High-voltage alternating-current and direct-current wall bushing

Abstract

The invention relates to a wire or cable and a protection device which penetrate through a wall, a floor or a ceiling and are installed in a building, for example, and particularly relates to a high-voltage alternating-current and direct-current wall bushing. The high-voltage alternating-current and direct-current wall bushing comprises a bushing body and a central conducting rod in the bushing body, an end cover is arranged at the indoor end of the bushing body, a cylindrical sealing section is arranged on the side, facing the bushing body, of the end cover in the axial direction of the bushing body, and a magnetic liquid sealing device is arranged in the sealing section and comprises a permanent magnet; the permanent magnet and the center conducting rod keep an interval used for forming a rotating magnetic field loop, pole shoe rings are arranged on the two sides of the permanent magnet, magnetic liquid is arranged between the pole shoe rings and the center conducting rod, and a cover plate used for clamping and fixing the magnetic liquid sealing device is arranged at the end, away from the end cover, of the sealing section. No mechanical wear exists between the central conducting rod and the magnetic liquid sealing device, so that the generation of metal particles in the wall bushing can be reduced, and the air tightness of the wall bushing can be enhanced.

Description

Technical Field

[0001] The invention relates to an electric wire or cable and a protective device which penetrates a wall, a floor or a ceiling and is installed in a building, and in particular to a high-voltage AC / DC wall bushing. Background Art

[0002] In AC and DC power transmission and transformation projects, the wall bushing is the only electrical component connecting the inside and outside of the valve hall, carrying the voltage and current of the entire line. Its performance reliability determines the safety and stability of the entire line. The current-carrying conductor of the wall bushing is the central conductive rod. Under high-voltage and ultra-high-voltage working conditions, the central conductive rod will expand and elongate in the axial direction due to the heat generated by the large current flow. In order to prevent the electric field distortion caused by the sagging caused by the expansion and elongation of the central conductive rod, a corrugated tube is generally used to connect the end of the wall bushing on the indoor side.

[0003] Article numbered 2095-509X (2019) 08-0111-04, “Random Vibration Analysis of DC Wall Bushing in High Voltage Transmission Lines under Transportation Conditions” discloses a wall bushing structure, wherein the structure of the indoor end includes an end cover at the indoor end of an insulating shell, the end cover has a central opening and a plug-in mating section extending inward along the opening for plugging and mating with a central conductive rod, and spring contacts are provided on the inner wall of the plug-in mating section, which can conduct current and provide corresponding clamping force to achieve a stable conductive connection between the central conductive rod and the end cover. When current is flowing, the current enters the end cover of the insulating shell through the central conductive rod, and then flows through the indoor end cover to enter the conductive joint and enter the indoor power network. Since there is no fixed connection between the central conductive rod and the plug-in mating section, friction or vibration occurs between the central conductive rod and the spring contact finger during transportation or operation, which easily generates metal particles. After the metal particles enter the gas insulation cavity, flashover is likely to occur, causing the insulation structure to be punctured, thus affecting the insulation performance of the wall bushing.

[0004] Existing wall bushings generally adopt a bellows structure. When the central conductive rod is heated and elongated, the bellows is driven to elongate, balancing the axial deformation of the central conductive rod, reducing the deflection change of the central conductive rod, and avoiding serious sagging problems that lead to electric field distortion. However, metal particles are easily generated due to the relative sliding between the spring contact fingers and the central conductive rod. After the metal particles enter the gas insulation cavity, flashover is likely to occur, causing the insulation structure to be punctured, affecting the insulation performance of the wall bushing. Summary of the invention

[0005] The object of the present invention is to provide a high voltage AC / DC wall bushing to solve the problem that metal particles are easily generated at the existing indoor end and the insulation performance is poor due to poor sealing performance.

[0006] The technical solution of the high voltage AC / DC wall bushing of the present invention is: A high-voltage AC / DC wall bushing comprises a tube body and a central conductive rod inside the tube body, an end cap is arranged at the indoor end of the tube body, a cylindrical sealing section is arranged along the axial direction of the tube body on the side of the end cap facing the tube body, a magnetic liquid sealing device is arranged inside the sealing section, the magnetic liquid sealing device comprises an annular permanent magnet, the permanent magnet and the central conductive rod are kept at a distance for forming a rotating magnetic field loop, pole shoe rings are arranged on both sides of the permanent magnet, the outer wall of the pole shoe ring is tightly installed with the inner wall of the sealing section, the inner diameter of the pole shoe ring is larger than the outer diameter of the central conductive rod, magnetic liquid is arranged between the pole shoe ring and the central conductive rod, and a cover plate for clamping and fixing the magnetic liquid sealing device is arranged at one end of the sealing section away from the end cap.

[0007] Furthermore, a sealing ring is provided between the pole shoe ring and the sealing section.

[0008] Furthermore, an annular groove is provided on the inner wall of the pole shoe ring.

[0009] Furthermore, a bellows is fixedly installed on the end cover facing away from the magnetic liquid sealing device, and a sealing plate that can move axially along the tube body is fixedly installed on the side of the bellows away from the end cover, and the central conductive rod is inserted into the sealing plate and fixedly connected to the sealing plate.

[0010] Furthermore, a cylindrical guide section is arranged on one side of the sealing plate facing the end cover along the axial direction of the tube body, and a sealing ring cooperating with the central conductive rod is installed on the guide section.

[0011] Furthermore, a sleeve for radial support is provided on a side of the pole shoe ring away from the permanent magnet.

[0012] Furthermore, a spacer is provided between the sleeve and the corresponding pole shoe ring.

[0013] Beneficial effects: The present invention is an improved invention. The high-voltage AC / DC wall bushing of the present invention comprises a tube body and a central conductive rod inside the tube body. An end cap is provided at the indoor end of the tube body. A cylindrical sealing section is provided along the axial direction of the tube body on the side of the end cap facing the tube body. A magnetic liquid sealing device is provided inside the sealing section. The magnetic liquid seal has the advantages of sealing reliability, no leakage, no mechanical wear, long service life, high working efficiency, etc. It is suitable for static sealing and dynamic sealing. The magnetic liquid sealing device comprises an annular permanent magnet. The permanent magnet and the central conductive rod maintain a gap for forming a rotating magnetic field loop. The permanent magnet and the central conductive rod do not contact each other. Pole shoe rings are provided on both sides of the permanent magnet. The permanent magnet, the pole shoe ring and the central conductive rod form a rotating magnetic field loop. The inner diameter of the pole shoe ring is larger than the outer diameter of the center conductive rod, so that a gap for filling magnetic liquid is left between the two. Magnetic liquid is arranged between the pole shoe ring and the center conductive rod. Under the action of the rotating magnetic field loop, the magnetic liquid is firmly adsorbed between the pole shoe ring and the center conductive rod to form an "O"-shaped ring, which completely blocks the gap to achieve a sealing effect. A cover plate for clamping and fixing the magnetic liquid sealing device is arranged at the end of the sealing section away from the end cover. There is no mechanical wear between the center conductive rod and the magnetic liquid sealing device, which can reduce the generation of metal particles inside the wall bushing. At the same time, the dynamic sealing effect of the magnetic liquid sealing device is better than that of sealing with a sealing ring, which is beneficial to enhancing the air tightness of the wall bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A schematic structural diagram of an embodiment of a high-voltage AC / DC wall bushing of the present invention; Figure 2 for Figure 1 A partial enlarged view of the magnetic liquid sealing device.

[0015] In the figure: 1. tube body; 2. central conductive rod; 3. end cover; 4. sealing section; 5. permanent magnet; 6. pole shoe ring; 7. cover plate; 8. sleeve; 9. spacer; 10. bellows; 11. sealing plate; 12. guide section; 13. spring contact finger; 14. sealing ring; 15. magnetic liquid; 16. equalizing ring; 17. shielding cover. DETAILED DESCRIPTION

[0016] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0017] During the operation of high-voltage AC / DC wall bushings, the indoor end needs to meet the requirements of static sealing and dynamic sealing at the same time. The sealing performance of the indoor end will affect the insulation performance of the high-voltage AC / DC wall bushings. The concept of the present invention is to use a magnetic liquid sealing device to achieve the sealing of the indoor end of the high-voltage AC / DC wall bushings.

[0018] Based on the above ideas, Figure 2As shown, in a basic embodiment, the high-voltage AC / DC wall bushing of the present invention includes a pipe body 1 and a central conductive rod 2 inside the pipe body 1, an indoor end of the pipe body 1 is provided with an end cover 3, the indoor end of the wall bushing includes a shielding cover 17, a magnetic liquid sealing device, a bellows 10 and a pressure equalizing ring 16, a cylindrical sealing section 4 is provided along the axial direction of the pipe body 1 on the side of the end cover 3 facing the pipe body 1, a magnetic liquid sealing device is provided inside the sealing section 4, the magnetic liquid seal has the advantages of sealing reliability, no leakage, no mechanical wear, long service life, high working efficiency, etc., and is suitable for static sealing and dynamic sealing, the magnetic liquid sealing device includes an annular permanent magnet 5, the permanent magnet 5 and the central conductive rod 2 maintain a gap for forming a rotating magnetic field loop, the permanent magnet 5 and the central conductive rod 2 do not contact each other, pole shoe rings 6 are provided on both sides of the permanent magnet 5, the permanent magnet 5, the pole shoe ring 6 and the central conductive rod 2 form a rotating magnetic field loop, a closed The magnetic field loop can effectively improve the utilization rate of the magnetic field and reduce the leakage magnetic loss, and can ensure that the magnetic lines of force are effectively utilized in the sealing gap, thereby improving the working efficiency of the permanent magnet. The inner diameter of the pole shoe ring 6 is larger than the outer diameter of the central conductive rod 2, so that there is a gap between the two for filling the magnetic liquid 15. A magnetic liquid 15 is arranged between the pole shoe ring 6 and the central conductive rod 2. Under the action of the rotating magnetic field loop, the magnetic liquid 15 is firmly adsorbed between the pole shoe ring 6 and the central conductive rod 2 to form an "O"-shaped ring, which completely blocks the gap to achieve a sealing effect. A cover plate 7 for clamping and fixing the magnetic liquid sealing device is arranged at one end of the sealing section 4 away from the end cover 3. There is no mechanical wear between the central conductive rod 2 and the magnetic liquid sealing device, which can reduce the generation of metal particles inside the wall bushing. At the same time, the dynamic sealing effect of the magnetic liquid sealing device is better than that of the sealing using the sealing ring 14, which is beneficial to enhancing the airtightness of the wall bushing.

[0019] In a preferred embodiment, a sealing ring 14 is arranged between the pole shoe ring 6 and the sealing section 4, and a groove for installing the sealing ring 14 is opened on the outer wall of the pole shoe ring 6. By installing the sealing ring 14, the static sealing performance of the magnetic liquid sealing device is enhanced to prevent the insulating gas inside the high-voltage AC and DC wall bushing from leaking through the gap between the pole shoe ring 6 and the sealing section 4.

[0020] In other embodiments, the sealing ring 14 may not be provided between the pole shoe ring 6 and the sealing segment 4. By improving the processing accuracy of the pole shoe ring 6 and the sealing segment 4, air leakage can be reduced. Although the static sealing effect is poor, it can still work normally.

[0021] In a preferred embodiment, an annular groove is provided on the inner wall of the pole shoe ring 6. In the rotating magnetic field loop formed by the permanent magnet 5, the pole shoe ring 6 and the center conductive rod 2, the magnetic field distribution in the gap between the pole shoe ring 6 and the center conductive rod 2 is relatively dispersed, the magnetic force exerted on the magnetic liquid is relatively small, and the magnetic liquid is relatively dispersed, which is not conducive to the sealing of the high-voltage AC and DC wall bushings. After the annular groove is opened, the rotating magnetic field loop concentrates the magnetic field along the pole shoe ring 6 at the tip of the annular groove in the gap between the pole shoe ring 6 and the center conductive rod 2, thereby ensuring the stability of the seal. In another embodiment, the inner wall of the pole shoe ring 6 is not provided with an annular groove, and stable sealing can also be achieved by enhancing the magnetic force of the permanent magnet 5, and normal operation can be achieved.

[0022] like Figure 1 As shown, in a preferred embodiment, the end cover 3 is fixedly installed with a bellows 10 facing away from the magnetic liquid sealing device, and a sealing plate 11 that can move axially along the tube body 1 is fixedly installed on the side of the bellows 10 away from the end cover 3, and the central conductive rod 2 is inserted into the sealing plate 11 and fixedly connected to the sealing plate 11. The central conductive rod 2 of the high-voltage AC and DC wall bushing is relatively long, which can easily cause the conductive rod to bend. During the flow of large current, the temperature of the central conductive rod 2 will change greatly. The deformation caused by temperature will cause the deflection value of the central conductive rod 2 to increase. The deformation of the central conductive rod 2 can be balanced by connecting one end of the central conductive rod 2 to the bellows 10.

[0023] In a preferred embodiment, a cylindrical guide section 12 is provided on the side of the sealing plate 11 facing the end cover 3 along the axial direction of the tube body 1, and a sealing ring 14 is installed on the guide section 12 to cooperate with the central conductive rod 2 to achieve a sealed fit between the central conductive rod 2 and the guide section 12. In other embodiments, the sealing ring 14 may not be provided, and the sealing may be achieved by the contact fit between the guide section 12 and the central conductive rod 2, which may also work normally.

[0024] In a preferred embodiment, a sleeve 8 for radial support is provided on the side of the pole shoe ring 6 away from the permanent magnet 5, and the sleeve 8 is used to limit the central conductive rod 2 to prevent radial runout during extension or transportation that affects the insulation effect. At the same time, the sleeve 8 can reduce the magnetic liquid 15 thrown out during reciprocating motion to avoid sealing failure. In other embodiments, although not providing the sleeve 8 will increase the loss of the magnetic liquid 15 and reduce the service life, it can still work normally.

[0025] In a preferred embodiment, a spacer 9 is provided between the sleeve 8 and the corresponding pole shoe ring 6. By providing the spacer 9, the magnetic liquid 15 can be prevented from adhering to the sleeve 8 due to the tension force and penetrating into the gap of the sleeve 8, resulting in the loss of the magnetic liquid 15 and reducing the service life of the magnetic liquid sealing device. In other embodiments, the spacer 9 is not provided, and the loss of the magnetic liquid 15 can be reduced by improving the processing accuracy, and normal operation can also be achieved.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A high voltage AC / DC wall bushing, comprising a tube body and a central conductive rod inside the tube body, wherein an end cap is provided at the indoor end of the tube body, characterized in that: A cylindrical sealing section is arranged along the axial direction of the tube body on the side of the end cover facing the tube body, and a magnetic liquid sealing device is arranged inside the sealing section. The magnetic liquid sealing device includes an annular permanent magnet, and the permanent magnet and the central conductive rod are kept at a distance for forming a rotating magnetic field loop. Pole shoe rings are arranged on both sides of the permanent magnet, and the outer wall of the pole shoe ring is tightly installed with the inner wall of the sealing section. The inner diameter of the pole shoe ring is larger than the outer diameter of the central conductive rod. Magnetic liquid is arranged between the pole shoe ring and the central conductive rod, and a cover plate for clamping and fixing the magnetic liquid sealing device is arranged at the end of the sealing section away from the end cover.

2. The high voltage AC / DC wall bushing according to claim 1, characterized in that: A sealing ring is arranged between the pole shoe ring and the sealing section.

3. The high voltage AC / DC wall bushing according to claim 1 or 2, characterized in that: The inner wall of the pole shoe ring is provided with an annular groove.

4. The high voltage AC / DC wall bushing according to claim 1 or 2, characterized in that: The end cover is fixedly mounted with a bellows on the side facing away from the magnetic liquid sealing device, and a sealing plate that can move axially along the tube body is fixedly mounted on the side of the bellows away from the end cover. The central conductive rod is inserted into the sealing plate and fixedly connected to the sealing plate.

5. The high voltage AC / DC wall bushing according to claim 4, characterized in that: A cylindrical guide section is arranged on one side of the sealing plate facing the end cover along the axial direction of the tube body, and a sealing ring matched with the central conductive rod is installed on the guide section.

6. The high voltage AC / DC wall bushing according to claim 1 or 2, characterized in that: A sleeve for radial support is arranged on the side of the pole shoe ring away from the permanent magnet.

7. The high voltage AC / DC wall bushing according to claim 6, characterized in that: A spacer is arranged between the sleeve and the corresponding pole shoe ring.

Images