Cross-linked polyethylene insulated flame-retardant power cable

Abstract

The invention discloses a cross-linked polyethylene insulated flame-retardant power cable applied to the field of cables, and the cable is provided with a plurality of flame-retardant daughters on each battery cell, so that the cable not only can play a role of a firewall when a fire occurs, but also can release flame-retardant liquid through a self-spraying flame-retardant bag to prevent the fire from spreading along the cable, so that the flame-retardant daughters can play a role of fire protection. In addition, the cable can also monitor the overheating stage of the cable before a fire disaster occurs, an alarm is given at the early stage of overheating, active defense is achieved, the multiple flame-retardant sub-bodies on each battery cell cool the cable through circularly flowing cooling liquid, and after the overheating area is monitored, the multiple flame-retardant sub-bodies are linked to enhance the cooling effect on the overheating area, so that the safety of the cable is improved, and the service life of the cable is prolonged. In addition, after a fire disaster occurs, the cooling liquid and the liquid flame retardant are mixed through the flame-retardant parent body and transmitted to the flame-retardant child body for flame retardance, fire spreading is effectively prevented, and precious time is gained for cutting off a power source.

Description

Technical Field

[0001] This invention relates to the field of cables, and in particular to a cross-linked polyethylene insulated flame-retardant power cable. Background Technology

[0002] Cross-linked polyethylene insulated power cables are power cables that use cross-linked polyethylene (XLPE) as the insulation layer. They are mainly used in fixed laying scenarios of power distribution networks or industrial equipment with a rated power frequency voltage of 0.6 / 1kV and below, covering environments such as overhead, indoor, tunnel, and cable trench. Armored types can be directly buried and withstand mechanical external forces.

[0003] Cables must be constantly protected against fire during operation, as fires can cause enormous losses. Therefore, existing cables emphasize flame-retardant design. For example, a flame-retardant cable with publication number CN107578851B has a dry powder layer and a carbon dioxide gasbag. When the outer layer is broken by the spread of fire, the dry powder and carbon dioxide will play a certain role in extinguishing the fire and preventing its spread, which will facilitate subsequent firefighting work and ensure the safety of the circuit to the greatest extent. It will also prevent short circuits caused by small fires.

[0004] Another flame-retardant composite cable, with publication number CN111524648B, utilizes partitions and compression airbags, providing excellent elastic buffering capabilities. Under extreme pressure, the compression airbags break, causing the cable cores to retract into the protective cavity, preventing shearing and exhibiting excellent shear resistance. Furthermore, in the event of a flame, the flames will break the compression airbags, causing the cable cores to retreat into the protective cavity to avoid the fire source. Simultaneously, the inert gas ejected from inside the compression airbags achieves fire extinguishing. It possesses exceptional flame-retardant properties, effectively preventing the rapid spread of flames and the transmission of flames between cables.

[0005] Existing cables only provide flame retardancy after a fire has started, which is relatively passive. However, cables must undergo a heating phase before ignition. Long-term overload operation of cables causes the conductors to overheat. If heat dissipation is not timely, the continuous high temperature will reduce the insulation performance, causing a short circuit and eventually leading to a fire, especially near the joint. Nine out of ten cable fires occur at the joint, which is the weakest link in the cable line. Existing flame-retardant cables rarely provide early warning before a fire starts and can actively defend against it. Summary of the Invention

[0006] The core of this invention lies in proactively preventing flame retardancy through monitoring and early warning of cable overheating, thus addressing the problem of passive flame retardancy in existing technologies. Simultaneously, firewalls are installed on each battery cell to prevent the spread of flames along the cable.

[0007] To solve the above problems, the present invention adopts the following technical solution.

[0008] A cross-linked polyethylene insulated flame-retardant power cable includes a cable body, which is stripped into multiple cores at the terminals. A flame-retardant mother body is fixedly sleeved on the outside of the cable body, and the flame-retardant mother body includes an overheat warning unit and a fire alarm unit. Multiple flame-retardant sub-body is fixedly sleeved on each core. An annular cavity is opened in the middle inner wall of the flame-retardant sub-body, and a flammable heat-conducting pad is fixedly connected to the opening of the annular cavity. An observation tube is fixedly embedded in the flame-retardant sub-body, and the two ends of the observation tube are flush with the inner and outer surfaces of the flame-retardant sub-body, respectively. A transparent plate and a heat-conducting plate are fixedly connected to the two ends of the observation tube, respectively. A temperature-sensing rod is fixedly connected to the inner wall of the heat-conducting plate, and a movable plate that is slidably connected to the inner wall of the observation tube is fixedly connected to the end of the temperature-sensing rod away from the heat-conducting plate. Multiple symmetrically distributed pressure sensors are installed on the side wall of the movable plate facing the temperature-sensing rod, and a pull rope is fixedly connected between the pressure sensors and the heat-conducting plate. The pressure sensors are signal-connected to the overheat warning unit.

[0009] The inner wall of the flame-retardant matrix has multiple equally spaced, circumferentially distributed arc-shaped cavities, the number of which is equal to the number of battery cells. Each arc-shaped cavity and each annular cavity are saturated with coolant. Two symmetrically distributed micro liquid pumps are installed inside each arc-shaped cavity. The upper and lower ends of the flame-retardant sub-body are connected to liquid pipes, and the two liquid pipes are connected to the two micro liquid pumps through connecting pipes. The two micro liquid pumps form a circulation loop with the multiple liquid pipes on each battery cell through the two connecting pipes. A semiconductor cooling chip is installed inside each arc-shaped cavity, and the heat dissipation surface of the semiconductor cooling chip is located outside the flame-retardant matrix. Multiple equally spaced, circumferentially distributed arc-shaped grooves are opened on both side walls of the flame-retardant sub-body, and a self-spraying flame-retardant bag is fixedly connected inside each arc-shaped groove.

[0010] Furthermore, the flame-retardant sub-body is fixedly connected to the inner wall on both sides of the liquid pipe with guide boxes, and the guide boxes are sealed and slidably connected with sealing plates. The two opposite sealing plates are closed to each other. An electromagnet connected to the overheat warning unit is installed inside the guide box. When the electromagnet is energized, it generates a magnetic force that repels the sealing plates. The sealing plates and the electromagnet are connected by an elastic reset band.

[0011] Optionally, a pressure-sensitive colorimetric ball is fixedly connected to the side wall of the movable plate opposite the transparent plate. The pressure-sensitive colorimetric ball does not contact the transparent plate before the phase change of the temperature sensing rod. The temperature sensing rod includes an overheat sensing section, a medium-heat sensing section, and a low-heat sensing section connected sequentially from bottom to top and of equal length. Heat-conducting strips are embedded inside all three sections. The phase change temperature of the overheat sensing section, the medium-heat sensing section, and the low-heat sensing section gradually decreases. Before the phase change, the three sections are S-shaped, and after the phase change, they are straight-line shaped.

[0012] Furthermore, the pressure-sensitive color-developing sphere is a hemispherical structure with a force-sensitive color-changing film bonded to its surface, and the pressure-sensitive color-developing sphere is made of an elastic material.

[0013] Furthermore, the self-spraying flame-retardant bag includes a reservoir and a flame-retardant liquid filled in the reservoir. The reservoir is also filled with high-pressure flame-retardant gas, and the volume of the high-pressure flame-retardant gas accounts for 30%-50% of the volume of the reservoir.

[0014] Preferably, a pressure sensor is installed on the inner wall of the annular cavity, and the pressure sensor is connected to the fire alarm unit. An isolation membrane is fixedly connected to the inner wall of each arc-shaped cavity, and the isolation membrane separates the arc-shaped cavity into two spaces, an outer space and an inner space. Coolant is filled in the outer space, and liquid flame retardant is filled in the inner cavity. An electro-deformable needle is also fixedly connected to the inner wall of the arc-shaped cavity opposite to the isolation membrane, and the fire alarm unit controls the on and off of the electro-deformable needle through the power control unit.

[0015] Furthermore, the electro-deformable needle is curved when de-energized and straight when energized, and the length of the electro-deformable needle is greater than the distance between the isolation membrane and the arc-shaped cavity.

[0016] Furthermore, a flame-prevention plate is installed at the opening of the arc-shaped groove, and the outer side of the flame-prevention plate is fixedly connected to the outer wall of the arc-shaped groove.

[0017] Compared with the prior art, the advantages of this invention are:

[0018] (1) This solution sets multiple flame-retardant sub-body on each battery cell, which can not only act as a firewall when a fire occurs, but also release flame-retardant liquid through self-spraying flame-retardant bags to prevent the fire from spreading along the cable. It can also monitor the overheating stage of the cable before the fire occurs and issue an alarm in the early stage of overheating to achieve proactive defense. Multiple flame-retardant sub-body on each battery cell is cooled by circulating coolant. After the overheating area is detected, multiple flame-retardant sub-body works together to enhance the cooling effect on the overheating area and effectively delay thermal runaway.

[0019] (2) The temperature sensing rod undergoes a phase change according to different temperature ranges, thereby driving the pressure-sensitive colorimetric ball to transmit the signal of the cell's working status to the outside world. This makes it easier for inspection personnel to intuitively understand the cell's working status so that they can take timely countermeasures. In addition, after a fire occurs, the coolant and liquid flame retardant are mixed and delivered to the flame retardant daughter body through the flame retardant mother body to retard the flame, effectively preventing the fire from spreading and buying valuable time to cut off the power supply. Attached Figure Description

[0020] Figure 1 This is a perspective view of the combination of the flame-retardant matrix and the flame-retardant daughter body of the present invention;

[0021] Figure 2 This is a schematic diagram of the connection between the flame-retardant mother body and the flame-retardant daughter body of the present invention and the cable;

[0022] Figure 3 This is a perspective view of a single flame-retardant sub-body of the present invention;

[0023] Figure 4 This is a side cross-sectional view of the flame-retardant sub-body of the present invention;

[0024] Figure 5 This is a cross-sectional view of the inside of the observation tube of the present invention;

[0025] Figure 6 This is a front cross-sectional view of the temperature sensing rod of the present invention;

[0026] Figure 7 This is a schematic diagram showing the color development of the pressure-sensitive colorimetric sphere and temperature-sensing rod of the present invention at different temperature ranges of the battery cell;

[0027] Figure 8 This is a cross-sectional view of the flame-retardant matrix of the present invention.

[0028] Figure 9 This is a cross-sectional view of the internal structure of the flame-retardant subbody of the present invention;

[0029] Figure 10 This is a diagram showing the state of the flame-prevention plate of the present invention after it catches fire.

[0030] Explanation of the labels in the diagram:

[0031] 1 Flame-retardant mother body, 2 Flame-retardant daughter body, 201 Annular cavity, 3 Flammable heat-conducting pad, 4 Pressure sensor one, 5 Observation tube, 501 Transparent plate, 502 Heat-conducting plate, 6 Temperature sensing rod, 601 Overheat sensing section, 602 Medium heat sensing section, 603 Low heat sensing section, 604 Heat-conducting strip, 7 Moving plate, 8 Pressure-sensitive colorimetric ball, 9 Pressure sensor two, 10 Pull rope, 11 Liquid passage pipe, 12 Connecting pipe, 13 Miniature liquid pump, 14 Coolant, 15 Isolation membrane, 16 Liquid flame retardant, 17 Electrodeformable needle, 18 Guide box, 19 Sealing plate, 20 Electromagnet, 21 Self-spraying flame-retardant bag, 22 Flame anti-spreading plate. Detailed Implementation

[0032] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0033] First implementation method:

[0034] Please see Figure 1 , Figure 2 and Figure 5The cable includes a cable body, which is stripped into multiple cores at the terminals. A flame-retardant mother body 1 is fixedly fitted around the cable body, and the flame-retardant mother body 1 includes an overheat warning unit and a fire alarm unit. Multiple equally spaced flame-retardant sub-body 2s are fixedly fitted onto each core. An annular cavity 201 is formed in the inner wall of the center of the flame-retardant sub-body 201, and a flammable heat-conducting pad 3 (made of a heat-conducting material that can be ignited; the specific material is selected according to actual needs and is not discussed here) is fixedly connected to the opening of the annular cavity 201. (To be described in more detail), an observation tube 5 is fixedly embedded in the flame-retardant sub-body 2, and both ends of the observation tube 5 are flush with the inner and outer surfaces of the flame-retardant sub-body 2, respectively. A transparent plate 501 and a heat-conducting plate 502 are fixedly connected to both ends of the observation tube 5, respectively. A temperature-sensing rod 6 (made of shape memory alloy, the specific phase change temperature range threshold is set according to actual needs, and will not be described in detail here) is fixedly connected to the inner wall of the heat-conducting plate 502, and the end of the temperature-sensing rod 6 away from the heat-conducting plate 502 is fixedly connected to a part that slides on the inner wall of the observation tube 5. The movable plate 7 has multiple symmetrically distributed pressure sensors 9 (specific models are selected according to actual needs) installed on the side wall of the movable plate 7 facing the temperature sensing rod 6. The pressure sensors 9 are fixedly connected to the heat-conducting plate 502 by a pull rope 10. The pressure sensors 9 are connected to the overheat warning unit. At the joint, multiple flame-retardant sub-body 2 are sleeved on the battery cell as a group. The multiple groups of flame-retardant sub-body 2 are connected to the flame-retardant mother body 1 through the connecting pipe 12. When the cable is working, the heat of the battery cell is transferred to the temperature sensing rod 6 through the heat-conducting plate 502. When the heat reaches the temperature that can deform the temperature sensing rod 6, it indicates that the battery cell is in the overheating stage. At this time, the temperature sensing rod 6 deforms from the initial bent state to a straight state. The deformation of the temperature sensing rod 6 causes the movable plate 7 to move upward until the pull rope 10 is taut. Then the pressure sensor 9 detects the tension value and sends a warning signal to the overheat warning unit. The overheat warning unit then sends a signal to the background management system, thereby realizing early warning of overheating and effectively preventing the battery cell from being in the overheating stage for a long time and causing a fire.

[0035] Please see Figure 3 , Figure 4The inner wall of the flame-retardant mother body 1 has multiple equally spaced, circularly distributed arc-shaped cavities, the number of which is equal to the number of battery cells. Each arc-shaped cavity and each annular cavity 201 is saturated with coolant 14 (the specific composition is selected according to requirements and is not limited here). Each arc-shaped cavity contains two symmetrically distributed micro-liquid pumps 13 (the specific model is selected according to actual needs). Both the upper and lower ends of the flame-retardant sub-body 2 are connected to liquid-passing pipes 11, and the two liquid-passing pipes 11 are connected to the two micro-liquid pumps 13 via connecting pipes 12. The two micro-liquid pumps 13 form a circulation loop with the multiple liquid-passing pipes 11 on each battery cell through the two connecting pipes 12. Each arc-shaped cavity contains a semiconductor cooling chip (the specific model is selected according to actual needs), and the semiconductor cooling chip... The heat dissipation surface of the cooling plate is located on the outside of the flame-retardant mother body 1. Multiple equally spaced arc-shaped grooves are provided on both sides of the flame-retardant sub-body 2. Each arc-shaped groove is fixedly connected to a self-spraying flame-retardant bag 21. When the battery cell is working, the flammable heat-conducting pad 3 absorbs the heat of the battery cell and transfers it to the coolant 14. Two micro liquid pumps 13 are responsible for supplying the coolant 14 to the annular cavity 201 and for pumping the coolant 14 inside the annular cavity 201 back into the flame-retardant mother body 1. This achieves the circulation of the coolant 14 inside the flame-retardant sub-body 2, thereby cooling the battery cell and effectively reducing the working temperature of the cable in a high-temperature working environment. Moreover, when the battery cell overheats, the cooling effect can effectively delay thermal runaway, buy valuable time for staff to take countermeasures, and thus effectively reduce the risk of fire.

[0036] Please see Figure 9 The flame-retardant sub-body 2 is fixedly connected to the inner wall of both sides of the liquid pipe 11 with guide boxes 18, and the guide boxes 18 are slidably connected with sealing plates 19. The two opposite sealing plates 19 are closed to each other. An electromagnet 20 (the specific model is selected according to actual needs) is installed inside the guide box 18 and is connected to the overheat warning unit signal. When the electromagnet 20 is energized, it generates a magnetic force that repels the sealing plates 19. The sealing plates 19 and the electromagnet 20 are connected by an elastic reset band. For the same cell, when overheating does not occur, the coolant 14 circulates inside the multiple flame-retardant sub-body 2. This achieves balanced cooling. When a flame-retardant sub-body 2 detects overheating of its battery cell, the overheat warning unit activates the electromagnets 20 on other flame-retardant sub-body 2s. The magnetic force generated by the electromagnets 20 repels the sealing plates 19, causing the two opposing sealing plates 19 to close, thereby shutting off the liquid flow pipe 11. In this way, only the flame-retardant sub-body 2 in the overheated area circulates the coolant 14, effectively enhancing the cooling effect of the overheated area. After the heat drops, the electromagnets 20 are turned off, the sealing plates 19 are reset, and the liquid flow pipe 11 is reopened. This linkage effectively reduces the risk of thermal runaway.

[0037] The self-spraying flame-retardant bag 21 includes a liquid reservoir and flame-retardant liquid filled in the liquid reservoir (the specific composition is selected according to the requirements and is not limited here). The liquid reservoir is also filled with high-pressure flame-retardant gas (carbon dioxide is preferred, and the specific pressure threshold is set according to actual needs). The volume of the high-pressure flame-retardant gas accounts for 30%-50% of the volume of the liquid reservoir. When a fire occurs, multiple flame-retardant sub-body 2 isolates the battery cell at a distance, which acts as a firewall. The flame-retardant sub-body 2 can prevent the flame from spreading along the battery cell, buy time for cutting off the power. The flame will directly ignite the liquid reservoir. After the liquid reservoir ruptures, the high-pressure flame-retardant gas inside sprays out along with the flame-retardant liquid, thereby playing the role of extinguishing fire and retardant flame.

[0038] Please see Figure 4 , Figure 10 A flame-prevention plate 22 (made of thermodeformable material) is installed at the opening of the arc-shaped groove. The outer side of the flame-prevention plate 22 is fixedly connected to the outer wall of the arc-shaped groove. When the self-spraying flame-retardant bag 21 sprays outward, the flame-retardant liquid will spray randomly due to the lack of guidance, resulting in very little flame-retardant liquid reaching the ignition point and failing to achieve an effective flame-retardant effect. However, by setting the flame-prevention plate 22, the flame-prevention plate 22 deforms and bends when exposed to the heat of the flame, which plays a directional role in the spraying of the self-spraying flame-retardant bag 21. At the same time, the flame-prevention plate 22 can also effectively prevent the flame from spreading to the unburned cable.

[0039] This embodiment not only serves as a firewall in the event of a fire by setting multiple flame-retardant sub-body 2 on each battery cell, but also releases flame-retardant liquid through a self-spraying flame-retardant bag 21 to prevent the fire from spreading along the cable. Furthermore, it can monitor the overheating stage of the cable before a fire occurs and issue an alarm in the early stage of overheating, thus achieving proactive defense. The multiple flame-retardant sub-body 2 on each battery cell are cooled by the circulating coolant 14, and after the overheating area is detected, the multiple flame-retardant sub-body 2 work together to enhance the cooling effect on the overheated area, effectively delaying thermal runaway.

[0040] Second implementation method:

[0041] Based on the first embodiment, this embodiment improves the synergy between the flame-retardant sub-body 2 and the flame-retardant mother body 1, thereby further enhancing the flame-retardant and overheat monitoring effects of the flame-retardant sub-body 2, while keeping the rest the same.

[0042] Please see Figure 5 , Figure 6 and Figure 7A pressure-sensitive color-developing ball 8 is fixedly connected to the side wall of the movable plate 7 opposite to the transparent plate 501. The pressure-sensitive color-developing ball 8 is a hemispherical structure with a mechanochromic film (made of mechanochromic material) bonded to its surface. The pressure-sensitive color-developing ball 8 is made of elastic material and does not contact the transparent plate 501 before the phase change of the temperature-sensing rod 6. The temperature-sensing rod 6 includes an overheat sensing section 601, a medium-heat sensing section 602, and a low-heat sensing section 603 connected sequentially from bottom to top and of equal length. The interiors of the three sections are simultaneously inlaid with... Embedded with heat-conducting strips 604 (all three sections are made of shape memory alloy, and their respective phase transition temperature thresholds are set according to actual needs), the heat-conducting strips 604 play a role in heat transfer, allowing the overheat sensing section 601, medium-heat sensing section 602, and low-heat sensing section 603 to simultaneously absorb heat from the battery cell. The phase transition temperatures of the overheat sensing section 601, medium-heat sensing section 602, and low-heat sensing section 603 gradually decrease. Furthermore, the three sections are S-shaped before the phase transition and become straight-line shaped after the phase transition. When the battery cell is at a low temperature... In the hot state, the low-heat sensing section 603 deforms first. At this time, the pressure-sensitive color-changing ball 8 is pushed upward and pressed onto the transparent plate 501. Under the pressure, the force-induced color-changing film on the pressure-sensitive color-changing ball 8 changes color. The inspector can see the size of the color-changing area of ​​the pressure-sensitive color-changing ball 8 through the transparent plate 501. When the cell is in the medium-heat state, the medium-heat sensing section 602 deforms next. At this time, the pressure-sensitive color-changing ball 8 is pushed upward further, and the contact area between the pressure-sensitive color-changing ball 8 and the transparent plate 501 increases, and the color-changing area also increases. When the cell is in the overheated state, the color-changing area of ​​the pressure-sensitive color-changing ball 8 reaches its maximum. In this way, the inspector can intuitively understand the working status of the cell by observing the size of the color-changing area of ​​the pressure-sensitive color-changing ball 8, so as to take corresponding countermeasures in time. Moreover, for different cells, the working temperature of each cell can be compared according to the size of the color-changing area of ​​the pressure-sensitive color-changing ball 8 on it, so as to deduce which cell has a failure in cooling effect, which is convenient for timely repair.

[0043] Please see Figure 8A pressure sensor 4 (specific model selected according to actual needs) is installed on the inner wall of the annular cavity 201, and the pressure sensor 4 is connected to the fire alarm unit. An isolation membrane 15 (made of easily breakable elastic material) is fixedly connected to the inner wall of each arc-shaped cavity, dividing the arc-shaped cavity into two spaces: an outer space filled with coolant 14 and an inner space filled with liquid flame retardant 16 (specific composition selected according to needs, not specified here). An electrodeformable needle 17 (made of electrodeformable material) is also fixedly connected to the inner wall of the arc-shaped cavity opposite the isolation membrane 15. The fire alarm unit controls the on / off state of the electrodeformable needle 17 through the power control unit. The electrodeformable needle 17 is in a bent shape when de-energized. When energized, the electrodeformable needle 17 is in a straight line shape, and the length of the electrodeformable needle 17 is greater than the distance between the isolation membrane 15 and the arc-shaped cavity. When a fire occurs, the flame will ignite the flammable heat-conducting pad 3. After the flammable heat-conducting pad 3 breaks, the coolant 14 is released to extinguish the fire. At this time, due to the breakage of the flammable heat-conducting pad 3, the hydraulic pressure inside the annular cavity drops instantly. After the pressure sensor 4 detects this pressure change, it immediately triggers the fire alarm unit. The fire alarm unit sends an alarm signal to the background management system on the one hand, and supplies power to the electrodeformable needle 17 through the power control unit on the other hand. After the electrodeformable needle 17 is energized, it deforms and punctures the isolation membrane 15. The liquid flame retardant 16 mixes with the coolant 14 and is delivered to the flame retardant sub-body 2 by the micro liquid pump 13, thereby extinguishing the fire at the ignition point.

[0044] This embodiment also allows the temperature sensing rod 6 to undergo phase change according to different temperature ranges, thereby driving the pressure-sensitive colorimetric ball 8 to transmit signals of the cell's working status to the outside world. This makes it easier for inspection personnel to intuitively understand the cell's working status and take timely countermeasures. In addition, after a fire occurs, the coolant 14 and liquid flame retardant 16 are mixed and delivered to the flame retardant daughter body 2 through the flame retardant mother body 1 to retard the flame, effectively preventing the fire from spreading and buying valuable time to cut off the power supply.

[0045] The above description is merely a preferred embodiment of the present invention; it encompasses all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A crosslinked polyethylene insulated, flame-retardant power cable comprising a cable body, and the cable body is stripped at a terminal end into a plurality of electrical cores, characterized in that: The outer fixed sleeve of the cable body has a flame-retardant matrix (1), and the flame-retardant matrix (1) comprises an overheating early warning unit and a fire alarm unit, each of the electric cores is fixedly sleeved with a plurality of flame-retardant sub-matrices (2) distributed at equal intervals, the middle inner wall of the flame-retardant sub-matrix (2) is provided with an annular cavity (201), and the opening of the annular cavity (201) is fixedly connected with a flammable heat-conducting pad (3); the flame-retardant sub-matrix (2) is fixedly embedded with an observation cylinder (5), and the two ends of the observation cylinder (5) are flush with the inner and outer surfaces of the flame-retardant sub-matrix (2); the two ends of the observation cylinder (5) are fixedly connected with a transparent plate (501) and a heat-conducting plate (502), respectively; the inner wall of the heat-conducting plate (502) is fixedly connected with a temperature sensing rod (6), and the end of the temperature sensing rod (6) away from the heat-conducting plate (502) is fixedly connected with a moving plate (7) which is in sliding connection with the inner wall of the observation cylinder (5); a plurality of symmetrically distributed pressure sensors two (9) are mounted on the side wall of the moving plate (7) opposite to the temperature sensing rod (6), and a pull rope (10) is fixedly connected between the pressure sensor two (9) and the heat-conducting plate (502); the pressure sensor two (9) is in signal connection with the overheating early warning unit; The inner wall of the flame-retardant matrix (1) is provided with a plurality of arc cavities distributed at equal intervals, and the number of the arc cavities is equal to the number of the electric cores; the inside of each arc cavity and the inside of each annular cavity (201) are saturatedly filled with a cooling liquid (14), and each arc cavity is provided with two symmetrically distributed micro liquid pumps (13); the upper and lower ends of the flame-retardant sub-matrix (2) are communicated with liquid passing pipes (11), and the two liquid passing pipes (11) and the two micro liquid pumps (13) are communicated through communication pipes (12), respectively; the two micro liquid pumps (13) and the plurality of liquid passing pipes (11) on each electric core form a circulation loop through the two communication pipes (12); each arc cavity is provided with a semiconductor refrigeration sheet, and the heat dissipation surface of the semiconductor refrigeration sheet is located outside the flame-retardant matrix (1); the two side walls of the flame-retardant sub-matrix (2) are provided with a plurality of arc grooves distributed at equal intervals, and each arc groove is fixedly connected with a self-spraying flame-retardant bag (21).

2. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 1, characterized in that: The inner walls of the flame-retardant sub-matrix (2) on both sides of the liquid passing pipe (11) are fixedly connected with guide boxes (18), and the inside of the guide box (18) is in sealing sliding connection with a sealing plate (19); the opposite two sealing plates (19) are closed to each other; the inside of the guide box (18) is provided with an electromagnet (20) in signal connection with the overheating early warning unit, and the electromagnet (20) generates a magnetic force repelling the sealing plate (19) in the electrified state; the sealing plate (19) and the electromagnet (20) are connected through an elastic reset belt.

3. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 1, characterized in that: The mobile plate (7) is fixedly connected with a pressure touch color developing ball (8) opposite to the side wall of the transparent plate (501), and the pressure touch color developing ball (8) is not in contact with the transparent plate (501) before the phase change of the temperature sensing rod (6), the temperature sensing rod (6) comprises an overheating sensing section (601), a medium heat sensing section (602) and a low heat sensing section (603) connected in sequence from bottom to top and equal in length, and the three are simultaneously inlaid with heat conducting strips (604) in the inside, the phase change temperatures of the overheating sensing section (601), the medium heat sensing section (602) and the low heat sensing section (603) gradually decrease, and the three are in S shape before phase change and in straight line shape after phase change.

4. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 3, characterized in that: The pressure touch color developing ball (8) is a half-sphere structure with a force-induced color film adhered to the surface, and the pressure touch color developing ball (8) is made of elastic material.

5. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 1, characterized in that: The self-spraying fire-retardant bag (21) comprises a liquid storage bag and fire-retardant liquid filled in the liquid storage bag, and the liquid storage bag is further filled with high-pressure fire-retardant gas, and the volume of the high-pressure fire-retardant gas accounts for 30-50% of the volume of the liquid storage bag.

6. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 1, characterized in that: The inner wall of the annular cavity (201) is provided with a pressure sensor (4), and the pressure sensor (4) is signal connected with the fire alarm unit, the inner wall of each arc-shaped cavity is fixedly connected with an isolation film (15), and the isolation film (15) separates the arc-shaped cavity into two spaces, the outer space is filled with cooling liquid (14), the inner space is filled with liquid fire retardant (16), and the inner wall of the arc-shaped cavity opposite to the isolation film (15) is further fixedly connected with an electrically deformed needle (17), and the electrically deformed needle (17) is controlled by the control unit of the fire alarm unit.

7. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 6, characterized in that: The electrically deformed needle (17) is in a curved shape in the off state, and is in a straight line shape in the on state, and the length of the electrically deformed needle (17) is greater than the distance between the isolation film (15) and the arc-shaped cavity.

8. A crosslinked polyethylene insulated, flame-retardant power cable according to claim 1, characterized in that: The opening of the arc-shaped groove is further provided with a flame prevention plate (22), and the outer side of the flame prevention plate (22) is fixedly connected with the outer side groove wall of the arc-shaped groove.

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