Method and device for hoisting lower high-voltage bushing without removing upper bushing

Abstract

The application discloses a method and device for hoisting a lower high-voltage sleeve without dismounting an upper sleeve, and the method comprises the following steps: after a fault converter transformer is powered off and dismounted, the fault converter transformer is transported to a standby converter transformer site, and in the case that the upper high-voltage sleeve on the valve side of the converter transformer is not dismounted, the device is used to safely hoist the lower high-voltage sleeve. In the case that the upper high-voltage sleeve on the valve side is not dismounted, only a fixed limiting hoisting plate needs to be installed at the top end of the lower high-voltage sleeve, all lifting tools are connected to the hoisting plate, and then the hoisting plate is connected to the special lifting ring of the sleeve and the limiting hoisting plate through a tool U-shaped ring, the length of the lifting rope is changed through an adjusting hand-operated hoist, so that the corresponding inclination angle of the high-voltage sleeve is reached, and finally, the hoisting is completed by commanding a crane. The application does not need to expand the working range, so the workload is small, and the working efficiency is high. Especially, only the fault equipment is dismounted, so the healthy equipment is not affected.

Description

Technical Field

[0001] This invention belongs to the field of power maintenance and relates to the hoisting technology of the lower high-voltage bushing on the valve side of a converter transformer, especially the method and device for hoisting the lower high-voltage bushing without removing the upper high-voltage bushing on the valve side of the converter transformer. Background Technology

[0002] Converter transformers (CERTs) are one of the most important pieces of equipment in DC transmission systems, serving as the bridge connecting AC and DC power fields. Valve-side bushings are the most crucial accessory of CERTs. All work related to CERTs, such as accessory removal and installation, internal inspections, and bushing replacement, involves the installation and removal of valve-side bushings. The installation and removal of valve-side bushings is a lengthy and complex process. Traditional CERT valve-side bushing replacement and maintenance methods involve using cranes to lift and remove the bushings. However, this method suffers from poor precision in controlling the angle and position of insertion and removal, easily leading to incomplete installation or removal and creating safety hazards.

[0003] Due to structural, stress, and system requirements, the two high-voltage bushings on the valve side of each phase converter transformer are mostly designed to be vertically overlapping and inclined. Depending on the voltage level, the length, weight, inclination angle, and diameter of the high-voltage bushings of the converter transformer vary.

[0004] Currently, when a fault occurs in the lower high-voltage bushing on the valve side of a converter transformer, the only solution is to shut down the power, transport the faulty converter transformer to the backup converter transformer site, drain the oil, first remove the upper high-voltage bushing on the valve side, then repair or replace the lower high-voltage bushing, then restore the healthy upper high-voltage bushing on the valve side, and finally perform oil injection, hot oil circulation, settling, and testing. Traditional construction methods have the following main problems: 1. Unnecessary disassembly and assembly, posing safety hazards to healthy equipment. 2. High investment, large workload, and high labor intensity, resulting in low work efficiency. 3. Poor safety and civilized construction appearance. Therefore, a scientific and reasonable method must be adopted to safely hoist the lower high-voltage bushing on the valve side without removing the upper high-voltage bushing on the valve side. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and to provide a method and supporting device for efficiently, safely and conveniently hoisting the lower high-voltage bushing on the valve side of a converter transformer without removing the upper high-voltage bushing. This eliminates the need to remove the upper high-voltage bushing and completes the installation and removal of the lower bushing, achieving the effect of saving time, effort and labor.

[0006] Specifically, the present invention is implemented as follows:

[0007] A method for hoisting a lower high-voltage bushing without removing the upper bushing includes the following steps:

[0008] Step S1: Drain the insulating oil from the converter transformer, open the manhole of the converter transformer, enter the converter transformer and disconnect the primary connection wire of the high-voltage bushing.

[0009] Step S2: Install a fixed limiting plate (14) on the terminal block (15) at the top of the lower high-pressure bushing (5) on the valve side;

[0010] Step S3: Install and assemble the special lifting equipment. The crane hook is connected and fixed to the connecting plate (8) through the hook connecting strap, so that the connecting plate (8) is installed horizontally and the connecting plate (8) and the limiting plate (14) are close to each other. One side of the connecting plate (8) is connected to the lifting ring (2) of the valve side lower high-pressure bushing (5) through two lifting ring side straps (9). The other side of the connecting plate (8) is connected to one end of the hand chain hoist (11) through two upper hook straps (10). The other end of the hand chain hoist (11) is connected to the two ends of the limiting plate (14) through two lower hook straps (13). Tie two guy ropes (16) to the side of the valve side lower high-pressure bushing (5) facing the limiting plate (14) to control the valve side lower high-pressure bushing (5) from swinging too much during the hoisting process.

[0011] Step S4: Adjust the hoisting angle. Direct the crane and platform vehicle to cooperate and adjust the length of the sling by repeatedly trying to adjust the hand chain hoist (11) to achieve the tilt angle corresponding to the lower high-pressure bushing (5) on the valve side. Keep the sling (9) on the lifting ring side, the upper hook sling (10) of the hand chain hoist, and the lower hook sling (13) of the hand chain hoist in a state of uniform force.

[0012] Step S5: Direct the crane and platform vehicle to work together to complete the lifting and dismantling.

[0013] Furthermore, step S3 also includes: the limiting plate (14) extends laterally to both sides, and the length between the two ends is greater than the diameter of the upper high-pressure bushing (4) on the valve side. During the hoisting and disassembly process, the lifting ring side sling (9), the upper hook sling (10) of the hand chain hoist, and the lower hook sling (13) of the hand chain hoist are located on both sides of the upper high-pressure bushing (4) on the valve side and do not come into contact with it.

[0014] Furthermore, step S1 also includes: preparing the oil filter, oil tank, oil pipe, vacuum pump, dry air generator, testing instruments, crane, platform truck, fire-fighting equipment and facilities required for the converter transformer oil treatment before starting work, and arranging the site in advance, cleaning and connecting the pipes and containers, debugging the equipment and facilities, setting up the crane and platform truck, and draining the insulating oil in the converter transformer.

[0015] Furthermore, step S3 also includes: connecting the other two ends of the two connecting straps (7) hooked on the crane hook (6) to the hook strap connection holes (8-1) of the connecting plate (8) using tool U-rings.

[0016] In another aspect, the present invention provides a device for hoisting a lower high-pressure bushing without removing the upper bushing, comprising the following structure:

[0017] The connecting plate (8) is provided with several mounting holes. The mounting holes located at the top are connected to two connecting slings (7) and are connected to the crane hook (6) through the two connecting slings (7). The mounting holes located at the bottom are connected to two lifting ring side slings (9) and two hand chain hoist upper hook slings (10). The connecting plate (8) is used to bear the weight of the lower high-pressure bushing (5) on the valve side during the hoisting process and is connected to the crane hook.

[0018] The limiting lifting plate (14) is installed horizontally at the top outlet terminal block (15) of the lower high-pressure bushing (5) on the valve side. Each end is provided with a sling connection hole (17), which is connected to one end of the slings (13) of the two hand-operated hoists.

[0019] The hand chain hoist (11) includes an upper hook (12-1) and a lower hook (12-2). The upper hook (12-1) is connected to the other end of the upper hook sling (10), and the lower hook (12-2) is connected to the other end of the lower hook sling (13). The hand chain hoist (11) is used to adjust the length between the upper hook sling (10) and the lower hook sling (13), and can adjust the lifting angle of the lower hook sling (13).

[0020] The other end of the two lifting ring side straps (9) is installed on the lifting ring (2) at the tail end of the lower high-pressure bushing (5) on the valve side;

[0021] Guy ropes (16) are attached to the end of the lower high-pressure bushing (5) on the valve side that faces the limit plate (14) to control the lower high-pressure bushing (5) on the valve side from swinging too much during hoisting.

[0022] Furthermore, the limiting lifting plate (14) extends laterally to both sides, and the length between the two ends is greater than the diameter of the upper high-pressure bushing (4) on the valve side. During the hoisting and disassembly process, the lifting ring side sling (9), the upper hook sling (10) of the hand chain hoist, and the lower hook sling (13) of the hand chain hoist are located on both sides of the upper high-pressure bushing (4) on the valve side and do not come into contact with it.

[0023] Furthermore, the connecting plate (8) is rectangular in shape, and the mounting holes include a hook and strap connection hole (8-1) at each of the top two ends, a ring connection hole (8-2) at both ends of the bottom edge, and several adjustment holes next to the ring connection hole (8-2). The adjustment hole is a hook and strap connection hole (8-3) for a hand chain hoist.

[0024] Wherein: the hook and sling connection hole (8-1) is used to connect with the connecting sling (7);

[0025] The lifting ring connection hole (8-2) is used to connect to the upper end of the lifting ring side sling (9) via a tool U-ring; the hand chain hoist upper hook sling connection hole (8-3) is used to connect to the upper end of the hand chain hoist upper hook sling (10) via a tool U-ring; the adjustment hole can adjust the distance between the two hand chain hoist upper hook slings (10) by selecting the installation hole spacing.

[0026] Furthermore, the limiting hanging plate (14) has a symmetrical shape that is wide in the middle and narrow at both ends. The middle part is fitted onto the terminal block (15) at the top of the lower high-pressure bushing (5) on the valve side, and the sling connection hole (17) is opened at the two narrow ends respectively.

[0027] Furthermore, both the connecting hanging plate (8) and the limiting hanging plate (14) are arranged laterally and are nearly parallel to each other.

[0028] The working principle of the present invention is as follows: In the method of the present invention, through the design of the limiting lifting plate (14) and the connecting lifting plate (8), and the clever cooperation of the two lifting ring side slings (9) and the upper and lower hook slings of the hand chain hoist, the upper high-pressure bushing (4) on the valve side is positioned between the two lifting ring side slings (9) and between the two upper hook slings of the hand chain hoist, so as to realize the lifting of the lower high-pressure bushing (5) on the valve side from above the upper high-pressure bushing (4) without contacting the upper high-pressure bushing (4), and thus realize the direct connection of the crane to the lower high-pressure bushing (5) on the valve side. With the operation of the hand chain hoist 11, after the slings at both ends of the lower high-pressure bushing (5) on the valve side are subjected to the same force, the lower high-pressure bushing (5) on the valve side can be smoothly disassembled or installed by gradually moving it through the upper high-pressure bushing (4) on the valve side without touching it. The special structural design of the limiting hanging plate (14) and the connecting hanging plate (8) allows them to avoid the upper high-pressure bushing (4) on the valve side while achieving balanced force, thus achieving the effect of directly operating on the lower high-pressure bushing (5) on the valve side without first removing the upper high-pressure bushing (4).

[0029] The advantages of this invention compared to existing technologies are as follows: Because this invention enables the safe installation and removal of the lower high-voltage bushing on the valve side of the converter transformer without dismantling the upper high-voltage bushing, its advantages are significant: it reduces work steps, requires less investment, less workload, and less labor intensity compared to traditional technologies, thus greatly improving work efficiency; different sizes on the limit plate can accommodate various diameter valve-side high-voltage bushings; it eliminates unnecessary dismantling of intact equipment, thus eliminating potential safety hazards to the equipment caused by unnecessary dismantling operations in traditional methods; and the method of this invention exhibits better safety and civilized construction practices. Attached Figure Description

[0030] Figure 1 This is a front view of the structure of the device for hoisting a lower high-pressure bushing without removing the upper bushing according to the present invention;

[0031] Figure 2 This is a perspective view of the device structure for hoisting a lower high-pressure bushing without removing the upper bushing according to the present invention.

[0032] Figure 3 This is a schematic diagram of the device for hoisting the lower high-pressure bushing without removing the upper bushing according to the present invention;

[0033] Figure 4 A three-dimensional structural diagram of the connecting suspension plate;

[0034] Figure 5 This is a three-dimensional structural diagram of the limiting hanging plate;

[0035] Among them: lifting ring (2), upper high-pressure bushing on valve side (4), lower high-pressure bushing on valve side (5), crane hook (6), connecting sling (7), connecting plate (8), hook sling connection hole (8-1), lifting ring connection hole (8-2), upper hook sling connection hole of hand chain hoist (8-3), lifting ring side sling (9), upper hook sling of hand chain hoist (10), hand chain hoist (11), upper hook of hand chain hoist (12-1), lower hook of hand chain hoist (12-2), lower hook sling of hand chain hoist (13), limit plate (14), top outlet terminal wiring hole (15), guy rope (16), sling connection hole (17). Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0037] Example 1: The method for hoisting the lower high-voltage bushing without removing the upper bushing on the converter transformer side in this implementation case includes the following steps:

[0038] Step 1. Preparation and oil draining of the converter transformer.

[0039] Before starting work, prepare the necessary facilities and equipment for the converter transformer oil treatment, including oil filters, oil tanks, oil pipes, vacuum pumps, dry air generators, testing instruments, cranes, platform trucks, and fire-fighting equipment. The site must be arranged in advance, pipes and containers must be cleaned and connected, equipment and facilities must be debugged, and cranes and platform trucks must be set up to drain the insulating oil from the converter transformer.

[0040] Step 2. Open the manhole of the converter transformer and enter the converter transformer to disconnect the wires.

[0041] Open the maintenance manhole cover on the lower high-voltage bushing on the valve side and disconnect the primary connection line of the high-voltage bushing. Personnel entering the transformer must wear buttonless one-piece work clothes and high-top rubber boots, and tools must be protected against falling. During this process, all tools entering the transformer must be registered and strictly controlled to prevent them from being left inside the converter transformer.

[0042] Step 3. Install the fixed limit plate.

[0043] For the installation and fixing of the limit plate, see Figure 2 .

[0044] The limiting plate 15, which is made according to the parameters such as the wiring hole 15 at the top of the lower high-pressure bushing 5 on the valve side and the diameter of the lower high-pressure bushing 5 on the valve side, is installed and fixed on the wiring hole 15 at the top of the lower high-pressure bushing 5 on the valve side.

[0045] Step 4. Assemble the entire lifting gear, see Figure 1 .

[0046] First, connect the other two ends of the two connecting slings 7 that are hooked on the crane hook 6 to the hook sling connection holes 8-1 of the connecting plate 8 using tool U-rings; then connect one end of each of the two ring-side slings 9 to the ring connection holes 8-2 of the connecting plate 8 using tool U-rings, and connect the other two ends to the rings 2 of the lower high-pressure bushing 5 on the valve side using tool U-rings. Next, using a U-shaped tool, connect one end of each of the upper hook slings 10 of the two chain hoists to the connecting holes 8-3 of the chain hoist upper hook slings on the connecting plate 8. Hook the two upper hooks 12-1 of the chain hoists to the other ends of the upper hook slings 10. Then, hook one end of each of the lower hook slings 13 of the two chain hoists to the lower hooks 12-2 of the chain hoists. Use a U-shaped tool to connect the other ends of the lower hook slings 13 of the chain hoists to the connecting holes 17 at both ends of the limiting plate 14. Tie the two guy ropes 16 to the side of the lower high-pressure bushing 5 on the valve side facing the limiting plate 14 to control the lower high-pressure bushing 5 on the valve side from swinging too much during the hoisting process.

[0047] At this point, the entire lifting device assembly is complete.

[0048] Step 5. Adjust the hoisting angle.

[0049] The crane operator coordinated with the hoist, repeatedly adjusting the length of the sling on the hand chain hoist 11 to achieve the desired tilt angle corresponding to the high-voltage bushing. (See...) Figure 1 .

[0050] Step 6. Direct the crane and platform vehicle to work together to complete the lifting operation.

[0051] Step 7. Vacuuming, oil filling, hot oil circulation, settling, and testing of the converter transformer.

[0052] Example 2: A device for hoisting a lower high-voltage bushing without removing the upper bushing, comprising:

[0053] The connecting plate 8 is provided with several mounting holes. The mounting holes located at the top are connected to two connecting slings 7 and are connected to the crane hook 6 through the two connecting slings 7. The mounting holes located at the bottom are connected to two lifting ring side slings 9 and two hand chain hoist hook slings 10. The connecting plate 8 is used to bear the weight of the lower high-pressure bushing 5 on the valve side during the hoisting process and is connected to the crane hook.

[0054] The limiting lifting plate 14 is installed horizontally at the top outlet terminal hole 15 of the lower high-pressure bushing 5 on the valve side. Each end is provided with a sling connection hole 17, which is connected to one end of the sling of the hook 13 of the two hand chain hoists.

[0055] The hand chain hoist 11 includes an upper hook 12-1 and a lower hook 12-2. The upper hook 12-1 is connected to the other end of the upper hook sling 10, and the lower hook 12-2 is connected to the other end of the lower hook sling 13. The hand chain hoist 11 is used to adjust the length between the upper hook sling 10 and the lower hook sling 13, and can adjust the lifting angle of the lower hook sling 13.

[0056] The other end of the two lifting straps 9 is installed on the lifting ring 2 at the tail end of the lower high-pressure bushing 5 on the valve side;

[0057] Guy ropes 16 are attached to the end of the lower high-pressure bushing 5 on the valve side that faces the limit plate 14, and are used to control the lower high-pressure bushing 5 on the valve side to prevent large swings during hoisting.

[0058] Preferably, the limiting lifting plate 14 extends laterally to both ends, and the length between the two ends is greater than the diameter of the upper high-pressure bushing 4 on the valve side. During hoisting and disassembly, the lifting ring side sling 9, the upper hook sling 10 of the hand chain hoist, and the lower hook sling 13 of the hand chain hoist are located on both sides of the upper high-pressure bushing 4 on the valve side and do not come into contact with it. The limiting lifting plate 14 should be kept horizontal as much as possible during use, and the upper hook sling 10 of the hand chain hoist and the lifting ring side sling 9 at both ends should be kept in balance. The limiting lifting plate 14 should be evenly stressed, and the hand chain hoist should be used for leveling operations when necessary to adjust the force balance.

[0059] Preferably, the connecting plate 8 is rectangular in shape, and the mounting holes include hook and strap connection holes 8-1 at both ends of the top, ring connection holes 8-2 at both ends of the bottom edge, and several adjustment holes next to the ring connection holes 8-2. The adjustment holes are hook and strap connection holes 8-3 of the hand chain hoist. In actual use, the length of the connecting plate 8 needs to be matched with the actual site dimensions so that its center and the center of gravity of the entire hoisting equipment are on the same vertical line. This ensures that the hook and strap connection holes 8-1, ring connection holes 8-2, and adjustment holes are all arranged symmetrically at the center of gravity, maintaining the overall stability during hoisting. Wherein: hook sling connection hole 8-1 is used to connect with the connecting sling 7; ring connection hole 8-2 is used to connect with the upper end of the ring-side sling 9 via a tool U-shaped ring; hook sling connection hole 8-3 is used to connect with the upper end of the hook sling 10 of the hand chain hoist via a tool U-shaped ring; the adjustment hole can adjust the distance between the two hook slings 10 of the hand chain hoist by selecting the spacing of the installation holes.

[0060] Preferably, the limiting lifting plate 14 has a symmetrical shape, wider in the middle and narrower at both ends. The middle part is fitted onto the terminal block 15 at the top of the lower high-pressure bushing 5 on the valve side, and the lifting strap connection holes 17 are respectively opened at the two narrow ends. This structure helps the limiting lifting plate 14 maintain force balance during hoisting. Both the connecting lifting plate 8 and the limiting lifting plate 14 are arranged laterally and are nearly parallel to each other.

[0061] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for hoisting a lower high-voltage bushing without removing the upper bushing, characterized in that... Includes the following steps: Step S1: Drain the insulating oil from the converter transformer, open the manhole of the converter transformer, enter the converter transformer and disconnect the primary connection wire of the high-voltage bushing. Step S2: The limiting plate (14) is installed horizontally at the top outlet terminal block (15) of the lower high-pressure bushing (5) on the valve side. Each end is provided with a sling connection hole (17), which is connected to one end of the slings (13) of the two hand chain hoists. Step S3: The connecting plate (8) has several mounting holes. The upper mounting hole is connected to two connecting slings (7) and is connected to the crane hook (6) through the two connecting slings (7). The lower mounting hole is connected to two lifting ring side slings (9) and two hand chain hoist upper hook slings (10). The connecting plate (8) is used to bear the weight of the lower high-pressure bushing (5) on the valve side during the hoisting process and is connected to the crane hook. The connecting plate (8) is installed horizontally, and the connecting plate (8) and the limiting plate (14) are close to each other. One side of the connecting plate (8) is connected to the lifting ring (2) of the lower high-pressure bushing (5) on the valve side through two lifting ring side slings (9). The other side of the connecting plate (8) is connected to one end of the hand chain hoist (11) through two hand chain hoist upper hook slings (10). 1) The other end is connected to the two ends of the limiting plate (14) by two hand-operated hoist hooks (13); two guy ropes (16) are respectively tied to the side of the lower high-pressure bushing (5) on the valve side facing the limiting plate (14) to control the lower high-pressure bushing (5) on the valve side to prevent large swings during hoisting; the hand-operated hoist (11) includes the upper hook (12-1) and the lower hook. (12-2), the upper hook (12-1) of the hand chain hoist is connected to the other end of the upper hook sling (10) of the hand chain hoist, and the lower hook (12-2) of the hand chain hoist is connected to the other end of the lower hook sling (13) of the hand chain hoist. The hand chain hoist (11) is used to adjust the length between the upper hook sling (10) and the lower hook sling (13) of the hand chain hoist, and can adjust the lifting angle of the lower hook sling (13). Step S4: Adjust the hoisting angle. Direct the crane and platform vehicle to cooperate and adjust the length of the sling by repeatedly trying to adjust the hand chain hoist (11) to achieve the tilt angle corresponding to the lower high-pressure bushing (5) on the valve side. Keep the sling (9) on the lifting ring side, the upper sling (10) on the hand chain hoist, and the lower sling (13) on the hand chain hoist in a state of uniform force. Step S5: Direct the crane and platform vehicle to work together to complete the lifting and dismantling.

2. The method for hoisting a lower high-voltage bushing without removing the upper bushing according to claim 1, characterized in that, The step S3 also includes: the limiting plate (14) extends laterally to both sides, and the length between the two ends is greater than the diameter of the upper high-pressure bushing (4) on the valve side. During the hoisting and disassembly process, the lifting ring side sling (9), the upper hook sling (10) of the hand chain hoist, and the lower hook sling (13) of the hand chain hoist are located on both sides of the upper high-pressure bushing (4) on the valve side and do not come into contact with it.

3. The method for hoisting a lower high-voltage bushing without removing the upper bushing according to claim 1, characterized in that, Step S1 also includes: preparing the oil filter, oil tank, oil pipe, vacuum pump, dry air generator, test instruments, crane, platform truck, fire-fighting equipment and facilities required for the converter transformer oil treatment before starting work, and arranging the site in advance, cleaning and connecting the pipes and containers, debugging the equipment and facilities, and setting up the crane and platform truck.

4. The method for hoisting a lower high-voltage bushing without removing the upper bushing according to claim 1, characterized in that, Step S3 further includes: connecting the other two ends of the two connecting straps (7) hooked on the crane hook (6) to the hook strap connection holes (8-1) of the connecting plate (8) using tool U-rings.

5. The method for hoisting a lower high-voltage bushing without removing the upper bushing according to claim 1, characterized in that, The connecting plate (8) is rectangular in shape. The mounting holes include hook and strap connection holes (8-1) located at both ends of the top, ring connection holes (8-2) located at both ends of the bottom edge, and several adjustment holes located next to the ring connection holes (8-2). The adjustment holes are hook and strap connection holes (8-3) of the hand chain hoist. Wherein: the hook and sling connection hole (8-1) is used to connect with the connecting sling (7); The lifting ring connection hole (8-2) is used to connect to the upper end of the lifting ring side strap (9) via a tool U-ring; The hook sling connection hole (8-3) of the hand chain hoist is used to connect to the upper end of the hook sling (10) of the hand chain hoist via a tool U-shaped ring; The adjustment hole can be used to adjust the distance between the hook straps (10) of the two hand chain hoists by selecting the spacing between the installation holes.

6. The method for hoisting a lower high-voltage bushing without removing the upper bushing according to claim 1, characterized in that, The limiting plate (14) has a symmetrical shape that is wide in the middle and narrow at both ends. The middle part is fitted onto the terminal block (15) at the top of the lower high-pressure bushing (5) on the valve side. The sling connection holes (17) are respectively opened at the two narrow ends.

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