A tap changer leading device with double ring connection structure

Abstract

This invention discloses a tap changer lead-out device with a double-ring connection structure, relating to the field of transformer voltage regulation technology. It includes an oil chamber; an insulated rotating shaft vertically disposed inside the oil chamber, its upper end being drively connected to the output end of a fast switching mechanism, and its lower end supported on the bottom of the cylinder by a bearing; and at least one lead-out device, which is a bimetallic composite ring composed of an aluminum outer ring and a copper inner ring. The aluminum outer ring is fixedly installed on the inner wall of the insulating cylinder of the oil chamber, and a boss is machined on its upper end face. The copper inner ring is fixedly embedded in the inner wall of the aluminum outer ring through a heat-fitting process. This invention, through the bimetallic structure of the aluminum outer ring and the copper inner ring heat-fitting composite, solves the problems of easy deformation during the machining of pure copper lead-out rings and difficulty in ensuring the positional accuracy of the boss, thus ensuring three-phase synchronization.

Description

Technical Field

[0001] This invention relates to the field of transformer voltage regulation technology, and more specifically to a tap changer lead-out device with a double-ring connection structure. Background Technology

[0002] On-load tap changers are key components for voltage regulation of transformers under load. In composite vacuum on-load tap changers (such as CKV type, CKVV type, etc.), multiple lead-out rings (also known as conductive rings) are fixedly installed on the inner wall of the oil chamber. These lead-out rings serve two purposes: firstly, they act as terminals connecting to the taps of the transformer's regulating windings, carrying the operating current; secondly, the upper or lower end faces of the lead-out rings are usually machined with bosses of a specific profile, which cooperate with the drive lever rollers on the switching spindle to precisely control the opening and closing sequence of the vacuum interrupter and the switching contacts, thereby ensuring the correct execution of the switching procedure.

[0003] In existing technologies, the aforementioned lead-out rings typically employ an integral pure copper structure. Copper material possesses excellent electrical conductivity, meeting current-carrying requirements. However, during on-site production and long-term operation and maintenance, the inventors have discovered that the aforementioned integral pure copper lead-out rings suffer from several drawbacks in actual manufacturing and assembly. Copper is relatively soft, and when multiple high-precision bosses need to be machined on the lead-out ring, the cutting stress generated during machining easily causes deformation of the inner and outer diameters of the ring-shaped workpiece. Once the deformation exceeds the allowable limit, the relative positional accuracy between the bosses cannot be guaranteed, leading to inaccurate contact between the lead-out ring and the mounting reference surface of the oil chamber insulation cylinder. In actual three-phase switches, multiple lead-out rings are installed at different heights. Any deviation in the boss position of any lead-out ring will directly cause asynchrony in the three-phase switching action, i.e., inconsistent opening sequence of the vacuum interrupters in phases A, B, and C. This can range from minor issues like abnormal switching waveforms and burnt-out transition resistors to more serious problems such as phase-to-phase short circuits or switching failures. Summary of the Invention

[0004] The purpose of this invention is to provide a tap changer lead-out device with a double-ring connection structure to solve the technical problems in the prior art, such as easy deformation during processing, difficulty in ensuring the positional accuracy of the boss, and poor three-phase synchronization caused by the use of a pure copper integral structure for the tap changer lead-out ring.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a tap changer lead-out device with a double-ring connection structure, comprising an oil chamber, wherein the oil chamber is a vertically arranged cylindrical sealed container, which is enclosed by a head flange, a middle flange and a bottom of the cylinder;

[0006] A head cover is sealed and fixed to the upper end face of the head flange;

[0007] A quick-switching mechanism is installed within the receiving space formed between the head cover and the head flange;

[0008] An insulated rotating shaft is vertically installed inside the oil chamber. Its upper end is connected to the output end of the quick switching mechanism, and its lower end is supported on the bottom of the cylinder by a bearing.

[0009] And at least one lead-out device, the lead-out device being a bimetallic composite ring consisting of an aluminum outer ring and a copper inner ring;

[0010] The aluminum outer ring is fixedly installed on the inner wall of the insulating cylinder of the oil chamber, and a boss is machined on the upper end face of the aluminum outer ring.

[0011] The copper inner ring is fixedly embedded in the inner wall of the aluminum outer ring by a heat fitting process. The copper inner ring is provided with a terminal block, and the inner wall of the copper inner ring is used to slide in contact with the lead-out moving contact.

[0012] The insulating shaft passes through the center of the copper inner ring and maintains a radial gap with the inner wall of the copper inner ring.

[0013] Furthermore, the copper inner ring is located below the boss portion and near the bottom of the aluminum outer ring, and the interference fit between the aluminum outer ring and the copper inner ring is 0.1% to 0.3% of the mating diameter.

[0014] Furthermore, the boss portion is integrally formed with the aluminum outer ring body, and the boss portion is circumferentially distributed along the upper end surface of the aluminum outer ring body.

[0015] Furthermore, a drive lever is installed on the insulating shaft, and a roller is provided at one end of the drive lever. The roller rolls and fits against the boss portion of the aluminum outer ring. The lead-out moving contact is installed on the insulating shaft.

[0016] Furthermore, a copper-tungsten moving contact and a pure copper main contact are also installed on the insulated rotating shaft. The copper-tungsten moving contact slides in contact with the copper-tungsten stationary contact on the inner wall of the oil chamber, and the pure copper main contact slides in contact with the main stationary contact on the inner wall of the oil chamber.

[0017] Furthermore, the insulating shaft is provided with three vacuum tubes, which are arranged at 120° intervals along the circumferential direction;

[0018] The stationary end of each vacuum tube is fixed to the upper or lower bracket of the insulating shaft by a vacuum tube fixed end mounting plate.

[0019] The moving end of each vacuum tube is connected to the other end of a drive lever via a vacuum tube moving end mounting plate. The roller on the drive lever rolls against the boss of the aluminum outer ring to drive the vacuum tube to open and close in a predetermined sequence.

[0020] Furthermore, a polarity converter is also provided at the lower part of the insulating shaft. The polarity converter is located inside the oil chamber. The moving contact of the polarity converter rotates with the insulating shaft and cooperates with the polarity conversion stationary contact fixed on the bottom of the cylinder.

[0021] Furthermore, a shielding cover is also provided on the insulating shaft. The shielding cover has a multi-layer structure and is located above and below the vacuum tube, respectively, to balance the electric field and protect the vacuum tube from external electric field interference.

[0022] Furthermore, the drive lever is hinged to a sector-shaped metal bracket on the insulating shaft. When the insulating shaft rotates, the roller rolls along the boss portion, thereby driving the drive lever to swing and causing the moving end of the vacuum tube to move.

[0023] Compared with existing technologies, the present invention provides a tap changer lead-out device with a double-ring connection structure. By designing the lead-out device as a bimetallic structure of an aluminum outer ring and a copper inner ring thermally fitted together, the mechanical and electrical functions are separated. The aluminum outer ring undertakes the functions of installation positioning and cam surface driving. Since the machinability of aluminum alloy is better than that of pure copper, stress deformation is less likely to occur when machining the cam surface bosses, which can accurately ensure the relative position and contour accuracy of each boss. This solves the problem of difficulty in ensuring the positional accuracy of the bosses caused by the softness and easy deformation during machining of pure copper integral lead-out rings.

[0024] Secondly, due to the guaranteed machining precision of the aluminum outer ring, the positional relationship between its mounting reference surface and cam surface is precisely controllable. After multiple lead-out devices are arranged at intervals along the axial direction of the oil chamber insulation cylinder, the circumferential phase angle of each cam surface can be strictly distributed according to the design value, ensuring the synchronicity of the three-phase switching mechanism's operation, avoiding switching sequence disorder caused by boss position deviation, and improving the reliability of switch operation.

[0025] Secondly, the copper inner ring is specifically designed to carry the operating current, exhibiting excellent conductivity; the aluminum outer ring does not bear the primary current-carrying task, and its material cost is lower than that of pure copper while also being lighter in weight. The thermoforming interference fit allows the two to form a tight mechanical bond and good electrical contact at room temperature, ensuring the reliability of the current path, reducing material costs and overall weight, and simplifying the manufacturing process. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0027] Figure 1 This is a schematic diagram of the overall structure of the tap changer lead-out device with a double-ring connection structure provided in an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the overall structure of the insulating cylinder provided in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the overall internal component structure of the insulating cylinder provided in an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the copper inner ring and aluminum outer ring components provided in an embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1. Oil chamber; 2. Head flange; 3. Intermediate flange; 4. Bottom of cylinder; 5. Head cover; 6. Insulating shaft; 7. Aluminum outer ring; 701. Boss; 8. Copper inner ring; 9. Terminal block; 10. Lead-out moving contact; 11. Drive lever; 12. Copper-tungsten moving contact; 13. Pure copper main contact; 14. Vacuum tube; 15. Vacuum tube fixed end mounting plate; 16. Vacuum tube moving end mounting plate; 17. Polarity converter; 18. Shielding cover; 19. Insulating cylinder; 20. Copper-tungsten stationary contact. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] As attached Figure 1 To be continued Figure 4 As shown:

[0035] Example 1:

[0036] This invention provides a tap changer lead-out device with a double-ring connection structure, including an oil chamber 1, which is a vertically arranged cylindrical sealed container surrounded by a head flange 2, an intermediate flange 3, and a bottom 4. A cover 5 is sealed and fixed to the upper end face of the head flange 2. A quick-switching mechanism (not shown in the figure) is installed in the receiving space formed between the cover 5 and the head flange 2.

[0037] An insulated rotating shaft 6 is vertically installed inside the oil chamber 1. Its upper end is connected to the output end of the quick-switching mechanism, and its lower end is supported on the bottom of the cylinder 4 by a bearing. The quick-switching mechanism is a spring-energy-storage mechanism. When it receives an operation command, it instantly releases energy to drive the insulated rotating shaft 6 to rotate by a fixed angle, thereby switching from one tap position to an adjacent tap position.

[0038] Structure of the extraction device:

[0039] The oil chamber 1 is equipped with an insulating cylinder 19, and at least one lead-out device is fixedly installed on the inner wall of the insulating cylinder 19. In this embodiment, multiple lead-out devices are arranged at intervals along the axial direction of the insulating cylinder 19, corresponding to different tap positions of the transformer.

[0040] The lead-out device is a bimetallic composite ring, consisting of an aluminum outer ring 7 and a copper inner ring 8.

[0041] The aluminum outer ring 7 is made of 6061 aluminum alloy or ZL101 cast aluminum material, and its outer wall is provided with multiple mounting lugs (not shown in the figure), which are fixed to the inner wall of the insulating cylinder 19 of the oil chamber 1 by bolts. The upper end face of the aluminum outer ring 7 is machined with a boss 701, which is integrally formed with the aluminum outer ring 7 and is distributed circumferentially along the upper end face of the aluminum outer ring 7. The boss 701 is composed of multiple bosses of different heights, which together form a cam surface with a specific contour curve for controlling the switching sequence.

[0042] The inner copper ring 8 is made of T2 copper. It is located below the boss 701 and near the bottom of the outer aluminum ring 7. The inner copper ring 8 is fixedly fitted to the inner wall of the outer aluminum ring 7 using a heat-shrink process with an interference fit. Specifically, the outer aluminum ring 7 is heated to 180°C–220°C, causing its inner diameter to increase due to thermal expansion. Then, the inner copper ring 8, at room temperature, is fitted into the inner cavity of the outer aluminum ring 7. After natural cooling, a tight interference fit is formed. The interference between the outer aluminum ring 7 and the inner copper ring 8 is 0.1%–0.3% of the fitting diameter.

[0043] The copper inner ring 8 is provided with terminals 9, which are multiple threaded holes on the inner wall of the copper inner ring 8, for connecting the tap wires led out from the transformer by tightening with bolts. The inner wall of the copper inner ring 8 is also used for sliding contact with the lead-out moving contact 10 to lead out the working current.

[0044] The insulating shaft 6 passes through the center of the copper inner ring 8 and maintains a radial gap with the inner wall of the copper inner ring 8 to ensure that the insulating shaft 6 rotates without friction or jamming.

[0045] Related components on the insulated shaft 6:

[0046] A drive lever 11 is mounted on the insulating shaft 6. One end of the drive lever 11 is equipped with a roller, which rolls in contact with the boss 701 of the aluminum outer ring 7. The lead-out moving contact 10 is also mounted on the insulating shaft 6 and maintains sliding contact with the inner wall of the copper inner ring 8. When the insulating shaft 6 rotates, the lead-out moving contact 10 is always in contact with the inner wall of the copper inner ring 8, drawing current from the rotating shaft to the stationary copper inner ring 8, and then transmitting it to the transformer winding through the terminal 9.

[0047] The insulated rotating shaft 6 is also equipped with a copper-tungsten moving contact 12 and a pure copper main contact 13. The copper-tungsten moving contact 12 is in sliding contact with the copper-tungsten stationary contact 20 on the inner wall of the oil chamber 1, and is used to interrupt the current during switching; the pure copper main contact 13 is in sliding contact with the main stationary contact on the inner wall of the oil chamber 1, and is used to carry the working current for a long time.

[0048] Vacuum tube 14 and drive timing:

[0049] Three vacuum tubes 14 are mounted on the insulating shaft 6, and the three vacuum tubes 14 are arranged at 120° intervals along the circumference. The stationary end of each vacuum tube 14 is fixed to the upper or lower bracket of the insulating shaft 6 by a vacuum tube fixed end mounting plate 15. The moving end of each vacuum tube 14 is connected to the other end of a drive lever 11 by a vacuum tube moving end mounting plate 16. The roller on the drive lever 11 rolls in contact with the boss 701 of the aluminum outer ring 7.

[0050] During operation, as the insulated shaft 6 rotates, the roller rolls along the contour curve of the boss portion 701. During the disconnection process, the roller first moves along the lifting motion of the boss portion 701, driving the lever 11 to swing and causing the moving end of the vacuum tube 14 to move, thus disconnecting the vacuum tube 14 first and cutting off the load current (the arc is extinguished within the vacuum tube 14). Subsequently, the copper-tungsten moving contact 12 separates from the copper-tungsten stationary contact 20; since the current has been cut off at this time, no arc is generated between them. During the connection process, the copper-tungsten moving contact 12 first closes with the copper-tungsten stationary contact 20 at the target position. Then, the roller enters the return section of the boss portion 701, driving the lever 11 to move in the opposite direction, causing the vacuum tube 14 to close and connecting the current. Finally, the pure copper main contact 13 closes with the main stationary contact, undertaking the long-term current-carrying task. Through the above timing control, arc-free switching of the load current by the vacuum tube 14 is achieved.

[0051] Polarity converter 17 and shield 18:

[0052] A polarity converter 17 is also provided at the lower part of the insulating shaft 6, and the polarity converter 17 is located inside the oil chamber 1. The moving contact of the polarity converter 17 rotates with the insulating shaft 6 and cooperates with the polarity conversion stationary contact fixed on the bottom of the cylinder 4 to realize the forward and reverse adjustment or coarse and fine adjustment function of the voltage regulating winding.

[0053] The insulating shaft 6 is also provided with a shield 18, which has a multi-layer structure and is located above and below the vacuum tube 14, respectively, to balance the electric field, protect the vacuum tube 14 from external electric field interference, and improve insulation performance.

[0054] Brief description of the work process:

[0055] When the transformer requires voltage regulation, the rapid switching mechanism drives the insulated shaft 6 to rotate. The insulated shaft 6 drives the drive lever 11, the lead-out moving contact 10, the copper-tungsten moving contact 12, the pure copper main contact 13, the vacuum tube 14, and the polarity converter 17 to rotate together. During rotation, the roller of the drive lever 11 rolls along the boss 701 of the aluminum outer ring 7, controlling the opening and closing of the vacuum tube 14 according to a predetermined sequence, realizing a smooth switching from the current tap position to the next tap position. The operating current flows from the transformer winding through the conductor into the terminal 9 of the copper inner ring 8, then through the copper inner ring 8 and the lead-out moving contact 10 into the conductive circuit on the insulated shaft 6, and finally outputs to the load through the pure copper main contact 13 and the main stationary contact.

[0056] Example 2:

[0057] This embodiment has the same basic structure as Embodiment 1, but differs in the following aspects.

[0058] In this embodiment, a positioning key (not shown in the figure) is also provided on the outer wall of the aluminum outer ring 7, and a keyway matching the positioning key is provided on the inner wall of the insulating cylinder 19 of the oil chamber 1. Through the cooperation of the positioning key and the keyway, the aluminum outer ring 7 is precisely positioned circumferentially on the inner wall of the insulating cylinder 19, ensuring higher phase angle consistency of the bosses 701 among multiple lead-out devices, and further improving the three-phase synchronization accuracy.

[0059] The upper end face of the copper inner ring 8 extends radially outward to form a protruding current-carrying ring edge. The terminal 9 is disposed on the current-carrying ring edge, rather than on the inner wall. This structure facilitates the connection of wires from the side and is suitable for applications with limited installation space.

[0060] The shield 18 is fixed to the insulating shaft 6 by an insulating support, rather than being directly sleeved on the insulating shaft 6, in order to reduce the influence of the shield 18 on the rotational inertia of the insulating shaft 6, and is suitable for switches with higher speed requirements.

[0061] The drive lever 11 is hinged at its center to a sector-shaped metal bracket on the insulating shaft 6. One end of the drive lever 11 is connected to the moving end mounting plate 16 of the vacuum tube, and the other end is fitted with a roller. When the insulating shaft 6 rotates, the roller rolls along the boss 701, and the drive lever 11 swings around the hinge point, thereby driving the moving end of the vacuum tube 14 to move. This hinged connection makes the movement of the drive lever 11 smoother and the transmission efficiency higher.

[0062] The other structures, connections, and working principles of this embodiment are the same as those of Embodiment 1, and will not be repeated here.

[0063] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A tap changer lead-out device with a double-ring connection structure, characterized in that, include: An oil chamber (1) is a vertically arranged cylindrical sealed container, which is surrounded by a head flange (2), a middle flange (3) and a bottom (4); An insulating cylinder (19) is disposed inside the oil chamber (1); A head cover (5) is sealed and fixed to the upper end face of the head flange (2); A quick-change mechanism is installed in the receiving space formed between the head cover (5) and the head flange (2); An insulated rotating shaft (6) is vertically installed inside the oil chamber (1), with its upper end connected to the output end of the quick switching mechanism and its lower end supported on the bottom of the cylinder (4) by a bearing; And at least one lead-out device, the lead-out device being a bimetallic composite ring consisting of an aluminum outer ring (7) and a copper inner ring (8); The aluminum outer ring (7) is fixedly installed on the inner wall of the insulating cylinder (19) of the oil chamber (1), and the upper end face of the aluminum outer ring (7) is machined with a boss (701). The copper inner ring (8) is fixedly embedded in the inner wall of the aluminum outer ring (7) by heat fitting process. The copper inner ring (8) is provided with a terminal (9). The inner wall of the copper inner ring (8) is used to slide in contact with the lead-out moving contact (10). The insulating shaft (6) passes through the center of the copper inner ring (8) and maintains a radial gap with the inner wall of the copper inner ring (8).

2. The tap changer lead-out device with a double-ring connection structure according to claim 1, characterized in that, The copper inner ring (8) is located below the boss (701) and near the bottom of the aluminum outer ring (7). The interference between the aluminum outer ring (7) and the copper inner ring (8) is 0.1% to 0.3% of the mating diameter.

3. The tap changer lead-out device with a double-ring connection structure according to claim 1, characterized in that, The boss (701) is integrally formed with the aluminum outer ring (7), and the boss (701) is circumferentially distributed along the upper end face of the aluminum outer ring (7).

4. The tap changer lead-out device with a double-ring connection structure according to claim 1, characterized in that, A drive lever (11) is installed on the insulating shaft (6). A roller is provided at one end of the drive lever (11). The roller rolls against the boss (701) of the aluminum outer ring (7). The lead-out moving contact (10) is installed on the insulating shaft (6).

5. A tap changer lead-out device with a double-ring connection structure according to claim 4, characterized in that, The insulating shaft (6) is also equipped with a copper-tungsten moving contact (12) and a pure copper main contact (13). The copper-tungsten moving contact (12) slides in contact with the copper-tungsten stationary contact (20) on the inner wall of the oil chamber (1), and the pure copper main contact (13) slides in contact with the main stationary contact on the inner wall of the oil chamber (1).

6. A tap changer lead-out device with a double-ring connection structure according to claim 5, characterized in that, The insulating shaft (6) is provided with three vacuum tubes (14), which are arranged at 120° intervals along the circumferential direction. The stationary end of each vacuum tube (14) is fixed to the upper or lower bracket of the insulating shaft (6) by means of a vacuum tube fixed end mounting plate (15); The moving end of each vacuum tube (14) is connected to the other end of a drive lever (11) via a vacuum tube moving end mounting plate (16). The roller on the drive lever (11) rolls against the boss (701) of the aluminum outer ring body (7) to drive the vacuum tube (14) to open and close in a predetermined sequence.

7. A tap changer lead-out device with a double-ring connection structure according to claim 6, characterized in that, A polarity converter (17) is also provided at the lower part of the insulating shaft (6). The polarity converter (17) is located inside the oil chamber (1). The moving contact of the polarity converter (17) rotates with the insulating shaft (6) and cooperates with the polarity conversion stationary contact fixed on the bottom of the cylinder (4).

8. A tap changer lead-out device with a double-ring connection structure according to claim 7, characterized in that, The insulating shaft (6) is also provided with a shield (18), which is a multi-layer structure and is located above and below the vacuum tube (14) respectively, to balance the electric field and protect the vacuum tube (14) from external electric field interference.

9. A tap changer lead-out device with a double-ring connection structure according to claim 6, characterized in that, The drive lever (11) is hinged to the fan-shaped metal bracket on the insulating shaft (6). When the insulating shaft (6) rotates, the roller rolls along the boss (701), thereby driving the drive lever (11) to swing and causing the moving end of the vacuum tube (14) to move.

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