Medium-voltage overhead cable

Abstract

The utility model belongs to the technical field of aerial cables, and discloses a medium-voltage aerial cable, which comprises a conductor, a semi-conductive waterproof layer, a semi-conductive shielding layer, an insulating layer and an outer coating layer. The periphery of the conductor is coated with the semi-conductive waterproof layer, the periphery of the semi-conductive waterproof layer is coated with the semi-conductive shielding layer, the periphery of the semi-conductive shielding layer is coated with the insulating layer, and the periphery of the insulating layer is coated with the outer coating layer. The semi-conductive water-blocking layer in the medium-voltage aerial cable can play a longitudinal water-blocking role on water vapor in the environment, prevent the water vapor from gathering towards the middle area of the medium-voltage aerial cable, avoid serious bending of the middle area of the medium-voltage aerial cable, and reduce the risk of breakage of the medium-voltage aerial cable in the use process. The semi-conductive water-blocking layer has a semi-conductive characteristic, and even if certain water vapor is absorbed, the electric field balance of the medium-voltage aerial cable can be ensured, so that the voltage values at all positions of the conductor are equal, the potential difference on the conductor is avoided, and the use safety of the medium-voltage aerial cable is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to overhead cable technical field especially relates to a medium voltage overhead cable. BACKGROUND

[0002] Overhead cable is a kind of transmission cable between overhead conductor and underground cable, with the development of urbanization construction of our country, the demand of long-distance overhead cable is increasing. Overhead cable is exposed to the outside environment for a long time, especially in the rainforest area with more rain, a large amount of water vapor is easy to enter the inside of overhead cable, the entry of water vapor not only easily causes the unevenness of overhead cable electric field, the voltage value of each place on conductor is not equal, there is potential difference, even can cause overhead cable short circuit, influence the use safety of overhead cable. And water vapor will gather to the middle region of overhead cable under the action of gravity, cause the middle region of overhead cable to bend seriously, improve the risk of breaking of overhead cable in use.

[0003] Therefore, a medium voltage overhead cable is needed to solve the above technical problems. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a kind of medium voltage overhead cable, can solve the voltage of each place on conductor not equal after entering water vapor in overhead cable, there is potential difference, even cause overhead cable short circuit, while water vapor will gather to the middle region of overhead cable under the action of gravity, cause the middle region of overhead cable to bend seriously, improve the risk of breaking of overhead cable in use problem.

[0005] To achieve this purpose, the utility model adopts the following technical solutions:

[0006] A kind of medium voltage overhead cable, comprising:

[0007] Conductor;

[0008] Semiconductive water barrier layer, the semiconductive water barrier layer is covered in the outer periphery of the conductor;

[0009] Semiconductive shielding layer, the semiconductive shielding layer is covered in the outer periphery of the semiconductive water barrier layer;

[0010] Insulating layer, the insulating layer is covered in the outer periphery of the semiconductive shielding layer;

[0011] Outer sheath layer, the outer sheath layer is covered in the outer periphery of the insulating layer.

[0012] As the preferred technical scheme of medium voltage overhead cable, the semiconductive water barrier layer includes two semiconductive water barrier tapes, two semiconductive water barrier tapes are reversely overlapped and wrapped around the outer periphery of the conductor.

[0013] As the preferred technical scheme of the medium voltage overhead cable, the semi-conductive water-blocking layer further comprises semi-conductive water-blocking yarns filled in the gaps between the semi-conductive water-blocking tapes and the conductor.

[0014] As the preferred technical scheme of the medium voltage overhead cable, the material of the semi-conductive shielding layer is semi-conductive cross-linked polyethylene shielding material or semi-conductive thermoplastic polypropylene shielding material, and the thickness of the semi-conductive shielding layer is 0.38mm-1.02mm.

[0015] As the preferred technical scheme of the medium voltage overhead cable, the semi-conductive shielding layer and the insulation layer are integrally formed by double-layer co-extrusion.

[0016] Alternatively, the semi-conductive shielding layer, the insulation layer and the outer sheath layer are integrally formed by three-layer co-extrusion.

[0017] As the preferred technical scheme of the medium voltage overhead cable, the conductor is one of full aluminum conductor, steel-cored aluminum alloy conductor or full aluminum alloy conductor.

[0018] As the preferred technical scheme of the medium voltage overhead cable, the conductor is formed by twisting a plurality of wires, and when the steel-cored aluminum alloy conductor is selected as the conductor, the nominal diameter of the finished compact steel-cored aluminum alloy wire is 1%-3% smaller than that of the non-compact steel-cored aluminum alloy wire.

[0019] As the preferred technical scheme of the medium voltage overhead cable, the medium voltage overhead cable further comprises at least one reinforcing wire, the reinforcing wire is arranged inside the outer sheath layer, and the reinforcing wire extends along the length direction of the outer sheath layer.

[0020] As the preferred technical scheme of the medium voltage overhead cable, the outer sheath layer is made of a mixed material of high-density polyethylene and carbon black additive, and the thickness of the outer sheath layer is 1.63mm-5.81mm.

[0021] As the preferred technical scheme of the medium voltage overhead cable, the material of the insulation layer is cross-linked polyethylene insulation material, water tree-resistant cross-linked polyethylene insulation material or thermoplastic polypropylene insulation material, and the thickness of the insulation layer is 1.72mm-8.39mm.

[0022] The utility model discloses the beneficial effect is:

[0023] The medium-voltage overhead cable has the semi-conductive water-resisting layer, which can play a role in vertically resisting water in the environment, prevent water vapor from gathering in the middle region of the medium-voltage overhead cable, avoid the middle region of the medium-voltage overhead cable from being seriously bent, and reduce the risk of the medium-voltage overhead cable from being broken in the use process. Meanwhile, the semi-conductive water-resisting layer has the semi-conductive property, so that even if the semi-conductive water-resisting layer absorbs certain water vapor, the electric field of the medium-voltage overhead cable can be balanced, the voltage values of the conductor at all places are equal, the potential difference on the conductor is avoided, and the use safety of the medium-voltage overhead cable is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural schematic view of the medium-voltage overhead cable.

[0025] In the drawings:

[0026] 1, conductor; 2, semi-conductive water-resisting layer; 21, semi-conductive water-resisting tape; 22, semi-conductive water-resisting yarn; 3, semi-conductive shielding layer; 4, insulation layer; 5, outer covering layer. DETAILED DESCRIPTION

[0027] The utility model makes further detailed explanation in combination with the drawings and examples. It can be understood that the specific examples described here are only used to explain the utility model, and not limit the utility model. In addition, it needs to be explained that in order to facilitate the description, only the part related to the utility model is shown in the drawings, not all structures.

[0028] In the description of the utility model, unless another explicit provision and limitation, the terms "connected", "connected", "fixed" should be broad sense understanding, for example, can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through the intermediate medium, can be the communication of two elements or the interaction of two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0029] In the utility model, unless another explicit provision and limitation, the first feature is "on" or "under" the second feature, which can include the direct contact of the first and second features, or the contact of the first and second features through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes the first feature directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "below" the second feature includes the first feature directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0030] In the description of the present embodiment, the terms "upper", "lower", "right", "left", and the like, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used to distinguish in the description, and have no special meaning.

[0031] As shown in Figure 1 The present embodiment provides a medium-voltage overhead cable, which comprises a conductor 1, a semi-conductive water-blocking layer 2, a semi-conductive shielding layer 3, an insulating layer 4, and an outer sheath layer 5. The semi-conductive water-blocking layer 2 is wrapped around the outer periphery of the conductor 1, the semi-conductive shielding layer 3 is wrapped around the outer periphery of the semi-conductive water-blocking layer 2, the insulating layer 4 is wrapped around the outer periphery of the semi-conductive shielding layer 3, and the outer sheath layer 5 is wrapped around the outer periphery of the insulating layer 4.

[0032] By wrapping the semi-conductive water-blocking layer 2 around the outer periphery of the conductor 1, the semi-conductive water-blocking layer 2 can play a role in vertically blocking water vapor in the environment, preventing water vapor from accumulating in the middle region of the medium-voltage overhead cable, avoiding serious bending in the middle region of the medium-voltage overhead cable, and reducing the risk of breaking of the medium-voltage overhead cable during use. At the same time, the semi-conductive water-blocking layer 2 has semi-conductive properties, so that even if the semi-conductive water-blocking layer 2 can absorb a certain amount of water vapor, it can also ensure the balance of the electric field of the medium-voltage overhead cable, thereby making the voltage values at different parts of the conductor 1 equal, avoiding the existence of potential difference on the conductor 1, and ensuring the safe use of the medium-voltage overhead cable. Wrapping the semi-conductive shielding layer 3 around the outer periphery of the semi-conductive water-blocking layer 2 not only further improves the balance of the electric field of the medium-voltage overhead cable, but also shields external electromagnetic interference, thereby further improving the stability of current and voltage transmission of the medium-voltage overhead cable. The setting of the outer sheath layer 5 can make the medium-voltage overhead cable have the properties of resistance to extrusion, friction and aging, thereby ensuring the service life of the medium-voltage overhead cable.

[0033] In the embodiment, the semi-conductive water-resisting layer 2 comprises two semi-conductive water-resisting tapes 21, which are reversely and layer by layer wrapped around the outer periphery of the conductor 1. That is, one semi-conductive water-resisting tape 21 is spirally wound from bottom to top along the conductor 1, and the second semi-conductive water-resisting tape 21 is spirally wound from top to bottom along the conductor 1. In the process of winding, the second semi-conductive water-resisting tape 21 will wrap the gap in the process of winding the first semi-conductive water-resisting tape 21, so as to ensure that the semi-conductive water-resisting layer 2 is tightly wrapped around the outer periphery of the conductor 1, and further ensure that the voltage at each position of the conductor 1 is equal, and the electric field of the medium-voltage overhead cable is balanced. Further, the semi-conductive water-resisting layer 2 further comprises semi-conductive water-resisting yarns 22, which are filled in the gap between the semi-conductive water-resisting tapes 21 and the conductor 1, thereby further improving the roundness of the medium-voltage overhead cable and further improving the water-resisting effect thereof.

[0034] In the embodiment, the material of the semi-conductive shielding layer 3 is semi-conductive cross-linked polyethylene shielding material or semi-conductive thermoplastic polypropylene shielding material, so as to ensure that the semi-conductive shielding layer 3 is tightly wrapped around the outer periphery of the semi-conductive water-resisting layer 2, and there is no gap between the two. In this way, the problem of air gap discharge between the semi-conductive shielding layer 3 and the semi-conductive water-resisting layer 2 can be avoided, and the safety of the medium-voltage overhead cable in use can be improved. The selection of the material of the semi-conductive shielding layer 3 is not limited herein. Preferably, the thickness of the semi-conductive shielding layer 3 is controlled to be 0.38mm-1.02mm, so as to ensure the shielding effect of the medium-voltage overhead cable while avoiding excessive weight and reducing the risk of breakage of the medium-voltage overhead cable in use. The thickness of the semi-conductive shielding layer 3 can be selected according to the design requirements of the medium-voltage overhead cable, and is not specifically limited herein.

[0035] In an embodiment, the semi-conductive shielding layer 3 and the insulation layer 4 are integrally formed by double-layer co-extrusion, so as to tightly adhere the semi-conductive shielding layer 3 and the insulation layer 4, prevent gaps therebetween, and further prevent air gap discharge therebetween, so as to ensure the safety and insulation of the medium-voltage overhead cable. Air gap discharge is a branch of gas discharge. Dry gas is usually a good insulator, but when there are free charged particles in the gas, it becomes a charged conductor. At this time, if two electrodes are placed in the gas and a voltage is applied, a current will flow through the gas, which is called gas discharge. The gas discharge is not described in detail herein.

[0036] In another embodiment, the semi-conductive shielding layer 3, the insulation layer 4 and the outer sheath layer 5 are integrally formed by three-layer co-extrusion. In this way, not only the semi-conductive shielding layer 3 and the insulation layer 4 are tightly adhered to avoid air gap discharge therebetween, but also the medium-voltage overhead cable is more compact. It is worth noting that both the double-layer co-extrusion process and the three-layer co-extrusion process are common processing techniques in the field of cable manufacturing, and do not belong to the key protection content of the present application.

[0037] In this embodiment, the conductor 1 is one of an all-aluminum conductor, a steel-cored aluminum alloy conductor, or an all-aluminum alloy conductor. Compared with a conductor 1 made of copper material, the conductor 1 made of aluminum material, steel-cored aluminum alloy material, or all-aluminum alloy material is more lightweight, and further reduces the risk of fracture of the medium-voltage overhead cable. Further, the conductor 1 is formed by twisting a plurality of wires. When the conductor 1 is selected to be a steel-cored aluminum alloy conductor, the nominal diameter of the finished compact steel-cored aluminum alloy wire is 1% to 3% smaller than the nominal diameter of the non-compact steel-cored aluminum alloy wire. That is, the nominal diameter of the twisted steel-cored aluminum alloy wire is 1% to 3% smaller than the nominal diameter of the untwisted steel-cored aluminum alloy wire. In this way, the twisting density of the steel-cored aluminum alloy wire in the steel-cored aluminum alloy conductor 1 can be calculated. The twisting density of the wire affects the tensile strength of the conductor 1. The better the tensile strength of the conductor 1, the smaller the risk of fracture of the medium-voltage overhead cable. Controlling the nominal diameter of the twisted steel-cored aluminum alloy wire to be 1% to 3% smaller than the nominal diameter of the untwisted steel-cored aluminum alloy wire can enable the conductor 1 to stably transmit voltage and current while having good tensile strength, thereby reducing the risk of fracture of the medium-voltage overhead cable and further improving the safety of use.

[0038] As preferred, the medium-voltage overhead cable further comprises at least one reinforcing wire, wherein the reinforcing wire is arranged inside the outer sheath 5 and extends along the length direction of the outer sheath 5. By arranging the reinforcing wire inside the outer sheath 5, the tensile strength of the medium-voltage overhead cable can be further improved, the degree of bending after being overhead can be reduced, and the risk of fracture of the medium-voltage overhead cable can be further reduced.

[0039] In this embodiment, the outer sheath 5 is made of a mixed material of high-density polyethylene and carbon black additives. The high-density polyethylene has high hardness, high tensile strength, good wear resistance, and good chemical stability, so that the outer sheath 5 has good hardness, tensile resistance, wear resistance, and aging resistance. The addition of carbon black additives can improve the ability of the outer sheath 5 to resist ultraviolet radiation, and further improve the service life of the medium-voltage overhead cable. Further, the thickness of the outer sheath 5 is 1.63 mm to 5.81 mm. The thickness of the outer sheath 5 can be selected according to the use environment and design requirements of the medium-voltage overhead cable, which is not specifically limited herein.

[0040] In this embodiment, the material of the insulation layer 4 is cross-linked polyethylene insulation material, water tree-resistant cross-linked polyethylene insulation material, or thermoplastic polypropylene insulation material. The selection of the material of the insulation layer 4 can be selected according to the design requirements, which is not specifically limited herein. The thickness of the insulation layer 4 is 1.72 mm to 8.39 mm, which is specifically selected according to the specification of the medium-voltage overhead cable, which is not specifically limited herein.

[0041] Obviously, the above embodiments of the present application are merely examples for clearly illustrating the present application, and are not intended to limit the implementation modes of the present application. For those skilled in the art, various obvious changes, re-adjustments and replacements can be made without departing from the protection scope of the present application. Here, it is not necessary and also impossible to enumerate all the implementation modes. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application claim.

Claims

1. A medium voltage overhead electrical cable, characterized in that, It comprises: a conductor (1); a semi-conductive water-blocking layer (2) covering the outer periphery of the conductor (1); a semi-conductive shielding layer (3) covering the outer periphery of the semi-conductive water-blocking layer (2); an insulation layer (4) covering the outer periphery of the semi-conductive shielding layer (3); an outer sheath layer (5) covering the outer periphery of the insulation layer (4).

2. Medium voltage overhead cable according to claim 1, characterized in that The semi-conductive water-blocking layer (2) comprises two semi-conductive water-blocking tapes (21) which are reversely overlapped and wrapped around the outer periphery of the conductor (1).

3. Medium voltage overhead cable according to claim 2, characterized in that The semi-conductive water-blocking layer (2) further comprises semi-conductive water-blocking yarns (22) which are filled in the gaps between the semi-conductive water-blocking tapes (21) and the conductor (1).

4. Medium voltage overhead cable according to claim 1, characterized in that The semi-conductive shielding layer (3) is made of semi-conductive cross-linked polyethylene shielding material or semi-conductive thermoplastic polypropylene shielding material, and has a thickness of 0.38-1.02 mm.

5. Medium voltage overhead cable according to claim 4, characterized in that The semi-conductive shielding layer (3) and the insulation layer (4) are integrally formed by double-layer co-extrusion. Alternatively, the semi-conductive shielding layer (3), the insulation layer (4) and the outer sheath layer (5) are integrally formed by three-layer co-extrusion.

6. Medium voltage overhead cable according to claim 1, characterized in that The conductor (1) is one of full aluminum conductor, steel-cored aluminum alloy conductor or full aluminum alloy conductor.

7. Medium voltage overhead cable according to claim 6, characterized in that The conductor (1) is formed by twisting a plurality of wires, and when the steel-cored aluminum alloy conductor is selected, the nominal diameter of the finished compact steel-cored aluminum alloy conductor wire is 1-3% smaller than that of the non-compact steel-cored aluminum alloy conductor wire.

8. Medium voltage overhead cable according to any of claims 1-7, characterized in that, The medium-voltage overhead cable further comprises at least one reinforcing wire which is arranged inside the outer sheath layer (5) and extends along the length direction of the outer sheath layer (5).

9. Medium voltage overhead cable according to any of claims 1-7, characterized in that, The outer sheath layer (5) is made of a mixture of high-density polyethylene material and carbon black additives, and has a thickness of 1.63-5.81 mm.

10. Medium voltage overhead cable according to any of claims 1-7, characterized in that, The insulation layer (4) is made of cross-linked polyethylene insulation material, water tree-resistant cross-linked polyethylene insulation material or thermoplastic polypropylene insulation material, and has a thickness of 1.72-8.39 mm.

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