A pole-mounted transformer platform 10kV line gapless surge arrester and method

Abstract

The application belongs to the field of lightning arresters, and particularly relates to a gapless lightning arrester for a 10kV line of a pole-mounted transformer and a method. The application solves a series of problems in the prior art, such as inconvenient assembly, high cost, and the need to improve lightning protection performance. The gapless lightning arrester provided by the application comprises a mounting bracket, a lightning arrester body, a connecting wire, a magnetic suction plug terminal, and a magnetic suction socket terminal. The lightning arrester body is fixed on the mounting bracket, the connecting wire connects the lightning arrester body and the magnetic suction plug terminal, and the magnetic suction plug terminal is connected with the magnetic suction socket terminal in a plug-in manner. The application further provides an installation scheme, in which the lightning arrester is installed in parallel with a high-voltage side bushing of a distribution transformer to be protected, so that the lightning protection performance is greatly improved. The application has a simple structure, low cost, and is convenient to assemble and disassemble, and is suitable for large-scale application. The installation scheme of the gapless lightning arrester can significantly improve the lightning protection performance of the lightning arrester.

Description

Technical Field

[0001] This invention belongs to the field of surge arresters, and specifically relates to a gapless surge arrester and method for a 10kV line on a pole-mounted transformer. Background Technology

[0002] 10kV overhead distribution lines distribute electricity to low-voltage users by T-connecting down leads on the conductors and stepping down the voltage through a 10kV / 0.4kV distribution transformer on a pole-mounted transformer platform. Chinese technical standards GB / T 50064-2014 "Code for Overvoltage Protection and Insulation Coordination Design of AC Electrical Installations" and GB 51302-2018 "Design Standard for Overhead Insulated Distribution Lines" both stipulate that a set of gapless metal oxide surge arresters with a rated voltage of 17kV should be installed on the 10kV side of the distribution transformer for lightning protection to reduce the probability of lightning overvoltages entering the transformer winding coils and causing insulation damage.

[0003] According to the regulations of the State Grid Corporation of China and China Southern Power Grid Co., Ltd., the general type of gapless surge arrester is a composite insulated jacket gapless metal oxide surge arrester. The installation method is as follows: the surge arrester is installed on the T-junction down conductor segment between the fuse and the high-voltage side bushing of the distribution transformer. The high-voltage end of the surge arrester is fastened to one end of the metal connecting wire, and the other end of the metal connecting wire is hinged to the T-junction down conductor with the core wire exposed after a small section of insulation layer has been peeled off. The insulation layer is then restored by wrapping with insulating tape. The low-voltage end of the surge arrester is installed on a metal crossarm set on the transformer support pole.

[0004] While general-purpose surge arresters have fewer components and a simpler structure, they also have significant drawbacks. If a surge arrester malfunctions due to manufacturing defects, high-amplitude lightning strikes in the vicinity, or external damage, it cannot be disassembled while energized, making it impossible to replace it with a new one. For arrests affecting power supply, immediate power outages are necessary for repairs, which expands the scope of the fault, increases economic losses during maintenance, and reduces power supply reliability. For arrests not affecting power supply, replacement can wait until the maintenance outage window, but before that, the distribution transformer lacks lightning protection and is left unprotected, posing a high risk. Furthermore, sampling and testing of operating surge arresters is the most direct and economical way to assess their operational status; however, due to the inability to disassemble and sample existing arresters while energized, there is usually no process monitoring, meaning that most surge arresters are in an "out-of-control" state after being connected to the grid until they fail.

[0005] Patents CN202010413326.2, CN202220856061.8, and CN201820155862.5 all propose a novel gapless surge arrester for 10kV lines, which can be used on pole-mounted transformer platforms. These surge arresters, designed with complex support and fixing components or based on the structural principles of 10kV line fuses, can achieve the ultimate goal of live removal and replacement. However, their overly complex structure and numerous components lead to several new problems: First, assembly and on-site installation are inconvenient; second, the large size of the devices excessively occupies the already limited space of the transformer platform, restricting the arrangement of transformer bushings and live-line operations; third, more components mean higher manufacturing costs. Currently, the market price for a standard surge arrester (corresponding to a nominal discharge current of 5kA) from a reputable manufacturer is typically between 100 and 200 yuan. Adding complex components significantly increases the cost, sometimes even resulting in component prices exceeding the price of the arrester itself – a "putting the cart before the horse" situation. Considering the operational scale of my country's power distribution network, these structures are acceptable for localized "point" applications, but large-scale "area" applications are unacceptable. Therefore, in the power industry standard DL / T... In the GB / T 1292-2013 "Guidelines for Lightning Protection of Overhead Insulated Lines in Distribution Networks" and its latest revision, the aforementioned complex structure surge arresters are not recommended. Furthermore, under current installation methods, the high-voltage end of the gapless surge arrester is connected to the high-voltage side bushing guide rod of the distribution transformer via a connecting line and a T-junction down conductor. The low-voltage end is connected via a grounding down conductor down the support pole to the support crossarm of the distribution transformer, and then horizontally led to the transformer casing for electrical connection, achieving parallel installation between the surge arrester and the high-voltage side bushing of the distribution transformer. According to standard design documents, the equivalent connecting line length between the gapless surge arrester and the high-voltage side bushing is approximately 3.8m. Under lightning overvoltage, the bushing withstands the voltage of the surge arrester, which is the sum of the residual voltage of the surge arrester and the impulse voltage drop of all connecting lines. Therefore, the surge arrester's protection of the distribution transformer is insufficient, which is the main reason for the frequent occurrence of lightning strike faults in distribution transformers. Summary of the Invention

[0006] The purpose of this invention is to provide a gapless surge arrester for 10kV lines using pole-mounted transformers, so as to solve the problem that surge arresters cannot be installed and removed while the line is powered on.

[0007] The present invention features a protruding structure on the surge arrester body that corresponds to the shape of the surge arrester mounting hole on the mounting bracket, enabling connection with a simple structure. The gapless surge arrester for 10kV lines on pole-mounted transformer platforms provided by the present invention includes a mounting bracket. The mounting bracket is designed to be installed on the outside of the heat sink of the distribution transformer and connected to the base angle steel of the pole-mounted transformer platform, which greatly reduces the space occupied by the transformer platform. The gapless surge arrester for 10kV lines on pole-mounted transformers provided by this invention uses magnetic plug terminals and magnetic socket segments for connection. With the help of auxiliary tools, compared with the complex design of existing fuses and other technologies, the surge arrester can be disassembled and installed without interrupting power to the line with a simple design. It is low in cost and can be used on a large scale. This invention includes an additional grounding wire structure design. The grounding wire adopts the most economical technical route of reducing the equivalent connection length between the surge arrester and the bushing to improve the protection effect of the surge arrester. Under the premise of maintaining the existing structure and wiring of the transformer station, the surge resistance performance of the distribution transformer can be significantly improved, thereby greatly extending the safe operating life of the surge arrester.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a gapless surge arrester for a 10kV line on a pole-mounted transformer platform, comprising a mounting bracket, a surge arrester body, connecting wires, magnetic plug terminals, and magnetic socket terminals. The mounting bracket includes a vertical frame and a horizontal frame. The horizontal frame is provided with multiple surge arrester mounting holes and opening slots. Each surge arrester mounting hole corresponds to an opening slot, and the corresponding surge arrester mounting hole and opening slot are connected. The two ends of the connecting line are respectively connected to the first end of the surge arrester body and the first end of the magnetic plug terminal; The surge arrester body has an outward-facing, non-penetrating first screw hole at the axial position of the first end. The first screw hole is fastened to the first end of the connecting wire and is covered and sealed by an insulating jacket. The second end of the surge arrester body is provided with a protruding structure. A non-penetrating second screw hole is provided at the axial position of the protruding structure. The second screw hole is connected to the mounting screw. The surge arrester mounting hole matches the shape of the protruding structure and is used to sink into the protruding structure. The mounting screw matches the shape of the opening groove and is provided with a nut for fixing the protruding structure. The second end of the magnetic plug terminal is embedded with a first columnar permanent magnet, and the first end of the magnetic plug terminal is provided with a columnar hole, in which a second columnar permanent magnet is embedded on the bottom surface. The first permanent magnet and the second permanent magnet have opposite polarities. The second end of the magnetic plug terminal is inserted and connected to the first end of the magnetic plug terminal.

[0009] The mounting bracket is installed on the column-mounted transformer platform. The column-mounted transformer platform includes a base angle steel, a high-voltage side bushing, and an outer cover plate. The base angle steel is provided with an opening, and the high-voltage side bushing is provided with a threaded guide rod. The mounting bracket is installed on the outside of the heat sink of the distribution transformer, the upright is fixedly connected to the opening on the distribution transformer, and the second end of the magnetic plug terminal is connected to the threaded guide rod on the high-voltage side bushing.

[0010] The surge arrester has a ring pull ring on the outer wall of the magnetic plug terminal body.

[0011] The second end of the magnetic plug terminal is made into a flat body and has a terminal mounting hole. The terminal mounting hole matches the threaded guide rod of the power distribution transformer, and the terminal mounting hole can be fitted into the threaded guide rod for fastening with a nut.

[0012] The surge arrester body includes a resistor element unit, an insulating jacket with shed skirts, a high-voltage end flange, and a low-voltage end flange; The resistor element unit is formed by stacking multiple resistor elements. Both ends of the resistor element unit are fixedly connected to the high-voltage end flange and the low-voltage end flange, respectively, and are covered by an insulating jacket. The first screw hole is located at the axial position of the high-voltage flange of the surge arrester body. The first screw hole is fastened to the first end of the connecting wire and is covered and sealed by the insulating jacket. The protruding structure is provided on the low-pressure end flange of the surge arrester body, and a second screw hole is provided at the axial position of the protruding structure, and the second screw hole is connected to the mounting screw.

[0013] The present invention provides a gapless surge arrester for a 10kV line on a pole-mounted transformer, which also includes a grounding wire assembly. The grounding wire assembly includes a grounding wire, a first wire lug, a second wire lug, and a slotted clamp. The two ends of the grounding wire are respectively crimped to the first wire lug and the second wire lug. The first wire lug is connected and fastened to the upper cover plate of the distribution transformer via the slotted clamp. A grounding wire mounting hole is provided on the crossbeam of the mounting bracket, and the second wire lug is fastened to the grounding wire mounting hole.

[0014] The present invention provides a gapless surge arrester for a 10kV line on a pole-mounted transformer platform, and also includes auxiliary tools for installing and disassembling the surge arrester body. The auxiliary tools include an insulating rod, a pull bar, calipers, and a sleeve. The first end of the insulating rod is provided with a pull bar, calipers, and a sleeve. The size of the calipers matches the magnetic plug terminal and can fix the magnetic plug terminal. The sleeve can be fitted onto the mounting screw of the low-voltage end of the surge arrester body and lock the nut of the mounting screw.

[0015] Preferably, the present invention provides a spring sheet on the inner wall of the post hole at the first end of the magnetic plug terminal of the surge arrester to deform and squeeze the magnetic plug terminal, so that the magnetic plug terminal can be tightly connected with the magnetic plug terminal.

[0016] This invention provides a method for using auxiliary tools for the gapless surge arrester used on a 10kV line of a pole-mounted transformer, including steps for disassembling the surge arrester and replacing it with a new one: During grid-connected operation, when the surge arrester body is damaged and needs to be replaced, or when sampling inspection requires removing the surge arrester body for testing, the power grid does not need to be shut down using this auxiliary tool. The disassembly process is as follows: S10: When the worker is outside the electrical safety distance, he manipulates the insulating rod, inserts the pull bar at the end into the pull ring of the magnetic plug terminal, pulls the insulating rod, pulls the magnetic plug terminal out of the magnetic socket terminal, so that the high voltage end of the surge arrester body is de-energized, and adjusts the connection wire to hang down naturally. S20: Manipulate the insulating rod, put the sleeve on the mounting screw of the surge arrester body and lock the fixing nut on the mounting screw, rotate the insulating rod to loosen the nut a certain distance but without disengaging it from the mounting screw, lift the insulating rod to raise the surge arrester body, so that the protruding structure of the low-voltage flange is disengaged from the surge arrester mounting hole, move the insulating rod along the direction of the opening slot to move the surge arrester body out of the mounting bracket, and lower the insulating rod to remove the surge arrester body; When using this auxiliary tool to replace the main body of the surge arrester, the power grid remains energized. The installation process is as follows: S100: When the worker is outside the electrical safety distance, the worker should attach the nut and anti-loosening device to the mounting screw of the surge arrester body, insert it into the sleeve of the auxiliary tool, and let the nut lock in the sleeve. The mounting screw should be partially exposed. The worker should raise the insulating rod to lift the surge arrester body, and send the exposed part of the mounting screw into the opening slot of the mounting bracket. The worker should then move the insulating rod horizontally to move the surge arrester to the mounting hole position. Then, the worker should rotate the insulating rod to adjust the protruding structure of the low-voltage flange until it sinks into the surge arrester mounting hole. After the surge arrester mounting hole locks the protruding structure of the low-voltage flange, the worker should continue to rotate the insulating rod to tighten the nut.

[0017] S200: Continue manipulating the insulating rod, insert the pull bar into the pull ring of the naturally hanging magnetic plug terminal, raise the insulating rod to drive the connecting line upward until it is straight, at this time the magnetic plug terminal is facing upward, with the assistance of the pulling force of the connecting line, the insulating rod can be adjusted to make the magnetic plug terminal snap into the clamp, at this time the magnetic plug terminal is fixed by the pull bar and the clamp, adjust the insulating rod to align the magnetic plug terminal with the magnetic socket terminal, push the insulating rod forcefully, the magnetic plug terminal is inserted into the magnetic socket terminal, the high voltage end of the surge arrester body is energized, adjust the insulating rod to disengage from the magnetic plug terminal, and retract the auxiliary tool.

[0018] The optimized installation method for the 10kV gapless metal oxide surge arrester on the pole-mounted transformer platform involves the following steps: S1: When installing the surge arrester for the first time, the line is de-energized, the vertical and horizontal frames of the mounting bracket are assembled into one piece, and the vertical frame is securely connected to the base angle steel of the distribution transformer. S2: Insert the threaded guide rod of the high-voltage side bushing of the distribution transformer into the terminal mounting hole of the magnetic plug terminal, adjust the first end of the magnetic plug terminal to face the mounting bracket and tighten it with a nut; S3: The first end of the connecting wire is fixedly connected to the high-voltage flange of the surge arrester body, and the second end of the connecting wire is fastened to the magnetic plug terminal. S4: Insert the mounting screw of the low-voltage end of the surge arrester body into the surge arrester mounting hole of the mounting bracket, and adjust the position so that the protruding structure of the low-voltage end flange sinks into the surge arrester mounting hole. Put the nut and anti-loosening parts into the mounting screw and tighten them. S5: Securely connect the second lug of the grounding wire to the grounding mounting hole of the mounting bracket, and connect and press the first lug to the upper cover plate of the distribution transformer via the slotted wire clamp. S6: Insert the magnetic plug terminal into the magnetic socket terminal.

[0019] The beneficial effects of this invention are as follows: 1. This invention provides a novel 10kV gapless surge arrester for pole-mounted transformer substations that can be energized and replaced. The product has a simple structure, fewer components, is easy to assemble and install on site, is small in size, does not occupy much space in the transformer substation, has low cost, and is suitable for large-scale application. Furthermore, all high-voltage energized components are fully insulated from the outside, eliminating the risk of short circuits caused by foreign objects due to exposed energized nodes. The overall technical and economic efficiency is significantly better than existing products.

[0020] 2. The gapless surge arrester provided by this invention has the function of replacing the surge arrester body under energized conditions. By cleverly utilizing the slotted mounting holes and magnetically attracted terminals, it is easy to connect and disconnect. The old surge arrester body can be quickly disassembled and the new surge arrester body can be installed remotely by operating the insulated rod-type matching tool without interrupting the power supply to the line. This solves the pain point of having to shut down the line when the surge arrester body fails or is sampled for inspection, and reduces operation and maintenance costs.

[0021] 3. This invention also provides an optimized installation scheme for gapless surge arresters used in 10kV lines on pole-mounted transformer substations. This installation scheme adopts the most economical technical route of reducing the equivalent connection length between the surge arrester and the bushing to improve the protection effect of the surge arrester. While maintaining the existing structure and wiring of the transformer substation, it can significantly improve the lightning withstand performance of the distribution transformer. Through electromagnetic transient process modeling and simulation calculations, it is found that under the current installation scheme for gapless surge arresters on pole-mounted transformer substations, the equivalent electrical connection length between the surge arrester and the high-voltage side bushing of the distribution transformer is approximately 3.8m, and the safe operating life of the distribution transformer under 10kV side lightning intrusion overvoltage is only 65 years. Under the installation scheme provided by this invention, the equivalent connection length between the surge arrester and the high-voltage side bushing of the distribution transformer is reduced to less than 0.8m, and the safe operating life of the distribution transformer under 10kV side lightning intrusion overvoltage is significantly increased to no less than 460 years. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the external structure and installation scheme of a new type of gapless surge arrester for pole-mounted transformers; Figure 2 This is a schematic diagram of the mounting bracket structure; Figure 3 This is a schematic diagram of the lightning arrester's main structure; Figure 4 A schematic diagram of the magnetic plug terminals and magnetic socket terminals; Figure 5 This is a schematic diagram of the grounding wire structure; Figure 6 This is a schematic diagram of the supporting tools used for live disassembly and installation of the surge arrester body.

[0023] Wherein: 1-mounting bracket; 2-surge arrester body; 3-connecting wire; 4-magnetic plug terminal; 5-magnetic socket terminal; 6-Grounding wire assembly; 7-Auxiliary tools; 81-Base angle steel; 811-Opening; 821-Threaded guide rod; 82-High voltage side bushing; 83-Outer casing cover; 11-Upright frame; 12-Horizontal frame; 13-Mounting hole; 14-Opening slot; 15-Ground wire mounting hole; 21-Resistor element; 22-Insulating jacket with umbels; 231-High voltage end flange; 232-Low voltage end flange; 24-Mounting bolt; 41-First columnar permanent magnet; 42-Pull ring; 51-Terminal mounting hole; 52-Spring; 53-Second columnar permanent magnet; 54-Post hole; 61-Grounding wire; 621-First wire lug; 622-Second wire lug; 63-Slotted wire clamp; 71-Insulating rod; 72-Pull bar; 73-Caliber; 74-Sleeve. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0025] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] This invention provides a gapless surge arrester for a 10kV line on a pole-mounted transformer platform. The gapless surge arrester for a 10kV line on a pole-mounted transformer platform has a simple structure and low cost, making it easy to install and disassemble, and suitable for large-scale application. The gapless surge arrester for a 10kV line on a pole-mounted transformer platform includes a mounting bracket 1, a surge arrester body 2, a connecting wire 3, a magnetic plug terminal 4, and a magnetic insertion hole terminal 5. The mounting bracket 1 includes a vertical frame 11 and a horizontal frame 12. The horizontal frame 12 has multiple surge arrester mounting holes 13, which are connected to opening slots 14. The two ends of the connecting wire 3 are respectively connected to the first end of the surge arrester body 2 and the first end of the magnetic plug terminal 4. A key feature of this invention is that the first end of the surge arrester body 2 has an outward-facing, non-penetrating first screw hole at its axial position. The first screw hole is fastened to the first end of the connecting wire 3 and sealed by the insulating jacket 22; the second end is provided with a protruding structure, and a non-penetrating second screw hole is provided at the axial position of the protruding structure. The second screw hole is connected to the mounting screw 24. The lightning arrester mounting hole 13 matches the shape of the protruding structure and is used to sink into the protruding structure. The mounting screw 24 matches the shape of the opening groove 14. The mounting screw 24 is provided with a nut for fixing the protruding structure; the second end of the magnetic plug terminal 4 is embedded with a first columnar permanent magnet 41. The first end of the magnetic plug terminal 5 is provided with a columnar hole 54. The bottom surface of the columnar hole is embedded with a second columnar permanent magnet 53. The first permanent magnet 41 and the second permanent magnet 53 have opposite polarities. The second end of the magnetic plug terminal 4 is inserted and connected to the first end of the magnetic plug terminal 5.

[0028] With the above settings, the shape of the surge arrester mounting hole 13 matches the shape of the protruding structure, and the shape of the mounting screw 24 matches the shape of the opening slot 14. The simple structure realizes the connection between the surge arrester body 2 and the mounting bracket 1. The second end of the magnetic plug terminal 4 is inserted and connected to the first end of the magnetic socket terminal 5, which facilitates the installation and removal of the surge arrester body 2.

[0029] The following is with reference to the appendix. Figures 1 to 6 The present invention will be described in detail below.

[0030] like Figure 1 As shown, the mounting bracket 1 is installed on the column-mounted transformer platform. The column-mounted transformer platform includes a base angle steel 81, a high-voltage side bushing 82, and an outer cover plate 83. The base angle steel 81 is provided with an opening 811, and the high-voltage side bushing 82 is provided with a threaded guide rod 821. Mounting bracket 1 is installed on the outside of the heat sink of the distribution transformer. The upright 11 is fixedly connected to the opening 811 on the distribution transformer. The second end of the magnetic plug terminal 5 is connected to the threaded guide rod 821 on the high-voltage side bushing 82.

[0031] The preferred material for the mounting bracket 1 is steel plate. To ensure mechanical strength, channel steel, T-shaped steel, or steel with reinforcing ribs can be used, and the surface should be galvanized for corrosion protection. Provided the space is sufficiently compact, the typical structure can be designed in any shape, such as "П" or "I". Taking the "П" shaped structure as an example, the mounting bracket 1 surrounds the heat sink of the distribution transformer, and the upright frame 11 of the mounting bracket 1 is connected and fixed using the openings on the base angle steel 81 of the distribution transformer.

[0032] By setting up the above, the mounting bracket 1 is placed on the outside of the column-mounted transformer platform, so as to achieve the purpose of not occupying the transformer platform space.

[0033] like Figure 2 As shown, the mounting bracket 1 includes a vertical frame 11 and a horizontal frame 12. Preferably, three irregularly square surge arrester mounting holes 13 are evenly distributed along a straight line on the horizontal frame, with an adjacent interval of not less than 200mm. Each surge arrester mounting hole 13 is connected to a serpentine opening slot 14, which extends to the edge of the horizontal frame.

[0034] The lightning arrester mounting hole 13 is preferably located outside the outer edge of the heat sink of the distribution transformer, so as to facilitate the operation of the personnel on the ground using auxiliary tools 7 from the remote end to realize the disassembly and installation of the lightning arrester body 2.

[0035] A grounding hole 15 is provided around the surge arrester mounting hole 13 near the middle position. The diameter of the hole is between Φ12 and Φ16 mm.

[0036] like Figure 3 As shown, the surge arrester body 2 includes a resistor element unit, an insulating jacket 22 with a shed, a high-voltage flange 231 and a low-voltage flange 232; the first end of the surge arrester body 2 contains the high-voltage flange 231, and the second end contains the low-voltage flange 232.

[0037] The resistor element unit is formed by stacking multiple resistor elements 21. The two ends of the resistor element unit are fixedly connected to the high-voltage flange 231 and the low-voltage flange 232, respectively, and the outer surface is covered with an insulating jacket 22.

[0038] The rated voltage of the surge arrester body 2 is 17kV, and the nominal discharge current is divided into two types: 5kA and 10kA. It can adopt a wound type structure, a cylindrical structure or a cage type structure. With the help of components and materials, multiple resistors 21 and flanges 231 and 232 at both ends are stacked and sealed into a rigid core. The outer surface insulating jacket 22 is preferably a one-time injection molded silicone rubber composite jacket. The technical parameters should comply with the provisions of GB / T 11032-2020 "AC gapless metal oxide surge arresters".

[0039] The first bolt hole of the high-pressure end flange 231 is used to fasten the connecting wire 3, and the connecting wire root section is wrapped and covered with insulating material, preferably silicone rubber composite material.

[0040] The second bolt hole of the low-pressure end flange 232 should be fitted with a mounting bolt 24 of nominal diameter M10~M16 for fixing the surge arrester body 2. The mounting bolt 24 matches the opening slot 14, and its nominal diameter is 0.5mm~1mm smaller than the width of the opening slot 14, so that the mounting bolt 24 can pass through the opening slot 14 and move to the position of the surge arrester mounting hole 13. The exposed part of the low-pressure end flange 232 is designed as a raised structure so that the boss can be recessed into the surge arrester mounting hole 13 when installing the surge arrester body 2. It is preferable to adopt a columnar boss structure, which is consistent with the shape of the surge arrester mounting hole 13 but slightly smaller in size.

[0041] The connecting wire 3 is preferably made of soft copper wire with a silicone rubber insulation layer with a thickness of 1mm to 3mm, a cross-sectional area of ​​12mm2 to 20mm2, and a length not exceeding 400mm. The first end of the connecting wire 3 is electrically connected to and secured to the high-voltage flange 231 of the surge arrester body 2, and the second end is electrically connected to and secured to the first end of the magnetic plug terminal 4.

[0042] like Figure 4 As shown, the magnetic plug terminal 4 and the magnetic socket terminal 5 are preferably made of copper. The magnetic plug terminal 4, the first columnar permanent magnet 41, the magnetic socket terminal 5, the second columnar permanent magnet 53, and the column hole 54 are preferably made of matching cylinders to facilitate insertion. The first columnar permanent magnet 41 and the second columnar permanent magnet 53 are preferably made of neodymium iron boron material, but other magnetic materials that can achieve the purpose can also be used as substitutes.

[0043] The main body of the magnetic plug terminal 4 has an annular pull ring 42 on its side wall, which is generally circular.

[0044] The second end of the magnetic plug terminal 5 is made into a flat body and has a terminal mounting hole 51. The terminal mounting hole 51 matches the threaded guide rod 821 of the distribution transformer. The terminal mounting hole 51 can be fitted into the threaded guide rod 821 and fastened with a nut.

[0045] The surfaces of the magnetic plug terminal 4 and the magnetic socket terminal 5 that are exposed for extended periods are covered with a silicone rubber insulating layer with a thickness of 1mm to 3mm.

[0046] The inner wall of the post hole 54 at the first end of the magnetic plug terminal 5 is provided with a spring piece 52 to deform and squeeze the magnetic plug terminal, so that the magnetic plug terminal 4 and the magnetic plug terminal 5 are tightly connected. Preferably, 3 to 4 long strip-shaped or petal-shaped copper spring pieces are provided.

[0047] With the above settings, when the magnetic plug terminal 4 is inserted into the magnetic socket terminal 5, the copper spring deforms and squeezes the magnetic plug terminal 4, so that the magnetic plug terminal 4 and the magnetic socket terminal 5 can be tightly connected through a sufficiently large copper contact surface to meet the current carrying requirements of the surge arrester.

[0048] This invention provides a novel 10kV gapless surge arrester for pole-mounted transformer substations that can be energized and replaced. The product has a simple structure, fewer components, is easy to assemble and install on site, is small in size, does not occupy much space in the transformer substation, has low cost, and is suitable for large-scale application. Furthermore, all high-voltage energized components are fully insulated from the outside, eliminating the risk of short circuits caused by foreign objects due to exposed energized nodes. The overall technical and economic efficiency is significantly better than existing products.

[0049] like Figure 5 As shown, the present invention also provides an installation scheme for a gapless surge arrester for a 10kV line on a pole-mounted transformer, which can significantly improve the lightning protection performance of the surge arrester. In addition to the components of Embodiment 1, it also includes a grounding wire assembly 6. The grounding wire assembly 6 includes a grounding wire 61, a first wire lug 621, a second wire lug 622, and a slotted clamp 63. The first wire lug 621 and the second wire lug 622 are respectively crimped to both ends of the grounding wire 61. The first wire lug 621 is connected and fastened to the upper cover plate 83 of the distribution transformer via the slotted clamp 63. A grounding wire mounting hole 15 is provided on the crossbeam 12 of the mounting bracket 1, and the second wire lug 622 is fastened to the grounding wire mounting hole 15.

[0050] The grounding wire 61 is preferably a braided soft copper wire with a cross-sectional area of ​​25mm² to 50mm² and a length not exceeding 400mm.

[0051] The first wire lug 621 is electrically connected to the upper cover plate 83 of the distribution transformer via the slotted wire clamp 63 and is pressed and tightened. The wire lug 622 is connected to the ground wire mounting hole 15 of the mounting bracket 1 via bolts and nuts.

[0052] Under the general dimensions of domestic distribution transformers, the mounting bracket 1 is fixed on the base angle steel 81 of the distribution transformer, and the mounting bracket 1 is short-circuited to the outer cover plate 83 of the distribution transformer by the grounding wire assembly 61. Under this installation scheme, the effective connection length between the surge arrester and the high-voltage bushing can be controlled within 0.8m.

[0053] The optimized installation method for the 10kV gapless metal oxide surge arrester on the pole-mounted transformer can significantly improve the surge arrester's lightning protection performance. The installation steps are as follows: S1: When installing the surge arrester for the first time, the line is de-energized. The upright frame 11 and the cross frame 12 of the mounting bracket 1 are assembled into one piece. The upright frame 11 is fastened to the base angle steel 81 of the distribution transformer. S2: Insert the threaded guide rod 821 of the high-voltage side bushing 82 of the distribution transformer into the terminal mounting hole 51 of the magnetic plug terminal 5, adjust the first end of the magnetic plug terminal 5 to face the mounting bracket 1 and tighten it with a nut. S3: The first end of the connecting wire 3 is fixedly connected to the high-voltage flange 231 of the surge arrester body 2, and the second end of the connecting wire 3 is fastened to the magnetic plug terminal 4. S4: Insert the mounting screw 24 of the low-voltage end of the surge arrester body 2 into the surge arrester mounting hole 13 of the mounting bracket 1, and adjust the position so that the protruding structure of the low-voltage end flange 232 sinks into the surge arrester mounting hole 13. Put the nut and anti-loosening parts into the mounting screw 24 and tighten them. S5: Securely connect the second lug 622 of the grounding wire 61 to the grounding mounting hole 15 of the mounting bracket 1, and connect and press the first lug 621 to the outer cover plate 83 of the distribution transformer via the slotted wire clamp 63. S6: Insert the magnetic plug terminal 4 into the magnetic socket terminal 5.

[0054] Through the aforementioned structure and optimized installation scheme, this scheme improves the protection effect of the surge arrester by reducing the equivalent connection length between the surge arrester and the bushing, which is the most economical technical approach. While maintaining the existing structure and wiring of the transformer substation, it significantly improves the lightning withstand performance of the distribution transformer. Through electromagnetic transient process modeling and simulation calculations, it was found that under the current installation scheme for gapless surge arresters used in pole-mounted transformer substations, the equivalent electrical connection length between the surge arrester and the high-voltage side bushing of the distribution transformer is approximately 3.8m, and the safe operating life of the distribution transformer under 10kV side lightning intrusion overvoltage is only 65 years. Under the installation scheme provided by this invention, the equivalent connection length between the surge arrester and the high-voltage side bushing of the distribution transformer is reduced to less than 0.8m, and the safe operating life of the distribution transformer under 10kV side lightning intrusion overvoltage is significantly increased to no less than 460 years.

[0055] like Figure 6 As shown, the auxiliary tools for installing gapless surge arresters for 10kV lines on pole-mounted transformer platforms include an insulating rod 71, a pull rod 72, a clamp 73, and a sleeve 74. The first end of the insulating rod 71 is provided with a pull rod 72, a clamp 73, and a sleeve 74.

[0056] The insulating rod 71 is preferably an epoxy resin insulating rod 71 with a length of 2m to 3m.

[0057] The pull rod 72 and sleeve 74 provided at the first end of the insulating rod 71 are preferably made of copper or steel, and the caliper 73 is preferably made of steel.

[0058] The first end of the insulating rod 71 is provided with a pull rod 72, a clamp 73, and a sleeve 74. The preferred structure is as follows: with the insulating rod 71 as the axis, the pull rod 72 and the clamp 73 are offset at an angle of less than or equal to 45°. The diameter of the pull rod 72 is about 10~15mm smaller than the inner diameter of the pull ring 42 of the magnetic plug terminal 4. The size of the clamp 73 matches the magnetic plug terminal 4 and can fix the magnetic plug terminal 4. The sleeve 74 can be inserted into the mounting screw 24 of the low-voltage end of the surge arrester body 2 and lock the nut of the mounting screw 24.

[0059] The auxiliary tool 7 for the 10kV line gapless surge arrester of the above-mentioned pole-mounted transformer has the function of replacing the surge arrester body under energized conditions. By cleverly utilizing the slotted mounting holes and magnetic terminals, it is easy to connect and disconnect. The old surge arrester body can be quickly removed and the new surge arrester body can be installed by remotely operating the insulated rod-type matching tool without interrupting the power supply to the line. This solves the problem of the pain point that the line must be de-energized when the surge arrester body fails or is sampled for inspection, and reduces the operation and maintenance costs.

[0060] During grid-connected operation, when the surge arrester body is damaged and needs to be replaced, or when sampling inspection requires removing the surge arrester body for testing, disassembly is performed using auxiliary tools without power outage. The disassembly steps are as follows: S10: When the worker is outside the electrical safety distance, he uses the auxiliary tool 7 to manipulate the insulating rod 71, inserts the pull bar 72 at the end into the pull ring 42 of the magnetic plug terminal 4, pulls the insulating rod 71 with force, pulls the magnetic plug terminal 4 out of the magnetic plug terminal 5, disconnects the high voltage end of the surge arrester body 2, and adjusts the connecting wire 3 to hang down naturally. S20: Manipulate the insulating rod 71, put the sleeve 74 on the mounting screw 24 of the surge arrester body 2 and lock its fixing nut, rotate the insulating rod 71 to loosen the nut a certain distance but without disengaging it from the mounting screw 24, lift the insulating rod 71 slightly to raise the surge arrester body 2, so that the protruding structure of the low-voltage flange 232 disengages from the surge arrester mounting hole 13, move the insulating rod 71 along the direction of the opening slot 14 to move the surge arrester body 2 out of the mounting bracket 1, and lower the insulating rod 71 to remove the surge arrester body 2.

[0061] When replacing the main body of the surge arrester using auxiliary tools, the power grid can remain energized. The installation process is as follows: S100: When the worker is outside the electrical safety distance, the worker attaches a nut and anti-loosening device to the mounting screw 24 of the surge arrester body 2, inserts it into the sleeve 74 of the auxiliary tool 7, and the nut is locked in the sleeve 74. The mounting screw 24 is partially exposed. The worker raises the surge arrester body 2 with the rising insulating rod 71, sends the exposed section of the mounting screw 24 into the opening slot 14 of the mounting bracket 1, and moves the insulating rod 71 horizontally to send the surge arrester to the position of the surge arrester mounting hole 13. Then, the worker rotates the insulating rod 71 to adjust the protruding structure of the low-voltage flange 232 until it sinks into the surge arrester mounting hole 13, so that the surge arrester mounting hole 13 locks the protruding structure of the low-voltage flange 232. Then, the worker continuously rotates the insulating rod 71 to tighten the nut.

[0062] S200: Continue manipulating the insulating rod 71, insert the pull rod 72 into the pull ring 42 of the naturally hanging magnetic plug terminal 4, raise the insulating rod 71 to drive the connecting line 3 upward until it is straight. At this time, the magnetic plug terminal 4 is facing upward. With the assistance of the pulling force of the connecting line 3, the insulating rod 71 can be adjusted to make the magnetic plug terminal 4 snap into the clamp 73. At this time, the magnetic plug terminal 4 is fixed by the pull rod 72 and the clamp 73. Adjust the insulating rod 71 to align the magnetic plug terminal 4 with the magnetic socket terminal 5, push the insulating rod 71 forcefully, and the magnetic plug terminal 4 is inserted into the magnetic socket terminal 5. The high voltage end of the surge arrester body is energized. Adjust the insulating rod 71 to disengage from the magnetic plug terminal 4 and retract the auxiliary tool 7.

[0063] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

Claims

1. A gapless surge arrester for a 10kV line using a pole-mounted transformer, characterized in that, Includes mounting bracket (1), surge arrester body (2), connecting wire (3), magnetic plug terminal (4) and magnetic socket terminal (5); The mounting bracket (1) includes a vertical frame (11) and a horizontal frame (12). The horizontal frame (12) is provided with multiple surge arrester mounting holes (13) and opening slots (14). Each surge arrester mounting hole (13) corresponds to an opening slot (14), and the corresponding surge arrester mounting hole (13) and opening slot (14) are connected. The two ends of the connecting line (3) are respectively connected to the first end of the surge arrester body (2) and the first end of the magnetic plug terminal (4); The surge arrester body (2) has an outward-facing, non-penetrating first screw hole at the first end of the shaft. The first screw hole is fastened to the first end of the connecting wire (3) and is covered and sealed by the insulating jacket (22). The second end of the surge arrester body (2) is provided with a protruding structure. The protruding structure has an outward-facing, non-penetrating second screw hole at the axial position. The second screw hole is connected to the mounting screw (24). The surge arrester mounting hole (13) matches the shape of the protruding structure and is used to sink into the protruding structure. The mounting screw (24) matches the shape of the opening groove (14). The mounting screw (24) is provided with a nut for fixing the protruding structure after installation. The second end of the magnetic plug terminal (4) is embedded with a first columnar permanent magnet (41), and the first end of the magnetic plug terminal (5) is provided with a columnar hole (54), and the bottom surface of the columnar hole is embedded with a second columnar permanent magnet (53). The first permanent magnet (41) and the second permanent magnet (53) have opposite polarities. The second end of the magnetic plug terminal (4) is connected to the first end of the magnetic plug terminal (5).

2. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 1, characterized in that, The mounting bracket (1) is installed on the column-mounted transformer platform. The column-mounted transformer platform includes a base angle steel (81), a high-voltage side bushing (82), and an outer shell cover plate (83). The base angle steel (81) is provided with an opening (811), and the high-voltage side bushing (82) is provided with a threaded guide rod (821). The mounting bracket (1) is installed on the outside of the heat sink of the power distribution transformer. The stand (11) is fixedly connected to the opening (811) on the power distribution transformer. The second end of the magnetic plug terminal (5) is connected to the threaded guide rod (821) on the high-voltage side bushing (82).

3. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 2, characterized in that, The magnetic plug terminal (4) of the surge arrester has an annular pull ring (42) on the outer side wall of the main body.

4. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 3, characterized in that, The second end of the magnetic plug terminal (5) is flat, and the flat body is provided with a terminal mounting hole (51). The terminal mounting hole (51) matches the threaded guide rod (821) of the power distribution transformer. The terminal mounting hole (51) can be fitted into the threaded guide rod (821) and fastened with a nut.

5. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 4, characterized in that, The surge arrester body (2) includes a resistor element unit, an insulating jacket with a shed (22), a high-voltage end flange (231), and a low-voltage end flange (232). The resistor unit is formed by stacking multiple resistors (21). The two ends of the resistor unit are fixedly connected to the high-voltage flange (231) and the low-voltage flange (232) respectively, and are covered by an insulating jacket (22). The first screw hole is located at the axial position of the high-voltage end flange (231) of the surge arrester body (2). The first screw hole is fastened to the first end of the connecting wire (3) and is covered and sealed by the insulating jacket (22). The protruding structure is provided on the low-pressure end flange (232) of the surge arrester body (2), and a second screw hole is provided at the axial position of the protruding structure, and the second screw hole is connected to the mounting screw (24).

6. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 5, characterized in that, It also includes a grounding wire assembly (6), which includes a grounding wire (61), a first wire lug (621), a second wire lug (622) and a slotted wire clamp (63). The grounding wire (61) is crimped to the first wire lug (621) and the second wire lug (622) at both ends. The first wire lug (621) is connected and fastened to the upper cover plate (83) of the distribution transformer via the slotted wire clamp (63). A grounding wire mounting hole (15) is provided on the crossbeam (12) of the mounting bracket (1), and the second wire lug (622) is fastened to the grounding wire mounting hole (15).

7. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 6, characterized in that, It also includes auxiliary tools (7) for installing and removing the surge arrester body (2); The auxiliary tool (7) includes an insulating rod (71), a pull rod (72), a caliper (73), and a sleeve (74). The first end of the insulating rod (71) is provided with a pull rod (72), a caliper (73), and a sleeve (74). The size of the caliper (73) matches the magnetic plug terminal (4) and can fix the magnetic plug terminal (4). The sleeve (74) can be inserted into the mounting screw (24) of the low-voltage end of the surge arrester body (2) and lock the nut of the mounting screw (24).

8. The gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 7, characterized in that, The inner wall of the post hole (54) at the first end of the magnetic plug terminal (5) of the surge arrester is provided with a spring piece (52) to deform and squeeze the magnetic plug terminal (4), so that the magnetic plug terminal (4) can be tightly connected with the magnetic plug terminal (5).

9. A method of using an auxiliary tool for a gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 7, characterized in that, This includes the steps for disassembling the surge arrester and replacing it with a new one; During grid-connected operation, when the surge arrester body is damaged and needs to be replaced, or when sampling inspection requires removing the surge arrester body for testing, the power grid does not need to be shut down. The disassembly process is as follows: S10: When the worker is outside the electrical safety distance, he manipulates the insulating rod (71), inserts the end pull bar (72) into the pull ring (42) of the magnetic plug terminal (4), pulls the insulating rod (71), pulls the magnetic plug terminal (4) out of the magnetic plug terminal (5), so that the high voltage end of the surge arrester body (2) is de-energized, and adjusts the connecting wire (3) to hang down naturally. S20: Manipulate the insulating rod (71), put the sleeve (74) on the mounting screw (24) of the surge arrester body (2), and lock the fixing nut on the mounting screw (24). Rotate the insulating rod (71) to loosen the nut a certain distance but not disengage it from the mounting screw (24). Lift the insulating rod (71) to raise the surge arrester body (2) so that the protruding structure of the low-voltage flange (232) disengages from the surge arrester mounting hole (13). Move the insulating rod (71) along the direction of the opening slot (14) to move the surge arrester body (2) out of the mounting bracket (1). Lower the insulating rod (71) to remove the surge arrester body (2). When replacing the main body of the surge arrester, the power grid remains energized. The installation process is as follows: S100: When the worker is outside the electrical safety distance, he puts the nut and anti-loosening parts on the mounting screw (24) of the surge arrester body (2), inserts it into the sleeve (74) of the auxiliary tool (7), the nut is locked in the sleeve (74), the mounting screw (24) is exposed, the rising insulating rod (71) lifts the surge arrester body (2), the exposed part of the mounting screw (24) is sent into the opening slot (14) of the mounting bracket (1), and the insulating rod (71) is moved horizontally to send the surge arrester to the mounting hole (13) position. Then, the insulating rod (71) is rotated to adjust the protruding structure of the low-voltage end flange (232) until it sinks into the surge arrester mounting hole (13), so that the surge arrester mounting hole (13) locks the protruding structure of the low-voltage end flange (232), and then the insulating rod (71) is rotated continuously to tighten the nut. S200: Continue to operate the insulating rod (71), insert the pull rod (72) into the pull ring (42) of the naturally hanging magnetic plug terminal (4), raise the insulating rod (71) to drive the connecting line (3) upward until it is straight. At this time, the magnetic plug terminal (4) faces upward. With the help of the pulling force of the connecting line (3), adjust the insulating rod (71) to make the magnetic plug terminal (4) snap into the clamp (73). At this time, the magnetic plug terminal (4) is fixed by the pull rod (72) and the clamp (73). Adjust the insulating rod (71) to align the magnetic plug terminal (4) with the magnetic socket terminal (5). Push the insulating rod (71) hard, and the magnetic plug terminal (4) is inserted into the magnetic socket terminal (5). The high voltage end of the surge arrester body is energized. Adjust the insulating rod (71) to disengage from the magnetic plug terminal (4) and retract the auxiliary tool (7).

10. An optimized installation method for a gapless surge arrester for a 10kV line on a pole-mounted transformer as described in claim 6, characterized in that, The installation steps are as follows: S1: When installing the surge arrester for the first time, the line is de-energized, and the upright (11) and cross frame (12) of the mounting bracket (1) are assembled into one piece. The upright (11) is fastened to the base angle steel (81) of the distribution transformer. S2: Insert the terminal mounting hole (51) of the magnetic plug terminal (5) into the threaded guide rod (821) of the high-voltage side bushing (82) of the distribution transformer, adjust the first end of the magnetic plug terminal (5) to face the mounting bracket (1) and tighten it with a nut; S3: The first end of the connecting wire (3) is fixedly connected to the high-voltage end flange (231) of the surge arrester body (2), and the second end of the connecting wire (3) is fastened to the magnetic plug terminal (4); S4: Insert the mounting screw (24) of the low-voltage end of the surge arrester body (2) into the surge arrester mounting hole (13) of the mounting bracket (1), and adjust the position so that the protruding structure of the low-voltage end flange (232) sinks into the surge arrester mounting hole (13). Put the nut and anti-loosening parts into the mounting screw (24) and tighten them. S5: Securely connect the second lug (622) of the grounding wire (61) to the grounding mounting hole (15) of the mounting bracket (1), and connect and press the first lug (621) to the upper cover plate (83) of the distribution transformer via the slotted wire clamp (63); S6: Insert the magnetic plug terminal (4) into the magnetic socket terminal (5).

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