Highly reliable ring main unit

Abstract

The application provides a high-reliability ring main unit, comprising a gas tank, a cable chamber and a mechanism chamber, wherein the gas tank is provided with a vacuum arc-extinguishing chamber, a movable contact assembly, upper and lower static contacts selectively connected with the movable contact assembly and a grounding module; the movable contact assembly comprises a movable contact body, a high-temperature-resistant contact insert arranged on the movable contact body, a pressure adjusting spring for providing contact pressure to the movable contact body and a high-temperature-resistant heat insulation gasket arranged between the movable contact body and the pressure adjusting spring; the grounding module is sealingly installed on the inner wall of the gas tank and has a conductive lapping surface connected with an inner grounding loop and an outer grounding loop, respectively; the cable chamber comprises a side plate assembly, an impact-resistant door plate assembly and a partition plate structure for separating the cable chamber from the mechanism chamber. The application relates to the technical field of ring main units, and further relates to the field of smart grids and high-voltage power transmission and distribution equipment.

Description

Technical Field

[0001] This invention relates to the field of ring main unit technology, and further to the field of smart grids and high voltage power transmission and distribution equipment, and particularly to a highly reliable ring main unit. Background Technology

[0002] With the continuous expansion of the power distribution network and the large-scale integration of new energy power generation equipment, the short-circuit current level of the power grid is constantly rising, which puts forward higher requirements for the short-circuit tolerance and fault protection capabilities of power distribution equipment such as ring main units. To this end, a variety of improvement schemes aimed at improving the reliability of ring main units have emerged in the existing technology, such as optimizing the arc-extinguishing chamber connection method to simplify the structure, adding protective plates inside the cabinet to enhance mechanical strength, or using contact materials that are resistant to arc erosion to extend the service life.

[0003] However, existing improvement solutions mostly focus on optimizing single components or local functions, and still have systemic shortcomings when dealing with high-energy short-circuit currents and internal arc faults: On the one hand, traditional contact systems are susceptible to vibration and local overheating under high peak short-circuit currents due to electrodynamic repulsion (Holmes force), posing a risk of welding failure, and their pressure regulation mechanism may fail at high temperatures; on the other hand, conventional grounding circuit designs may lead to high resistance at connection points, posing a risk of overheating and melting under fault currents; in addition, traditional protection structures for cable compartments are mostly passively subjected to impact and ablation, lacking a systematic design to actively divert arc energy, making it difficult to effectively suppress explosive damage in a very short time, thus threatening equipment integrity and personnel safety.

[0004] Especially against the backdrop of rapid smart grid construction, large-scale grid connection of new energy sources, and the continuous development of 750 kV and above ultra-high voltage transmission systems, the short-circuit capacity of the power grid has surged, posing unprecedented challenges to the tolerance and active protection performance of distribution equipment such as ring main units under extreme operating conditions. Traditional local optimization schemes for ring main units are no longer sufficient to meet the stringent requirements of high reliability, long lifespan, and maintenance-free operation of key equipment in large-scale power grid security and defense systems.

[0005] Therefore, the inventors urgently need a highly reliable ring main unit to solve the above problems. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a highly reliable ring main unit, aiming to solve the systemic technical problems in the existing ring main unit under high short-circuit current conditions, such as easy melting and welding instability of the contact system, insufficient reliability of the grounding circuit, and lack of an active arc protection system in the cable compartment, which makes it difficult to coordinate the high tolerance and operational safety of the equipment.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a high-reliability ring main unit, comprising a gas chamber, a cable compartment, and a mechanism compartment. The gas chamber contains a vacuum interrupter, a moving contact assembly, upper and lower stationary contacts selectively engaged with the moving contact assembly, and a grounding module. The moving contact assembly includes a moving contact body, a high-temperature resistant contact insert disposed on the moving contact body, a pressure adjusting spring providing contact pressure to the moving contact body, and a high-temperature resistant heat-insulating gasket disposed between the moving contact body and the pressure adjusting spring. The grounding module is sealed and installed on the inner wall of the gas chamber. It has conductive lap surfaces that connect the internal grounding circuit and the external grounding circuit respectively. The cable compartment includes a side plate assembly, an impact-resistant door panel assembly, and a partition structure that separates the cable compartment from the mechanism compartment. The side plate assembly includes an outer outer plate, an intermediate layer forming an air gap, a high-temperature resistant plate, and a reinforcing plate arranged sequentially from the outside to the inside. The partition structure has a pressure relief channel. The impact-resistant door panel assembly includes an outer door panel, a first air layer, a first high-temperature resistant plate, a second air layer, and an inner metal plate that serves as a preset arc initiation point, arranged sequentially from the outside to the inside, to form a systematic internal arc protection system.

[0008] Based on the above, the beneficial effects of a high-reliability ring main unit (RNB) are to solve the systemic technical problems in existing RNBs under high short-circuit current conditions, such as the easy melting and instability of the contact system, insufficient reliability of the grounding circuit, and the lack of an active arc protection system in the cable compartment, making it difficult to coordinate the high tolerance and operational safety of the equipment. These problems are mainly reflected in:

[0009] 1. This invention, through a high-temperature resistant contact insert set on the moving contact body, a pressure regulating spring that provides contact pressure to the moving contact body, and a high-temperature resistant heat-insulating pad set between the moving contact body and the pressure regulating spring, achieves the following: under high peak short-circuit current, the high-temperature resistant heat-insulating pad blocks the transfer of heat to the pressure regulating spring, ensuring the elasticity of the pressure regulating spring and the stability of the pressure output, thereby ensuring the stability of the contact pressure between the moving and stationary contacts and the reliability of the contact resistance, fundamentally avoiding welding and arcing in the contact system;

[0010] 2. This invention achieves a reliable, low-resistance, and sealed connection between the grounding circuit inside the cabinet and the grounding circuit outside the cabinet through the conductive lap surface of the grounding module and its conductive lap surface, which is sealed and installed on the inner wall of the gas box. This significantly reduces the resistance of the grounding circuit, ensures that the short-circuit fault current can be safely and effectively discharged, and eliminates the safety hazard of grounding failure caused by overheating and melting of the connection point.

[0011] 3. This invention achieves multi-layered, systematic protection against internal arc faults through a side panel assembly consisting of an outer side panel, an intermediate layer forming an air gap, a high-temperature resistant plate, and a reinforcing plate arranged sequentially; an impact-resistant door panel assembly consisting of an outer door panel, a first air layer, a first high-temperature resistant plate, a second air layer, and an inner metal plate serving as a preset arc initiation point; and a pressure relief channel opened in the partition structure. The composite structure composed of the outer side panel, intermediate layer, high-temperature resistant plate, and reinforcing plate, together with the multi-layered heat insulation structure composed of the outer door panel, first air layer, first high-temperature resistant plate, second air layer, and inner metal plate, jointly resist explosion impacts and high-temperature ablation. By setting the inner metal plate as a preset arc initiation point, the arc energy is guided to act preferentially on this point, and the gas and pressure generated by the arc are actively diverted and released through the pressure relief channel, thereby transforming passive damage absorption into active diversion and protection, and synergistically ensuring the integrity of the equipment structure and high operational safety.

[0012] Furthermore, an integrated mechanism chamber base is provided between the cable chamber and the mechanism chamber, and a top high-temperature resistant plate and a front high-temperature resistant plate are installed on the side of the mechanism chamber base facing the cable chamber.

[0013] Based on the above, the beneficial effects of the mechanism chamber base support are that it eliminates the splicing gaps and excessive connection points present in traditional split base supports, significantly enhancing its structural strength and integrity. Simultaneously, it fundamentally reduces the energy leakage path caused by the assembly interface between the cable chamber and the mechanism chamber, improving the physical isolation and sealing effect between the two functional chambers. The beneficial effect of installing a top high-temperature resistant plate on the side of the mechanism chamber base support facing the cable chamber is that it directly blocks the ablation and damage to the body material of the mechanism chamber base support from high-temperature arcs, hot air currents, and molten metal droplets that may escape upwards from inside the cable chamber. The beneficial effect of installing a front high-temperature resistant plate on the side of the mechanism chamber base support facing the cable chamber is that it blocks the direct ablation and impact of the high temperature and impact of the arc generated from the rear side of the cable chamber on the body material of the mechanism chamber base support. Together with the top high-temperature resistant plate, it constitutes multi-directional protection for the mechanism chamber base support, ensuring its functional reliability as a key partition.

[0014] Furthermore, the high-temperature resistant contact insert on the moving contact body is a copper-tungsten alloy insert, and the closing end of the lower stationary contact is provided with a tungsten alloy insert. When closing, the copper-tungsten alloy insert and the tungsten alloy insert are in face-to-face contact.

[0015] Based on the above, the beneficial effects of the copper-tungsten alloy insert are that it utilizes the material's high melting point, high hardness, and excellent resistance to arc erosion, allowing it to withstand the high-temperature arc generated during short-circuit interruption, preventing the contact material from melting or severely burning due to overheating, and ensuring the electrical life and contact reliability of the contacts under harsh operating conditions. The beneficial effects of the tungsten alloy insert are that, together with the copper-tungsten alloy insert, it forms a key contact pair in the main current path. The tungsten alloy insert leverages the advantages of tungsten alloy's extremely high melting point and high-temperature stability, maintaining structural integrity and shape stability even under the instantaneous high temperatures caused by short-circuit current. The fixed contact tip is prevented from deforming or melting due to thermal erosion, ensuring the long-term availability and geometric accuracy of the closing contact surface. The beneficial effect of the copper-tungsten alloy insert and the tungsten alloy insert being face-to-face overlapping is that it changes the traditional point-line contact to a large-area planar contact, which significantly increases the effective conductive area between the moving and stationary contacts when closing, reduces the current density at the contact point and the resulting electrodynamic repulsion force (Holmes force), thereby suppressing harmful vibration and local overheating of the contact system, and providing a key structural guarantee for the switch to achieve stable contact and reliable opening under high short-circuit current.

[0016] Furthermore, the moving contact assembly is provided with at least four copper-tungsten alloy inserts, and the total closing contact area of ​​the four copper-tungsten alloy inserts when the circuit is closed is not less than 6 square centimeters.

[0017] Based on the above, the beneficial effects of at least four copper-tungsten alloy inserts are that, through a multi-point distributed layout, multiple parallel current paths are formed with the stationary contact during closing, significantly improving the uniformity of current distribution within the contact system, reducing current concentration and thermal load at individual contact points, thereby synergistically enhancing the thermal and mechanical stability of the entire switch when carrying large currents; the beneficial effect of a total closing contact area of ​​not less than 6 square centimeters is that, based on the arrangement of multiple copper-tungsten alloy inserts, the total conductive contact area between the moving and stationary contacts is increased to a clear technical threshold (≥6 cm²). Through extensive experiments, this specific design significantly reduces the overall current density in the contact area and the resulting electrodynamic repulsion force (Holmes force), providing a key quantitative structural guarantee for effectively suppressing contact vibration, preventing local overheating and welding, and ensuring reliable opening under short-circuit peak current.

[0018] Furthermore, the pressure regulating spring is made of spring steel with added zirconium, and the high-temperature resistant heat insulation gasket is a mica gasket.

[0019] Based on the above, the beneficial effects of making the pressure regulating spring from spring steel with added zirconium are that zirconium enhances the high-temperature performance of the spring steel, allowing the spring to maintain its elastic modulus and mechanical strength even under high-temperature environments caused by short-circuit current (such as above 1000℃), preventing the elastic force from weakening due to high-temperature softening, thereby ensuring continuous and stable contact pressure between the moving and stationary contacts under harsh working conditions. The beneficial effects of using mica gaskets for high-temperature resistant insulation are that mica's excellent high-temperature resistance and insulation properties (such as continuous temperature resistance of 850℃ and gap temperature resistance of 1050℃) construct an effective thermal barrier between the moving contact body and the pressure regulating spring, preventing the direct transmission of high temperatures generated by the contact during current flow or under the action of electric arc to the pressure regulating spring, ensuring that the spring's operating temperature remains within its safe range.

[0020] Furthermore, the mounting surface of the grounding module is provided with a sealing ring, and the conductive part of the grounding module is a cuboid conductor with a cross-sectional area of ​​3.4 square centimeters. The two ends of the cuboid conductor form the conductive overlapping surface, and the distance between the two conductive overlapping surfaces is 2.3 centimeters.

[0021] Based on the above, the beneficial effects of the sealing ring are that it forms a reliable seal at the installation interface between the grounding module and the inner wall of the gas box, preventing leakage of the insulating medium inside the gas box and ensuring the overall sealing integrity of the ring main unit gas box. At the same time, this physical isolation also prevents external environmental moisture or pollutants from entering through the installation gaps. The beneficial effect of the cuboid conductor is that it provides a low-impedance conductive path with sufficient cross-section, stable resistance value, and easy calculation and control for the grounding circuit. This design is the key structural foundation to ensure that it can withstand the specified short-time withstand current (such as 31.5kA / 4s) without thermal damage. The beneficial effect of the 2.3 cm distance between the two conductive overlapping surfaces is that while meeting the necessary electrical insulation and mechanical installation space requirements, it controls the resistance value of the grounding module itself, so that the heat and temperature rise generated under the specified short-time withstand current are within a safe and controllable range. This is one of the core dimensional parameters for achieving its predetermined electrical performance.

[0022] Furthermore, the outer side plate has a portion protruding towards the inner side of the cable compartment, the middle layer is an air layer formed between the outer side plate and the high-temperature resistant plate, and the reinforcing plate is attached to the inner surface of the high-temperature resistant plate.

[0023] Based on the above, the beneficial effect of the outer panel having a portion protruding towards the inner side of the cable compartment is that, through its own protruding structure, it naturally forms an installation positioning foundation and necessary physical interval with the subsequent layer structure without the need for additional connectors or complex assembly. This provides key structural support and spatial conditions for constructing a composite protective layer including air gaps. The beneficial effect of the air layer is that, utilizing the low thermal conductivity of air, a static heat insulation barrier is constructed between the outer panel and the high-temperature resistant plate, effectively blocking the direct heat conduction from the high temperature generated when an arc fault occurs inside the cable compartment to the outside of the cabinet, significantly reducing the temperature rise of the outer panel. The beneficial effect of the reinforcing plate being attached to the inner surface of the high-temperature resistant plate is that it provides direct mechanical reinforcement to the high-temperature resistant plate, together forming a composite plate structure with higher bending and impact resistance. This enhances the structural rigidity of the cable compartment sidewall when subjected to the pressure wave impact of an internal arc explosion, preventing permanent deformation or cracking.

[0024] Furthermore, the impact-resistant door panel assembly is disposed on the side of the cable compartment near the mechanism compartment. A reinforcing rib is provided on the inner side of the outer door panel. The first high-temperature resistant plate is installed on the reinforcing rib to form the first air layer. The inner metal plate is installed on the first high-temperature resistant plate via a shim mounting bracket to form the second air layer. A side high-temperature resistant plate is disposed inside the left and right side frames of the impact-resistant door panel assembly within the cable compartment. The left and right edges of the inner metal plate are snapped onto the side high-temperature resistant plate. The upper edge of the inner metal plate is snapped onto the side of the mechanism compartment base facing the cable compartment. The gap between the inner metal plate and the side high-temperature resistant plate is less than 0.2 cm, and the gap between the inner metal plate and the mechanism compartment base is less than 0.2 cm.

[0025] Based on the above, the beneficial effects of the reinforcing ribs are that they provide additional structural support and stiffness enhancement for the outer door panel, significantly improving its mechanical strength to resist the shock wave pressure generated by the internal arc explosion, and effectively preventing the outer door panel from undergoing irreversible plastic deformation or being blown open under fault impact; the beneficial effect of the first air layer is that by using the reinforcing ribs as support and spacer components, a stable first air layer is formed between the first high-temperature resistant plate and the outer door panel. The first air layer, together with the second air layer closer to the inside of the cable compartment, constitutes a double-layer heat insulation system, effectively attenuating the transfer of extreme high-temperature heat from the inside to the outer door panel during an internal arc fault; the beneficial effect of the second air layer is that by using the raised mounting piece as a precise spacer, a stable second air layer is formed between the inner metal plate and the first high-temperature resistant plate. The second air layer, as the first heat insulation barrier, directly blocks the heat generated by the inner metal plate during an internal arc fault. The extreme high temperature of the electric arc is transmitted to the inner structure, positioning the inner metal plate as the preset arc initiation point. The beneficial effect of the side high-temperature resistant plate is to provide a continuous high-temperature resistant protective boundary on both sides of the impact-resistant door panel assembly. It connects with the protective structure of the side panel assembly and together forms a complete barrier against electric arc impact and high-temperature ablation on the side of the cable chamber, preventing fault arcs and high-temperature molten metal droplets from escaping through the lateral gaps. The beneficial effect of making the gap between the inner metal plate, the side high-temperature resistant plate, and the bottom support of the mechanism chamber less than 0.2 cm is that by controlling this critical gap within the extremely small range of ≤0.2 cm, the possibility of high-temperature plasma, combustion products, and molten metal droplets generated during internal arc faults being ejected and escaped from the gap between the edge of the inner metal plate and the surrounding fixed structure is minimized. This ensures the tightness of the fault protection system at the interface and is a key size guarantee for achieving active guidance and energy containment.

[0026] Furthermore, the partition structure includes a middle partition and a rear bottom sealing plate, the pressure relief channel is a pressure relief hole opened on the rear bottom sealing plate, and a pressure relief plate is installed on the pressure relief hole.

[0027] Based on the above, the beneficial effects of the middle partition and the rear bottom sealing plate are as follows: the combination of the middle partition and the rear bottom sealing plate forms a clear physical separation and support framework in the cable compartment, which not only achieves effective isolation between the cable compartment and the mechanism compartment to prevent the spread of faults, but also provides a reliable structural foundation for the installation of other functional components and the opening of pressure relief channels. The beneficial effect of the pressure relief hole is that the channel opened in the rear bottom sealing plate provides a controlled outward emission path for the high-temperature and high-pressure gas generated inside the cable compartment due to the arc fault, so that the explosive energy can be directed to the expected pressure relief area, rather than randomly impacting other weak parts of the cabinet. The beneficial effect of installing a pressure relief plate on the pressure relief hole is that the pressure relief plate remains sealed under normal operating conditions, maintaining the protection level of the cable compartment and the isolation from the environment. When the internal arc fault causes a sudden increase in pressure, the pressure relief plate can be opened or ruptured quickly, thereby opening the pressure relief hole in time, realizing rapid pressure relief, and actively releasing pressure to protect the main cabinet structure from explosive damage.

[0028] Furthermore, a bowl-shaped protective plate protruding from the inside out is provided on the rear inner side of the cable compartment, and the bowl-shaped protective plate is tightly fixed to the rear frame of the cable compartment.

[0029] Based on the above, the beneficial effects of the bowl-shaped protective plate are that, through its unique bowl-shaped structure that bulges outward from the inside, it transforms the originally flat protective plate into a curved shell structure with higher bending stiffness and impact resistance, significantly enhancing the mechanical strength of the rear wall of the cable chamber when subjected to the shock wave of an internal electric arc explosion, and effectively resisting deformation or cracking caused by impact. The beneficial effect of the bowl-shaped protective plate being tightly fixed to the rear frame of the cable chamber is that it forms a continuous and stable mechanical connection interface and a reliable sealing boundary between the two, preventing high-pressure gas, combustion smoke and high-temperature molten material from escaping from the joint, and ensuring the integrity and airtightness of the rear protection of the cable chamber.

[0030] To make the above features of the present invention and the objectives to be achieved clearer, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Attached Figure Description

[0031] Figure 1 : This is a perspective view of the present invention;

[0032] Figure 2 : This is a schematic diagram of the moving contact assembly of the present invention;

[0033] Figure 3 : This is a half-side view of the moving contact body of the present invention;

[0034] Figure 4 : This is a cross-sectional view of the lower stationary contact of the present invention;

[0035] Figure 5 : This is a schematic diagram of the grounding module of the present invention;

[0036] Figure 6 : This is a cross-sectional view of the grounding module of the present invention;

[0037] Figure 7 : This is a schematic diagram showing the positions of the two conductive overlapping surfaces of the present invention;

[0038] Figure 8 : This is a schematic diagram of the cable compartment of the present invention;

[0039] Figure 9 : This is a cross-sectional structural schematic diagram of the side panel assembly of the present invention;

[0040] Figure 10 : This is a schematic diagram of the base of the mechanism chamber of the present invention;

[0041] Figure 11 : This is a schematic diagram of the impact-resistant door panel assembly of the present invention;

[0042] Figure 12 : This is a cross-sectional structural diagram of the impact-resistant door panel assembly of the present invention.

[0043] Reference numerals: 1-Gas box, 11-Vacuum interrupter, 12-Moving contact assembly, 121-Moving contact body, 122-High-temperature resistant contact insert, 1221-Copper-tungsten alloy insert, 123-Pressure adjusting spring, 124-High-temperature resistant heat insulation gasket, 13-Upper stationary contact, 14-Lower stationary contact, 141-Tungsten alloy insert, 15-Grounding module, 151-Conductive lap surface, 152-Sealing ring, 2-Cable chamber, 21-Side plate assembly, 211-Outer side plate, 212-Intermediate layer, 213-High-temperature resistant plate, 214-Strengthened... 22-Impact-resistant door panel assembly, 221-Outer door panel, 222-First air layer, 223-First high-temperature resistant plate, 224-Second air layer, 225-Inner metal plate, 226-Reinforcing rib, 227-Elevation mounting piece, 23-Partition structure, 231-Pressure relief channel, 2311-Pressure relief hole, 2312-Pressure relief plate, 232-Middle partition, 233-Rear bottom sealing plate, 24-Bowl-shaped protective plate, 25-Mechanical chamber bottom support, 251-Top high-temperature resistant plate, 252-Front high-temperature resistant plate, 26-Side high-temperature resistant plate, 3-Mechanical chamber. Detailed Implementation

[0044] See Figures 1-12 As shown,

[0045] This invention provides a high-reliability ring main unit, comprising a gas chamber 1, a cable compartment 2, and a mechanism compartment 3. The gas chamber 1 houses a vacuum interrupter 11, a moving contact assembly 12, an upper stationary contact 13 and a lower stationary contact 14 selectively engaged with the moving contact assembly 12, and a grounding module 15. The moving contact assembly 12 includes a moving contact body 121, a high-temperature resistant contact insert 122 disposed on the moving contact body 121, a pressure adjusting spring 123 providing contact pressure to the moving contact body 121, and a high-temperature resistant heat-insulating gasket 124 disposed between the moving contact body 121 and the pressure adjusting spring 123. The grounding module 15 is sealed and installed on the inner wall of the gas chamber 1 and has connections to the interior of the cabinet. The conductive lap surface 151 of the grounding circuit and the external grounding circuit of the cabinet, the cable chamber 2 includes a side plate assembly 21, an impact-resistant door panel assembly 22 and a partition structure 23 that separates the cable chamber 2 from the mechanism chamber 3. The side plate assembly 21 includes an outer outer plate 211, an intermediate layer 212 forming an air gap, a high-temperature resistant plate 213 and a reinforcing plate 214 arranged sequentially from the outside to the inside. The partition structure 23 is provided with a pressure relief channel 231. The impact-resistant door panel assembly 22 includes an outer door panel 221, a first air layer 222, a first high-temperature resistant plate 223, a second air layer 224 arranged sequentially from the outside to the inside and an inner metal plate 225 serving as a preset arc initiation point, so as to form a systematic internal arc protection system.

[0046] In this embodiment, the high-temperature resistant heat insulation pad 124 is made of HP-8 mica material, which has a continuous temperature resistance of up to 850℃ and a gap temperature resistance of up to 1050℃. It can effectively prevent the high temperature generated by the current flow of the contacts from being transmitted to the pressure regulating spring 123. The pressure regulating spring 123 is made of spring steel with 0.08% zirconium added, which can withstand high temperature environments above 1000℃, ensuring that it does not soften or lose its elasticity under the high temperature caused by short circuit current. Through the synergistic effect of the heat insulation pad and the high-temperature spring, the clamping force between the moving and stationary contacts is sufficient to offset the electrodynamic repulsion force (Holmes force) generated by the short circuit current, thereby avoiding the sudden increase in resistance, contact welding and arcing caused by insufficient contact pressure.

[0047] In this embodiment, the high-temperature resistant contact insert 122 on the moving contact body 121 is a copper-tungsten alloy insert 1221, and the closing end of the lower stationary contact 14 is provided with a tungsten alloy insert 141. When closing, the copper-tungsten alloy insert 1221 and the tungsten alloy insert 141 are in face-to-face contact.

[0048] In this embodiment, the copper-tungsten alloy insert 1221 and the tungsten alloy insert 141 are connected face-to-face. Compared with the traditional point-to-face connection, this method significantly increases the effective conductive contact area and significantly changes the magnetic field distribution generated when the short-circuit current flows through the contact surface, thereby reducing the electrodynamic repulsion force (i.e., Holm force) acting on the moving contact. This design, in principle, suppresses the harmful vibration of the contact under the short-circuit peak current and is one of the key structural improvements to avoid welding and arcing phenomena.

[0049] In this embodiment, the moving contact assembly 12 is provided with at least four copper-tungsten alloy inserts 1221, and the total closing contact area of ​​the four copper-tungsten alloy inserts 1221 when the circuit is closed is not less than 6 square centimeters.

[0050] In this embodiment, the pressure regulating spring 123 is made of spring steel with added zirconium, and the high-temperature resistant heat insulation gasket 124 is a mica gasket.

[0051] In this embodiment, the mounting surface of the grounding module 15 is provided with a sealing ring 152, and the conductive part of the grounding module 15 is a cuboid conductor with a cross-sectional area of ​​3.4 square centimeters. The two ends of the cuboid conductor form the conductive overlapping surface 151, and the distance between the two conductive overlapping surfaces 151 is 2.3 centimeters.

[0052] In this embodiment, the conductor cross-sectional area (3.4 square centimeters) of the grounding module 15 is consistent with the overlapping surface area. This critical dimension is designed based on the thermal stability requirements of short-time withstand current. Specifically, the minimum cross-sectional area S of the cuboid conductor must satisfy the formula: Where I is the short-time withstand current value (31.5kA), t is the withstand time (4s), Δθ is the allowable temperature rise of the conductor, and a is a coefficient related to the conductor material (copper). Calculation and verification using the industry-known formula show that the cuboid conductor structure with a cross-sectional area of ​​3.4 square centimeters and a length of 2.3 centimeters in this embodiment far exceeds the standard requirements and can reliably withstand the stringent test of 31.5kA / 4s. This fundamentally solves the safety failure problem caused by high resistance and overheating of connection points in traditional grounding circuits.

[0053] In this embodiment, the outer side plate 211 has a portion protruding towards the inside of the cable chamber 2, the middle layer 212 is an air layer formed between the outer side plate 211 and the high temperature resistant plate 213, and the reinforcing plate 214 is attached to the inner surface of the high temperature resistant plate 213.

[0054] In this embodiment, the intermediate layer 212 is an air layer with a thickness of 1 cm, which utilizes the thermal insulation properties of air to form the first thermal barrier; the high-temperature resistant plate 213 and the reinforcing plate 214 together form the composite protective body; the high-temperature resistant plate 213 is made of HP-8 mica board with a thickness of 0.2 cm; in order to ensure sufficient protection for key areas inside the cable room (such as cable joints and the area around the sleeve) in the vertical installation state, the radial distance between the farthest edge of the high-temperature resistant plate 213 and the preset cable sleeve installation center point in the cable room is designed to be greater than 51 cm after installation; the radial distance between the farthest edge of the reinforcing plate 214 and the center point is greater than 66 cm; this composite structure and its sufficient radial coverage can effectively resist the instantaneous high temperature of thousands of degrees and the explosive shock wave generated by the arc fault inside the cable room, preventing the side plate from being burned through or cracked.

[0055] In this embodiment, the impact-resistant door panel assembly 22 is disposed on the side of the cable chamber 2 near the mechanism chamber 3. The inner side of the outer door panel 221 is provided with a reinforcing rib 226. The first high-temperature resistant plate 223 is installed on the reinforcing rib 226 to form the first air layer 222. The inner metal plate 225 is installed on the first high-temperature resistant plate 223 through a shim mounting piece 227 to form the second air layer 224. The cable chamber 2 is provided with a side high-temperature resistant plate 26 inside the left and right side frames of the impact-resistant door panel assembly 22. The left and right side edges of the inner metal plate 225 are snapped onto the side high-temperature resistant plate 26. The upper edge of the inner metal plate 225 is snapped onto the side of the mechanism chamber base 25 facing the cable chamber 2. The gap between the inner metal plate 225 and the side high-temperature resistant plate 26 is less than 0.2 cm. The gap between the inner metal plate 225 and the mechanism chamber base 25 is less than 0.2 cm.

[0056] In this embodiment, the innermost inner metal plate 225 is designed as a preset arc initiation point; when an arc fault occurs inside the cable room, the arc is guided to the surface of the inner metal plate 225 to burn; the second air layer 224, the first high-temperature resistant plate 223, and the first air layer 222 on the outside together constitute a highly efficient multi-layer heat insulation system, which restricts most of the extreme high temperature generated by the arc to the vicinity of the inner metal plate 225 and attenuates it layer by layer; the outer door panel 221 therefore mainly bears the heat radiation and pressure impact of the high-temperature gas, and with the rigidity provided by the reinforcing rib 226, it can be ensured that it only undergoes slight deformation and will not be burned through or blown away, realizing the transformation of the protection concept from passive bearing to active guidance and isolation.

[0057] In this embodiment, the partition structure 23 includes a middle partition 232 and a rear bottom sealing plate 233. The pressure relief channel 231 is a pressure relief hole 2311 opened on the rear bottom sealing plate 233, and a pressure relief plate 2312 is installed on the pressure relief hole 2311.

[0058] In this embodiment, a bowl-shaped protective plate 24 protruding from the inside out is provided on the inner rear side of the cable chamber 2, and the bowl-shaped protective plate 24 is tightly fixed to the rear frame of the cable chamber 2.

[0059] In this embodiment, an integrated mechanism chamber base 25 is provided between the cable chamber 2 and the mechanism chamber 3. A top high-temperature resistant plate 251 and a front high-temperature resistant plate 252 are installed on the side of the mechanism chamber base 25 facing the cable chamber 2.

[0060] In this embodiment, the mechanism chamber base 25 adopts an integrated design, which significantly reduces the assembly gap between the cable chamber 2 and the mechanism chamber 3; the upper edge of the inner metal plate 225 is fastened to the mechanism chamber base 25, and together with the top high-temperature resistant plate 251 and the front high-temperature resistant plate 252, they jointly seal the key interface between the top front of the cable chamber and the mechanism chamber, effectively blocking the arc energy and molten metal from entering the mechanism chamber 3 along this path, and ensuring the safety of the operating mechanism.

[0061] In this embodiment, the high-temperature resistant plate 213 constituting the side panel assembly 21, the first high-temperature resistant plate 223 of the impact-resistant door panel assembly 22, the top high-temperature resistant plate 251 and the front high-temperature resistant plate 252 on the bottom support 25 of the mechanism chamber, and the side high-temperature resistant plate 26 are all made of HP-8 mica board with a thickness of 0.2 cm. This material has excellent performance in continuously withstanding high temperatures of 850℃ and gap temperature resistance of up to 1050℃, providing a unified and reliable high-temperature isolation barrier for the arc protection system inside the cable chamber 2.

[0062] The above description is merely the optimal embodiment of the present invention and is not intended to limit the present invention. Any modifications or substitutions made by those skilled in the art without departing from the essence and scope of protection of the present invention should also be within the scope of protection of the present invention.

Claims

1. A high-reliability ring main unit, comprising an air chamber (1), a cable compartment (2), and a mechanism compartment (3), characterized in that: The gas box (1) is equipped with a vacuum interrupter (11), a moving contact assembly (12), an upper stationary contact (13) and a lower stationary contact (14) selectively engaged with the moving contact assembly (12), and a grounding module (15). The moving contact assembly (12) includes a moving contact body (121), a high-temperature resistant contact insert (122) disposed on the moving contact body (121), a pressure adjusting spring (123) providing contact pressure to the moving contact body (121), and a high-temperature resistant heat insulation gasket (124) disposed between the moving contact body (121) and the pressure adjusting spring (123). The grounding module (15) is sealed and installed on the inner wall of the gas box (1) and has conductive contact surfaces that connect the grounding circuit inside the cabinet and the grounding circuit outside the cabinet, respectively. (151) The cable chamber (2) includes a side plate assembly (21), an impact-resistant door panel assembly (22), and a partition structure (23) that separates the cable chamber (2) from the mechanism chamber (3). The side plate assembly (21) includes an outer side plate (211), an intermediate layer (212) forming an air gap, a high-temperature resistant plate (213), and a reinforcing plate (214) arranged sequentially from the outside to the inside. The partition structure (23) has a pressure relief channel (231). The impact-resistant door panel assembly (22) includes an outer door panel (221), a first air layer (222), a first high-temperature resistant plate (223), a second air layer (224), and an inner metal plate (225) serving as a preset arc initiation point, in order to form a systematic internal arc protection system. An integrated mechanism chamber base (25) is provided between the cable chamber (2) and the mechanism chamber (3). The mechanism chamber base (25) is equipped with a top high-temperature resistant plate (251) and a front high-temperature resistant plate (252) on the side of the mechanism chamber base (25) facing the cable chamber (2). The impact-resistant door panel assembly (22) is located on the side of the cable chamber (2) near the mechanism chamber (3). The inner side of the outer door panel (221) is provided with a reinforcing rib (226). The first high-temperature resistant plate (223) is installed on the reinforcing rib (226) to form the first air layer (222). The inner metal plate (225) is installed on the first high-temperature resistant plate (223) through a raised mounting piece (227) to form the second air layer (224). The cable chamber (2) is provided with a side high-temperature resistant plate (26) on the inner side of the left and right frames of the impact-resistant door panel assembly (22). The left and right edges of the inner metal plate (225) are snapped onto the side high-temperature resistant plate (26). The upper edge of the inner metal plate (225) is snapped onto the side of the mechanism chamber base (25) facing the cable chamber (2).

2. The high-reliability ring main unit according to claim 1, characterized in that: The high-temperature resistant contact insert (122) on the moving contact body (121) is a copper-tungsten alloy insert (1221), and the closing end of the lower stationary contact (14) is provided with a tungsten alloy insert (141). When closing, the copper-tungsten alloy insert (1221) and the tungsten alloy insert (141) are in face-to-face contact.

3. A high-reliability ring main unit according to claim 2, characterized in that: The moving contact assembly (12) is provided with at least four copper-tungsten alloy inserts (1221), and the total closing contact area of ​​the four copper-tungsten alloy inserts (1221) when closed is not less than 6 square centimeters.

4. A high-reliability ring main unit according to claim 1, characterized in that: The pressure regulating spring (123) is made of spring steel with added zirconium, and the high-temperature heat-insulating gasket (124) is a mica gasket.

5. A high-reliability ring main unit according to claim 1, characterized in that: The mounting surface of the grounding module (15) is provided with a sealing ring (152). The conductive part of the grounding module (15) is a cuboid conductor with a cross-sectional area of ​​3.4 square centimeters. The two ends of the cuboid conductor form the conductive overlapping surface (151), and the distance between the two conductive overlapping surfaces (151) is 2.3 centimeters.

6. A high-reliability ring main unit according to claim 1, characterized in that: The outer plate (211) has a portion that protrudes into the cable chamber (2), the middle layer (212) is an air layer formed between the outer plate (211) and the high temperature resistant plate (213), and the reinforcing plate (214) is attached to the inner surface of the high temperature resistant plate (213).

7. A high-reliability ring main unit according to claim 1, characterized in that: The gap between the inner metal plate (225) and the side high-temperature resistant plate (26) is less than 0.2 cm, and the gap between the inner metal plate (225) and the bottom support (25) of the mechanism chamber is less than 0.2 cm.

8. A high-reliability ring main unit according to claim 1, characterized in that: The partition structure (23) includes a middle partition (232) and a rear bottom sealing plate (233). The pressure relief channel (231) is a pressure relief hole (2311) opened on the rear bottom sealing plate (233). A pressure relief plate (2312) is installed on the pressure relief hole (2311).

9. A high-reliability ring main unit according to claim 8, characterized in that: A bowl-shaped protective plate (24) protruding from the inside to the outside is provided on the inner rear side of the cable chamber (2), and the bowl-shaped protective plate (24) is tightly fixed to the rear frame of the cable chamber (2).

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