A separate high-low voltage distribution cabinet based on passive three-criteria aerodynamic logic

Abstract

The application discloses a partition type high-low voltage power distribution cabinet based on passive three-criterion pneumatic logic, which comprises at least two electrical compartments, a shared pressure relief channel and a selective pressure relief module. The module is provided with a direction discrimination element, a pressure rise rate discrimination element, an absolute pressure discrimination element and a mechanical AND gate; the rate discrimination element is connected with the same pressure tapping through a fast branch and a damping delay branch to form two sampling cavities. Only when the three inputs of the pressure difference direction, the pressure rise rate and the absolute pressure are simultaneously established within the discrimination time window, the mechanical AND gate releases a linkage sliding block, which drives a backflow prevention door to the position first, and then releases the pressure through the main pressure relief door after the position permission element releases the locking of the main pressure relief door; the channel side pressure cannot form a three-input combination, and the non-fault compartment is closed. Without sensors, controllers and power supplies, internal electric arcs, slow pressure differences and channel back pressures can be distinguished, and pressure relief is carried out after isolation.

Description

Technical Field

[0001] This invention relates to the field of safety protection technology for complete sets of electrical equipment, and particularly to a compartmentalized high and low voltage distribution cabinet that passively identifies internal arc faults using three pneumatic criteria: differential pressure direction, pressure rise rate, and absolute pressure, and releases pressure according to the permitted sequence of releasing the main pressure relief valve only after the anti-backflow door is in place. The distribution cabinet can be a low-voltage switchgear with a rated voltage of 0.4 kV, an AC metal-enclosed switchgear of 3.6 kV to 40.5 kV, or a combined power distribution equipment containing a high-voltage incoming line unit and a low-voltage distribution unit. Background Technology

[0002] High and low voltage switchgear typically consists of compartments such as busbar compartments, circuit breaker compartments, cable compartments, and instrument compartments, formed by metal partitions. In the event of poor contact, insulation degradation, short circuits caused by foreign objects, or misoperation, internal electric arcs may occur within the compartments, generating high-temperature, high-pressure gases, molten metal particles, and conductive fumes for a short period. To control the structural load on the cabinet, existing equipment often features pressure relief covers on the top of each compartment, or connects multiple compartments to a common pressure relief channel at the top or rear of the cabinet.

[0003] For example, CN101291045B discloses a structure with multiple compartments leading to a pressure relief channel; CN111431043B discloses a switch compartment and a cable compartment connected to a pressure relief chamber via a one-way valve; WO2012067861A2 discloses a lightweight pressure relief flap resisting reverse pressure from the pressure relief channel; and US20140133071A1 discloses a flap in a faulty compartment that further opens while flaps in other compartments are closed and locked by pressure from a common channel. Therefore, simply setting up a one-way valve, or merely using the back pressure of the common channel to close the flaps in non-faulty compartments, is insufficient to reliably constitute inventiveness.

[0004] Existing pressure-type flaps typically use exceeding a single pressure threshold as the activation condition. False activation may occur when this threshold is reached during maintenance inflation, rapid door closing, fan pulsation, or external channel pressure waves. Increasing the opening threshold to reduce false activation would delay the initial depressurization of the internal arc. Furthermore, even if the pressure relief door and anti-backflow door are linked by the same mechanism, releasing the main pressure relief door before confirming the anti-backflow door is in position could create tolerances, jamming, or rebound, potentially causing temporary blockage. Implementing multi-criteria logic using electronic sensors and controllers relies on auxiliary power supplies and signal chains.

[0005] Therefore, a power distribution cabinet structure is needed that does not rely on an external control power supply, can perform mechanical logic AND operations on differential pressure direction, pressure rise rate and absolute pressure, and uses the actual position of the anti-backflow door as the permission for the main pressure relief door to release. Summary of the Invention

[0006] Technical problems to be solved

[0007] This invention aims to solve the problems that a single pressure criterion cannot simultaneously take into account rapid action and resistance to false triggering, that back pressure in the channel may cause crossflow in non-faulty compartments, and that the linkage door only allows main pressure relief according to the preset stroke rather than the actual position.

[0008] Technical solution

[0009] To solve the above-mentioned technical problems, the present invention adopts the overall structure defined in claim 1. The direction discrimination element outputs only when the pressure in the corresponding compartment forms a positive pressure difference relative to the common channel; the rate discrimination element utilizes the flow resistance difference between the same pressure tap and the two sampling chambers to convert the pressurization rate into a diaphragm displacement with a limited duration; the absolute pressure discrimination element eliminates pressure disturbances that are only sharp but have insufficient amplitude. The three outputs jointly control the mechanical AND gate; the linkage slider cannot be released if any input is missing.

[0010] Preferably, the mechanism and door are jointly secured by three locking pins to the same release spindle. The locking pins of the rate discrimination element automatically reset after the pressure in the two sampling chambers is equalized, ensuring that the directional input and absolute pressure input arrive within the time window defined by the damping orifice. This structure performs logical operations using geometric constraints, eliminating the need for sensors, controllers, or electromagnetic actuators.

[0011] Preferably, the linkage slider first pushes the anti-backflow door into the reverse stop position, but the anti-backflow door still retains a one-way opening stroke in the direction of pressure relief. The permission pin connected to the anti-backflow door only disengages from the locking groove of the main pressure relief door when the door body is actually in place, after which the linkage slider can continue its stroke and open the main pressure relief door.

[0012] Preferably, a bent flow guide cavity, a metal arc-splitting grid, and a particle trapping filter element are arranged downstream of the main pressure relief valve. The metal arc-splitting grid divides the continuous arc column and absorbs some of the heat, while the staggered perforated plate traps molten particles and increases the creepage path; the expansion sealing strip around the anti-backflow valve seals the assembly gap after being heated.

[0013] Beneficial effects

[0014] (1) Use the pressure difference direction, pressure rise rate and absolute pressure as release conditions at the same time to reduce the probability of malfunction caused by rapid door closing, fan pulsation, maintenance inflation and back pressure in the channel;

[0015] (2) The rate discrimination component forms a finite time window on its own, so that the three aerodynamic criteria must have the time correlation corresponding to the internal arc event;

[0016] (3) The actual position of the anti-backflow door, rather than the theoretical stroke of the linkage slider, constitutes the mechanical permission of the main pressure relief door, reducing the risk of penetration caused by tolerance, jamming and rebound;

[0017] (4) All judgment and permission actions are completed by pressure and elastic potential energy, and can still be operated when the auxiliary power is interrupted;

[0018] (5) The module can be replaced in a drawer-type manner, and the latches, filter elements and seals after operation are easy to inspect and maintain;

[0019] (6) The overall structure is mechanical and pneumatic, and it can be used in parallel with the electrical protection system of existing high-voltage, medium-voltage or low-voltage cabinets without changing the main circuit topology. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the power distribution cabinet of the present invention;

[0021] Figure 2 This is a schematic diagram of the overall structure of the selective pressure relief module;

[0022] Figure 3 This is a schematic diagram showing the selective pressure relief module in normal ventilation mode.

[0023] Figure 4 A schematic diagram showing the selective pressure relief module in a fault-relief state;

[0024] Figure 5 This is a schematic diagram illustrating the selective action of faulty and non-faulty compartments in a shared pressure relief channel.

[0025] Figure 6 This is a schematic diagram of the modular assembly and reset structure of the selective pressure relief module;

[0026] Figure 7 This is a schematic diagram of the principle of a passive three-criteria aerodynamic logic unit;

[0027] Figure 8 A schematic diagram of the pressure rise rate discrimination component;

[0028] Figure 9 Diagram showing the permitting position and main pressure relief valve release sequence to prevent backflow;

[0029] Figure 10 This is a schematic diagram showing the parallel relationship between the normal selective pressure relief path and the overpressure failure safety path.

[0030] Attached reference numerals: 10—Cabinet; 11—Circuit breaker compartment; 12—Busbar compartment; 13—Cable compartment; 14—Instrument compartment; 20, 20a, 20b, 20c—Selective pressure relief module; 21—Differential pressure drive component; 22, 53—Main pressure relief door; 23, 52—Anti-backflow door; 24—Transmission component; 25—Threshold latch; 26—Flame-retardant equalizing branch; 27—Mounting frame; 28—Module box; 29—Particulate filter element; 30—Common pressure relief channel; 31—Safety outlet; 41—Direction discrimination element; 42—Pressure rise rate discrimination element; 421—Rapid sampling chamber; 422—Delayed sampling chamber; 423—Pressure-sensing diaphragm; 424—Damping orifice; 425—Rate output rod; 43—Absolute pressure discrimination element; 44—Mechanical AND gate; 45—Pressure tap; 51—Linked slider; 54—Positioning permission element; 55—Overpressure failure safety path. Detailed Implementation

[0031] Example 1: Cabinet and Selective Pressure Relief System

[0032] like Figure 1 As shown, the cabinet 10 is formed of aluminum-zinc coated steel plate or stainless steel plate with a thickness of 1.5 mm to 3.0 mm, and is divided into a circuit breaker compartment 11, a busbar compartment 12, a cable compartment 13, and an instrument compartment 14 by a metal partition with a grounding connection. The circuit breaker compartment 11, busbar compartment 12, and cable compartment 13 are respectively connected to the common pressure relief channel 30 at the upper rear of the cabinet via selective arc-damping pressure relief modules 20a, 20b, and 20c. The instrument compartment 14 can be independently sealed, or connected to the safety area through a flame-retardant equalizing branch with a smaller cross-section. The common pressure relief channel 30 extends upward to the safety outlet 31, which is opposite to the front operating area.

[0033] Each module 20 has an independent module box 28. The compartment-side opening of the module box 28 communicates with the corresponding compartment, and the passage-side opening communicates with the common pressure relief channel 30. The module box 28 is inserted into the mounting frame 27 along the guide rail and is pressed tightly by wedge-shaped pressure blocks after being inserted to the bottom. The periphery of the mounting frame 27 forms two staggered folded edges, forming a labyrinthine overlapping edge; a stainless steel braided conductive pad is sandwiched between the folded edges to keep the module box 28 and the cabinet 10 at the same potential.

[0034] Example 2: Direction Determination Component

[0035] like Figure 7As shown, the direction discrimination element 41 uses a metal corrugated diaphragm or differential pressure piston with a diameter of 60 mm to 140 mm. Its first pressure-receiving surface is connected to the corresponding electrical compartment through a short pressure tap, and its second pressure-receiving surface is connected to the common pressure relief channel 30 through another short pressure tap. A direction output rod is set at the center of the diaphragm, and the direction output rod drives the first locking pin of the mechanical door 44 through a ratchet-type one-way output claw; when the diaphragm moves in the opposite direction, the one-way output claw slides past the first locking pin during its idle stroke. The directional pressure differential threshold can be set to 0.5 kPa to 5 kPa by a return spring.

[0036] When the pressure in this compartment is increased first, the first pressure-bearing surface undergoes a first mechanical displacement; when the pressure wave reaches the non-faulty compartment module from the common pressure relief channel 30, the second pressure-bearing surface is pressured first, and the directional output rod moves in the opposite direction, preventing the first locking pin from being removed. This structure prevents the main pressure relief door from being released by the back pressure of the channel itself.

[0037] Example 3: Determination of pressurization rate and absolute pressure

[0038] like Figure 8 As shown, both the rapid sampling chamber 421 and the delayed sampling chamber 422 of the pressure rise rate discrimination element 42 obtain the compartment pressure from the same pressure tap 45. The rapid sampling chamber 421 is connected through a rapid pressure tapping branch with an inner diameter of 4 mm to 12 mm and a length of 10 mm to 80 mm; the delayed sampling chamber 422 is connected through a damping orifice 424 with an equivalent aperture of 0.2 mm to 1.2 mm. The pressure-sensing diaphragm 423 between the two chambers is connected to the rate output rod 425. The equivalent flow area of ​​the rapid branch is 5 to 100 times that of the delayed branch.

[0039] When the compartment pressure changes slowly, the pressures of the two sampling chambers are approximately synchronized, and the displacement of the pressure-sensing diaphragm 423 is insufficient to retract the second locking pin. When the compartment pressure rises rapidly within a few milliseconds to tens of milliseconds, the rapid sampling chamber 421 pressurizes first, while the delayed sampling chamber 422 lags behind due to the damping orifice 424. The transient pressure difference between the two drives the rate output rod 425. Using the product R×C of the damping flow resistance R and the aerodynamic compliance C of the delayed sampling chamber as the equivalent time constant, the discrimination time window can be set from 5 ms to 200 ms by replacing the damping orifice 424 and adjusting the chamber volume.

[0040] The absolute pressure criterion 43 employs a pressure piston, a reference pressure chamber, and an adjustable preload spring. The third locking pin is retracted after the pressure piston reaches the set pressure of 1.5 kPa to 10 kPa on the compartment side. The reference pressure chamber can be slowly equalized with the safe area outside the cabinet via a long damping orifice, ensuring that long-term changes in altitude and meteorological pressure do not affect the set pressure difference. The absolute pressure criterion is used to eliminate short-duration but insufficient-energy mechanical shocks or fan pulsations.

[0041] Example 4: Mechanics and Doors and Finite Time Windows

[0042] The mechanism and door 44 includes a release sleeve, a release spindle, and a first locking pin, a second locking pin, and a third locking pin spaced circumferentially along the release sleeve. The three locking pins are driven by a direction-determining element 41, a rate-determining element 42, and an absolute pressure-determining element 43, respectively. The release spindle is subjected to axial force by a storage spring; it cannot move as long as any locking pin remains inserted in the radial locking hole of the release sleeve. Only when all three locking pins are disengaged does the release spindle push the linkage slider 51.

[0043] The second locking pin is connected to the pressure-reset spring. After the fast sampling chamber 421 and the delayed sampling chamber 422 are evenly pressurized through the damping hole 424, the rate output rod 425 returns to its original position, and the second locking pin is reinserted. Thus, even if the direction discrimination element 41 and the absolute pressure discrimination element 43 reach the threshold at a later time, they cannot be combined with the already disappeared rate input to form a passive time-dependent constraint.

[0044] Example 5: Backflow Prevention Permit

[0045] like Figure 9 As shown, the linkage slider 51 is equipped with an anti-backflow cam section and a pressure relief cam section arranged back and forth along the moving direction. After the mechanical door 44 is released, the first stroke pushes the door hinge of the anti-backflow door 52 into the reverse stop guide groove. When the anti-backflow door 52 reaches the end of the guide groove, the positioning permission piece 54 installed on the door hinge exits the locking groove of the main pressure relief door 53, so that the linkage slider 51 can continue to move and the pressure relief cam section can open the main pressure relief door 53.

[0046] After the anti-backflow door 52 enters the reverse stop position, it does not rigidly seal the forward flow path. Its door hinge can still move 5 mm to 30 mm along the forward opening groove, or the door body can still rotate 10° to 45° in the forward direction, allowing the fault airflow to flow from the compartment to the common pressure relief channel 30; when the pressure on the side of the common pressure relief channel 30 is higher, the door body is pushed against the door seat and the reverse movement is restricted by the stop. An inorganic expansion sealing strip is provided around the door seat, which seals the assembly gap after being heated.

[0047] like Figure 10 As shown, to prevent continuous pressure rise in the compartment when the anti-backflow door 52 fails to close due to foreign objects or mechanical damage, an overpressure failure safety passage 55 is installed in parallel next to the main pressure relief door 53. This passage is sealed with a rupture disc or an emergency pressure relief cover with shear connectors. Its rated opening pressure is higher than the absolute pressure threshold of the normal three-criteria mechanism, but lower than the limit pressure difference allowed by the cabinet structure. This passage only handles abnormal failure conditions and does not replace normal three-criteria selective pressure relief.

[0048] Example 6: Selective Operation and Airflow Handling of Multiple Compartments

[0049] Assume an internal electric arc occurs in busbar compartment 12. Module 20b simultaneously generates a positive pressure differential on the compartment side, a rapid pressure rise transient pressure differential, and an absolute pressure reaching a set value. The three locking pins retract within the judgment time window, releasing the spindle to drive the linkage slider 51. The anti-backflow door 52 first enters the reverse stop position and outputs a clearance, followed by the opening of the main pressure relief door 53. The fault airflow pushes open the forward stroke of the anti-backflow door 52 and enters the common pressure relief channel 30.

[0050] When the pressure wave from the shared pressure relief channel 30 reaches modules 20a and 20c, their direction-determining components 41 undergo opposite displacements. Simultaneously, the rapid sampling chamber 421 and the delayed sampling chamber 422 within the non-faulty compartment do not form a transient pressure difference that satisfies the threshold. Therefore, at least the first and second locking pins remain inserted, and the mechanical door 44 cannot be released. This redundancy differs from a structure that relies solely on the back pressure of the shared channel to close the flap.

[0051] Downstream of the main pressure relief valve 53, a bend guide cavity with at least one 90° turn is provided. The cavity is equipped with metal arc-splitting grids spaced 3 mm to 12 mm apart and two or three layers of alumina ceramic porous plates with staggered perforations to reduce the possibility of continuous arc columns, molten particles, and conductive fumes being ejected in a straight line. The fault gas flow is finally deflected by the baffle plate in the shared pressure relief channel 30 and discharged through the safety outlet 31.

[0052] Example 7: Calibration and Verification Method

[0053] Before mounting, module 20 can be installed on a pneumatic calibration bench with a compartment simulation chamber and a channel simulation chamber. The first operating condition involves slowly pressurizing the compartment simulation chamber to above the absolute pressure threshold, requiring the presence of directional and absolute pressure inputs but insufficient rate input, and the mechanical AND gate 44 does not release. The second operating condition applies a rapid pressure pulse with an amplitude below the absolute pressure threshold, requiring the presence of rate input but the third locking pin does not retract. The third operating condition only rapidly pressurizes the channel simulation chamber, requiring the directional output claw to have no travel. The fourth operating condition causes the compartment simulation chamber to simultaneously reach the directional differential pressure threshold, rate threshold, and absolute pressure threshold within a set time, requiring the mechanical AND gate 44 to release.

[0054] In the fourth operating condition, it should also be confirmed through a high-speed displacement sensor or a transparent observation window that the anti-backflow door 52 arrives at its position earlier than the main pressure relief door 53 begins to open; if the anti-backflow door 52 is artificially prevented from arriving at its position, the arrival permitting device 54 should keep the main pressure relief door 53 locked. The above test conditions and acceptance criteria should be determined through type testing based on the cabinet volume, expected internal arc level, and pressure relief channel impedance, and should not be used as an example in this embodiment to replace product verification.

[0055] After the fault is cleared and the power outage is confirmed, the maintenance personnel remove the activated module 20 and check the three discrimination components, mechanical AND gate 44, backflow prevention gate 52, main pressure relief gate 53, and particulate filter element 29. If mechanical AND gate 44 is not reset, the exposed status indicator remains in the fault position to prevent power from being restored without inspection.

[0056] Example 8: Adaptation Form

[0057] In low-voltage distribution cabinets, modules 20 can be arranged in the horizontal busbar area, vertical busbar area, and functional unit area respectively; in medium- and high-voltage metal-clad switchgear, modules 20 can be arranged on the top of the busbar compartment, circuit breaker truck compartment, and cable compartment respectively; in high- and low-voltage combined cabinets, high-voltage units and low-voltage units can share a pressure relief channel with partitioned baffles, but the module triggering differential pressure and pressure relief cross-sectional area of ​​the two are designed separately.

[0058] The direction discrimination element 41, the pressure sensing diaphragm 423, and the absolute pressure discrimination element 43 can all be corrugated diaphragms, rolling diaphragm pistons, or differential pistons with low-friction sealing rings; the mechanical gate 44, in addition to the three-locking pin release sleeve, can also adopt a structure in which three sequential inserts jointly restrict a release rod, and release output cannot be formed if any criterion is missing.

[0059] The above embodiments are illustrative of the present invention and not intended to limit the invention. Equivalent substitutions made without departing from the passive three-criteria time-related logic and the technical concept of backflow prevention and actual arrival permission as defined in the claims should fall within the protection scope of the present invention.

Claims

1. A partitioned high and low voltage switchgear based on passive three-criteria pneumatic logic, comprising a cabinet, at least two electrical compartments separated by metal partitions, a common pressure relief channel, and selective pressure relief modules respectively disposed between each electrical compartment and the common pressure relief channel, characterized in that: Each selective pressure relief module includes a direction discrimination component, a pressure rise rate discrimination component, an absolute pressure discrimination component, a mechanical AND gate, a linkage slider, an anti-backflow door, and a main pressure relief door. The direction discrimination component includes two opposing pressure-receiving surfaces that are respectively connected to the corresponding electrical compartment and the shared pressure relief channel by air pressure action. When the pressure in the corresponding electrical compartment exceeds the pressure in the shared pressure relief channel by a directional pressure difference threshold, it outputs a first mechanical displacement. The pressure rise rate discrimination component includes a rapid sampling chamber, a delayed sampling chamber, and a pressure-sensing diaphragm separating the two. The rapid sampling chamber is connected to the same pressure tap of the corresponding electrical compartment via a rapid pressure tapping branch. The delayed sampling chamber is connected to the pressure tap via a delayed pressure tapping branch with damping orifices. The pressure rise rate discrimination component outputs a first mechanical displacement when the pressure in the corresponding electrical compartment exceeds the pressure in the shared pressure relief channel by a directional pressure difference threshold. When the transient pressure difference between the sampling chamber and the delayed sampling chamber reaches the rate threshold, a second mechanical displacement is output; when the pressure in the corresponding electrical compartment reaches the absolute pressure threshold, the absolute pressure discrimination element outputs a third mechanical displacement; the mechanical door is configured to release the linkage slider only when the first mechanical displacement, the second mechanical displacement, and the third mechanical displacement exist simultaneously within the discrimination time window determined by the damping orifice; after the linkage slider is released, it first drives the anti-backflow door to the reverse stop position that restricts the flow from the common pressure relief channel to the corresponding electrical compartment; after the anti-backflow door is in position, the locking of the main pressure relief door is released by the position permission element, so that the main pressure relief door opens and forms a pressure relief path from the corresponding electrical compartment to the common pressure relief channel.

2. The compartmented high and low voltage distribution cabinet according to claim 1, characterized in that: The direction discrimination device is a differential pressure diaphragm or differential pressure piston disposed between the pressure chamber on the compartment side and the pressure chamber on the channel side. The differential pressure diaphragm or differential pressure piston is connected to a unidirectional output claw that only allows it to output in the pressure drive direction on the compartment side.

3. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: The equivalent flow area of ​​the fast pressure tapping branch is 5 to 100 times that of the delayed pressure tapping branch, and the static pressure on both sides of the pressure-sensing diaphragm is equalized through the damping orifice after the discrimination time window ends.

4. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: The absolute pressure discrimination element includes a pressure piston, a reference pressure chamber, and an adjustable preload spring. One side of the pressure piston is connected to the corresponding electrical compartment, and the other side is subjected to the combined action of the air pressure in the reference pressure chamber and the adjustable preload spring.

5. The compartmented high and low voltage distribution cabinet according to claim 1, characterized in that: The mechanism and door include a release sleeve, a release spindle, and a first locking pin, a second locking pin, and a third locking pin. The three locking pins are driven by the first mechanical displacement, the second mechanical displacement, and the third mechanical displacement, respectively. When any locking pin is not disengaged, it prevents the release spindle from moving. The second locking pin is also connected to a pressure-reset spring to relock the release spindle after the pressure in the fast sampling chamber and the delayed sampling chamber is equalized.

6. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: The linkage slider is provided with an anti-backflow cam section and a pressure relief cam section that act sequentially; the positioning authorization component includes an authorization pin connected to the anti-backflow door, and the authorization pin only exits the locking groove of the main pressure relief door after the anti-backflow door enters the reverse stop position; the anti-backflow door in the reverse stop position can still move along the forward opening stroke to allow the fault airflow to flow to the common pressure relief channel.

7. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: The anti-backflow door is equipped with an arc-resistant panel, and the periphery of the door seat is equipped with an inorganic flame-retardant sealing strip that expands with heat; downstream of the main pressure relief door is a bent flow guiding cavity, a metal arc-dividing grid, and a particle collection filter element including at least two layers of high-temperature resistant porous plates with staggered pore positions.

8. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: The selective pressure relief module is installed in the mounting frame of the metal partition in a drawer-type structure, with a labyrinthine overlapping edge and a conductive elastic seal between them; the outlet of the common pressure relief channel is located at the top of the cabinet or at the upper rear part away from the operating surface, and the channel is equipped with a baffle plate that changes the direction of the fault airflow at least twice.

9. The partitioned high and low voltage distribution cabinet according to claim 1, characterized in that: An overpressure failure safety passage is also provided between the corresponding electrical compartment and the shared pressure relief channel, which is connected in parallel with the main pressure relief door. The overpressure failure safety passage is closed by a rupture disc or an emergency pressure relief cover with a shear connector. Its opening pressure is higher than the absolute pressure threshold and lower than the limit pressure difference allowed by the cabinet structure, so as to form an emergency pressure relief path that does not pass through the positioning permission when the anti-backflow door is not in place and the compartment pressure continues to rise.

10. A passive three-criteria selective pressure relief module for compartmentalized high and low voltage distribution cabinets, characterized in that: The system includes a module housing and, within the module housing, a direction discrimination element, a pressure rise rate discrimination element, an absolute pressure discrimination element, a mechanical AND gate, a linkage slider, an anti-backflow door, a main pressure relief door, and a positioning authorization element. The direction discrimination element, the pressure rise rate discrimination element, and the absolute pressure discrimination element respectively provide the mechanical AND gate with differential pressure direction input, pressure rise rate input, and absolute pressure input. The mechanical AND gate releases the linkage slider only when all three inputs are simultaneously true within a discrimination time window determined by the pressure rise rate discrimination element. The positioning authorization element causes the main pressure relief door to unlock only after the anti-backflow door reaches the reverse stop position. The module housing has connecting flanges facing the electrical compartment and the common pressure relief channel, respectively.

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