Cable semi-conductive buffer layer and cable

Abstract

The utility model relates to the field of cable manufacturing, in particular to a cable semi-conductive buffer layer and a cable, and the cable semi-conductive buffer layer comprises a first semi-conductive buffer water-blocking tape, a semi-conductive buffer tape and a second semi-conductive buffer water-blocking tape which are overlapped, covered and wrapped from inside to outside. According to the utility model, the three layers of buffer strips adopted by the semi-conductive buffer layer are not all semi-conductive buffer water-blocking tapes, but the middle layer is a semi-conductive buffer tape, and tests verify that the whole structure of the formed buffer layer semi-conductive buffer layer can also meet the water-blocking effect of the high-voltage cable, so that the service life of the high-voltage cable is prolonged. Compared with a structure in which three layers of overlapped layers are completely water-blocking tapes, the cost can be reduced; meanwhile, a negative gap close contact structure is arranged between the semi-conductive buffer layer and the corrugated aluminum sleeve, and the gap is reasonably arranged, so that the problem of compression after insulation thermal expansion caused by an overlarge gap is solved, or the problems of poor electrical contact or weakened water blocking effect caused by an oversmall gap is solved.

Description

Technical Field

[0001] The utility model relates to the field of cable manufacturing, in particular to a semi-conductive buffer layer of a cable and a cable. Background Art

[0002] At present, the high-voltage power cables operating in China are mainly of the corrugated aluminum sheath structure, accounting for more than 90%. The production and manufacturing processes of the cables and their supporting accessories are mature, and the application and operation experience are rich. However, in recent years, the frequent ablation failures of the buffer layers of high-voltage cables have attracted wide attention in the industry. Research shows that the main reasons for the ablation of the buffer layer are as follows: there is uneven line contact between the buffer layer and the corrugated aluminum sheath, the fit is too loose, resulting in floating discharge and ablation; the volume resistivity and surface resistance of the semi-conductive buffer strip itself are too large; the semi-conductive buffer water-blocking strip absorbs moisture, etc.

[0003] The existing national standards for high-voltage cable products, GB / T 11017 and GB / T 18890, do not clearly stipulate the structure and thickness of the semi-conductive buffer water-blocking layer, resulting in differences among various cable enterprises in the design of the thickness of the buffer water-blocking layer, the winding process, and the gap control process between the buffer water-blocking layer and the corrugated aluminum sheath. The electrical performance and water-blocking performance indicators of the buffer water-blocking layer are inconsistent, and there is a lack of unified standards.

[0004] In order to reduce costs, some cable enterprises design the overall thickness of the buffer water-blocking layer to be relatively thin, and the gap control between the buffer water-blocking layer and the corrugated aluminum sheath is insufficient, and the electrical and water-blocking performance of the cable cannot meet the requirements of long-term safe and reliable operation. For example, two layers of semi-conductive buffer water-blocking strips are wound by overlapping or with gaps (abbreviated as "two-layer overlap" and "three-layer gap" respectively); while some enterprises have the problem of "design overrun" for the buffer water-blocking layer. For example, three layers of semi-conductive buffer water-blocking strips are wound by overlapping (abbreviated as "three-layer overlap"), resulting in an increase in the cost of cable products.

[0005] Therefore, those skilled in the art are committed to developing a semi-conductive buffer layer of a cable and a cable that can ensure the close contact between the buffer layer and the corrugated aluminum sheath, as well as the electrical performance and water-blocking performance. Summary of the Utility Model

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the utility model is to provide a semi-conductive buffer layer of a cable and a cable that can ensure the close contact between the buffer layer and the corrugated aluminum sheath, as well as the electrical performance and water-blocking performance.

[0007] To achieve the above object, the utility model provides a semi-conductive buffer layer of a cable, which includes, from the inside to the outside, a first semi-conductive buffer water-blocking strip, a semi-conductive buffer strip, and a second semi-conductive buffer water-blocking strip wound by overlapping.

[0008] Preferably, the single-layer thickness of the first semi-conductive buffer water-blocking tape, the semi-conductive buffer tape, and the second semi-conductive buffer water-blocking tape is between 1.7 mm and 2 mm.

[0009] Preferably, the first semi-conductive buffer water-blocking tape and the second semi-conductive buffer water-blocking tape are composed of a semi-conductive non-woven fabric layer, a polyacrylate water-blocking powder layer, and a semi-conductive fluffy cotton layer from the inside to the outside.

[0010] Preferably, the semi-conductive buffer tape is composed of a semi-conductive non-woven fabric and semi-conductive fluffy cotton from the inside to the outside.

[0011] The present invention also provides a cable, including the cable semi-conductive buffer layer as described above.

[0012] Preferably, from the inside to the outside, it includes an insulating wire core, the cable semi-conductive buffer layer, a corrugated aluminum sheath, and an outer sheath.

[0013] Preferably, the total depth of the valleys of the corrugated aluminum sheath rolling into the cable semi-conductive buffer layer is 3-5 mm.

[0014] The beneficial effects of the present utility model are as follows: In the semi-conductive buffer layer of the present utility model, not all of the three-layer buffer tapes are semi-conductive buffer water-blocking tapes. Instead, the middle layer is set as a semi-conductive buffer tape. Through experimental verification, the overall structure of the semi-conductive buffer layer formed thereby can also meet the water-blocking effect of high-voltage cables, and can reduce costs compared with the structure of "three-layer overlap" which is completely a water-blocking tape; at the same time, between the semi-conductive buffer layer and the corrugated aluminum sheath is a "negative" gap close contact structure, and the gap is set reasonably to prevent problems such as insulation thermal expansion and pressure after excessive gaps, or problems such as poor electrical contact or weakened water-blocking effect due to too small gaps. Description of the Drawings

[0015] Figure 1 is a schematic structural diagram of a cable in a specific embodiment of the present utility model.

[0016] Figure 2 is a schematic structural diagram of the first semi-conductive buffer water-blocking tape in a specific embodiment of the present utility model.

[0017] Figure 3 is a schematic structural diagram of the semi-conductive buffer tape in a specific embodiment of the present utility model.

[0018] Figure 4 is a schematic structural diagram of the cooperation between the cable semi-conductive buffer layer and the corrugated aluminum sheath in a specific embodiment of the present utility model. Specific Embodiment

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in the description of the present invention, the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific manner, and therefore should not be construed as a limitation to the present invention. Terms such as "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0020] The present invention provides a cable, as Figure 1 shown, which includes an insulating core 1, a cable semi-conductive buffer layer 2, a corrugated aluminum sheath 3, and an outer sheath 4 from the inside to the outside. The cable semi-conductive buffer layer includes, from the inside to the outside, a first semi-conductive buffer water-blocking tape 21, a semi-conductive buffer tape 22, and a second semi-conductive buffer water-blocking tape 23 that are overlapped and lapped around. In this embodiment, as Figure 2 shown, the first semi-conductive buffer water-blocking tape 21 and the second semi-conductive buffer water-blocking tape 23 are composed of a semi-conductive non-woven fabric layer 211, a polyacrylate water-blocking powder layer 212, and a semi-conductive fluffy cotton layer 213 from the inside to the outside. The semi-conductive fluffy cotton layer 213 contains carbon black and has three functions of semi-conductivity, buffering, and water-blocking. After testing, the volume resistivity of the first semi-conductive buffer water-blocking tape 21 in the present invention is ≤500Ω·m, the surface resistance is ≤350Ω, the moisture content is ≤7%, the pH is 7.2±0.3, and the tensile strength is ≤4.0N / mm.

[0021] As Figure 3 shown, the semi-conductive buffer tape 22 is composed of a semi-conductive non-woven fabric 221 and a semi-conductive fluffy cotton 222 from the inside to the outside, and does not have the function of water absorption and expansion. After testing, the volume resistivity of the semi-conductive buffer tape 22 in the present invention is ≤500Ω·cm, the surface resistance is ≤350Ω, and the tensile strength is ≤4.0N / mm.

[0022] In this embodiment, the single-layer thickness of the first semi-conductive buffer water-blocking tape 21, the semi-conductive buffer tape 22, and the second semi-conductive buffer water-blocking tape 23 is between 1.7mm and 2mm. After overlapping and lapping around, the cable semi-conductive buffer layer measures 14.5±0.5mm from both sides. By using the semi-conductive buffer layer of the present invention, the water-blocking effect can be improved, as well as the thermal expansion absorption ability during insulation operation. The buffer layer thickness can fill the troughs of the corrugated aluminum sheath, ensuring excellent electrical contact and avoiding the risk of floating discharge.

[0023] As Figure 4As shown in the figure, after the corrugated aluminum sheath 3 is processed in the present invention, the depth h of the trough of the corrugated aluminum sheath 3 rolling into the cable semiconductive buffer layer 2 is 3-5 mm, that is, a "negative" gap is designed between the semiconductive buffer layer 2 and the corrugated aluminum sheath 3, and the gap is set to 3-5 mm. That is, there is close contact between the corrugated aluminum sheath and the semiconductive buffer layer, and the troughs of the corrugations of the aluminum sheath are tightly rolled into the semiconductive buffer layer, realizing the transition from uneven "line contact" to uniform "surface contact". Such a gap setting can prevent problems such as insulation being compressed after thermal expansion due to too large a gap, or poor electrical contact or weakened water-blocking effect due to too small a gap.

[0024] The preferred specific embodiments of the present utility model have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present utility model without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present utility model through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A semiconductive buffer layer for a cable, characterized by: From the inside to the outside, it comprises a first semi-conductive buffer water-blocking tape (21), a semi-conductive buffer tape (22) and a second semi-conductive buffer water-blocking tape (23) which are overlapped and wrapped.

2. The cable semiconductive buffer layer according to claim 1, characterized in that: The single layer thickness of the first semiconductive buffer water-blocking tape (21), the semiconductive buffer tape (22) and the second semiconductive buffer water-blocking tape (23) is between 1.7 mm and 2 mm.

3. The cable semiconductive buffer layer according to claim 1, characterized in that: The first semi-conductive buffer water-blocking tape (21) and the second semi-conductive buffer water-blocking tape (23) are composed, from the inside to the outside, of a semi-conductive non-woven fabric layer (211), a polyacrylic acid water-blocking powder layer (212), and a semi-conductive fluffy cotton layer (213).

4. The cable semiconductive buffer layer according to claim 1, characterized in that: The semi-conductive buffer belt (22) is composed of a semi-conductive non-woven fabric (221) and semi-conductive fluffy cotton (222) from the inside to the outside.

5. A cable, characterized in that: The cable comprises a semiconductive buffer layer (2) as claimed in any one of claims 1 to 4.

6. The cable according to claim 5, characterized in that: From the inside to the outside, it comprises an insulating wire core (1), the cable semi-conductive buffer layer (2), a corrugated aluminum sheath (3) and an outer sheath (4).

7. The cable according to claim 6, characterized in that: The depth h of the trough of the corrugated aluminum sleeve (3) rolling into the cable semi-conductive buffer layer (2) is 3-5 mm.

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