A hierarchical pressure relief low voltage switchgear

Abstract

The application relates to the technical field of low-voltage switch cabinet safety protection, and discloses a hierarchical pressure relief low-voltage switch cabinet which comprises a cabinet body, a feeder cabinet, an air duct, a pressure relief box body arranged at the top of the cabinet body and communicated with the feeder cabinet, a first-level pressure relief assembly arranged in the middle of the pressure relief box body, and second-level pressure relief assemblies arranged at both sides of the pressure relief box body. The first-level pressure relief assembly comprises an electric magnet, a magnetic block, a top plate, a connecting rod and a sensor, and is used for quickly opening the middle pressure relief channel in the initial stage of failure; the second-level pressure relief assembly comprises a pressure relief window, a torsional spring and a mechanical limiting assembly, and is used for opening the two-side pressure relief channels to expand the pressure relief area when the failure is aggravated. The switch cabinet can implement hierarchical pressure relief according to the severity of the failure, and the response speed, the reliability and the use safety of the pressure relief are improved.

Description

Technical Field

[0001] This invention relates to the field of safety protection technology for low-voltage switchgear, and in particular to a low-voltage switchgear with a tiered pressure relief system. Background Technology

[0002] Low-voltage switchgear is a key piece of equipment in power systems used for power distribution and energy conversion. It contains electrical components such as circuit breakers, disconnectors, and instrument transformers, and typically operates at 220V single-phase and 380V three-phase AC voltage levels. In typical low-voltage application scenarios such as industrial plant power distribution rooms, commercial building main power distribution rooms, residential substations, and data centers, low-voltage switchgear plays a crucial role in providing control and protection for end loads such as motors, lighting, air conditioning, and UPS systems. The load current can reach hundreds or even thousands of amperes, and it operates under continuous load for extended periods.

[0003] Because the components inside the cabinet operate in a high-current environment for extended periods, short circuits may occur due to various reasons, including insulation aging (accelerated degradation in damp underground distribution rooms or high-temperature factories), poor busbar contact (loosening of bolts due to vibration or thermal expansion and contraction), foreign object intrusion (such as rodent gnawing or dust accumulation causing creepage), or operational errors. The inrush current during motor startup can also exacerbate contact wear and increase the probability of arcing. If the high-temperature, high-pressure gas generated by the short-circuit arc cannot be discharged in time, it will cause a rapid increase in pressure inside the cabinet, potentially leading to cabinet explosions, fires, and other serious accidents, threatening the personal safety of maintenance personnel and the operational safety of surrounding electrical equipment.

[0004] To address the aforementioned risks, existing low-voltage switchgear typically incorporates pressure relief channels at the top or rear of the cabinet to release high-temperature, high-pressure gases. However, existing pressure relief structures often employ a single method, which has particularly pronounced drawbacks in low-voltage scenarios: when the fault arc energy is relatively small (e.g., single-phase grounding arc or auxiliary circuit short circuit), the discharge flow is excessive when the pressure relief port is fully open, causing secondary damage to environmentally sensitive locations such as data centers and cleanrooms due to airflow impact and dust diffusion; when the fault arc energy is relatively large (e.g., a three-phase short circuit on a 380V busbar), the short-circuit current in the low-voltage system can reach tens of kiloamperes, and the discharge capacity of a single pressure relief port is insufficient, preventing the pressure inside the cabinet from dropping below the threshold within a safe time, posing significant safety hazards in densely populated commercial buildings or industrial control rooms. Furthermore, the response speed of purely mechanical triggering mechanisms is limited by inertia, making it difficult to handle low-voltage arcs lasting only tens of milliseconds; while electrical signal triggering devices have a faster response, they lack graded pressure relief capabilities and cannot adaptively adjust the pressure relief amount according to the severity of the fault, resulting in a lack of reasonable matching between the pressure relief effect and the fault level.

[0005] In summary, there is an urgent need to design a low-voltage switchgear pressure relief structure that can achieve layered and staged pressure relief based on the degree of fault within the cabinet, so that it can adaptively relieve pressure according to the severity of the fault, in order to meet the safety requirements of various low-voltage power distribution scenarios such as industrial, commercial, and civil use. Summary of the Invention

[0006] This invention provides a tiered pressure relief low-voltage switchgear to solve the technical problem that the existing low-voltage switchgear pressure relief structure adopts a single pressure relief method, which cannot perform tiered adaptive pressure relief according to the severity of the fault in the cabinet, resulting in excessive pressure relief when the fault energy is small and insufficient pressure relief when the fault energy is large.

[0007] This invention adopts the following technical solution: a low-voltage switchgear with hierarchical pressure relief, comprising a cabinet, wherein interconnected power supply cabinets and air ducts are arranged inside the cabinet, and electronic components are installed inside the power supply cabinets. The top of the cabinet is equipped with a pressure relief box that is connected to the power supply cabinet. When a short circuit fault occurs in the electronic components, the pressure relief box will automatically open to achieve layered pressure relief inside the cabinet. The pressure relief box is equipped with a first-level pressure relief component in the middle, which is used to respond to circuit faults inside the cabinet to perform first-level pressure relief; the pressure relief box is equipped with second-level pressure relief components on both sides, which are used to respond to circuit fault signals inside the cabinet to perform second-level pressure relief.

[0008] Furthermore, the pressure relief box includes a support cover fixedly installed on the upper part of the cabinet. The support cover is in the shape of an inverted U. A retaining plate is provided at the end of the support cover. The end of the retaining plate is provided with a hook. A slot is provided on the side of the support cover. The hook is adapted to engage in the slot to fix the retaining plate and the support cover together.

[0009] Furthermore, the first-level pressure relief assembly includes a support frame fixedly installed at both ends of the support cover, a magnet fixedly installed in the middle of the support frame, and limit grooves opened at both ends; a top plate is provided on the upper end of the support frame, and connecting rods are hinged around the lower end surface of the top plate, with the other end of the connecting rods movably connected in the limit groove.

[0010] Furthermore, the top plate has a magnetic block on its side that fits and is compatible with the magnet; the lower end of the support frame has a sensor that can receive smoke signals from inside the cabinet and trigger the magnet to be energized, causing the magnetic block to detach from the magnet, thereby popping the top plate open.

[0011] Furthermore, the second-level pressure relief assembly includes a pressure relief window hinged to the side of the support cover via a pin. Both ends of the pressure relief window are fitted with torsion springs, and the pressure relief window is opened by flipping around the pin using the elastic force of the torsion springs. A mechanical limiting assembly is provided on one side of the pressure relief window. The mechanical limiting assembly is used to lock the pressure relief window under normal conditions and release the lock in case of failure to realize the automatic opening of the second-level pressure relief assembly.

[0012] Furthermore, the mechanical limiting component includes a transmission groove formed on the support cover, a swing bar rotatably provided on the bottom surface of the transmission groove, a limit pin fixedly connected to one side of the swing bar, a pull plate fixedly connected to the other side, and a tension spring connected between one end of the pull plate and the end face of the transmission groove.

[0013] Furthermore, a guide pin and an electromagnetic relay are fixedly installed at the bottom of the transmission groove. One end of the electromagnetic relay is connected to a pull rope, which passes around the guide pin and connects to the pull plate. One end of the transmission groove is provided with a limiting protrusion, which abuts against one end of the swing bar to limit the rotation angle of the swing bar. The electromagnetic relay is electrically connected to the sensor to respond to the alarm signal output by the sensor.

[0014] Furthermore, a guide groove is provided on the side of the pressure relief window, and a locking groove is connected to the lower end of the guide groove. The end of the limiting pin slides in the guide groove and can be locked into the locking groove to achieve locking.

[0015] Furthermore, a mesh cover is installed at the bottom of the pressure relief box, and inserts are provided on the side of the mesh cover. A mounting groove is horizontally opened at the bottom of the support cover, and the inserts are slidably inserted into the mounting groove to fix the mesh cover.

[0016] Furthermore, a mesh cover is installed at the bottom of the pressure relief box, and inserts are provided on the side of the mesh cover. A mounting groove is horizontally opened at the bottom of the support cover, and the inserts are slidably inserted into the mounting groove to fix the mesh cover.

[0017] Furthermore, one end of the pressure relief window is provided with an arc-shaped guide groove, the lower end of which is connected to a transverse locking groove. The end of the limiting pin slides within the arc-shaped guide groove and can be engaged with the transverse locking groove to achieve locking.

[0018] This application also discloses the following technical solution: a hierarchical pressure relief method for low-voltage switchgear, comprising the following steps: S1. Real-time monitoring: The operating status of electronic components in the power supply cabinet is monitored in real time by smoke sensors. Smoke concentration signals, temperature signals and internal pressure signals of the cabinet are collected simultaneously and converted into fault characteristic parameters. S2. Grading judgment: The fault feature parameters are compared with the preset level threshold to identify the level to which the current fault belongs; S3, First-level pressure relief: When a first-level fault is detected, an excitation signal is output to the electromagnet, causing a change in the magnetic force of the electromagnet, thereby driving the magnetic block to detach from the electromagnet; the connecting rod then loses its support, and the top plate is popped open under the pressure of the airflow inside the cabinet, completing the first-level directional pressure relief from the top of the pressure relief box. S4. Second-level pressure relief: When a second-level fault is detected or a first-level fault is upgraded, an action signal is simultaneously output to the electromagnetic relay. The electromagnetic relay retracts the pull rope and pulls the pull plate against the elastic force of the tension spring, causing the swing bar to rotate around the axis. The limit pin then disengages from the transverse locking groove and slides along the arc-shaped guide groove. Under the elastic restoring force of the torsion spring, the pressure relief window flips open around the pin axis, completing the second-level pressure relief from both sides of the pressure relief box.

[0019] Furthermore, in step S2, a composite criterion based on smoke, temperature, and pressure is used for fault classification: When the smoke concentration is greater than the first concentration threshold and the temperature rise rate is less than the temperature rate threshold, it is determined to be a first-level fault, and only the first-level pressure relief is triggered. When the smoke concentration exceeds the second concentration threshold, or the internal pressure of the cabinet exceeds the pressure threshold, it is determined to be a second-level fault, and the first-level pressure relief and the second-level pressure relief are triggered simultaneously. Wherein, the second concentration threshold is greater than the first concentration threshold, and the smoke sensor is a composite sensor that integrates smoke detection, temperature detection and pressure detection functions.

[0020] Based on the above, the beneficial effects of the present invention are as follows: I. This invention, through the design of a power supply cabinet, air duct, and a pressure relief box located at the top of the cabinet and connected to the power supply cabinet, enables the rapid upward and discharge of high-temperature and high-pressure gas generated inside the cabinet along a preset path when a short-circuit fault occurs in electronic components. This prevents the fault gas from accumulating locally inside the power supply cabinet, thereby reducing the impact and damage to the cabinet structure caused by local overpressure. At the same time, the layered opening of the first-level pressure relief component in the middle and the second-level pressure relief components on both sides makes the pressure relief path smoother and the pressure relief process more orderly, improving the overall safety and pressure relief stability of the low-voltage switchgear under fault conditions.

[0021] Second, this invention, through the electromagnet, magnetic block, top plate, connecting rod, and sensor in the first-level pressure relief assembly, achieves a rapid response to fault smoke signals inside the cabinet. Under the trigger of the electrical signal, the top plate is promptly released from its lock, allowing it to spring open stably along the connecting rod to quickly form a central pressure relief channel. This shortens the pressure relief start-up time and facilitates the timely release of high-temperature and high-pressure gas in the early stages of a fault. Furthermore, the guiding cooperation between the connecting rod and the limiting groove ensures that the movement trajectory of the top plate is controllable, preventing the top plate from detaching from the support frame due to airflow impact. At the same time, it reduces the risk of accidental opening during normal equipment operation.

[0022] Third, this invention, through the setting of a second-level pressure relief component, mechanical limit component, torsion spring, electromagnetic relay, pull rope and guide pin, can automatically release the side pressure relief window lock when the pressure inside the cabinet further increases. The elastic energy storage of the torsion spring drives the pressure relief window to quickly flip open, further expanding the total pressure relief area on the basis of central pressure relief. The side pressure relief action can be completed without an additional power source, and the force transmission path is clear, the structure is compact, and the locking reliability is high, which can meet the rapid pressure relief requirements in the event of a large-energy electric arc fault in the cabinet.

[0023] Fourth, this invention, through the design of guide grooves, locking grooves, limit pins, and tension spring reset cooperation structure, enables the pressure relief window to smoothly and accurately reset and relock along a preset trajectory after the fault is cleared. This makes the locking and unlocking process of the pressure relief window more controllable, reduces the alignment difficulty during manual reset, and improves the stability of the component for repeated use. At the same time, the guide locking structure can also effectively prevent the pressure relief window from accidentally flipping in the opposite direction, improving the working reliability and maintenance convenience of the second-level pressure relief component during long-term operation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present invention, and are not intended to limit the present invention.

[0025] Figure 1 This is a schematic diagram of the overall structure of the low-voltage switchgear of the present invention; Figure 2 This is a schematic diagram of the internal structure of the low-voltage switchgear of the present invention; Figure 3 This is a three-dimensional schematic diagram of the pressure relief box in this invention; Figure 4 This is an exploded view of the pressure relief box in this invention; Figure 5 This is the present invention. Figure 4 Enlarged view of point A (assembly diagram of the card plate and support cover); Figure 6 This is a schematic diagram of the structure of the first-level pressure relief assembly in this invention; Figure 7 This is a schematic diagram of the mechanical limiting component in this invention; Figure 8 This is a schematic diagram of the locking state of the mechanical limiting component and the locking structure in this invention; Figure 9 This is a flowchart of the hierarchical pressure relief method for the low-voltage switchgear of the present invention.

[0026] Explanation of reference numerals in the attached figures: 10. Cabinet; 11. Power Supply Cabinet; 12. Air Duct; 20. Electronic Components; 30. Pressure Relief Box; 31. Support Cover; 32. Card Plate; 33. Hook; 34. Slot; 40. First-Level Pressure Relief Assembly; 41. Support Frame; 42. Electromagnet; 43. Limiting Slot; 44. Connecting Rod; 45. Top Plate; 46. Magnetic Block; 47. Sensor; 50. Second-Level Pressure Relief Assembly; 51. Pressure Relief Window; 52. Torsion Spring; 60. Mechanical Limiting Assembly; 61. Transmission Slot; 62. Swing Bar; 63. Limiting Pin; 64. Pull Plate; 65. Tension Spring; 66. Guide Pin; 67. Electromagnetic Relay; 68. Pull Rope; 69. Limiting Protrusion; 70. Locking Structure; 71. Guide Slot; 72. Locking Slot; 73. Reset Guide Surface; 80. Mesh Cover; 81. Insert Strip; 82. Mounting Slot. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] Unless otherwise defined, the technical or scientific terms used in this patent document shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this patent specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising," "including," etc., mean that the element or object preceding "comprising" covers the element or object listed following "comprising" or its equivalents, and do not exclude other elements or objects. Terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Example 1

[0030] This invention discloses a low-voltage switchgear with tiered pressure relief, referring to... Figure 1 and Figure 2 It includes a cabinet 10, inside which a power supply cabinet 11 and an air duct 12 are connected to each other. Electronic components 20 are installed inside the power supply cabinet 11. A pressure relief box 30 connected to the power supply cabinet 11 is provided on the top of the cabinet 10.

[0031] The cabinet 10 serves as the overall load-bearing structure, internally divided into two functional areas: a power supply cabinet 11 and an air duct 12. The power supply cabinet 11 houses electronic components 20 such as circuit breakers, disconnect switches, and instrument transformers. The air duct 12 is interconnected with the power supply cabinet 11, creating a unified airflow channel within the cabinet 10. When a short circuit fault occurs in the electronic components 20 inside the power supply cabinet 11, generating high-temperature and high-pressure gas, this gas can flow upwards through the air duct 12 to the pressure relief box 30. This provides a smooth airflow path for pressure relief and discharge within the cabinet 10, preventing the fault gas from accumulating locally inside the power supply cabinet 11 and reducing the risk of structural damage to the cabinet 10 due to excessively high local pressure. This low-voltage switchgear is suitable for typical low-voltage power distribution scenarios such as power distribution rooms in industrial plants, main power distribution rooms in commercial buildings, substations in residential communities, and low-voltage busbar sections in data centers. It operates at 220V single-phase and 380V three-phase AC voltage levels, and the load current can reach hundreds or even thousands of amperes. It provides control and protection for terminal equipment such as motors, lighting, air conditioners, and UPS, and operates under continuous load for a long time.

[0032] Reference Figure 3 and Figure 4 The pressure relief box 30 is located at the top of the cabinet 10 and is connected to the power supply cabinet 11. A first-level pressure relief assembly 40 is located in the middle of the pressure relief box 30, and second-level pressure relief assemblies 50 are located on both sides of the pressure relief box 30. In this technical solution, the first-level pressure relief assembly 40 and the second-level pressure relief assembly 50 on the pressure relief box 30 realize the layered pressure relief function inside the cabinet 10.

[0033] Specifically, when a short circuit fault occurs in electronic component 20, the first-level pressure relief assembly 40 first responds to the circuit fault signal inside the cabinet 10 to perform first-level pressure relief, opening a pressure relief channel in the middle of the pressure relief box 30 to discharge the high-temperature and high-pressure gas generated in the early stage of the fault from the cabinet 10. If the fault continues to develop and the pressure inside the cabinet further increases, the second-level pressure relief assembly 50 then responds to the fault signal and opens on both sides of the pressure relief box 30 to expand the pressure relief area to enhance the discharge capacity, thus achieving second-level pressure relief.

[0034] By adopting the above-described layered pressure relief structure, when the fault arc energy is small, the pressure relief requirement can be met by opening only the first-level pressure relief component 40, avoiding airflow impact and dust diffusion problems caused by an excessively large pressure relief area. When the fault arc energy is large, the first-level pressure relief component 40 and the second-level pressure relief component 50 open together, providing sufficient pressure relief channel area, allowing the pressure inside the cabinet to drop below the safe threshold within a safe time. Compared with the existing technology that uses a single pressure relief port, the layered pressure relief structure matches the pressure relief amount with the severity of the fault, ensuring both timely and appropriate pressure relief.

[0035] For example, in low-voltage power distribution locations with high environmental cleanliness requirements, such as data centers and cleanrooms, opening only the first-level pressure relief component 40 can effectively prevent dust diffusion and secondary pollution caused by large-area airflow impact; in densely populated locations such as industrial control rooms or commercial building power distribution rooms, the coordinated opening of the first and second levels can ensure that the pressure inside the cabinet drops rapidly below the safety threshold under high-energy fault conditions such as three-phase short circuits on the 380V bus, effectively protecting the personal safety of maintenance personnel.

[0036] Reference Figure 6 The first-level pressure relief assembly 40 includes a support frame 41 fixedly mounted on both ends of the support cover 31. A magnet 42 is fixedly mounted in the middle of the support frame 41, and limit grooves 43 are respectively formed at both ends of the support frame 41. A top plate 45 is provided on the upper end of the support frame 41, and connecting rods 44 are hinged around the lower end surface of the top plate 45. The other end of the connecting rods 44 is movably connected in the limit grooves 43. A magnetic block 46 adapted to fit and conform to the magnet 42 is provided on the side of the top plate 45, and a sensor 47 is provided at the lower end of the support frame 41.

[0037] In this technical solution, a magnet 42 is installed in the middle of the support frame 41, and a magnetic block 46 adapted to and fitted with the magnet 42 is installed on the side of the top plate 45. The top plate 45 is magnetically locked under normal conditions. When the magnet 42 is not energized, it and the magnetic block 46 are attracted to each other by magnetic force, fixing the top plate 45 to the upper end of the support frame 41. At this time, the connecting rod 44 is in a folded state, with one end hinged to the lower end face of the top plate 45 and the other end movably connected in the limiting groove 43. The connecting rod 44 plays a role in auxiliary support and motion guidance for the top plate 45. The cooperation structure between the connecting rod 44 and the limiting groove 43 ensures that the top plate 45 moves along the hinge direction of the connecting rod 44 during the opening process, preventing the top plate 45 from detaching from the support frame 41 due to airflow impact and ensuring that the movement trajectory of the top plate 45 is controllable during the depressurization process.

[0038] Furthermore, sensor 47 is located at the lower end of support frame 41, above the airflow channel inside cabinet 10. It can receive smoke signals, temperature signals, and pressure signals generated inside cabinet 10 due to short circuit faults. The signal output terminal of sensor 47 is connected to control module. Control module drives energizing magnet 42 and electromagnetic relay 67 to operate according to preset layered triggering logic based on the real-time collected values ​​of each detection parameter. When sensor 47 detects that the smoke concentration inside cabinet 10 exceeds the first smoke threshold or the temperature exceeds the first temperature threshold, control module determines that an early fault has occurred inside cabinet 10 and outputs the first trigger signal to drive energizing magnet 42. After energizing magnet 42, its magnetic pole direction changes or the magnetic field is canceled, causing the magnetic attraction force on magnetic block 46 to disappear or turn into a repulsive force. Magnetic block 46 then detaches from energizing magnet 42, and top plate 45 loses its magnetic constraint. Under the action of high-pressure gas inside cabinet 10, it bounces open along the guide direction of connecting rod 44, thereby forming a pressure relief channel in the middle of pressure relief box 30, realizing the first level of pressure relief.

[0039] In this technical solution, an electromagnetic locking method is adopted, in which the electromagnet 42 and the magnetic block 46 cooperate. Simultaneously, the response of the first-level pressure relief component 40 to the fault signal depends on the electrical signal triggering of the sensor 47. Its response speed is not limited by the inertia of the mechanical structure, enabling the top plate 45 to be released in the early stages of smoke generation from the fault arc. The electromagnetic triggering mechanism has a faster response speed than a purely mechanical pressure-triggered pressure relief structure, which is beneficial for timely discharge of high-temperature and high-pressure gas in the early stages of fault development. Furthermore, the magnetic block 46 can be designed as a wedge shape, increasing the contact area between it and the electromagnet 42. This provides a stable magnetic locking force when not energized, ensuring that the top plate 45 will not be accidentally opened due to airflow disturbances inside the cabinet 10 under normal operating conditions. Specifically, the side of the magnetic block 46 facing the electromagnet 42 is designed with a wedge-shaped contact surface, and the cone angle of the wedge-shaped contact surface ranges from 15° to 30°. This cone angle design allows the magnetic block 46 and the electromagnet 42 to form a closed magnetic circuit with surface contact. At the same time, when the top plate 45 is subjected to upward airflow pressure from inside the cabinet 10, the airflow pressure is transmitted to the magnetic block 46 through the top plate 45. The wedge-shaped contact surface decomposes the upward airflow pressure into a positive force perpendicular to the contact surface and a lateral force parallel to the contact surface. The lateral force drives the magnetic block 46 to tend to slide towards the center of the electromagnet 42, thereby enhancing the magnetic attraction and tightness between the magnetic block 46 and the electromagnet 42, forming a mechanical wedge self-locking effect. Only when the magnetic field of the electromagnet 42 is canceled or reverse-magnetized after it is energized will the magnetic attraction force disappear, the wedge self-locking effect be released, and the top plate 45 be able to be popped open. Through the conical angle fitting design of the wedge-shaped magnetic block 46, the first-level pressure relief component 40 has a dual holding force of magnetic attraction locking and mechanical wedge self-locking under normal conditions, which significantly improves the vibration resistance and anti-accidental opening capability of the top plate 45 during the long-term operation of the cabinet 10.

[0040] Furthermore, the lower end of the connecting rod 44 is provided with an enlarged hinge head, and the limiting groove 43 is a longitudinally extending strip groove with a tapering stop at the upper end. Under normal conditions, the hinge head is located at the lower end of the limiting groove 43, and the connecting rod 44 is in a folded support state. When the top plate 45 is pushed open upward by the high-pressure airflow inside the cabinet, the hinge head slides upward along the limiting groove 43 until it is mechanically limited at the tapering stop at the upper end of the limiting groove 43, thereby constraining the top plate 45 to the open position above the support frame 41 and preventing the top plate 45 from completely detaching from the support frame 41 under the impact of the airflow. Through the cooperation of the limiting groove 43 and the sliding stop of the hinge head at the lower end of the connecting rod 44, the top plate 45 has both stable motion trajectory guidance and mechanical anti-detachment function during the opening process, which not only ensures the smooth formation of the central pressure relief channel, but also avoids the top plate 45 flying off and causing secondary damage to personnel and equipment outside the cabinet 10.

[0041] Reference Figure 7 and Figure 8 The second-level pressure relief assembly 50 includes a pressure relief window 51 hinged to the side of the support cover 31 via a pin. Torsion springs 52 are fitted at both ends of the pressure relief window 51, and the pressure relief window 51 opens by flipping around the pin using the elastic force of the torsion springs 52. A mechanical limiting assembly 60 is provided on one side of the pressure relief window 51. The mechanical limiting assembly 60 is used to lock the pressure relief window 51 under normal conditions and release the lock in case of a malfunction to achieve automatic opening of the second-level pressure relief assembly 50.

[0042] The pressure relief window 51 is hinged to the side of the support cover 31 via a pin, allowing it to rotate between the closed and open positions around the pin. A torsion spring 52 is fitted onto both ends of the pressure relief window 51 and is in a pre-tensioned state; its elastic restoring force provides the driving force for the rotation and opening of the pressure relief window 51. Under normal conditions, the mechanical limit assembly 60 applies a locking constraint to the pressure relief window 51, and the elastic force of the torsion spring 52 is balanced by the locking force of the mechanical limit assembly 60, keeping the pressure relief window 51 in the closed position. When a fault occurs inside the cabinet 10 and the first-level pressure relief is insufficient to reduce the pressure inside the cabinet to a safe value, the control module outputs a second trigger signal to drive the electromagnetic relay 67 to operate. The mechanical limit assembly 60 releases the locking of the pressure relief window 51, and the elastic force of the torsion spring 52 drives the pressure relief window 51 to rotate around the pin to the open position, thereby forming pressure relief channels on both sides of the pressure relief box 30, achieving the second-level pressure relief.

[0043] In this technical solution, by employing a torsion spring 52 to provide elastic preload, the pressure relief window 51 can automatically flip open by its own elastic energy storage after the mechanical limiting component 60 is released and locked, without the need for an additional drive device or external power source. The structure is compact and the mechanical structure offers high reliability. Simultaneously, the pressure relief window 51 is located on both sides of the pressure relief box 30, and its pressure relief area overlaps with the pressure relief area of ​​the top plate 45 of the first-level pressure relief component 40. This effectively expands the total pressure relief area of ​​the cabinet 10 in the second-level pressure relief stage, meeting the rapid pressure relief requirements when the fault energy is large. Example 2

[0044] Based on Example 1, referring to Figures 3 to 5 This embodiment further explains the assembly structure of the pressure relief box 30, the transmission mechanism of the mechanical limiting component 60, and the locking structure of the pressure relief window 51.

[0045] The pressure relief box 30 includes a support cover 31 fixedly mounted on the upper end of the cabinet 10. The support cover 31 is inverted U-shaped. A retaining plate 32 is provided at the end of the support cover 31. A hook 33 is provided at the end of the retaining plate 32. A slot 34 is provided on the side of the support cover 31. The hook 33 is adapted to engage in the slot 34 to fix the retaining plate 32 and the support cover 31.

[0046] In this technical solution, the support cover 31 adopts an inverted U-shaped structure, creating an open-top accommodating space inside the pressure relief box 30. This space connects to the power supply cabinet 11 inside the cabinet 10, providing a channel for the upward discharge of fault gases. Hooks 33 are provided on the clamping plate 32, and slots 34 are opened on the side of the support cover 31. The clamping plate 32 and the support cover 31 are fixedly assembled using a matching snap-fit ​​method between the hooks 33 and the slots 34, eliminating the need for bolts or other fasteners and facilitating the disassembly and maintenance of the pressure relief box 30. When it is necessary to inspect the electronic components 20 inside the cabinet 10, the operator can remove the hooks 33 from the slots 34 and quickly disassemble the clamping plate 32 to open one end of the pressure relief box 30, improving the convenience of maintenance operations.

[0047] Reference Figure 7 The mechanical limiting component 60 includes a transmission groove 61 formed on the support cover 31. A swing bar 62 is rotatably provided on the bottom surface of the transmission groove 61. A limit pin 63 is fixedly connected to one side of the swing bar 62, and a pull plate 64 is fixedly connected to the other side. A tension spring 65 is connected between one end of the pull plate 64 and the end face of the transmission groove 61.

[0048] A guide pin 66 and an electromagnetic relay 67 are fixedly mounted at the bottom of the transmission groove 61. One end of the electromagnetic relay 67 is connected to a pull rope 68, which passes around the guide pin 66 and connects to the pull plate 64. One end of the transmission groove 61 is provided with a limiting protrusion 69, which abuts against one end of the swing bar 62 to limit the rotation angle of the swing bar 62. The electromagnetic relay 67 is electrically connected to the sensor 47 to respond to the alarm signal output by the sensor 47.

[0049] Under normal conditions, the tension spring 65 is in a naturally extended or slightly stretched state. The swing bar 62 is held in the locked position by the elastic force of the tension spring 65. The limiting protrusion 69 abuts against one end of the swing bar 62, limiting the rotation angle of the swing bar 62 and preventing the swing bar 62 from deviating from the locked position due to external disturbances. At this time, the limiting pin 63 on one side of the swing bar 62 is inserted into the locking structure of the pressure relief window 51, applying a locking constraint to the pressure relief window 51.

[0050] When the electromagnetic relay 67 receives a trigger signal and actuates, it applies a pulling force to the pull plate 64 via the pull rope 68. After the pull rope 68 bypasses the guide pin 66 and changes the direction of force transmission, it transmits the pulling force to the pull plate 64, driving it to move against the elastic force of the tension spring 65. Since the pull plate 64 is fixedly connected to the swing bar 62, the movement of the pull plate 64 causes the swing bar 62 to swing around its rotation center within the transmission groove 61. The limiting pin 63 on the other side of the swing bar 62 then disengages from the locking structure of the pressure relief window 51, releasing the lock on the pressure relief window 51. The pressure relief window 51 automatically flips open under the elastic force of the torsion spring 52, completing the second level of pressure relief.

[0051] By setting guide pin 66 to guide the transmission path of pull rope 68, pull rope 68 can realize the direction conversion of force within the limited space of transmission groove 61, ensuring that the output pull force of electromagnetic relay 67 can be effectively transmitted to pull plate 64, thereby improving the space utilization and force transmission efficiency of transmission mechanism. Furthermore, the guide pin 66 is disposed between the electromagnetic relay 67 and the pull plate 64. After the pull rope 68 passes around the guide pin 66, its pulling direction changes by 90° to 120°, so that the horizontal output pulling force of the electromagnetic relay 67 is converted into an oblique pulling force on the pull plate 64. The distance from the rotation center of the swing bar 62 to the fixed connection point of the pull plate 64 is L1, and the distance from the rotation center to the fixed connection point of the limit pin 63 is L2, and L1 is greater than L2. The swing bar 62 constitutes a force-saving lever with the rotation center as the fulcrum. When the electromagnetic relay 67 applies a pulling force F1 to the pull plate 64 through the pull rope 68, the pull plate 64 drives the swing bar 62 to swing, and the limit pin 63 obtains an unlocking force F2 along the exit direction of the locking groove 72. The unlocking force F2 is greater than the pulling force F1. By utilizing the force direction conversion of the guide pin 66 and the lever-saving design of the swing bar 62, the electromagnetic relay 67 only needs to provide a small electromagnetic attraction force to overcome the elastic restoring force of the tension spring 65 and the locking resistance of the limiting pin 63 in the transverse locking groove 72, thus achieving reliable unlocking of the pressure relief window 51. This also reduces the size of the electromagnetic relay 67, making the overall structure of the mechanical limiting assembly 60 more compact. By connecting the tension spring 65 to the end face of the pull plate 64 and the transmission groove 61, when the electromagnetic relay 67 is not activated, the elastic force of the tension spring 65 holds the swing bar 62 in the locked position, ensuring that the pressure relief window 51 will not be accidentally opened due to vibration or airflow disturbance under normal operating conditions, thereby improving the locking reliability of the mechanical limiting assembly 60.

[0052] Furthermore, referring to Figure 8 The pressure relief window 51 has an arc-shaped guide groove 71 on its side. The lower end of the guide groove 71 is connected to a horizontal locking groove 72. The end of the limiting pin 63 is slidably fitted in the guide groove 71 and can be inserted into the locking groove 72 to achieve locking.

[0053] In this technical solution, the arc-shaped contour of the guide groove 71 is adapted to the movement trajectory of the pressure relief window 51 rotating around the pin axis, so that the limiting pin 63 can slide along the guide groove 71 during the closing process of the pressure relief window 51, playing a role in motion guidance. When the pressure relief window 51 moves to the closed position, the limiting pin 63 slides along the guide groove 71 to its lower end, and under the action of the elastic restoring force of the swing bar 62, it is engaged in the locking groove 72 that communicates with the lower end of the guide groove 71. A mechanical locking engagement is formed between the limiting pin 63 and the locking groove 72, preventing the pressure relief window 51 from rotating in the opposite direction, thereby achieving reliable locking of the pressure relief window 51.

[0054] The locking structure, combining the guide groove 71 and the locking groove 72, ensures that the locking and unlocking processes of the pressure relief window 51 both follow a preset groove trajectory, resulting in smooth and controllable movement. The guide groove 71 automatically guides the limiting pin 63 into the locking position when the pressure relief window 51 is reset and closed, facilitating the reset operation of the pressure relief window 51 after troubleshooting. The guide groove 71 is arc-shaped. Furthermore, the center of curvature of the arc-shaped guide groove 71 is eccentrically positioned with respect to the pin center of the pressure relief window 51, and the tangent direction of the lower end of the arc-shaped guide groove 71 is perpendicular to the groove depth direction of the transverse locking groove 72. When the pressure relief window 51 is in the closed position, the limiting pin 63, under the elastic force of the tension spring 65, engages with the transverse locking groove 72. At this time, a self-locking wedge force is formed between the limiting pin 63 and the groove wall of the arc-shaped guide groove 71, and the pressure relief window 51 is further secured by the elastic force of the torsion spring 52. Under the action of the restoring force, a flipping tendency force is applied to the limiting pin 63. This flipping tendency force is transmitted to the limiting pin 63 through the groove wall of the transverse locking groove 72 and is decomposed into a pressing component force pointing towards the locking position of the swing bar 62, thereby enhancing the locking stability of the limiting pin 63 in the transverse locking groove 72. Only when the electromagnetic relay 67 applies a sufficiently large unlocking pull force to the pull plate 64 through the pull rope 68 can the limiting pin 63 overcome the self-locking wedge force and exit the transverse locking groove 72. Through the eccentric curvature and vertical connection design of the arc-shaped guide groove 71 and the transverse locking groove 72, the mechanical self-locking of the pressure relief window 51 under normal conditions is realized, which significantly improves the vibration resistance and anti-accidental opening capability of the second-level pressure relief assembly 50 during the long-term operation of the cabinet 10.

[0055] Reference Figure 4A mesh cover 80 is installed at the bottom of the pressure relief box 30. The mesh cover 80 has inserts 81 on its sides, and a horizontal mounting groove 82 is provided at the bottom of the support cover 31. The inserts 81 are slidably inserted into the mounting groove 82 to fix the mesh cover 80. The mesh cover 80 at the bottom of the pressure relief box 30 shields and filters the connection between the power supply cabinet 11 and the pressure relief box 30. The mesh cover 80 can prevent foreign objects and small animals from entering the power supply cabinet 11, reducing the risk of short circuit faults caused by foreign object intrusion. At the same time, the mesh structure of the mesh cover 80 does not obstruct the flow of fault gas, ensuring the unobstructed flow of the pressure relief channel. The mesh cover 80 is fixed to the bottom of the support cover 31 by sliding insertion of the inserts 81 into the mounting groove 82. The structure is simple and easy to install and remove, facilitating regular cleaning or replacement of the mesh cover 80. Furthermore, the mesh cover 80 has a multi-layer composite structure, including a first protective layer, a buffer cavity layer, and a second filter layer from top to bottom; the first protective layer is made of coarse-pore metal mesh to block rodents and large foreign objects from entering; the second filter layer is made of fine-pore flame-retardant fiber mesh or densely textured metal mesh to intercept dust and fine particles; the first protective layer and the second filter layer are separated by a buffer cavity layer with a set distance maintained by a circumferential frame. This buffer cavity layer causes the high-speed airflow to expand and decelerate after penetrating the first protective layer, and then pass evenly through the second filter layer, avoiding the single-layer dense mesh from being torn or blocked instantly under the impact of high-pressure airflow. The end of the insert 81 is provided with an enlarged head, and the end of the mounting groove 82 is provided with a corresponding constricted locking section. When the insert 81 slides into the mounting groove 82 to its limit position, the enlarged head and the constricted locking section are interference-engaged. Under normal conditions, this interference engagement prevents the mesh cover 80 from slipping out of the mounting groove 82 due to airflow pulsation inside the cabinet 10 or external vibration. When emergency maintenance is required, applying axial tension can cause the enlarged head to overcome the elastic constraint of the constricted locking section and disengage, enabling rapid replacement of the mesh cover 80. Through the gradient filtration and buffer cavity design of the multi-layer composite mesh cover 80, the risk of pressure relief failure due to mesh blockage is significantly reduced while ensuring long-term unobstructed pressure relief channels. Furthermore, the interference engagement between the enlarged head at the end of the insert 81 and the constricted locking section at the end of the mounting groove 82 ensures that the mesh cover 80 remains reliably fixed under normal operating vibration and high-pressure airflow impact, without hindering manual disassembly and assembly during regular maintenance.

[0056] Furthermore, sensor 47 is a composite sensor integrating smoke detection, temperature detection, and pressure detection functions. In this technical solution, by setting sensor 47 as a composite sensor integrating smoke detection, temperature detection, and pressure detection functions, sensor 47 can simultaneously monitor the smoke concentration, temperature changes, and pressure changes inside cabinet 10. When a short circuit fault occurs inside cabinet 10, the electric arc will simultaneously generate three physical signals: smoke, high temperature, and high pressure. By comprehensively judging multiple signals, the composite sensor can reduce the probability of false triggering by a single signal, thereby improving the accuracy and reliability of fault detection. Compared to sensors that only use a single smoke detection function, the composite sensor, through multi-parameter joint judgment, can output an alarm signal in advance when the smoke concentration has not yet reached the trigger threshold but the temperature or pressure has already abnormally increased, which is beneficial to improving the timeliness of pressure relief response. Example 3

[0057] Based on Embodiments 1 and 2, this embodiment describes the working process and control method of the hierarchical pressure relief low-voltage switchgear in a low-voltage power distribution scenario. Specifically: Reference Figures 1 to 9 This low-voltage switchgear operates under load for extended periods in low-voltage power distribution scenarios such as industrial plants, commercial buildings, and residential communities. Due to factors such as accelerated insulation degradation caused by humid environments, increased contact wear caused by inrush current during motor startup, and intrusion of rodents and foreign objects, the probability of internal short-circuit faults in feeder cabinet 11 is relatively high. The layered pressure relief structure can adaptively respond to different low-voltage fault energy levels.

[0058] Under normal operating conditions, the electronic components 20 inside the cabinet 10 are functioning normally, and there are no abnormal changes in smoke, temperature, or pressure inside the power supply cabinet 11. At this time, the magnet 42 in the first-level pressure relief assembly 40 is not energized, and the wedge-shaped magnet 46 and the magnet 42 are attracted to each other by magnetic force, fixing the top plate 45 to the upper end of the support frame 41. The connecting rod 44 is in a folded support state, and the top plate 45 closes the pressure relief channel in the middle of the pressure relief box 30. The pressure relief window 51 in the second-level pressure relief assembly 50 is in the closed position, the limit pin 63 is engaged in the transverse locking groove 72 to lock the pressure relief window 51, the torsion spring 52 is in an elastic pre-tensioned state, the tension spring 65 in the mechanical limit assembly 60 keeps the swing bar 62 in the locked position, and the electromagnetic relay 67 is in an inactive state. The mesh cover 80 is fixed to the bottom of the pressure relief box 30 to shield and protect the connection between the power supply cabinet 11 and the pressure relief box 30.

[0059] When a short circuit occurs in the electronic components 20 inside the power supply cabinet 11 due to insulation aging, poor contact, or foreign object intrusion, the short-circuit arc generates high-temperature, high-pressure gas and smoke. The smoke diffuses upward along the air duct 12, passes through the mesh cover 80, and enters the internal space of the pressure relief box 30. The smoke concentration, temperature, and pressure inside the cabinet 10 then undergo abnormal changes. The control system responds sequentially according to the following steps: Step S1 (Real-time Monitoring): After the cabinet 10 is put into operation, the smoke sensor 47 installed at the lower end of the support frame 41 continuously monitors the internal environment of the power supply cabinet 11 in real time. It synchronously collects smoke concentration signals, temperature signals, and internal pressure signals at preset sampling intervals, and converts these three analog signals into fault characteristic parameters through an internal signal conditioning circuit. In this embodiment, the sampling interval can be set from 10 milliseconds to 100 milliseconds to balance response speed and processing load. The smoke concentration is characterized by the concentration of smoke particles per unit volume (mg / m³), the temperature signal is the internal air temperature (°C) of the power supply cabinet 11, and the temperature rise rate (°C / s) per unit time is calculated simultaneously. The pressure signal is the pressure difference (kPa) between the inside of the power supply cabinet 11 and the external environment.

[0060] Step S2 (Grading Judgment): The smoke sensor 47 compares the fault characteristic parameters collected in real time in step S1 with the preset grading threshold, and identifies the current fault grading level based on a composite criterion of smoke, temperature, and pressure. The specific judgment rules are as follows: When the smoke concentration is greater than the first concentration threshold N1 and the temperature rise rate is less than the temperature rate threshold V, it is determined to be a first-level fault, and only the first-level pressure relief component 40 is triggered. When the smoke concentration is greater than the second concentration threshold N2, or the internal pressure of the cabinet exceeds the second pressure threshold, it is determined to be a second-level fault, and the first-level pressure relief component 40 and the second-level pressure relief component 50 are triggered simultaneously. When sensor 47 detects that the pressure directly exceeds the third pressure threshold (higher than the second pressure threshold), the control module skips the delay logic and simultaneously outputs the first trigger signal and the second trigger signal. The first-level pressure relief component 40 and the second-level pressure relief component 50 are activated in concert to deal with the emergency situation where the fault arc energy is extremely high and the pressure inside the cabinet rises sharply.

[0061] The second concentration threshold N2 is greater than the first concentration threshold N1. The specific values ​​of each parameter can be determined in combination with the volume of the cabinet 10 and the rated parameters of the electronic components 20. For example, N1 can be 0.05 mg / m³ to 0.10 mg / m³, N2 can be 0.15 mg / m³ to 0.30 mg / m³, the temperature rate threshold V can be 5℃ / s, and the pressure threshold can be 5 kPa to 15 kPa.

[0062] In this solution, by setting a composite criterion of smoke, temperature, and pressure, different stages of fault development can be effectively distinguished: when only slight smoke appears inside the power supply cabinet 11 and the temperature change is gradual, it indicates that the fault arc energy is small and the pressure rise inside the cabinet is limited, requiring only the opening of the top plate 45 to meet the pressure relief requirement; when the smoke concentration rises sharply or the pressure inside the cabinet rises sharply, it indicates that the fault arc energy is large, and the pressure relief area must be expanded simultaneously to avoid structural damage to the cabinet 10. Compared with single-parameter threshold judgment, this composite criterion can effectively reduce the probability of false triggering caused by sensor drift, instantaneous disturbances, etc., while avoiding excessive pressure relief under low fault energy conditions, which could lead to airflow impact and dust diffusion problems.

[0063] Step S3 (First-level pressure relief): When step S2 determines that a first-level fault has occurred, the smoke sensor 47 outputs an excitation signal to the energizing magnet 42. The energizing magnet 42 switches from an unenergized state to an energized state, and its magnetic field characteristics change accordingly. The magnetic attraction force between the wedge-shaped magnetic block 46 and the energizing magnet 42 disappears or turns into a repulsive force, and the wedge-shaped magnetic block 46 detaches from the energizing magnet 42. After the top plate 45 loses its magnetic constraint, it springs open along the hinged guide direction of the connecting rod 44 under the upward thrust of the high-pressure gas inside the cabinet 10. The connecting rod 44 extends from a folded state to an unfolded state, guiding the top plate 45 to move upward and maintain a stable trajectory. After the top plate 45 opens, a pressure relief channel is formed in the middle of the pressure relief box 30. The high-temperature and high-pressure gas inside the cabinet 10 is discharged upward to the outside of the cabinet 10 through this pressure relief channel, realizing the first-level pressure relief. At this stage, the pressure relief channel area in the middle of the pressure relief box 30 is determined by the opening area of ​​the top plate 45, which is suitable for working conditions where the fault arc energy is small and the pressure rise inside the cabinet is limited. This working condition corresponds to low-energy fault scenarios such as single-phase grounding arc and auxiliary control circuit short circuit. Such scenarios are common in residential substations and commercial building power distribution rooms. Opening only the middle top plate 45 is sufficient to meet the pressure relief requirements, avoiding unnecessary impact on surrounding equipment due to an excessively large pressure relief area.

[0064] Simultaneously with the output of the first trigger signal, the control module starts a delay timer with a delay duration set to T (e.g., 50 milliseconds to 500 milliseconds). After the delay, the control module judges the real-time data from the pressure detection channel: if the internal pressure of cabinet 10 has dropped below the second pressure threshold, it indicates that the first-level pressure relief has met the pressure release requirements, the control module does not output the second trigger signal, the electromagnetic relay 67 remains inactive, and the second-level pressure relief component 50 remains closed; if the internal pressure of cabinet 10 is still higher than the second pressure threshold or continues to rise, it indicates that the fault arc energy is large and the first-level pressure relief capacity is insufficient, the control module then outputs the second trigger signal and proceeds to step S4.

[0065] Step S4 (Second-Level Pressure Relief): When step S2 directly determines a second-level fault, or when the fault characteristic parameters are upgraded to the second-level fault criteria after processing in step S3, the smoke sensor 47 outputs an action signal to the electromagnetic relay 67. Specifically: when the fault characteristic parameters detected by the smoke sensor 47 for the first time meet the second-level fault criteria, the smoke sensor 47 executes this step S4 simultaneously with step S3; when the initial detected parameters only meet the first-level fault criteria, the control system first executes step S3 to trigger the first-level pressure relief, continuously monitors during the observation period, and if the monitored parameters are upgraded to the second-level fault criteria, this step is triggered immediately; if the monitored parameters tend to stabilize or decrease during the observation period, the first-level pressure relief is maintained and the second-level pressure relief is no longer triggered.

[0066] After receiving the action signal, the electromagnetic relay 67 applies a pulling force to the pull plate 64 via the pull rope 68. The pull rope 68 changes the direction of force transmission via the guide pin 66 and effectively transmits the pulling force to the pull plate 64. Under the action of the pulling force, the pull plate 64 overcomes the elastic force of the tension spring 65 and moves, causing the swing bar 62, which is fixedly connected to it, to swing around the rotation center in the transmission groove 61. The limiting pin 63 on one side of the swing bar 62 exits laterally from the transverse locking groove 72 of the pressure relief window 51 and slides along the arc-shaped contour of the arc-shaped guide groove 71, releasing the locking constraint on the pressure relief window 51. Driven by the elastic restoring force of the torsion spring 52, the pressure relief window 51 flips around the pin shaft to the open position. After the pressure relief windows 51 on both sides of the pressure relief box 30 are opened, together with the already opened top plate 45 in the middle, they form an expanded pressure relief area. The high-temperature and high-pressure gas inside the cabinet 10 is simultaneously discharged to the outside through the pressure relief channels in the middle and on both sides, realizing the second level of pressure relief. At this stage, the total pressure relief area of ​​cabinet 10 is formed by the superposition of the opening area of ​​the top plate 45 and the opening areas of the pressure relief windows 51 on both sides, which meets the rapid pressure relief requirements when the fault arc energy is large and the pressure inside the cabinet rises sharply. This working condition corresponds to high-energy fault scenarios such as three-phase short circuit of 380V bus and arc of large-capacity motor circuit. Such scenarios are particularly dangerous in the low-voltage bus section of industrial plant power distribution room and data center. The short circuit current of low-voltage system can be as high as tens of thousands of amperes. The superimposed pressure relief area formed by the coordinated opening of the pressure relief channels in the middle and on both sides can ensure that the pressure inside the cabinet is effectively reduced within a safe time, preventing cabinet explosion and fire from spreading and causing harm to surrounding electrical equipment and maintenance personnel. It should be noted that the above steps S3 and S4 form a progressive feedback control link through the delay timer T, rather than a simple parallel trigger: after the first-level pressure relief is performed in step S3, the control system does not immediately activate the second-level pressure relief, but enters an observation window period. Only when the internal pressure of the cabinet 10 fails to effectively drop below the second pressure threshold or shows a continuous upward trend during the observation window period is the second-level pressure relief in step S4 triggered. This progressive control logic ensures that the activation decision of the second-level pressure relief component 50 is based on the feedback of the actual effect of the first-level pressure relief, avoiding the accidental opening of the pressure relief windows 51 on both sides when the fault energy is small but the parameters fluctuate instantaneously. Thus, while ensuring sufficient pressure relief, the closed integrity of the pressure relief box 30 is maintained to the maximum extent, reducing the risk of dust diffusion caused by unnecessary expansion of the pressure relief area in environmentally sensitive places such as data centers and clean rooms.

[0067] After the short circuit fault inside the cabinet 10 is cleared and the electronic components 20 are repaired and restored to normal, the operator manually resets the pressure relief box 30. First, the top plate 45 is pressed down onto the upper surface of the support frame 41, the connecting rod 44 is folded back from the unfolded state, and the wedge-shaped magnet 46 and the de-energized electromagnet 42 are magnetically attracted again, and the top plate 45 returns to the closed position. Then, the pressure relief window 51 is manually flipped around the pin to the closed position. During the flipping process, the limit pin 63 slides into the arc-shaped guide groove 71. When the pressure relief window 51 moves to the fully closed position, the limit pin 63 is automatically engaged in the transverse locking groove 72 under the elastic restoring force of the swing bar 62 and the tension spring 65, thus relocking the pressure relief window 51. The guiding effect of the arc-shaped guide groove 71 allows the limit pin 63 to automatically align and slide into the locking position along the preset trajectory during the reset process, reducing the difficulty of manual alignment for the operator. After the reset is completed, the pressure relief box 30 returns to its closed configuration under normal operating conditions, and the cabinet 10 has the ability to perform layered pressure relief again.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tiered pressure relief low-voltage switchgear, comprising a cabinet (10), wherein the cabinet (10) contains interconnected power supply cabinets (11) and air ducts (12), and the power supply cabinets (11) contain electronic components (20), characterized in that: The top of the cabinet (10) is provided with a pressure relief box (30) that is connected to the power supply cabinet (11). When the electronic component (20) has a short circuit fault, the pressure relief box (30) automatically opens to realize the layered pressure relief inside the cabinet (10). The pressure relief box (30) is provided with a first-level pressure relief component (40) in the middle, which is used to perform first-level pressure relief in response to circuit faults inside the cabinet (10); the pressure relief box (30) is provided with second-level pressure relief components (50) on both sides, which are used to perform second-level pressure relief in response to circuit fault signals inside the cabinet (10).

2. The low-voltage switchgear according to claim 1, characterized in that, The pressure relief box (30) includes a support cover (31) fixedly installed on the upper end of the cabinet (10). The support cover (31) is in the shape of an inverted U. The end of the support cover (31) is provided with a card plate (32). The end of the card plate (32) is provided with a hook (33). The side of the support cover (31) is provided with a slot (34). The hook (33) is adapted to be engaged in the slot (34) to fix the card plate (32) and the support cover (31) together.

3. The low-voltage switchgear according to claim 2, characterized in that, The first-level pressure relief assembly (40) includes a support frame (41) fixedly installed at both ends of the support cover (31). A magnet (42) is fixedly installed in the middle of the support frame (41), and limit grooves (43) are opened at both ends respectively. A top plate (45) is installed on the upper end of the support frame (41), and a connecting rod (44) is hinged around the lower end surface of the top plate (45). The other end of the connecting rod (44) is movably connected in the limit groove (43).

4. The low-voltage switchgear according to claim 3, characterized in that, The top plate (45) has a magnetic block (46) on its side that is adapted to fit the magnet (42); the lower end of the support frame (41) is provided with a sensor (47), which can receive the smoke signal inside the cabinet (10) and trigger the magnet (42) to be energized, so that the magnetic block (46) is detached from the magnet (42), thereby popping the top plate (45) open.

5. The low-voltage switchgear according to claim 4, characterized in that, The second-level pressure relief assembly (50) includes a pressure relief window (51) hinged to the side of the support cover (31) by a pin. Torsion springs (52) are sleeved at both ends of the pressure relief window (51). The pressure relief window (51) is opened by flipping around the pin by the elastic force of the torsion springs (52). A mechanical limiting assembly (60) is provided on one side of the pressure relief window (51). The mechanical limiting assembly (60) is used to lock the pressure relief window (51) under normal conditions and release the lock in case of failure to realize the automatic opening of the second-level pressure relief assembly (50).

6. The low-voltage switchgear according to claim 5, characterized in that, The mechanical limiting assembly (60) includes a transmission groove (61) formed on the support cover (31). The bottom surface of the transmission groove (61) is rotatably provided with a swing bar (62). One side of the swing bar (62) is fixedly connected to a limiting pin (63), and the other side is fixedly connected to a pull plate (64). One end of the pull plate (64) is connected to the end face of the transmission groove (61) with a tension spring (65).

7. The low-voltage switchgear according to claim 6, characterized in that, The low-voltage switchgear according to claim 6 is characterized in that a guide pin (66) and an electromagnetic relay (67) are fixedly provided at the bottom of the transmission groove (61), one end of the electromagnetic relay (67) is connected to a pull rope (68), the pull rope (68) passes around the guide pin (66) and is connected to the pull plate (64); one end of the transmission groove (61) is provided with a limiting protrusion (69), the limiting protrusion (69) abuts against one end of the swing bar (62) to limit the rotation angle of the swing bar (62); the electromagnetic relay (67) is electrically connected to the sensor (47) to respond to the alarm signal output by the sensor (47).

8. The low-voltage switchgear according to claim 6, characterized in that, The pressure relief window (51) has a guide groove (71) on its side. The lower end of the guide groove (71) is connected to a locking groove (72). The end of the limiting pin (63) is slidably engaged in the guide groove (71) and can be inserted into the locking groove (72) to achieve locking.

9. The low-voltage switchgear according to claim 2, characterized in that, The bottom of the pressure relief box (30) is equipped with a mesh cover (80), and the side of the mesh cover (80) is provided with a strip (81). The bottom of the support cover (31) is horizontally provided with an installation groove (82), and the strip (81) is slidably inserted into the installation groove (82) to fix the mesh cover 80.

10. A tiered pressure relief method for a low-voltage switchgear, applied to the low-voltage switchgear according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Real-time monitoring: The operating status of electronic components (20) in the power supply cabinet (11) is monitored in real time by the smoke sensor (47), and the smoke concentration signal, temperature signal and internal pressure signal of the cabinet are collected simultaneously and converted into fault characteristic parameters. S2. Grading judgment: The fault feature parameters are compared with the preset level threshold to identify the level to which the current fault belongs; S3, First-level pressure relief: When a first-level fault is detected, an excitation signal is output to the energizer (42), causing the magnetic force of the energizer (42) to change, thereby driving the magnetic block (46) to detach from the energizer (42); the connecting rod (44) then loses its support, and the top plate (45) is ejected under the pressure of the airflow inside the cabinet, completing the first-level directional pressure relief from the top of the pressure relief box (30); S4, Second-level pressure relief: When the fault is determined to be a second-level fault or the first-level fault is upgraded, an action signal is output to the electromagnetic relay (67) simultaneously. The electromagnetic relay (67) retracts the pull rope (68) and pulls the pull plate (64) against the elastic force of the tension spring (65), causing the swing bar (62) to rotate around the axis. The limit pin (63) then disengages from the transverse locking groove (72) and slides along the arc-shaped guide groove (71). The pressure relief window (51) flips open around the pin under the elastic restoring force of the torsion spring (52), completing the second-level pressure relief from both sides of the pressure relief box (30).

11. The tiered pressure relief method according to claim 10, characterized in that, In step S2, a composite criterion based on smoke, temperature, and pressure is used for fault classification: When the smoke concentration is greater than the first concentration threshold and the temperature rise rate is less than the temperature rate threshold, it is determined to be a first-level fault, and only the first-level pressure relief is triggered. When the smoke concentration exceeds the second concentration threshold, or the internal pressure of the cabinet exceeds the pressure threshold, it is determined to be a second-level fault, and the first-level pressure relief and the second-level pressure relief are triggered simultaneously. Wherein, the second concentration threshold is greater than the first concentration threshold, and the smoke sensor (47) is a composite sensor that integrates smoke detection, temperature detection and pressure detection functions.

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