Low-loss medium voltage water-blocking power cable

Abstract

This invention relates to the field of cables, and more particularly to a low-loss, medium-voltage, water-blocking power cable, comprising several conductive cores, each core covered with an insulation layer, the insulation layer covered with an inner sheath, the inner sheath having a water-blocking composite layer, and an outer sheath surrounding the water-blocking composite layer. This invention utilizes a heat dissipation shell, a water-blocking shell, a water-swellable layer, a water inlet channel, and exhaust micropores. After the water-swellable layer absorbs water and expands, it forms a seal through compression to prevent further water diffusion. Simultaneously, the water is introduced into the heat dissipation shell through the water inlet channel. The heat generated by the conductor during normal cable operation vaporizes the water, which then evaporates into the external atmosphere through the exhaust micropores. This achieves active drainage and evaporation of the infiltrated water, avoiding the problem of water remaining on the insulation surface for extended periods, thus preventing increased insulation loss.

Description

Technical Field

[0001] This invention relates to the field of cables, and more particularly to a low-loss, medium-voltage, water-blocking power cable. Background Technology

[0002] When medium-voltage power cables are laid in humid environments or underground, moisture can easily seep into the cable interior radially or axially, causing water treeing aging in the insulation layer and significantly reducing the cable's electrical performance and service life. To prevent moisture intrusion, existing technologies often employ various water-blocking structures, such as filling the conductor gaps with water-blocking powder, water-blocking yarn, or water-blocking tape; wrapping the insulation layer with aluminum-plastic composite tape, lead sheath, or copper tape as a radial water-blocking layer; or installing a water-swellable water-blocking layer. Water-swellable materials (such as water-absorbing swellable rubber or swellable resin) expand in volume upon contact with moisture, compressing and sealing the gaps, thereby preventing further moisture diffusion.

[0003] However, in actual use, the above water-blocking solution still has the following shortcomings: For example, although the water-swellable layer can temporarily block the water inlet channel after absorbing water and expanding, the water that has already seeped into the cable cannot be discharged on its own. If it remains on the surface of the insulation layer or in the structural gaps for a long time, it will continuously induce water tree growth, leading to increased insulation loss and reduced long-term operational reliability of the cable.

[0004] Therefore, this invention proposes a low-loss, medium-voltage water-blocking power cable to solve the above problems. Summary of the Invention

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: a low-loss medium-voltage water-blocking power cable, comprising several conductive cores, wherein the surface of each core is covered with an insulation layer, the surface of the insulation layer is covered with an inner sheath, the surface of the inner sheath is provided with a water-blocking composite layer, and an outer sheath is provided outside the water-blocking composite layer, wherein the water-blocking composite layer comprises: Several heat dissipation shells are linearly arrayed and fixedly connected to the outside of the inner sheath. A water-blocking shell is provided between two adjacent heat dissipation shells. The outer wall of each water-blocking shell is covered with a water-swellable layer. Each water-swellable layer is covered with an outer sheath. Both sides of the heat dissipation shell are provided with several water inlet grooves in a ring array, and the outer wall of the heat dissipation shell is provided with exhaust micropores in a ring array. After the water-expanding layer absorbs water and expands, it is squeezed against the water-blocking shell and the outer sheath. Under the reverse squeezing of the water-blocking shell and the outer sheath, the water in the water-expanding layer enters the heat dissipation shell through the water inlet grooves, is heated by the heat dissipation shell, and evaporates through the exhaust micropores.

[0006] Preferably, the outer wall of the water-blocking shell is provided with a ring array of several slots, and a heat-conducting plate is slidably connected in the several slots, and the heat-conducting plate is connected to the water-expanding layer; The water-blocking shell has a first flow groove symmetrically opened at the position corresponding to the empty slot, and the heat dissipation shell has a second flow groove opened at the position corresponding to the first flow groove, so that airflow can flow. The water-blocking shell has a water inlet trough at the position corresponding to the empty trough, and the drinking water trough is positioned opposite the water inlet trough.

[0007] Preferably, the heat dissipation shell is symmetrically provided with annular baffles at both ends, and the annular baffles abut against the end of the water-swellable layer so that the end of the water-swellable layer does not come into contact with the water inlet tank.

[0008] Preferably, the heat sink shell has symmetrically arranged sealing cavities at both ends, a piston is slidably connected in the sealing cavity, several sliding rods are fixedly connected to the side wall of the piston, several sliding rods are fixedly connected to the corresponding annular baffle, the side wall of the heat sink shell has an air groove communicating with the sealing cavity, and the side of the sealing cavity near the annular baffle is filled with inert gas.

[0009] Preferably, the heat dissipation shell has a ring array of several heat dissipation fins.

[0010] Preferably, capillary channels are symmetrically arranged on the sidewalls of the heat dissipation fins.

[0011] Preferably, the outer wall of the heat dissipation shell is coated with a hydrophobic layer.

[0012] Preferably, the heat-conducting plate is a metal plate.

[0013] Preferably, the heat dissipation shell is provided with a moisture-permeable membrane, which allows water vapor to pass through but prevents liquid water from passing through.

[0014] Preferably, the water-swellable layer is an expandable rubber.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention incorporates a heat dissipation shell, a water-blocking shell, a water-expanding layer, a water inlet groove, and exhaust micropores. After the water-expanding layer absorbs water and expands, it forms a seal through compression to prevent further diffusion of moisture. Simultaneously, the moisture is introduced into the heat dissipation shell through the water inlet groove. The moisture is vaporized by the heat generated by the conductor during normal cable operation and evaporated into the external atmosphere through the exhaust micropores. This achieves the active discharge and evaporation of infiltrated moisture, avoiding the problem of moisture remaining on the surface of the insulation layer for a long time, which increases insulation loss.

[0016] This invention incorporates an empty slot, a heat-conducting plate, a first flow slot, a second flow slot, and a water-guiding slot. During drying, the heat-conducting plate seals the water-guiding slot, while the first and second flow slots are connected to form a micro-circulation of airflow, aiding in cable heat dissipation. When exposed to water, the water-expanding layer pushes the heat-conducting plate downwards, blocking the first flow slot to prevent moisture from entering the inner sheath. Simultaneously, the water-guiding slot opens to guide moisture into the heat dissipation shell for vaporization, ensuring efficient heat dissipation under normal operating conditions.

[0017] This invention, by setting up an annular baffle, a sealed cavity, a piston, and a slide rod, utilizes local temperature changes to cause the inert gas in the sealed cavity to contract when the water-swellable layer expands upon contact with water. This causes the piston to move and apply mechanical pressure to the sidewall of the water-swellable layer, further squeezing out the water absorbed inside the water-swellable layer. This effectively improves drainage efficiency and prevents water from lingering inside the water-swellable layer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ; Figure 2 This is a cross-sectional view of the overall structure of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram showing the connection between the heat dissipation shell and the annular baffle in this invention; Figure 5 This is a cross-sectional view of the heat dissipation shell of the present invention; Figure 6 This is a schematic diagram showing the connection between the water-blocking shell and the heat-conducting plate of the present invention; Figure 7 This is the water-swellable layer in this invention.

[0019] In the diagram: 1. Wire core; 2. Insulation layer; 3. Inner sheath; 4. Outer sheath; 5. Water-swellable layer; 6. Heat dissipation shell; 6. Water inlet groove; 601. Exhaust micropore; 602. Second flow groove; 603. Water-blocking shell; 7. Empty groove; 8. Heat-conducting plate; 9. First flow groove; 10. Water inlet groove; 11. Annular baffle; 12. Sealing cavity; 13. Piston; 14. Sliding rod; 15. Air groove; 16. Heat dissipation fins; 17. Capillary tube; 18. Detailed Implementation

[0020] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0021] like Figures 1 to 7 The low-loss medium-voltage water-blocking power cable shown includes several conductive cores 1. The surface of each core 1 is covered with an insulation layer 2. The insulation layer 2 is covered with an inner sheath 3. A water-blocking composite layer is disposed on the surface of the inner sheath 3. An outer sheath 4 is disposed outside the water-blocking composite layer. The water-blocking composite layer includes: Several heat dissipation shells 6 are linearly arrayed and fixedly connected to the outside of the inner sheath 3. A water-blocking shell 7 is provided between two adjacent heat dissipation shells 6. The outer wall of each water-blocking shell 7 is covered with a water-swellable layer 5. Each water-swellable layer 5 is covered with an outer sheath 4. The heat dissipation shell 6 has several water inlet grooves 601 arranged in a ring array on both sides, and exhaust micropores 602 arranged in a ring array on the outer wall of the heat dissipation shell 6. After the water-expanding layer 5 absorbs water and expands, it is squeezed against the water-blocking shell 7 and the outer sheath 4. Under the reverse squeezing of the water-blocking shell 7 and the outer sheath 4, the water in the water-expanding layer 5 enters the heat dissipation shell 6 through the water inlet grooves 601, is heated by the heat dissipation shell 6, and evaporates through the exhaust micropores 602. In the prior art, this technical solution can solve the above problems. After the water-swellable layer 5 absorbs water and expands, it can temporarily block the water inlet channel. However, the water that has seeped into the cable cannot be discharged on its own. If it remains on the surface of the insulation layer 2 or in the structural gaps for a long time, it will continuously induce water tree growth, resulting in increased insulation loss and decreased long-term operational reliability of the cable. The specific operation is as follows: Under normal cable operation, the conductive core 1 is energized and heats up. The heat is transferred to the heat dissipation shell 6 through the insulation layer 2 and the inner sheath 3. The heat dissipation shell 6 is made of thermally conductive material. The exhaust micro-holes 602 on its outer wall can maintain the air pressure balance between the inside and outside and dissipate some heat to the outside, playing an auxiliary role in heat dissipation. At this time, the water-swellable layer 5 covering the outer wall of the water-blocking shell 7 located between adjacent heat dissipation shells 6 is in a dry and shrinking state. The outer sheath 4 and the water-swellable layer 5 maintain a gap, and there is no water accumulation inside the cable. When the cable is laid in a humid environment or when moisture seeps into the outer sheath 4 due to accidental damage, the moisture first comes into contact with the water-swellable layer 5. The water-swellable layer 5, like water-absorbing and swelling rubber, quickly absorbs the moisture and expands in volume. On the one hand, it squeezes the water-blocking shell 7 inward and the outer sheath 4 outward, forming a tight radial seal to prevent the moisture from continuing to diffuse axially or radially. On the other hand, the squeezing force generated by the expansion will drive the moisture that has been absorbed into the water-swellable layer 5 to be discharged along the pressure direction. Since the heat dissipation shell 6 has water inlet grooves 601 in the annular array on both sides, under the mutual squeezing action between the water-swellable layer 5, the water-blocking shell 7, and the outer sheath 4, the moisture is forced to enter the interior of the heat dissipation shell 6 through the water inlet grooves 601. Since the heat dissipation shell 6 is in close contact with the inner sheath 3, its temperature is higher than that of the cable's external environment. The moisture entering the heat dissipation shell 6 vaporizes into water vapor under the action of high temperature. The water vapor continuously evaporates into the external atmosphere of the cable through the exhaust micropores 602 opened in the annular array on the outer wall of the heat dissipation shell 6. This process realizes the active discharge and evaporation of the infiltrated moisture, avoiding the long-term retention of moisture on the surface of the insulation layer 2. At the same time, as the moisture is discharged, the water-expanding layer 5 will shrink slightly, maintaining a sealed contact without generating excessive stress, and can repeatedly cope with subsequent water seepage.

[0022] As a further embodiment of the present invention, the outer wall of the water-blocking shell 7 is provided with a number of slots 8 in an annular array, and a heat-conducting plate 9 is slidably connected in the slots 8. The heat-conducting plate 9 is connected to the water-expanding layer 5. The water-blocking shell 7 is symmetrically provided with a first flow groove 10 at the position corresponding to the empty groove 8, and the heat dissipation shell 6 is provided with a second flow groove 603 at the position corresponding to the first flow groove 10, so that airflow can flow. The water-blocking shell 7 has a water inlet trough 11 at the position corresponding to the empty trough 8, and the drinking water trough and the inlet trough 601 are positioned accordingly. When the water-expanding layer 5 is dry, the two ends of the heat-conducting plate 9 seal the water inlet trough 11. After the water-expanding layer 5 absorbs water and expands, it pushes the heat-conducting plate 9 to move downward, and the two ends of the heat-conducting plate 9 seal the first connecting groove, thus opening the water inlet trough 11.

[0023] Specifically, when the water-expanding layer 5 is in a dry and shrinking state, the heat-conducting plate 9 connected to it is located at the initial high position in the empty groove 8. At this time, the two ends of the heat-conducting plate 9 seal the inlet of the water inlet 11 to prevent external dust or moisture from directly entering the cable through the water inlet 601 and the water inlet 11. At the same time, the first flow groove 10 symmetrically opened on the water-blocking shell 7 and the corresponding second flow groove 603 opened on the heat dissipation shell 6 are in a conductive state. When the cable is working normally, the heat generated by the conductive core 1 causes the temperature of the heat dissipation shell 6 to rise. The internal air expands due to heat. The airflow can form a micro-circulation between the water-blocking shell 7 and the heat dissipation shell 6 through the first flow groove 10 and the second flow groove 603, so as to dissipate the heat to the outside of the outer sheath 4 in time and effectively reduce the internal temperature of the cable. When water passes through the outer sheath 4 and comes into contact with the water-swellable layer 5, the water-swellable layer 5 quickly absorbs water and expands. As its volume increases, it pushes the heat-conducting plate 9 downward along the slot 8. After the heat-conducting plate 9 moves downward, its two ends block the originally open first flow channel 10, cutting off the airflow circulation channel. On the one hand, this prevents water vapor or liquid water from entering the inner sheath 3 through the flow channel. On the other hand, it makes the heat-conducting plate 9 contact the surface of the inner sheath 3. The heat-conducting plate 9 itself is a metal plate of heat-conducting material, and a heat-conducting adhesive layer can be provided between the water-swellable layer 5 and the heat-conducting plate 9. This can transfer the heat on the inner sheath 3 to the water-swellable layer 5. Since there is water in the water-swellable layer 5, the heat-conducting plate 9 is cooled through the water-swellable layer 5, which is beneficial for cooling the local area. Then, the heat is diffused to the surrounding area through the heat conduction effect of the inner sheath 3 itself, thus achieving auxiliary heat dissipation. After the two ends of the heat-conducting plate 9 leave the sealed position of the water inlet 11, the water inlet 11 is opened. Since the position of the water inlet 11 corresponds to the water inlet 601 on the heat sink 6, the water generated by the water expansion layer 5 and the seeping liquid water enter the interior of the heat sink 6 through the water inlet 11 and the water inlet 601 in sequence. The heat sink 6 is heated by the inner sheath 3, and the temperature is high. The water entering the shell quickly vaporizes. The water vapor evaporates to the outside atmosphere through the exhaust micro-holes 602 on the outer wall of the heat sink 6, realizing active drainage. When the water is completely drained and the water-expanding layer 5 shrinks, the heat conduction plate 9 resets under the action of elastic restoring force or its own weight, reseals the water inlet trough 11 and opens the first flow channel 10, and the cable returns to the heat dissipation mode of being dry.

[0024] As a further embodiment of the present invention, the heat dissipation shell 6 is symmetrically provided with annular baffles 12 at both ends, and the annular baffles 12 abut against the end of the water-swellable layer 5 so that the end of the water-swellable layer 5 does not contact the water inlet trough 11. The heat sink 6 has symmetrically arranged sealing cavities 13 at both ends. A piston 14 is slidably connected in the sealing cavity 13. Several sliding rods 15 are fixedly connected to the side wall of the piston 14. Several sliding rods 15 are fixedly connected to the annular baffle 12 at the corresponding position. The side wall of the heat sink 6 has an air groove 16 that communicates with the sealing cavity 13. The side of the sealing cavity 13 near the annular baffle 12 is filled with inert gas. Specifically, during the process of the water-swellable layer 5 expanding upon contact with water, the temperature and air pressure of the sealed cavity 13 decrease, and the piston 14 drives the slide rod 15 to move the annular baffle 12, squeezing the side wall of the water-swellable layer 5 to squeeze out excess water, which then enters the heat dissipation shell 6 through the water inlet trough 11 and the water inlet trough 601 for vaporization.

[0025] As a further embodiment of the present invention, a number of heat dissipation fins 17 are arranged in a ring array inside the heat dissipation shell 6; capillary channels 18 are symmetrically arranged on the side walls of the heat dissipation fins 17; water inside the heat dissipation shell 6 is diverted to the side walls of the heat dissipation fins 17 through the capillary channels 18, thereby increasing the heating area and increasing the vaporization rate.

[0026] As a further embodiment of the present invention, the outer wall of the heat dissipation shell 6 is coated with a hydrophobic layer; a moisture-permeable membrane is provided inside the heat dissipation shell 6, which allows water vapor to pass through and prevents liquid water from passing through; this helps to prevent water from remaining on the heat dissipation shell 6 and clogging the exhaust micropores 602.

[0027] The working principle of this invention is as follows: Under normal operating conditions of the cable, the conductive core 1 is energized and heats up. The heat is transferred to the heat dissipation shell 6 through the insulation layer 2 and the inner sheath 3. The heat dissipation shell 6 is made of thermally conductive material. The exhaust micro-holes 602 on its outer wall can maintain the air pressure balance between the inside and the outside and dissipate some of the heat to the outside, thus playing an auxiliary role in heat dissipation. At this time, the water-swellable layer 5 covering the outer wall of the water-blocking shell 7 located between adjacent heat dissipation shells 6 is in a dry and shrinking state. The outer sheath 4 and the water-swellable layer 5 maintain a gap, and there is no water accumulation inside the cable. When the cable is laid in a humid environment or when moisture seeps into the outer sheath 4 due to accidental damage, the moisture first comes into contact with the water-swellable layer 5. The water-swellable layer 5, like water-absorbing and swelling rubber, quickly absorbs the moisture and expands in volume. On the one hand, it squeezes the water-blocking shell 7 inward and the outer sheath 4 outward, forming a tight radial seal to prevent the moisture from continuing to diffuse axially or radially. On the other hand, the squeezing force generated by the expansion will drive the moisture that has been absorbed into the water-swellable layer 5 to be discharged along the pressure direction. Since the heat dissipation shell 6 has water inlet grooves 601 in the annular array on both sides, under the mutual squeezing action between the water-swellable layer 5, the water-blocking shell 7, and the outer sheath 4, the moisture is forced to enter the interior of the heat dissipation shell 6 through the water inlet grooves 601. Since the heat dissipation shell 6 is in close contact with the inner sheath 3, its temperature is higher than that of the cable's external environment. The moisture entering the heat dissipation shell 6 vaporizes into water vapor under the action of high temperature. The water vapor continuously evaporates into the external atmosphere of the cable through the exhaust micropores 602 opened in the annular array on the outer wall of the heat dissipation shell 6. This process realizes the active discharge and evaporation of the infiltrated moisture, avoiding the long-term retention of moisture on the surface of the insulation layer 2. At the same time, as the moisture is discharged, the water-expanding layer 5 will shrink slightly, maintaining a sealed contact without generating excessive stress, and can repeatedly cope with subsequent water seepage.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A low-loss medium-voltage water-blocking power cable, comprising several conductive cores (1), wherein the surface of each core (1) is covered with an insulation layer (2), the surface of the insulation layer (2) is covered with an inner sheath (3), the surface of the inner sheath (3) is provided with a water-blocking composite layer, and an outer sheath (4) is provided outside the water-blocking composite layer, characterized in that, The water-blocking composite layer includes: Several heat dissipation shells (6) are linearly arrayed and fixedly connected to the outside of the inner sheath (3). A water-blocking shell (7) is provided between two adjacent heat dissipation shells (6). The outer wall of each water-blocking shell (7) is covered with a water-swellable layer (5), and each water-swellable layer (5) is covered with an outer sheath (4). The heat dissipation shell (6) has several water inlet grooves (601) arranged in a ring array on both sides, and the outer wall of the heat dissipation shell (6) has exhaust micropores (602) arranged in a ring array. After the water-swellable layer (5) absorbs water and expands, it is squeezed against the water-blocking shell (7) and the outer sheath (4). Under the reverse squeezing of the water-blocking shell (7) and the outer sheath (4), the water in the water-swellable layer (5) enters the heat dissipation shell (6) through the water inlet grooves (601), is heated by the heat dissipation shell (6), and evaporates through the exhaust micropores (602).

2. The low-loss medium-voltage water-blocking power cable according to claim 1, characterized in that, The outer wall of the water-blocking shell (7) is provided with several slots (8) arranged in an annular array. A heat-conducting plate (9) is slidably connected in the slots (8). The heat-conducting plate (9) is connected to the water-expanding layer (5). The water-blocking shell (7) is symmetrically provided with a first flow groove (10) at the position corresponding to the empty groove (8), and the heat dissipation shell (6) is provided with a second flow groove (603) at the position corresponding to the first flow groove (10) so that airflow can flow; The water-blocking shell (7) has a water inlet trough (11) at the position corresponding to the empty trough (8), and the drinking water trough is positioned opposite to the water inlet trough (601).

3. A low-loss medium-voltage water-blocking power cable according to claim 2, characterized in that, The heat dissipation shell (6) is symmetrically provided with annular baffles (12) at both ends. The annular baffles (12) abut against the end of the water-swellable layer (5) so that the end of the water-swellable layer (5) does not come into contact with the water inlet tank (11).

4. A low-loss medium-voltage water-blocking power cable according to claim 3, characterized in that, The heat dissipation shell (6) has symmetrically arranged sealing cavities (13) at both ends. A piston (14) is slidably connected in the sealing cavity (13). Several sliding rods (15) are fixedly connected to the side wall of the piston (14). Several sliding rods (15) are fixedly connected to the corresponding annular baffles (12). An air groove (16) is opened on the side wall of the heat dissipation shell (6) and communicates with the sealing cavity (13). The side of the sealing cavity (13) near the annular baffle (12) is filled with inert gas.

5. A low-loss medium-voltage water-blocking power cable according to claim 1, characterized in that, The heat sink (6) has several heat sink fins (17) arranged in a ring array inside.

6. A low-loss medium-voltage water-blocking power cable according to claim 5, characterized in that, The heat dissipation fins (17) are symmetrically provided with capillary channels (18) on their sidewalls.

7. A low-loss medium-voltage water-blocking power cable according to claim 1, characterized in that, The outer wall of the heat dissipation shell (6) is coated with a hydrophobic layer.

8. A low-loss medium-voltage water-blocking power cable according to claim 2, characterized in that, The heat-conducting plate (9) is a metal plate.

9. A low-loss medium-voltage water-blocking power cable according to claim 1, characterized in that, The heat dissipation shell (6) is provided with a moisture-permeable membrane, which allows water vapor to pass through but prevents liquid water from passing through.

10. A low-loss medium-voltage water-blocking power cable according to claim 1, characterized in that, The water-swellable layer (5) is an expanded rubber.

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