Cable with excellent waterproof performance
The cable design with a water-blocking tape and shielding layers addresses water penetration issues in onshore cables, enhancing insulation protection and extending service life by preventing water treeing and maintaining insulation integrity.
Patent Information
- Application Number
- CN202322733686.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-11
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2033-10-11
AI Technical Summary
Existing onshore medium-voltage cables face challenges in preventing water penetration due to their conventional structures, leading to water treeing and reduced service life, despite process improvements and chemical modifications, as metal sheaths and specialized insulation materials are impractical for cost and structural reasons.
A cable design incorporating a water-blocking tape made of semi-conductive material, a high-density polyethylene sheath, and additional layers to absorb and prevent moisture from reaching the insulation layer, combined with conductive and insulating shielding layers to manage electric fields and protect the cable.
The design effectively prevents water from contacting the insulation, significantly prolonging the cable's service life to 30 years without replacement, reducing maintenance costs by minimizing water tree formation and maintaining insulation integrity.
Smart Images
Figure CN222167990U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of cables, in particular to a cable with excellent waterproof performance. Background Art
[0002] With the development of society, cables are basically used in all parts of the country to achieve power supply or signal enhancement. In order to improve the service life of cables, most cables are installed underground. The voltage level of underground distribution cables ranges from 6kV to 35kV, and cross-linked polyethylene is often used as insulation cable. The history of cross-linked polyethylene insulated cables is fundamentally the history of anti-water treeing. Water treeing is a process in which insulation deteriorates due to water absorption. It is a phenomenon in which water penetrates into the gaps of insulation under the action of an electric field to form a tree-like arrangement, thereby reducing insulation performance.
[0003] The current countermeasures for water tree resistance in the industry include the following:
[0004] (1) Minimize the impurities and voids in the insulation, reduce the protrusions at the insulation interface, and release the local stress of the electric field. This can be achieved through process means, such as dry cross-linking, three-layer co-extrusion, and ultra-clean process.
[0005] (2) Insulation material manufacturers use physical methods to appropriately change the chemical composition of cross-linked polyethylene to improve its water tree resistance, such as changing the polymer molecular structure, polymer structural morphology, or blending different polymer materials, or using chemical methods to add additives that have an affinity with the molecular bonds of the matrix material to the polymer material to improve the interaction between the polymer and water to obtain water tree resistance.
[0006] (3) By preventing water from entering the cable, the source of water trees can be fundamentally cut off. This is often used in submarine cables to increase the waterproof layer. For example, metal sheaths such as lead sheaths can effectively prevent moisture from penetrating into the insulation and improve the reliability of the cable.
[0007] However, in the onshore cable structure, due to cost, outer diameter or weight reasons, it is almost impossible to use metal sheaths or water-tree-resistant insulation materials for underground power distribution medium-voltage cables. Instead, too much emphasis is placed on process means, but the structure continues to use ordinary methods. In most cases, such cables are either laid in pipelines or directly buried in the soil, and the cables will be subjected to long-term effects of surrounding moisture. Since the cables all use conventional structures, namely conductors, insulation, some fillers, some inner lining layers, some armor layers, and outer sheaths, although process means can delay the formation of water trees, such structures cannot effectively prevent the penetration of water ions. As time goes by, moisture will slowly penetrate into the cable insulation, causing water trees, deteriorating the insulation, and shortening the service life of the cable.
[0008] In view of this, the present utility model is proposed. Utility Model Content
[0009] The utility model aims to provide a cable with excellent waterproof performance. By arranging a water-blocking tape, the water that penetrates is absorbed, so as to ensure that the insulation layer of the cable is basically not exposed to moisture, avoid the occurrence of water tree phenomenon, and increase the service life of the cable.
[0010] In order to achieve the above purpose, the utility model adopts the following technical solutions:
[0011] The utility model provides a cable with excellent waterproof performance, which comprises at least one conductor, and an insulating layer and a water blocking tape are arranged on the outer circumference of each conductor, and the insulating layer and the water blocking tape extend in the same direction as the conductor;
[0012] The insulating layer is made of cross-linked polyethylene material;
[0013] The water-blocking tape is a semi-conductive water-blocking tape, made of the semi-conductive material, and used for absorbing moisture;
[0014] A first sheath is arranged on the outer circumferential surface of the water blocking tape, and the first sheath is made of high-density polyethylene and is used to prevent water penetration.
[0015] Preferably, the water-blocking tape comprises a first water-blocking tape and a second water-blocking tape, a copper tape shielding layer is arranged between the first water-blocking tape and the second water-blocking tape, and the copper tape shielding layer is made of copper tape.
[0016] Preferably, a conductor shielding layer is provided between the insulating layer and the conductor, and the conductor shielding layer is made of a semiconducting material. The semiconducting material is made of a cross-linked polyolefin material as a base material and carbon black is added to homogenize the electric field.
[0017] Preferably, an insulating shielding layer is provided between the insulating layer and the first water-blocking tape, and the insulating shielding layer is made of a semiconductive material. The semiconductive material is made of a peroxide-crosslinked polyolefin material as a base material and carbon black is added to homogenize the electric field.
[0018] Preferably, a filling layer is provided between the conductors, and the conductors are wrapped between the filling layers. The filling layer is composed of one or more materials selected from the group consisting of polyester tape, tin foil tape, textile fiber yarn, glass fiber yarn, cotton thread, and hemp rope to improve performance.
[0019] Preferably, an isolation sleeve is provided on the outer circumferential surface of the filling layer, and the isolation sleeve is made of high-density polyethylene to reduce moisture penetration.
[0020] Preferably, an armor layer is provided on the outer circumferential surface of the isolation sleeve, and the armor layer is a steel belt armor layer, which is used to reduce the external stress on the isolation sleeve.
[0021] Preferably, a second sheath is provided on the outer circumferential surface of the armor layer, and the second sheath is made of polyvinyl chloride to prevent cracking.
[0022] Compared with the prior art, the utility model has at least the following advantages:
[0023] (1) The utility model reduces water penetration by arranging the first water-blocking tape, the second water-blocking tape and the first sheath inside the cable, substantially absorbs the water that penetrates into the cable, prevents the insulation layer from contacting the water to form water trees, and greatly prolongs the service life of the cable. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] By reading the detailed description of the preferred embodiment below, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment and are not considered to be limiting of the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:
[0025] Figure 1 A cross-sectional view of a cable provided in an embodiment of the utility model.
[0026] in,
[0027] 1- conductor; 2- conductor shielding layer; 3- insulation layer; 4- insulation shielding layer; 5- first water blocking tape; 6- copper tape shielding layer; 7- second water blocking tape; 8- first sheath; 9- filling layer; 10- isolation sleeve; 11- armor layer; 12- second sheath. DETAILED DESCRIPTION
[0028] The technical solution of the utility model will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the utility model, rather than all of the embodiments, and are only used to illustrate the utility model, and should not be considered as limiting the scope of the utility model. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the utility model. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.
[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are 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 orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be fixed connection, detachable connection, or integrated connection; it can be mechanical connection or electrical connection; it can be directly connected or indirectly connected through an intermediate medium, or it can be internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0031] In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below.
[0032] Example
[0033] like Figure 1 As shown, this embodiment provides a cable with excellent waterproof performance. The cable absorbs the penetrated moisture by arranging at least one layer of water-blocking tape on the outer circumferential surface of the insulating layer 3, preventing the moisture from contacting the insulating layer 3 to generate water trees, thereby improving the service life of the cable.
[0034] In this example, the cable includes at least one conductor 1, which is the most basic and indispensable main component for the product to perform the current or electromagnetic wave information transmission function, and can also be called a conductive core. It can be made of non-ferrous metals with excellent conductive properties such as copper, aluminum, copper-clad steel, copper-clad aluminum, etc., and can also be made of optical fibers, bare copper wires, tinned wires and other materials.
[0035] An insulating layer 3 is arranged on the outer circumferential surface of each conductor 1, and the insulating layer 3 is made of cross-linked polyethylene. A conductor shielding layer 2 is also arranged between the insulating layer 3 and the conductor 1. The material of the conductor shielding layer 2 is selected to be a semiconductor material, specifically a peroxide cross-linked polyolefin material as the base material, with carbon black added. The conductor shielding layer 2 can make the electric field on the surface of the conductor 1 uniform, and prevent the formation of a gap between the conductor 1 and the insulating layer 3 to cause local discharge.
[0036] The above-mentioned water-blocking tape is installed on the outer circumferential surface of the insulating layer 3. The water-blocking tape is at least one layer and is made of a semi-conductive material. The semi-conductive material is prepared by non-woven fabric, conductive carbon black and expansion powder. The expansion powder is a highly water-absorbent polypropylene salt resin material.
[0037] In this embodiment, the water-blocking tape is set to two layers, which are a first water-blocking tape 5 and a second water-blocking tape 7. An insulating shielding layer 4 is arranged between the first water-blocking tape 5 and the insulating layer 3. The insulating shielding layer 4 is made of a semiconducting material. The semiconducting material is based on a peroxide-crosslinked polyolefin material and is made of carbon black to homogenize the electric field.
[0038] A copper tape shielding layer 6 is arranged between the first water-blocking tape 5 and the second water-blocking tape 7. The copper tape shielding layer 6 is made of copper tape. The copper tape shielding layer 6 can limit the electric field inside the cable, which not only protects the key structure of personal safety, but also serves as a grounding shielding layer to protect the cable from external electrical interference. It can also play a waterproof sealing function and also has a mechanical protection function.
[0039] A first sheath 8 is provided on the outer circumferential surface of the second water-blocking tape 7. The first sheath 8 is made of high-density polyethylene. Although it has poor environmental stress resistance, it has a low moisture permeability and can reduce water penetration.
[0040] A filling layer 9 is arranged on the outer circumferential surface of the first sheath 8, and a plurality of the conductors 1 are arranged in the filling layer 9. The conductors 1 are evenly arranged in the filling layer 9. The filling layer 9 is made of one or a combination of materials such as polyester tape, tin foil tape, textile fiber yarn, glass fiber yarn, cotton thread, hemp rope, etc. The filling layer 9 can reduce the mechanical damage and chemical corrosion of the conductor 1 and the insulating layer 3 from the outside, and can also play a buffering role, reduce the vibration and impact of the conductor 1 and the insulating layer 3, and improve the service life of the conductor 1 and the insulating layer 3.
[0041] An isolation sleeve 10 is arranged on the outer circumferential surface of the filling layer 9. The isolation sleeve 10 is also made of high-density polyethylene to reduce water penetration.
[0042] An armor layer 11 is arranged on the outer circumferential surface of the isolation sleeve 10. The armor layer 11 is selected to be a steel belt armor layer 11. The armor layer 11 can reduce the external stress on each internal component and increase the service life of the cable.
[0043] A second sheath 12 is provided on the outer circumferential surface of the armor layer 11. The second sheath 12 is made of polyvinyl chloride, which has strong resistance to environmental stress and excellent crack resistance. It can ensure that the cable will not crack randomly during use, causing internal components to contact the outside world and reduce its service life.
[0044] In order to further deepen the understanding of the present invention, the following specific implementation methods are given:
[0045] After the cable is buried underground, under the invasion of surrounding moisture, the second sheath 12 has a large moisture permeability. After a period of time, a small amount of moisture will penetrate into the interior of the cable and pass through the armor layer 11. The moisture permeability of the high-density polyethylene material used in the isolation sleeve 10 is relatively small. In addition, with the protection of the armor layer 11, the external stress it is subjected to is small, it is insensitive to changes in ambient temperature, and it is not easy to crack. It can not only minimize the infiltrated moisture, but also have a longer service life. Then the moisture that has not been blocked passes through the isolation sleeve 10 and is partially blocked again by the first sheath 8. Then the remaining moisture will be completely absorbed by the first water-blocking tape 5 and the second water-blocking tape 7 when passing through the first water-blocking tape 5 and the second water-blocking tape 7. In this way, it can be ensured that almost no moisture can pass through the second water-blocking tape 7 to reach the insulating layer 3, thereby avoiding the formation of water trees and improving the service life of the cable.
[0046] The utility model almost completely absorbs the infiltrated water by setting the first sheath 8, the first water blocking tape 5 and the second water blocking tape 7, ensuring that the insulating layer 3 is basically not in contact with the water, and there is no water tree, thereby improving the service life of the cable. Although compared with the cable of ordinary structure, the utility model increases the cost of the first water blocking tape 5, the second water blocking tape 7 and the first sheath 8, compared with the ordinary structure underground cable that needs to be replaced every 8-10 years, the cable provided by the utility model does not need to be replaced due to the effect of groundwater for 30 years, which can greatly reduce the replacement cost overall.
[0047] Finally, it is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the principles and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.
Claims
1. A cable with excellent waterproof performance, characterized in that: It comprises at least one conductor, and an insulating layer and a water blocking tape are arranged on the outer circumference of each conductor, and the insulating layer and the water blocking tape extend in the same direction as the conductor; The insulating layer is made of cross-linked polyethylene material; The water-blocking tape is a semi-conductive water-blocking tape, made of the semi-conductive material, and used for absorbing moisture; A first sheath is provided on the outer circumferential surface of the water blocking tape, and the first sheath is made of high-density polyethylene and is used to prevent water penetration; The water blocking tape comprises a first water blocking tape and a second water blocking tape, a copper tape shielding layer is arranged between the first water blocking tape and the second water blocking tape, and the copper tape shielding layer is made of copper tape; A conductor shielding layer is provided between the insulating layer and the conductor, and the conductor shielding layer is made of a semiconducting material, and the semiconducting material is made of a peroxide cross-linked polyolefin material as a base material and carbon black is added to homogenize the electric field; An insulating shielding layer is arranged between the insulating layer and the first water-blocking tape. The insulating shielding layer is made of a semiconductive material. The semiconductive material is made of a peroxide cross-linked polyolefin material as a base material and carbon black is added to homogenize the electric field.
2. The cable according to claim 1, characterized in that A filling layer is arranged between the conductors, and the conductor is wrapped between the filling layers.
3. The cable according to claim 2, characterized in that The outer circumferential surface of the filling layer is provided with an isolation sleeve, which is made of high-density polyethylene and is used to reduce moisture penetration.
4. The cable according to claim 3, characterized in that An armor layer is arranged on the outer circumferential surface of the isolation sleeve, and the armor layer is a steel belt armor layer, which is used to reduce the external stress on the isolation sleeve.
5. The cable according to claim 4, characterized in that A second sheath is arranged on the outer circumferential surface of the armor layer, and the second sheath is made of polyvinyl chloride material to prevent cracking.