Micro-positive pressure circulating dehumidification cable joint dry protection box and dehumidification method

Abstract

The application discloses a kind of micro-positive pressure circulating dehumidification cable joint dry protection box and dehumidification method, including outer shell, inner shell in outer shell, external module, accommodating cavity is opened in inner shell and is adapted to cable joint, external module can be communicated with accommodating cavity, and make accommodating cavity be in micro-positive pressure.In the application, by setting external module, gas can be introduced into accommodating cavity, when humidity in accommodating cavity exceeds humidity setting value, replace gas in accommodating cavity, filter air by molecular sieve filter, can absorb moisture in air, ensure that the gas replaced into accommodating cavity is dry gas, realize the moisture-proof of cable joint protection box, avoid the erosion of sealing ring in humid environment, by communicating with gas inlet pipeline and regeneration pipeline, molecular sieve filter can be regenerated by heating assembly, without replacing molecular sieve filter, prolong the service life of protection box.

Description

Technical Field

[0001] This invention relates to the field of cable joint protection box technology, and more specifically to a dry cable joint protection box with micro-positive pressure circulating dehumidification and a dehumidification method. Background Technology

[0002] High-voltage cable joints are laid in environments such as cable trenches, underground tunnels, and direct burial outdoors. These environments are characterized by high humidity and large temperature differences between day and night, making them vulnerable points in power transmission systems prone to failure.

[0003] Currently, mainstream dry-type cable joint protection boxes on the market rely solely on sealing rings for passive sealing, and internally use bagged static desiccant for moisture prevention, which has many inherent defects: (1) Static desiccant does not have the ability to be regenerated online. It becomes ineffective after being saturated with water vapor and must be replaced manually. The working conditions in enclosed underground spaces such as cable trenches and tunnels are poor, and the frequent opening of the cover results in a large workload and high labor costs for maintenance. (2) The inside of the box is connected to the outside normal pressure and there is no active pressurization structure. Under the high humidity of the underground environment, water vapor will continue to penetrate into the inside through the assembly gap of the shell and the gap of the sealing ring. After long-term use, the sealing and moisture-proof effect will continue to decline, and there is no way to identify the potential for seal damage in advance. (3) Lacking a continuous blowing duct structure, it relies solely on the desiccant to passively adsorb water vapor. In high humidity environments, condensation is very likely to occur inside the cavity, accelerating the aging of cable insulation and corrosion of metal terminals.

[0004] Although online monitoring technology for cable joint protection boxes has made some progress, it still has significant shortcomings, making it difficult to effectively identify and warn of the precursors to fires and explosions.

[0005] (1) Existing monitoring methods are limited and lack coordination: Traditional fire alarm systems often rely on a single temperature sensor or a standard smoke detector. This configuration only responds when the fault has progressed to the point of producing significant high temperatures or visible smoke, making it a reactive alarm. Although some new-generation products attempt to integrate more sensors, these are often simply stacked together, lacking the ability to deeply fuse and collaboratively analyze multi-source data such as temperature, partial discharge, and characteristic gases. Consequently, they struggle to detect the latent signs of a fire before it occurs, such as "no temperature rise and no smoke." (2) The ability to perceive early fire characteristic signals is severely insufficient: Before insulation failure occurs, cable joints typically undergo insulation degradation processes such as partial discharge (PD). Partial discharge is the most sensitive early indicator of insulation defects and can be effectively monitored using methods such as ultra-high frequency (UHF). However, existing protection boxes generally do not integrate this type of partial discharge monitoring function. Simultaneously, cable insulation materials release characteristic gases such as volatile organic compounds (VOCs) through thermal decomposition in the initial stages of heating. This is also an important early warning signal in the very early stages of a fire, but existing systems also lack effective monitoring of these gases.

[0006] (3) The alarm strategy is simple and easily affected by environmental interference: Traditional temperature measurement methods often rely on a single absolute temperature threshold for judgment, failing to adequately consider the impact of gradual fluctuations in ambient temperature, such as sunlight and day-night cycles. This makes setting alarm thresholds difficult and prone to false alarms or missed alarms when ambient temperature changes drastically. Furthermore, the lack of effective ambient temperature compensation or temperature difference analysis strategies severely impacts the system's reliability and usability. Summary of the Invention

[0007] The technical problem to be solved by this invention is how to improve the sealing performance of cable joint protection boxes and extend their service life.

[0008] This invention solves the above-mentioned technical problems through the following technical means: a dry protection box for cable joints with micro-positive pressure circulating dehumidification, comprising an outer shell, an inner shell located within the outer shell, and an external module. The inner shell has a receiving cavity adapted to the cable joint. The external module can communicate with the receiving cavity, causing the receiving cavity to be under micro-positive pressure. The gas supply end of the external module is connected to the receiving cavity through the receiving cavity input pipe. The receiving cavity is connected to the external environment through the receiving cavity output pipe. Both the receiving cavity input pipe and the receiving cavity output pipe are equipped with one-way valves. The external module has an air inlet pipe, which is equipped with a heating component, a molecular sieve filter located downstream of the heating component, and a solenoid valve located downstream of the molecular sieve filter. The air inlet pipe is connected to the input end of the solenoid valve. The two output ends of the solenoid valve are respectively connected to the regeneration pipe and the receiving cavity input pipe. The heating component is used to regenerate the molecular sieve filter. When the humidity in the receiving cavity exceeds the humidity set value, the gas in the receiving cavity is replaced.

[0009] As a preferred technical solution, the inner shell is equipped with multiple sensors. Based on the data collected by the multiple sensors and the comparison with the set threshold, it is determined whether to replace the gas in the containment cavity or to carry out fire response.

[0010] As a preferred technical solution, a fire extinguishing module is provided on the inner shell, and a passive thermal wire is provided on the cable connector. The passive thermal wire is connected to the fire extinguishing module. Fire handling includes closing the solenoid valve and the check valve. The sensor includes a microparticle smoke sensor. If smoldering microparticle smoke is detected, the fire extinguishing module is activated to extinguish the fire.

[0011] As a preferred technical solution, the sensor also includes a TVOC gas sensor, a temperature rise rate sensor, a UHF partial discharge sensor, and a humidity sensor. The microparticle smoke sensor, TVOC gas sensor, temperature rise rate sensor, UHF partial discharge sensor, and humidity sensor are all fixedly connected to the inner wall of the inner shell through heat insulation pads, and the outer wall of the inner shell is coated with a heat insulation coating.

[0012] As a preferred technical solution, both ends of the outer shell are fixedly connected with sealing caps, the inner shell is sealed and fixed to the cable connector by a sealing ring, and sealing mud is provided between the ends of the outer shell and the ends of the inner shell.

[0013] As a preferred technical solution, the external module includes a housing, and a filter assembly and an air pump are provided on the air intake pipe. The filter assembly is located upstream of the air pump, and the air pump is located upstream of the heating assembly.

[0014] As a preferred technical solution, the bottom of the outer shell is provided with a drain hole, which is connected to a discharge pipe. The inner shell is provided with an inspection port, which is provided with an inspection port end cap. The inner shell is connected to the external environment through the cavity output pipe, which is provided with a discharge and exhaust valve.

[0015] As a preferred technical solution, a gap is left between the outer shell and the inner shell.

[0016] As a preferred technical solution, the microparticle smoke sensor, TVOC gas sensor, temperature rise rate sensor, UHF partial discharge sensor, and humidity sensor are all connected to the power supply in the external module via cables, and the power supply is connected to the photovoltaic module.

[0017] As a preferred technical solution, after the gas in the containment cavity is replaced a set number of times, the air input to the molecular sieve filter in the containment cavity is heated by the heating component.

[0018] This invention also provides a dehumidification method for a cable joint dry protection box with micro-positive pressure circulating dehumidification. The cable joint dry protection box with micro-positive pressure circulating dehumidification has multiple sensors on its inner shell. Based on the data collected by the multiple sensors and compared with a set threshold, it is determined whether to replace the gas in the containment cavity or to take fire-fighting measures. Replacing the gas in the containment cavity includes injecting dry air into the containment cavity through the gas supply end of an external module via the containment cavity input pipeline. Fire-fighting measures include shutting off the gas supply to the external module's gas supply end and sealing all pipelines when any two or more types of sensor parameters simultaneously and stably exceed the standard. If smoldering microparticle smoke is detected simultaneously, a micro non-pressurized perfluorohexanone fire extinguishing module is triggered to spray a cleaning fire extinguishing agent to extinguish the fire.

[0019] The beneficial effects of this invention are as follows: (1) In this invention, by setting an external module, gas can be introduced into the containment cavity. When the humidity in the containment cavity exceeds the set humidity value, the gas in the containment cavity is replaced. The air is filtered by a molecular sieve filter, which can absorb the moisture in the air and ensure that the gas replaced into the containment cavity is dry gas. This achieves moisture protection for the cable joint protection box and avoids the corrosion of the sealing ring by the humid environment. By setting the containment cavity to a slightly positive pressure environment, external air is effectively prevented from entering the containment cavity. By connecting the air inlet pipe to the regeneration pipe, the molecular sieve filter can be regenerated by the heating component. There is no need to replace the molecular sieve filter, which extends the service life of the protection box.

[0020] (2) In this invention, by setting multiple sensors in the inner shell and judging the replacement of gas in the cavity or the handling of fire according to the corresponding threshold, the accuracy of monitoring is improved. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the internal structure of the connector protection box provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the connection structure between the connector protection box and the external module and photovoltaic module provided in an embodiment of the present invention; Reference numerals: 1. Cable connector; 2. Inner shell; 3. Outer shell; 4. Sealing putty; 5. Sealing ring; 6. Sealing cap; 7. Photovoltaic module; 8. Power supply; 9. External module; 21. Thermal insulation gasket; 22. TVOC gas sensor; 23. Temperature rise rate sensor; 24. Microparticle smoke sensor; 25. UHF partial discharge sensor; 26. Humidity sensor; 27. Miniature non-pressurized perfluorohexanone fire extinguishing module; 28. Passive thermal wire; 29. ​​Cable; 31. Outer cable hole; 32. Inner cable hole; 33. Outer conduit hole 34. Inner layer pipe hole; 35. Drain hole; 36. Outer layer pressure relief port; 37. Inner layer pressure relief port; 38. Receiving cavity; 41. Inspection port; 42. Inspection port end cap; 43. Exhaust valve; 44. Receiving cavity output pipe; 45. Discharge pipe; 46. Receiving cavity input pipe; 901. Filter assembly; 902. Air pump; 903. Heating assembly; 904. Molecular sieve filter; 905. Solenoid valve; 906. Receiving cavity input pipe check valve; 907. Regeneration pipe check valve; 908. Regeneration pipe; 909. Inlet pipe. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] See Figure 1A dry-type protection box for cable joints with micro-positive pressure circulating dehumidification includes: an outer shell 3, an inner shell 2, and an external module 9. The inner shell 2 has a receiving cavity 38 adapted to the cable joint 1. In this embodiment, the receiving cavity 38 can accommodate the cable joint 1 and is always under micro-positive pressure. The outer shell 3 and the inner shell 2 are nested together, with the inner shell 2 located inside the outer shell 3. A gap is left between the outer shell 3 and the inner shell 2. The outer shell 3 is used for environmental protection, isolating rainwater, mud, groundwater, ultraviolet rays, and mechanical impact, protecting the inner shell 2, pipelines, and sensors from direct corrosion by outdoor buried or exposed environments. The outer shell 3 is installed in half, and the mating surface of the outer shell 3 is provided with a rubber foam sealing gasket to prevent liquid water and mud from seeping into the interlayer gap. The inner shell 2 is made of metal to ensure the airtightness of the entire receiving cavity 38. In this embodiment, the inner shell 2 has a thickness of 0.8~1.2mm. The ring-shaped support frame is made of thin plate. The outer wall of the inner shell 2 is provided with a microporous polyurethane heat insulation coating to isolate the heat conduction of the outer shell 3 and reduce the temperature difference in the receiving cavity 38. The inner shell 2 is also installed by splicing half of the shell. After splicing, it is fastened with bolts. A sealing groove is opened on the mating surface, and a fluororubber sealing ring is set in the sealing groove. The gas supply end of the external module 9 is connected to the receiving cavity 38. In this embodiment, the gas supply end of the external module 9 is connected to the receiving cavity 38 through the receiving cavity input pipe 46. The receiving cavity 38 is connected to the external environment through the receiving cavity output pipe 44. Both the receiving cavity input pipe 46 and the receiving cavity output pipe 44 are equipped with one-way valves to set the receiving cavity 38 to a slightly positive pressure, which prevents outside air from entering the receiving cavity 38. The one-way valve has a valve opening pressure of 0.1MPa to ensure that the receiving cavity 38 maintains a slightly positive pressure of 0.1MPa.

[0024] See Figure 2 To prevent humid air from entering the containment cavity 38, the external module 9 includes a housing, inside which is provided an air inlet pipe 909. The air inlet pipe 909 is connected to the containment cavity input pipe 46. The air inlet pipe 909 is provided with a filter assembly 901, an air pump 902, a heating assembly 903, a molecular sieve filter 904, and a solenoid valve 905 in sequence. The containment cavity input pipe 46 is partially located inside the housing. The solenoid valve 905 includes one input end and two output ends. The input end can be connected to the two output ends. The input end is connected to the air inlet pipe 909, one output end is connected to the containment cavity input pipe 46, and the other output end is connected to one end of the regeneration pipe 908. A regeneration pipe check valve 907 is connected to the regeneration pipe 908, and the other end of the regeneration pipe 908 is connected to the atmosphere. The filter assembly 901 includes a rainproof and insect-proof air intake cover, a first-stage washable stainless steel coarse filter, and a second-stage passive condensation vapor-water separation chamber, which are sequentially arranged on the inlet pipe 46 of the receiving cavity. It can initially complete the separation of water vapor through swirl, glass fiber condensation and mechanical float ball automatic drainage. The one-way valve on the cavity input pipe 46 is the cavity input pipe one-way valve 906. The cavity input pipe one-way valve 906 is located downstream of the solenoid valve 905. The solenoid valve 905 is electrically connected to the controller of the entire external module 9. The controller controls the solenoid valve 905 to switch between the two output ends. The molecular sieve filter 904 can adsorb moisture in the air, thereby ensuring that the gas entering the cavity 38 is dry gas. At this time, the input end is connected to one output end, that is, the air inlet pipe 909 is connected to the cavity input pipe 46. The cavity input pipe 46 is equipped with a pressure sensor. In this embodiment, the pressure sensor is located inside the housing of the external module 9 and is used to detect the internal pressure of the protective box to provide numerical feedback for maintaining the internal micro-positive pressure. The 904 molecular sieve filter uses 3A type A zeolite-specific dehumidification packing. This molecular sieve has a special pore structure that selectively adsorbs only water molecules, without adsorbing air, nitrogen, or other media. It is perfectly suited for high-pressure, slightly positive-pressure dehumidification scenarios in sealed chambers, with a static water adsorption rate of ≥22%, large moisture absorption capacity, and excellent dehumidification effect. Under the coupling effect of a slightly positive-pressure circulating drying airflow within a constant temperature range of 200-220℃, it can efficiently complete water vapor desorption and reset, with a single regeneration capacity recovery rate of ≥90%, and no significant attenuation even after long-term cyclic use. The maximum temperature tolerance of the molecular sieve is ≤250℃, and the upper limit of equipment temperature control is 260℃, leaving a reasonable safety margin. Long-term low-temperature regeneration does not result in pulverization or lattice failure, demonstrating strong operational stability.

[0025] To prevent the molecular sieve filter 904 from losing its adsorption capacity after becoming saturated, in this embodiment, the molecular sieve filter 904 is regenerated by a heating component 903. During regeneration, the heating component 903 is turned on. The heating component 903 can be a dedicated heat source for molecular sieve regeneration. Through precise zone heating, the low-temperature regeneration of the molecular sieve is stably completed, restoring its moisture absorption capacity and replacing traditional disposable desiccants. The dedicated heat source for molecular sieve regeneration is a commercially available component, which adopts a micro-tubular embedded PTC constant temperature ceramic heating structure and is compatible with Φ4mm standard pre-gas pipeline integrated installation. The device has built-in constant temperature characteristics. Heated air enters molecular sieve filter 904 to desorb the saturated molecular sieve packing particles. At this time, the input end of solenoid valve 905 is connected to the other output end, that is, the air inlet pipe 909 is connected to the outlet pipe 44 of the receiving cavity; the air passing through molecular sieve filter 904 is output to the atmospheric environment. The molecular sieve filter 904 is regenerated by high-temperature desorption using the heating component 903 and can be reused repeatedly. This solves the maintenance pain points of traditional desiccants that require moisture saturation and frequent replacement, and is suitable for the long-term unattended operation of the device.

[0026] Both ends of the outer shell 3 are fixedly connected with sealing caps 6. The inner shell 2 and the cable connector 1 are sealed and fixed by sealing rings 5. Sealing mud 4 is provided between the end of the outer shell 3 and the end of the inner shell 2. See Figure 1 The external module 9 is also equipped with a power supply 8, which is used to supply power to the electrical components in the external module 9. In this embodiment, the power supply 8 is electrically connected to the photovoltaic module 7, which is a low-illuminance high-efficiency monocrystalline silicon micro photovoltaic panel, and the power supply 8 is a battery pack.

[0027] See Figure 1 The outer shell 3 has a drain hole 35 at the bottom, which is connected to the discharge pipe 45. The inner shell 2 has an inspection port 41 with an inspection port end cap 42. The inner shell 2 is connected to the external environment through the cavity output pipe 44, and the cavity output pipe 44 is equipped with a discharge exhaust valve 43. The outer shell 3 has an outer pressure relief port 36, and the inner shell 2 has an inner pressure relief port 37. Both the outer pressure relief port 36 and the inner pressure relief port 37 can communicate with the atmospheric environment. Multiple sensors are installed on the inner wall of the inner shell 2, and these sensors are connected to the inner wall of the inner shell 2 via heat insulation pads 21. In this embodiment, the multiple sensors include a TVOC gas sensor 22, a temperature rise rate sensor 23, a particulate smoke sensor 24, a UHF partial discharge sensor 25, and a humidity sensor 26. The TVOC gas sensor 22, temperature rise rate sensor 23, particulate smoke sensor 24, UHF partial discharge sensor 25, and humidity sensor 26 are electrically connected to a power supply 8 via cables 29. The outer shell 3 and the inner shell 2... The body 2 is provided with an outer cable hole 31 and an inner cable hole 32 adapted to the cable 29. The outer shell 3 and the inner shell 2 are provided with an outer pipe hole 33 and an inner pipe hole 34 adapted to the inlet pipe 46 of the receiving cavity, respectively. The inner shell 2 is provided with a miniature non-pressurized perfluorohexanone fire extinguishing module 27. A passive thermal wire 28 is wound around the cable connector 1. The passive thermal wire 28 is connected to the miniature non-pressurized perfluorohexanone fire extinguishing module 27. The inner shell 2 is made of metal to form a Faraday cage, which isolates the high-frequency electromagnetic interference from external high-voltage cables, frequency converters, and lightning surges, and prevents the UHF partial discharge sensor 25 from false alarm. In this embodiment, the passive thermal wire 28 is wrapped around the outer wall of the sheath of the cable connector 1 3 to 4 times.

[0028] TVOC gas sensor 22 is used to monitor combustible organic gases from the thermal decomposition of cable insulation and sheath, and to monitor the core precursors before an explosion. UHF partial discharge sensor 25 monitors internal arcing, creepage, and insulation breakdown precursors, and monitors the primary cause of electrical fires. Temperature rise rate sensor 23 monitors temperature rise rate > 8℃ / min. If a sudden rise occurs, it can distinguish it from normal ambient temperature fluctuations. Microparticle smoke sensor 24 is used to capture trace amounts of smoldering smoke during the smoldering stage. Cable 29 adopts a grounding method with the cavity suspended and the outside single-point grounding to eliminate ground loop interference.

[0029] When the humidity sensor detects that the humidity is higher than a certain threshold, it determines that the humidity inside the containment cavity 38 is too high and that external dry air needs to be introduced through the external module 9.

[0030] When the temperature rise rate sensor 23 detects that the temperature inside the containment cavity 38 drops by 5°C within one hour, it determines that there may be condensation in the containment cavity 38 and starts purging to discharge the water from the discharge pipe 45 at the bottom of the containment cavity. An exhaust valve 43 is installed at the lowest point of the bottom of the accommodating cavity 38 and is connected to the atmosphere. During purging, gas can be discharged from here. If there is condensed water inside, it will accumulate here. During purging, the water will also be discharged at the same time as the exhaust gas. When the pressure sensor detects that the pressure inside the dry chamber is lower than the threshold, it determines that the micro-positive pressure is insufficient and micro-positive pressure gas supply needs to be activated.

[0031] If repeated air replenishment fails to maintain a slight positive pressure within a short period of time, the seal is deemed to have failed, and a seal failure alarm is sent to the monitoring platform, prompting on-site inspection of the sealing ring and flange.

[0032] When the humidity sensor 26 detects a value exceeding the warning threshold and simultaneously detects a slow drop in pressure, it is determined that there is leakage in the inner lining seal. A level one maintenance alarm for seal failure is then uploaded, prompting on-site inspection of the sealing ring and flange.

[0033] When the number of purging cycles exceeds the set number (the number is determined based on the amount of 904 packing material in the regenerated molecular sieve filter), the molecular sieve regeneration process is initiated.

[0034] Based on data collected from multiple sensors, two types of handling conditions are defined: Level 1 hazard warning and Level 2 smoldering / open flame fire handling. Level 1 Hazard Warning: When only a single sensor parameter consistently exceeds the safety threshold, it is determined to be a potential hazard of cable insulation aging or trace thermal decomposition; the air pump 902 adjusts the slightly positive pressure dry air to replace and dilute trace combustible gases, the fire extinguishing module 27 remains in standby mode, and only uploads low-level maintenance prompts and alarms; when a single temperature rise rate exceeds the standard for a short time, or when only the microparticle smoke detector is abnormal without other parameter evidence, the equipment operating conditions are not adjusted, and only internal data is marked. Level II Fire Response: When any two or more types of sensor parameters simultaneously and stably exceed the standard, it is determined that the cable is severely overheated or has smoldering; the system immediately shuts down the micro air supply pump 902 and closes all air circuits to block the supply of oxygen-containing air; if smoldering microparticles and smoke are detected simultaneously, it is determined that an open flame has been generated inside the cavity, and the controller simultaneously outputs an electrical control signal to trigger the micro non-pressurized perfluorohexanone fire extinguishing module 27 to spray a cleaning fire extinguishing agent to extinguish the fire; the device is equipped with a passive thermal sensitive wire 28 for redundancy, which relies on high temperature to automatically start extinguishing the fire in extreme conditions of power supply and main control failure, eliminating the vulnerability of power failure.

[0035] It should be noted that: In this embodiment, for the data collected by the four types of sensors, namely UHF partial discharge sensor 25, TVOC gas sensor 22, temperature rise rate sensor 23, and microparticle smoke sensor 24, any monitored parameter must continuously and stably exceed the corresponding set threshold for 30 seconds to be determined as a valid abnormal signal. The target humidity of the cavity in steady state is ≤40% RH, and the operating micro-positive pressure is maintained at 0.05~0.1MPa. If the pressure is lower than 0.03MPa, a sealing leakage warning will be triggered simultaneously. The threshold values ​​for the four types of monitoring parameters are as follows: UHF partial discharge sensor 25 warning threshold: partial discharge signal amplitude > 100pC, indicating that the cable has creepage or insulation crack discharge; TVOC gas sensor 22 pyrolysis gas warning threshold: the concentration of combustible organic gas in the cavity is >100ppm, which means that the insulating material is decomposed by heat. Temperature rise rate warning threshold for temperature rise rate sensor 23: temperature rise slope per unit time > 8℃ / min; The microparticle smoke sensor 24 has a microparticle smoke detection warning threshold of >800μg / m³ concentration in the cavity, which identifies carbonized nanoparticle smoke.

[0036] Operating condition: Normal, no abnormalities; All four monitoring parameters were within the threshold range, and the slight positive pressure inside the 38-cell cavity was normal (pressure ≥ 0.03 MPa).

[0037] Operating condition: Level 1 hazard warning; If only UHF partial discharge (>100pC) or only TVOC gas exceeds the standard (>100ppm); suspend the high-temperature regeneration heating of the molecular sieve, start the purging of the containment chamber 38, the cumulative purging airflow time is 30min, increase the micro-positive pressure air replacement flow to dilute the combustible gas, the micro non-pressurized perfluorohexanone fire extinguishing module 27 does not start, and upload the first-level operation and maintenance alarm to the background; the alarm will be automatically lifted when the parameters are restored within 10min.

[0038] If the temperature rise rate only exceeds the standard for a short period of time (>8℃ / min), it is determined that the ambient temperature fluctuates and the dehumidification, regeneration, and gas supply systems are not adjusted, and only the data is recorded in the background. If only microparticle smoke is abnormal (>800μg / m³), it is determined to be dust and moisture interference, and no warning is triggered or the equipment operating conditions are adjusted. Operating condition: Level II fire response; If UHF partial discharge exceeds 100 pC and TVOC gas exceeds 100 ppm simultaneously; or if temperature rise (>8℃ / min) exceeds the standard, or if either UHF partial discharge (>100 pC) or TVOC gas (>100 ppm) exceeds the standard, immediately shut down the air pump 902, close all valves, and completely seal off the oxygen supply; the miniature non-pressurized perfluorohexanone fire extinguishing module 27 should remain on standby.

[0039] Simultaneously, excessive levels of particulate matter (>800 μg / m³), temperature rise (>8℃ / min), UHF partial discharge (>100 pC), and TVOC gas (>100 ppm) were detected. At this point, the gas path was kept completely closed to prevent oxygen deprivation, triggering 27 miniature non-pressurized perfluorohexanone fire extinguishing modules. The liquid agent was atomized and filled the cavity to complete cooling and chain-break fire extinguishing. The entire unit was locked, and the highest-level fire alarm was uploaded. Manual opening and reset were required to restart. Micro-positive pressure circulating dehumidification; If the humidity sensor 26 detects that the humidity is higher than the 50% RH threshold for 5 consecutive minutes, the purging is started. The cumulative purging airflow volume is 2-3 times the volume of the gas in the cavity, and the humid gas is completely replaced. When the temperature rise rate sensor 23 detects a decrease of 5°C in the cavity temperature, the purging is started, and the cumulative purging airflow time is 30 minutes to ensure that there is no obvious condensation of water vapor. If the pressure sensor detects that the pressure inside the dry chamber is below 0.03 MPa for 5 consecutive minutes, a micro-positive pressure air supply is initiated to maintain a micro-positive pressure of 0.1 MPa in the dry chamber. If the pressure cannot be maintained at the micro-positive pressure and drops rapidly immediately after replenishment, a seal failure warning is issued.

[0040] When the humidity sensor 26 detects a RH threshold of >60% for 5 consecutive minutes, and simultaneously detects a slow decrease in pressure, it is determined that there is leakage in the inner lining seal. A level-one maintenance alarm for seal failure is uploaded, prompting on-site inspection of the sealing ring and flange.

[0041] When the number of purging cycles exceeds n (e.g., n=5), initiate one molecular sieve regeneration operation.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dry-type protection box for cable joints with micro-positive pressure circulating dehumidification, characterized in that, The system includes an outer shell, an inner shell located within the outer shell, and an external module. The inner shell has a receiving cavity adapted to a cable connector. The external module can communicate with the receiving cavity, causing the receiving cavity to be under slight positive pressure. The gas supply end of the external module is connected to the receiving cavity through the receiving cavity input pipe. The receiving cavity is connected to the external environment through the receiving cavity output pipe. Both the receiving cavity input pipe and the receiving cavity output pipe are equipped with one-way valves. The external module has an air inlet pipe, which contains a heating component, a molecular sieve filter located downstream of the heating component, and a solenoid valve located downstream of the molecular sieve filter. The air inlet pipe is connected to the input end of the solenoid valve. The two output ends of the solenoid valve are connected to the regeneration pipe and the receiving cavity input pipe, respectively. The heating component is used to regenerate the molecular sieve filter. When the humidity in the receiving cavity exceeds the set humidity value, the gas in the receiving cavity is replaced.

2. The cable joint dry protection box with micro-positive pressure circulating dehumidification according to claim 1, characterized in that, The inner shell is equipped with multiple sensors. Based on the data collected by the multiple sensors and the comparison with the set threshold, it is determined whether to replace the gas in the containment cavity or to take fire control measures.

3. The cable joint dry protection box with micro-positive pressure circulating dehumidification according to claim 2, characterized in that, The inner shell is equipped with a fire extinguishing module, and the cable connector is equipped with a passive thermal wire connected to the fire extinguishing module. Fire handling includes closing the solenoid valve and the check valve. The sensor includes a microparticle smoke sensor. If smoldering microparticle smoke is detected, the fire extinguishing module is activated to extinguish the fire.

4. The cable joint dry protection box with micro-positive pressure circulating dehumidification according to claim 3, characterized in that, The sensors also include a TVOC gas sensor, a temperature rise rate sensor, a UHF partial discharge sensor, and a humidity sensor. The microparticle smoke sensor, TVOC gas sensor, temperature rise rate sensor, UHF partial discharge sensor, and humidity sensor are all fixedly connected to the inner wall of the inner shell through heat insulation pads, and the outer wall of the inner shell is coated with a heat insulation coating.

5. The cable joint dry protection box with micro-positive pressure circulating dehumidification according to claim 1, characterized in that, Both ends of the outer shell are fixedly connected with sealing caps. The inner shell is sealed and fixed to the cable connector by a sealing ring. Sealing mud is provided between the ends of the outer shell and the ends of the inner shell.

6. The cable joint dry protection box with micro-positive pressure circulating dehumidification according to claim 1, characterized in that, The external module includes a housing, and a filter assembly and an air pump are installed on the air intake pipe. The filter assembly is located upstream of the air pump, and the air pump is located upstream of the heating assembly.

7. A dry-type protection box for cable joints with micro-positive pressure circulating dehumidification according to claim 1, characterized in that, The outer shell has a drain hole at the bottom, which is connected to a discharge pipe. The inner shell has an inspection port with an end cap. The inner shell is connected to the external environment through the cavity outlet pipe, which has an exhaust valve.

8. A dry-type protection box for cable joints with micro-positive pressure circulating dehumidification according to claim 1, characterized in that, A gap is left between the outer shell and the inner shell. After the gas in the cavity is replaced a set number of times, the air entering the molecular sieve filter is heated by the heating component through the inlet pipe of the cavity.

9. A dry-type protection box for cable joints with micro-positive pressure circulating dehumidification according to claim 4, characterized in that, The microparticle smoke sensor, TVOC gas sensor, temperature rise rate sensor, UHF partial discharge sensor, and humidity sensor are all connected to the power supply inside the external module via cables, and the power supply is connected to the photovoltaic module.

10. A dehumidification method for a cable joint dry protection box with micro-positive pressure circulating dehumidification, characterized in that, Using the cable connector dry protection box for micro-positive pressure circulating dehumidification as described in any one of claims 1-9, the internal gas replacement in the containment cavity includes injecting dry air into the containment cavity through the gas supply end of the external module and the inlet pipeline of the containment cavity; fire handling includes shutting off the gas supply at the gas supply end of the external module and sealing all pipelines when any two or more types of sensor parameters simultaneously and stably exceed the standard; if smoldering microparticles are detected simultaneously, the micro non-pressurized perfluorohexanone fire extinguishing module is triggered to spray a cleaning fire extinguishing agent to extinguish the fire.

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