Connection sealing structure and application of electrical transmission lines

Abstract

This invention discloses a connection sealing structure for electrical transmission lines, relating to the field of power engineering. The key technical points are: a structural layer made of cross-linked polyethylene on the transmission line, and a protective layer made of silicone rubber covering the outside of the structural layer. A self-made adhesive layer is provided between the structural layer and the protective layer. The adhesive layer dissolves and bonds to the inner walls of the structural layer and the protective layer, forming an integrated fused interface. The self-made adhesive layer chemically fuses the cross-linked polyethylene and silicone rubber materials into a single structure, fundamentally eliminating the existence and possibility of air gaps, thereby improving voltage withstand performance and preventing air gap discharge. Due to the presence of the adhesive layer, it has a certain repair capability, eliminating construction defects during construction and preventing moisture from penetrating the core and exterior along the compression interface, thus preventing breakdown accidents.

Description

Technical Field

[0001] This invention relates to the field of power engineering, and in particular to a connection sealing structure for electrical transmission lines and its application. Background Technology

[0002] Cross-linked polyethylene (XLPE) cables, with their reasonable structure and excellent electrical performance, have been widely used in power distribution networks and have gradually replaced traditional paper-insulated cables. However, factors such as rough cable manufacturing technology, poor construction processes, human damage, and harsh operating environments can all cause insulation defects in XLPE cables, affecting their insulation performance. Statistics from the State Grid Corporation of China show that over 95% of power cable line failures are caused by substandard installation quality by cable accessory installers.

[0003] Electrical transmission lines like cross-linked polyethylene cables are typically manufactured in 500-meter rolls. When the required cable length exceeds 500 meters, intermediate connectors are used for connection. During installation, poor stripping of the transmission lines and an unsmooth surface significantly affect the sealing of the intermediate connectors. These irregular areas, due to concentrated electric fields, can generate point discharges, leading to breakdown accidents. Summary of the Invention

[0004] One objective of this invention is to provide a connection sealing structure for an electrical transmission line, which has a perfect composite interface between the sealing product and the electrical transmission line, thereby changing the original interface characteristics. This not only significantly improves the interface's resistance to lightning strikes, but also has the advantages of being less prone to air gaps and sharp points, avoiding partial discharge, and preventing moisture from penetrating from both ends and the wire core to the compression interface.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A connection sealing structure for an electrical transmission line includes a structural layer made of cross-linked polyethylene on the electrical transmission line and a protective layer made of silicone rubber covering the outside of the structural layer. A self-made adhesive layer is provided between the structural layer and the protective layer. The adhesive layer dissolves and bonds to the inner walls of the structural layer and the protective layer, so that the structural layer and the protective layer form an integrated fused interface.

[0007] By adopting the above technical solution, a self-made adhesive layer is used. This adhesive layer chemically fuses cross-linked polyethylene material and silicone rubber material into a single structure, fundamentally eliminating the existence and possibility of air gaps, thereby improving voltage withstand performance and preventing air gap discharge. Due to the presence of the adhesive layer, it has a certain repair capability, which can eliminate construction defects generated during construction. After curing, the adhesive layer has a certain thickness, which can be used to repair knife marks and pits caused to the main insulation during construction, avoiding the generation of micro air gaps and sharp points. It can also prevent moisture from penetrating from the core and outside of the electrical transmission line along the compression interface, thus preventing breakdown accidents.

[0008] Further configuration: The structural layer has a surface treatment layer, which is a corona layer.

[0009] By employing the above technical solution, the structural layer possesses a corona layer. Various plasmas generated after air ionization, under the influence of a strong electric field, accelerate their impact on the structural layer. The energy of these plasma particles is generally between several and tens of electron volts, close to the chemical bond energy of the polyethylene material in the structural layer. Therefore, this can induce the breaking and degradation of chemical bonds in the surface molecules of the structural layer, increasing surface roughness. Simultaneously, it can remove oil, moisture, and dirt, significantly increasing the bonding strength between the adhesive layer and the structural layer when the adhesive layer is applied.

[0010] Further configuration: The structural layer has a surface treatment layer, which is a base coating layer on the structural layer. The material used for the base coating layer is the same as the material used for the self-made adhesive layer.

[0011] By adopting the above technical solution, the base coating replenishes the oxidized moisture in the sealed state, allowing the adhesive to fully cure with oxygen and enhancing the interfacial bonding force.

[0012] Further configuration: The self-made adhesive layer comprises A and B, characterized in that: A comprises the following components in parts by weight: 100 parts of base polymer, 10-25 parts of base crosslinking agent, 10-30 parts of additional crosslinking agent and 5-15 parts of filler;

[0013] The basic crosslinking agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and aminopropyltrimethoxysilane;

[0014] B comprises the following components in parts by weight: 100 parts of base polymer, 5-15 parts of filler and 0.2-0.5 parts of catalyst;

[0015] The base polymers in A and B are hydroxyl silicone oils.

[0016] By adopting the above technical solution, cross-linked polyethylene contains partially modified silane groups, and the adhesive is in contact with the cross-linked polyethylene. Under the action of a catalyst, the modified silane groups can undergo a certain cross-linking reaction with hydroxyl silicone oil, the basic cross-linking agent, and the additional cross-linking agent. The terminal hydroxyl groups of the hydroxyl silicone oil are reactive and undergo a condensation reaction with alkoxy compounds to form macromolecules through covalent bonds. Therefore, after solidification, the adhesive can be completely bonded to the cross-linked polyethylene.

[0017] The intermediate joint is made of silicone rubber. Since silicone rubber and the adhesive are largely the same type of substance, they can fuse together due to the principle of "like dissolves like." Although silicone rubber is a polymer, it still contains some unreacted groups, thus allowing it to undergo some cross-linking with the adhesive.

[0018] Therefore, under the dual action of cross-linking and condensation reactions, the adhesive can perfectly bond the cross-linked polyethylene and the intermediate joint together, improving the stability and reliability of the cable structure. Simultaneously, due to the occurrence of cross-linking and condensation reactions, the adhesive can interpenetrate with the surfaces of the cross-linked polyethylene and the intermediate joint, thereby filling and repairing minor scratches or pores on the surfaces of the cross-linked polyethylene and the intermediate joint, avoiding air gap defects and improving the stability of the cable in use.

[0019] Meanwhile, the adhesive has excellent waterproof properties, giving the cable superior anti-flashover protection after application. Therefore, no further waterproofing treatment is required, making it convenient to use, simple to process, and improving cable installation efficiency.

[0020] Further configuration: The additional crosslinking agent in A is one or more of the following: propyltriethoxysilane, vinyltriisopropoxysilane, methyltriisopropoxysilane, phenyltriisopropoxysilane, tetramethylguanidinopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, anilinemethyltrimethoxysilane, anilinemethyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane.

[0021] By adopting the above technical solution, the additional crosslinking agent provides a sufficient amount of alkoxy compound, which facilitates condensation reaction with terminal hydroxyl groups.

[0022] Further settings: The filler in A and B is fumed silica.

[0023] By adopting the above technical solution, fumed silica is an important nano-scale inorganic raw material with small particle size and large specific surface area. It has good dispersibility, stability and reinforcing properties, which can effectively improve the strength of the adhesive after curing. At the same time, it can be used as a catalyst carrier and its excellent dispersibility can be used to uniformly disperse the catalyst into other components, thereby improving the reaction efficiency.

[0024] Further configuration: The above-mentioned connection sealing structure for electrical transmission lines is applied to cables or optical fibers.

[0025] By adopting the above technical solutions, various power transmission line structures can be implemented.

[0026] The second objective of this invention is to provide a cable connection sealing structure that has the advantages of good fusion interface with the cable, is not prone to air gaps or sharp points, and avoids partial discharge phenomena.

[0027] A cable connection sealing structure includes a cable and a shrinkable cable accessory, wherein the cable and the shrinkable cable accessory are connected by the aforementioned electrical transmission line connection sealing structure.

[0028] Further configuration: The cold-shrink cable accessory is a cold-shrink intermediate joint.

[0029] Further configuration: The cold-shrink cable accessory is a cold-shrink cable terminal.

[0030] By adopting the above technical solutions, most cable accessory breakdown accidents are caused by substandard installation quality by installers, such as longitudinal scratches on the main insulation. When peeling off the outer semiconductive layer, excessive cutting often leaves potential air gaps on the main insulation surface. Because the knife marks left on the insulation have large microscopic gaps, void discharge can occur within the insulation, forming electrical trees that break down the insulation. The self-made adhesive layer replaces the original silicone grease coating connection with a connection that penetrates through the adhesive layer to the main insulation layer and cold-shrink joint. The adhesive layer chemically fuses cross-linked polyethylene and silicone rubber into a single structure, fundamentally eliminating the existence and possibility of air gaps, thereby improving voltage withstand performance, preventing air gap discharge, and preventing moisture from penetrating from both ends and the core to the compression interface, thus preventing breakdown accidents. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the connection and sealing structure of an electrical transmission line.

[0032] In the diagram, 1 is the structural layer; 2 is the protective layer; and 3 is the self-made adhesive layer. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings.

[0034] First preferred embodiment:

[0035] A connection sealing structure for an electrical transmission line includes a structural layer 1 made of cross-linked polyethylene on the electrical transmission line and a protective layer 2 made of silicone rubber covering the outside of the structural layer 1. The electrical transmission line can be a cable or an optical fiber.

[0036] A self-made adhesive layer 3 is provided between the structural layer 1 and the protective layer 2. The adhesive layer dissolves and bonds to the inner walls of the structural layer 1 and the protective layer 2, so that the structural layer 1 and the protective layer 2 form an integrated interface.

[0037] When the electrical transmission line is a cable, the cable connection sealing structure includes the cable and a shrinkable cable accessory. The cable and the shrinkable cable accessory are connected using the aforementioned electrical transmission line connection sealing structure. The shrinkable cable accessory is either a shrinkable intermediate joint or a shrinkable cable termination.

[0038] The cable's structural layer 1 is the main insulation layer, which has a surface treatment layer, namely a corona layer. A primer layer is also applied to the corona layer of the main insulation layer, and the material used for the primer layer is the same as that used for the self-made adhesive layer 3.

[0039] Second preferred implementation method:

[0040] Example 1:

[0041] An adhesive for cross-linked polyethylene and silicone rubber, comprising A and B, wherein,

[0042] A comprises the following components in parts by weight:

[0043] 100 parts hydroxyl silicone oil, 10 parts basic crosslinking agent, 10 parts additional crosslinking agent and 5 parts hydrophobic fumed silica;

[0044] The basic crosslinking agent consists of 2 parts methyltrimethoxysilane, 2 parts methyltriethoxysilane, 2 parts vinyltrimethoxysilane, 2 parts vinyltriethoxysilane, and 2 parts phenyltrimethoxysilane; the additional crosslinking agent consists of 2 parts propyltriethoxysilane, 2 parts vinyltriisopropoxysilane, 2 parts methyltriisopropoxysilane, 2 parts phenyltriisopropoxysilane, and 2 parts tetramethylguanidinopropyltrimethoxysilane.

[0045] B comprises the following components in parts by weight:

[0046] 100 parts of hydroxyl silicone oil, 5 parts of hydrophobic fumed silica and 0.2 parts of catalyst;

[0047] The catalyst is an organotin chelate.

[0048] The adhesive was prepared according to the above preparation method.

[0049] Example 2:

[0050] An adhesive for cross-linked polyethylene and silicone rubber, comprising A and B, wherein,

[0051] A comprises the following components in parts by weight:

[0052] 100 parts of hydroxyl silicone oil, 20 parts of basic crosslinking agent, 20 parts of additional crosslinking agent and 10 parts of hydrophobic fumed silica;

[0053] The basic crosslinking agent consists of 4 parts of methyltrimethoxysilane, 4 parts of methyltriethoxysilane, 4 parts of vinyltrimethoxysilane, 4 parts of vinyltriethoxysilane, and 4 parts of phenyltrimethoxysilane; the additional crosslinking agent consists of 4 parts of propyltriethoxysilane, 4 parts of vinyltriisopropoxysilane, 4 parts of methyltriisopropoxysilane, 4 parts of phenyltriisopropoxysilane, and 4 parts of tetramethylguanidinopropyltrimethoxysilane.

[0054] B comprises the following components in parts by weight:

[0055] 100 parts of hydroxyl silicone oil, 10 parts of hydrophobic fumed silica, and 0.3 parts of catalyst;

[0056] The catalyst is an organotin chelate.

[0057] The adhesive was prepared according to the above preparation method.

[0058] Example 3:

[0059] An adhesive for cross-linked polyethylene and silicone rubber, comprising A and B, wherein,

[0060] A comprises the following components in parts by weight:

[0061] 100 parts of hydroxyl silicone oil, 25 parts of basic crosslinking agent, 30 parts of additional crosslinking agent and 15 parts of hydrophobic fumed silica;

[0062] The basic crosslinking agent consists of 5 parts of methyltrimethoxysilane, 5 parts of methyltriethoxysilane, 5 parts of vinyltrimethoxysilane, 5 parts of vinyltriethoxysilane, and 5 parts of phenyltrimethoxysilane; the additional crosslinking agent consists of 6 parts of propyltriethoxysilane, 6 parts of vinyltriisopropoxysilane, 6 parts of methyltriisopropoxysilane, 6 parts of phenyltriisopropoxysilane, and 6 parts of tetramethylguanidinopropyltrimethoxysilane.

[0063] B comprises the following components in parts by weight:

[0064] 100 parts of hydroxyl silicone oil, 15 parts of hydrophobic fumed silica, and 0.5 parts of catalyst;

[0065] The catalyst is an organotin chelate.

[0066] The adhesive was prepared according to the above preparation method.

[0067] Example 4:

[0068] The only difference between this embodiment and Embodiment 2 is that...

[0069] The basic crosslinking agent consists of 4 parts vinyltrimethoxysilane, 4 parts vinyltriethoxysilane, 4 parts phenyltrimethoxysilane, 4 parts phenyltriethoxysilane, and 4 parts aminopropyltrimethoxysilane.

[0070] Example 5:

[0071] The only difference between this embodiment and Embodiment 2 is that...

[0072] The basic crosslinking agent consists of 10 parts of methyltrimethoxysilane and 10 parts of aminopropyltrimethoxysilane.

[0073] Example 6:

[0074] The only difference between this embodiment and Embodiment 2 is that...

[0075] The additional crosslinking agent consists of 4 parts of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 4 parts of γ-(2,3-epoxypropoxy)propyltriethoxysilane, 4 parts of γ-methacryloyloxypropyltrimethoxysilane, 4 parts of anilinemethyltrimethoxysilane, and 4 parts of anilinemethyltriethoxysilane.

[0076] Example 7:

[0077] The only difference between this embodiment and Embodiment 2 is that...

[0078] The additional crosslinking agent consists of 4 parts of aniline methyltriethoxysilane, 4 parts of aminoethylaminopropylmethyldimethoxysilane, 4 parts of diethylaminomethyltriethoxysilane, 4 parts of γ-methacryloyloxypropyltrimethoxysilane, and 4 parts of γ-methacryloyloxypropylmethyldimethoxysilane.

[0079] Example 8:

[0080] The only difference between this embodiment and Embodiment 2 is that...

[0081] The additional crosslinking agent consists of 5 parts of propyltriethoxysilane isocyanate, 5 parts of vinyltriisopropoxysilane, 5 parts of methyltriisopropoxysilane, and 5 parts of phenyltriisopropoxysilane.

[0082] Example 9:

[0083] The only difference between this embodiment and Embodiment 2 is that...

[0084] The catalyst is a guanidine-based catalyst.

[0085] Example 10:

[0086] The only difference between this embodiment and Embodiment 2 is that...

[0087] The catalyst is a silane catalyst.

[0088] Comparative Example 1:

[0089] The only difference between this comparative example and Example 2 is that A does not contain a basic crosslinking agent.

[0090] Comparative Example 2:

[0091] The only difference between this comparative example and Example 2 is that A does not contain an additional crosslinking agent.

[0092] Comparative Example 3:

[0093] This comparative example differs from Example 2 only in that A includes 50 parts of a basic crosslinking agent;

[0094] The basic crosslinking agent consists of 10 parts of methyltrimethoxysilane, 10 parts of methyltriethoxysilane, 10 parts of vinyltrimethoxysilane, 10 parts of vinyltriethoxysilane, and 10 parts of phenyltrimethoxysilane.

[0095] Comparative Example 4:

[0096] The only difference between this comparative example and Example 2 is that A includes 50 parts of an additional crosslinking agent;

[0097] The additional crosslinking agent consists of 10 parts of propyltriethoxysilane, 10 parts of vinyltriisopropoxysilane, 10 parts of methyltriisopropoxysilane, 10 parts of phenyltriisopropoxysilane, and 10 parts of tetramethylguanidinopropyltrimethoxysilane.

[0098] Comparative Example 5:

[0099] The only difference between this comparative example and Example 2 is that the catalyst in B is 10 parts.

[0100] Examples 1-5 and Comparative Examples 1-3 all used the first preparation method and the first usage method; Examples 6-10 and Comparative Examples 4-5 all used the second preparation method and the second usage method.

[0101] Comparative Example 6:

[0102] Kraft 704 adhesive was purchased from Guangdong Hengda New Material Technology Co., Ltd.

[0103] Comparative Example 7:

[0104] Kraft 703 adhesive was purchased from Guangdong Hengda New Material Technology Co., Ltd.

[0105] Comparative Example 8:

[0106] 3140 adhesive purchased from Dow Corning Incorporated, USA.

[0107] V. Performance Testing:

[0108] 1. Testing items and test basis:

[0109] 1-1: Dielectric constant test: Refer to GB / T 1409-2006 "Recommended methods for measuring the permittivity and dielectric loss factor of electrical insulation materials at power frequency, audio frequency and high frequency (including meter wave wavelength)";

[0110] 1-2: Insulation strength testing: Refer to GB / T 1408 "Test Methods for Electrical Strength of Insulating Materials";

[0111] 1-3: Elongation test: Refer to HG / T 3849-2008 "Determination of tensile strength and elongation at break of rigid rubber";

[0112] 1-4: Shear strength test: Refer to GB / T 7124-2008 "Determination of tensile shear strength of adhesives (rigid material to rigid material)";

[0113] 1-5: Peel strength test: Refer to GB / T 2791-1995 "Adhesives T Peel Strength Test Method Flexible Materials to Flexible Materials".

[0114]

[0115]

[0116] As can be seen from the table above, the cross-linked polyethylene and silicone rubber adhesive prepared by the preparation method of this application has good mechanical properties, especially glass strength, compared with those commonly used by those skilled in the art in the prior art. It has outstanding performance advantages compared with similar products, while ensuring excellent insulation properties.

[0117] The above embodiments are merely explanations of the present invention and are not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to these embodiments without contributing any inventive step, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A connection sealing structure for an electrical transmission line, comprising a structural layer (1) made of cross-linked polyethylene on the electrical transmission line, and a protective layer (2) made of silicone rubber covering the outside of the structural layer (1), characterized in that: A self-made adhesive layer (3) is provided between the structural layer (1) and the protective layer (2). The adhesive layer dissolves and combines on the inner wall of the structural layer (1) and the protective layer (2), so that the structural layer (1) and the protective layer (2) form an integrated interface. The self-made adhesive layer comprises A and B. A comprises the following components in parts by weight: 100 parts of base polymer, 10-25 parts of base crosslinking agent, 10-30 parts of additional crosslinking agent, and 5-15 parts of filler; the base crosslinking agent is one or more of methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and aminopropyltrimethoxysilane; B comprises the following components in parts by weight: 100 parts of base polymer, 5-15 parts of filler, and 0.2-0.5 parts of catalyst; wherein the base polymer in A and B is hydroxyl silicone oil. The additional crosslinking agent in A is one or more of the following: propyltriethoxysilane, vinyltriisopropoxysilane, methyltriisopropoxysilane, phenyltriisopropoxysilane, tetramethylguanidinopropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, anilinemethyltrimethoxysilane, anilinemethyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, diethylaminomethyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane. The filler in A and B is fumed silica.

2. The connection sealing structure for the electrical transmission line according to claim 1, characterized in that: The structural layer (1) has a surface treatment layer, which is a corona layer.

3. The connection sealing structure for the electrical transmission line according to claim 2, characterized in that: The structural layer (1) has a surface treatment layer, which is a base coating layer on the structural layer (1). The material used for the base coating layer is the same as the material used for the self-made adhesive layer (3).

4. The connection sealing structure for electrical transmission lines according to any one of claims 1 to 3, characterized in that: Apply to cables or optical fibers.

5. A cable connection sealing structure, comprising a cable and a cold-shrink cable accessory, characterized in that: The cable and the cold-shrink cable accessory are connected by the sealing structure of the electrical transmission line as described in any one of claims 1 to 3.

6. The cable connection sealing structure according to claim 5, characterized in that: The shrinkable cable accessory is a shrinkable intermediate joint.

7. The cable connection sealing structure according to claim 5, characterized in that: The shrinkable cable accessory is a shrinkable cable terminal.

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