A fully sealed outdoor ring main unit with a centralized cable sealing junction box

Abstract

This application relates to a fully sealed outdoor ring main unit with a centralized cable sealing junction box, belonging to the field of power equipment technology. It includes a main enclosure, within which a vertical partition divides the enclosure into an equipment room, a control room, and a cable room. A centralized cable sealing junction box is fixedly installed in the cable room. An inlet hole is provided in the bottom plate of the cable room, through which cables entering and exiting the ring main unit enter the junction box. The junction box contains a sealing module layer, an expansion sealing layer, and a fire-resistant sheath. A drainage tank is located at the bottom of the junction box. An installation plate is provided between the sealing module layer and the expansion sealing layer. A connecting hole is provided on the installation plate, and a liquid level clamping module is installed. When the expansion sealing layer encounters water, it expands and is squeezed out through the connecting hole, pushing a lever mechanism to actuate, driving the sealing module layer to generate additional clamping force on the cable. This application achieves zero cable hole clearance in the main enclosure, centralized sealing, and adaptive linkage clamping, significantly improving the protection level and anti-condensation capability of the ring main unit.

Description

Technical Field

[0001] This application relates to the field of power equipment technology, and in particular to a fully sealed outdoor ring main unit with a centralized cable sealing junction box. Background Technology

[0002] Outdoor ring main units, as key node equipment in power distribution network systems, undertake important functions such as power distribution, line protection and operation control, and are widely used in urban power distribution networks, industrial parks, residential communities and outdoor power distribution lines.

[0003] To address the sealing issue of cable entry and exit holes in outdoor ring main units, a common approach is to install independent sealing devices at each cable entry hole on the bottom plate of the ring main unit. These devices may include sealing rings, fire-resistant sealing mud, water-swellable sealant, or mechanically tightened sealing components to fill and seal the gap between the cable and the hole. Some solutions incorporate independent drainage channels and pumps inside the unit to actively drain any water that seeps into the unit.

[0004] However, existing ring main units have multiple scattered cable entry holes on the bottom plate of the main unit, and each hole is sealed independently. This results in the overall protection level being limited by the weakest sealing point. If any sealing point fails, moisture will enter. Furthermore, it is difficult to monitor and maintain the status of multiple sealing points in a centralized manner. Summary of the Invention

[0005] The purpose of this application is to overcome the above-mentioned technical problems and provide a fully sealed outdoor ring network box with a centralized cable sealing junction box.

[0006] A fully sealed outdoor ring main unit with a centralized cable sealing junction box includes a main unit. The main unit is divided into an equipment room, a control room, and a cable room by vertical partitions. Each of the equipment room, control room, and cable room has an openable door, and the inner edge of each door is equipped with a sealing strip to create an airtight seal. A centralized cable sealing junction box is installed in the cable room. The bottom plate of the cable room has an inlet hole for cable entry. Cables entering and exiting the ring main unit pass through this inlet hole into the junction box and then exit into the main unit. The bottom plates of the equipment room and control room are both complete panels without cable entry holes. A sealing module layer and an expansion joint are arranged vertically from top to bottom inside the junction box. The sealing layer and the flame-retardant layer constitute a three-layer sealing structure. A drain tank is located at the bottom of the transfer box, which contains a liquid level sensor and a drain pump. The outlet of the drain pump is connected to a drain pipe via a one-way valve, and the drain pipe extends to the outside of the main box. An installation plate is located between the sealing module layer and the expansion sealing layer inside the transfer box. The installation plate has a connecting hole for the cable to pass through. A liquid level clamping module is installed on the installation plate. The liquid level clamping module includes a driving component and a lever mechanism. One end of the lever mechanism is connected to the driving component, and the other end abuts against the sealing module layer. When the expansion sealing layer expands upon contact with water, it is squeezed out from the connecting hole and pushes the lever mechanism to drive the sealing module layer to generate an additional clamping force on the cable.

[0007] By adopting the above technical solution, the main enclosure is divided into three functionally independent chambers—an equipment chamber, a control chamber, and a cable chamber—by vertical partitions. Each chamber has an independent door with a sealing strip, ensuring that each chamber can be opened independently during routine maintenance without compromising the sealing of other chambers. All cables entering and exiting the ring main unit enter a centralized cable sealing transfer box through the inlet hole on the bottom plate of the cable chamber. From there, the transfer box distributes the cables to the respective chambers. The bottom plates of the equipment chamber and control chamber are complete panels without any cable inlet holes, eliminating the risk of moisture intruding into the main enclosure through multiple dispersed cable holes at the structural source. This concentrates the cable sealing function entirely within a single controllable module in the cable chamber. The transfer box contains a three-layer progressive sealing system: a sealing module layer, an expansion sealing layer, and a fire-resistant sheath layer, arranged from top to bottom. These layers respectively provide mechanical foundation sealing, water-adaptive enhanced sealing, and fireproof barrier functions. The drainage tank and its internal level sensor and drainage pump constitute an active drainage system, ensuring timely removal of any seepage or accumulated water. Specifically, the mounting plate and liquid level clamping module located between the sealing module layer and the expansion sealing layer utilize the mechanical energy of the expansion sealing layer expanding in volume when it comes into contact with water. Through a lever mechanism, the sealing module layer is directly driven to generate an additional radial clamping force, realizing a purely mechanical "the deeper the water, the tighter the seal" adaptive linkage response. It can complete the sealing enhancement action without relying on external power supply or sensor signals, greatly improving the protection reliability and response time of the ring main unit in water-filled environments.

[0008] Optionally, the lever mechanism includes a fulcrum and a lever plate rotatably connected to the fulcrum. One end of the lever plate is connected to the drive member, and the other end is integrally formed with a drive plate. The drive plate abuts against the lower part of the sealing module layer. A transmission rod is hinged to the end of the lever plate near the drive member. The transmission rod passes through the fulcrum and extends into the connecting hole. A pressing plate is formed at the end of the transmission rod. The pressing plate abuts against the upper part of the expansion sealing layer.

[0009] By adopting the above technical solution, when the expansion sealing layer expands upon contact with water and is extruded upwards, it directly pushes the transmission rod and its end extrusion plate, which extend into the connecting hole. The transmission rod drives the lever plate to swing around the fulcrum seat, and the drive plate at the other end of the lever plate simultaneously pushes upwards against the lower part of the sealing module layer, thereby accurately converting the expansion displacement of the expansion sealing layer into a pressing stroke on the sealing module layer. This purely mechanical lever transmission structure requires no electrical components, has a direct response, reliable operation, and the lever ratio can be designed as needed to amplify the pressing effect.

[0010] Optionally, the driving component is an SMA drive spring, and the liquid level clamping module also includes a PTC heating element and a return spring; one end of the SMA drive spring is connected to the fulcrum seat, and the other end is connected to the lever plate; the PTC heating element is installed on the fulcrum seat and electrically connected to the drain controller, and the drain controller is connected to the liquid level sensor signal; the return spring is sleeved on the transmission rod, with one end connected to the fulcrum seat and the other end connected to the lever plate.

[0011] By adopting the above technical solution, after the liquid level sensor detects the water accumulation signal, it triggers the PTC heating element to be energized and heated through the drainage controller. The SMA drive spring undergoes a phase change and elongates upon heating, assisting the lever mechanism in its action. This, combined with the mechanical thrust of the expansion sealing layer itself, forms a dual drive, further enhancing the reliability of the clamping response and the clamping force. Simultaneously, after the water accumulation is drained and the PTC is de-energized, the return spring pushes the lever mechanism to reset, restoring the sealing module layer to its normal clamping force and preventing long-term excessive clamping from damaging the cable insulation.

[0012] Optionally, the drive plate is arc-shaped, with its curvature matching the outer peripheral surface of the sealing module layer; the extrusion plate is arc-shaped, with its curvature matching the outer peripheral surface of the cable.

[0013] By adopting the above technical solution, the outer peripheral surfaces of the drive board and the sealing module layer, and the outer peripheral surfaces of the extrusion plate and the cable are all designed with arc-shaped curved surfaces, which increases the contact area, makes the clamping force evenly distributed, avoids local stress concentration that could damage the sealing module or the cable insulation layer, and improves the force transmission efficiency.

[0014] Optionally, the sealing module layer consists of multiple independent silicone rubber sealing modules. Each sealing module is formed by two semi-circular ring modules interlocking. The mating surfaces of the two semi-circular ring modules are respectively provided with ribs and grooves. A clamping flange is provided above the sealing module layer. The clamping flange has circular through holes corresponding to the positions of each sealing module. Each circular through hole forms a clamping arc surface on the side facing the sealing module. The clamping arc surface is continuous and annular. The clamping flange is connected to a fixed seat fixed to the inner wall of the adapter box by adjusting bolts.

[0015] By adopting the above technical solution, the two semi-circular silicone rubber modules are interlocked, and the interlocking of the ribs and grooves ensures a reliable seal at the joint surface. The clamping flange applies axial compression force through adjusting bolts, and the clamping arc surface guides the sealing module to expand radially evenly, generating a stable basic radial clamping force on the cable passing through it. This structure is easy to install, and the sealing pressure is adjustable to meet the sealing requirements of cables with different outer diameters.

[0016] Optionally, the expansion sealing layer is made of water-swellable sealing putty, with a support grid embedded in the middle of the putty layer. Multiple cable separation brackets are fixed on the support grid, and each separation bracket has a semi-circular slot for the cable to be inserted.

[0017] By adopting the above technical solution, the water-swellable sealant expands significantly in volume upon contact with water, adaptively filling the gap between the cable and the inner wall of the junction box, thus achieving enhanced sealing driven by water pressure. The support grid prevents the sealant from being lost due to gravity during long-term use, and the cable separator ensures even distribution among multiple cables, avoiding cable aggregation that could lead to uneven sealing.

[0018] Optionally, the fire-resistant cladding is composed of multiple stacked fireproof bags, and a perforated pressure plate is provided below the fire-resistant cladding. The perforated pressure plate is suspended from the inner surface of the lower wall panel of the adapter box by adjusting screws.

[0019] By adopting the above technical solution, the fireproof bag expands upon contact with fire to form a dense carbonized layer, effectively blocking the spread of flames along the cable channel and achieving fireproof partitioning at the cable penetration point. The porous pressure plate applies pre-pressure to the fireproof bag layer through adjusting the screw, ensuring that the fireproof bag is filled tightly, while the porous structure does not affect drainage and cable installation.

[0020] Optionally, the drainage box is fixed to the bottom surface of the transfer box by welding. A cable guide is installed in the cable hole of the drainage box, and the outer wall of the cable guide abuts against the inner wall of the cable hole. One end of the cable guide is fixed to the bottom wall of the drainage box, and the other end is fixed to the bottom plate of the cable compartment. Multiple cable inlet and outlet holes are opened in the cable guide for cables to pass through. Sealing gaskets are provided between the cable guide and the drainage box, and between the cable guide and the bottom plate of the cable compartment.

[0021] By adopting the above technical solution, the drainage box is independently welded to the bottom surface of the junction box, spatially separating the drainage function from the sealing function of the junction box body. The cable conduit provides a dedicated channel for cables to enter the drainage box from the outside and then enter the junction box. Both ends of the cable conduit are sealed to the bottom plate of the drainage box and the cable compartment, respectively. The double sealing gaskets effectively prevent water or moisture accumulated in the drainage box from seeping back into the junction box or cable compartment along the cable channel, ensuring the independent sealing of the drainage path and the cable channel.

[0022] Optionally, the top of the junction box is equipped with a humidity isolation structure, which includes an insulating partition and a flexible cable through-hole sealing ring. The insulating partition is horizontally fixed to the top surface of the junction box and has through holes that correspond one-to-one with the cable outlets on the top of the junction box. Each through hole is inlaid with a flexible cable through-hole sealing ring. Each cable is fitted with an adjusting bushing, and each adjusting bushing is threaded with a sealing ring pressure ring. The sealing ring pressure ring can be axially displaced along the adjusting bushing to axially press the sealing ring.

[0023] By adopting the above technical solution, the insulating partition and the flexible cable through-hole sealing ring establish a physical airtight isolation barrier between the top of the transfer box and the cable compartment, preventing residual moisture inside the transfer box from rising into the cable compartment and equipment compartment. The sealing ring pressure ring is tightened by adjusting the axial displacement of the thread, so that the inner lip of the sealing ring is tightly against the cable surface and the outer lip is tightly against the through-hole wall. The sealing pressure is adjustable to adapt to different cable operating conditions.

[0024] Optionally, the main enclosure has a drain outlet on the bottom plate of the cable compartment, and a drain connector is installed inside the drain outlet. The drain connector is welded to the inner wall of the cable compartment via a flange ring. The inlet end of the drain connector is connected to the drain pipe, and the outlet end of the drain connector is connected to the external drainage pipe.

[0025] By adopting the above technical solution, the drain pipe end is connected to the external drain pipe through a drain joint fixed by flange welding. The structure is solid and the seal is reliable, preventing leakage at the drain interface due to vibration or temperature difference, and ensuring that the accumulated water is smoothly discharged outside the box.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. By dividing the main enclosure into an equipment room, a control room, and a cable room, and concentrating all cables into an independent junction box in the cable room, the cable entry holes on the floor of the equipment room and control room are eliminated. This fundamentally blocks the path of moisture entering the main enclosure through multiple dispersed cable holes, significantly improving the overall protection level and anti-condensation capability of the ring main enclosure.

[0027] 2. The junction box is equipped with a three-layer progressive sealing structure consisting of a sealing module layer, an expansion sealing layer, and a fire-resistant envelope layer. These layers respectively provide mechanical sealing, water-adaptive enhanced sealing, and fireproof barrier functions, forming a multi-level protective barrier to cope with different threat scenarios.

[0028] 3. By setting an installation plate and a purely mechanical lever-type liquid level clamping module between the sealing module layer and the expansion sealing layer, the mechanical energy of the expansion sealing layer expanding when it encounters water directly drives the sealing module layer to generate an additional radial clamping force, realizing a positive feedback adaptive linkage response of "the deeper the water accumulation, the tighter the seal". It does not rely on external power supply or sensor signals, and the response is direct and highly reliable.

[0029] 4. The drainage box is independently welded to the bottom surface of the junction box and is connected to the junction box and cable compartment through a double sealing structure of the cable tube. This spatially decouples the drainage function from the cable sealing function, ensuring that the accumulated water is discharged smoothly and preventing moisture in the drainage box from seeping back along the cable channel.

[0030] 5. The overall structure decouples daily operation and maintenance from sealing protection—maintenance personnel can independently open the doors of each chamber for operation, the centralized junction box in the cable room maintains a stable and sealed state, and the sealing integrity of the equipment room and control room is not affected by maintenance operations, thus balancing high protection performance and ease of operation and maintenance. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 yes Figure 1 A magnified view of part A in the middle; Figure 3 This is a structural diagram of the present application, mainly showing the threading tube; Figure 4 This is a structural schematic diagram of the present application, mainly showing the sealing module; Figure 5 This is a structural schematic diagram of the present application, mainly showing the clamping flange; Figure 6 This is a structural schematic diagram of the present application, mainly showing the expansion sealing layer; Figure 7 This is a structural diagram of the present application, mainly showing the liquid level clamping module.

[0032] Explanation of reference numerals in the attached drawings: 1. Main housing; 2. Adapter box; 3. Sealing module; 4. Expansion sealing layer; 41. Adhesive; 42. Support grid; 43. Divider bracket; 5. Fire-retardant cladding; 6. Active drainage system; 61. Drainage tank; 62. Liquid level sensor; 63. Miniature drainage pump; 64. Check valve; 7. Humidity isolation structure; 71. Insulating partition; 72. Sealing ring; 73. Pressure ring; 74. Adjusting bushing; 75. Humidity sensor; 76. Humidity indicator light; 8. Liquid level clamping module; 81. SMA drive spring; 82. PTC heating element; 83. Return spring; 84. Pivot seat; 85. Lever plate; 86. Transmission rod; 87. Drive plate; 88. Extrusion plate; 9. Sealing strip; 10. Drain connector; 11. Clamping flange; 111. Clamping arc surface; 12. Fixing seat; 13. Tighten adjusting bolt; 14. Multi-hole pressure plate; 15. Rotary adjusting screw; 16. Cable guide tube; 17. Sealing gasket; 18. Mounting plate. Detailed Implementation

[0033] The following is in conjunction with the appendix Figure 1 - Appendix Figure 7 This application will be described in further detail below.

[0034] A fully sealed outdoor ring main unit with a centralized cable sealing junction box includes a main body 1, within which a centralized cable sealing junction box 2 is installed, and all cables entering and exiting the ring main unit pass through this junction box 2. The junction box 2 integrates a sealing module layer, an expansion sealing layer 4, and a fire-retardant sheath 5 arranged sequentially from top to bottom, forming a three-layer sealing structure. Additionally, the main body 1 also includes an active drainage system 6, a humidity isolation structure 7, and a liquid level clamping module 8.

[0035] refer to Figure 1 , Figure 2 The main enclosure 1 is divided into an equipment room, a control room, and a cable room by partitions. Each of these rooms is connected to a door via hinges. A sealing strip 9 is provided on the inner edge of each door; when the door is closed, this sealing strip 9 is pressed into the sealing strip 9 mounting groove of the door frame, creating an airtight seal. The bottom plate of the cable room has an inlet hole for cable routing. A junction box 2 is installed inside the cable room, and the cable extends into the junction box 2 through the inlet hole. A drain outlet is provided in the bottom plate of the cable room, and a drain connector 10 is installed inside the drain outlet. The drain connector 10 is welded to the inner wall of the cable room via a flange ring. The inlet end of the drain connector 10 is connected to the drain pipe of the active drainage system 6 via a one-way valve 64, and the outlet end of the drain connector 10 is connected to an external drainage pipe.

[0036] refer to Figure 1 , Figure 3The centralized cable sealing junction box 2 is installed in the cable compartment of the main enclosure 1. The junction box 2 is fixedly installed inside the main enclosure 1, with the cable entry holes corresponding to the cable outlet holes inside. Inside the junction box 2, from top to bottom vertically, a sealing module layer, an expansion sealing layer 4, and a fire-retardant sheath layer 5 are arranged sequentially, forming a three-layer sealing structure. The sealing module layer is located at the top of the junction box 2, adjacent to the lower surface of the top of the junction box 2. This module layer consists of multiple independent silicone rubber sealing modules 3, with one silicone rubber sealing module 3 corresponding to each cable outlet.

[0037] refer to Figure 3 , Figure 4 Each sealing module 3 consists of two interlocking semi-circular silicone rubber modules. The mating surfaces of the two semi-circular modules are respectively provided with ribs and grooves; after interlocking, the ribs embed into the grooves to form an interlock. The outer circumferential surface of the sealing module 3 is cylindrical, leaving a gap between it and the inner wall of the adapter box 2. The inner circumferential surface is an arc surface matching the outer diameter of the cable. The sealing module 3 is made of self-adhesive silicone rubber material, possessing good elastic deformation capability and self-adhesive properties.

[0038] refer to Figure 4 , Figure 5 A stainless steel clamping flange 11 is provided above the silicone rubber sealing module layer. The clamping flange 11 is rectangular and has circular through holes corresponding to the positions of each sealing module 3. The inner wall of each circular through hole facing the sealing module 3 forms a clamping arc surface 111, which is continuous and annular. The four corners of the clamping flange 11 are connected to the fixing seats 12 pre-welded to the four corners of the inner wall of the adapter box 2 by adjusting bolts. Tightening the adjusting bolts 13 can move the clamping flange 11 downward, which generates axial compression on the sealing module 3 below as it slides along the clamping arc surface 111. At the same time, the sealing module 3 generates radial expansion under the axial compression, thereby generating a radial clamping force on the cable passing through its inner hole, achieving a seal.

[0039] refer to Figure 4 , Figure 6 The expansion sealing layer 4 is located below the sealing module layer, with a gap between them. This putty layer 41 is composed of water-swellable sealing putty 41, which is based on polyurethane and contains uniformly dispersed superabsorbent polymer particles. The putty 41 is in a plastic and malleable state at room temperature and can be manually molded and filled in the middle area of ​​the inner cavity of the adapter box 2, with the filling thickness covering the middle section of the height direction of the adapter box 2.

[0040] A PP support grid 42 is embedded in the middle of the putty layer 41. This support grid 42 is flat and covered with square mesh holes with sides approximately 10 mm in diameter. A gap is left between the perimeter of the support grid 42 and the inner wall of the adapter box 2 to prevent the putty 41 from leaking or deforming due to gravity during long-term use. Multiple nylon cable divider brackets 43 are fixed to the support grid 42. These brackets are spaced apart, and each bracket has a semi-circular slot. Cables are inserted into their corresponding slots to maintain a uniform spacing between cables.

[0041] refer to Figure 3 The fire-resistant sheath 5 is located below the expansion sealing layer 4 and above the cable inlet on the lower wall panel of the junction box 2. This filling layer is composed of multiple stacked PFB-type fireproof bags. Each fireproof bag is square and filled with an intumescent flame retardant, which expands to form a dense carbonized layer when exposed to fire. The fireproof bags are stacked one by one around the cables, filling to the designed thickness to form a fire barrier surrounding each cable. Below the fire-resistant sheath 5 is a stainless steel perforated pressure plate 14. The perforated pressure plate 14 is rectangular and has multiple large circular holes for cables to pass through and multiple small holes for water supply and drainage. The four corners of the perforated pressure plate 14 are suspended from the inner surface of the lower wall panel of the junction box 2 by adjusting screws. Rotating the adjusting screws 15 can adjust the tightness of the perforated pressure plate 14, so that it applies a certain pressure to the fire-resistant sheath 5.

[0042] The active drainage system 6 includes a drainage box 61 located at the bottom of the adapter box 2. The drainage box 61 is welded to the bottom surface of the adapter box 2 and communicates with the interior of the adapter box 2 through a cable passage hole. A cable pass-through tube 16 is installed in the cable passage hole of the drainage box 61, with the outer wall of the cable pass-through tube 16 abutting against the inner wall of the cable passage hole. One end of the cable pass-through tube 16 is fixed to the inner bottom wall of the drainage box 61 with screws, and the other end of the cable pass-through tube 16 is fixed to the bottom plate of the main box 1 with screws. The cable pass-through tube 16 has multiple circular cable inlet and outlet holes for cables to pass through. Cables can extend from the outside into the drainage box 61 and then into the adapter box 2 through these cable inlet and outlet holes. Sealing gaskets 17 are provided between the cable pass-through tube 16 and the drainage box 61, and between the cable pass-through tube 16 and the cable compartment.

[0043] refer to Figure 2 , Figure 3 The drainage tank 61 is equipped with a liquid level sensor 62, a miniature drainage pump 63, a drainage pipe, and a one-way valve 64. The miniature drainage pump 63 is fixed to the outer wall of one side of the drainage tank 61. Its inlet is connected to a flexible hose that extends into the drainage tank 61, and its outlet is connected to the inlet of the one-way valve 64 via a pipe. The outlet of the one-way valve 64 is connected to the drainage pipe, and the outlet of the drainage pipe is connected to the inlet of the drainage connector 10. The one-way valve 64 is opened in the direction of outward water flow to prevent external water from flowing back into the drainage tank 61.

[0044] refer to Figure 4 A humidity-isolation structure 7 is located on the top of the adapter box 2 and comprises an insulating partition 71, multiple elastic cable through-hole sealing rings 72, and sealing ring pressure rings 73. The insulating partition 71 is a rectangular flat plate made of glass fiber reinforced plastic, placed horizontally on the top surface of the adapter box 2. Its perimeter is fixed to the top surface of the adapter box 2 by screws. The insulating partition 71 has circular through-holes corresponding to the cable outlets on the top of the adapter box 2. Each through-hole contains an elastic cable through-hole sealing ring 72 with a lip-shaped cross-section, having an inner lip and an outer lip. The inner lip is tightly fitted against the outer circumference of the cable passing through it, and the outer lip is tightly fitted against the hole wall of the insulating partition 71. Each cable is fitted with an adjusting bushing 74, and each adjusting bushing 74 is threadedly connected to a sealing ring 72 pressure ring 73. The pressure ring 73 can move axially along the adjusting bushing 74, thereby axially pressing the sealing ring 72.

[0045] refer to Figure 2 , Figure 4 A humidity sensor 75 is fixedly installed on the surface of the insulating partition 71 to monitor the humidity inside the cable compartment. Furthermore, a three-color humidity indicator light 76 is installed on the outer wall panel of the cable compartment door, electrically connected to the humidity sensor 75, and displays green, yellow, or red respectively according to the humidity value.

[0046] refer to Figure 4 , Figure 7 The liquid level clamping module 8 comprises an SMA drive spring 81, a PTC heating element 82, a lever amplification structure, and a return spring 83. The lever amplification structure includes a fulcrum 84 and a lever plate 85 rotatably connected to the fulcrum 84. One end of the lever plate 85 is connected to the SMA drive spring 81, and the other end is connected to the return spring 83. A support rod passes through the portion of the lever plate 85 near the SMA drive spring 81, and both ends of the support rod are rotatably connected to the fulcrum 84. The end of the SMA drive spring 81 facing away from the lever plate 85 is connected to the fulcrum 84, and the end of the return spring 83 facing away from the lever plate 85 is connected to the fulcrum 84. Furthermore, the PTC heating element 82 is installed on the side of the fulcrum 84 opposite to the SMA drive spring 81, and the PTC heating element 82 is electrically connected to a drain controller, which is signal-connected to the liquid level sensor 62.

[0047] An installation plate 18 is welded and fixed inside the adapter box 2 between the sealing module layer and the expansion sealing layer 4. The installation plate 18 has a connecting hole for the cable to pass through. The expansion sealing layer 4 can be squeezed out through the connecting hole after it expands when exposed to water. Three liquid level clamping modules 8 are installed along the edge of each connecting hole of the installation plate 18. A drive plate 87 is integrally formed on one end of the lever plate 85 and the return spring 83, and the drive plate 87 abuts against the bottom of the sealing module layer. The drive plate 87 is arc-shaped, and its curvature matches that of the sealing module 3.

[0048] A transmission rod 86 is hinged to one end of the lever plate 85 and the return spring 83. The transmission rod 86 passes through the fulcrum seat 84 and extends into the connecting hole, and the return spring 83 is sleeved on the outside of the transmission rod 86. An extrusion plate 88 is integrally formed at the end of the transmission rod 86. The extrusion plate 88 abuts against the top of the expansion sealing layer 4, and the extrusion plate 88 is arc-shaped with a curvature that matches the outer periphery of the cable.

[0049] The implementation principle of this application embodiment is as follows: The main enclosure 1 is divided into three independent chambers—an equipment chamber, a control chamber, and a cable chamber—by vertical partitions. Each chamber has an independent door and is sealed with a sealing strip 9 to form an airtight seal. All cables entering and exiting the ring main unit enter the centralized cable sealing transfer box 2 through the inlet hole in the bottom plate of the cable chamber, and then exit from the transfer box 2 to each chamber. The bottom plates of the equipment chamber and the control chamber are both complete panels without cable inlet holes, eliminating the potential for moisture to diffuse and intrude through multiple cable holes from the structural source, and concentrating the cable sealing function entirely in the transfer box 2 inside the cable chamber.

[0050] Inside the junction box 2, from top to bottom vertically, are arranged a sealing module layer, an expansion sealing layer 4, and a fire-resistant sheath 5. The sealing module layer consists of two interlocking semi-circular silicone rubber modules. The axial compression of the clamping flange 11 generates radial clamping force, achieving a basic mechanical seal on the cable surface. The expansion sealing layer 4 is filled with water-swellable sealing putty 41. Upon contact with water, the superabsorbent polymer in the putty 41 absorbs water and expands, increasing in volume and squeezing the cable radially inward and the inner wall of the junction box 2 outward, achieving an adaptive enhanced seal. The fire-resistant sheath 5 is composed of stacked fireproof bags. When exposed to fire, it expands to form a dense carbonized layer, blocking the flame propagation path.

[0051] A separate drainage tank 61 is welded to the bottom of the adapter box 2. The drainage tank 61 is equipped with a liquid level sensor 62 and a drainage pump. When water accumulates in the cable trench and flows up the cable into the drainage tank 61, the liquid level sensor 62 detects that the water level has reached a preset threshold, triggering the drainage pump to start. The water is then discharged to the outside of the main box 1 through the drainage pipe and the one-way valve 64. The end of the drainage pipe is connected to the external drainage pipe through the drainage connector 10. The one-way valve 64 ensures that the water flows out only to the outside, preventing backflow of external water.

[0052] An installation plate 18 is provided inside the adapter box 2 between the sealing module layer and the expansion sealing layer 4, and the installation plate 18 has a connecting hole. After the expansion sealing layer 4 expands when it comes into contact with water, the putty 41 is squeezed upward from the connecting hole, pushing the extrusion plate 88 at the end of the transmission rod 86, which extends into the connecting hole, to move upward. The transmission rod 86 drives the lever plate 85 to swing around the fulcrum seat 84, and the drive plate 87 at the other end of the lever plate 85 pushes the clamping flange 11 of the sealing module layer upward, so that the sealing module 3 generates additional axial compression and radial clamping force, further enhancing the seal on the cable. At the same time, the liquid level sensor 62 signals to trigger the drain controller to supply power to the PTC heating element 82. The PTC heating element 82 heats the SMA drive spring 81 to generate a restoring force, which assists in driving the lever mechanism. The expansion energy of the expansion sealing layer 4 and the restoring force of the SMA drive spring 81 form a dual drive, realizing a positive feedback adaptive seal where the deeper the water accumulation, the tighter the seal.

[0053] The drainage box 61 is connected to the interior of the transfer box 2 and the bottom plate of the cable compartment via a cable conduit 16. Cable entry and exit holes are provided inside the cable conduit 16, through which cables enter the drainage box 61 from the outside and then enter the transfer box 2. Sealing gaskets 17 are installed between the cable conduit 16 and the drainage box 61, and between the cable conduit 16 and the bottom plate of the cable compartment, forming a double-sealed isolation structure. This spatially decouples the drainage function from the cable sealing function, ensuring unobstructed drainage while preventing water or moisture accumulated in the drainage box 61 from seeping back into the transfer box 2 or the cable compartment along the cable channel.

[0054] The top of the junction box 2 is equipped with an insulating partition 71, on which through holes corresponding to the cable outlets are opened. Each through hole is fitted with an elastic cable through hole sealing ring 72. Each cable is fitted with an adjusting bushing 74 and a sealing ring pressure ring 73. The sealing ring pressure ring 73 can be axially pressed along the adjusting bushing 74 to form a physical airtight isolation barrier between the junction box 2 and the cable compartment, preventing residual moisture from entering the cable compartment and equipment compartment.

[0055] The aforementioned functional modules form a complete collaborative protection system: the cable compartment centrally handles the sealing of all cables, while the zero cable holes in the bottom plates of the remaining chambers ensure the structural integrity of the main enclosure 1; the three-layer layered sealing provides multi-level protective barriers; the active drainage system 6 promptly drains any seeping water; the mechanically linked liquid level clamping module 8 utilizes the expansion energy of the expansion sealing layer 4 to enhance the seal, requiring no continuous power supply; and the humidity isolation structure 7 serves as the final barrier to block residual moisture. These functional modules work together and complement each other, achieving comprehensive, multi-level protection against moisture inrush from the cable trench.

[0056] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fully sealed outdoor ring main unit with a centralized cable sealing junction box, comprising a main box (1), characterized in that: The main enclosure (1) is divided into an equipment room, a control room and a cable room by vertical partitions. The equipment room, control room and cable room are all equipped with openable doors. Each door has a sealing strip (9) on its inner edge to form an airtight seal. The cable room is equipped with a centralized cable sealing junction box (2). The bottom plate of the cable room has an inlet hole for cable passage. Cables entering and exiting the ring network box enter the junction box (2) through the inlet hole and then pass out of the junction box (2) into the main box (1). The bottom plates of the equipment room and the control room are both complete plates without cable inlet holes. The adapter box (2) is arranged vertically from top to bottom with a sealing module layer, an expansion sealing layer (4) and a fire-resistant layer (5), forming a three-layer sealing structure; The bottom of the adapter box (2) is provided with a drain box (61). The drain box (61) is provided with a liquid level sensor (62) and a drain pump. The outlet of the drain pump is connected to a drain pipe through a one-way valve (64). The drain pipe extends to the outside of the main box (1). The adapter box (2) has an installation plate (18) between the sealing module layer and the expansion sealing layer (4). The installation plate (18) has a through hole for the cable to pass through. A liquid level clamping module (8) is installed on the installation plate (18). The liquid level clamping module (8) includes a driving component and a lever mechanism. One end of the lever mechanism is connected to the driving component, and the other end abuts against the sealing module layer. After the expansion sealing layer (4) expands when it comes into contact with water, it is squeezed out from the through hole and pushes the lever mechanism to move, so as to drive the sealing module layer to generate an additional clamping force on the cable.

2. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 1, characterized in that, The lever mechanism includes a fulcrum (84) and a lever plate (85) rotatably connected to the fulcrum (84). One end of the lever plate (85) is connected to the driving member, and the other end is integrally formed with a driving plate (87). The driving plate (87) abuts against the lower part of the sealing module layer. A transmission rod (86) is hinged to one end of the lever plate (85) near the driving member. The transmission rod (86) passes through the fulcrum (84) and extends into the communicating hole. A pressing plate (88) is formed at the end of the transmission rod (86). The pressing plate (88) abuts against the upper part of the expansion sealing layer (4).

3. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 2, characterized in that, The driving component is an SMA driving spring (81), and the liquid level clamping module (8) also includes a PTC heating element (82) and a return spring (83); one end of the SMA driving spring (81) is connected to the fulcrum seat (84), and the other end is connected to the lever plate (85); the PTC heating element (82) is installed on the fulcrum seat (84) and electrically connected to the drainage controller, and the drainage controller is signal connected to the liquid level sensor (62); the return spring (83) is sleeved on the transmission rod (86), one end of which is connected to the fulcrum seat (84), and the other end is connected to the lever plate (85).

4. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 3, characterized in that, The drive plate (87) is arc-shaped, and its curvature matches the outer peripheral surface of the sealing module layer; the extrusion plate (88) is arc-shaped, and its curvature matches the outer peripheral surface of the cable.

5. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 1, characterized in that, The sealing module layer is composed of multiple independent silicone rubber sealing modules (3). Each sealing module (3) is formed by two semi-circular ring modules interlocking together. The two semi-circular ring modules are respectively provided with ribs and grooves on their respective mating surfaces. A clamping flange (11) is provided above the sealing module layer. The clamping flange (11) is provided with circular through holes corresponding to the positions of each sealing module (3). Each circular through hole forms a clamping arc surface (111) on the side facing the sealing module (3). The clamping arc surface (111) is a continuous ring. The clamping flange (11) is connected to the fixing seat (12) fixed to the inner wall of the adapter box (2) by adjusting bolts.

6. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 1, characterized in that, The expansion sealing layer (4) is filled with water-swellable sealing putty (41). A support grid (42) is embedded in the middle of the putty (41) layer. Multiple cable separation brackets (43) are fixed on the support grid (42). Each separation bracket (43) has a semi-circular slot for the cable to be inserted.

7. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 1, characterized in that, The fire-resistant layer (5) is composed of multiple fireproof bags stacked and filled. A perforated pressure plate (14) is provided below the fire-resistant layer (5). The perforated pressure plate (14) is suspended on the inner surface of the lower wall of the adapter box (2) by an adjusting screw.

8. The fully sealed outdoor ring main unit with centralized cable sealing junction box as described in claim 1, characterized in that, The drainage box (61) is fixed to the bottom surface of the adapter box (2) by welding. A wire threading tube (16) is installed in the wire threading hole of the drainage box (61). The outer wall of the wire threading tube (16) abuts against the inner wall of the wire threading hole. One end of the wire threading tube (16) is fixed to the inner bottom wall of the drainage box (61), and the other end is fixed to the bottom plate of the cable chamber. Multiple cable inlet and outlet holes for cables to pass through are opened in the wire threading tube (16). Sealing gaskets (17) are provided between the wire threading tube (16) and the drainage box (61), and between the wire threading tube (16) and the bottom plate of the cable chamber.

9. The fully sealed outdoor ring main unit with centralized cable sealing junction box according to claim 1, characterized in that, The top of the adapter box (2) is provided with a humidity isolation structure (7). The humidity isolation structure (7) includes an insulating partition (71) and an elastic cable through hole sealing ring (72). The insulating partition (71) is horizontally fixed to the top surface of the adapter box (2). It has through holes that correspond one-to-one with the cable outlets at the top of the adapter box (2). The elastic cable through hole sealing ring (72) is embedded in each through hole. Each cable is fitted with an adjusting bushing (74). Each adjusting bushing (74) is externally threaded with a pressure ring (73). The pressure ring (73) can be axially displaced along the adjusting bushing (74) to axially press the sealing ring (72).

10. The fully sealed outdoor ring main unit with centralized cable sealing junction box according to claim 1, characterized in that, The main housing (1) has a drain outlet on the bottom plate of the cable compartment. A drain connector (10) is installed in the drain outlet. The drain connector (10) is welded and fixed to the inner wall of the cable compartment by a flange ring. The inlet end of the drain connector (10) is connected to the drain pipe, and the outlet end of the drain connector (10) is connected to the external drainage pipe.

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