A three-in-one composite mid-voltage drum cable with outer stranded ground core conductor

Abstract

A three-in-one composite medium-voltage drum cable with outer stranded ground wire core conductor, comprising a main core, a control core group, a filler core and a composite wire group. The main core, the control core group and the composite wire group are stranded around the axis of the filler core, and then wrapped with an inner sheath, a braided tensile layer and an outer sheath; a plurality of main cores are arranged in axial symmetry; there is one main core between adjacent control core groups and / or between two adjacent control core groups; the structure of the composite wire group is that an optical cable sheath is wrapped outside a layer-stranded optical cable, a ground wire core conductor is concentrically stranded outside the optical cable sheath by a plurality of ground wire strands, a semi-conductive nylon belt is overlapped and wrapped outside the concentrically stranded strands, and a semi-conductive material is wrapped outside the semi-conductive nylon belt to form a ground wire core semi-conductive layer. The structure of the main core is that a conductor shielding layer, an insulation layer and an insulation shielding layer are sequentially wrapped outside the main core conductor from inside to outside. The structure of the control core group is that a control core shielding layer and a control core sheath are sequentially wrapped outside the control core cable core formed by a control core conductor.

Description

Technical Field

[0001] This invention belongs to the field of cable technology, specifically a three-in-one composite medium-voltage drum cable with an outer stranded ground conductor and an outer stranded ground conductor. Background Technology

[0002] Reel cables are mainly used in various mobile reel systems such as port machinery and open-pit mining equipment. They have good wear resistance, resistance to sunlight aging, tensile strength, and flexibility, and can be well applied in various winding and unwinding scenarios. With the continuous development of port machinery requirements, reel cables are increasingly required to have more functions: providing the ability to transmit power, control signals, communication signals, and large amounts of images. Therefore, it is necessary to research a three-in-one reel cable that integrates power transmission, signal transmission, and fiber optic transmission. Summary of the Invention

[0003] To address the problems existing in the prior art, this utility model proposes a three-in-one composite medium-voltage drum cable with an outer stranded ground conductor for optical fiber, comprising a main conductor for transmitting electrical energy, a control core group for transmitting signals, and a filler core. It also includes a composite wire group; the main conductor, control core group, and composite wire group are stranded around the axis of the filler core to form a cable, and then sequentially wrapped with an inner sheath, a braided tensile layer, and an outer sheath, with a cable section diameter ratio not exceeding 9 times; there are multiple main conductors arranged symmetrically along an axis; there is one main conductor between adjacent control core groups and composite wire groups, and / or between two adjacent control core groups;

[0004] The structure of the composite cable group is as follows: a sheath (natural styrene-butadiene material) is wrapped around the stranded optical cable. Multiple ground core strands are concentrically twisted to form a ground core conductor outside the optical cable sheath. A layer of semi-conductive nylon tape is overlapped and wrapped around the concentrically twisted strands, and then a semi-conductive material is wrapped around it to form a ground core semi-conductive layer.

[0005] The structure of the main conductor is as follows: from the inside out, the main conductor is wrapped with a conductor shielding layer, an insulation layer, and an insulation shielding layer.

[0006] The structure of the control core assembly is as follows: outside the control core cable core composed of the control core conductor, the control core shielding layer and the control core sheath are wrapped in sequence;

[0007] The outer diameter of the control core corresponds to the outer diameter of the composite wire assembly.

[0008] Specifically:

[0009] The cross-section of the filler core is a circle with multiple concave saddle-shaped arcs on the outside; the shape of each concave arc corresponds to the cross-sectional shape of the main core, control core group and composite core group respectively, and the main core, control core group and composite core group are in the strip grooves corresponding to the concave arcs.

[0010] In composite wire assemblies, for cross-sectional areas of 25mm²...2 The ground conductor is composed of 22 ground core strands twisted concentrically to the right, with a pitch ratio not exceeding 10.

[0011] Each ground wire core strand is composed of 19 tinned copper wires with a diameter of 0.29mm bundled together in a left-hand direction, with a pitch ratio of no more than 20.

[0012] The overlap rate of the semi-conductive nylon tape wrapping the semi-conductive layer of the ground wire core is not less than 15%.

[0013] In the main core, the conductor shielding layer, the insulation layer, and the insulation shielding layer are a three-layer co-extruded structure;

[0014] The average thickness of the conductor shielding layer is not less than 0.6 mm; the thickness of the insulation layer is in accordance with the insulation layer thickness corresponding to the voltage level specified in GB / T 12706.2; the average thickness of the insulation shield is not less than 0.5 mm; both the conductor shielding layer and the insulation shielding layer are made of semi-conductive materials; the insulation layer is made of ethylene propylene rubber.

[0015] The structure of the control core assembly is as follows: a control core insulation layer is wrapped around the control core conductor to form a control wire core. Multiple control wire cores are twisted together (with a pitch ratio of no more than 12 times) and then overlapped and wrapped with high-temperature polyester tape to form a control core cable core. The control core cable core is woven with tinned copper wire to form a control core shielding layer. The control core shielding layer is wrapped with wrapping tape, and the control core sheath is wrapped around the wrapping tape.

[0016] In the control chip assembly

[0017] The insulation layer of the control core is made of fluoroplastic, and the average thickness of the insulation layer of the control core is not less than 0.4 mm;

[0018] The diameter of the tin-plated copper monofilament in the control core shielding layer is 0.20mm, the braiding angle is between 35° and 60°, and the braiding coverage is not less than 90%.

[0019] The thickness of the control core sheath is 1.0mm to 2.0mm, with the thinnest part not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%; the control core sheath is made of chlorinated polyethylene material.

[0020] The main conductor, ground conductor, and control conductor all use Category 5 tinned copper conductors, which are composed of stranded tinned copper monofilaments.

[0021] The main conductor is formed by twisting multiple tinned copper monofilaments to the left with a twisting pitch ratio of no more than 20, and then twisting multiple strands to the right with a twisting pitch ratio of no more than 10. The main conductor is wrapped with a layer of semi-conductive tape.

[0022] The ground conductor strand is made by twisting multiple tinned copper monofilaments together to the left at a twisting pitch ratio of no more than 20.

[0023] The control core conductor is made of multiple tin-plated copper monofilaments bundled together to the left at a twist ratio of no more than 17 times.

[0024] The tin-plated copper monofilament is an annealed tin-plated copper monofilament with a tin layer thickness ranging from 0.6µm to 0.8µm. The oxygen content of the copper in the annealed tin-plated copper monofilament is no greater than 0.001%, and the volume resistivity of the annealed tin-plated copper monofilament at 20°C is no greater than 0.0177 Ω·mm. 2 / m.

[0025] The inner sheath is made of chlorosulfonated polyethylene; the thickness of the inner sheath is in the range of 1.0mm to 2.0mm, the thinnest part of the inner sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%;

[0026] The inner sheath is covered by a woven tensile layer made of polyester; the polyester is pre-twisted with a weave angle of 55 to 60 degrees.

[0027] The outer sheath is made of chlorosulfonated polyethylene material; the thickness of the outer sheath is in the range of 3.0mm to 4.0mm, the thickness of the thinnest part of the outer sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%.

[0028] Advantages of this invention:

[0029] 1. A ground wire + optical fiber composite cable assembly was added, which solved the problem of no optical fiber cable in the conventional structure.

[0030] 2. A control line group has been added, which solves the problem of the lack of a control line group in the conventional structure.

[0031] 3. Small line groups (such as...) Figure 1 The three groups are all placed on the side of the main core. When the movement is under stress, the main core and the central tensile filler core bear the force, ensuring that the side small groups are under little stress and will not have core breakage problems.

[0032] 4. The ground wire + optical fiber composite structure is adopted, which allows for an additional set of control wire groups. Otherwise, if the ground wire and optical fiber each occupy one side gap of the main core, only one set of control wire groups can be placed. With the ground wire + optical fiber composite structure, only one side gap is occupied, and the remaining two side gaps can hold two sets of control core groups, doubling the number of control cores and solving the cable design problem when there are too many control cores.

[0033] 5. The inner sheath, braided tensile layer, and outer sheath are tightly bonded and do not delaminate, ensuring that the sheath does not delaminate during operation, thus extending the cable's service life. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the radial section of this embodiment;

[0035] In the diagram: 1. Main conductor core, 2. Conductor shielding layer, 3. Insulation layer, 4. Insulation shielding layer, 5. Control conductor core, 6. Control core insulation layer, 7. Control core shielding layer, 8. Control core sheath, 9. Filler core, 10. Stranded optical cable, 11. Optical cable sheath, 12. Ground conductor core, 13. Ground semiconducting layer, 14. Inner sheath, 15. Braided tensile layer, 16. Outer sheath.

[0036] Figure 2 This is a schematic diagram of the cross-section of the filler core. Detailed Implementation

[0037] refer to Figure 1 The technical solution of this embodiment is described as follows:

[0038] A three-in-one composite medium-voltage drum cable with an outer stranded ground conductor for optical fiber includes a main conductor for transmitting electrical energy, a control core group for transmitting signals, and a filler core, as well as a composite wire group. The main conductor, control core group, and composite wire group are stranded around the axis of the filler core 9 to form a cable, and then sequentially wrapped with an inner sheath 14, a braided tensile layer 15, and an outer sheath 16, with a cable pitch ratio not exceeding 9 times. There are multiple main conductors arranged symmetrically along an axis. There is one main conductor between adjacent control core groups and composite wire groups and / or between two adjacent control core groups.

[0039] The structure of the composite line group is as follows: an optical cable sheath 11 is wrapped around the stranded optical cable 10, and a ground core conductor 12 is formed by multiple ground core strands concentrically twisted outside the optical cable sheath. A layer of semi-conductive nylon tape is overlapped and wrapped around the concentrically twisted strands, and then a semi-conductive material is wrapped around it to form a ground core semi-conductive layer 13.

[0040] The structure of the main conductor is as follows: the main conductor 1 is wrapped with conductor shielding layer 2, insulation layer 3 and insulation shielding layer 4 from the inside out;

[0041] The structure of the control core assembly is as follows: outside the control core cable core composed of the control core conductor 5, the control core shielding layer 7 and the control core sheath 8 are wrapped in sequence;

[0042] The outer diameter of the control core corresponds to the outer diameter of the composite wire assembly.

[0043] In this example, the cross-section of the filler core 9 is a circle with multiple concave saddle-shaped arcs on the outside; the shape of each concave arc corresponds to the cross-sectional shape of the main core, control core group and composite core group respectively, and the main core, control core group and composite core group are in the strip grooves corresponding to the concave arcs.

[0044] In this example, in the composite wire assembly, for a cross-sectional area of ​​25mm²...2 The ground conductor is composed of 22 ground core strands twisted concentrically to the right, with a pitch ratio not exceeding 10.

[0045] Each ground wire core strand is composed of 19 tinned copper wires with a diameter of 0.29mm bundled together in a left-hand direction, with a pitch ratio of no more than 20.

[0046] The overlap rate of the semi-conductive nylon tape wrapping of the semi-conductive layer 13 of the ground wire core is not less than 15%.

[0047] In this example, the conductor shielding layer, the insulation layer, and the insulation shielding layer in the main wire core are a three-layer co-extruded structure;

[0048] The average thickness of the conductor shielding layer is not less than 0.6 mm; the thickness of the insulation layer is in accordance with the insulation layer thickness corresponding to the voltage level specified in GB / T 12706.2; the average thickness of the insulation shield is not less than 0.5 mm; both the conductor shielding layer and the insulation shielding layer are made of semi-conductive materials; the insulation layer is made of ethylene propylene rubber.

[0049] In this example, the structure of the control core assembly is as follows: the control core conductor 5 is wrapped with a control core insulation layer 6 to form a control wire core. Multiple control wire cores are twisted together with a pitch ratio of no more than 12 times and then overlapped and wrapped with high-temperature polyester tape to form a control core cable core. The control core cable core is woven with tinned copper wire to form a control core shielding layer 7. The control core shielding layer is wrapped with wrapping tape, and the control core sheath 8 is wrapped around the wrapping tape.

[0050] The control core insulation layer 6 is made of fluoroplastic, and the average thickness of the control core insulation layer is not less than 0.4 mm;

[0051] The single wire diameter of the tinned copper wire in the control core shielding layer 7 is 0.20mm, the braiding angle is between 35° and 60°, and the braiding coverage is not less than 90%.

[0052] The thickness of the control core sleeve 8 is 1.0mm to 2.0mm, and the thickness at the thinnest point is not less than 80% of the nominal value - 0.2mm, with an eccentricity of less than 15%; the control core sleeve is made of chlorinated polyethylene material.

[0053] In this example, the main conductor, ground conductor strands, and control conductor all use Category 5 tinned copper conductors, which are composed of stranded tinned copper monofilaments.

[0054] The main conductor is formed by twisting multiple tinned copper monofilaments to the left with a twisting pitch ratio of no more than 20, and then twisting multiple strands to the right with a twisting pitch ratio of no more than 10. A semi-conductive tape can be wrapped around the main conductor.

[0055] The ground conductor strand is made by twisting multiple tinned copper monofilaments together to the left at a twisting pitch ratio of no more than 20.

[0056] The control core conductor is made of multiple tin-plated copper monofilaments bundled together to the left at a twist ratio of no more than 17 times.

[0057] The tin-plated copper monofilament is an annealed tin-plated copper monofilament with a tin layer thickness ranging from 0.6µm to 0.8µm. The oxygen content of the copper in the annealed tin-plated copper monofilament is no greater than 0.001%, and the volume resistivity of the annealed tin-plated copper monofilament at 20°C is no greater than 0.0177 Ω·mm. 2 / m.

[0058] In this example, the inner sheath is made of chlorosulfonated polyethylene; the thickness of the inner sheath is in the range of 1.0mm to 2.0mm, the thinnest part of the inner sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%;

[0059] The inner sheath is covered by a woven tensile layer made of polyester; the polyester is pre-twisted with a weave angle of 55 to 60 degrees.

[0060] The outer sheath is made of chlorosulfonated polyethylene material; the thickness of the outer sheath is in the range of 3.0mm to 4.0mm, the thickness of the thinnest part of the outer sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%.

[0061] The principle and effects of this technical solution are explained as follows:

[0062] 1. The requirements for tinned copper monofilaments in the main conductor, ground conductor strands, and control conductor are as follows: the tinned copper monofilaments are annealed tinned copper monofilaments, with a tin layer thickness controlled within the range of 0.6–0.8 µm, an oxygen content in the copper of the tinned copper monofilament not exceeding 0.001%, and a volume resistivity at 20℃ not exceeding 0.0177 Ω·mm² / m. To ensure the cable's flexibility, bending performance, and tensile strength, a strand twisting ratio of no more than 20 times and left-hand twisting, or a re-twisted strand twisting ratio of no more than 10 times and right-hand twisting, is required. This also makes the cable easier to move and ensures the cable's operating conditions and lifespan during movement. A tin layer thickness control range of 0.6–0.8 µm, an oxygen content in the copper of the tinned copper monofilament not exceeding 0.001%, and a volume resistivity at 20℃ not exceeding 0.01770 Ω·mm² / m effectively ensure the cable's current carrying capacity and service life, contributing to the long-term use of the cable.

[0063] 2. The main conductor's outer conductor shielding layer, insulation layer, and insulation shield adopt a three-layer co-extrusion structure. The average thickness of the conductor shielding layer is not less than 0.6mm. The cable insulation layer thickness is manufactured according to the insulation layer thickness corresponding to the voltage level specified in GB / T 12706.2, and the average thickness of the insulation shield is not less than 0.5mm. Both the conductor shielding layer and the insulation shield are made of semi-conductive materials, and the insulation layer is made of high-strength ethylene propylene rubber. The above three structural layers are wrapped around the conductor to form the core insulation layer. The three-layer co-extrusion structure ensures the electrical performance of the cable core, and the high-strength ethylene propylene insulation ensures the flexibility and strong tensile strength of the cable core. Compared with cross-linked polyethylene insulation, ethylene propylene insulation has better flexibility.

[0064] 3. The average thickness of the outer insulation layer of the control core conductor is not less than 0.4mm. It is made of high-strength fluoroplastic material. Fluoroplastic ensures the temperature resistance of the control core insulation layer during the production process, avoiding insulation deformation caused by high temperature and high pressure in the production process. At the same time, the high-strength fluoroplastic also increases the tensile strength of the control core to a certain extent. Moreover, under the same electrical performance indicators, compared with ethylene propylene insulation and cross-linked polyethylene insulation, the extrusion thickness of fluoroplastic is thinner. Under the same outer diameter, the number of control cores can be increased by about one-third, which is more in line with actual use.

[0065] 4. Control core cabling shall be carried out in accordance with Appendix Figure 1 The control core assembly is cabled in a right-hand direction with a cable pitch ratio of no more than 12. The cable core is wrapped with high-temperature polyester tape. These structures ensure the flexibility and tightness of the control core assembly on the cable side.

[0066] 5. The control core cable is shielded by tin-plated copper wire braiding. The diameter of the tin-plated copper single wire is 0.20mm, the braiding angle is between 35° and 60°, and the braiding coverage is not less than 90%. This structure not only enhances the tensile strength of the control core group, but also plays the role of electromagnetic shielding, preventing the pulses generated by the power part from affecting the transmission of the current signal of the control core group.

[0067] 6. The outer layer of the braid is wrapped with a wrapping tape to prevent the tin-plated copper wire braid from seeping into the braid during the extrusion and sulfurization of the control core sheath.

[0068] 7. The thickness of the control core sheath varies depending on the cable specifications, and is controlled within the range of 1.0mm to 2.0mm. The thinnest part of the sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%. The sheath is made of high-strength chlorinated polyethylene material. These structures effectively protect the control core, ensure the tightness of the control core structure, and clearly separate the control core from other components, each of which plays a different role.

[0069] 8. The optical cable is a stranded optical cable, and the outer sheath of the optical cable is made of natural styrene-butadiene material with an average thickness of 1.0mm.

[0070] 9. The outer sheath of the optical cable uses multiple ground wire strands concentrically twisted together to form the ground wire conductor (for example, in this case, 22 strands of 19 / 0.29mm tinned copper wires concentrically twisted to the right (this structure is 25mm). 2 The conductor strand structure of the ground wire core has a stranding pitch ratio of no more than 10, and the strand bundle direction is left-handed with a pitch ratio of no more than 20. A layer of semi-conductive nylon tape is overlapped and wrapped around the concentrically stranded strands, with an overlap rate of no less than 15%. The semi-conductive nylon tape is wrapped with semi-conductive material, and the final outer diameter should be equivalent to the outer diameter of the two sets of control core groups.

[0071] The above structure and process ensure that the ground wire and optical cable are integrated into a single internal component. Since this is a mobile cable, the main conductor has no metal shielding layer, leaving no place for leakage current to escape during operation. However, with the ground conductor in the semi-conductive layer, leakage current generated during operation can be discharged through the ground conductor, preventing charge buildup and breakdown. Furthermore, the leakage current is small and will not affect the optical cable wrapped in the ground conductor strands, thus ensuring normal operation. This composite structure effectively avoids mutual interference between components, ensuring cable performance.

[0072] 10. The cable center filler uses a saddle-shaped filler, the specific shape of which is as follows: Figure 2 The width d of the filler core is not less than 1.2mm and not more than 7.5mm, depending on the specifications. The height h is determined by the outer diameter of the main core. The design principle is to expand the main core and increase the three small gaps on the side to ensure that the three gaps on the side can accommodate two sets of control core groups and one set of ground wire + optical cable composite line group respectively, while the side of the line group will not protrude from the cable core area. The saddle-shaped filler core is made of semi-conductive material and reinforced with aramid fiber in the center to improve the tensile strength of the saddle-shaped filler core.

[0073] The filler core made of semi-conductive material can effectively guide leaks generated during cable operation to the ground wire, ensuring the safety performance of the cable. The shape design can effectively stabilize the cable core, ensuring that the main core and ground core do not move radially during high-speed movement, greatly improving the cable's mobility and service life. At the same time, the filler core can increase the outer diameter of the side gaps, allowing for the insertion of control wire groups with larger outer diameters.

[0074] 11. Cable cabling shall be carried out in accordance with Appendix Figure 1 The main core, control core group, ground wire + optical cable composite line group and saddle-shaped filler core are placed in the middle position in sequence, and the cabling direction is right-hand; the cabling section diameter ratio is no more than 9 times, which ensures the flexibility of the cable for moving and use.

[0075] 12. The thickness of the inner sheath varies with the cable specifications and is controlled within the range of 1.0mm to 2.0mm. The thickness of the thinnest part of the inner sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%. The inner sheath is made of high-strength chlorosulfonated polyethylene material.

[0076] 13. The inner sheath is made of polyester woven to form a woven tensile layer. The polyester is pre-twisted to avoid fraying during weaving. The weaving angle is 55-60 degrees.

[0077] The above structure can enhance the overall tensile strength of the cable, improve its protection, and extend its service life during operation.

[0078] 14. The thickness of the outer sheath varies with the cable specifications and is controlled within the range of 3.0mm to 4.0mm. The thickness of the thinnest part of the outer sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%. The outer sheath is made of high-strength chlorosulfonated polyethylene material.

[0079] In this embodiment, in the main conductor core, the conductor shielding material of the conductor shielding layer can be YPJ-35 conductor shielding material provided by Jiangyin Haijiang Polymer Materials Co., Ltd., the insulation shielding material of the insulation shielding layer can be XPB-30A insulation shielding material provided by Jiangsu Shangshang Cable Group New Materials Co., Ltd., and the insulation material of the insulation layer can be XJ-30A high-strength ethylene propylene rubber provided by Jiangsu Shangshang Cable Group New Materials Co., Ltd. The chlorinated polyethylene material used for the control core sheath can be any commercially available cable sheath material. The chlorosulfonated polyethylene material used for the inner and outer sheaths will be the corresponding brand from DuPont, depending on the user's specific requirements for cable protection performance; other brands of similar products may also be used.

[0080] The above structure ensures that the inner and outer sheaths of the cable are tightly bonded and will not delaminate. It makes the inner sheath, braided tensile layer and outer sheath form a whole, ensuring that the sheath will not lift during the cable's movement and making it more suitable for cable movement.

Claims

1. A three-in-one composite medium-voltage drum cable with an outer stranded ground conductor for optical fiber, comprising a main conductor for transmitting electrical energy, a control core assembly for transmitting signals, and filler cores, characterized in that... It also includes composite wire groups; the main wire core, control core group and composite wire group are twisted into a cable around the axis of the filler core and then wrapped with an inner sheath, a braided tensile layer and an outer sheath in sequence, with a cable section diameter ratio of no more than 9 times; there are multiple main wire cores, which are arranged symmetrically on an axis; there is a main wire core between adjacent control core groups and composite wire groups and / or between two adjacent control core groups; The structure of the composite line group is as follows: an optical cable sheath is wrapped around the stranded optical cable, and multiple ground core strands are concentrically twisted to form a ground core conductor outside the optical cable sheath. A layer of semi-conductive nylon tape is overlapped and wrapped around the concentrically twisted strands, and then a semi-conductive material is wrapped to form a ground core semi-conductive layer. The structure of the main conductor is as follows: from the inside out, the main conductor is wrapped with a conductor shielding layer, an insulation layer, and an insulation shielding layer. The structure of the control core assembly is as follows: outside the control core cable core composed of the control core conductor, the control core shielding layer and the control core sheath are wrapped in sequence; The outer diameter of the control core corresponds to the outer diameter of the composite wire assembly.

2. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 1, characterized in that: The cross-section of the filler core is a circle with multiple concave saddle-shaped arcs on the outside; the shape of each concave arc corresponds to the cross-sectional shape of the main core, control core group and composite core group respectively, and the main core, control core group and composite core group are in the strip grooves corresponding to the concave arcs.

3. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 1, characterized in that... In composite wire sets, for cross-sectional areas of 25mm² 2 The ground conductor is composed of 22 ground core strands twisted concentrically to the right, with a pitch ratio not exceeding 10. Each ground wire core strand is composed of 19 tinned copper wires with a diameter of 0.29mm bundled together in a left-hand direction, with a pitch ratio of no more than 20. The overlap rate of the semi-conductive nylon tape wrapping the semi-conductive layer of the ground wire core is not less than 15%.

4. The three-in-one composite medium-voltage drum cable with externally stranded ground conductor as described in claim 1, characterized in that the conductor shielding layer, insulation layer and insulation shielding layer in the main core are three-layer co-extruded structures; The average thickness of the conductor shielding layer is not less than 0.6 mm; the thickness of the insulation layer is in accordance with the insulation layer thickness corresponding to the voltage level specified in GB / T 12706.2; the average thickness of the insulation shield is not less than 0.5 mm; both the conductor shielding layer and the insulation shielding layer are made of semi-conductive materials; the insulation layer is made of ethylene propylene rubber.

5. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 1, characterized in that: The structure of the control core assembly is as follows: the control core conductor is wrapped with a control core insulation layer to form a control wire core. Multiple control wire cores are twisted together with a pitch ratio of no more than 12 times and then overlapped and wrapped with high-temperature polyester tape to form a control core cable core. The control core cable core is woven with tinned copper wire to form a control core shielding layer. The control core shielding layer is wrapped with wrapping tape, and the control core sheath is wrapped outside the wrapping tape.

6. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 5, characterized in that it controls... In the chip, The insulation layer of the control core is made of fluoroplastic, and the average thickness of the insulation layer of the control core is not less than 0.4 mm; The diameter of the tin-plated copper monofilament in the control core shielding layer is 0.20mm, the braiding angle is between 35° and 60°, and the braiding coverage is not less than 90%. The thickness of the control core sheath is 1.0mm to 2.0mm, with the thinnest part not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%; the control core sheath is made of chlorinated polyethylene material.

7. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 1, characterized in that: The main conductor, ground conductor, and control conductor all use Category 5 tinned copper conductors, which are composed of stranded tinned copper monofilaments. The main conductor is formed by twisting multiple tinned copper monofilaments to the left with a twisting pitch ratio of no more than 20, and then twisting multiple strands to the right with a twisting pitch ratio of no more than 10. The main conductor is wrapped with a layer of semi-conductive tape. The ground conductor strand is made by twisting multiple tinned copper monofilaments together to the left at a twisting pitch ratio of no more than 20. The control core conductor is made of multiple tin-plated copper monofilaments bundled together to the left at a twist ratio of no more than 17 times. The tin-plated copper monofilament is an annealed tin-plated copper monofilament with a tin layer thickness ranging from 0.6µm to 0.8µm. The oxygen content of the copper in the annealed tin-plated copper monofilament is no greater than 0.001%, and the volume resistivity of the annealed tin-plated copper monofilament at 20°C is no greater than 0.0177 Ω·mm. 2 / m.

8. The three-in-one composite medium-voltage drum cable with an outer stranded ground conductor as described in claim 1, characterized in that: The inner sheath is made of chlorosulfonated polyethylene; the thickness of the inner sheath is in the range of 1.0mm to 2.0mm, the thinnest part of the inner sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%; The inner sheath is covered by a woven tensile layer made of polyester; the polyester is pre-twisted with a weave angle of 55 to 60 degrees. The outer sheath is made of chlorosulfonated polyethylene material; the thickness of the outer sheath is in the range of 3.0mm to 4.0mm, the thickness of the thinnest part of the outer sheath is not less than 80% of the nominal value - 0.2mm, and the eccentricity is less than 15%.

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