Polypropylene insulated submarine cable

Abstract

The utility model relates to a polypropylene insulation submarine cable. The polypropylene insulation submarine cable comprises three wire cores which are tangent in pairs, and further comprises an inner sheath, an outer polypropylene insulation layer, an outer shielding layer and an outer sheath which are sequentially arranged on the outer sides of the three wire cores from inside to outside, the cable core comprises a conductor, an inner shielding layer wrapping the outer side of the conductor, an inner polypropylene insulating layer wrapping the outer side of the inner shielding layer and a polyethylene sheath wrapping the outer side of the inner polypropylene insulating layer, and the conductor is formed by twisting a plurality of single crystal copper wires. And fillers are respectively filled among the three wire cores and between the inner sheath and the wire cores. According to the submarine cable with the polypropylene insulating layers, the inner polypropylene insulating layer and the outer polypropylene insulating layer are arranged to replace a cross-linked polyethylene insulating layer, so that the cost is reduced, and the quality of the insulating layers is improved. And the inner polypropylene insulating layer and the outer polypropylene insulating layer can be recycled, so that the cable is more environment-friendly.

Description

Technical Field

[0001] The utility model belongs to the technical field of cables, and in particular relates to a polypropylene insulated submarine cable. Background Art

[0002] Wires and cables are called the "arteries" and "nerves" of the national economy, and their products are widely used in the fields of construction, transportation, power plants, automobiles, petrochemicals, etc. The current mainstream main insulation material of power cables is cross-linked polyethylene. However, the current maximum operating temperature of cross-linked polyethylene cables is 70°C and the maximum voltage is 500kV, which cannot meet the requirements of the draft high-voltage and large-capacity power transmission regulations in my country for a maximum operating temperature of 90°C and a maximum design voltage of 800kV, and cannot meet the power requirements under extreme conditions.

[0003] The working temperature of polypropylene is significantly higher than that of cross-linked polyethylene. The breakdown strength is mostly 400kV / mm. The long-term use temperature can reach 100℃, and it has excellent electrical, mechanical and heat resistance properties. The service life of cross-linked polyethylene cables in my country is stipulated to be 30 years, and it is generally less than 20 years in operation. However, as a thermosetting material, cross-linked polyethylene cannot be directly recycled and reused. Such a huge amount of organic matter can only be incinerated and landfilled, which will cause a great waste of resources. Polypropylene is a thermoplastic material that can be recycled and reused, and the raw materials are abundant and cheap. In addition, compared with cross-linked polyethylene cables, polypropylene cables have other advantages such as no need for cross-linking, relatively simple production process, no cross-linking by-products, and can reduce charge accumulation. In short, as a cable insulation material, polypropylene can better meet the requirements of high-voltage and large-capacity power transmission, reduce cable costs, and conform to the development concept and value orientation of green environmental protection. Whether it is used in AC cables or DC cables, it has great development potential. Its feasibility as the main insulation material for power cables has attracted the attention of researchers at home and abroad. Polypropylene has great potential engineering application value as the main insulation material for cables, and is one of the important directions for the development of main insulation materials for cables in my country.

[0004] Submarine cables are cables laid on the seabed and underwater in rivers, and are divided into submarine communication cables and submarine power cables. Submarine cables are immersed in seawater for a long time and need to have good insulation performance. It is necessary to provide a polypropylene insulated submarine cable. Utility Model Content

[0005] In order to achieve the above object, the utility model provides a polypropylene insulated submarine cable.

[0006] The technical solution of a polypropylene insulated submarine cable of the utility model is:

[0007] A polypropylene insulated submarine cable comprises three wire cores tangent to each other in pairs, and also comprises an inner sheath, an outer polypropylene insulation layer, an outer shielding layer, and an outer sheath which are sequentially arranged on the outside of the three wire cores from the inside to the outside, the wire core comprises a conductor, an inner shielding layer wrapped on the outside of the conductor, an inner polypropylene insulation layer wrapped on the outside of the inner shielding layer, and a polyethylene sheath wrapped on the outside of the inner polypropylene insulation layer, the conductor is twisted by a plurality of single crystal copper wires, and fillers are respectively filled between the three wire cores and between the inner sheath and the wire cores.

[0008] Furthermore, the inner shielding layer is made of metal foil, and the outer shielding layer is a copper wire braided shielding layer made of copper wire.

[0009] Furthermore, the filler is PP filling rope.

[0010] Furthermore, the inner sheath is made of cross-linked low-smoke halogen-free flame-retardant polyolefin, and the outer sheath is made of halogen-free flame-retardant nylon.

[0011] Furthermore, the three wire cores are tangent to the inner sheath respectively.

[0012] The utility model provides a polypropylene insulated submarine cable, which has the following advantages compared with the prior art:

[0013] The polypropylene insulation layer submarine cable of the utility model replaces the cross-linked polyethylene insulation layer by providing an inner polypropylene insulation layer and an outer polypropylene insulation layer, thereby reducing the cost and improving the quality of the insulation layer. Both the inner polypropylene insulation layer and the outer polypropylene insulation layer can be recycled and reused, which is more environmentally friendly.

[0014] In the polypropylene insulated submarine cable of the utility model, the conductor of the core is formed by twisting a plurality of single crystal copper wires. The single crystal copper is a conductor manufactured by "high temperature hot casting mode continuous casting method". Because the casting process is subjected to special heating treatment, a single crystal copper conductor can be obtained, which has no grain boundary inside. When the signal is transmitted, there is no need to pass through the "grain boundary" between the grains, and the signal is easier to penetrate and conduct. Since the transmission impedance is reduced, the loss is extremely low, the frequency response characteristics are good, and the conductivity is high, which solves the technical problem of lossless transmission of high-frequency signals. In addition, the single crystal copper has a dense directional solidification structure, which eliminates the transverse grain boundary and has few casting defects such as shrinkage cavities and pores; and the crystallization direction is the same as the wire drawing direction, which can withstand greater plastic deformation. The conductor structure adopts a bundle of multiple thin conductors twisted structure. The twisted conductor is soft, easy to bend, and has extremely high toughness, which is convenient for installation and laying.

[0015] The polypropylene insulated submarine cable of the utility model adopts a two-layer sheath structure by setting an inner sheath and an outer sheath. The material of the inner sheath is a heat-resistant 150°C irradiation cross-linked low-smoke halogen-free flame-retardant polyolefin sheath material. The sheath is irradiated and cross-linked after extrusion, and the physical and mechanical properties and electrical properties are significantly improved. The temperature resistance level can reach up to 150 degrees, and the service life is longer. The outer sheath material is halogen-free flame-retardant nylon. The nylon material itself has a high melting point and good high temperature resistance. At the same time, the sheath has high mechanical strength, strong wear resistance, excellent self-lubrication, and a small friction coefficient, which makes it convenient to lay small-diameter wires through pipes, improves work efficiency, and brings convenience and economy to installation and laying. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a polypropylene insulated submarine cable of the utility model;

[0017] Figure 2 It is a schematic diagram of the structure of the core of the polypropylene insulated submarine cable of the utility model;

[0018] Numbers in the figure: 1, wire core; 2, inner sheath; 3, outer polypropylene insulation layer; 4, outer shielding layer; 5, outer sheath; 6, filler; 7, conductor; 8, inner shielding layer; 9, inner polypropylene insulation layer; 10, polyethylene sheath. DETAILED DESCRIPTION

[0019] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods:

[0020] The specific embodiment of the polypropylene insulated submarine cable of the utility model is as follows: Figure 1 , Figure 2 As shown, it includes three tangent cores 1, and also includes an inner sheath 2, an outer polypropylene insulation layer 3, an outer shielding layer 4, and an outer sheath 5 arranged on the outside of the three cores 1 from the inside to the outside. The core 1 includes a conductor 7, an inner shielding layer 8 wrapped on the outside of the conductor 7, an inner polypropylene insulation layer 9 wrapped on the outside of the inner shielding layer 8, and a polyethylene sheath 10 wrapped on the outside of the inner polypropylene insulation layer 9. The conductor 7 is twisted by multiple single crystal copper wires, and fillers 6 are filled between the three cores 1 and between the inner sheath 2 and the core 1.

[0021] The inner shielding layer 8 is made of metal foil, and the outer shielding layer 4 is a copper wire braided shielding layer made of copper wire. The filler 6 is a PP filling rope. The inner sheath 2 is made of cross-linked low-smoke halogen-free flame-retardant polyolefin, and the outer sheath 5 is made of halogen-free flame-retardant nylon. The three cores 1 are tangent to the inner sheath 2 respectively.

[0022] The polypropylene insulation layer submarine cable of the utility model replaces the cross-linked polyethylene insulation layer by providing an inner polypropylene insulation layer 9 and an outer polypropylene insulation layer 3, thereby reducing the cost and improving the quality of the insulation layer. The inner polypropylene insulation layer 9 and the outer polypropylene insulation layer 3 can be recycled and reused, which is more environmentally friendly.

[0023] In the polypropylene insulated submarine cable of the utility model, the conductor 7 of the core 1 is twisted by multiple single crystal copper wires, and the single crystal copper is the conductor 7 manufactured by the "high temperature hot casting mode continuous casting method". Because the casting process is subjected to special heating treatment, a single crystal copper conductor 7 can be obtained, which has no grain boundary inside. When the signal is transmitted, there is no need to pass through the "grain boundary" between the grains, and the signal is easier to penetrate and conduct. Since the transmission impedance is reduced, the loss is extremely low, the frequency response characteristics are good, and the conductivity is high, which solves the technical problem of lossless transmission of high-frequency signals. In addition, the single crystal copper has a dense directional solidification structure, eliminates the transverse grain boundary, and has few casting defects such as shrinkage holes and pores; and the crystallization direction and the wire drawing direction are the same, which can withstand greater plastic deformation. The conductor 7 structure adopts a bundle twisted structure of multiple thin conductors 7. The twisted conductor 7 is soft, easy to bend, and has extremely high toughness, which is convenient for installation and laying.

[0024] The polypropylene insulated submarine cable of the utility model adopts a two-layer sheath structure by setting an inner sheath 2 and an outer sheath 5. The material of the inner sheath 2 is a heat-resistant 150°C irradiation cross-linked low-smoke halogen-free flame-retardant polyolefin sheath material. After the sheath is extruded, it is irradiated and cross-linked to modify the physical and mechanical properties and electrical properties. The temperature resistance level can reach up to 150 degrees, and the service life is longer. The outer sheath material is halogen-free flame-retardant nylon. The nylon material itself has a high melting point and good high temperature resistance. At the same time, the sheath has high mechanical strength, strong wear resistance, excellent self-lubrication, and a small friction coefficient, which makes it convenient to lay small-diameter wires through pipes, improves work efficiency, and brings convenience and economy to installation and laying.

[0025] The above description is only a preferred 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 polypropylene insulated submarine cable, characterized in that: The invention comprises three wire cores which are tangent to each other in pairs, and also comprises an inner sheath, an outer polypropylene insulation layer, an outer shielding layer, and an outer sheath which are arranged on the outside of the three wire cores in sequence from the inside to the outside. The wire core comprises a conductor, an inner shielding layer wrapped on the outside of the conductor, an inner polypropylene insulation layer wrapped on the outside of the inner shielding layer, and a polyethylene sheath wrapped on the outside of the inner polypropylene insulation layer. The conductor is twisted by multiple single crystal copper wires. Fillers are filled between the three wire cores and between the inner sheath and the wire cores.

2. The polypropylene insulated submarine cable according to claim 1, characterized in that: The inner shielding layer is made of metal foil, and the outer shielding layer is a copper wire braided shielding layer made of copper wire.

3. The polypropylene insulated submarine cable according to claim 1, characterized in that: The filler is PP filling rope.

4. The polypropylene insulated submarine cable according to claim 3, characterized in that: The inner sheath is made of cross-linked low-smoke halogen-free flame-retardant polyolefin, and the outer sheath is made of halogen-free flame-retardant nylon.

5. The polypropylene insulated submarine cable according to claim 1, characterized in that: The three wire cores are tangent to the inner sheath respectively.

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