10KV overhead polypropylene insulated cable

Abstract

The invention provides a 10KV overhead polypropylene insulated cable. The insulated cable structurally comprises a steel core, an aluminum stranded wire layer, an insulating layer and a protective layer from inside to outside. The aluminum stranded wire layer is made of 6061 aluminum alloy and surrounds the steel core through a rotary winding process, so that the cable is ensured to have good mechanical strength and conductivity. The insulating layer is mainly made of polypropylene-based resin, so that the electrical insulating property of the cable is enhanced, and the carbon black is used for improving the ultraviolet resistance. The protective layer is made of fluorinated rubber materials and has excellent waterproof and weather-proof characteristics. And an outer processing layer consisting of titanium dioxide and zinc oxide nanoparticles is coated between the insulating layer and the protective layer, so that additional ultraviolet resistance and durability protection are provided. The cable has highly reliable electrical and mechanical properties, and is suitable for high-voltage power transmission in an outdoor environment.

Description

Technical Field

[0001] The invention belongs to the technical field of electric wires and cables, and in particular relates to a 10KV overhead polypropylene insulated cable. Background Art

[0002] As global electricity demand continues to grow, especially in the field of high-voltage power transmission, the performance requirements of power cables are increasing. As a common way of power transmission, overhead cables are widely used in outdoor environments. However, traditional cable materials are prone to aging, insulation damage, and decreased conductivity when facing long-term ultraviolet radiation, severe weather conditions (such as rain and wind), and changes in power load. In addition, due to its low environmental protection, polyvinyl olefin materials cannot be effectively recycled after being discarded, which limits its application in sustainable development. In order to meet these challenges, improving the weather resistance, waterproofness and long-term stability of cables has become a key issue.

[0003] According to the relevant disclosed technologies, the technical solution with publication number CN106009265A proposes a method for preparing a semi-conductive shielding material, by using an insulating layer prepared by an insulating material of polypropylene or ethylene-propylene copolymer to achieve good insulation performance of the cable; the technical solution with publication number KR1020140062566A proposes a solution for making a cable insulation layer using olefin copolymers and carbon nanotubes, thereby achieving good thermal stability and conductivity of the high-voltage cable; the technical solution with publication number EP2196482A1 proposes a technical solution using a vinyl acetate copolymer as a cable insulation layer, so that the manufactured cable has high softness and a longer service life.

[0004] The above technical solutions all propose several technical solutions to enhance the environmental adaptability and service life of cables. However, for the special application scenarios of medium and high voltage overhead cables that are placed outdoors for a long time and exposed to long-term sunlight, the current relevant technologies cannot provide a better solution.

[0005] The foregoing discussion of the background art is intended only to facilitate an understanding of the present invention. This discussion does not acknowledge or admit that any of the material referred to is part of the common general knowledge. Summary of the invention

[0006] The object of the present invention is to provide a 10KV overhead polypropylene insulated cable; the insulated cable structure includes a steel core, an aluminum stranded wire layer, an insulating layer and a protective layer from the inside to the outside. The aluminum stranded wire layer is made of 6061 aluminum alloy and is wound around the steel core through a rotary winding process to ensure that the cable has good mechanical strength and conductivity. The insulating layer is mainly made of polypropylene-based resin to enhance the electrical insulation performance of the cable, wherein carbon black raw materials are mixed in the insulating layer to improve the UV resistance. The protective layer is composed of fluorinated rubber material and has excellent waterproof and weather resistance. An outer treatment layer composed of titanium dioxide and zinc oxide nanoparticles is coated between the insulating layer and the protective layer to provide additional UV resistance and durability protection. The cable has highly reliable electrical and mechanical properties and is suitable for high-voltage power transmission in outdoor environments.

[0007] The present invention adopts the following technical solution: a 10KV overhead polypropylene insulated cable, the cable comprising a steel core (1), an aluminum stranded wire layer (2), an insulating layer (3) and a protective layer (4) from the inside to the outside;

[0008] The main material of the single wire of the aluminum stranded wire layer (2) is 6061 aluminum alloy, and it is wound around the steel core (1) by rotation winding;

[0009] The main material of the insulating layer (3) is polypropylene-based resin;

[0010] Wherein, an outer treatment layer (32) is coated between the insulating layer (3) and the protective layer (4) by a spraying process; the raw material of the outer treatment layer (32) is a mixture of titanium dioxide and zinc oxide nanoparticles;

[0011] Preferably, the number of the aluminum stranded wire layers is 1 to 3; the number of the aluminum stranded wire layers (2) is determined by the rated nominal voltage of the cable;

[0012] Preferably, when the number of the aluminum stranded wire layers (2) is 2 or 3, the winding directions of two adjacent aluminum stranded wire layers (2) are different;

[0013] Preferably, the aluminum wires of the aluminum stranded wire layer (2) meet the following standards: electrical conductivity greater than or equal to 58% IACS, and finished product elongation greater than or equal to 5%;

[0014] Preferably, the insulating layer (3) further comprises 0.5% to 0.8% by mass of carbon black material;

[0015] Preferably, a waterproof layer is provided outside the insulating layer; the material of the waterproof layer is fluorinated rubber;

[0016] Furthermore, a method for preparing a 10KV overhead polypropylene insulated cable is proposed, and the method is applied to preparing the insulated cable; the method comprises the following steps:

[0017] S100: Using a winch machine to twist the aluminum alloy wires around the outer circumference of the steel core (1) to form a semi-finished cable having one or more aluminum stranded wire layers (2);

[0018] S200: performing an immersion treatment on the semi-finished cable obtained in step S100;

[0019] S300: preparing polypropylene-based resin pellets, using an extruder to melt the polypropylene-based resin pellets, and evenly extruding the pellets onto the outside of the aluminum stranded wire layer (2) to form an insulating layer (3);

[0020] S400: Conduct high voltage withstand test on semi-finished cables;

[0021] S500: After passing the test of step S400, the semi-finished cable is insulated and the outer treatment layer (32) is sprayed;

[0022] S600: using an extruder to extrude the semi-finished cable to form a protective layer (4);

[0023] S700: After the cable is air-cooled and shaped, the finished product is inspected;

[0024] Preferably, in step S400, multiple spraying processes are used to spray-form the outer treatment layer (32).

[0025] The beneficial effects achieved by the present invention are:

[0026] 1. The cable of this technical solution uses polypropylene material, which is a thermoplastic material. Different from cross-linked polyethylene, which is a thermosetting material, polypropylene material can be recycled and reused, which is beneficial to resource conservation;

[0027] 2. The cable of this technical solution adds 0.5% to 0.8% of carbon black masterbatch to the insulation layer to increase the anti-ultraviolet and anti-light aging capabilities of the modified polypropylene material and enhance the weather resistance of the insulation;

[0028] 3. The cable of this technical solution further adopts a coating containing titanium dioxide and zinc oxide nanoparticles to be coated on the surface of the insulation layer. Even if the waterproof layer is cracked or softened to a certain extent, it can still resist the invading ultraviolet rays, thereby enhancing the safety and service life of the overhead cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention can be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily drawn to scale, but the emphasis is placed on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0030] Description of the accompanying numbers: 1- steel core; 2- aluminum stranded wire layer; 3- insulation layer; 32- external treatment layer; 4- protective layer;

[0031] Figure 1 is a schematic diagram of the internal structure of the electric wire in an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the internal structure of the composite conductive core in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the steps for manufacturing the electric wire in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with its embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. For those skilled in the art, after reviewing the following detailed description, other systems, methods and / or features of the present embodiment will become apparent. It is intended that all such additional systems, methods, features and advantages are included in this specification. Included within the scope of the present invention and protected by the appended claims. Additional features of the disclosed embodiments are described in the following detailed description, and these features will be apparent from the following detailed description.

[0035] The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right" and the like indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation. The invention is constructed and operated in a specific orientation, so the terms describing the positional relationship in the drawings are only used for exemplary description and cannot be understood as a limitation of this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0036] Embodiment 1: By way of example, a 10KV overhead polypropylene insulated cable is proposed; as shown in the attached Figure 1 As shown, the cable comprises a steel core 1, an aluminum stranded wire layer 2, an insulating layer 3 and a protective layer 4 from the inside to the outside;

[0037] The main material of the single wire of the aluminum stranded wire layer 2 is 6061 aluminum alloy, and it is wound around the steel core 1 by rotation winding;

[0038] The main material of the insulating layer 3 is polypropylene-based resin;

[0039] Wherein, an outer treatment layer 32 is coated between the insulating layer 3 and the protective layer 4 by a spraying process; the raw material of the outer treatment layer 32 is a mixture of titanium dioxide and zinc oxide nanoparticles;

[0040] Preferably, the number of the aluminum stranded wire layers is 1 to 3 layers; the number of the aluminum stranded wire layers 2 is determined by the rated nominal voltage of the cable;

[0041] Preferably, when the number of the aluminum stranded wire layers 2 is 2 or 3, the winding directions of two adjacent aluminum stranded wire layers 2 are different;

[0042] Preferably, the aluminum wires of the aluminum stranded wire layer 2 meet the following standards: electrical conductivity greater than or equal to 58% IACS, and finished product elongation greater than or equal to 5%;

[0043] Preferably, the insulating layer 3 further comprises 0.5% to 0.8% by mass of carbon black material;

[0044] Preferably, a waterproof layer is provided outside the insulating layer; the material of the waterproof layer is fluorinated rubber;

[0045] Further, a method for preparing a 10KV overhead polypropylene insulated cable is proposed, and the method is applied to preparing the insulated cable; Figure 2 As shown, the preparation method comprises the following steps:

[0046] S100: Using a capstan to twist the aluminum alloy wires around the outer circumference of the steel core 1 to form a semi-finished cable having one or more aluminum stranded wire layers 2;

[0047] S200: performing an immersion treatment on the semi-finished cable obtained in step S100;

[0048] S300: preparing polypropylene-based resin pellets, using an extruder to melt the polypropylene-based resin pellets, and evenly extruding them onto the outside of the aluminum stranded wire layer 2 to form an insulating layer 3;

[0049] S400: Conduct high voltage withstand test on semi-finished cables;

[0050] S500: After passing the test of step S400, the semi-finished cable is insulated and the outer treatment layer 32 is sprayed;

[0051] S600: using an extruder to extrude the outer surface of the semi-finished cable to produce a protective layer 4;

[0052] S700: After the cable is air-cooled and shaped, the finished product is inspected;

[0053] Preferably, in step S400, multiple spraying processes are used to spray and form the outer treatment layer 32;

[0054] In a preferred embodiment, in order to obtain a single wire of the aluminum stranded wire, the following process steps are used to prepare the single aluminum wire:

[0055] (1) The aluminum alloy rough wire is subjected to a first drawing process using a wire drawing machine to obtain a semi-finished wire having a diameter not exceeding 6±0.05 mm;

[0056] (2) placing the semi-finished wire in a coiled form into an air furnace and performing heat treatment under atmospheric pressure, wherein the heat treatment temperature is controlled between 270° C. and 300° C. and thermal equilibrium is maintained for 6 to 7 hours to ensure that alloy elements in the aluminum material, such as magnesium and silicon, are uniformly distributed in the crystal structure, thereby improving the plasticity and conductivity of the material;

[0057] (3) taking the semi-finished wire out of the air furnace and cooling it to room temperature at ambient temperature to ensure that the crystal structure of the material is stable;

[0058] (4) further stretching the semi-finished wire to the next process target diameter, and leaving it to stand for 48 hours after each stretching to allow the internal crystal structure of the aluminum wire to be reconstructed and arranged stably;

[0059] By repeating the above steps, the obtained aluminum wire has an average tensile strength of about 200MPa and an elongation of 5%. Its plasticity and toughness are significantly improved to suit the long-term shaking and long overhead laying requirements of high-altitude cables. At the same time, the conductivity of the aluminum wire is increased to 58.5% of the conductivity of annealed copper, and its dielectric properties remain at an excellent level.

[0060] Embodiment 2: This embodiment should be understood to include at least all the features of any of the above embodiments, and further improve upon them;

[0061] In order to cope with the long-term sunlight and high temperature environment that the cable is subjected to under long-term outdoor overhead working conditions, preferably, titanium dioxide TiO2 and zinc oxide ZnO have excellent ultraviolet absorption and scattering capabilities to make a surface treatment coating for the insulating layer 3, which can effectively prevent the material of the insulating layer 3 from aging and degradation under long-term sunlight exposure;

[0062] In a preferred embodiment, the proportion of the ingredients of the outer treatment layer 32 is:

[0063] TiO2, 45% to 50%;

[0064] ZnO, 28%-33%;

[0065] Dispersant, optional, such as polyethylene glycol PEG-400, 8% to 10%;

[0066] Binder, optional, such as polyvinyl alcohol (PVA), 5%;

[0067] Solvent, optional, can be isopropanol or deionized water, 5%;

[0068] In a preferred embodiment, the particle size of the nanoparticles of titanium dioxide is 20 to 50 nm, and the particle size of the nanoparticles of zinc oxide is 30 to 100 nm; particles in the above particle size range can effectively absorb and scatter ultraviolet rays without affecting the transparency or surface properties of the material. In terms of macroscopic effects, they provide better ultraviolet shielding effects, are more evenly distributed, and can better cover the surface of the material;

[0069] TiO2 and ZnO nanoparticles can absorb and scatter UVA and UVB bands, reducing the loss of materials under light; TiO2 mainly acts on short-wave ultraviolet rays, while ZnO can cover a wider ultraviolet band, including long-wave ultraviolet rays, thereby providing more comprehensive ultraviolet protection; It is measured that the UV absorption rate of the outer treatment layer 32 can reach more than 90% in the ultraviolet band range of 200 to 400nm, significantly reducing the probability of ultraviolet rays passing through the cable surface; in long-term accelerated aging tests, the surface of the cable coated with the outer treatment layer 32 can maintain more than 90% of the mechanical strength, which is about 30% higher than the uncoated cable in the control group; after 500 hours of salt spray testing, the cable surface of the outer treatment layer 32 showed extremely low signs of oxidation, showing excellent corrosion resistance;

[0070] In a preferred embodiment, the coating raw material of the outer treatment layer 32 is prepared according to the following manufacturing steps, such as: Figure 3 As shown:

[0071] E100: Prepare nanoparticles of TiO2 and ZnO, and prepare the materials in the above proportions;

[0072] E200: TiO2 and ZnO nanoparticles are added to a solvent, and a dispersant is added to enhance the uniform dispersion of the particles; the mixture is stirred for more than 30 minutes using an ultrasonic disperser or a high shear mixer, and the mixing degree is checked to ensure that the particles are fully dispersed to form a uniform suspension;

[0073] E300: Add the binder to the suspension and continue stirring to make the binder evenly distributed in the mixture;

[0074] E400: Let the suspension stand at room temperature for 1 hour to ensure good dissolution and eliminate bubbles;

[0075] E500: Filter the mixed solution to remove undispersed particles or impurities, and store the prepared nanoparticle suspension in a sealed container for later use;

[0076] Through the above steps, a suspension formulation for forming the outer treatment layer 32 is obtained;

[0077] In a preferred embodiment, the insulation layer 3 is immediately warmed after being extruded from the extrusion die, and the spraying process of the outer treatment layer 32 is performed in the following manner;

[0078] Preferably, an aerosol spray device or an electrostatic spray device is used to spray the outer treatment layer 32 on the surface of the insulating layer 3 to ensure a uniform coating effect; the spraying equipment is required to have the function of accurately controlling the flow rate and the particle injection amount, and can cover the surface of the hot extruded polypropylene material;

[0079] Furthermore, the nozzle diameter is preferably 0.2 to 0.5 mm in diameter, and two or more nozzles may be used to spray uniformly from different directions onto the newly extruded insulating layer 3 or a rotating surrounding spraying process may be used to ensure uniform spraying of the nanoparticles;

[0080] Preferably, the flow rate of the spraying equipment is controlled at 10 to 200 ml / min. According to the specific application requirements, a suitable flow rate control range is selected;

[0081] Preferably, the nanoparticle concentration of the mixture of the outer treatment layer 32 needs to be controlled; preferably, the particle spraying concentration is between 1% and 5% (w / v), and the spraying speed is within 2 to 5 g / min;

[0082] Preferably, a nozzle with a nozzle diameter of 0.2 to 0.5 mm is used to ensure uniform spraying of the nanoparticles; a nozzle that is too large will result in excessive spraying, and a nozzle that is too small may cause clogging; preferably, an air pressure of 0.1 to 0.5 MPa is used for spraying to ensure that the nanoparticles can be evenly distributed on the polypropylene surface and provide sufficient adhesion pressure;

[0083] Preferably, multiple spraying is adopted, and the coating thickness of each spraying is controlled at 10-50 μm to ensure that the nanoparticles form effective penetration outside the insulating layer 3; after multiple layers are processed well, a good anti-ultraviolet protective layer is formed;

[0084] Preferably, the spraying operation is started when the insulating layer 3 is extruded and initially cooled to about 80-100° C.; within this temperature range, the surface of the insulating layer 3 still has sufficient thermal viscosity, which is conducive to the attachment of nanoparticles;

[0085] Preferably, an electrostatic spraying device is used to evenly spray the prepared suspension ingredients on the surface of the insulating layer 3;

[0086] Preferably, after spraying is completed, the surface is slowly cooled to room temperature by air cooling so that the nanoparticles are fixed on the surface and form a stable coating.

[0087] Embodiment 3: This embodiment should be understood to include at least all the features of any of the above embodiments, and further improve upon them;

[0088] In a preferred embodiment, the spraying thickness of the outer treatment layer 32 is further calculated by calculating the sunshine conditions, average temperature and other natural environmental factors for laying the insulated cable;

[0089] Preferably, the total thickness D of the outer treatment layer 32 can be calculated by the following formula:

[0090]

[0091] In the above formula, a uv is the UV resistance of the material, in millimeters per year, indicating the coating thickness required each year to offset the degradation effect of UV rays; in the laboratory, the material is exposed to test using UV accelerated aging equipment (such as a UV irradiation box); by simulating long-term exposure to UV rays, the degradation rate of the material in a natural environment can be predicted in a relatively short period of time; preferably, the test standards that can be used include ASTM G154 (UV accelerated aging test) and ISO 4892 (light aging test for plastics); these standards define specific conditions such as light, temperature, and humidity; and, by regularly measuring the physical thickness or chemical property changes of the material, its UV resistance, such as the thickness of degradation per year, can be determined;

[0092] T sum Tem is the average annual sunshine time in the area where the cables are installed; avg is the annual average temperature;

[0093] UV is the ultraviolet index, which indicates the statistical intensity of ultraviolet rays in the area each year; η is the ultraviolet intensity influence coefficient, which can be specifically set by relevant technical personnel according to the safety and life requirements;

[0094] L is the expected service life of the cable;

[0095] Through the above calculation, the basic coating thickness of the outer treatment layer 32 can be determined to set the specific process parameters of the spraying step.

[0096] Although the present invention has been described above with reference to various embodiments, it should be understood that many changes and modifications may be made without departing from the scope of the present invention. That is, the methods, systems and devices discussed above are examples. Various configurations may appropriately omit, replace or add various processes or components. For example, in alternative configurations, the method may be performed in an order different from the order described, and / or various components may be added, omitted and / or combined. Moreover, the features described with respect to certain configurations may be combined in various other configurations, such as different aspects and elements of the configurations may be combined in a similar manner. In addition, the elements therein may be updated as the technology develops, i.e., many elements are examples and do not limit the scope of the present disclosure or claims.

[0097] Specific details are given in the specification to provide a thorough understanding of the exemplary configurations including implementations. However, the configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary details to avoid obscuring the configurations. This description provides only example configurations and does not limit the scope, applicability, or configurations of the claims. On the contrary, the foregoing description of the configurations will provide those skilled in the art with an enabling description for implementing the described techniques. Various changes may be made to the functions and arrangements of the elements without departing from the spirit or scope of the present disclosure.

[0098] In summary, it is intended that the above detailed description is considered to be illustrative rather than restrictive, and it should be understood that the above embodiments should be understood to be only used to illustrate the present invention and not to limit the scope of protection of the present invention. After reading the contents of the present invention, the technician can make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A 10KV overhead polypropylene insulated cable, characterized in that: The cable comprises, from the inside to the outside, a steel core (1), an aluminum stranded wire layer (2), an insulating layer (3) and a protective layer (4); The main material of the single wire of the aluminum stranded wire layer (2) is 6061 aluminum alloy, and it is wound around the steel core (1) by rotation winding; The main material of the insulating layer (3) is polypropylene-based resin; An outer treatment layer (32) is coated between the insulating layer (3) and the protective layer (4) by a spraying process; the raw material of the outer treatment layer (32) is a mixture of titanium dioxide and zinc oxide nanoparticles.

2. The insulated cable according to claim 1, characterized in that: The number of the aluminum stranded wire layers is 1 to 3; the number of the aluminum stranded wire layers (2) is determined by the rated nominal voltage of the cable.

3. The insulated cable according to claim 2, characterized in that: When the number of the aluminum stranded wire layers (2) is 2 or 3, the winding directions of two adjacent aluminum stranded wire layers (2) are different.

4. The insulated cable according to claim 3, characterized in that: The aluminum wires of the aluminum stranded wire layer (2) meet the following standards: electrical conductivity is greater than or equal to 58% IACS, and finished product elongation is greater than or equal to 5%.

5. The insulated cable according to claim 4, characterized in that: The insulating layer (3) also includes 0.5% to 0.8% by mass of carbon black material.

6. The insulated cable according to claim 5, characterized in that: A waterproof layer is arranged outside the insulating layer; the material of the waterproof layer is fluorinated rubber.

7. A method for preparing a 10KV overhead polypropylene insulated cable, characterized in that: The preparation method is applied to prepare a 10KV overhead polypropylene insulated cable as claimed in claim 6; the preparation method comprises the following steps: S100: Using a winch machine to twist the aluminum alloy wires around the outer circumference of the steel core (1) to form a semi-finished cable having one or more aluminum stranded wire layers (2); S200: performing an immersion treatment on the semi-finished cable obtained in step S100; S300: preparing polypropylene-based resin pellets, using an extruder to melt the polypropylene-based resin pellets, and evenly extruding the pellets onto the outside of the aluminum stranded wire layer (2) to form an insulating layer (3); S400: Conduct high voltage withstand test on semi-finished cables; S500: After passing the test of step S400, the semi-finished cable is insulated and the outer treatment layer (32) is sprayed; S600: using an extruder to extrude the semi-finished cable to form a protective layer (4); S700: After the cable is air-cooled and shaped, it is inspected as a finished product.

8. The preparation method according to claim 7, characterized in that: In step S400, multiple spraying processes are used to spray and form the outer treatment layer (32).

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