17.5 kV ring main unit

Abstract

The invention discloses a 17.5 kV ring main unit. The 17.5 kV ring main unit comprises an outdoor box shell and a ring main unit shell which are integrally designed. The upper end of the box body is hinged with an upper door plate, the middle part is provided with a gas box, the lower end is provided with a cable chamber and a cable withstand voltage test chamber, and the top is an instrument chamber. Load switches are arranged on the two sides of the gas tank symmetrically, and a circuit breaker switch is embedded in the middle of the gas tank and connected through a CV busbar. The load switch is provided with an arc extinguishing grid sheet, an insulating umbrella skirt and a specially-designed grounding contact, so that arc extinguishing can be effectively realized, the insulating performance is improved, and the grounding effect is optimized. The design of the transmission assembly accurately controls the motion of the moving contact. The circuit breaker switch comprises a vacuum bubble and other components, and can efficiently extinguish arc. In addition, the lower end of the load switch is provided with test and incoming and outgoing line terminals, the driving unit is provided with a program lock, and the instrument chamber is provided with a power supply and a voltage transformer. The ring main unit optimizes space utilization through integrated design, has remarkable advantages in the aspects of electrical performance, operation convenience and maintenance, is suitable for various electric power scenes, and powerfully ensures stable operation of an electric power system.

Description

Technical Field

[0001] The present invention relates to the field of ring network boxes, and in particular to a 17.5kV ring network box. Background Art

[0002] In the power system, the ring main box is a key device to ensure power distribution and control. With the diversification of power demand and the continuous development of the power grid, ring main boxes of different voltage levels are used in various scenarios. For the 17.5kV voltage level ring main box, it corresponds to the voltage level of the rated voltage sequence 1 in the IEC62271-1 standard, which is usually used in power networks with nominal voltages of 13.8kV and 15kV. The manufacturing cost of the 24kV ring main box itself is relatively high. Its internal electrical components, insulation materials, etc. need to be designed and selected according to the 24kV standard. These high-performance components lead to an increase in overall costs. Due to the large structure and size of the 24kV ring main box, it requires a larger space and stricter transportation conditions during transportation, which also increases transportation costs. The 24kV ring main box is large in size and takes up more valuable space in places such as substations or distribution rooms. For some places with limited space, additional space modifications may be required for installation, which not only increases construction costs, but also may affect the layout and operation efficiency of the entire power system.

[0003] The insulation parameters such as the rated power frequency withstand voltage and lightning impulse withstand voltage of the 12kV ring network box are quite different from those of the 17.5kV ring network box. According to the IEC standard, the rated power frequency withstand voltage of the 17.5kV circuit breaker and ring network box is 38kV, which is lower than the 42kV rated power frequency withstand voltage of the national standard 12kV circuit breaker and ring network box; and in terms of the lightning impulse withstand voltage parameter requirements between phases and ground and the circuit breaker break, the 17.5kV circuit breaker and ring network box is 95kV, which is much higher than the 75kV rated lightning impulse withstand voltage specified in the national standard 12kV circuit breaker and ring network box.

[0004] In order to find a more economical solution, the market considered using a miniaturized 12kV ring network box for transformation to meet the performance requirements of 17.5kV products, but encountered many technical difficulties in this process: 1. Insulation performance issues. Since the 12kV ring network box itself is a miniaturized product, its appearance and space structure are very compact, which makes it very difficult to improve the insulation performance. The distance between phases and between phases and ground in the ring network box is prone to insufficient insulation at a voltage of 17.5kV, which greatly increases the probability of insulation failure during operation. 2. Space utilization and installation issues: Separate ring network cabinets and outdoor boxes need to be manufactured, transported and installed separately, which not only increases the overall volume and weight, but also requires a larger space during the installation process to accommodate two independent boxes and the connection between them. This increases the difficulty and complexity of installation in some places with limited space. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies of the prior art, the present invention aims to provide a 17.5kV ring network box, which solves the problems existing in the prior art, abandons the conventional form of a separate ring network cabinet plus an outdoor box, adopts an integrated design of an outer box and a ring network cabinet, and directly uses the upper door panel and the cable room door panel of the original ring network cabinet as components of the outer box, which can intuitively reduce the size of the outer box and save product installation space. This innovative structural integration effectively reduces the unnecessary space occupation caused by the splicing of independent boxes, making the overall structure more compact. At the same time, the reasonable layout of the functional rooms inside the box, such as the gas box, cable room, cable withstand voltage test room and instrument room, further optimizes the space utilization efficiency.

[0007] The interior of the gas box adopts a symmetrical layout, with load switches on both sides, a circuit breaker switch embedded in the middle, and connected through a CV busbar, so that the charge distribution is relatively balanced and the distortion of the electric field is reduced. The symmetrical structure allows equal amounts of positive and negative charges to be regularly distributed in space, and the electric field components in each direction offset each other to a certain extent, avoiding excessive accumulation of electric field strength in a single direction. At the same time, the compact layout shortens the electrical distance between the components, allowing the electric field to transition relatively smoothly, reducing the unevenness of the electric field, ensuring that the electric field inside the equipment is in a stable and uniform state, and providing a basic guarantee for the reliable operation of the equipment.

[0008] The left connection of the grounding contact is fixed to the insulating shed, which ensures the stability of the grounding path while not destroying the insulating environment constructed by the insulating shed. The two work together to maintain the overall insulation balance. The inverted T-shaped structure on the right and the arc-shaped structure at the bottom, on the one hand, reduce the grounding resistance by increasing the contact area, and reduce the damage to the insulation caused by the abnormal increase in potential due to poor grounding; on the other hand, it optimizes the electric field distribution, so that the electric field lines evenly bypass the grounding contact, avoiding local insulation breakdown caused by electric field concentration, and comprehensively ensuring the insulation safety of the equipment under high voltage operation.

[0009] A cable withstand voltage test room is set above the cable room, and a test terminal and an inlet and outlet terminal are set at the lower end of the load switch. The test terminal is connected to the grounding contact through a copper rod, and the inlet and outlet terminal is connected to the moving contact seat through a copper rod. In this way, the tester does not need to enter the cable compartment, but only needs to open the corresponding components outside to test the cable insulation level conveniently and safely, overcoming the cumbersome and dangerous drawbacks of traditional ring network box testing.

[0010] (II) Technical solution

[0011] To achieve the above object, the present invention provides the following technical solution: a 17.5kV ring network box, comprising a box body, a gas box is provided in the middle of the box body, a cable room and a cable withstand voltage test room are provided at the lower end of the gas box, an instrument room is provided at the top of the box body, a symmetrical layout is adopted inside the gas box, two groups of load switches are provided on both sides of the gas box, a circuit breaker switch is embedded between the load switches, and the circuit breaker switch and the load switch are connected through a CV busbar;

[0012] The load switch includes a mounting frame and a load switch drive unit. A load switch transmission assembly is provided on the left side of the load switch drive unit. A moving contact is hinged at the lower end of the load switch transmission assembly. A moving contact seat is hinged at the bottom of the moving contact. An upper static contact is provided on the upper part of the mounting frame. Arc extinguishing grids are fixed on both sides of the upper static contact. An insulating umbrella skirt and a grounding contact are provided at the front part of the mounting frame.

[0013] Preferably, the left side of the grounding contact is a connecting portion, which is fixed to the insulating shed, and the right side is designed in an inverted T shape, and the bottom of the inverted T shape is an arc shape.

[0014] Preferably, a test terminal and an inlet and outlet terminal are provided at the lower end of the load switch, the test terminal is connected to the grounding contact through a copper rod, and the inlet and outlet terminal is connected to the moving contact seat through a copper rod.

[0015] Preferably, the load switch transmission assembly includes a load switch main shaft transmission-connected to the load switch drive unit, a transmission connector is fixed on the load switch main shaft, an arc-shaped pull plate is hinged at the end of the transmission connector, and a moving contact pull plate is hinged between the arc-shaped pull plates.

[0016] Preferably, an upper crossbeam of a load switch and a lower crossbeam of a load switch are respectively provided on the upper and lower sides of the mounting frame and are made of plastic.

[0017] Preferably, a program lock is provided on the load switch drive unit.

[0018] Preferably, the circuit breaker switch includes a circuit breaker switch drive unit and a fixed component, the upper end of the circuit breaker switch drive unit is transmission-connected with the circuit breaker drive main shaft, a cam connector is arrayed on the drive main shaft, a vacuum bubble pull rod is movably connected to the cam connector, the vacuum bubble pull rod is movably arranged along the longitudinal direction, three groups of vacuum bubbles are arranged inside the fixed component, the lower end of the vacuum bubble pull rod is fixed with the circuit breaker static contact, the lower end of the circuit breaker switch drive unit is provided with a lower isolating transmission component, the lower end of the lower isolating transmission component is hinged with an isolating switch moving contact, the bottom of the isolating switch moving contact is fixed with an isolating switch moving contact seat, the upper part of the isolating switch moving contact seat is connected with a three-phase copper rod, and the ends of the three-phase copper rod are connected with input and output line terminals.

[0019] Preferably, a ground connection row is provided at the bottom of the fixing assembly, and three groups of T-shaped ground contacts are provided at the upper end of the ground connection row.

[0020] Preferably, the lower crossbeam of the load switch is fixedly connected to the fixing assembly.

[0021] Preferably, a flexible connection is provided at the upper end of the vacuum bubble, and two sides of the flexible connection are respectively connected to two groups of load switches.

[0022] Furthermore, a power supply is provided inside the instrument room. The power supply is in the form of an integrated power supply voltage transformer VT. VT directly supplies power to the battery. The battery supplies power to the secondary control circuit and the circuit breaker operation circuit through the power module. No external power supply is required.

[0023] Furthermore, the copper rod connecting the static contact of the load switch to the outlet bushing is relatively long and is fixed by a bracket to prevent the electromotive force generated during operation from causing the copper rod to vibrate and affect the synchronicity of the closing of the load switch.

[0024] Furthermore, the box body includes an outdoor box shell and a ring main unit shell. The outdoor box shell and the ring main unit shell are of an integrated design. An upper door panel is hinged at the upper end of the box body. A special bending design is provided on the shell structure. The upper door panel and the cable room door are further sealed and waterproof by adding sealing strips and the like. At the same time, in order to facilitate checking the switch status and the secondary circuit status, the upper door panel is designed as a flip-up structure.

[0025] (III) Beneficial effects

[0026] The present invention has significant beneficial effects in many aspects. The traditional combination of a separate ring main unit and an outdoor box is abandoned, and an outer box and a ring main unit are integrated into one design. The upper door panel and the cable room door panel of the original ring main unit are used as the outer box, which greatly reduces the overall volume of the equipment. This design effectively saves installation space and is particularly suitable for places with limited space, such as power distribution rooms in old urban communities and power facility renovation projects in narrow streets, which can significantly reduce the difficulty and complexity of installation.

[0027] The interior of the gas box adopts a symmetrical layout, with load switches on both sides and a circuit breaker switch embedded in the middle, and connected through a CV busbar. This layout promotes a highly balanced charge distribution. According to the principle of electric field superposition, the electric field components in each direction can offset each other to a certain extent, effectively avoiding excessive accumulation of electric field strength in a single direction, thereby significantly reducing the distortion of the electric field. Compared with the traditional layout, the compact structural layout of the present invention greatly shortens the electrical distance between the components, allowing the electric field to transition smoothly. For example, the electric field connection between adjacent load switches and circuit breaker switches is more coordinated, and there will be no problems of poor electric field connection and local mutation caused by excessive distance. This makes the electric field inside the equipment always in a stable and uniform ideal state. The stable electric field environment greatly reduces the discharge phenomenon caused by excessive local electric field strength, effectively reduces the probability of equipment failure, ensures the long-term stable operation of the equipment, and strongly supports the reliable power supply of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a 17.5kV ring main box of the present invention with the front cover plate completely removed;

[0029] Figure 2 This is a sectional view of the whole of a 17.5kV ring network box of the present invention;

[0030] Figure 3 It is a cross-sectional view of a gas box in a 17.5kV ring main box of the present invention;

[0031] Figure 4 A schematic diagram of the connection between a load switch and a circuit breaker switch in a 17.5kV ring network box of the present invention;

[0032] Figure 5 It is a schematic diagram of a load switch in a 17.5kV ring network box of the present invention;

[0033] Figure 6 This is an enlarged view of a load switch A in a 17.5kV ring network box of the present invention;

[0034] Figure 7 It is a cross-sectional view of a load switch in a 17.5kV ring network box of the present invention;

[0035] Figure 8It is a schematic diagram of a grounding contact in a 17.5kV ring network box of the present invention;

[0036] Fig. 9 A schematic diagram of a circuit breaker switch in a 17.5kV ring network box of the present invention;

[0037] Fig.10 A schematic diagram of a circuit breaker switch in a 17.5kV ring network box of the present invention with a fixed component removed;

[0038] Fig.11 A 17.5kV ring network box of the present invention Fig.10 The enlarged view of point B in the middle;

[0039] In the figure: 1-box, 2-gas box, 3-cable room, 4-cable withstand voltage test room, 5-instrument room, 6-power supply, 11-outdoor box shell, 12-ring network cabinet shell, 13-upper door plate, 21-load switch, 22-circuit breaker switch, 23-CV busbar, 24-program lock, 211-mounting frame, 212-load switch drive unit, 213-load switch transmission assembly, 214-moving contact, 215-moving contact seat, 216-upper static contact, 217-arc extinguishing grid, 218-insulating umbrella skirt, 219-grounding contact, 2101-test terminal, 2102-inlet and outlet terminals, 2191-connection part, 2111 -Load switch upper beam, 2112-load switch lower beam, 2131-load switch main shaft, 2132-transmission connector, 2133-arc pull plate, 2134-moving contact pull plate, 221-circuit breaker switch drive unit, 2222-fixed assembly, 223-circuit breaker transmission main shaft, 224-cam connector, 225-vacuum bubble pull rod, 226-vacuum bubble, 227-circuit breaker static contact, 228-lower isolation transmission assembly, 229-isolating switch moving contact, 230-isolating switch moving contact seat, 231-three-term copper rod, 233-soft connection, 2221-grounding connection bar, 2222-T-type grounding contact. DETAILED DESCRIPTION

[0040] The following will be combined with the attached examples of the present invention Figure 1-Figure 11 A clear and complete description is given to the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] The present invention provides a technical solution: a 17.5kV ring network box, comprising a box body 1, a gas box 2 is arranged in the middle of the box body 1, a cable room 3 and a cable withstand voltage test room 4 are arranged at the lower end of the gas box 2, an instrument room 5 is arranged on the top of the box body 1, a symmetrical layout is adopted inside the gas box 2, two groups of load switches 21 are arranged on both sides inside the gas box 2, a circuit breaker switch 22 is embedded between the load switches 21, and the circuit breaker switch 22 and the load switch 21 are connected through a CV busbar 23. The box body 1, as the outer shell of the entire ring network box, plays a role in protecting and supporting internal components, protecting the internal equipment from adverse factors such as external physical impact, dust, moisture, etc., ensuring the stable operation of the equipment, and its reasonable structural design also provides a basis for optimizing the internal layout.

[0042] The gas box 2 is located in the middle of the box body, which is the centralized placement area of ​​the core electrical components. It creates a relatively stable operating environment for key equipment such as load switches and circuit breaker switches, prevents the external environment from interfering with electrical performance, and ensures the reliability and safety of power transmission. The cable room 3 is used to introduce and lead out cables to realize the power transmission connection between the ring network box and the external power grid or power-consuming equipment. It is a key channel for power input and output. The internal cable fixing device ensures that the cable connection is stable to avoid looseness and cause failures. The cable withstand voltage test room 4 is specially designed for cable insulation performance testing. With the test terminals and inlet and outlet terminals at the lower end of the load switch, testers can conveniently and safely operate externally to detect whether there are insulation hazards in the cable and ensure the safety of power supply to the power grid. The instrument room 5 carries various monitoring and control instruments and innovative power supply systems, and provides real-time feedback on the operating parameters of the ring network box to provide key data basis for operation and maintenance personnel. The power supply and voltage transformer VT continuously supply energy to the secondary control circuit and the circuit breaker operation circuit to ensure the normal operation of the automation function of the ring network box.

[0043] The box body 1 includes an outdoor box shell 11 and a ring network cabinet shell 12. The outdoor box shell and the ring network cabinet shell are of an integrated design. The upper end of the box body is hinged with an upper door panel 13. By abandoning the conventional form of a separate ring network cabinet plus an outdoor box, the outer box body and the ring network cabinet are designed as an integrated body, and the original upper door panel and cable room door panel of the ring network cabinet are directly used as components of the outer box body. Through the special bending design, not only the overall structure is more compact and stable, but also the strength of the shell is enhanced. After further adding the sealing strip, the sealing and waterproof requirements are effectively met, creating a good operating environment for the internal electrical components. The integrated shell provides a reasonable spatial layout for the various functional areas inside the ring network box. From the gas box to the cable room, the cable withstand voltage test room and the instrument room, each part is closely arranged and independent of each other and organically connected. The special bending design optimizes the use of space while also enhancing the stability of the structure, so that the entire ring network box can adapt to different installation environments and working conditions.

[0044] Two groups of load switches 21 are distributed on both sides of the gas box, and are mainly used for opening and closing control of load current during normal operation, such as access and disconnection of daily power lines, precise regulation of power distribution, and ensuring that different loads are powered on demand. At the same time, they can play a certain isolation role in the early stage of a fault. The circuit breaker switch 22 is embedded between the two groups of load switches. When a short circuit with an instantaneous ultra-large current occurs in the circuit, the circuit can be quickly cut off to protect the equipment from overload shock, prevent the spread of faults, and maintain the stability of the entire ring network box and power grid system. As a conductive component connecting the circuit breaker switch and the load switch, the CV busbar 22 bears the heavy responsibility of efficiently transmitting electrical energy. It uses low resistance characteristics to ensure smooth current flow, ensure that each switch device works in coordination, and realize the orderly distribution and control of electricity.

[0045] The overall layout is symmetrical and compact, with two groups of load switches 21 symmetrical about the central axis, and the circuit breaker switch 22 located in the middle, which makes the charge distribution relatively balanced. On the one hand, the symmetrical structure allows equal amounts of positive and negative charges to be regularly distributed in space. According to the principle of electric field superposition, the electric field components in each direction can offset each other to a certain extent, avoiding the excessive accumulation of electric field strength in a single direction, thereby effectively reducing the distortion of the electric field. On the other hand, the compact layout shortens the electrical distance between the components, allowing the electric field to transition relatively smoothly, just like "gathering" the scattered electric field, reducing the unevenness of the electric field. Taking adjacent load switches and circuit breaker switches as an example, the close arrangement makes the electric fields between them more coordinated, and there will be no problems of poor connection and local mutation of the electric field due to the long distance, thereby avoiding the situation where the local electric field strength is too high, ensuring that the electric field inside the equipment is in a stable and uniform state, and laying a solid foundation for the reliable operation of the equipment.

[0046] The load switch 21 includes a mounting frame 211 and a load switch drive unit 212. A load switch transmission assembly 213 is provided on the left side of the load switch drive unit 212. A moving contact 214 is hinged at the lower end of the load switch transmission assembly 213. A moving contact seat 215 is hinged at the bottom of the moving contact 214. An upper static contact 216 is provided on the upper part of the mounting frame 211. Arc extinguishing grids 217 are fixed on both sides of the upper static contact 216. An insulating umbrella skirt 218 and a grounding contact 219 are provided on the front part of the mounting frame 211.

[0047] The mounting frame 211 provides an installation foundation and positioning reference for other components of the load switch. The upper crossbeam 2111 of the load switch and the lower crossbeam 2112 of the load switch are respectively provided on the upper and lower sides thereof, which can bear the weight of each component and the mechanical force generated during operation, and maintain the stability of the entire switch structure. The load switch drive unit 212 is the power source for the load switch operation. It can receive external control signals and convert them into mechanical power to drive the load switch transmission assembly 213, thereby realizing the opening and closing action of the moving contact 214, and completing the connection and disconnection operation of the power line.

[0048] The load switch main shaft 2131 connected by the load switch drive unit 212, the transmission connector 2132 fixed on the main shaft 2131, the arc-shaped pull plate 2133 hinged at the end, and the moving contact pull plate 2134 hinged between the arc-shaped pull plates 2133. The main function of this component is to effectively transmit the power generated by the load switch drive unit 212 to the moving contact 214, and through the hinge relationship between the various components, accurately control the movement trajectory and speed of the moving contact 214, ensure that the moving contact 214 can accurately contact or separate with the static contact 216 during the opening and closing process, and achieve stable electrical connection and disconnection.

[0049] The moving contact 214 is a component in the load switch that directly participates in the circuit connection and disconnection operations. During the closing process, the moving contact 214 moves upward under the drive of the load switch transmission assembly 213, contacts the upper static contact 216, forms an electrical path, and allows the current to pass smoothly; during the opening process, the moving contact 214 moves downward and separates from the upper static contact 216, cutting off the circuit. The moving contact seat 215 provides a stable support and connection foundation for the moving contact 214, ensures the stability and accuracy of the moving contact 214 during movement, and can conduct the current on the moving contact 214 to other electrical components or the grounding system.

[0050] The upper static contact 216 is a fixed component that cooperates with the moving contact 214 to achieve electrical connection. When the moving contact 214 contacts it, a complete current path is formed, allowing electricity to be transmitted normally in the circuit. During the operation of the equipment, the upper static contact 216 needs to withstand the thermal effects and mechanical forces generated when the current passes through, and its material and structural design have good conductivity and mechanical strength. The arc extinguishing grid 217 is fixed on both sides of the upper static contact 216. Its main function is to extinguish the arc by using the special structure and material properties of the arc extinguishing grid 217 when the moving contact 214 separates from the upper static contact 216 to generate an arc during the load switch opening process. The arc extinguishing grid 217 can introduce the arc into the grid, and quickly extinguish the arc by dividing, cooling and stretching the arc, thereby protecting the contacts and other electrical components, extending the service life of the equipment, and improving the safety and reliability of the equipment.

[0051] The insulating shed 218 is installed at the front of the mounting frame 211. Its main function is to increase the creepage distance and prevent insulation breakdown caused by excessive electric field strength in a high voltage environment. The shape and material of the insulating shed 218 can effectively prevent the leakage path of current on the insulating surface and improve the insulation performance of the equipment. On the one hand, the grounding contact 219 is fixed to the insulating shed 218, playing a certain fixing and supporting role; on the other hand, the grounding contact 219 can safely introduce the current into the ground in the normal operation or failure of the equipment to ensure the safety of the equipment and personnel. The special shape of the grounding contact 219 can optimize the electric field distribution and improve the grounding effect. The left side of the grounding contact 219 is a connecting part 2191, which is fixed to the insulating shed 218, and the right part is an inverted T-shaped design, and the bottom of the inverted T is an arc shape. The connecting part 2191 firmly fixes the grounding contact 219 on the insulating shed 218, providing a stable mechanical support for the grounding contact. The inverted T-shaped structure provides better mechanical adaptability for connection with other components. Secondly, in a high voltage environment, sharp corners can easily lead to electric field concentration, while the arc-shaped design can make the electric field lines more evenly distributed around the grounding contact. This can reduce the local electric field strength and reduce the risk of corona discharge and insulation breakdown.

[0052] The lower end of the load switch 21 is provided with a test terminal 2101 and an inlet and outlet terminal 2102. The test terminal 2101 is connected to the grounding contact 219 through a copper rod, and the inlet and outlet terminal 2102 is connected to the moving contact seat 215 through a copper rod. The test terminal 2101 and the inlet and outlet terminal 2102 are provided with an insulating sleeve on the outside. The test terminal 2101 is connected to the grounding contact 219 through a copper rod. This design creates a direct connection channel for the cable withstand voltage test. In the operation and maintenance process of the power system, it is very important to regularly detect the insulation level of the cable. The previous test scheme often requires complex wiring. This design allows the operator to quickly carry out the test by simply connecting the test equipment to the test terminal 2101, which greatly simplifies the operation process, saves test preparation time, and improves the operation and maintenance efficiency. At the same time, once a fault such as leakage or short circuit occurs, the current can be quickly directed to the ground. The copper rod has good conductivity, ensuring that the resistance of the grounding path is low enough, allowing the fault current to be quickly discharged, preventing the equipment casing from being charged, protecting the operator's safety, and preventing further damage to the electrical equipment. The input and output terminals 2102 are connected to the moving contact seat 215 through the copper rod. When the circuit is turned on, such a structure can reliably transmit the electric energy from the input and output terminals to the corresponding contacts of the switch, thereby realizing the transmission of electric energy.

[0053] The program lock 24 is set on the load switch drive unit 212, which can effectively prevent the load switch from malfunctioning due to accidental touch or unauthorized operation. When the cable test is required, turn the program lock to point to the corresponding position. At this time, the load switch 21 is in the grounding position and the mechanism is in a locked state to prevent misoperation. During the test, the test terminal 2101 is connected to the high-voltage test equipment to directly apply high voltage to test the cable insulation level. After the test is completed, remove the test equipment, connect the grounded short-circuit bar, put the switch in the grounding state again, close the compartment door, and then operate the grounding switch to open and close the load switch to achieve the normal function of the three-position switch.

[0054] The circuit breaker switch 22 includes a circuit breaker switch drive unit 221 and a fixed component 222. The upper end of the circuit breaker switch drive unit 221 is connected to the circuit breaker drive main shaft 223. The drive main shaft 223 is provided with a cam connector 224 in an array. The cam connector 224 is movably connected to a vacuum bubble pull rod 225. The vacuum bubble pull rod 225 is movably arranged along the longitudinal direction. Three groups of vacuum bubbles 226 are arranged inside the fixed component 222. The lower end of the vacuum bubble pull rod 225 is fixed with a circuit breaker static contact 227. The lower end of the circuit breaker switch drive unit 221 is provided with a lower isolation transmission component 228. The lower end of the lower isolation transmission component 228 is hinged with an isolation switch moving contact 229. The bottom of the isolation switch moving contact 229 is fixed with an isolation switch moving contact seat 230. The upper part of the isolation switch moving contact seat 230 is connected to a three-phase copper rod 231, and the end of the three-phase copper rod 231 is connected to the input and output line terminals 2102.

[0055] The circuit breaker switch drive unit 221 is the core power source for the circuit breaker switch action. It is used to receive the opening and closing signals from the control system, drive the circuit breaker drive main shaft 223 connected thereto to rotate, and then start a series of subsequent actions to achieve the circuit breaker's precise control of the circuit, and ensure the reliable operation of the power line under normal and fault conditions. The cam connector 224 is movably connected to the vacuum bubble pull rod 225, and the unique profile curve of the cam is used to convert the rotational motion of the circuit breaker drive main shaft 223 into the longitudinal linear motion of the vacuum bubble pull rod 225. This motion conversion method is efficient and accurate, so that the vacuum bubble pull rod 225 can quickly drive the circuit breaker static contact 227 to achieve opening and closing actions according to the predetermined trajectory, effectively cut off or connect the circuit, and cope with various working conditions in the power system.

[0056] When opening the switch, the vacuum bubble pull rod 225 moves up quickly, driving the static contact and the moving contact in the arc extinguishing chamber to separate, using the vacuum environment to quickly extinguish the arc and reduce contact erosion; when closing the switch, it moves in the opposite direction to ensure that the static and moving contacts are in close contact, achieve reliable electrical connection, and ensure smooth passage of current. On the one hand, the fixed component 222 provides a stable installation space for the three groups of vacuum bubbles 226, protects the vacuum bubbles 226 from external mechanical impact, dust, water vapor and other interference, ensures the stability of the internal high vacuum environment, and maintains good insulation and arc extinguishing performance; on the other hand, through fixed connection with other components, such as fixing with the lower crossbeam of the load switch, the integrity and stability of the entire switchgear structure are enhanced. The vacuum bubble 226 is a key component for the circuit breaker to realize the arc extinguishing function, and the internal high vacuum environment can effectively inhibit the generation and maintenance of the arc. When an arc is generated at the moment of the circuit breaker opening, the vacuum bubble 226 uses the rapid cooling and diffusion of the arc by the vacuum to quickly extinguish the arc, prevent the arc from continuing to burn and cause damage to the contacts and other electrical components, and ensure the service life of the circuit breaker and the safe and stable operation of the power system. As one of the fixed end points of the circuit connection, the circuit breaker static contact 227 is in close contact with the isolating switch moving contact 229 in the closed state, forming a low-resistance electrical path to carry the load current during normal operation. Its material and structural design have good conductivity and wear resistance to cope with the test brought by long-term current passing and frequent opening and closing operations, ensuring efficient and stable power transmission. The lower isolation transmission component 38 is responsible for transmitting power to the isolating switch moving contact 229 and driving it to perform opening and closing operations. The isolating switch moving contact 229 works in coordination with the circuit breaker static contact 227. During the closing process, it quickly approaches the circuit breaker static contact 227 under power drive and fits tightly to complete the electrical connection; when opening, it quickly separates to cut off the current. The isolating switch moving contact seat 230 provides a solid support foundation for the isolating switch moving contact 229, ensuring that the moving contact 229 is in a stable position and moves smoothly during frequent opening and closing operations. At the same time, as an intermediate link of current conduction, it transmits the current on the disconnector moving contact 229 to the inlet and outlet terminals 2102 through the three-phase copper rod 231, ensuring the orderly output of electricity. The three-phase copper rod 231 has excellent conductivity, and efficiently and stably transmits the three-phase current collected by the disconnector moving contact seat 230 to the inlet and outlet terminals 2102, reducing the loss of electric energy during transmission, and ensuring the balanced distribution and stable transmission of the three-phase current of the power system. As the interface for external connection of the power system, the inlet and outlet terminals 2102 are convenient for connection with external cables, busbars and other power transmission lines to realize the input and output of electricity, ensure the interconnection of the entire power system, and meet the power distribution and use requirements in different application scenarios.

[0057] A grounding connection row 2221 is provided at the bottom of the fixed component 222, and three groups of T-shaped grounding contacts 2222 are provided at the upper end of the grounding connection row 2221. The grounding connection row 2221 provides a centralized and smooth discharge channel for the grounding current, and introduces leakage current and fault current that may be generated during the operation of the equipment into the earth, ensuring that the equipment casing and the surrounding environment are at a safe potential, and preventing electric shock to personnel and damage to the equipment. The three groups of T-shaped grounding contacts 2222 cooperate with the grounding connection row 2221. On the one hand, they enhance the reliability of the grounding connection. Through their special T-shaped structure, they increase the contact area with the grounding components, reduce the contact resistance, and improve the grounding effect. On the other hand, during the assembly and maintenance of the equipment, it is convenient to accurately connect with other grounding lines or components to ensure the integrity and effectiveness of the grounding system.

[0058] Working principle:

[0059] 1. Working principle of load switch

[0060] Closing operation: When the closing command is received, the load switch drive unit 212 is activated, generating mechanical power and driving the load switch transmission assembly 213 to operate. The load switch main shaft 2131 then begins to rotate at a uniform speed, driving the transmission connector 2132 rigidly connected thereto to perform circular motion synchronously. The arc-shaped pull plate 2133 hinged by the pin at the end of the transmission connector 2132 is driven to swing, and the power is smoothly transmitted to the moving contact 214 by means of the linkage transmission mechanism of the moving contact pull plate 2134. Under the action of the driving force, the moving contact 214 slides upward along the pre-designed guide rail, and finally precisely fits with the upper static contact 216 on the upper part of the mounting frame 211, forming a low-impedance electrical path, so that the current can pass through the load switch smoothly and unimpeded, successfully realizing the closing function and connecting the corresponding power line. At this time, the arc extinguishing grid 217 is in a state of alert, ready to deal with the arc that may be generated when the switch is opened.

[0061] Opening operation: Once the opening signal is received, the load switch drive unit 212 quickly reverses or starts the brake device to drive the load switch transmission component 213 to work in the opposite order of closing. The transmission components are linked in sequence to drive the moving contact 214 to move smoothly downward along the guide rail, so that it is quickly separated from the upper static contact 216, and the current path is instantly cut off. At the moment when the moving contact 214 is separated from the upper static contact 216, if an arc is generated due to factors such as electromagnetic induction, the arc extinguishing grids 217 on both sides will immediately take effect. The arc extinguishing grid 217 relies on a special metal sheet arrangement structure and material properties with high thermal conductivity and insulation to force the arc into the grid. By dividing the arc into multiple sections, efficiently cooling it, and stretching it, the arc is extinguished in a very short time, effectively protecting the contacts and other electrical components from high-temperature arc burns, ensuring that the opening process is safe and reliable with minimal impact on the system.

[0062] 2. Working principle of circuit breaker switch

[0063] Closing operation: The lower isolating transmission assembly 228 drives the isolating switch moving contact 229 to move upward steadily until the isolating switch moving contact 229 is separated from the grounding contact 2222, and the grounding operation is realized; then the lower isolating transmission assembly 228 is operated to drive the isolating switch moving contact 229 to move upward, and finally the isolating switch moving contact 229 is tightly fitted with the circuit breaker static contact 227, so as to realize the closing of the isolating switch. Subsequently, after receiving the closing instruction, the circuit breaker switch drive unit 221 drives the circuit breaker drive main shaft 223 to start rotating. The cam connectors 224 evenly distributed in an array on the main shaft 223 move precisely and synchronously with the rotation of the main shaft, and cleverly utilize the unique profile curve characteristics of the cam to efficiently convert the rotational motion of the main shaft into the longitudinal linear motion of the vacuum bubble pull rod 225. The vacuum bubble pull rod 225 is driven to move downward quickly in a linear displacement, driving the moving contact inside the arc extinguishing chamber to move toward the static contact until reliable contact is reached. Thus, a low-resistance electrical path is constructed, the closing action is successfully completed, and the power line is ensured to be connected smoothly. After the circuit breaker is closed, the three groups of vacuum bubbles 226 in the fixed component 222 work together to ensure that the surrounding environment is maintained in a high vacuum state, thereby creating ideal conditions in advance for the subsequent arc extinguishing operation that may occur.

[0064] Opening operation: When the system detects a fault or receives an opening command, the circuit breaker switch drive unit 221 drives the circuit breaker drive main shaft 223 to reverse rapidly. The cam connector 224 drives the vacuum bubble pull rod 225 to move upward at high speed, so that the moving contact inside the arc extinguishing chamber quickly leaves the static contact, and the current is cut off immediately. Due to the instantaneous current cut-off, factors such as line inductance can easily induce arc generation. At this time, the three groups of vacuum bubbles 226 play a key arc extinguishing core role. Relying on the internal high vacuum environment, the vacuum bubble 226 cools the arc ultra-fast and diffuses it efficiently, so that the arc is extinguished in a very short time (within a few milliseconds), fundamentally preventing the continuous burning of the arc from causing irreversible damage to the contacts and other electrical components, and effectively ensuring the safe operation of the power system. Subsequently, the lower isolating transmission assembly 228 drives the isolating switch moving contact 229 to move downward steadily, so that the circuit isolating switch moving contact 229 and the circuit breaker static contact 227 are quickly separated, realizing the isolating switch operation; then the lower isolating transmission assembly 228 is operated to drive the isolating switch moving contact 229 to move downward until the isolating switch moving contact 229 is in reliable contact with the grounding contact 2222, realizing the line grounding operation.

[0065] 3. Cable test: First, the operator operates the mechanism to put the load switch in the grounding state, and then carefully turns the program lock 24 to accurately point to the corresponding test position. At this time, the program lock 24 plays a forced locking function to firmly limit the load switch 21 to the grounding state, and the entire mechanism enters the locking mode synchronously, effectively preventing any misoperation from the source. Then, the operator uses a special cable to reliably connect the test terminal 2101 to the professional high-voltage test equipment, and rigorously prepares to test the cable insulation level. Thanks to the stable connection between the test terminal 2101 and the grounding contact 219 through the copper rod, it ensures that the test current can be smoothly transmitted along the preset precise path, providing a solid guarantee for obtaining accurate test data.

[0066] During the test, the locked state maintained by the program lock 24 not only strictly guarantees the accuracy and reliability of the test data, but also effectively prevents external factors from interfering with the test process, effectively avoiding major dangerous situations such as test interruption, equipment damage, and even electric shock to personnel caused by accidental touch of the switch. After the test is completed, the operator must follow the standard process, carefully remove the test equipment, accurately connect the grounding short-circuit bus, re-ground the switch, and then carefully close the compartment door. Then turn the program lock 24 again. At this time, the entire equipment status returns to normal, and the grounding switch can be operated to open the gate, successfully realizing the normal function of the three-position switch.

[0067] If a device fails, the grounding system will start instantly and quickly conduct the fault current into the earth. Relying on a low-impedance grounding path, it can effectively prevent the fault from further expanding, effectively protect the safety of the equipment and the entire power system, and minimize losses.

[0068] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A 17.5 kV ring main unit, comprising a box body (1), wherein the box body (1) comprises an outdoor box shell (11) and a ring main unit shell (12), wherein the outdoor box shell (11) and the ring main unit shell (12) are of an integrated design, an upper door plate (13) is hingedly connected to the upper end of the box body (1), an air box (2) is provided in the middle of the box body (1), a cable chamber (3) and a cable withstand voltage test chamber (4) are provided at the lower end of the air box (2), and an instrument chamber (5) is provided at the top of the box body (1), characterized in that: The interior of the gas box (2) is symmetrically arranged, two groups of load switches (21) are arranged on both sides of the interior of the gas box (2), a circuit breaker switch (22) is embedded between the load switches (21), and the circuit breaker switch (22) and the load switch (21) are connected via a CV busbar (23); The load switch (21) comprises a mounting frame (211) and a load switch drive unit (212); a load switch transmission assembly (213) is provided on the left side of the load switch drive unit (212); a moving contact (214) is hingedly connected at the lower end of the load switch transmission assembly (213); a moving contact seat (215) is hingedly connected at the bottom of the moving contact (214); an upper stationary contact (216) is provided on the upper part of the mounting frame (211); arc extinguishing grids (217) are fixed on both sides of the upper stationary contact (216); and an insulating shed (218) and a grounding contact (219) are provided on the front part of the mounting frame (211).

2. A 17.5kV ring main box according to claim 1, characterized in that: The left side of the grounding contact (219) is a connecting portion (2191) fixed to the insulating shed (218), and the right side is designed in an inverted T shape, the bottom of the inverted T shape is in an arc shape.

3. A 17.5kV ring main box according to claim 1, characterized in that: The lower end of the load switch (21) is provided with a test terminal (2101) and an inlet and outlet terminal (2102); the test terminal (2101) is connected to the grounding contact (219) via a copper rod, and the inlet and outlet terminal (2102) is connected to the moving contact seat (215) via a copper rod.

4. The 17.5kV ring main box according to claim 1, characterized in that: The load switch transmission assembly (213) comprises a load switch main shaft (2131) which is transmission-connected to the load switch drive unit (212); a transmission connecting member (2132) is fixed on the load switch main shaft (2131); an arc-shaped pull plate (2133) is hinged at the end of the transmission connecting member (2132); and a moving contact pull plate (2134) is hinged between the arc-shaped pull plates (2133).

5. The 17.5kV ring main box according to claim 1, characterized in that: The upper and lower sides of the mounting frame (211) are respectively provided with a load switch upper beam (2111) and a load switch lower beam (2112).

6. The 17.5kV ring main box according to claim 1, characterized in that: The load switch driving unit (212) is provided with a program lock (24).

7. The 17.5kV ring main box according to claim 1, characterized in that: The circuit breaker switch (22) comprises a circuit breaker switch drive unit (221) and a fixed assembly (222); the upper end of the circuit breaker switch drive unit (221) is drivingly connected to a circuit breaker drive main shaft (223); a cam connecting piece (224) is arranged in an array on the drive main shaft (223); a vacuum bubble pull rod (225) is movably connected to the cam connecting piece (224); the vacuum bubble pull rod (225) is movably arranged in the longitudinal direction; three groups of vacuum bubbles (226) are arranged inside the fixed assembly (222); the vacuum bubbles A circuit breaker static contact (227) is fixed to the lower end of the pull rod (225); a lower isolating transmission assembly (228) is provided at the lower end of the circuit breaker switch drive unit (221); an isolating switch moving contact (229) is hingedly connected to the lower end of the lower isolating transmission assembly (228); an isolating switch moving contact seat (230) is fixed to the bottom of the isolating switch moving contact (229); a three-phase copper rod (231) is connected to the upper part of the isolating switch moving contact seat (230); and the end of the three-phase copper rod (231) is connected to the input and output line terminals (2102).

8. The 17.5kV ring main box according to claim 7, characterized in that: A grounding connection row (2221) is provided at the bottom of the fixing assembly (222), and three groups of T-shaped grounding contacts (2222) are provided at the upper end of the grounding connection row (2221).

9. The 17.5kV ring main box according to claim 7, characterized in that: A flexible connection (233) is provided at the upper end of the vacuum bubble (226), and two sides of the flexible connection (233) are respectively connected to two groups of load switches (21).

10. The 17.5kV ring main box according to claim 1, characterized in that: A power source (6) is provided inside the instrument room (5), and the power source (6) is used in conjunction with a power source voltage transformer VT, and VT supplies power to the storage battery through the power source (6).

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