Medium-voltage waterproof cable, preparation method thereof and cable immersion monitoring system

Abstract

The invention discloses a medium-voltage waterproof cable, a preparation method thereof and a cable immersion monitoring system, and belongs to the technical field of cable waterproofing. The preparation method of the medium-voltage waterproof cable comprises the following steps: step S100, manufacturing a cable core; s200, along the axial direction of the medium-voltage waterproof cable, a plurality of immersion sensors are formed between the cable core and a moisture-proof layer, and the moisture-proof layer wraps the periphery of the cable core; and S300, wrapping the periphery of the moisture-proof layer with the sheath layer. Whether the cable is soaked or not can be monitored, the soaking fault position of the cable can be positioned, and an intelligent soaking-proof solution is provided for the cable industry.

Description

Technical Field

[0001] This invention application relates to the technical field of cable waterproofing, and particularly to medium-voltage waterproof cables and their preparation methods, as well as cable immersion monitoring systems. Background Art

[0002] In modern power systems, medium-voltage waterproof cables are widely used in important places such as urban power grids, industrial factory areas, and underground facilities to ensure the stable transmission of medium-voltage power. However, with the increase in cable usage time and changes in the external environment, the risk of cable immersion has increased significantly. Especially in cases such as heavy rain and floods, rising groundwater levels, and pipeline ruptures, the cable may be in a humid environment for a long time, increasing the risk of electrical failures.

[0003] Traditional medium-voltage waterproof cables mainly rely on physical structures to prevent water intrusion, such as waterproof jackets, filling strips, and water-blocking tapes. Although these designs can effectively prevent water from directly entering the cable interior, they do not have the ability to prevent water intrusion caused by external environmental factors. Once the outer waterproof structure of the cable is damaged, aged, or subjected to external impact, water vapor may penetrate into the cable interior, resulting in cable immersion problems. Since the external structural protection no longer works, immersion problems often take a long time to appear. Immersion problems often lead to a decrease in the insulation performance of the cable, thus triggering a series of electrical failures, such as short circuits and leakage risks. These risks not only directly affect the stability of power supply, causing direct economic losses such as power outages and equipment damage, but also may pose safety hazards. For example, after the cable is immersed in water, if a short circuit or leakage occurs, it may lead to a fire accident, seriously threatening the safety of personnel and public property; moreover, the usage environment of the cable is usually variable, including temperature fluctuations, humidity changes, external pressure, etc. Especially extreme weather events such as heavy rain, floods, and rising groundwater levels may cause the cable to be immersed in water for a long time. Traditional cables cannot adapt to these extreme changes, resulting in long-term immersion affecting the cable performance. In such an environment, the water resistance and insulation performance of the cable will also decrease significantly, increasing the probability of electrical failures.

[0004] Traditional medium-voltage waterproof cables also lack effective monitoring and warning mechanisms, especially in places where water immersion problems are likely to occur during long-term use, such as underground cable tunnels or industrial parks. These places have extremely high requirements for the reliability of the power system. The continuous existence of water immersion problems not only leads to frequent cable failures but also may affect the normal operation of the system. The lack of a real-time monitoring system makes it difficult to respond promptly to water immersion problems, increasing the operation and maintenance risks of medium-voltage waterproof cables. Once cable water immersion occurs, it is often difficult to detect it in the early stage. Although there may be warning signs on the outer layer of some cables (such as water immersion alarm devices), the reaction of these alarm devices is usually slow, and they cannot monitor the moisture change inside the cable in real time. Especially when the water vapor inside the cable does not directly cause damage to the insulation layer in the initial stage, there will be no immediate abnormality on the cable surface, resulting in the water immersion problem not being effectively addressed for a long time. Moreover, even when it is known that a water immersion accident has occurred inside the cable, traditional fault location methods often take a long time to determine the location of the fault point. Since the water immersion problem usually manifests as a gradual decrease in the insulation performance of the cable, it is difficult to detect it in time through traditional electrical test equipment in the initial stage, and a large amount of manual inspection and troubleshooting are often required. This traditional fault location method is not only inefficient but may also delay the processing time, leading to more serious fault consequences. Therefore, how to monitor whether the cable is waterlogged, locate the position of the cable water immersion fault, and promptly detect and handle the water immersion fault has become an important technical problem in the field of cable waterproof technology. Summary of the Invention

[0005] The purpose of this application is to provide a medium-voltage waterproof cable, its preparation method, and a cable water immersion monitoring system to partially or fully solve the problems in the existing cable waterproof technology, such as how to prepare the cable, monitor whether the cable is waterlogged, locate the position of the cable water immersion fault, and promptly detect and handle the water immersion fault. To achieve the above purpose, the technical solutions adopted in this application are as follows:

[0006] In the first aspect, a medium-voltage waterproof cable includes: a cable core, a water immersion sensor, a moisture barrier layer, and a sheath layer. The cable core, water immersion sensor, moisture barrier layer, and sheath layer are arranged in sequence from the inside to the outside; along the axial direction of the medium-voltage waterproof cable, multiple water immersion sensors are arranged at intervals. The water immersion sensors are formed between the cable core and the moisture barrier layer. The water immersion sensor includes a sensor body, a first electrode, and a second electrode. The first electrode and the second electrode are connected to the sensor body, and the first electrode and the second electrode are distributed at intervals; the cable core includes multiple wire cores, a filling part, and a wrapping layer. A wrapping layer is arranged outside the filling part; along the cross-sectional direction of the medium-voltage waterproof cable, multiple wire cores are filled in the filling part. The wire core includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, and a metal shielding layer. The conductor, conductor shielding layer, insulating layer, insulating shielding layer, and metal shielding layer are arranged in sequence from the inside to the outside.

[0007] Optionally, the sheath layer includes an armored layer and an outer sheath layer. The outer sheath layer wraps around the outer circumference of the armored layer, and the armored layer wraps around the outer circumference of the moisture barrier layer. The outer sheath layer is formed by extrusion of an environmentally friendly polyethylene material. The nominal thickness of the outer sheath layer is 2.5 mm - 4.9 mm, and the thickness at the thinnest point is not less than 85% of the nominal thickness value of the outer sheath layer - 0.1 mm. The armored layer is formed by helically wrapping metal tapes with a gap. The thickness range of the metal tapes is 0.4 - 0.9 mm, and the gap rate is 40% - 45%. Alternatively, the armored layer is formed by helically wrapping multiple metal wires, and the total gap between the metal wires does not exceed the diameter of one metal wire.

[0008] Optionally, the nominal thickness of the moisture barrier layer is 1.8 mm - 3.5 mm, and the thickness at the thinnest point is not less than 85% of the nominal thickness value of the moisture barrier layer - 0.1 mm. The moisture barrier layer includes an inner sheath layer and an aluminum-plastic composite tape layer. The inner sheath layer is formed by extrusion of an environmentally friendly polyethylene material and is formed on the outer circumference of the aluminum-plastic composite tape layer.

[0009] Optionally, the conductor is a copper conductor, which is formed by stranding bare copper single wires. The diameter range of the bare copper single wires is 2.21 mm - 3.50 mm, and the diameter range of the conductor is 6.0 mm - 34.1 mm. Or, the conductor is an aluminum conductor, which is formed by stranding bare aluminum single wires. The diameter range of the bare aluminum single wires is 2.16 mm - 4.30 mm, and the diameter range of the conductor is 6.0 mm - 34.0 mm.

[0010] Optionally, both the conductor shield layer and the insulation shield layer are made of an environmentally friendly peroxide cross-linked semi-conductive shielding material. The thickness of the conductor shield layer is 0.8 mm. The thickness of the insulation shield layer is 1.0 mm. The insulation layer is made of a cross-linked polyethylene environmentally friendly insulating material. The thickness of the insulation layer is 4.5 mm. The metal shield layer is formed by overlapping helically wrapping soft copper tapes. The thickness of the soft copper tapes is not less than 0.10 mm, the average overlapping rate of the overlapping helical wrapping is not less than 15%, and the minimum overlapping should not be less than 5%.

[0011] Optionally, the cable core includes three cores. The lay ratio range of the cabled core is: the lay ratio is 25 - 35. The wrapping layer is formed by overlapping helically wrapping multiple water-blocking tapes. The thickness of the wrapping layer is 0.3 mm, and the overlapping rate range is 15 - 25%.

[0012] In a second aspect, a method for manufacturing a medium-voltage waterproof cable uses any one of the medium-voltage waterproof cables described in the first aspect above and includes:

[0013] Step S100: Manufacture the cable core;

[0014] Step S200: Along the axial direction of the medium-voltage waterproof cable, multiple immersion sensors are formed between the cable core and the moisture barrier layer, and the moisture barrier layer wraps around the outer circumference of the cable core.

[0015] Step S300: The sheath layer is wrapped around the outer periphery of the moisture barrier layer.

[0016] Optionally, step S100 includes:

[0017] Step S101: Fabricate the core;

[0018] Step S101 includes:

[0019] Step S1011: Fabricate the conductor;

[0020] Step S1012: Fabricate the insulated core, where the insulated core includes a conductor shielding layer, an insulating layer, and an insulation shielding layer, and the conductor, conductor shielding layer, insulating layer, and insulation shielding layer are arranged in sequence from the inside to the outside;

[0021] Step S1013: Place the fabricated insulated core in a drying oven at 60 ± 2 °C for degassing treatment for 120 h, and the starting time is calculated from when the surface temperature of the insulated core reaches 58 °C;

[0022] Step S1014: Wrap the metal shielding layer to fabricate and obtain the core;

[0023] Step S102: Strands of cores and filler materials are stranded to obtain the inner layer of the cable core, and the inner layer of the cable core is overlapped and wrapped with multiple water-blocking tapes to obtain the cable core.

[0024] Optionally, step S200 includes:

[0025] Step S201: Along the axial direction of the medium-voltage waterproof cable, multiple immersion sensors are formed on the outer periphery of the cable core, and an aluminum-plastic composite tape layer covers the outer periphery of the cable core and multiple immersion sensors to obtain a cable core-immersion sensor-aluminum-plastic composite tape layer assembly;

[0026] Step S202: The inner sheath layer is wrapped around the outer periphery of the cable core.

[0027] Optionally, step S201 includes: Take a roll of water immersion sensing tape and place it on the first longitudinal placement bracket. The water immersion sensing tape includes multiple immersion sensors and a take-up tape. The multiple immersion sensors are arranged at intervals on the take-up tape, and unroll the water immersion sensing tape; Take a roll of aluminum-plastic composite tape and place it on the second longitudinal placement bracket, unroll the aluminum-plastic composite tape, align the starting ends of the water immersion sensing tape and the aluminum-plastic composite tape, the aluminum-plastic composite tape layer covers the outer periphery of the cable core and multiple immersion sensors, the aluminum-plastic composite tape covers the water immersion sensing tape, and along the axial direction of the medium-voltage waterproof cable, multiple immersion sensors will be formed on the outer periphery of the cable core to obtain a cable core-immersion sensor-aluminum-plastic composite tape layer assembly;

[0028] Step S202 includes: passing the cable core immersion sensor aluminum-plastic composite tape layer assembly through the extrusion head, and performing an extrusion process on the cable core immersion sensor aluminum-plastic composite tape layer assembly to form an inner sheath layer. The inner sheath layer is obtained by an extrusion process of a sheath material made of environment-friendly polyethylene, and the inner sheath layer wraps around the outer periphery of the cable core.

[0029] Optionally, step S300 includes:

[0030] Step S301: The armor layer wraps around the outer periphery of the moisture barrier layer;

[0031] Step S302: The sheath layer wraps around the outer periphery of the moisture barrier layer to obtain a medium-voltage waterproof cable.

[0032] In a third aspect, a cable immersion monitoring system uses any one of the medium-voltage waterproof cables described in the first aspect above, and includes:

[0033] A power supply module, which is connected to multiple immersion sensors. The multiple immersion sensors monitor the immersion condition of the waterproof medium-voltage cable and obtain the immersion signals of each immersion sensor of the waterproof medium-voltage cable;

[0034] A signal processing module, which is connected to multiple immersion sensors, processes the immersion signals of each immersion sensor of the waterproof medium-voltage cable to obtain the processed immersion electrical signals of each immersion sensor, and sends them to the control module;

[0035] A control module, which receives the processed immersion electrical signals of each immersion sensor, obtains the resistance change of each immersion sensor, and judges whether the resistance change of each immersion sensor reaches a set resistance threshold. If so, the control module controls the alarm module to give an alarm; if not, the cable immersion monitoring system operates normally without giving an alarm.

[0036] The beneficial effects brought by the technical solution provided by this application at least include:

[0037] (1) In the application of the present invention, first, the medium-voltage waterproof cable adopts the method of stranding multiple cores, and the filling material is tightly filled between the cores, effectively enhancing the mechanical strength and compactness of the cable core. The design of the moisture-proof layer and the sheath layer can prevent external moisture from entering, ensuring the stability and waterproof performance of the cable and ensuring the long-term stable operation of the cable. In addition, the medium-voltage waterproof cable is provided with immersion sensors between the cable core and the moisture-proof layer. Based on the conductivity of water, through the first electrode and the second electrode arranged inside the cable, the working principle of water contacting and changing the resistance is used to monitor the immersion situation of the cable, realizing the monitoring of whether the cable is immersed in water, ensuring the safety and reliability of the medium-voltage waterproof cable. In addition, real-time immersion monitoring can also reduce the accumulation of potential hazards caused by cable immersion, reduce the cost of regular inspection and maintenance, extend the service life of the cable, and improve the stability, reliability and economy of cable operation and maintenance. It can be widely applied to various places requiring high-voltage power transmission, such as urban power grids, factories and various high-risk environments, providing an intelligent anti-immersion solution for the cable industry.

[0038] (2) In the application of the present invention, first, through the arrangement of multiple immersion sensors and monitoring through resistance changes, the cable immersion monitoring system can real-time feedback the water immersion situation of the cable, accurately detect the water intrusion point, further locate the specific position where the cable is immersed in water, and can conduct real-time detection and alarm, avoiding the problems of missed detection and lag, greatly reducing the time of manual maintenance and equipment shutdown, reducing the maintenance cost. The provided alarm function helps users take measures in time before the occurrence of faults, reducing the difficulty and frequency of maintenance, ensuring the long-term stable operation of the cable, and thus improving the overall safety and reliability of the power system. In addition, the cable immersion monitoring system can transmit data to the cloud or remote monitoring system for analysis. The intelligent and automated monitoring means enable the power company to always master the health status of the cable, improving the efficiency of cable management and maintenance. It is not only applicable to underground power cables, but also can be widely applied to power distribution systems, industrial parks, power systems in large factories, etc., meeting the requirements of different types of power systems for safe, stable and reliable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings are used to provide a further understanding of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application, and do not constitute a limitation to the present application. In the drawings:

[0040] Figure 1 is a schematic structural diagram of a medium-voltage waterproof cable of the present invention application Figure 1 ;

[0041] Figure 2 is a schematic structural diagram of a medium-voltage waterproof cable of the present invention application Figure 2 ;

[0042] Figure 3 It is a schematic structural diagram of the water immersion sensing tape of the present invention application;

[0043] Figure 4 It is a schematic flow diagram of a method for preparing a medium - voltage waterproof cable of the present invention application;

[0044] Figure 5 It is a schematic flow diagram of the cable immersion monitoring system of the present invention application; Detailed implementation manners

[0045] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention application. However, it is obvious to those skilled in the art that the present invention application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention application, some well - known technical features in the art are not described.

[0046] Exemplary description of medium voltage waterproof cable

[0047] In the first aspect, as Figures 1 to 4 shown, a medium - voltage waterproof cable includes a cable core 100, an immersion sensor 200, a moisture - barrier layer 300, and a sheath layer 400. The cable core 100, the immersion sensor 200, the moisture - barrier layer 300, and the sheath layer 400 are arranged in sequence from the inside to the outside; along the axial direction of the medium - voltage waterproof cable, a plurality of immersion sensors 200 are arranged at intervals. The immersion sensors 200 are formed between the cable core 100 and the moisture - barrier layer 300. The immersion sensor 200 includes a sensor body, a first electrode, and a second electrode. The first electrode and the second electrode are connected to the sensor body, and the first electrode and the second electrode are spaced apart; the cable core 100 includes a plurality of wire cores 101, a filling part 102, and a wrapping layer 103. The wrapping layer 103 is arranged outside the filling part 102; along the cross - sectional direction of the medium - voltage waterproof cable, a plurality of wire cores 101 are filled in the filling part 102. The wire core 101 includes a conductor 1011, a conductor shielding layer 1012, an insulating layer 1013, an insulating shielding layer 1014, and a metal shielding layer 1015. The conductor 1011, the conductor shielding layer 1012, the insulating layer 1013, the insulating shielding layer 1014, and the metal shielding layer 1015 are arranged in sequence from the inside to the outside.

[0048] In some embodiments, the filling part 102 includes a filling material. The filling material and a plurality of wire cores 101 are stranded to obtain the cable core 100. The stranded cable core 100 has an overall circular or approximately circular structure. The plurality of wire cores can be evenly distributed on the cross - section of the cable core, and the filling material can tightly fill the gaps between them, making the structure of the cable core 100 compact and stable.

[0049] In some embodiments, the first electrode 201 and the second electrode 202 are connected to the sensor body 203. The first electrode and the second electrode are spaced apart and in an open state, and the resistance between the first electrode and the second electrode is large. When the medium-voltage waterproof cable is immersed in water, the water can contact the first electrode and the second electrode, connecting the first electrode and the second electrode, resulting in a change in the resistance between the first electrode and the second electrode. The change in resistance can be detected through a circuit. Thus, the first electrode and the second electrode can be connected to the circuit, and the working principle that the conductivity of water causes the first electrode and the second electrode to conduct and then the resistance changes can be utilized. When the cable is immersed in water, the water intervenes between the first electrode and the second electrode, causing the resistance to change, thereby triggering a change in the circuit signal, and further enabling the medium-voltage waterproof cable to have the function of detecting and monitoring immersion in water, thus solving the technical problem of monitoring whether the cable is immersed in water.

[0050] In the present invention application, first, the medium-voltage waterproof cable adopts the method of stranding multiple wire cores, and the filling material is tightly filled between the wire cores, effectively enhancing the mechanical strength and compactness of the cable core. The design of the moisture barrier layer and the sheath layer can prevent external moisture from entering, ensuring the stability and waterproof performance of the cable and ensuring the long-term stable operation of the cable. Additionally, the medium-voltage waterproof cable is provided with an immersion sensor between the cable core and the moisture barrier layer. Based on the conductivity of water, through the first electrode and the second electrode provided inside the cable, the working principle of water contacting and changing the resistance is used to monitor the immersion situation of the cable, realizing the monitoring of whether the cable is immersed in water, and ensuring the safety and reliability of the medium-voltage waterproof cable. Furthermore, real-time immersion monitoring can also reduce the accumulation of potential hazards caused by cable immersion, reduce the costs of regular inspection and maintenance, extend the service life of the cable, and improve the stability, reliability, and economy of cable operation and maintenance. It can be widely applied to various places requiring high-voltage power transmission, such as urban power grids, factories, and various high-risk environments, providing an intelligent anti-immersion solution for the cable industry.

[0051] Optionally, along the axial direction of the medium-voltage waterproof cable, the sensor body is strip-shaped, and the spacing distance range between the first electrode and the second electrode is 50 - 150 mm.

[0052] In some embodiments, along the axial direction of the medium-voltage waterproof cable, the sensor body is strip-shaped and can generally be strip-shaped. Exemplarily, the sensor body is in the shape of a thin continuous strip. The length of the sensor body can be prepared according to the length of the medium-voltage waterproof cable. The width of the sensor body can be 10 mm, and the thickness can be 1.5 mm. The spacing distance between the first electrode and the second electrode ranges from 50 to 150 mm. Preferably, the spacing distance between the first electrode and the second electrode is 100 mm. Of course, those skilled in the art can also reasonably set the length, width, and thickness of the sensor body and the spacing distance between the first electrode and the second electrode according to actual needs. The present invention application does not make special restrictions.

[0053] Optionally, the sheath layer 400 includes an armor layer 402 and an outer sheath layer 401. The outer sheath layer 401 is wrapped around the outer periphery of the armor layer 402, and the armor layer 402 is wrapped around the outer periphery of the moisture barrier layer 300. The outer sheath layer 401 is formed by extrusion of an environmentally friendly polyethylene material. The nominal thickness of the outer sheath layer 401 is 2.5 mm - 4.9 mm, and the thickness of the thinnest point is not less than 85% of the nominal thickness value of the outer sheath layer minus 0.1 mm; the armor layer 402 is formed by overlapping metal tapes with a gap. The thickness range of the metal tape is 0.4 - 0.9 mm, and the gap rate is 40% - 45%; or, the armor layer 402 is formed by winding multiple metal wires, and the total gap between the metal wires does not exceed the diameter of one metal wire.

[0054] In some embodiments, the armor layer 402 is formed by winding multiple metal tapes or multiple metal wires. The thickness range of the metal tape is 0.4 - 0.9 mm, and the total gap between the metal wires does not exceed the diameter of one metal wire, ensuring the density and protection effect of the armor layer 402, and effectively preventing damage to the cable caused by external physical impact, friction, and stretching; at the same time, the nominal thickness of the outer sheath layer 401 is 2.5 mm - 4.9 mm, and the thickness of the thinnest point is not less than 85% of the nominal thickness value of the outer sheath layer 401 minus 0.1 mm (that is, 85% of the nominal thickness value of the outer sheath layer 401 minus 0.1 mm), ensuring that the outer sheath layer can also provide sufficient protection ability. The outer sheath layer 401 is formed by extrusion of an environmentally friendly polyethylene material, and the polyethylene material meets environmental protection requirements, reducing environmental pollution. Thus, through the reasonable structural design of the armor layer 402 and the outer sheath layer 401 of the sheath layer 400, when the cable encounters external impact or abrasion, the sheath layer 400 can provide good physical protection, enabling the cable to have good anti-mechanical damage performance, effectively avoiding interference from external factors to the cable, and ensuring the stability and continuity of power transmission.

[0055] In the application of the present invention, the outer sheath layer 401 is wrapped outside the armor layer 402, and the armor layer 402 is wrapped outside the moisture barrier layer 300. When the cable is exposed to water externally, it can effectively prevent moisture from entering the cable interior, avoid electrical faults caused by the immersion of internal components of the cable, and enhance the waterproof performance of the medium-voltage waterproof cable.

[0056] Optionally, the nominal thickness of the moisture barrier layer 300 is 1.8 mm - 3.5 mm, and the thickness at the thinnest point is not less than 85% - 0.1 mm of the nominal thickness value of the moisture barrier layer; the moisture barrier layer includes an inner sheath layer 302 and an aluminum-plastic composite tape layer 301. The inner sheath layer 302 is formed by extrusion of an environment-friendly polyethylene material and is formed on the outer periphery of the aluminum-plastic composite tape layer 301.

[0057] In some embodiments, the inner sheath layer 302 uses an environment-friendly polyethylene material, which has strong watertightness and corrosion resistance, and can effectively prevent external water sources such as moisture from penetrating into the cable interior. It is particularly suitable for power cables buried underground for a long time or in a humid environment to prevent moisture from damaging the cable.

[0058] In some embodiments, the thickness of the moisture barrier layer is set to 1.8 mm - 3.5 mm, and the thickness at the thinnest point is not less than 85% - 0.1 mm of the nominal thickness value of the moisture barrier layer (that is, 85% of the nominal thickness value of the moisture barrier layer 300 minus 0.1 mm), ensuring that during long-term use, the moisture barrier layer has stable structural strength and will not be damaged or fail due to long-term external pressure or environmental influence.

[0059] In some embodiments, the moisture barrier layer 300 includes a layer of aluminum-plastic composite tape layer 301. Before the inner sheath layer 302 is extruded, a layer of aluminum-plastic composite tape with a thickness of 0.3 mm is longitudinally wrapped. The aluminum-plastic composite tape is usually a material formed by compounding aluminum foil and plastic film through a specific process. The aluminum foil has excellent barrier performance and can almost completely block the penetration of moisture, effectively preventing external moisture from invading the cable interior, enabling the cable to have a waterproof function, avoiding problems such as a decrease in the insulation performance of the cable and conductor corrosion caused by moisture, and ensuring the stable and reliable operation of the cable; at the same time, the aluminum foil is a good electromagnetic shielding material, which can effectively shield external electromagnetic interference and prevent the internal electromagnetic field from interfering with the outside, ensuring the stability and accuracy of power transmission; in addition, the aluminum-plastic composite tape has certain strength and flexibility, which can enhance the compressive and tensile resistance of the cable and prevent damage to the internal structure of the cable due to external forces during cable laying and use; in addition, the plastic film can protect the aluminum foil, reduce the contact between the aluminum foil and external corrosive substances, improve the corrosion resistance of the aluminum-plastic composite tape, and extend the service life of the cable.

[0060] Optionally, the conductor 1011 is a copper conductor, which is composed of stranded bare copper single wires. The diameter range of the bare copper single wires is 2.21 mm - 3.50 mm, and the diameter range of the conductor is 6.0 mm - 34.1 mm; alternatively, the conductor 1011 is an aluminum conductor, which is composed of stranded bare aluminum single wires. The diameter range of the bare aluminum single wires is 2.16 mm - 4.30 mm, and the diameter range of the conductor is 6.0 mm - 34.0 mm.

[0061] In some embodiments, copper has a very high electrical conductivity and is one of the common conductive materials. Copper conductors can provide a very high current-carrying capacity. At the same diameter, the electrical conductivity of copper conductors is better than that of aluminum conductors, so it can effectively reduce power loss. The copper oxide film formed on the copper surface has a certain protective effect, thus extending the service life of the cable. Copper has higher mechanical strength than aluminum, and can provide better tensile strength and anti-deformation ability. Especially under long-term load, copper conductors can better maintain their shape, avoid excessive physical changes, and ensure the stability of the cable. Copper conductors have high stability and are suitable for high-voltage power transmission and precision equipment fields with high current requirements and strict reliability requirements.

[0062] In some embodiments, the density of aluminum is smaller than that of copper. Therefore, aluminum conductors are much lighter than copper conductors and can be used in the laying scenarios of power cables that require long-distance laying, reducing the weight burden of the cables, and lowering the difficulty and cost of transportation and installation. They are suitable for large-scale power transmission and low-voltage lines that are sensitive to costs. Aluminum conductors can be widely used in low-voltage and medium-voltage cables and are suitable for a variety of power and communication applications. In most application scenarios, aluminum conductors can also provide sufficient current-carrying capacity.

[0063] Optionally, both the conductor shield layer 1012 and the insulation shield layer 1014 are composed of environmentally friendly peroxide cross-linked semi-conductive shielding materials; the thickness of the conductor shield layer 1012 is 0.8 mm; the thickness of the insulation shield layer 1014 is 1.0 mm; the insulation layer 1013 is composed of cross-linked polyethylene environmentally friendly insulating materials; the thickness of the insulation layer 1013 is 4.5 mm; the metal shield layer 1015 is composed of overlapping and wound soft copper strips. The thickness of the soft copper strips is not less than 0.10 mm, the average overlapping rate of the overlapping winding is not less than 15%, and the minimum overlap should not be less than 5%.

[0064] In some embodiments, both the conductor shield layer 1012 and the insulation shield layer 1013 use environmentally friendly peroxide cross-linked semi-conductive shielding materials. The 0.8 mm thick conductor shield layer and the 1.0 mm thick insulation shield layer can provide sufficient shielding effectiveness, effectively shielding external electromagnetic, radio frequency and other interferences, and ensuring the long-term stable operation of the cable; at the same time, the peroxide cross-linked semi-conductive shielding materials have good high-temperature resistance, corrosion resistance and wear resistance, can withstand harsh environmental conditions, and extend the service life of the cable.

[0065] In some embodiments, the insulating layer 1013 is made of cross-linked polyethylene environmental protection insulating material with a thickness of 4.5 mm. Cross-linked polyethylene has good electrical insulation performance and high dielectric strength, which can effectively prevent electrical faults inside the cable and ensure power safety. Cross-linked polyethylene can still maintain its insulation performance in high-temperature environments and is especially suitable for high-temperature and high-pressure working environments.

[0066] In some embodiments, the metal shielding layer 1015 is composed of overlapping and lapped soft copper tapes. The soft copper tapes have excellent electrical conductivity. Due to the overlapping and lapping method, the thickness of the soft copper tapes is not less than 0.10 mm, and the lapping rate of the soft copper tapes is not less than 15%, with the minimum lapping rate being 5%. The soft copper tapes can form a stable shielding layer in the cable. The settings of the thickness and lapping rate of the soft copper tapes ensure a high electromagnetic shielding effect, improve the anti-interference ability and electrical safety of the cable. At the same time, the settings of the thickness and lapping rate of the soft copper tapes can enhance the tensile strength of the cable, avoid breakage during laying and use, and enhance the electrical performance, anti-interference ability, mechanical strength and stability of the cable.

[0067] Optionally, the cable core 100 includes three wire cores, and the lay ratio range of the cable core 100 is: the lay ratio is 25 - 35; the wrapping layer 103 is composed of multiple layers of water-blocking tapes overlapping and lapping, with the thickness of the wrapping layer being 0.3 mm and the lapping rate range being 15 - 25%.

[0068] In some embodiments, the cable core 100 includes three wire cores 101, and the three wire cores 101 can be evenly distributed in the cable core, which helps to balance stress, prevent damage to the cable caused by external tension during use, improve the tensile strength and overall stability of the cable, and ensure the stability and efficiency of power transmission.

[0069] In some embodiments, the lay ratio is 25 - 35. A suitable lay ratio can optimize the mechanical performance of the cable, reduce the expansion of the cable, enable the cable to maintain a stable shape when stressed, reduce deformation or breakage of the cable during operation, especially in applications with high tensile strength, ensure that the cable will not affect its use effect due to excessive stretching during construction, and improve the durability of the cable.

[0070] In some embodiments, the wrapping layer 103 is composed of multiple layers of water-blocking tapes overlapping and lapping. The multiple layers of water-blocking tapes can be two layers of water-blocking tapes. The wrapping layer formed by overlapping and lapping two layers of water-blocking tapes can effectively prevent water from entering the cable interior and can also effectively slow down the diffusion rate of water inside the cable. The multiple layers of water-blocking tapes reduce water penetration and enhance the waterproof ability of the cable, enabling the cable to maintain its normal function even in harsh environments (such as rising water levels, pipe ruptures, etc.), and improving the durability and reliability of the cable.

[0071] In some embodiments, the thickness of the wrapping layer is set to 0.3 mm, and the overlapping rate is set within the range of 15%-25%. This can enable the wrapping layer to provide effective protection while reducing the overall weight of the cable, maintaining the flexibility and applicability of the cable. At the same time, a reasonable overlapping rate can not only improve the waterproof performance but also increase the overall mechanical strength of the cable, preventing damage to the cable caused by external forces during use, so that the cable can maintain long-term stable operation in a more complex working environment.

[0072] Exemplary description of preparation method of medium voltage waterproof cable

[0073] Second, the present invention application provides a method for manufacturing a medium-voltage waterproof cable, which uses or does not use any of the medium-voltage waterproof cables described in the first aspect above, and includes:

[0074] Step S100: Manufacture the cable core 100;

[0075] Step S200: Along the axial direction of the medium-voltage waterproof cable, a plurality of water immersion sensors 200 are formed between the cable core 100 and the moisture barrier layer 300, and the moisture barrier layer 300 wraps around the outer periphery of the cable core 100;

[0076] Step S300: The sheath layer 400 wraps around the outer periphery of the moisture barrier layer 300.

[0077] In some embodiments, in step S100, step S100 includes:

[0078] Step S101: Manufacture the wire core 101.

[0079] Specifically, step S101 includes:

[0080] Step S1011: Manufacture the conductor 1011;

[0081] Specifically, step S1011 includes:

[0082] Step S10111: Take a copper rod with a diameter of Φ8 mm and draw it into a bare copper single wire with a diameter of Φ3.33 mm. The tolerance requirement for the bare copper single wire is 3.33±0.01 mm, the elongation rate of the bare copper single wire is ≥37%, and the resistivity of the bare copper single wire does not exceed 0.017241 Ω·mm 2 / m;

[0083] Step S10112: Use a stranding machine to strand the bare copper single wires layer by layer to obtain the conductor 1011:

[0084] The bare copper single wires are arranged in the pattern of 1+6+12+18. From the inner layer to the outer layer, there are 1 bare copper single wire, 6 bare copper single wires, 12 bare copper single wires, and 18 bare copper single wires respectively, divided into four layers and subjected to three times of compacting. Each time of compacting is allocated successively: 6 wire reels, 12 wire reels, and 18 wire reels; Each time of compacting for each layer uses a die with corresponding size and angle for drawing. The lay direction of the bare copper single wires is set as S, Z, S from the inside to the outside. The lay direction of the second outermost layer of bare copper single wires is Z direction, and the lay direction of the outermost layer of bare copper single wires is S direction; The lay length ratio of the outermost layer of bare copper single wires does not exceed 12 times; The requirements for the manufactured conductor 1011 include: The DC resistance of the conductor at 20°C < 0.0601 Ω / km; The weighed cross-sectional area of the conductor is 296.5 mm 2 ; The outer diameter of the conductor is 20.2 ± 0.2 mm.

[0085] Step S1012: Manufacture the insulated wire core. The insulated wire core includes a conductor shielding layer 1012, an insulating layer 1013, and an insulation shielding layer 1014. The conductor 1011, the conductor shielding layer 1012, the insulating layer 1013, and the insulation shielding layer 1014 are arranged successively from the inside to the outside;

[0086] Specifically, step S1012 includes:

[0087] Step S10121: Manufacture the conductor shielding layer 1012. The conductor shielding layer 1012 is obtained by extrusion coating with an environment-friendly peroxide cross-linked semi-conductive shielding material. The nominal thickness of the conductor shielding layer is 0.8 mm; The extrusion coating uses a Φ80 extruder, and the head filter screen has four layers, which are 20 mesh, 120 mesh, 80 mesh, and 20 mesh respectively; The temperatures of the 1st to 8th temperature zones of the extruder are: 80°C, 100°C, 110°C, 112°C, 112°C, 115°C, 116°C, and 118°C respectively. The screw speed of the extruder is 9.4 revolutions per minute, and the extrusion pressure is 440 bar;

[0088] Step S10122: Manufacture the insulating layer 1013. The insulating layer is obtained by extrusion coating with an ultra-clean cross-linked polyethylene material. The nominal thickness of the insulating layer is 10.5 mm; The extrusion coating uses a Φ200 extruder, and the head filter screen has seven layers, which are 20 mesh, 80 mesh, 150 mesh, 300 mesh, 150 mesh, 80 mesh, and 20 mesh respectively. The temperatures of the 1st to 8th temperature zones of the extruder are: 116°C, 118°C, 118°C, 118°C, 118°C, 118°C, 118°C, and 120°C respectively. The screw speed of the extruder is 5.8 revolutions per minute, and the extrusion pressure is 235 bar;

[0089] Step S10123: Produce the insulation shielding layer 1014, which is extruded from an environmentally friendly peroxide cross-linked semi-conductive shielding compound, and the nominal thickness of the insulation shielding layer is 1.0 mm; the extrusion is carried out using a Φ100 extruder, and the head filter screen has four layers, which are 20 mesh, 120 mesh, 80 mesh, and 20 mesh respectively; the temperatures of the 1st to 8th temperature zones of the extruder are: 80 °C, 100 °C, 110 °C, 112 °C, 112 °C, 115 °C, 116 °C, and 118 °C respectively, the screw speed of the extruder is 8.8 revolutions per minute, and the extrusion pressure is 360 bar;

[0090] The conductor shielding layer 1012, the insulation layer 103, and the insulation shielding layer 1014 are extruded using a three-layer co-extrusion, dry cross-linking, and continuous vulcanization production method. The conductor 1011, the conductor shielding layer 1012, the insulation layer 1013, and the insulation shielding layer 1014 are arranged in sequence from the inside to the outside. The catenary curing vehicle (CCV) process is used to obtain the insulated wire core. The die sizes for the three-layer co-extrusion are: die core Φ21.5 mm, Φ23.2 mm, Φ75.0 mm, and die sleeve Φ43.5 mm; the insulated wire core is processed and produced using a catenary cross-linking production line, and the average speed of the production line is 5.6 ± 0.3 m / min.

[0091] In some embodiments, the catenary curing vehicle (CCV) is a cross-linking process commonly used in the production of cable insulation layers. Based on the action of high temperature and cross-linking agents, the cross-linking reaction of the cable insulation material occurs, thereby improving the performance of the cable. The catenary cross-linking process usually includes:

[0092] First, the prepared insulating material can be heated and plasticized by an extruder to make it a melt with good fluidity. Then, under the action of the extruder, the molten insulating material is coated on the conductor to form an insulating layer blank. At this time, the insulating layer blank has not undergone a cross-linking reaction and still has thermoplasticity. Then, the conductor coated with the insulating layer blank enters the cross-linking pipeline in the form of a catenary through a specific suspension device. During the catenary conveying process, the conductor coated with the insulating layer blank is in a freely suspended state, avoiding deformation or damage caused by contact with the support surface, and ensuring the roundness and surface quality of the conductor coated with the insulating layer blank. The inside of the cross-linking pipeline is heated to a relatively high temperature (generally between 200°C and 300°C), and at the same time, an inert gas (such as nitrogen) is introduced. In a high-temperature environment, the cross-linking agent decomposes to generate free radicals, which initiate the activity of polyethylene molecular chains, causing the molecular chains to connect with each other to form a cross-linked structure. Finally, the conductor coated with the insulating layer blank after high-temperature cross-linking leaves the cross-linking pipeline and enters the cooling system. The cooling system usually uses methods such as water spraying or air cooling to cool down, so that the cross-linked insulating layer is shaped and stable physical and chemical properties are obtained. Thus, in the present invention application, the insulated wire core has excellent properties of a cross-linked polyethylene insulating layer, such as high heat resistance, mechanical strength, and electrical insulation performance, etc.

[0093] Step S1013: Place the prepared insulated wire core in a drying oven at 60 ± 2°C for degassing treatment for 120 h, and the starting time is calculated from when the surface temperature of the insulated wire core reaches 58°C.

[0094] Step S1014: Wrap a metal shielding layer to obtain a wire core.

[0095] In some embodiments, Step S1014 includes:

[0096] Use a copper tape with a thickness of 0.10 mm and a width of 40 mm to overlap and wrap around the outer circumference of the insulated wire core processed in Step S1013, and the overlapping rate of the wrapping is 15% - 17%; the outer diameter of the cable after wrapping is 44.0 ± 0.1 mm; during the overlapping wrapping process, control the downward pressure of the tractor so that the cable during the production process is at the same horizontal height, the upward pressure of the tractor is 0.10 - 0.15 MPa, the tensioning pressure is 0.35 - 0.45 MPa, and the take-up tension is 15%, and the take-up tension is 1500 - 3000 N; the copper tape complies with the provisions of GB / T 11091, and the resistivity of the copper tape does not exceed 0.017241 Ω·mm 2 / m.

[0097] Step S102: Strands of multiple wire cores 101 and filler materials are twisted to obtain the inner layer of the cable core, and the inner layer of the cable core is overlapped and wrapped with multiple water-blocking tapes to obtain the cable core 100.

[0098] In some embodiments, step S102 includes:

[0099] Step S1021: Take multiple wire cores prepared in step S101, and twist the multiple wire cores 101 and the filling material to obtain the inner layer of the cable core;

[0100] In step S1021, the inner layer of the cable core includes multiple wire cores 101 and a filling part 102. The cabling direction of the inner layer of the cable core is rightward, the cabling method is untwisting cabling, the cabling pitch diameter ratio ranges from 25 to 35, and the tension setting is not greater than 20 kN; the filling material is non-hygroscopic polypropylene mesh tearing fiber. The requirement for the filling material is that after aging at 100°C ± 2°C for 240 h, no embrittlement phenomenon occurs, and the roundness of the inner layer of the cable core after filling reaches more than 95%.

[0101] Step S1022: The inner layer of the cable core is overlapped and wrapped with multiple water-blocking tapes to obtain the cable core 100.

[0102] In step S1022, the material of the wrapping layer outside the inner layer of the cable core is selected as the water-blocking tape. After overlapping and wrapping with multiple water-blocking tapes, a wrapping layer is obtained. The inner layer of the cable core can obtain the cable core 100 after overlapping and wrapping with multiple water-blocking tapes.

[0103] In some embodiments, the multiple water-blocking tapes can be two water-blocking tapes. The water-blocking tape has a specification of 0.3 mm (thickness) × 80 mm (width), the wrapping overlap width is 12 - 15 mm, and the outer diameter after wrapping can be 95.0 ± 2 mm.

[0104] Optionally, step S200 includes:

[0105] Step S201: Along the axial direction of the medium-voltage waterproof cable, multiple water immersion sensors 200 are formed on the outer periphery of the cable core 100, and an aluminum-plastic composite tape layer 301 covers the outer periphery of the cable core 100 and the multiple water immersion sensors 200 to obtain a cable core water immersion sensor aluminum-plastic composite tape layer assembly;

[0106] In some embodiments, step S201 includes: placing a rolled water immersion sensing tape on the first longitudinal support. The water immersion sensing tape includes a plurality of water immersion sensors 200 and a take-up tape B. The plurality of water immersion sensors are arranged at intervals and installed on the take-up tape. Unroll the water immersion sensing tape; place a rolled aluminum-plastic composite tape on the second longitudinal support, unroll the aluminum-plastic composite tape, align the starting end of the water immersion sensing tape with the starting end of the aluminum-plastic composite tape. The aluminum-plastic composite tape layer 301 covers the outer periphery of the cable core 100 and the plurality of water immersion sensors 200. The aluminum-plastic composite tape covers the water immersion sensing tape. Along the axial direction of the medium-voltage waterproof cable, the plurality of water immersion sensors 200 will be formed on the outer periphery of the cable core 100 to obtain a cable core water immersion sensor aluminum-plastic composite tape layer combination. Exemplarily, after the aluminum-plastic composite tape layer 301 covers the outer periphery of the cable core 100 and the plurality of water immersion sensors 200, the aluminum-plastic composite tape layer 301 wraps and positions or wraps and fixes the plurality of water immersion sensors 200 and / or the take-up tape B. The plurality of water immersion sensors can also be arranged at intervals and installed on the take-up tape. After the take-up tape is wound and taken up, a rolled water immersion sensing tape is formed.

[0107] In some embodiments, the minimum overlap width of the aluminum-plastic composite tape is not less than 5 mm and the width is 330 mm; select appropriate longitudinal wrapping dies and sizing dies according to the outer diameter of the cable core. The dies must be fixedly installed on the die holder. The last sizing die should be assisted by a stainless steel heating coil for heating; adjust the position of the hot air gun to ensure that the surface film of the aluminum-plastic composite tape softens. Check whether the aluminum-plastic composite tape is completely bonded before entering the head.

[0108] Step S202: The inner sheath layer 302 is wrapped around the outer periphery of the cable core 100.

[0109] In some embodiments, step S202 includes: passing the cable core water immersion sensor aluminum-plastic composite tape layer combination through an extrusion head, performing an extrusion process on the cable core water immersion sensor aluminum-plastic composite tape layer combination to form the inner sheath layer 302. The inner sheath layer 302 is obtained by an extrusion process of an environmentally friendly polyethylene sheath material. The inner sheath layer 302 is wrapped around the outer periphery of the cable core 100.

[0110] In some embodiments, the extrusion process includes: taking the sheath material for manufacturing the inner sheath layer 302 and melting it in an extruder to obtain a sheath material melt. The cable core water immersion sensor aluminum-plastic composite tape layer combination passes through the extruder at a certain speed through a traction device. The extruded melt contacts the cable core water immersion sensor aluminum-plastic composite tape layer combination and is coated on its surface to form a continuous coating layer, and is integrally cooled and shaped to obtain the inner sheath layer 302.

[0111] In some embodiments, the nominal thickness of the inner sheath layer 302 is 2.5 mm, meeting the requirements specified in the GB / T 12706 standard. The inner sheath layer has an outer diameter of 101.0 ± 2 mm. The extrusion process uses a Φ150 extruder. The temperatures of the 1st to 9th temperature zones of the extruder are respectively: 148 °C, 175 °C, 178 °C, 177 °C, 176 °C, 175 °C, 176 °C, 181 °C, and 180 °C. The temperatures of the four temperature zones of the head are respectively: 179 °C, 178 °C, 178 °C, and 179 °C. The screw speed of the extruder is 12.0 revolutions per minute, and the extrusion current is 280 A.

[0112] Optionally, step S300 includes:

[0113] Step S301: The armor layer 402 is wrapped around the outer periphery of the moisture barrier layer 300;

[0114] In some embodiments, step S301 includes: The armor layer 402 is wound with double-layer galvanized steel strips with a gap. The thickness is 0.8 mm, the width is 60 mm, and the gap rate is 40% - 45%. The outer diameter after the steel strip winding is 105.0 ± 2 mm. During the winding process, the downward pressure of the tractor is controlled to keep the cable at the same horizontal height during the production process. The upward pressure of the tractor is 0.30 - 0.50 MPa, the tensioning pressure is 1.0 - 1.2 MPa, and the take-up tension is 2500 - 4000 N. The galvanized steel strip complies with the provisions of YB / T 024. The tensile strength of the galvanized steel strip is not less than 295 N / mm 2 , the elongation rate is not less than 20%, and the zinc layer weight of the galvanized steel strip ≥ 40 g / m 2 .

[0115] Step S302: The sheath layer 401 is wrapped around the outer periphery of the moisture barrier layer 300 to obtain a medium-voltage waterproof cable;

[0116] In some embodiments, step S302 includes: The outer sheath layer 401 is obtained by extrusion of an environmentally friendly polyethylene sheath material. The nominal thickness of the outer sheath layer is 4.7 mm, meeting the requirements specified in the GB / T 12706 standard. The overall outer diameter of the obtained medium-voltage waterproof cable is 115.0 ± 2 mm. The extrusion of the sheath material uses a Φ180 extruder. The temperatures of the 1st to 9th temperature zones of the extruder are respectively: 148 °C, 175 °C, 178 °C, 177 °C, 176 °C, 175 °C, 176 °C, 181 °C, and 180 °C. The temperatures of the four temperature zones of the head are respectively: 179 °C, 178 °C, 178 °C, and 179 °C. The screw speed of the extruder is 15.0 revolutions per minute, and the extrusion current is 285 A.

[0117] Exemplary description of cable immersion monitoring system

[0118] In the third aspect, as Figure 5As shown in the figure, the present invention application provides a cable immersion monitoring system, which uses the medium-voltage waterproof cable described in any one of the above first aspects, including:

[0119] A power supply module, which is connected to a plurality of immersion sensors. The plurality of immersion sensors monitor the immersion condition of the waterproof medium-voltage cable and obtain the immersion signals of each immersion sensor of the waterproof medium-voltage cable.

[0120] A signal processing module, which is connected to a plurality of immersion sensors, processes the immersion signals of each immersion sensor of the waterproof medium-voltage cable to obtain the processed immersion electric signals of each immersion sensor, and sends them to the control module.

[0121] A control module, which receives the processed immersion electric signals of each immersion sensor, obtains the resistance change of each immersion sensor, and judges whether the resistance change of each immersion sensor reaches the set resistance threshold. If so, the control module controls the alarm module to give an alarm; if not, the cable immersion monitoring system works normally without giving an alarm.

[0122] In some embodiments, the immersion sensor 200 includes: a sensor body, a first electrode, and a second electrode. The first electrode and the second electrode are connected to the sensor body, and the first electrode and the second electrode are spaced apart. The power supply module can be connected to the first electrode and the second electrode through wires. In a dry environment, the resistance between the first electrode and the second electrode is large. If water enters and contacts the first electrode and the second electrode, due to the strong conductivity of water, the resistance between the first electrode and the second electrode decreases. The power supply module includes one or more power supplies, and the power supply module 10 is connected to a plurality of immersion sensors. The plurality of immersion sensors can monitor the immersion condition of the waterproof medium-voltage cable and obtain the immersion signals of the waterproof medium-voltage cable. The immersion signals of the waterproof medium-voltage cable include the resistance change signals of each immersion sensor.

[0123] In some embodiments, the signal processing module 20 processes the immersion signals of the waterproof medium-voltage cable to obtain immersion electric signals, which is used to convert the resistance change signals of each immersion sensor into the immersion electric signals of each immersion sensor. The immersion electric signals of each immersion sensor can include the immersion voltage of each immersion sensor or the immersion current signal of each immersion sensor. The immersion electric signals of each immersion sensor are amplified, filtered, etc. to obtain the processed immersion electric signals of each immersion sensor. The signal processing module is installed in a control box near the cable laying site, and the control box should have good protection performance to prevent damage to the module caused by the external environment. The signal processing module is connected to the control module of the control center through a communication line, and the communication line method can adopt a wired method or a wireless method.

[0124] In some embodiments, the control module 30 receives the water immersion electrical signals of each processed water immersion sensor, obtains the resistance change of each water immersion sensor, and determines whether the resistance change of each water immersion sensor reaches a set threshold. If so, the control module controls the alarm module 40 to give an alarm; if not, the cable water immersion monitoring system operates normally without giving an alarm. Thus, the control module can preset the set resistance threshold in advance. By monitoring whether the resistance change of each water immersion sensor reaches the set resistance threshold, the control module can determine whether the medium-voltage waterproof cable is waterlogged and can specifically identify which water immersion sensor is waterlogged, so as to determine the water immersion position of the medium-voltage waterproof cable. Moreover, once cable water immersion is detected, the alarm module can immediately send out a warning signal and notify relevant personnel by means of sound and light alarms, text messages, etc., so as to take measures in time to avoid further cable damage or faults.

[0125] In the present invention application, first of all, through the arrangement of multiple water immersion sensors and by monitoring the resistance change, the cable water immersion monitoring system can provide real-time feedback on the water immersion situation of the cable, accurately detect the water intrusion point, further locate the specific position where the cable is waterlogged, and can perform real-time detection and alarm, avoiding the problems of missed detection and lag, greatly reducing the time of manual maintenance and equipment downtime, reducing the maintenance cost. The provided alarm function helps users take measures in time before a fault occurs, reducing the difficulty and frequency of maintenance, ensuring the long-term stable operation of the cable, and thus enhancing the overall safety and reliability of the power system; in addition, the cable water immersion monitoring system can transmit data to the cloud or a remote monitoring system for analysis. The intelligent and automated monitoring means enable the power company to always grasp the health status of the cable, improving the efficiency of cable management and maintenance. It is not only applicable to underground power cables but also widely applicable to power distribution systems, industrial parks, power systems in large factories, etc., meeting the requirements of different types of power systems for safe, stable and reliable operation.

[0126] Those skilled in the art of this technology can understand that the various operations, methods, steps, measures, and solutions in the embodiments discussed in the present invention application can be alternated, changed, combined, or deleted; further, the other steps, measures, and solutions in the various operations, methods, and processes in the embodiments discussed in the present invention application can also be alternated, changed, rearranged, decomposed, combined, or deleted; further, the steps, measures, and solutions in the prior art that are the same as those disclosed in the present invention application can also be alternated, changed, rearranged, decomposed, combined, or deleted. The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the protection scope recorded in the present invention application document.

[0127] The above-described embodiments merely represent several implementation manners of the embodiments of the present disclosure. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the embodiments of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the concept of the embodiments of the present disclosure, several modifications and improvements can still be made, and these all belong to the protection scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the appended claims.

Claims

1. A medium voltage waterproof cable, characterized in that: include: A cable core, a water immersion sensor, a moisture barrier layer, and a sheath layer, which are arranged in sequence from the inside to the outside; along the axial direction of the medium-voltage waterproof cable, a plurality of water immersion sensors are arranged at intervals, the water immersion sensor is formed between the cable core and the moisture barrier layer, the water immersion sensor includes a sensor body, a first electrode, and a second electrode, the first electrode and the second electrode are connected to the sensor body, and the first electrode and the second electrode are distributed at intervals; the cable core includes a plurality of wire cores, a filling part, and a sheath layer, and a sheath layer is arranged outside the filling part; along the cross-sectional direction of the medium-voltage waterproof cable, a plurality of wire cores are filled in the filling part, the wire core includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, and a metal shielding layer, and the conductor, the conductor shielding layer, the insulating layer, the insulating shielding layer, and the metal shielding layer are arranged in sequence from the inside to the outside.

2. A medium voltage waterproof cable according to claim 1, characterized in that: The sheath layer includes an armor layer and an outer sheath layer, the outer sheath layer is wrapped around the outer periphery of the armor layer, the armor layer is wrapped around the outer periphery of the moisture-proof layer, the outer sheath layer is formed by extrusion of an environmentally friendly polyethylene material, the nominal thickness of the outer sheath layer is 2.5mm-4.9mm, and the thickness at the thinnest point is not less than 85%-0.1mm of the nominal thickness value of the outer sheath layer; the armor layer is formed by gap wrapping of a metal belt, the thickness range of the metal belt is 0.4-0.9mm, and the gap rate is 40%-45%; or, the armor layer is formed by wrapping a plurality of metal wires, and the sum of the gaps between the metal wires does not exceed the diameter of one metal wire.

3. A medium voltage waterproof cable according to claim 1, characterized in that: The nominal thickness of the moisture barrier layer is 1.8mm-3.5mm, and the thickness at the thinnest point is not less than 85%-0.1mm of the nominal thickness of the moisture barrier layer; the moisture barrier layer includes an inner sheath layer and an aluminum-plastic composite belt layer, the inner sheath layer is formed by extrusion of an environmentally friendly polyethylene material, and the inner sheath layer is formed on the outer periphery of the aluminum-plastic composite belt layer.

4. A medium voltage waterproof cable according to claim 1, characterized in that: The conductor is a copper conductor, which is composed of bare copper monofilaments twisted together, the diameter of the bare copper monofilaments ranges from 2.21mm to 3.50mm, and the diameter of the conductor ranges from 6.0mm to 34.1mm; or, the conductor is an aluminum conductor, which is composed of bare aluminum monofilaments twisted together, the diameter of the bare aluminum monofilaments ranges from 2.16mm to 4.30mm, and the diameter of the conductor ranges from 6.0mm to 34.0mm.

5. A medium voltage waterproof cable according to claim 1, characterized in that: The conductor shielding layer and the insulating shielding layer are both made of environmentally friendly peroxide cross-linked semi-conductive shielding material; the thickness of the conductor shielding layer is 0.8mm; the thickness of the insulating shielding layer is 1.0mm; the insulating layer is made of cross-linked polyethylene environmentally friendly insulating material; the thickness of the insulating layer is 4.5mm; the metal shielding layer is made of overlapping soft copper tapes, the thickness of the soft copper tapes is not less than 0.10mm, the average overlap rate of overlapping wrapping is not less than 15%, and the minimum overlap should be not less than 5%.

6. A medium voltage waterproof cable according to claim 1, characterized in that: The cable core comprises three wire cores, and the cable core has a cable pitch diameter ratio of 25-35; the wrapping layer is composed of multiple layers of overlapping water-blocking tapes, the thickness of the wrapping layer is 0.3mm, and the overlap rate ranges from 15-25%.

7. A method for preparing a medium-voltage waterproof cable, using a medium-voltage waterproof cable according to any one of claims 1 to 6, characterized in that: include: Step S100: making a cable core; Step S200: along the axial direction of the medium voltage waterproof cable, a plurality of water immersion sensors are formed between the cable core and the moisture barrier layer, and the moisture barrier layer is wrapped around the outer periphery of the cable core; Step S300: The sheath layer is wrapped around the outer periphery of the moisture barrier layer.

8. A method for preparing a medium voltage waterproof cable according to claim 7, characterized in that: Step S100 includes: Step S101: making a wire core; Step S101 includes: Step S1011: making a conductor; Step S1012: manufacturing an insulated wire core, wherein the insulated wire core comprises a conductor shielding layer, an insulating layer, and an insulating shielding layer, wherein the conductor, the conductor shielding layer, the insulating layer, and the insulating shielding layer are sequentially arranged from the inside to the outside; Step S1013: placing the obtained insulated wire core in a 60±2°C drying room for degassing for 120 hours, with the starting time being calculated from when the surface temperature of the insulated wire core reaches 58°C; Step S1014: Wrapping a metal shielding layer to obtain a wire core; Step S102: twisting a plurality of wire cores and filling materials to obtain an inner layer of a cable core, and wrapping the inner layer of the cable core with multiple layers of overlapping water-blocking tape to obtain a cable core.

9. A method for preparing a medium voltage waterproof cable according to claim 8, characterized in that: Step S200 includes: Step S201: along the axial direction of the medium voltage waterproof cable, a plurality of water immersion sensors are formed on the outer periphery of the cable core, and an aluminum-plastic composite tape layer is covered on the cable core and the outer periphery of the plurality of water immersion sensors to obtain a cable core water immersion sensor aluminum-plastic composite tape layer assembly; Step S202: The inner sheath layer is wrapped around the outer circumference of the cable core.

10. A method for preparing a medium voltage waterproof cable according to claim 9, characterized in that: Step S201 comprises: taking a rolled water immersion sensor tape and placing it on a first longitudinal support, the water immersion sensor tape comprising a plurality of water immersion sensors and a winding tape, the plurality of water immersion sensors being arranged at intervals and installed on the winding tape, and rolling out the water immersion sensor tape; taking a rolled aluminum-plastic composite tape and placing it on a second longitudinal support, rolling out the aluminum-plastic composite tape, making the starting end of the water immersion sensor tape correspond to the starting end of the aluminum-plastic composite tape, the aluminum-plastic composite tape layer covering the cable core and the outer periphery of the plurality of water immersion sensors, the aluminum-plastic composite tape covering the water immersion sensor tape, and along the axial direction of the medium-voltage waterproof cable, the plurality of water immersion sensors will be formed on the outer periphery of the cable core to obtain a cable core water immersion sensor aluminum-plastic composite tape layer assembly; Step S202 includes: passing the cable core water immersion sensor aluminum-plastic composite tape layer assembly through an extruder head, and performing an extrusion process on the cable core water immersion sensor aluminum-plastic composite tape layer assembly to form an inner sheath layer, wherein the inner sheath layer is made by an extrusion process of an environmentally friendly polyethylene sheath material, and the inner sheath layer is wrapped around the outer periphery of the cable core.

11. A method for preparing a medium voltage waterproof cable according to claim 10, characterized in that: Step S300 includes: Step S301: The armor layer is wrapped around the outer periphery of the moisture barrier layer; Step S302: The sheath layer is wrapped around the outer periphery of the moisture barrier layer to obtain a medium voltage waterproof cable.

12. A cable water immersion monitoring system, using a medium voltage waterproof cable according to any one of claims 1 to 6, characterized in that: include: A power module, the power module is connected to multiple water immersion sensors, the multiple water immersion sensors monitor the water immersion of the waterproof medium voltage cable, and obtain a water immersion signal of each water immersion sensor of the waterproof medium voltage cable; A signal processing module, the signal processing module is connected to a plurality of water immersion sensors, processes the water immersion signal of each water immersion sensor of the waterproof medium voltage cable to obtain a processed water immersion electrical signal of each water immersion sensor, and sends the processed water immersion electrical signal to the control module; The control module receives the processed water immersion electrical signal of each water immersion sensor, obtains the resistance change of each water immersion sensor, and determines whether the resistance change of each water immersion sensor reaches the set resistance threshold. If yes, the control module controls the alarm module to alarm; if not, the cable water immersion monitoring system works normally and does not alarm.

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