Buffering water-blocking tape, cable and water-blocking tape wrapping method

Abstract

The invention relates to the technical field of cables, in particular to a buffer water-blocking tape, a cable and a water-blocking tape wrapping method. The buffer water-blocking tape comprises a tape body, and a metal foil is arranged on the tape body. The buffer water-blocking tape is simple in structure, can avoid cable breakdown caused by ablation of the buffer layer when being used for a cable, improves the safety and reliability of the cable, has high water-blocking property, and also has high bending performance.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a buffer water-blocking tape, a cable and a water-blocking tape wrapping method. Background Art

[0003] With the large-scale application of high-voltage cables in my country, the accidents of insulation water tree aging and cable breakdown caused by moisture intruding into the cable from the surrounding environment are increasing year by year. More and more users are in urgent need of cables with good water-blocking performance to further improve the safety and reliability of the power system. In addition, in recent years, the phenomenon of "ablation discharge" of the buffer layer has repeatedly occurred in domestic high-voltage cable line faults.

[0004] The buffer water-blocking layer between the metal sheath of the high-voltage cable and the cable core is an important component of the cable and has an important influence on the mechanical, electrical and thermal properties of the cable. The metal aluminum sheath of the high-voltage cable can be divided into corrugated aluminum sheath and smooth aluminum sheath according to the shape of the aluminum sheath. The corrugated aluminum sheath has good bending performance, but the uneven electrical contact between the traditional corrugated aluminum sheath and the buffer layer leads to the risk of fault-free breakdown and poor longitudinal water blocking ability; the smooth aluminum sheath high-voltage cable has poor bending performance. Therefore, how to design the buffer layer structure of the high-voltage cable so that its buffer water-blocking layer has good contact with the metal sheath, good water blocking performance and good bending performance, so as to improve the water blocking performance and electrical performance of the cable and improve the operational reliability, has become a hot topic in the cable industry. At the same time, this is of great significance to ensure the quality of cable products and the safe and stable operation of the power grid.

[0005] Therefore, those skilled in the art are committed to developing a buffer water-blocking tape, a cable and a water-blocking tape wrapping method with good contact, good water-blocking performance and good flexibility. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a buffer water-blocking tape, a cable and a water-blocking tape wrapping method with good contact, good water-blocking performance and good flexibility.

[0007] To achieve the above-mentioned object, the present invention provides a buffer water-blocking tape, comprising a tape body, on which a metal foil is provided.

[0008] Preferably, the metal foil is trapezoidal.

[0009] Preferably, the metal foil has the following dimensions:

[0010] The width of the upper base is: a=π·D+m

[0011] Wherein, a is the upper bottom width of the metal foil, D is the diameter of the insulating core, m is the overlap length when the buffer water-blocking tape is wrapped, 0.02≤m≤0.05;

[0012] The height of the metal foil is: h = (n-1)λ + n·e + p + q

[0013] Wherein, h is the height of the metal foil, n is the number of layers of the cable water-blocking tape, λ is the width of the buffer water-blocking tape, e is the thickness of the buffer water-blocking tape, p is the bonding length between the metal foil and the non-woven fabric, and q is the excess length of the metal foil leaking out of the water-blocking core along the longitudinal direction of the cable after the buffer group water tape is wrapped; 0.02≤p≤0.05, 0.02≤q≤0.05;

[0014] The width of the lower base is: b = a + h;

[0015] Wherein, b is the bottom width of the metal foil.

[0016] Preferably, the metal foil is a right-angled trapezoid, and the two bottom angles of the side connected to the strip body are 90° and 45° respectively.

[0017] Preferably, there are multiple metal foils, which are arranged at intervals.

[0018] Preferably, the spacing between the metal foils before wrapping is obtained by the following formula:

[0019]

[0020] l is the distance between adjacent metal foils before wrapping, L is the distance between metal foils along the length of the cable after wrapping, K is the wrapping pitch of the buffer water-blocking tape, and D is the diameter of the insulating core.

[0021] The present invention also provides a cable, comprising the buffer water-blocking tape as described above, wherein the metal foil is arranged on the inner side.

[0022] Preferably, the buffer water-blocking tape is the innermost water-blocking tape of the water-blocking layer, and the metal foil is in contact with the metal sheath layer.

[0023] Preferably, the portion of the metal foil extending out of the buffer water-blocking tape is sequentially wrapped around the outside of each layer of water-blocking tape and then contacts the metal sheath layer.

[0024] The present invention also provides a water-blocking tape wrapping method, comprising the following steps:

[0025] 1) placing the buffer water-blocking tape in the innermost layer, wrapping it around the outer periphery of the insulating shielding layer, and placing the metal foil on the inner side;

[0026] 2) Each layer of water-blocking tape is continuously wrapped from the inside to the outside, and the portion of the metal foil extending out of the buffer water-blocking tape is sequentially wrapped around the outside of each layer of water-blocking tape and then contacts the metal sheath layer.

[0027] The beneficial effects of the present invention are as follows: the buffer water-blocking tape of the present invention has a simple structure and can be used for cables to avoid cable breakdown caused by buffer layer ablation, thereby improving the safety and reliability of the cables, while having high water-blocking properties and high bending performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a buffer water blocking tape according to a specific embodiment of the present invention.

[0029] Figure 2 It is a schematic diagram of the metal foil structure of a specific embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of a cross-sectional structure of a cable according to a specific embodiment of the present invention.

[0031] Figure 4 It is a schematic diagram of the cross-sectional structure of the starting end of a cable according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which 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 direction, be constructed and operated in a specific manner, and therefore cannot be understood as limiting the present invention. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] like Figure 1 As shown, a buffer water-blocking tape comprises a tape body 10, on which a metal foil 1 is arranged. The buffer water-blocking tape is in the shape of a tape. In the present invention, the metal foil is arranged on the tape surface, that is, on the inner layer side when wrapping. In this embodiment, the buffer water-blocking tape is composited by a non-woven fabric infected with conductive carbon black and polyester fiber. Specifically, in this embodiment, the tape body is composed of three layers of semi-conductive non-woven fabric, polyacrylate expansion powder, and semi-conductive fluffy cotton. The polyacrylate expansion powder is coated between the non-woven fabric and the fluffy cotton to achieve a longitudinal water-blocking function, and the non-woven fabric and fluffy cotton structure achieve a buffering effect, thereby achieving a higher longitudinal water-blocking property. In this embodiment, the metal foil 1 is attached to one side of the non-woven fabric. When wrapping, the non-woven fabric side is close to the insulating wire core 6, so the metal foil is attached to the non-woven fabric side by gluing. In this embodiment, the metal foil is aluminum foil, and in other embodiments, copper foil or the like can also be used.

[0034] like Figure 1 and Figure 2 As shown, the metal foil 1 is a trapezoid. In order to achieve a better wrapping effect, the present embodiment is set to a right-angle trapezoid. The two bottom angles β and γ on the side connected / bonded to the tape body 10 are 90° and 45° respectively, so that it can maintain a stable shape with the water-blocking tape. The bottom angle is 45° so that the metal foil extending along the side of the water-blocking tape during wrapping can more easily rotate with the water-blocking tape body and wrap smoothly. Otherwise, the extended part of the metal foil is easy to swing around during the wrapping process, and wrinkles are formed when it is wrapped on the wire core.

[0035] The metal foil 1 has the following dimensions:

[0036] The width of the upper base is: a=π·D+m

[0037] Wherein, a is the width of the upper bottom of the metal foil 1, D is the diameter of the insulating core, m is the overlap length when the buffer water-blocking tape is wrapped, 0.02≤m≤0.05;

[0038] The height of the metal foil 1 is: h = (n-1)λ + n·e + p + q

[0039] Wherein, h is the height of the metal foil 1, n is the number of layers of the water-blocking tape of the water-blocking layer, λ is the width of the buffer water-blocking tape. Generally speaking, the widths of the water-blocking tapes of each layer of the water-blocking layer are consistent, that is, λ is also the width of the other layers of water-blocking tapes, e is the thickness of the buffer water-blocking tape, p is the bonding length between the metal foil 1 and the non-woven fabric, and q is the excess length of the metal foil 1 leaking out of the water-blocking core along the longitudinal direction of the cable after the buffer group water tape is wrapped; 0.02≤p≤0.05, 0.02≤q≤0.05;

[0040] The width of the lower base is: b = a + h;

[0041] Wherein, b is the bottom width of the metal foil 1.

[0042] The number of metal foils 1 is plural and they are arranged at intervals.

[0043] The spacing between the metal foils before wrapping is calculated using the following formula:

[0044]

[0045] l is the distance between adjacent metal foils before wrapping, L is the distance between metal foils along the length direction of the cable after wrapping, 0.6≤L≤1, κ is the wrapping pitch of the buffer water-blocking tape, and D is the diameter of the insulating core.

[0046] like Figure 3 and Figure 4As shown, the present invention also provides a cable, including the buffer water-blocking tape 2 as described above. The cable includes an insulating core 6, the inside of the insulating core 6 is a conductor 61, the outside of the insulating core 6 is an insulating shielding layer 62, and the outside of the insulating shielding layer 62 is a water-blocking layer 63. In this embodiment, the buffer water-blocking tape 2 is the innermost water-blocking tape of the water-blocking layer 63, that is, the water-blocking tape provided with a metal foil is set as the innermost water-blocking tape, and one side of the metal foil 1 is directly wound around the outside of the insulating shielding layer 62. In the prior art, the water-blocking layer is generally formed by wrapping 2-4 layers of water-blocking tape. The buffer water-blocking tape 2 of the present invention can be the innermost layer. In this embodiment, a total of 3 layers of water-blocking tape are wrapped. During wrapping, after the metal foil 1 extends out of the buffer water-blocking tape 2, as shown Figure 3 As shown, the metal foil is covered on the second layer of water-blocking tape. Since the length of the metal foil is long enough, after the second layer of water-blocking tape is wrapped, it can still extend until it is covered by the outermost layer of water-blocking tape. That is, the metal foil 1 is leaked outside the water-blocking core after the buffer group water tape is wrapped. The excess length q along the longitudinal direction of the cable, in this embodiment, q is set between 0.02 and 0.05m. Because there is still an excess length q, the metal foil 1 in the present invention can eventually contact the metal sheath layer 3, that is, the metal foil 1 extends out of the buffer water-blocking tape 2 and is wrapped around the outside of each layer of water-blocking tape in turn and then contacts the metal sheath layer 3. Thereby, the electrical connection between the insulating shielding layer 62 and the metal sheath layer 3 is realized, so that an electrical path is formed between the two, which can completely solve the technical problem of buffer layer ablation. At the same time, in the present invention, the metal sheath layer 3 adopts a corrugated aluminum sheath, which has good bending properties. The setting of the metal foil solves the problem of uneven electrical contact between the traditional corrugated aluminum sheath and the buffer layer. Therefore, the present invention can avoid the risk of trouble-free breakdown in the cable in the prior art.

[0047] The present invention provides a water-blocking tape wrapping method, comprising the following steps:

[0048] 1) The buffer water blocking tape 2 of the present invention is placed in the innermost layer, wrapped around the outer periphery of the insulating shielding layer 62, and the metal foil 1 is placed on the inner side;

[0049] 2) Each layer of water-blocking tape is continuously wrapped from the inside to the outside, and the metal foil 1 extending out of the buffer water-blocking tape 2 is wrapped around the outside of each layer of water-blocking tape and then contacts the metal sheath layer 3. When wrapping each layer of water-blocking tape of the present invention, an overlapping matching -4.5mm±1mm negative gap corrugation process is adopted. It has been verified that such a method can obtain a high-voltage cable with excellent longitudinal water-blocking performance.

[0050] According to the present invention, the starting position of each layer of water-blocking tape is wrapped from the inside to the outside in sequence, such as Figure 3 As shown, the starting end is stepped.

[0051] The buffer water-blocking tape of the present invention has excellent electrical connectivity and water-blocking properties, and the corrugated aluminum sheath has good bending properties, thereby solving the problem of cable ablation and breakdown and improving the reliability and safety of cable branches.

[0052] In this embodiment, 220kV 1×2500mm 2 Taking the cable specifications as an example, assuming 3 layers of water-blocking tape, the cable wrapping pitch is about 0.05m, the insulation core diameter is about 0.11m, the metal foil is aluminum foil, and the aluminum foil size (m) is calculated as follows:

[0053] The width of the upper base is: a=π·D+m

[0054] In this embodiment, m is set to 0.03m, and the upper bottom width is set in this way to ensure that the aluminum foil can wrap around the insulating core for a full circle.

[0055] The height of the aluminum foil is: h = 2λ + 3 × 0.002 + 0.03 + 0.03

[0056] In this embodiment, the width λ of each layer of water-blocking tape is consistent with 0.1m, the thickness of each layer of water-blocking tape is consistent with 0.002m, the bonding length of the aluminum foil and the non-woven fabric and the excess length outside the water-blocking core after wrapping along the longitudinal direction of the cable are both set to 0.03m.

[0057] The width of the lower base is: b=a+h.

[0058] To ensure reliable water-blocking performance, the distance between two adjacent aluminum foils wrapped around the cable is designed to be 0.8m, that is, L is 0.8m. Therefore, the distance between adjacent aluminum foils before wrapping is set to:

[0059] According to calculation, the distance between adjacent metal foils before wrapping is 5.5m.

[0060] The buffer water-blocking tape 2 prepared in this embodiment is used as the innermost water-blocking tape, which is wrapped around the outer periphery of the insulating shielding layer 62. Each layer of water-blocking tape is wrapped continuously from the inside to the outside, and then a corrugated aluminum sheath is added. The rest of the cable is prepared according to the conventional method. After preparation, a longitudinal water permeability test is performed according to the method described in GB / T 11017. In three tests, the water permeability length is within 0.5m. The conventional 220kV 1×2500mm 2 The water-permeable length of the cable is less than 1 m according to the same method. Therefore, the present invention has a higher water-blocking property.

[0061] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A buffer water blocking tape, characterized by: The invention comprises a belt body (10) on which a metal foil (1) is arranged.

2. The buffer water blocking tape according to claim 1, characterized in that: The metal foil (1) is trapezoidal.

3. The buffer water blocking tape according to claim 2, characterized in that: The metal foil (1) has the following dimensions: The width of the upper base is: a=π·D+m Wherein, a is the width of the upper bottom of the metal foil (1), D is the diameter of the insulating wire core, m is the overlap length when the buffer water-blocking tape is wrapped, and 0.02≤m≤0.05; The height of the metal foil (1) is: h = (n-1)λ + n·e + p + q Wherein, h is the height of the metal foil (1), n ​​is the number of layers of the cable water-blocking tape, λ is the width of the buffer water-blocking tape, e is the thickness of the buffer water-blocking tape, p is the bonding length between the metal foil (1) and the non-woven fabric, and q is the excess length of the metal foil (1) leaking out of the water-blocking core along the longitudinal direction of the cable after being wrapped with the buffer water-blocking tape; 0.02≤p≤0.05, 0.02≤q≤0.05; The width of the lower base is: b = a + h; Wherein, b is the bottom width of the metal foil (1).

4. The buffer water blocking tape according to claim 1, characterized in that: The metal foil (1) is a right-angled trapezoid, and the two bottom angles of the side connected to the strip body (10) are 90° and 45° respectively.

5. The buffer water blocking tape according to claim 1, characterized in that: The metal foils (1) are multiple in number and are arranged at intervals.

6. The buffer water blocking tape according to claim 5, characterized in that: The spacing between the metal foils before wrapping is calculated by the following formula: l is the distance between adjacent metal foils before wrapping, L is the distance between metal foils along the length direction of the cable after wrapping, κ is the wrapping pitch of the buffer water-blocking tape, and D is the diameter of the insulating core.

7. A cable, characterized in that: It comprises the buffer water blocking tape (2) as claimed in any one of claims 1 to 6, wherein the metal foil (1) is arranged on the inner side.

8. The cable according to claim 7, characterized in that: The buffer water-blocking tape (2) is the innermost water-blocking tape of the water-blocking layer, and the metal foil (1) is in contact with the metal sheath layer (3).

9. The cable according to claim 8, characterized in that: The portion of the metal foil (1) extending out of the buffer water-blocking tape (2) is sequentially wrapped around the outside of each layer of water-blocking tape and then contacts the metal sheath layer (3).

10. A method for wrapping a water-blocking tape, characterized in that: The following steps are involved: 1) placing the buffer water-blocking tape (2) as claimed in any one of claims 1 to 6 as the innermost layer, wrapping it around the outer periphery of the insulating shielding layer (62), and placing the metal foil (1) on the inner side; 2) Each layer of water-blocking tape is continuously wrapped from the inside to the outside, and the portion of the metal foil (1) extending out of the buffer water-blocking tape (2) is sequentially wrapped around the outside of each layer of water-blocking tape and then contacts the metal sheath layer (3).

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