside the high-voltage coil of the dry-type transformer, and an interlayer insulation 2 is provided between each layer of the high-voltage coil conductor 1. An electrostatic screen 9 is provided in an annular manner between the first layer and the second layer at both ends of the high-voltage coil conductor 1. The electrostatic screen 9 is made of metal foil, and the width of the electrostatic screen 9 is the same as the width of the first layer of the high-voltage coil guide. The annular butt-jointed side edges of the electrostatic screen 9 are overlapped and connected to each other, and the outer sides of the overlapped edges on both sides of the electrostatic screen 9 are provided with electrostatic screen overlap insulation 11 at the head and tail, and insulating materials are provided between the surface of the electrostatic screen 9 and the high-voltage coil conductor 1 on both sides, and a metal connecting wire 10 is provided on the surface of the electrostatic screen 9 in a welded manner. The metal connecting wire 10 is welded to the first turn wires of the inner and outer layers of the high-voltage coil conductor 1, and the outer side of the welding point of the metal connecting wire 10 is provided with insulating material in an outwardly wrapped manner. The outer side of the high-voltage coil conductor 1 is provided with a coil end insulation 3, a coil outer layer insulation 4 and a coil inner layer insulation 5. The outer sides of both ends of the high-voltage coil conductor 1 are provided with a coil end insulation 3, the outer side of the high-voltage coil conductor 1 is provided with a coil outer layer insulation 4, the inner side of the high-voltage coil conductor 1 is provided with a coil inner layer insulation 5, the end and the inner side of the high-voltage coil are provided with a core grounding component 6, the inner side of the high-voltage coil is provided with a low-voltage coil 8, and the high-voltage coil conductor 1 and the interlayer insulation 2 are provided with insulating material in a cast manner, and the insulating material is epoxy resin.

[0019] Implementation examples;

[0020] When the high-voltage coil is produced and wound, a metal foil electrostatic screen 9 is placed between the first and second layers inside the head and tail ends. The electrostatic screen 9 is as wide as the line segment of the first layer. The electrostatic screen 9 is wound into a ring and separated by insulating material at the overlap of the electrostatic flat head and tail to prevent the electrostatic screen 9 from becoming a closed conductive ring; the electrostatic screen 9 is separated from the high-voltage wires on both sides by insulating materials, and a metal wire is welded on the electrostatic screen 9. The metal wire is welded to the first turn wires of the inner and outer layers respectively, and the welding position is wrapped with insulating material. Finally, the coil is cast according to the process to make it a whole. The upper and lower parts and the inside and outside of the high-voltage coil wire 1 have a certain thickness of insulating layers formed by epoxy resin.

[0021] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An epoxy cast dry-type transformer high-voltage coil structure resistant to impulse overvoltage, wherein a high-voltage coil conductor is wound inside the dry-type transformer high-voltage coil, and interlayer insulation is provided between each layer of high-voltage coil conductors, characterized in that: An electrostatic screen is provided in a ring shape between the first layer and the second layer at both ends of the high-voltage coil conductor. The material of the electrostatic screen is metal foil. The width of the electrostatic screen is the same as the width of the first layer of the high-voltage coil guide. The front and rear annular butt joint sides of the electrostatic screen are overlapped and connected to each other. The outer sides of the overlapping edges on both sides of the electrostatic screen are provided with electrostatic screen overlap insulation. Insulating material is provided between the two sides of the surface of the electrostatic screen and the high-voltage coil conductor. A metal connecting wire is welded on the surface of the electrostatic screen. The metal connecting wire is welded to the first turn wires of the inner and outer layers of the high-voltage coil conductor, and the outer sides of the welding points of the metal connecting wires are provided with insulating material.

2. The epoxy cast dry-type transformer high voltage coil structure with impact overvoltage resistance according to claim 1 is characterized in that: The outside of the high-voltage coil conductor is provided with coil end insulation, coil outer layer insulation and coil inner layer insulation, the outside of both ends of the high-voltage coil conductor is provided with coil end insulation, the outside of the high-voltage coil conductor is provided with coil outer layer insulation, and the inside of the high-voltage coil conductor is provided with coil inner layer insulation.

3. The epoxy cast dry-type transformer high voltage coil structure with impact overvoltage resistance according to claim 1 is characterized in that: The end and the inner side of the high-voltage coil are both provided with an iron core grounding component, and the inner side of the high-voltage coil is provided with a low-voltage coil.

4. The epoxy cast dry-type transformer high voltage coil structure with impact overvoltage resistance according to claim 1 is characterized in that: Insulating material is cast between the high-voltage coil conductor and the interlayer insulation, and the insulating material is epoxy resin.

5. The epoxy cast dry-type transformer high voltage coil structure with impact overvoltage resistance according to claim 1 is characterized in that: The insulating material is epoxy resin.

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