Two-core direct current cable

Abstract

The utility model discloses a two-core DC cable, which comprises a cable core, a filling strip, a buffer layer, an inner cushion layer, an anti-seismic layer, an armor layer and an outer sheath, the cable core comprises two parallel equal-radius cable core monomers, the outer layer of the cable core is sequentially provided with the buffer layer, the inner cushion layer, the anti-seismic layer, the armor layer and the outer sheath, and the filling strip is arranged between the cable core and the buffer layer; each cable core single body is provided with a conductor, a wrapping semi-conductive layer and an insulating layer which are arranged from inside to outside, the outer layer of each insulating layer is provided with tooth-shaped protrusions, and protruding table tops which abut against each other are arranged at the contact positions of the tooth-shaped protrusions of the two cable core single bodies. According to the utility model, the two cable core monomers adopt a non-twisting design, the cable core length is small, the resistance is small, and the current-carrying capability is stronger; according to the utility model, the outer layer of the insulating layer is provided with the tooth-shaped protrusions and the protruding table-boards which are abutted against the tooth-shaped protrusions, so that space charges on the insulating surface can be effectively reduced, gaps among the tooth-shaped protrusions can form air bands which are beneficial to heat dissipation, rapid degradation of the insulating layer is avoided, and the service life of the direct-current cable is prolonged.

Description

Technical Field

[0001] The utility model relates to a two-core DC cable, belonging to the technical field of cables. Background Art

[0002] DC cables are important devices in the field of modern energy transportation. Compared with AC cables, they have the characteristics of high breakdown voltage and low loss, which has significant advantages in long-distance power transmission. The loss of DC cables mainly comes from the DC resistance of the conductor itself and the aging loss of the insulating material under long-term DC voltage. Regarding the aging loss of insulating materials, studies have shown that it is related to the electric field and temperature of the cable insulation layer. Since the insulation temperature is high inside and low outside, the combined effect causes the electric field strength on the insulation surface to be high, which ultimately leads to the accumulation of space charge on the surface, causing insulation degradation; in order to solve the problem of aging loss of DC cables, it is urgent to design a cable structure that can reduce space charge accumulation and electric field distortion, and improve insulation safety and current carrying capacity. Utility Model Content

[0003] The utility model aims to provide a two-core DC cable to solve the problem of DC cable insulation aging.

[0004] The technical solution to achieve the purpose of the utility model is: a two-core DC cable, including a cable core, a filling strip, a buffer layer, an inner cushion layer, an anti-seismic layer, an armor layer and an outer sheath, the cable core includes two parallel cable core monomers with equal radius, the outer layer of the cable core is sequentially provided with a buffer layer, an inner cushion layer, an anti-seismic layer, an armor layer and an outer sheath, and the filling strip is arranged between the cable core and the buffer layer;

[0005] The cable core monomer has a conductor, a wrapped semiconductive layer and an insulating layer arranged from inside to outside, the outer layer of the insulating layer is a tooth-shaped protrusion, and the contacting positions of the tooth-shaped protrusions of the two cable core monomers are provided with protruding surfaces abutting against each other.

[0006] The utility model adopts a parallel structure design between the two cable core monomers, and the cable core monomers are not twisted. The cable core length in the cable of equal length is the smallest, the resistance is small, and the current carrying capacity is stronger. The utility model also arranges tooth-like protrusions and abutting protruding table surfaces on the outer layer of the insulation layer, which can effectively reduce the space charge on the insulation surface, and the gaps between the tooth-like protrusions can also form an air belt that is conducive to heat dissipation, effectively avoiding rapid degradation of insulation, and is conducive to extending the life of the DC cable.

[0007] The conductor includes a circular stranded conductor and a parallel strip conductor arranged on the outer layer of the circular stranded conductor. The circular stranded conductor is obtained by twisting and pressing multiple strands of copper wire or aluminum wire. The strip conductor is an arc tile structure and is closely fitted with the circular stranded conductor. This structure is conducive to reducing the outer dimensions of the conductor. The surface of the outer strip conductor is smooth, which is conducive to improving the electric field distribution in the insulation layer.

[0008] The insulating layer includes a first insulating layer, a second insulating layer, and a third insulating layer arranged from the inside to the outside. The insulating layer material is polyethylene. The polyethylene crystallinity of the first insulating layer, the second insulating layer, and the third insulating layer decreases successively, which is beneficial to reducing the external electric field of the insulating layer in the radial direction and improving the safety of insulation.

[0009] In order to improve the heat resistance and electrical insulation of the filling strip, the filling strip is made of a vulcanized EPDM rubber strip, which is in close contact with the tooth-like protrusions and the protruding table surface.

[0010] In order to avoid an increase in conductor resistance due to excessive compression, the compression coefficient of the circular stranded conductor is controlled to be 0.86-0.92, and the thickness of the strip conductor is not less than 2 mm.

[0011] In order to reduce the mutual inductance effect between the cable core monomers, the height of the protruding platform is greater than the height of the tooth-like protrusions.

[0012] In order to control the resistivity of the insulating layer and reduce the size of the cable, the first insulating layer and the second insulating layer are prepared by a double-layer co-extrusion process. The thickness of the first insulating layer is 0.8-1.2 mm, and the thickness ratio between the first insulating layer and the second insulating layer is 2:3.

[0013] In order to form a stable air insulation layer outside the third insulation layer, the third insulation layer includes a base layer, a tooth-like protrusion and a protruding surface arranged on the outer layer of the second insulation layer and parallel to the second insulation layer. The tooth-like protrusion and the protruding surface are arranged outside the base layer. The tooth-like protrusion is conical, and its root radius is smaller than the top radius.

[0014] By adopting the above technical solution, the utility model has the following beneficial effects:

[0015] (1) The two cable core monomers of the utility model adopt a parallel structure design, and the cable core monomers are twisted together. The cable core length in the cable of equal length is the smallest, the resistance is small, and the current carrying capacity is stronger. The utility model also provides tooth-like protrusions and abutting protruding surfaces on the outer layer of the insulation layer, which can effectively reduce the space charge on the insulation surface. The gaps between the tooth-like protrusions can also form an air belt that is conducive to heat dissipation, effectively avoiding rapid degradation of insulation, and helping to extend the life of the DC cable.

[0016] (2) The conductor of the utility model is a combination of a circular stranded conductor and a tile-shaped strip conductor. This structure is beneficial to reducing the external dimensions of the conductor. The surface of the outer strip conductor is smooth, which is beneficial to improving the electric field distribution in the insulating layer.

[0017] (3) The insulating layers of the present invention are arranged in layers, and the crystallinity of each insulating layer decreases from the inside to the outside, which can reduce the external electric field of the insulating layer in the radial direction and improve the safety of insulation.

[0018] (4) The filling strip of the utility model is made of vulcanized EPDM rubber strip material, which has good heat resistance and electrical insulation.

[0019] (5) The utility model strictly controls the compression coefficient of the circular stranded conductor, effectively avoiding the increase of the conductor resistance value caused by excessive compression.

[0020] (6) The height of the protruding platform of the utility model is greater than the height of the tooth-like protrusions, thereby reducing the mutual inductance effect between the cable core monomers.

[0021] (7) The utility model controls the thickness relationship between the insulating layers and adopts a double-layer co-extrusion process for production, thereby controlling the resistivity of the insulating layer and reducing the size of the cable.

[0022] (8) The utility model is provided with tooth-like protrusions and a protruding table surface, and the tooth-like protrusions are set to be conical and the root radius thereof is limited to be smaller than the top radius, so that a stable air insulation layer is formed outside the third insulating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the content of the utility model easier to understand, the utility model is further described in detail according to specific embodiments and in conjunction with the accompanying drawings.

[0024] Figure 1 It is a structural schematic diagram of the utility model;

[0025] Figure 2 This is a schematic diagram of the first insulating layer of the utility model;

[0026] The reference numerals in the accompanying drawings are:

[0027] Cable core 1, cable core monomer 11, conductor 111, round stranded conductor 1111, strip conductor 1112, wrapped semi-conductive layer 112, insulating layer 113, first insulating layer 1131, second insulating layer 1132, third insulating layer 1133, tooth-like protrusions 11331, protruding table 11332, filling strip 2, buffer layer 3, inner cushion layer 4, seismic resistant layer 5, armor layer 6, outer sheath 7. DETAILED DESCRIPTION

[0028] 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.

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] 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 present invention to be protected, 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.

[0031] 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.

[0032] In the description of the embodiments of the present utility model, 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 utility model product is conventionally placed when in use, 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 utility model 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 utility model.

[0033] In the description of the embodiments of the present utility model, it is also necessary to explain that, unless otherwise clearly stipulated 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 utility model can be understood according to specific circumstances. The utility model 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 utility model, and cannot be used to limit the scope of protection of the utility model.

[0034] (Example 1)

[0035] See Figure 1 and Figure 2A two-core DC cable of this embodiment comprises a cable core 1, a filling strip 2, a buffer layer 3, an inner cushion layer 4, an anti-seismic layer 5, an armor layer 6 and an outer sheath 7, wherein the cable core 1 comprises two parallel cable core monomers 11 of equal radius, and the outer layer of the cable core 1 is sequentially provided with a buffer layer 3, an inner cushion layer 4, an anti-seismic layer 5, an armor layer 6 and an outer sheath 7, and the filling strip 2 is arranged between the cable core 1 and the buffer layer 3;

[0036] The cable core monomer 11 has a conductor 111, a wrapped semiconductive layer 112 and an insulating layer 113 arranged from inside to outside. The outer layer of the insulating layer 113 is a tooth-like protrusion 1131. The contact between the tooth-like protrusions 1131 of the two cable core monomers 11 is provided with a protruding surface 1132 abutting against each other.

[0037] The height of the protruding platform 1132 is greater than the height of the tooth-like protrusion 1131 .

[0038] The insulating layer 113 includes a first insulating layer 1131, a second insulating layer 1132, and a third insulating layer 1133 arranged from inside to outside. The insulating layer 113 is made of polyethylene, and the crystallinity of the polyethylene in the first insulating layer 1131, the second insulating layer 1132, and the third insulating layer 1133 decreases in sequence.

[0039] The conductor 111 includes a circular stranded conductor 1111 and a parallel strip conductor 1112 arranged on the outer layer of the circular stranded conductor 1111. The circular stranded conductor 1111 is obtained by twisting and pressing multiple strands of copper wire or aluminum wire. The strip conductor 1112 is an arc-shaped tile structure and is tightly fitted with the circular stranded conductor 1111.

[0040] The filling strip 2 is made of vulcanized EPDM rubber strip, which is in close contact with the tooth-like protrusions 1131 and the protruding surface 1132. The vulcanization degree of the EPDM rubber strip is 60%-70%.

[0041] The third insulating layer 1133 includes a base layer, a tooth-like protrusion 1131 and a protruding surface 1132 arranged on the outer layer of the second insulating layer 1132 and parallel to the second insulating layer 1132. The tooth-like protrusion 1131 and the protruding surface 1132 are arranged outside the base layer. The tooth-like protrusion 1131 is conical, and its root radius is smaller than the top radius.

[0042] Specifically, the thickness of the base layer is 0.6-1.0mm, the height of the multiple tooth-like protrusions 1131 is 0.8-1.2mm, the top is 0.1mm wider than the root, which is 0.8-1.0mm, the height of the protruding table 1132 is 4-5mm, the width is 8-10mm, and it is arc-shaped in the height direction, and the corresponding radius is greater than 40mm.

[0043] The compression coefficient of the circular stranded conductor 1111 is 0.86-0.92, and the thickness of the strip conductor 1112 is not less than 2 mm.

[0044] The first insulating layer 1131 and the second insulating layer 1132 are prepared by a double-layer co-extrusion process. The thickness of the first insulating layer 1131 is 0.8-1.2 mm, the thickness of the second insulating layer is 1.2-1.8 mm, and the thickness ratio between the first insulating layer 1131 and the second insulating layer 1132 is 2:3.

[0045] The wrapped semi-conductive layer 112 has a thickness of 0.10-0.15 mm and an overlap rate of 30%.

[0046] The thickness of the inner cushion layer 4 is not less than 0.8mm, the thickness of the anti-seismic layer 5 is not less than 1.0mm, the armor layer 6 is made of double-layer steel belt gap wrapped, the thickness of the steel belt is not less than 0.2mm, which can withstand external forces and protect the internal structure of the cable. The outer sheath 7 is made of linear low-density polyethylene, which has waterproof and protective effects, and the thickness of the outer sheath 7 is not less than 1.8mm.

[0047] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. 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 two-core DC cable, characterized in that: The cable core (1) comprises a cable core (1), a filling strip (2), a buffer layer (3), an inner cushion layer (4), an anti-seismic layer (5), an armor layer (6) and an outer sheath (7); the cable core (1) comprises two parallel cable core monomers (11) of equal radius; the outer layer of the cable core (1) is sequentially provided with a buffer layer (3), an inner cushion layer (4), an anti-seismic layer (5), an armor layer (6) and an outer sheath (7); and the filling strip (2) is provided between the cable core (1) and the buffer layer (3); The cable core monomer (11) comprises a conductor (111), a wrapped semiconductive layer (112) and an insulating layer (113) arranged from the inside to the outside, the outer layer of the insulating layer (113) is a tooth-shaped protrusion (11331), and the tooth-shaped protrusions (11331) of the two cable core monomers (11) are provided with a protruding surface (11332) abutting against each other at the contact point.

2. A two-core DC cable according to claim 1, characterized in that: The conductor (111) comprises a circular twisted conductor (1111) and a parallel strip conductor (1112) arranged on the outer layer of the circular twisted conductor (1111); the circular twisted conductor (1111) is obtained by twisting and pressing a plurality of copper wires or aluminum wires; the strip conductor (1112) is an arc-shaped tile structure and is arranged in close contact with the circular twisted conductor (1111).

3. A two-core DC cable according to claim 1, characterized in that: The insulating layer (113) comprises a first insulating layer (1131), a second insulating layer (1132), and a third insulating layer (1133) arranged from the inside to the outside. The insulating layer (113) is made of polyethylene, and the polyethylene crystallinity of the first insulating layer (1131), the second insulating layer (1132), and the third insulating layer (1133) decreases in sequence.

4. A two-core DC cable according to claim 1, characterized in that: The filling strip (2) is made of a vulcanized ethylene-propylene rubber strip and is in close contact with the tooth-like protrusions (11331) and the protruding table surface (11332).

5. A two-core DC cable according to claim 2, characterized in that: The compression coefficient of the circular stranded conductor (1111) is 0.86-0.92, and the thickness of the strip conductor (1112) is not less than 2 mm.

6. A two-core DC cable according to claim 3, characterized in that: The height of the protruding table surface (11332) is greater than the height of the tooth-like protrusion (11331).

7. A two-core DC cable according to claim 3, characterized in that: The first insulating layer (1131) and the second insulating layer (1132) are prepared by a double-layer co-extrusion process, the thickness of the first insulating layer (1131) is 0.8-1.2 mm, and the thickness ratio between the first insulating layer (1131) and the second insulating layer (1132) is 2:

3.

8. A two-core DC cable according to claim 3, characterized in that: The third insulating layer (1133) includes a base layer and a tooth-like protrusion (11331) and a protruding surface (11332) arranged on the outer layer of the second insulating layer (1132) and parallel to the second insulating layer (1132). The tooth-like protrusion (11331) and the protruding surface (11332) are arranged outside the base layer. The tooth-like protrusion (11331) is conical, and its root radius is smaller than the top radius.

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