Non-crosslinked polyethylene insulated medium-voltage flame-retardant power cable

Abstract

The invention discloses a non-crosslinked polyethylene insulated medium-voltage flame-retardant power cable, and relates to the technical field of cables. The non-crosslinked polyethylene insulated medium-voltage flame-retardant power cable comprises a plurality of insulated wire cores which are arranged together in a pairwise tangent manner, a wrapping layer wrapping the outer sides of the plurality of insulated wire cores, an isolation sleeve wrapping the outer side of the wrapping layer, an armor layer wrapping the outer side of the isolation sleeve, and an outer sheath layer wrapping the outer side of the armor layer, the filling layers are filled among the plurality of insulating wire cores and between the plurality of wire cores and the wrapping layer; each insulating wire core sequentially comprises a conductor, a conductor shielding layer, a non-crosslinked polyethylene insulating layer, an insulating shielding layer and a metal shielding layer from inside to outside.

Description

Technical Field

[0001] The invention relates to a non-cross-linked polyethylene insulated medium-voltage flame-retardant power cable. Background Art

[0002] With the continuous progress and development of human society, the concept of sustainable development has been deeply rooted in people's hearts. Environmental protection has become an issue closely related to human survival and development, and its importance cannot be ignored. In the context of globalization, the rapid development of China's power system is particularly significant. The scale of China's power grid has ranked first in the world, and the demand for cables has reached an unprecedented level. In this context, promoting the sustainable development of the cable industry is not only in line with the requirements of the country's long-term development plan, but also a key link in achieving green economic transformation.

[0003] At present, cross-linked polyethylene (XLPE) is widely used as cable insulation material in power grids in my country and even the world. Although XLPE is favored for its good electrical properties and high temperature resistance, some problems are also exposed in practical applications. First, when these cables reach the end of their service life, due to their complex chemical structure, recycling becomes very difficult, resulting in a large amount of solid waste that cannot be effectively disposed of, causing a burden on the environment. Secondly, the cross-linking process and the subsequent degassing step not only prolong the production cycle, but also greatly increase manufacturing costs and energy consumption, which is obviously contrary to the current concept of energy conservation, carbon reduction and green development.

[0004] In view of this, finding new materials that can replace traditional cross-linked polyethylene has become a common focus of attention within and outside the industry. Non-cross-linked polyolefin materials, with their low processing energy consumption and excellent recyclability, have shown great potential in this field and have gradually become a hot topic of research. In particular, thermoplastic polypropylene (PP) and polyethylene (PE)-based insulation materials are considered to be the main direction of future non-cross-linked cable development. PP has high hardness and brittleness at room temperature due to its high crystallinity; while early PE-based materials based on low-density polyethylene (LDPE) have problems with low melting point and insufficient high-temperature stability.

[0005] The present invention overcomes the above problems by introducing non-cross-linked polyethylene insulation material to prepare a non-cross-linked polyethylene insulated medium-voltage flame-retardant power cable. Summary of the invention

[0006] The object of the present invention is to provide a non-cross-linked polyethylene insulated medium voltage flame-retardant power cable to solve the technical problems mentioned in the above background technology.

[0007] The technical solution for achieving the purpose of the present invention is:

[0008] A non-cross-linked polyethylene insulated medium-voltage flame-retardant power cable, comprising a plurality of insulating cores arranged tangentially in pairs, a sheath wrapped around the outside of the plurality of insulating cores, an isolation sleeve wrapped around the outside of the sheath, an armored layer wrapped around the outside of the isolation sleeve, an outer sheath layer wrapped around the outside of the armored layer, and a filling layer filled between the plurality of insulating cores and between the plurality of cores and the sheath; the insulating core comprises, from the inside to the outside, a conductor, a conductor shielding layer, a non-cross-linked polyethylene insulating layer, an insulating shielding layer, and a metal shielding layer.

[0009] Furthermore, the conductor is formed by twisting a plurality of single-filament conductors; the conductor is any one of the second type of metal-coated annealed copper conductor, non-metal-coated annealed copper conductor, second type of aluminum conductor, and aluminum alloy conductor in accordance with GB / T 3956.

[0010] The present invention adopts any one of the second metal-plated annealed copper conductor, the non-metal-plated annealed copper conductor, the second aluminum conductor, and the aluminum alloy conductor that conforms to GB / T 3956. The prepared cable is more suitable for use in a medium-voltage power transmission system, thereby ensuring the stable operation of the cable.

[0011] Furthermore, the conductor shielding layer is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of the conductor.

[0012] Furthermore, the conductor shielding layer is firstly formed by wrapping a layer of semi-conductive wrapping tape around the conductor, and then extruding a vinyl non-cross-linked semi-conductive shielding material outside the semi-conductive wrapping tape.

[0013] The present invention adds a semiconductive wrapping tape before extruding the vinyl non-crosslinked semiconductive shielding material, which can realize double-layer shielding together with the vinyl non-crosslinked semiconductive shielding material, and on the other hand, makes the conductor more compact and facilitates the extrusion of the vinyl non-crosslinked semiconductive shielding material.

[0014] Furthermore, the thickness of the vinyl non-cross-linked semi-conductive shielding material at any point after extrusion should not be less than 0.6 mm.

[0015] Furthermore, the insulating shielding layer is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of a non-cross-linked polyethylene insulating layer.

[0016] Furthermore, the conductor shielding layer, the non-crosslinked polyethylene insulation layer and the insulation shielding layer adopt a three-layer co-extrusion process to extrude the vinyl non-crosslinked semi-conductive shielding material, the vinyl non-crosslinked insulation material and the vinyl non-crosslinked semi-conductive shielding material outside the conductor at one time.

[0017] The conductor shielding layer, the non-crosslinked polyethylene insulating layer and the insulating shielding layer of the present invention adopt a three-layer co-extrusion process, which can reduce the production process steps and improve production efficiency, closely combine the inner and outer shielding and the main insulation, and improve the initial free discharge voltage.

[0018] Furthermore, in the three-layer co-extrusion process, the extrusion screw temperature of the conductor shielding layer adopts 4 zones, and the temperature of each zone is: 70-80°C in zone 1, 145-155°C in zone 2, 150-160°C in zone 3, 150-160°C in zone 4, and the die head temperature is 160-170°C;

[0019] The extrusion screw temperature of the non-cross-linked polyethylene insulation layer adopts 5 zones, and the temperature of each zone is: Zone 1 100-110℃, Zone 2 150-160℃, Zone 3 170-180℃, Zone 4 170-180℃, Zone 5 170-180℃, and the die head is 180-190℃;

[0020] The extrusion screw temperature of the insulating shielding layer adopts 4 zones, and the temperature of each zone is: 70-80℃ in zone 1, 145-155℃ in zone 2, 150-160℃ in zone 3, 150-160℃ in zone 4, and the head temperature is 160-170℃.

[0021] Furthermore, after the conductor shielding layer, the non-cross-linked polyethylene insulation layer and the insulation shielding layer are co-extruded, they need to be cooled in a vulcanizing tube cooling section and a cooling tube cooling section in sequence.

[0022] Furthermore, the temperature of the cold section of the vulcanization pipe adopts 9 zones, and the temperature of each zone is: zone 1 35-50°C, zone 2 35-50°C, zone 3 80-100°C, zone 4 80-100°C, zone 5 80-100°C, zone 6 60-80°C, zone 7 60-80°C, zone 8 60-80°C, zone 9 60-80°C.

[0023] Furthermore, the metal shielding layer is formed by wrapping a copper tape around the outer surface of the insulating shielding layer.

[0024] Furthermore, the metal shielding layer is firstly wrapped with a layer of semi-conductive Tetoron tape outside the insulating shielding layer, and then wrapped with copper wire shielding; the semi-conductive Tetoron tape plays a role in preventing the copper wire from scratching the insulating core.

[0025] Furthermore, the filling layer is made of parallel stranded PP filling rope, fan-shaped PE filling strip or halogen-free flame-retardant filling rope.

[0026] Furthermore, the wrapping layer adopts halogen-free low-smoke flame-retardant glass cloth tape, which plays the role of flame retardancy and binding at the same time.

[0027] Furthermore, the armor layer adopts tinned steel strip or galvanized steel wire.

[0028] Furthermore, the outer sheath layer adopts flame retardant polyethylene or polyvinyl chloride sheath material.

[0029] By adopting the above technical solution, the present invention has the following beneficial effects:

[0030] (1) The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable of the present invention adopts non-cross-linked polyethylene insulation material to prepare the insulation core. The non-cross-linked polyethylene insulation material is a thermoplastic material, which is environmentally friendly and recyclable, and does not require cross-linking and degassing processes, thereby effectively reducing energy consumption and shortening the production cycle. Compared with traditional polypropylene (PP) insulation materials, non-cross-linked polyethylene not only has a lower extrusion temperature, further reducing energy consumption, but also has better performance in AC and DC electrical properties, mechanical properties, and resistance to water tree and electrical tree aging, avoiding the problems of high hardness and brittleness of PP materials at room temperature and the problem of insufficient high temperature stability of low-density polyethylene (LDPE).

[0031] (2) After the co-extrusion of the conductor shielding layer, the non-cross-linked polyethylene insulation layer and the insulation shielding layer of the present invention, they need to be cooled in a vulcanizing tube cold section and a cooling tube cold section in sequence, and then cooled in two sections. The temperature of each zone in the vulcanizing tube cold section is: 35-50°C for zone 1, 35-50°C for zone 2, 80-100°C for zone 3, 80-100°C for zone 4, 80-100°C for zone 5, 60-80°C for zone 6, 60-80°C for zone 7, 60-80°C for zone 8 and 60-80°C for zone 9. The crystallization of the vinyl non-cross-linked semi-conductive shielding material, the vinyl non-cross-linked insulation material and the vinyl non-cross-linked semi-conductive shielding material is more perfect, and it is not easy to generate internal stress. The internal stress of the obtained insulating wire core is better released, which affects the overall mechanical properties of the cable and the control of insulation eccentricity.

[0032] (3) The temperature of the cold section of the vulcanizing tube of the present invention is divided into 9 zones, and the temperature of each zone is: zone 1 35-50°C, zone 2 35-50°C, zone 3 80-100°C, zone 4 80-100°C, zone 5 80-100°C, zone 6 60-80°C, zone 7 60-80°C, zone 8 60-80°C, zone 9 60-80°C; under the cooling of the 9 zone temperatures, the conductor shielding layer, the non-cross-linked polyethylene insulation layer, and the insulation shielding layer are quickly formed, and the vinyl non-cross-linked semi-conductive shielding material, the vinyl non-cross-linked semi-conductive shielding material, and the vinyl non-cross-linked insulation material are more perfectly crystallized under this cooling process, and it is not easy to generate internal stress to affect the overall mechanical properties of the cable and the control of insulation eccentricity.

[0033] (4) The present invention adopts any one of the second metal-coated annealed copper conductor, the non-metal-coated annealed copper conductor, the second aluminum conductor, and the aluminum alloy conductor that conforms to GB / T 3956. The cable produced is more suitable for use in a medium-voltage power transmission system, thereby ensuring the stable operation of the cable.

[0034] (5) The present invention adds a semi-conductive wrapping tape before extruding the vinyl non-cross-linked semi-conductive shielding material. On the one hand, it can achieve double-layer shielding together with the vinyl non-cross-linked semi-conductive shielding material. On the other hand, it makes the conductor more compact and facilitates the extrusion of the vinyl non-cross-linked semi-conductive shielding material.

[0035] (6) The conductor shielding layer, non-cross-linked polyethylene insulation layer, and insulation shielding layer of the present invention adopt a three-layer co-extrusion process, which can reduce the production process steps and improve production efficiency, and closely combine the layers of the wire core together, making the overall structure more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] The numbers in the accompanying drawings are: conductor 1, conductor shielding layer 2, non-cross-linked polyethylene insulation layer 3, insulation shielding layer 4, metal shielding layer 5, filling layer 6, wrapping layer 7, isolation sleeve 8, armor layer 9, outer sheath layer 10. DETAILED DESCRIPTION

[0039] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the embodiments of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when used, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0044] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present invention is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0045] Overall embodiment

[0046] See Figure 1 A non-cross-linked polyethylene insulated medium-voltage flame-retardant power cable, comprising three insulating cores arranged tangentially in pairs, a sheath 7 wrapped around the outside of multiple insulating cores 1, an isolation sleeve 8 wrapped around the outside of the sheath 7, an armor layer 9 wrapped around the outside of the isolation sleeve 8, an outer sheath layer 10 wrapped around the outside of the armor layer 9, and a filling layer 6 filled between the multiple insulating cores 1 and between the multiple cores and the sheath 7; the insulating core 1 comprises a conductor 1, a conductor shielding layer 2, a non-cross-linked polyethylene insulating layer 3, an insulating shielding layer 4, and a metal shielding layer 5 from the inside to the outside.

[0047] The conductor 1 is formed by twisting a plurality of single-filament conductors; the conductor is any one of the second type of metal-coated annealed copper conductor, non-metal-coated annealed copper conductor, second type of aluminum conductor, and aluminum alloy conductor in accordance with GB / T 3956.

[0048] The conductor shielding layer 2 is formed by extruding a vinyl non-cross-linked semi-conductive shielding material on the outer surface of the conductor 1 .

[0049] The conductor shielding layer 2 is formed by firstly wrapping a layer of semi-conductive wrapping tape around the conductor 1, and then extruding a vinyl non-cross-linked semi-conductive shielding material outside the semi-conductive wrapping tape.

[0050] The thickness of the vinyl non-cross-linked semi-conductive shielding material at any point after extrusion should not be less than 0.60 mm.

[0051] The insulating shielding layer 4 is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of the non-cross-linked polyethylene insulating layer 3 .

[0052] The conductor shielding layer 2, the non-crosslinked polyethylene insulation layer 3 and the insulation shielding layer 4 adopt a three-layer co-extrusion process to extrude vinyl non-crosslinked semi-conductive shielding material, vinyl non-crosslinked insulation material and vinyl non-crosslinked semi-conductive shielding material out of the conductor at one time.

[0053] The three-layer co-extrusion process adopts the multifunctional catenary production line of XLPE and PP cables produced by Finland's Mailafeel Company; the filter adopts a structure in which each piece has its own locked edge. Among them, the insulating filter is selected to be used in 5 layers, with mesh numbers of 20, 78, 156, 78, and 20 respectively; the conductor shielding and insulation shielding filters are selected to be used in 3 layers, with mesh numbers of 20, 78, and 20 respectively.

[0054] The filter can filter out impurities in the material flow, prevent unplasticized vinyl non-cross-linked semi-conductive shielding materials and vinyl non-cross-linked insulating materials from entering the machine head, and at the same time increase the material flow resistance to make it more compact.

[0055] In the three-layer co-extrusion process, the extrusion screw temperature of the conductor shielding layer adopts 4 zones, and the temperature of each zone is: 70-80°C in zone 1, 145-155°C in zone 2, 150-160°C in zone 3, and 150-160°C in zone 4, and the die head temperature is 160-170°C;

[0056] The extrusion screw temperature of the non-cross-linked polyethylene insulation layer 3 adopts 5 zones, and the temperature of each zone is: zone 1 100-110°C, zone 2 150-160°C, zone 3 170-180°C, zone 4 170-180°C, zone 5 170-180°C, and the die head is 180-190°C;

[0057] The extrusion screw temperature of the insulating shielding layer 4 is divided into four zones, each zone having a temperature of: 70-80°C in zone 1, 145-155°C in zone 2, 150-160°C in zone 3, and 150-160°C in zone 4, and the die head temperature is 160-170°C.

[0058] After the three layers of the conductor shielding layer 2, the non-cross-linked polyethylene insulation layer 3 and the insulation shielding layer 4 are co-extruded, they need to be cooled in turn by the vulcanizing tube cold section and the cooling tube cold section, wherein the temperature of the vulcanizing tube cold section adopts 9 zones, and the temperature of each zone is: zone 1 35-50°C, zone 2 35-50°C, zone 3 80-100°C, zone 4 80-100°C, zone 5 80-100°C, zone 6 60-80°C, zone 7 60-80°C, zone 8 60-80°C, zone 9 60-80°C; under the cooling of the 9 zone temperatures, the conductor shielding layer, the non-cross-linked polyethylene insulation layer and the insulation shielding layer are quickly formed, and the vinyl non-cross-linked semi-conductive shielding material, the vinyl non-cross-linked semi-conductive shielding material and the vinyl non-cross-linked insulation material are more perfectly crystallized under this cooling process, and it is not easy to generate internal stress to affect the overall mechanical properties of the cable and the control of insulation eccentricity. The vinyl non-crosslinked insulating material of the invention is prepared by adopting a thermoplastic insulating polyethylene cable material and a preparation method thereof disclosed in Chinese invention patent CN118755181A.

[0059] The metal shielding layer is formed by wrapping a copper tape around the outer surface of the insulating shielding layer.

[0060] The metal shielding layer is firstly wrapped with a layer of semi-conductive Tetoron tape outside the insulating shielding layer, and then wrapped with copper wire shielding; the semi-conductive Tetoron tape plays a role in preventing the copper wire from scratching the insulating wire core.

[0061] The filling layer is made of parallel stranded PP filling rope, fan-shaped PE filling strip or halogen-free flame-retardant filling rope.

[0062] The wrapping layer adopts halogen-free low-smoke flame-retardant glass cloth tape, which plays the role of flame retardancy and binding at the same time.

[0063] The armor layer is made of tinned steel strip or galvanized steel wire.

[0064] The outer sheath layer is made of flame-retardant polyethylene or polyvinyl chloride sheath material.

[0065] Example 1

[0066] See Figure 1 A non-cross-linked polyethylene insulated medium-voltage flame-retardant power cable, comprising three insulating cores arranged tangentially in pairs, a sheath 7 wrapped around the outside of multiple insulating cores 1, an isolation sleeve 8 wrapped around the outside of the sheath 7, an armor layer 9 wrapped around the outside of the isolation sleeve 8, an outer sheath layer 10 wrapped around the outside of the armor layer 9, and a filling layer 6 filled between the multiple insulating cores 1 and between the multiple cores and the sheath 7; the insulating core 1 comprises a conductor 1, a conductor shielding layer 2, a non-cross-linked polyethylene insulating layer 3, an insulating shielding layer 4, and a metal shielding layer 5 from the inside to the outside.

[0067] The conductor 1 is formed by twisting a plurality of single-filament conductors; the conductor is any one of the second type of metal-coated annealed copper conductor, non-metal-coated annealed copper conductor, second type of aluminum conductor, and aluminum alloy conductor in accordance with GB / T 3956.

[0068] The conductor shielding layer 2 is formed by extruding a vinyl non-cross-linked semi-conductive shielding material on the outer surface of the conductor 1

[0069] The conductor shielding layer 2 is formed by firstly wrapping a layer of semi-conductive wrapping tape around the conductor 1, and then extruding a vinyl non-cross-linked semi-conductive shielding material outside the semi-conductive wrapping tape.

[0070] The thickness of the vinyl non-cross-linked semi-conductive shielding material at any point after extrusion should not be less than 0.60 mm.

[0071] The insulating shielding layer 4 is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of the non-cross-linked polyethylene insulating layer 3 .

[0072] The conductor shielding layer 2, the non-crosslinked polyethylene insulation layer 3 and the insulation shielding layer 4 adopt a three-layer co-extrusion process to extrude vinyl non-crosslinked semi-conductive shielding material, vinyl non-crosslinked insulation material and vinyl non-crosslinked semi-conductive shielding material out of the conductor at one time.

[0073] The three-layer co-extrusion process adopts the multifunctional catenary production line of XLPE and PP cables produced by Finland's Mailafeel Company; the filter adopts a structure in which each piece has its own locked edge. Among them, the insulating filter is selected to be used in 5 layers, with mesh numbers of 20, 78, 156, 78, and 20 respectively; the conductor shielding and insulation shielding filters are selected to be used in 3 layers, with mesh numbers of 20, 78, and 20 respectively.

[0074] The filter can filter out impurities in the material flow, prevent unplasticized vinyl non-cross-linked semi-conductive shielding material and vinyl non-cross-linked insulating material from entering the machine head, and at the same time increase the material flow resistance to make it more compact.

[0075] In the three-layer co-extrusion process, the extrusion screw temperature of the conductor shielding layer adopts 4 zones, and the temperature of each zone is: 80°C in zone 1, 150°C in zone 2, 155°C in zone 3, and 155°C in zone 4, and the die head temperature is 160°C;

[0076] The extrusion screw temperature of the non-cross-linked polyethylene insulation layer 3 adopts 5 zones, and the temperature of each zone is: 105°C, 160°C, 175°C, 180°C, 180°C, and the head is 180°C;

[0077] The extrusion screw temperature of the insulating shielding layer 4 is divided into four zones, and the temperature of each zone is: 80°C in zone 1, 150°C in zone 2, 155°C in zone 3, and 155°C in zone 4, and the die head temperature is 160°C.

[0078] After the conductor shielding layer 2, the non-crosslinked polyethylene insulation layer 3, and the insulation shielding layer 4 are co-extruded, they need to be cooled in the vulcanizing tube cold section and the cooling tube cold section in sequence, wherein the temperature of the vulcanizing tube cold section adopts 9 partitions, and the temperature of each partition is: 40°C in the first zone, 40°C in the second zone, 80°C in the third zone, 80°C in the fourth zone, 80°C in the fifth zone, 80°C in the sixth zone, 80°C in the seventh zone, 80°C in the eighth zone, and 80°C in the ninth zone; under the cooling of the 9 partition temperatures, the conductor shielding layer, the non-crosslinked polyethylene insulation layer, and the insulation shielding layer are rapidly formed, and the vinyl non-crosslinked semi-conductive shielding material, the vinyl non-crosslinked semi-conductive shielding material, and the vinyl non-crosslinked insulation material are crystallized more perfectly under this cooling process, and it is not easy to generate internal stress to affect the overall mechanical properties of the cable and the control of insulation eccentricity. The vinyl non-crosslinked insulation material of the present invention is made of a thermoplastic insulation polyethylene cable material and its preparation method disclosed in Chinese invention patent CN118755181A.

[0079] The metal shielding layer is formed by wrapping a copper tape around the outer surface of the insulating shielding layer.

[0080] The metal shielding layer is firstly wrapped with a layer of semi-conductive Tetoron tape outside the insulating shielding layer, and then wrapped with copper wire shielding; the semi-conductive Tetoron tape plays a role in preventing the copper wire from scratching the insulating wire core.

[0081] The filling layer is made of parallel stranded PP filling rope, fan-shaped PE filling strip or halogen-free flame-retardant filling rope.

[0082] The wrapping layer adopts halogen-free low-smoke flame-retardant glass cloth tape, which plays the role of flame retardancy and binding at the same time.

[0083] The armor layer is made of tinned steel strip or galvanized steel wire.

[0084] The outer sheath layer is made of flame-retardant polyethylene or polyvinyl chloride sheath material.

[0085] After testing, the eccentricity of the non-cross-linked polyethylene insulated medium voltage flame retardant power cable was ≤4%, and the elongation at break before aging was measured to be 820%.

[0086] Comparative Example 1

[0087] A medium-voltage flame-retardant power cable comprises three insulating cores arranged tangentially in pairs, a sheath 7 wrapped around the outside of a plurality of insulating cores 1, an isolation sleeve 8 wrapped around the outside of the sheath 7, an armor layer 9 wrapped around the outside of the isolation sleeve 8, an outer sheath layer 10 wrapped around the outside of the armor layer 9, and a filling layer 6 filled between the plurality of insulating cores 1 and between the plurality of cores and the sheath 7; the insulating core 1 comprises, from the inside to the outside, a conductor 1, a conductor shielding layer 2, a PP insulating layer, an insulating shielding layer 4, and a metal shielding layer 5.

[0088] The conductor 1 is formed by twisting a plurality of single-filament conductors; the conductor is any one of the second type of metal-coated annealed copper conductor, non-metal-coated annealed copper conductor, second type of aluminum conductor, and aluminum alloy conductor in accordance with GB / T 3956.

[0089] The conductor shielding layer 2 is formed by extruding a PP cable semi-conductive shielding material on the outer surface of the conductor 1

[0090] The conductor shielding layer 2 is formed by firstly wrapping a layer of semi-conductive wrapping tape around the conductor 1, and then extruding a PP cable semi-conductive shielding material outside the semi-conductive wrapping tape.

[0091] The thickness of the PP cable semi-conductive shielding material at any point after extrusion should not be less than 0.60 mm.

[0092] The insulating shielding layer 4 is formed by extruding a PP cable semi-conductive shielding material onto the outer surface of the PP insulating layer 3 .

[0093] The conductor shielding layer 2, the PP insulating layer and the insulating shielding layer 4 are made of PP cable semi-conductive shielding material, PP cable semi-conductive shielding material and PP cable insulating material by a three-layer co-extrusion process.

[0094] The three-layer co-extrusion process adopts the multifunctional catenary production line of XLPE and PP cables produced by Finland's Mailafell Company; the filter adopts a structure in which each piece has its own locked edge. Among them, the insulating filter is selected to be used in 5 layers, with mesh numbers of 20, 80, 150, 80, and 20 respectively; the conductor shielding and insulation shielding filters are selected to be used in 3 layers, with mesh numbers of 20, 80, and 20 respectively.

[0095] The filter can filter out impurities in the material flow, prevent unplasticized PP cable semi-conductive shielding material, PP cable semi-conductive shielding material, and PP cable from entering the machine head, and at the same time increase the material flow resistance to make it denser.

[0096] In the three-layer co-extrusion process, the extrusion screw temperature of the conductor shielding layer adopts 4 zones, and the temperature of each zone is: 150°C in zone 1, 170°C in zone 2, 190°C in zone 3, 195°C in zone 4, and the die head temperature is 200°C;

[0097] The extrusion screw temperature of the PP insulation layer adopts 5 zones, and the temperature of each zone is: 105℃, 160℃, 175℃, 180℃, 180℃, and the head is 180℃;

[0098] The extrusion screw temperature of the insulating shielding layer 4 is divided into four zones, and the temperature of each zone is: 150°C for zone 1, 170°C for zone 2, 190°C for zone 3, 195°C for zone 4, 195°C for zone 5, and 200°C for the die head.

[0099] After the co-extrusion of the conductor shielding layer 2, the PP insulating layer 3 and the insulating shielding layer 4, they need to be cooled in turn by the vulcanizing tube cold section and the cooling tube cold section. The temperature of the vulcanizing tube cold section adopts 9 zones, and the temperature of each zone is: zone 1 80°C, zone 2 80°C, zone 3 40°C, zone 4 40°C, zone 5 40°C, zone 6 40°C, zone 7 40°C, zone 8 40°C, zone 9 40°C.

[0100] The metal shielding layer is formed by wrapping a copper tape around the outer surface of the insulating shielding layer.

[0101] The metal shielding layer is firstly wrapped with a layer of semi-conductive Tetoron tape outside the insulating shielding layer, and then wrapped with copper wire shielding; the semi-conductive Tetoron tape plays a role in preventing the copper wire from scratching the insulating wire core.

[0102] The filling layer is made of parallel stranded PP filling rope, fan-shaped PE filling strip or halogen-free flame-retardant filling rope.

[0103] The wrapping layer adopts halogen-free low-smoke flame-retardant glass cloth tape, which plays the role of flame retardancy and binding at the same time.

[0104] The armor layer is made of tinned steel strip or galvanized steel wire.

[0105] The outer sheath layer is made of flame-retardant polyethylene or polyvinyl chloride sheath material.

[0106] After testing, the insulation eccentricity of the medium voltage flame retardant power cable under this process was ≤8%, and the elongation at break before aging was measured to be 540%.

[0107] Comparison between Comparative Example 1 and Example 1 shows that Example 1 uses non-cross-linked polyethylene insulation material to prepare a medium-voltage flame-retardant power cable through vulcanization tube cold section cooling and cooling tube cold section cooling compared to the traditional PP insulation material in Comparative Example 1. The insulation eccentricity of the medium-voltage flame-retardant power cable prepared in Example 1 is lower than the insulation eccentricity of the medium-voltage flame-retardant power cable prepared in Comparative Example 1, and the elongation at break of the medium-voltage flame-retardant power cable in Example 1 is much higher than the elongation at break of the comparative document 1. This is because the non-cross-linked polyethylene insulation material in Example 1 is used as The raw material combining process uses vulcanization tube cold section cooling and cooling at both ends of the cooling tube cold section cooling, wherein the temperature of each zone of the vulcanization tube cold section cooling is: zone one 40°C, zone two 40°C, zone three 80°C, zone four 80°C, zone five 80°C, zone six 80°C, zone seven 80°C, zone eight 80°C, zone nine 80°C; the internal stress of the insulating core made of non-cross-linked polyethylene insulation material and at this vulcanization tube cold section cooling temperature is fully released, and the insulation eccentricity of the obtained medium voltage flame-retardant power cable is better controlled and the mechanical properties are also better.

[0108] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-cross-linked polyethylene insulated medium voltage flame-retardant power cable, characterized in that: The invention comprises a plurality of insulating wire cores arranged tangentially in pairs, a sheath (7) wrapped around the outside of the plurality of insulating wire cores, an isolation sleeve (8) wrapped around the outside of the sheath (7), an armor layer (9) wrapped around the outside of the isolation sleeve (8), an outer sheath layer (10) wrapped around the outside of the armor layer (9), and a filling layer (6) filled between the plurality of insulating wire cores and between the plurality of wire cores and the sheath (7); the insulating wire core comprises, from the inside to the outside, a conductor (1), a conductor shielding layer (2), a non-cross-linked polyethylene insulating layer (3), an insulating shielding layer (4), and a metal shielding layer (5).

2. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 1, characterized in that: The conductor (1) is formed by twisting a plurality of single-filament conductors; the conductor is any one of the second type of metal-coated annealed copper conductor, non-metal-coated annealed copper conductor, the second type of aluminum conductor, and the aluminum alloy conductor in accordance with GB / T 3956.

3. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 1, characterized in that: The conductor shielding layer (2) is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of the conductor (1).

4. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 1, characterized in that: The conductor shielding layer (2) is firstly formed by wrapping a layer of semi-conductive wrapping tape around the conductor (1), and then extruding a vinyl non-cross-linked semi-conductive shielding material around the semi-conductive wrapping tape.

5. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 3 or 4, characterized in that: The thickness of the vinyl non-cross-linked semi-conductive shielding material at any point after extrusion should not be less than 0.60 mm.

6. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 1, characterized in that: The insulating shielding layer (4) is formed by extruding a vinyl non-cross-linked semi-conductive shielding material onto the outer surface of a non-cross-linked polyethylene insulating layer (3).

7. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 1, characterized in that: The conductor shielding layer (2), the non-crosslinked polyethylene insulating layer (3), and the insulating shielding layer (4) are formed by a three-layer co-extrusion process to extrude vinyl non-crosslinked semi-conductive shielding material, vinyl non-crosslinked insulating material, and vinyl non-crosslinked semi-conductive shielding material out of the conductor at one time.

8. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 7, characterized in that: In the three-layer co-extrusion process, the extrusion screw temperature of the conductor shielding layer adopts 4 zones, and the temperature of each zone is: 70-80°C in zone 1, 145-155°C in zone 2, 150-160°C in zone 3, and 150-160°C in zone 4, and the die head temperature is 160-170°C; The extrusion screw temperature of the non-cross-linked polyethylene insulation layer (3) is divided into five zones, and the temperature of each zone is: zone 1 100-110°C, zone 2 150-160°C, zone 3 170-180°C, zone 4 170-180°C, zone 5 170-180°C, and the die head is 180-190°C; The extrusion screw temperature of the insulating shielding layer (4) is divided into four zones, and the temperature of each zone is: 70-80°C in zone one, 145-155°C in zone two, 150-160°C in zone three, and 150-160°C in zone four, and the die head temperature is 160-170°C.

9. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 8, characterized in that: After the conductor shielding layer (2), the non-cross-linked polyethylene insulation layer (3) and the insulation shielding layer (4) are co-extruded, they need to be cooled in a vulcanizing tube cooling section and a cooling tube cooling section in sequence.

10. The non-cross-linked polyethylene insulated medium voltage flame-retardant power cable according to claim 9, characterized in that: The temperature of the cold section of the vulcanization pipe adopts 9 zones, and the temperature of each zone is: zone 1 35-50°C, zone 2 35-50°C, zone 3 80-100°C, zone 4 80-100°C, zone 5 80-100°C, zone 6 60-80°C, zone 7 60-80°C, zone 8 60-80°C, zone 9 60-80°C.

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