High current carrying capacity low wind pressure overhead insulated cable and its preparation method

Abstract

The application provides a high-current low-wind-pressure overhead insulated cable, which comprises a conductor, a conductor shielding layer and an outer insulation layer arranged in sequence from inside to outside; the outer insulation layer comprises an annular body and a plurality of convex portions uniformly and spacedly distributed along the outer periphery of the annular body, and a concave portion is formed between two adjacent convex portions; the convex portion is T-shaped, comprising an outer arc segment, the end of the outer arc segment is connected with the annular body through an upper arc segment and a lower arc segment, and the upper arc segment and the lower arc segment are connected in an S shape. The application also provides a preparation method of the aforementioned overhead insulated cable. The application has the advantages that the insulation isolation of the central conductor and the outer layer conductor is arranged, and the T-shaped convex portion structure design of the surface of the outer insulation layer reduces the conductor AC resistance and the wind resistance coefficient, improves the heat dissipation efficiency, and realizes the beneficial effects of the current-carrying capacity improvement, the wind load reduction, the probability reduction of external force damage and the like.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a high current-carrying, low wind pressure overhead insulated cable and its preparation method. Background Technology

[0002] Overhead insulated cables are a type of overhead cable with an insulating sheath covering the conductor. Because the insulation layer provides electrical insulation and physical protection for the conductor, overhead insulated cables are advantageous for shortening the phase-to-phase distance, saving line corridor space, reducing the incidence of phase-to-phase short circuits and grounding faults, and improving line safety and reliability. They also possess advantages such as high mechanical strength, strong corrosion resistance, and strong weather resistance. Therefore, overhead insulated cables are widely used in urban and rural power distribution network projects, and are particularly suitable for areas with abundant trees, severe pollution, harsh environments, and dense populations.

[0003] However, the insulation layer also increases the external thermal resistance of the conductor and reduces its heat dissipation, resulting in a lower allowable current-carrying capacity for overhead insulated cables compared to bare overhead conductors of the same cross-sectional area. This can lead to insufficient current-carrying capacity during peak load periods, creating a bottleneck in power transmission. Furthermore, due to the good weather resistance of overhead insulated cables, their operating environments are often located in windy areas such as coastal regions, valleys, and islands. Strong winds generate significant wind pressure on overhead cable lines; in terms of wind load, 50% to 70% of the wind load on the entire transmission line is borne by the overhead cable. In addition to the overhead cable itself needing to withstand wind loads, its supporting towers must also bear the combined effect of the wind load transmitted from the cable and the wind load on the tower itself. Therefore, reducing the wind load on overhead cables is crucial for reducing line construction costs and improving line operational safety.

[0004] In existing technologies, methods to increase the current-carrying capacity of overhead insulated cables mainly include increasing the conductor cross-section, inserting circulating cooling pipes into the cable, and using insulation materials with better high-temperature resistance and thermal conductivity. The main drawbacks of these methods are: 1. They increase the cost of the overhead cable line itself; 2. They lead to increased weight, structural changes, and higher operating temperatures in the overhead cable, significantly altering its operating conditions and reducing the reliability of the line; 3. In practical applications, simultaneous optimization and modification of supporting towers, connecting devices, and supporting electrical systems are required, substantially increasing the line construction cost.

[0005] In existing technologies, the main method for reducing wind load on overhead insulated cables is to add a certain number of protrusions or grooves along the circumferential direction of the outer insulation layer. This increases the surface roughness of the overhead insulated cable, which delays the fluid boundary layer separation point on the cable surface in a high-speed flow field, making the negative pressure zone on its back side smaller than that of ordinary overhead insulated cables, thereby reducing the resistance formed by the pressure difference between the windward and leeward sides of the cable. Although this method can reduce the wind resistance coefficient of the cable, it still has the following drawbacks: 1. The wind resistance of overhead insulated cables is closely related to the shape, size, and number of grooves. However, the groove structures provided in existing methods are limited to a single form, making it difficult to adjust and optimize according to the cable's outer diameter and wind speed, resulting in an insignificant wind pressure reduction effect; 2. The ridged, rectangular, and V-shaped groove designs provided in existing methods all have sharp points, which can easily cause electric field concentration and affect insulation reliability; 3. The protruding parts on the surface are easily squeezed or worn during transportation and construction, causing damage to the insulation layer and creating safety hazards. Summary of the Invention

[0006] To address the aforementioned shortcomings, the present invention aims to provide a high current-carrying, low wind pressure overhead insulated cable to solve the problems of low current-carrying capacity and poor wind resistance in existing cables.

[0007] This invention provides a high current-carrying, low wind pressure overhead insulated cable. The overhead insulated cable includes a conductor, a conductor shielding layer, and an outer insulation layer arranged sequentially from the inside out. The outer insulation layer includes an annular body and a plurality of protrusions evenly spaced along the outer circumference of the annular body, with a recess formed between two adjacent protrusions. The protrusions are T-shaped and include an outer arc segment. The end of the outer arc segment is connected to the annular body through an upper arc segment and a lower arc segment, and the upper and lower arc segments are connected in an S-shape.

[0008] Preferably, the material of the outer insulation layer is cross-linked polyethylene or polypropylene.

[0009] Preferably, the thickness of the outer insulating layer is 3 to 5 mm.

[0010] Preferably, the center of the outer arc segment coincides with the center of the outer diameter circle of the overhead insulated cable, and the radius R of the outer arc segment is half of the outer diameter of the overhead insulated cable; both the upper and lower arc segments are semicircular, and both have a radius r.

[0011] Preferably, when the outer diameter of the overhead insulated cable is 20-30mm, the central angle θ corresponding to the outer arc segment is 7.5 degrees, and the radius r is 0.2-0.4mm; when the outer diameter of the overhead insulated cable is 30-40mm, the central angle θ corresponding to the outer arc segment is 6 degrees, and the radius r is 0.3-0.5mm; when the outer diameter of the overhead insulated cable is greater than 40mm, the central angle θ corresponding to the outer arc segment is 5 degrees, and the radius r is 0.3-0.5mm.

[0012] Preferably, the conductor has a multi-layer stranded structure, with an inner insulating layer between every two single-wire layers.

[0013] Preferably, the inner insulation layer is an insulating non-woven fabric with a thickness of 0.3 mm to 0.5 mm.

[0014] Preferably, the twisting directions of adjacent single-wire layers are opposite.

[0015] The present invention also provides a method for preparing the aforementioned overhead insulated cable, comprising the following steps:

[0016] S1. Making the center conductor: Take multiple conductor wires and twist them together in a 1+6 structure to obtain the center conductor;

[0017] S2. Fabricate the first inner insulation layer: Wrap a layer of non-woven insulating tape around the outer periphery of the central conductor;

[0018] S3. Fabrication of the outer conductor: Multiple conductor single wires are evenly distributed and tightly twisted around the outer periphery of the first inner insulation layer to form the outer conductor; when the number of twisted layers of the outer conductor is greater than 2, an inner insulation layer is set outside the second single wire layer.

[0019] S4. Use a cable extruder to extrude the conductor shielding layer and the outer insulation layer on the outer surface of the outer conductor, and cool the overhead insulated cable after extrusion molding.

[0020] The advantages of this invention are that by setting the insulation isolation between the center conductor and the outer conductor, and designing the T-shaped protrusion structure on the surface of the outer insulation layer, the AC resistance and wind resistance coefficient of the conductor are reduced, the heat dissipation efficiency is improved, and the beneficial effects such as increasing the current carrying capacity, reducing wind load, and reducing the probability of external force damage are achieved. Moreover, the cable manufacturing and construction process of this invention is simple, and there is no need to change the overall structure, operating conditions and manufacturing process of the overhead insulated cable. Only the insulation layer extrusion mold needs to be modified, resulting in a small increase in cost and easy industrial promotion and use. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overhead insulated cable in Example 1;

[0022] Figure 2This is a schematic diagram of the structure of the outer insulation layer in Example 1;

[0023] Figure 3 Schematic diagram of the outer insulation layer extrusion die;

[0024] Figure 4 This is a schematic diagram of the overhead insulated cable in Example 2;

[0025] Figure 5 This is a schematic diagram of the structure in Comparative Example 1;

[0026] Figure 6 This is a schematic diagram of the structure in Comparative Example 2;

[0027] Figure 7 This is a schematic diagram of the structure in Comparative Example 3.

[0028] Component designation explanation:

[0029] 11. Central conductor

[0030] 12 First Inner Insulation Layer

[0031] 13 First Conductor

[0032] 14 Second Inner Insulation Layer

[0033] 15 Second Conductor

[0034] 2 Conductor shielding layer

[0035] 3. Outer insulation layer

[0036] 31 convex part

[0037] 32 recess

[0038] 33. Ring-shaped body

[0039] 4. Extrusion die

[0040] 41 Groove

[0041] 301 outer insulation layer

[0042] 302 outer insulation layer

[0043] 303 outer insulation layer Detailed Implementation

[0044] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0045] In the description of this invention, it should be noted that the terms "center," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] like Figure 1 and Figure 2 As shown, the present invention provides a high current-carrying, low wind pressure overhead insulated cable, which includes a conductor, a conductor shielding layer 2, and an outer insulation layer 3 arranged sequentially from the inside to the outside.

[0047] To improve upon the defects existing in current overhead insulated cables, the outer insulation layer 3 of this invention includes an annular body 33 and a plurality of protrusions 31 evenly spaced along the outer periphery of the annular body 33. Each protrusion 31 is T-shaped and includes an outer arc segment AB. One end of the outer arc segment AB is tangent to the upper arc segment AC and connected to the annular body 33 through the upper arc segment AC and the lower arc segment CE; the other end is tangent to the upper arc segment BD and connected to the annular body 33 through the upper arc segment BD and the lower arc segment DF. The upper arc segment AC and the lower arc segment CE, as well as the upper arc segment BD and the lower arc segment DF, are all connected in an S-shape.

[0048] Specifically, the center of the outer arc segment AB coincides with the center of the outer diameter circle of the overhead insulated cable, and the radius R of the outer arc segment AB is half the outer diameter of the overhead insulated cable; the upper arc segments AC / BD and the lower arc segments CE / DF are both semicircles with a radius r. Therefore, the number of protrusions 31 in the outer insulation layer 3 of this invention is determined by their corresponding central angle θ, the height of the protrusion 31 is determined by the radius r, and the shape of the protrusion 31 is determined by θ, r, and R. Simultaneously, an inverted T-shaped recess 32 is formed between two adjacent protrusions 31, and the central angle corresponding to the recess 32 is the same as that of the protrusion 31.

[0049] Furthermore, when the outer diameter of the overhead insulated cable is 20–30 mm, the central angle θ corresponding to the outer arc segment AB is 7.5 degrees, and the radius r is 0.2–0.4 mm; when the outer diameter of the overhead insulated cable is 30–40 mm, the central angle θ corresponding to the outer arc segment AB is 6 degrees, and the radius r is 0.3–0.5 mm; when the outer diameter of the overhead insulated cable is greater than 40 mm, the central angle θ corresponding to the outer arc segment AB is 5 degrees, and the radius r is 0.3–0.5 mm.

[0050] Preferably, the outer insulation layer 3 used in this invention is made of cross-linked polyethylene or polypropylene, with a thickness of 3 to 5 mm. Here, "thickness" refers to the distance from the inner diameter circle of the annular body 33 to the outer arc segment AB.

[0051] The present invention provides uniformly distributed protrusions 31 on the surface of the insulating layer 3, which has the following three beneficial effects:

[0052] 1. While maintaining the same cable outer diameter, it can effectively increase the cable surface heat dissipation area, improving heat dissipation. Simultaneously, the airflow generates vortex airflow within the recess 32, which enhances convection, helping to remove heat from the cable surface and reduce conductor temperature, thereby significantly increasing the cable's current carrying capacity. Compared to ordinary overhead insulated cables of the same outer diameter, its current carrying capacity can be increased by 10%-20%.

[0053] 2. Because the pressure of the vortex airflow is lower than the external airflow pressure, the fluid boundary layer near the cable surface is attracted by the vortex airflow and adheres tightly to the cable surface. This significantly delays the separation point of the fluid boundary layer on the cable surface in a high-speed flow field, resulting in a smaller negative pressure zone on its back side compared to ordinary overhead insulated cables. This reduces the resistance formed by the pressure difference between the windward and leeward sides of the cable. Those skilled in the art can adjust the number, depth, and shape of the protrusions 31 and concave portions 32 to adapt to the wind pressure design requirements of overhead insulated cables with different outer diameters, satisfying different incoming wind velocities and achieving optimal results.

[0054] 3. The center of the outer arc segment AB coincides with the center of the outer diameter circle of the overhead insulated cable, and is connected to the annular body 33 through the upper arc segment AC / BD and the lower arc segment CE / DF. This ensures that the outer insulation layer 3 has no sharp points or protrusions, making it less susceptible to wear during transportation and construction. Simultaneously, the protrusion 31 also provides protection for the annular body 33, reducing the probability of damage to the insulation layer 3 from external forces.

[0055] like Figure 1 As shown, the conductor of this invention has a multi-layer stranded structure, with each single-wire layer concentrically stranded and adjacent single-wire layers stranded in opposite directions. An inner insulation layer is provided between every two single-wire layers, from the inside out. Specifically, the inner insulation layer is an insulating non-woven fabric with a thickness of 0.3mm to 0.5mm. The first inner insulation layer 12 divides the conductor into a center conductor 11 and an outer conductor. The center conductor 11 is made of seven round aluminum single wires tightly stranded in a 1+6 configuration, forming a tightly compressed circular structure. The outer conductor is also a tightly compressed circular structure made of multiple round aluminum single wires stranded in multiple layers. Specifically, the aforementioned round aluminum single wires are ordinary hard aluminum wire, heat-resistant aluminum alloy wire, or high-strength aluminum alloy wire.

[0056] When a cable is in operation, under the influence of an alternating electric field, the induced electric field causes the current to tend to flow along the conductor surface, reducing the effective current-carrying cross-section and increasing the resistance. The larger the cross-section, the more pronounced the skin effect. This invention uses an inner insulation layer to divide the conductor into mutually insulated inner and outer blocks, allowing current to flow only within each block, reducing the skin effect, and thus effectively increasing the cable's current-carrying capacity.

[0057] The following are embodiments and comparative examples of the present invention:

[0058] Example 1

[0059] like Figure 1 and Figure 2 The overhead insulated cable of Embodiment 1 includes, from the inside out, a center conductor 11, a first inner insulation layer 12, a first conductor 13 (i.e., an outer conductor), a conductor shielding layer 2, and an insulation layer 3. The center conductor 1 is made of 7 round aluminum single wires twisted together in a 1+6 structure to form a tightly compressed circular structure with a compression coefficient of 0.89 and a diameter of 3 mm for the round aluminum single wires.

[0060] The thickness of the first inner insulation layer 12 is 0.3 mm, and the material is non-woven fabric insulation tape, which is wrapped around the outside of the center conductor 11 using a seamless wrapping process.

[0061] The first conductor 13 is made of 30 round aluminum single wires twisted together in a 12+18 configuration outside the first inner insulation layer 12 to form a tightly compressed circular structure with a compression coefficient of 0.89.

[0062] The single-wire layers contained in the center conductor 11 and the first conductor 13 are concentrically stranded, with adjacent single-wire layers stranded in opposite directions. The diameter of the round aluminum single wire is 3mm.

[0063] The conductor shielding layer 2 is made of cross-linked semi-conductive shielding material with a thickness of 0.5 mm. The outer insulation layer 3 is made of cross-linked polyethylene with a thickness of 3.4 mm. In Example 1, the conductor shielding layer 2 and the outer insulation layer 3 are extruded onto the outer surface of the first conductor 13 using a double-layer co-extrusion method. The outer insulation layer 3 is extruded through the first extrusion channel of the cable extruder, and the conductor shielding layer 2 is extruded through the second extrusion channel. Before extrusion, the components are assembled in the first channel as follows: Figure 3 The extrusion die 4 shown has multiple grooves 41 evenly spaced along the circumference, with each groove 41 corresponding to a protrusion 31. The outer diameter of the extruded cable is 27 mm. The surface of the outer insulation layer 3 has 24 protrusions 31 evenly spaced. The central angle θ corresponding to the outer arc segment AB is 7.5 degrees, and the corresponding radius R is 13.5 mm. The radius r of the upper arc segment AC / BD and the lower arc segment CE / DF is 0.3 mm, and the depth of the recess 32 is 1.2 mm.

[0064] The method for preparing the overhead insulated cable in Example 1 includes the following steps:

[0065] S1. Making the center conductor 11: Take 7 conductor wires and twist them together in a 1+6 structure to obtain the center conductor 11;

[0066] S2. Fabrication of the first inner insulation layer 12: A layer of non-woven insulating tape is wrapped around the outer periphery of the center conductor 11 using a seamless wrapping process.

[0067] S3. Making the outer conductor: Take 30 conductor wires, and use a stranding machine to evenly distribute the 30 conductor wires in a 12+18 structure and tightly twist them around the outer periphery of the first inner insulation layer 12 to form the first conductor 13.

[0068] S4. Assemble the extrusion die 4 in the first channel of the cable extruder. Take the product from step 3 and feed it into the cable extruder. Add insulating particles and shielding particles to the feed cylinder of the cable extruder. Extrude the conductor shielding layer 2 and the outer insulation layer 3 on the outer surface of the first conductor 13 in a double-layer co-extrusion manner. The first extrusion channel of the cable extruder extrudes the outer insulation layer 3, and the second extrusion channel extrudes the conductor shielding layer 2. After extrusion molding, cool the cable.

[0069] Example 2

[0070] like Figure 4 As shown, the overhead insulated cable of Embodiment 2 includes, from the inside out, a center conductor 11, a first inner insulation layer 12, a first conductor 13, a second inner insulation layer 14, a second conductor 15, a conductor shielding layer 2, and an outer insulation layer 3. One difference from Embodiment 1 is that, in addition to the first conductor 13, the outer conductor also includes a second conductor 15, with a second insulation layer 14 positioned between the first conductor 13 and the second conductor 15. The second insulation layer 14 is wrapped around the outer circumference of the first conductor 13 using a seamless wrapping process, and has a thickness of 0.3 mm, made of non-woven fabric insulation tape. The second conductor 15 is formed by twisting 24 round aluminum single wires outside the second inner insulation layer 4 to create a tightly compressed circular structure with a compression coefficient of 0.89. The single wire layers contained in the center conductor 11, the first conductor 13, and the second conductor 15 are concentrically twisted, with adjacent single wire layers twisted in opposite directions. The diameter of each round aluminum single wire is 3 mm.

[0071] The second difference between Example 2 and Example 1 is that the thickness of the outer insulation layer 3 is 4.0 mm. The outer diameter of the extruded cable is 32 mm. The surface of the outer insulation layer 3 has 30 protrusions 31 evenly spaced. The central angle θ corresponding to the outer arc segment AB is 6 degrees, and the corresponding radius R is 16 mm. The radius r of the upper arc segment AC / BD and the lower arc segment CE / DF is 0.4 mm, and the depth of the recess 32 is 1.6 mm.

[0072] The method for preparing the overhead insulated cable in Example 2 includes the following steps:

[0073] S1. Making the center conductor 11: Take 7 conductor wires and twist them together in a 1+6 structure to obtain the center conductor 11;

[0074] S2. Fabrication of the first inner insulation layer 12: A layer of non-woven insulating tape is wrapped around the outer periphery of the center conductor 11 using a seamless wrapping process.

[0075] S3. Fabrication of the outer conductor: Take 30 conductor wires and evenly distribute them in a 12+18 configuration using a stranding machine, then tightly strand them around the outer periphery of the first inner insulation layer 12 to form the first conductor 13. Next, wrap a layer of non-woven insulating tape around the outer periphery of the first conductor 13 using a seamless wrapping process to form the second insulation layer 14. Then, evenly distribute and tightly strand 24 conductor wires around the outer periphery of the second inner insulation layer 14 using a stranding machine to form the second conductor 15.

[0076] S4. Assemble the extrusion die 4 in the first channel of the cable extruder. Take the product from step 3 and feed it into the cable extruder. Add insulating particles and shielding particles to the feed cylinder of the cable extruder. Extrude the conductor shielding layer 2 and the outer insulation layer 3 on the outer surface of the second conductor 15 in a double-layer co-extrusion manner. The first extrusion channel of the cable extruder extrudes the outer insulation layer 3, and the second extrusion channel extrudes the conductor shielding layer 2. After extrusion molding, cool the cable.

[0077] Comparative Example 1

[0078] like Figure 5 As shown, the difference between Comparative Example 1 and Example 1 is that the radius r of the upper and lower arc segments of the outer insulating layer 301 is 0.1 mm, and the depth of the recess is 0.4 mm. All other structures, parameters, and preparation methods are the same as in Example 1.

[0079] Comparative Example 2

[0080] like Figure 6 As shown, the difference between Comparative Example 2 and Example 1 is that the central angle θ corresponding to the protrusions of the outer insulating layer 302 is 90 degrees, and the number of protrusions is 4. Other structures, parameters, and preparation methods are the same as in Example 1.

[0081] Comparative Example 3

[0082] like Figure 7 As shown, the difference between Comparative Example 3 and Example 1 is that Comparative Example 3 does not have an inner insulating layer in its conductor, and the outer insulating layer 303 is extruded using a die with a circular cross-section. The extruded outer insulating layer 303 has a smooth surface without protrusions or depressions. Other structures, parameters, and preparation methods are the same as in Example 1.

[0083] The following performance tests were performed on the cables of Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3:

[0084] (1) Current carrying capacity test: Apply an estimated test current according to the cable's allowable long-term operating temperature. After reaching a steady state, gradually adjust the test current so that the conductor temperature approaches the cable's allowable long-term operating temperature. When the temperature change is ±2℃ within 2 hours, record the temperature and current parameters. In the test, the cable's long-term operating temperature is taken as 90℃ and the ambient temperature as 25℃.

[0085] (2) Wind Tunnel Test: After the cable samples were arranged in the wind tunnel test area, the wind force on the cable was measured in real time at different wind speeds within a wind speed range of 10–50 m / s, using a six-dimensional force sensor connected to the cable. The collected force data is represented as the three-dimensional force F on the cable at the measured wind speed. x F y F z Among them, F x For the cable to be subjected to force along the windward side, F y For the cable to be subjected to force in the axial direction, F z The cable is subjected to force in a direction perpendicular to the bottom surface of the test area. Then, the overall wind resistance coefficient C of the cable is calculated using equation (1). d .

[0086]

[0087] Where: ρ is the ambient air density (kg / m³) 3 ); u is the wind speed (m / s); L is the cable length (m); d is the cable outer diameter (mm).

[0088] The tests were conducted on Example 1 and Comparative Examples 1-3 according to the above test methods, and the test results are shown in Table 1:

[0089] Table 1

[0090]

[0091] As shown in Table 1, under the same conditions, the current carrying capacity of Example 1 is significantly higher than that of Comparative Examples 1 to 3, and 20% higher than that of the ordinary overhead insulated cable of the same specification in Comparative Example 3. The current carrying capacity of Comparative Examples 1 and 2 is also significantly higher than that of Comparative Example 3, indicating that the separated conductor structure and the uneven surface of the insulated cable do indeed help to increase the current carrying capacity.

[0092] Under low wind speed conditions (≤30m / s), the drag coefficients of Example 1 and Comparative Examples 1 to 3 are not significantly different. However, under high wind speed conditions (>30m / s), the drag coefficient of Example 1 is significantly lower than that of Comparative Examples 1 to 3. The depth and number of recesses have a significant impact on the drag coefficient. When the recess depth is small (Comparative Example 1) or the number of recesses is small (Comparative Example 2), the effect of reducing the drag coefficient is poor, and there is no significant advantage compared to ordinary overhead insulated cables.

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A high current low wind loss aerial cable, characterized in that, The overhead insulated cable comprises a conductor, a conductor shielding layer and an outer insulation layer arranged in sequence from inside to outside; The outer insulation layer comprises a ring body and a plurality of convex portions uniformly and spacedly distributed along the outer periphery of the ring body, and a concave portion is formed between two adjacent convex portions; The convex portion is T-shaped and comprises an outer arc segment, the end of which is connected to the ring body through an upper arc segment and a lower arc segment, and the upper arc segment and the lower arc segment are connected in an S shape; The center of the outer arc segment coincides with the center of the outer diameter circle of the overhead insulated cable, and the radius R of the outer arc segment is half of the outer diameter of the overhead insulated cable; the upper arc segment and the lower arc segment are both semicircular, and the radius of each is r; When the outer diameter of the overhead insulated cable is 20-30 mm, the central angle θ of the outer arc segment is 7.5 degrees, and the radius r is 0.2-0.4 mm; When the outer diameter of the overhead insulated cable is 30-40 mm, the central angle θ of the outer arc segment is 6 degrees, and the radius r is 0.3-0.5 mm; When the outer diameter of the overhead insulated cable is greater than 40 mm, the central angle θ of the outer arc segment is 5 degrees, and the radius r is 0.3-0.5 mm.

2. An overhead power cable according to claim 1, characterised in that The material of the outer insulation layer is cross-linked polyethylene or polypropylene.

3. The overhead power cable of claim 1, wherein, The thickness of the outer insulation layer is 3-5 mm.

4. The overhead power cable of claim 1, wherein, The conductor is of a multi-layer twisted structure, and an inner insulation layer is arranged between each two single wire layers.

5. An overhead power cable according to claim 4, characterised in that The inner insulation layer is an insulation non-woven fabric, and the thickness thereof is 0.3-0.5 mm.

6. The overhead power cable of claim 4, wherein, The twisting directions of adjacent single wire layers are opposite.

7. A process for the production of an aerial insulated cable as claimed in claim 4, characterized in that, The method comprises the following steps: S1, manufacturing a center conductor: a plurality of conductor single wires are twisted according to a 1+6 structure to obtain a center conductor; S2, manufacturing a first inner insulation layer: wrapping a layer of non-woven fabric insulation tape around the outer periphery of the center conductor; S3, manufacturing an outer layer conductor: a plurality of conductor single wires are uniformly distributed and tightly twisted layer by layer on the outer periphery of the first inner insulation layer to form an outer layer conductor; when the number of twisted layers of the outer layer conductor is greater than 2, an inner insulation layer is arranged outside the second single wire layer; S4, using a cable extruder to extrude a conductor shielding layer and an outer insulation layer on the outer surface of the outer layer conductor, and cooling the overhead insulated cable after extrusion molding.

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