Device for improving electric field distribution of oil-immersed electromagnetic voltage transformer
By using a combination of shielding cylinder and connecting leads in the oil-immersed electromagnetic voltage transformer, the electric field distribution is improved, the problem of uneven electric field caused by line instability is solved, the stability and safety of the transformer are improved, the service life is extended, and the operating cost of the power grid is reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2026-03-27
AI Technical Summary
Oil-immersed electromagnetic voltage transformers are easily impacted in 35kV non-effectively grounded systems due to line instability, resulting in uneven internal electric field distribution, insulation damage, reduced service life, and increased power grid operating costs.
The transformer employs a combination structure of a shielding cylinder and connecting leads. The shielding cylinder is made of a material with good insulation properties and is connected to the external ground wire of the porcelain bushing via connecting leads, thereby reducing the potential gradient on the surface of the transformer and improving the internal electric field distribution.
It effectively reduces the possibility of partial discharge in instrument transformers, improves operational stability and service life, reduces replacement frequency, reduces power grid operating costs, and improves power grid security.
Smart Images
Figure CN224053004U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the technical field of voltage transformer, especially relates to a device for improving oil immersed electromagnetic voltage transformer electric field distribution. BACKGROUND
[0002] The electromagnetic voltage transformer is a device for proportionally transforming voltage or current by electromagnetic induction principle, and its main purpose is to supply power to measuring instruments and relay protection devices, to measure voltage, power and electric energy of a line, or to protect valuable equipment, motors and transformers in the line when the line has a fault. However, in the existing power system, especially in the 35kV non-effective grounding system, the insulation of the oil immersed electromagnetic voltage transformer is easily impacted due to the instability of the line, which causes uneven internal electric field distribution of the transformer and further causes insulation damage. This not only reduces the service life of the transformer itself, increases the replacement frequency and increases the operation cost of the power grid, but also threatens the overall safety of the power grid and further causes greater economic losses. SUMMARY
[0003] The utility model aims at providing a device for improving the electric field distribution of an oil immersed electromagnetic voltage transformer, to solve the technical problem that the oil immersed electromagnetic voltage transformer is easily impacted due to the instability of the line when used in the existing power system, which causes uneven internal electric field distribution and insulation damage.
[0004] To achieve the above-mentioned purpose, the specific technical scheme of the utility model is as follows:
[0005] A device for improving the electric field distribution of an oil immersed electromagnetic voltage transformer, comprising a shielding cylinder and a connecting lead, wherein the upper end of the shielding cylinder corresponds to the porcelain sleeve of the transformer, a pair of corresponding connecting leads are respectively arranged on the left and right sides of the lower part of the outer sidewall of the shielding cylinder, the inner side end of the connecting lead is connected to the sidewall of the shielding cylinder through a corresponding connecting piece, and the shielding cylinder is connected to the ground wire outside the porcelain sleeve through the connecting lead.
[0006] Further, the shielding cylinder comprises a hollow cylindrical framework cylinder with two open ends, a corresponding inner lining layer is arranged on the sidewall of the inner cavity of the framework cylinder, the inner lining layer is attached to and fixed on the inner side of the sidewall of the framework cylinder, the two ends of the inner lining layer respectively extend outward along the profile of the sidewall of the two ends of the framework cylinder and form a wrapping around the two ends of the framework cylinder, thereby forming a pair of corresponding outer adhesive rings at the two ends of the sidewall of the framework cylinder, the two outer adhesive rings are respectively adhered to the outer surface of the corresponding end of the sidewall of the framework cylinder, the corresponding two connecting pieces are respectively attached to the corresponding two sides of the outer adhesive ring at the lower end of the framework cylinder, the outer side of the connecting piece is provided with a binding ring, and the binding ring binds and fixes the two connecting pieces to the outer side of the outer adhesive ring.
[0007] Furthermore, the skeleton tube is made of a material with good insulation properties, and the inner lining is a semi-conductive paper tube formed by bonding and adhering semi-conductive paper to the inner wall of the skeleton tube. The seams are overlapped, and the overlap depth of the paper edges is not less than 10mm. The outer ring is formed by extending the end of the semi-conductive paper tube outward and folding it in the opposite direction. The binding ring is made of semi-conductive crepe paper tape.
[0008] Furthermore, the outer end of the connecting lead is provided with a corresponding terminal lug, and the connecting lead is connected to the ground wire through the terminal lug.
[0009] Furthermore, the wiring lug is connected to the inner side of the upper top plate on the top of the transformer oil tank, and the pressure ring outside the porcelain bushing is connected to the outer side of the upper top plate on the top of the transformer oil tank by corresponding bolts.
[0010] Furthermore, the height of the shielding cylinder is 10%-15% of the dry arc distance of the porcelain sleeve, its outer diameter corresponds to the inner diameter of the porcelain sleeve, and its bottom end extends downwards from the porcelain sleeve.
[0011] This invention relates to a device for improving the electric field distribution of an oil-immersed electromagnetic voltage transformer. Through the cooperation of the shielding cylinder and the connecting leads, the device effectively reduces the potential gradient on the transformer surface, improves the internal electric field distribution of the transformer, reduces the possibility of partial discharge, reduces the impact of unstable voltage on the transformer insulator, improves the overall operational stability and service life of the transformer, reduces the frequency of transformer replacement, reduces the operating cost of the power grid, improves the overall safety of the power grid, and improves the overall economic benefits of power grid operation. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of a half-section of the present invention;
[0013] Figure 2 This utility model Figure 1 A top-view structural diagram;
[0014] Figure 3 This is a schematic diagram of the connecting lead structure of this utility model;
[0015] Figure 4 This is a schematic diagram of the structure of this utility model during installation and use;
[0016] Figure 5 This utility model Figure 1 A magnified view of a section at point A in the middle;
[0017] The markings in the diagram are as follows: 1. Shielding cylinder; 11. Skeleton cylinder; 12. Inner lining layer; 13. Outer ring; 14. Binding ring; 2. Connecting lead wire; 21. Connecting piece; 22. Wiring lug; 3. Porcelain sleeve; 31. Pressure ring; 32. Oil tank; 33. High voltage lead wire. Detailed Implementation
[0018] To better understand the purpose, structure, and function of this utility model, the following detailed description of a device for improving the electric field distribution of an oil-immersed electromagnetic voltage transformer is provided in conjunction with the accompanying drawings.
[0019] like Figures 1-5 As shown, the device for improving the electric field distribution of an oil-immersed electromagnetic voltage transformer includes a shielding cylinder 1. Connecting leads 2 are provided on the outer wall of the lower part of the shielding cylinder 1. A pair of corresponding connecting leads 2 are respectively located on the left and right sides of the shielding cylinder 1. This improves the balance of the shielding cylinder 1 when it is installed and connected externally. Corresponding connecting pieces 21 are provided on the inner ends of the connecting leads 2, which are fixedly connected to the corresponding side walls of the shielding cylinder 1. In use, the shielding cylinder 1 is fitted onto the outer ring of the high-voltage lead 33, and its upper end is inserted into the porcelain sleeve 3 on the transformer, corresponding to the oil tank 32. In the lower inner cavity, the shielding cylinder 1 is located between the porcelain sleeve 3 and the high-voltage lead 33. The shielding cylinder 1 is connected to the ground wire outside the porcelain sleeve 3 through the connecting lead 2. In this embodiment, the outer end of the connecting lead 2 is connected to the top plate of the oil tank 32 below the outer ring pressure ring 31 of the porcelain sleeve 3, so that it is grounded together with the oil tank 32. During operation, the connecting lead 2 makes the shielding cylinder 1, the pressure ring 31 and the oil tank 32 have the same potential, reducing the possibility of tip discharge of the internal high-voltage lead 33 and the external pressure ring 31 due to the influence of the electric field, thereby reducing the impact of unstable lines on the insulator of the transformer.
[0020] The shielding cylinder 1 includes a skeleton cylinder 11, which is a hollow cylinder with openings at both the top and bottom. A corresponding inner lining layer 12 is provided on the inner wall of the inner cavity of the skeleton cylinder 11. The inner lining layer 12 is attached to the inner side surface of the side wall of the skeleton cylinder 11 and the two are fixedly bonded together with corresponding adhesive. The top and bottom ends of the inner lining layer 12 extend outward along the contours of the side walls at both ends of the skeleton cylinder 11, forming a wrap around both ends of the skeleton cylinder 11, thereby forming a pair of corresponding outer outer rings 13 at both ends of the skeleton cylinder 11. All 13 are annular, and their inner diameter is the same as the outer diameter of the corresponding end side wall of the skeleton cylinder 11. Their inner rings are attached to the corresponding end outer surface of the side wall of the skeleton cylinder 11, and the two are bonded to each other with corresponding glue. A pair of corresponding connecting pieces 21 are respectively provided on both sides of the outer ring 13 on the lower side of the skeleton cylinder 11. The inner side of the connecting piece 21 is attached to the outer side of the corresponding side of the outer ring 13. The outer side of the connecting piece 21 is provided with a corresponding binding ring 14, which binds the two connecting pieces 21 to the outer side of the outer ring 13.
[0021] Further, the skeleton cylinder 11 is made of a material with good insulation performance, such as glass silk cloth or paper, etc., the inner lining layer 12 is a semi-conductive paper cylinder formed by pasting semi-conductive paper flat on the inner side wall of the skeleton cylinder 11, the joint of the semi-conductive paper adopts the lap joint mode, the depth dimension of the overlapping of the adjacent paper edges of the lap joint part is not less than 10 mm, which prevents the inner lining layer 12 from having gaps, thereby reducing the function of the shielding cylinder 1, the outer ring 13 is formed by outwardly and reversely folding the extension of the end of the semi-conductive paper cylinder, the binding ring 14 is made of semi-conductive corrugated paper tape, which binds the connecting piece 21 to the outside of the outer ring 13 of the shielding cylinder 1 through multiple turns of winding, so that the insulation of the transformer is better protected from being damaged by unstable voltage of unstable line, and at the same time, the impulse current in the porcelain sleeve 3 can be guided to the ground wire outside the transformer through the connecting lead 2, so as to avoid more dangers of the power grid, in the embodiment, the skeleton cylinder 11 is made of glass silk cloth, which is uniform and continuous along the equidiameter spiral line, and has good insulation, high heat resistance, small moisture absorption, softness and high tensile strength, so that the shielding cylinder 1 is more difficult to be damaged in the unstable power grid line, and is more suitable for the uneven electric field environment of the transformer, thereby improving the overall service life of the transformer.
[0022] Further, the outer side end of the connecting lead 2 is provided with a corresponding annular terminal lug 22, which is fixedly connected therebetween, and the connecting lead 2 is connected to the ground wire through the terminal lug 22, so that the use of the terminal lug 22 makes the connecting lead 2 more convenient and fast when connected to the outside, and makes the external connection more firm and not easy to fall off, and the conduction is better.
[0023] Further, the connecting piece 21, the connecting lead 2 and the terminal lug 22 are all made of a material with good conductivity, in the embodiment, the connecting piece 21 is made of copper foil, the connecting lead 2 is made of copper wire, and the terminal lug 22 is also made of copper, which has good conductivity and is not easy to be damaged, thereby improving the service life.
[0024] Further, the terminal lug 22 is detachably fixedly connected to the inner side of the upper top plate on the top of the transformer oil tank 32, and the pressing ring 31 outside the porcelain sleeve 3 is connected to the outer side of the upper top plate on the top of the transformer oil tank 32 through corresponding bolts, thereby realizing the connection between the pressing ring 31 and the inner lining layer 12 in the inner cavity of the shielding cylinder 1, so that the setting can prevent the pressing ring 31 from putting points on the high-voltage lead 33 in the porcelain sleeve 3 when the electric field is uneven, thereby causing greater danger of the power grid.
[0025] Further, the height of the shielding cylinder 1 is 10%-15% of the dry arc distance of the porcelain sleeve 3, in the embodiment, the height is not higher than 160 mm, the outer diameter corresponds to the inner diameter of the corresponding porcelain sleeve 3, the outer surface of the side wall of the inserted part in the inner cavity of the porcelain sleeve 3 is attached to the inner cavity side wall of the porcelain sleeve 3, the lower end extends downward from the porcelain sleeve 3, and the bottom end is located at a position 5 mm lower than the inner side of the upper top plate of the oil tank, so that the insulation protection performance is better.
[0026] In use, the shielding cylinder 1 is fitted onto the high-voltage lead 33 at the bottom of the porcelain sleeve 3 on the high-voltage side of the transformer. Its upper end is inserted into the inner cavity of the porcelain sleeve 3 from the lower port. At this time, the upper part of the shielding cylinder 1 is between the lower end of the porcelain sleeve 3 and the corresponding high-voltage lead 33 inside it. The outer surface of its side wall is attached to the inner surface of the inner cavity of the porcelain sleeve 3. The two connecting leads 2 on the lower side of the shielding cylinder 1 extend from the bottom of the porcelain sleeve 3 to the left and right sides respectively. In this embodiment, the wiring lugs 22 at the ends of the two connecting leads 2 are detachably and fixedly connected to the inner side of the upper top plate on the left and right sides of the top of the transformer oil tank 32 by corresponding external bolts. The connecting leads 2 are connected to the external grounding wire through the oil tank 32. The pressure ring 31 on the outside of the porcelain sleeve 3 is connected to the outer side of the upper top plate of the transformer oil tank 32 by corresponding external bolts. The pressure ring 31 is connected to the connecting leads 2 through the upper top plate. At this time, the lower end of the shielding cylinder 1 extends towards the oil tank 32 below the porcelain sleeve 3. When the power grid line is running, the shielding cylinder 1, placed in an electric field, will experience electrostatic induction. Under the influence of the connecting lead 2, the shielding cylinder 1 is in electrostatic equilibrium, and the electric field strength inside is zero everywhere. This avoids the generation of strong electric fields, thereby eliminating the electric field conditions that would lead to tip discharge, and thus preventing tip discharge of the internal high-voltage lead 33. In addition, the shielding cylinder 1 also acts as a shield against external electric fields. When the electric field of the pressure ring 31 is uneven, it can neutralize and conduct its unstable current, thereby reducing the potential gradient on the surface of the transformer and preventing the external electric field from affecting the interior of the shielding cylinder. Thus, even if a strong external electric field exists, the high-voltage lead 33 inside the shielding cylinder 1 will not be affected by the electric field, further avoiding tip discharge caused by a strong external electric field forming at the tip of the pressure ring 31, thereby reducing the phenomenon of electric field concentration and lowering the possibility of partial discharge. In summary, the shielding cylinder 1 and the connecting lead 2 work together to reduce the impact and damage of the uneven electric field caused by line instability on the transformer insulation.
[0027] This invention relates to a device for improving the electric field distribution of an oil-immersed electromagnetic voltage transformer. By adding shielding to the high-voltage end of the transformer, the potential gradient on the transformer surface can be effectively reduced, confining the high-voltage electric field within the shielding layer, thus enhancing its safety. It also improves the distribution of the electric field inside the transformer, making it more uniform. This not only reduces the phenomenon of electric field concentration but also lowers the possibility of partial discharge. This effectively reduces the impact of unstable voltage on the transformer insulation, improves the reliability and stability of transformer operation, extends the overall service life of the equipment, and enhances the stability of the safe operation of the power system.
[0028] It can be understood that the utility model is described through some embodiments, and the person skilled in the art knows that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the utility model. In addition, under the guidance of the utility model, these features and embodiments can be modified to adapt to specific conditions and materials without departing from the spirit and scope of the utility model. Therefore, the utility model is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the application belong to the scope protected by the utility model.
Claims
1. An apparatus for improving electric field distribution of an oil-immersed electromagnetic voltage transformer, characterized by comprising: It includes shielding cylinder (1) and connecting lead (2), wherein the upper end of shielding cylinder (1) corresponds to the porcelain sleeve (3) of the transformer, a pair of corresponding connecting leads (2) are respectively arranged on the left and right sides of the lower part of the outer side wall of shielding cylinder (1), the inner side end of connecting lead (2) is connected to the side wall of shielding cylinder (1) through the corresponding connecting sheet (21), and shielding cylinder (1) is connected to the ground wire outside porcelain sleeve (3) through connecting lead (2).
2. The device for improving electric field distribution of oil-immersed electromagnetic voltage transformers according to claim 1, characterized in that, The shielding cylinder (1) includes an inner hollow two-end opening cylindrical framework cylinder (11), and a corresponding inner lining layer (12) is arranged on the inner cavity side wall of the framework cylinder (11). The inner lining layer (12) is attached and fixed to the inner side of the side wall of the framework cylinder (11). The two ends of the inner lining layer (12) respectively extend outward along the side wall profile of the two ends of the framework cylinder (11) and form a wrapping at the two ends of the framework cylinder (11), thereby forming a corresponding pair of outer attached rings (13) at the two ends of the side wall of the framework cylinder (11). The two outer attached rings (13) are respectively attached and fixed to the outer surfaces of the corresponding ends of the side wall of the framework cylinder (11). The outer side of the connecting sheet (21) is provided with a binding ring (14), and the binding ring (14) binds and fixes the two connecting sheets (21) to the outer side of the outer attached ring (13).
3. The device for improving electric field distribution of an oil-immersed electromagnetic voltage transformer according to claim 2, characterized in that, The framework cylinder (11) is made of a material with good insulating properties. The inner lining layer (12) is a semiconductive paper cylinder formed by attaching and fixing semiconductive paper to the inner side wall of the framework cylinder (11). The joint is in a lap joint manner. The outer attached ring (13) is formed by outwardly reversing and folding the end portion of the semiconductive paper cylinder. The binding ring (14) is made of semiconductive corrugated paper.
4. The device for improving electric field distribution of oil-immersed electromagnetic voltage transformers according to claim 1, characterized in that, The outer side end of the connecting lead (2) is provided with a corresponding terminal lug (22), and the connecting lead (2) is connected to the ground wire through the terminal lug (22).
5. The device for improving electric field distribution of an oil-immersed electromagnetic voltage transformer according to claim 4, characterized in that, The connecting sheet (21), the connecting lead (2) and the terminal lug (22) are all made of a material with good conductivity.
6. The device for improving electric field distribution of oil-immersed electromagnetic voltage transformers according to claim 4, characterized in that, The terminal lug (22) is connected to the inner side of the upper top plate on the top of the transformer oil tank (32). The pressing ring (31) outside the porcelain sleeve (3) is connected to the outer side of the upper top plate on the top of the transformer oil tank (32) through corresponding bolts.
7. The device for improving electric field distribution of oil-immersed electromagnetic voltage transformers according to claim 1, characterized in that, The height of the shielding cylinder (1) is 10%-15% of the dry arc distance of the porcelain sleeve (3). The outer diameter of the shielding cylinder (1) corresponds to the inner diameter of the porcelain sleeve (3), and the bottom end of the shielding cylinder (1) extends downward to the porcelain sleeve (3).