Submarine cable, and preparation method therefor and use thereof

Abstract

A submarine cable, and a preparation method therefor and the use thereof. The submarine cable comprises an insulating layer. The insulating layer is made of polyethylene, a vulcanizing agent and an antioxidant, wherein the vulcanizing agent is dicumyl peroxide; the antioxidant is pentaerythritol tetraester; and the mass ratio of the low-density linear polyethylene to the vulcanizing agent to the antioxidant is (100):(0.8-2.5):(0.1-0.4). The insulating material is prepared from the specific vulcanizing agent and antioxidant; and compared with a conventional insulating material in the prior art, the operating temperature of the insulating material is increased to 105°C from 90°C, thereby significantly improving the reliability, stability and transmission capacity of the submarine cable.

Description

A submarine cable and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 9, 2023, with application number 202311486890.7 and application name “A submarine cable, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of communication facilities, and in particular to a submarine cable and a preparation method and application thereof. Background Art

[0003] Submarine cables are communications systems that connect two locations via optical or electrical cables under the sea. They are primarily used for long-distance communications, such as those across oceans and straits. Submarine cables are a crucial component of modern communications technology and are crucial for advancing global informatization and promoting regional economic development.

[0004] Submarine cables typically consist of multiple components, including a cable core, coating, insulation, outer sheath, connectors, plugs, and terminal equipment. The cable core, consisting of multiple strands of copper wire or optical fiber, is the core component responsible for signal transmission. The coating or insulation protects the cable core from contact with seawater, potentially causing short circuits or data loss. The outer sheath protects the cable, enabling it to withstand the harsh conditions of the submarine environment. Connectors and plugs are essential components of the cable, connecting it to devices. Terminal equipment converts submarine cable signals into understandable information and performs related processing.

[0005] Currently, submarine cables commonly use cross-linked polyethylene (XLPE) as the primary insulation layer. The maximum permissible long-term operating temperature for cables insulated with XLPE is 90°C. The International Electrotechnical Commission (IEC) standard IEC 60216-1 stipulates that the recommended short-term overload temperature for XLPE is 130°C, and operation at this temperature should not exceed 100 hours. The maximum operating temperature is 160°C, and operation should not exceed 50 hours, resulting in a thermal lifespan of up to 40 years. Because the current carrying capacity of submarine cables is directly related to the maximum operating temperature of the conductor, the long-term heat resistance of the insulation material imposes certain limitations on the transmission capacity of submarine cables. As demand for submarine cable transmission capacity continues to increase, so too does the maximum heat resistance of submarine cable insulation.

[0006] Summary of the Invention

[0007] To solve the problems existing in the prior art, the present application provides a submarine cable and its preparation method and application. The present application uses a specific vulcanizing agent and antioxidant to prepare an insulation layer material with significantly increased operating temperature, which can significantly increase the capacity of the submarine cable.

[0008] In a first aspect, the present application provides an insulating material comprising: polyethylene, a vulcanizing agent, and an antioxidant;

[0009] The vulcanizing agent is dicumyl peroxide;

[0010] The antioxidant is pentaerythritol ester;

[0011] The mass ratio of the polyethylene, the vulcanizing agent and the antioxidant is (100): (0.8-2.5): (0.1-0.4).

[0012] Optionally, the mass ratio of the polyethylene, the vulcanizing agent and the antioxidant is (100): (1.3-1.9): (0.15-0.31).

[0013] The maximum long-term operating temperature of conventional cross-linked polyethylene insulation materials in the prior art is only 90°C, which affects the current that the submarine cable can carry and thus affects the current carrying capacity.

[0014] The present application provides a cross-linked polyethylene insulation material prepared using a specific vulcanizing agent and antioxidant, wherein the long-term operating temperature is increased to above 105°C, and the tensile strength before aging is ≥17 MPa, the elongation at break is ≥500%, the volume resistivity (23°C) is ≥1.0×1016Ω·m, the dielectric constant is ≤2.3-2.35, the dielectric loss tangent tgδ∈(0.0005, 0.001), the short-time power frequency breakdown strength (23°C) is ≥40 kV / mm, and the melt flow rate (190°C / 2.16kg) is between 0.7 and 1.1. Optionally, the performance is better when the melt flow rate is 0.95.

[0015] In addition, the vulcanizing agent content has a significant impact on the insulation properties of cross-linked polyethylene. If the content is too low, the cross-linking production efficiency of the material cannot be met, and the cross-linking degree is insufficient, which in turn affects the mechanical properties and temperature resistance; if the content is too high, it will cause the material to be over-cross-linked and the output of cross-linking by-products will increase, which is not conducive to product quality control.

[0016] The content of antioxidants has a significant impact on the electrical, thermal and mechanical properties of insulation. At the same time, the mechanism of action of antioxidants is to remove active free radicals in polymers, so it also has a significant impact on the cross-linking reaction of materials.

[0017] Optionally, the polyethylene is low-density polyethylene, and its mass percentage in the insulating material is 80-95%.

[0018] Optionally, the antioxidant is pentaerythritol 1010 or pentaerythritol 1035.

[0019] Optionally, a scorch retardant and a plasticizer are also included.

[0020] Optionally, the scorch inhibitor includes one or more of benzoic acid, phthalic anhydride or N-cyclohexylthiophthalimide; and the plasticizer includes one or more of 2-naphthol, dimethylthiophenol or pentachlorothiophenol.

[0021] Optionally, the insulating material includes, by weight, 100 parts of polyethylene, 0.8-2.5 parts of a vulcanizing agent, 0.1-0.4 parts of an antioxidant, 0.4-1.2 parts of a scorch inhibitor, and 0.8-2 parts of a plasticizer.

[0022] In a second aspect, the present application provides a submarine cable, comprising an optical fiber unit and a conductor; the optical fiber unit is wrapped by the conductor.

[0023] At the same time, during normal operation of current fiber-optic composite submarine cables, the optical fiber unit is generally placed within the gaps filled with the outer layer of the cable, making it impossible to accurately measure its operating temperature. This will adversely affect the subsequent operation and maintenance of the submarine cable. However, this application places the optical fiber unit within the conductor, which can accurately measure the operating temperature of the submarine cable through the optical fiber, facilitating the precise location of the fault.

[0024] Optionally, the conductor includes an inner conductor and an outer conductor; the outer conductor is one or more of a trapezoidal stranded conductor, an SZ-type stranded conductor or a split stranded conductor.

[0025] Optionally, the raw material of the conductor includes one or more of copper, tinned copper, aluminum or aluminum alloy.

[0026] Optionally, a cooling device is also included.

[0027] The present application further provides a cooling pipe in the submarine cable, which can be provided in the filling layer to cool down the operating temperature after it exceeds a certain threshold to prevent overheating.

[0028] Optionally, the insulating layer in the submarine cable is prepared using the insulating material.

[0029] Optionally, in the submarine cable, a conductor shielding layer, an insulating layer, an insulating shielding layer, a water-blocking layer, a metal shielding layer, and a non-metallic sheath layer are sequentially provided outside the conductor.

[0030] Optionally, after the core and the filling layer in the submarine cable are twisted together, they are sequentially covered with a tape layer, an inner cushion layer, an armor layer and an outer layer.

[0031] Optionally, the conductor shielding layer and the insulating shielding layer are made of ethylene-vinyl acetate copolymer with carbon black added thereto, and a heat-resistant vulcanizing agent is added during the preparation process.

[0032] Optionally, the conductor shielding layer, the insulating layer and the insulating shielding layer are prepared by a three-layer co-extrusion method, and the specific process is as follows:

[0033] The conductor core is preheated to 70-120°C, and the conductor shielding layer, the insulating layer and the insulating shielding layer are sequentially extruded by a three-layer co-extrusion method.

[0034] Optionally, the water-blocking layer is a semiconductor water-blocking tape.

[0035] Optionally, the metal shielding layer includes one or more of an alloy lead sheath, a copper belt, a copper wire, and a copper tube.

[0036] Optionally, a cooling device is further included; the cooling device is arranged between the filling materials.

[0037] Optionally, the cooling device is a cooling liquid pipeline, an inert gas cooling pipeline or a magnetic cooling device.

[0038] The liquid cooling pipe operates as follows: a temperature exceeding 70°C triggers the coolant device, which can be water, mineral oil, or electronic fluoride liquid. The inert gas is nitrogen or carbon dioxide. The magnetic cooling device utilizes a magnetic field to cool materials, reducing their internal heat and lowering their temperature. This cooling mechanism is based on the coupled entropy change effect (MCE), whereby the application of a magnetic field to a material alters its thermodynamic properties, leading to a change in the material's thermodynamic entropy. This effect is particularly effective when the cable's armor is magnetic.

[0039] In summary, the configuration of the optical fiber unit and the cooling device provided in the present application can reflect the temperature of the optical fiber unit very promptly, thereby effectively improving the problem of decreased current carrying capacity caused by excessively high cable temperature.

[0040] Optionally, the wrapping tape is a rubber-coated cotton tape or an environmentally friendly cotton tape.

[0041] Optionally, the material of the inner cushion layer is polypropylene.

[0042] Optionally, the material of the armor layer includes one or more of galvanized steel wire, hard copper wire, stainless steel wire or aluminum alloy wire.

[0043] Optionally, the material of the outer layer is polypropylene.

[0044] The present application further provides an application of the submarine cable in improving the accuracy of fault location or detecting the accuracy of operating temperature.

[0045] This application has the following beneficial effects:

[0046] This application utilizes specific vulcanizing agents and antioxidants to improve existing insulation materials, resulting in an insulation material with a significantly higher operating temperature, exceeding 105°C compared to the existing 90°C. The insulation material provided by this application exhibits a higher operating temperature, significantly increasing the current that submarine cables can carry, improving their capacity and service life, and possessing high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a schematic diagram of the overall structure of a submarine cable provided in Example 2 of the present application;

[0048] FIG2 is a schematic diagram of the structure of a first optical fiber unit provided in Example 2 of the present application;

[0049] FIG3 is a schematic diagram of the structure of a second optical fiber unit provided in Example 2 of the present application;

[0050] FIG4 is a schematic diagram of the structure of the third optical fiber unit provided in Example 2 of the present application.

[0051] Reference numerals:

[0052] 1: Optical fiber unit; 2: Water-blocking conductor; 21: Inner compressed round conductor; 201: Outer T-type conductor; 202: Outer SZ-type conductor; 203: Outer split conductor; 3: Conductor shielding layer; 4: Insulation layer; 5: Insulation shielding layer; 6: Water-blocking layer; 7: Metal shielding layer; 8: Non-metallic sheath layer; 9: Cooling device; 10: Filling layer; 11: Tape layer; 12: Inner cushion layer; 13: Armor layer; 14: Outer layer. DETAILED DESCRIPTION

[0053] Example 1

[0054] This embodiment provides an insulating material, including the following components:

[0055] 100 parts of low-density polyethylene, 0.8-2.5 parts of vulcanizing agent, 0.1-0.4 parts of antioxidant, 0.4-1.2 parts of scorch inhibitor, and 0.8-2 parts of plasticizer.

[0056] The preparation method of the insulating material is as follows:

[0057] A polyethylene mixture formed by low-density polyethylene, a vulcanizing agent, an antioxidant, a scorch inhibitor, a plasticizer, etc. is hot-pressed according to a proportion and then vulcanized to obtain a cross-linked polyethylene insulation layer material.

[0058] According to the above method, various insulating materials are obtained in this embodiment as follows:

[0059] Insulation material 1-1: 100 parts of low-density polyethylene, 1 part of vulcanizing agent, 0.1 part of antioxidant, 0.8 part of scorch inhibitor, and 0.8 part of plasticizer.

[0060] Insulation material 1-2: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.1 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0061] Insulation material 1-3: 100 parts of low-density polyethylene, 2.5 parts of vulcanizing agent, 0.1 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0062] Comparative material 1-4: 100 parts of low-density polyethylene, 2.8 parts of vulcanizing agent, 0.1 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0063] In the above materials, the curing agent is dicumyl peroxide (DCP); the antioxidant is pentaerythritol 1035; the antiscorching agent is N-cyclohexylthiophthalimide (CTP); and the plasticizer is 2-naphtholthiophenol.

[0064] Comparative material 1-5: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.1 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0065] The curing agent is dibenzoyl peroxide (BPO), the antioxidant is pentaerythritol 1035, the scorch inhibitor is N-cyclohexylthiophthalimide, and the plasticizer is 2-naphtholthiophenol.

[0066] Insulation material 2-1: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.2 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer.

[0067] Insulation material 2-2: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0068] Insulation material 2-3: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.4 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0069] Comparative material 2-4: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.5 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0070] The curing agent is dicumyl peroxide DCP; the antioxidant is pentaerythritol 1035; the scorch inhibitor is N-cyclohexylthiophthalimide; and the plasticizer is 2-naphtholthiophenol.

[0071] Comparative material 2-5: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 0.8 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0072] The curing agent is dicumyl peroxide DCP; the antioxidant is pentaerythritol 1035; the scorch retarder is phthalic anhydride; and the plasticizer is pentachlorothiophenol.

[0073] Insulation material 3-1: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 0.4 parts of scorch inhibitor, and 0.8 parts of plasticizer.

[0074] Insulation material 3-2: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0075] Insulation material 3-3: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.2 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0076] Comparative material 3-4: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.6 parts of scorch inhibitor, and 0.8 parts of plasticizer;

[0077] The curing agent is dicumyl peroxide (DCP); the antioxidant is pentaerythritol 1035; the scorch inhibitor is N-cyclohexylthiophthalimide; and the plasticizer is 2-naphthylthiophenol.

[0078] Insulation material 4-1: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 1.0 parts of plasticizer.

[0079] Insulation material 4-2: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 1.5 parts of plasticizer;

[0080] Insulation material 4-3: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 2.0 parts of plasticizer;

[0081] Comparative edge material 4-4: 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 2.5 parts of plasticizer;

[0082] The curing agent is dicumyl peroxide DCP; the antioxidant is pentaerythritol 1035; the scorch inhibitor is N-cyclohexylthiophthalimide; and the plasticizer is 2-naphtholthiophenol.

[0083] Insulation material 5:

[0084] 100 parts of low-density polyethylene, 1.8 parts of vulcanizing agent, 0.3 parts of antioxidant, 1.0 parts of scorch inhibitor, and 1.5 parts of plasticizer.

[0085] The curing agent is dicumyl peroxide DCP; the antioxidant is pentaerythritol 1010; the scorch inhibitor is N-cyclohexylthiophthalimide; and the plasticizer is 2-naphtholthiophenol.

[0086] In this example, the above-mentioned insulating materials and the control group materials were subjected to a hot elongation test. The test samples were prepared according to the standard GB / T2951.11-2008: the sample length was 100 mm, the dumbbell-shaped test piece thickness was not less than 0.8 mm and not more than 2.0 mm, and a marking line L0 was marked in the middle of each sample with a spacing of 20 mm. After the sample preparation was completed, the hot elongation test was carried out according to the above-mentioned standard. The results are shown in the following table:

[0087] Table 1 Thermal extension test results of different insulation materials and control group

[0088] The test results in Table 1 show that insulation material 4-2 exhibits significantly improved thermal elongation compared to the other insulation materials. Insulation material 5, the control group, which replaced the antioxidant, met the requirements of the relevant cross-linked polyethylene insulated submarine cable standards, but its thermal elongation performance was slightly inferior to that of insulation material 4-2. Therefore, insulation material 4-2 is significantly superior in terms of toughness, flexibility, and heat resistance.

[0089] Example 2

[0090] This embodiment provides a submarine cable, the specific structure of which is shown in FIG1 , wherein:

[0091] The optical fiber unit 1 serves as the center line within the water-blocking conductor 2. The optical fiber unit 1 can be a conventional optical fiber unit in the prior art, such as a single-mode optical fiber, a multimode optical fiber, or a hybrid of the two. The optical fiber unit 1 is covered with an extruded sheath having a thickness of 0.5-1 mm.

[0092] The water-blocking conductor 2 is located on the outer layer of the optical fiber unit 1 and can be a combination of one or more of water-blocking glue, water-blocking powder, water-blocking yarn, and water-blocking tape. The structure of the water-blocking conductor 2 is divided into two layers, inner and outer. For example, as shown in Figures 2-4, three different water-blocking conductor structures are listed. In Figure 2, an inner layer of compacted circular conductor 21 and an outer layer of T-shaped conductor 201, that is, a trapezoidal stranded conductor, are sequentially arranged outside the optical fiber unit 1; Figure 3 shows an inner layer of compacted circular conductor 21 and an outer layer of SZ-shaped conductor 202, respectively, outside the optical fiber unit 1; and Figure 4 shows an inner layer of compacted circular conductor 21 and an outer layer of segmented conductor 203, respectively, outside the optical fiber unit 1.

[0093] Optionally, the material of the water-blocking conductor 2 may be one or more of copper, tinned copper, aluminum or aluminum alloy.

[0094] A conductor shielding layer 3 is provided outside the water-blocking conductor 2, and an insulating layer 4 is coated on the conductor shielding layer 3. Insulating layer 4 can be made of existing insulating materials, such as cross-linked polyethylene (XLPE) or ethylene propylene rubber (EPR). However, the maximum allowable operating temperature of existing XLPE insulation is 90°C. Since the current carrying capacity of submarine cables is directly related to the maximum operating temperature of the conductor, the heat resistance of existing insulation materials imposes a certain degree of limitation on the transmission capacity of submarine cables.

[0095] Therefore, the insulating material provided in the aforementioned embodiments 1-3 can be optionally used to prepare the insulating layer 4. The tensile strength of the material before aging is ≥17Mpa, the elongation at break is ≥500%, the volume resistivity (23°C) is ≥1.0×1016Ω·m, the dielectric constant is ≤2.3-2.35, the dielectric loss tangent tgδ∈(0.0005, 0.001), the short-time power frequency breakdown strength (23°C) is ≥40kV / mm, and the melt flow rate (190°C / 2.16kg) is between 0.7-1.1.

[0096] Optionally, when the melt flow rate is 0.95, the performance is better.

[0097] The insulating shielding layer 5 is extruded over the insulating layer 4. The conductor shielding layer 3, insulating layer 4, and insulating shielding layer 5 are extruded simultaneously using a three-layer co-extrusion process. For example, the conductor shielding layer 3 and insulating shielding layer 5 are made of ethylene-vinyl acetate copolymer with carbon black added, and a heat-resistant vulcanizing agent is added to the material.

[0098] Optionally, the three-layer co-extrusion process is as follows:

[0099] The conductor core is induction heated in the temperature range of 70℃-120℃. Optional preheating temperature is 110℃ and post-preheating temperature is 80℃. The surface temperature of the conductor is detected. If it is within the set range, it meets the requirements and the extrusion machine can be started.

[0100] The conductor shielding layer, insulation layer and insulation shielding layer are extruded in sequence on the surface of the conductor core by three-layer co-extrusion to form an insulated wire core. The extruder temperature is set as follows:

[0101] Table 2 Extruder temperature settings

[0102] The mesh numbers of the conductor shielding and insulation shielding filters are a combination of 40 mesh / 80 mesh / 150 mesh, 200 mesh, 80 mesh / 40 mesh, and the insulation layer is a combination of 20 mesh / 80 mesh / 200 mesh / 400 mesh / 80 mesh / 20 mesh.

[0103] Due to the heat resistance of the insulation material, its mold matching formula is set as:

[0104] Mold core: D1 = conductor outer diameter + (0.6-1.8) mm; the coefficients of the compressed circle and the profile are slightly different. The profile has a larger outer diameter and its surface roundness control process is not as good as that of the compressed circle conductor. To avoid die jamming and downtime, the profile coefficient is set slightly larger than that of the compressed circle conductor.

[0105] Liner mold: D2 = inner screen outer diameter + (0.1-1.2) mm; the increase coefficients of VCV and CCV are also different. When using VCV production, the insulation thickness is slightly larger, so the coefficient is greater than the CCV coefficient.

[0106] Die sleeve: D3 = conductor diameter + 2 × inner screen thickness + 2 × insulation thickness × (1.1-1.2) + 2 × outer screen thickness;

[0107] The insulated wire core is cross-linked in a cross-linking pipe at a temperature of 200-300°C and a nitrogen pressure greater than 10Mpa, so that the maximum surface temperature of the insulating shielding layer is controlled below 250°C to prevent scorching.

[0108] A water-blocking layer 6 is provided outside the insulating shielding layer 5 . The water-blocking layer 6 is a semiconductor water-blocking tape, which can be a single-sided water-blocking tape, a double-sided water-blocking tape, or a combination thereof.

[0109] A metal shielding layer 7 is provided outside the water-blocking layer 6. The metal shielding layer 7 may be a combination of one or more of an alloy lead sheath, a copper belt, a copper wire, and a copper tube.

[0110] A non-metallic sheath layer 8 is provided outside the metal shielding layer 7. The non-metallic sheath layer 8 is one of a semi-conductive PE sheath and an insulating PE sheath.

[0111] Optionally, in the submarine cable, a cooling device 9 is provided outside the optical fiber unit 1 and its outer covering multi-layer material, so that when the cable temperature is greater than 75° C., the system can be automatically cooled by methods including but not limited to liquid nitrogen cooling.

[0112] Optionally, in the submarine cable, outside the optical fiber unit 1 and the multi-layer material covering it, and outside the cooling device 9, there is a filling layer 10, and the filling layer 10 contains conventional filling materials, such as polyethylene foam, polyurethane foam or silicone, which can be filling strips or filling ropes; the cooling device 9 can be a cooling liquid pipe, an inert gas cooling pipe or a magnetic cooling device.

[0113] Optionally, the outer covering layer of the submarine cable is composed of a tape layer 11, an inner cushion layer 12, an armor layer 13 and an outer layer 14. The tape layer 11 is a rubber-coated cotton tape or an environmentally friendly cotton tape, the inner cushion layer 12 is a polypropylene (PP) material, the armor layer 13 can be galvanized steel wire, hard copper wire, stainless steel wire, or aluminum alloy wire, and the outer layer 14 can be a polypropylene (PP) material.

[0114] Example 3

[0115] Based on the submarine cable provided in Example 2, this example verifies the performance of submarine cables prepared using different insulation layer materials. Specifically, experimental and control groups are set up, wherein experimental groups 1-1 to 1-3 use insulation materials 1-1 to 1-3 in Example 1, respectively; experimental groups 2-1 to 2-3 use insulation materials 2-1 to 2-3 in Example 1, respectively; experimental groups 3-1 to 3-3 use insulation materials 3-1 to 3-3 in Example 1, respectively; experimental groups 4-1 to 4-3 use insulation materials 4-1 to 4-3 in Example 1, respectively; and experimental group 5 uses insulation material 5 in Example 1. Control groups 1-4 and 1-5 use comparative materials 1-4 and 1-5 in Example 1; control groups 2-4 and 2-5 use comparative materials 2-4 and 2-5 in Example 1; control group 3-4 uses comparative material 3-4 in Example 1; and control group 4-4 uses comparative material 4-4 in Example 1.

[0116] The remaining materials are selected as follows: the optical fiber unit 1 is a single-mode optical fiber; the water-blocking conductor 2 is a copper conductor; the conductor shielding layer 3 and the insulating shielding layer 5 are cross-linkable semi-conductive shielding, the material of which is ethylene-vinyl acetate copolymer with carbon black added; the water-blocking layer 6 is a semi-conductive water-resistant tape; the metal shielding layer 7 is an alloy lead sheath; the non-metallic sheath layer 8 is a semi-conductive PE sheath; the cooling device 9 is a magnetic cooling device; the filling layer 10 is a filling strip; the wrapping tape 11 is an environmentally friendly cotton cloth tape; the inner pad 12 is made of polypropylene; the armor layer 13 is galvanized steel wire; and the outer layer 14 is made of polypropylene.

[0117] The following electrical performance experiment 1 was conducted for the above experimental group and control group:

[0118] Thermal Cycle Test Voltage Test: Each test consists of a minimum of 8 hours of heating followed by at least 16 hours of natural cooling. The conductor temperature is heated by current to 105°C-110°C. During each thermal cycle, the conductor temperature must be maintained at 105°C-110°C for at least 2 hours. Heating and cooling cycles are repeated 20 times. A voltage of 2U0kV (rated voltage) is applied to the specimen throughout the test. No breakdown occurs during the test.

[0119] Further conduct the following electrical performance experiment 2:

[0120] Partial Discharge Test: Conduct a partial discharge test on the wire core that has undergone the thermal cycling voltage test. The test environment is (20±15)°C, and the test sensitivity is 5pC or better. The test voltage is gradually increased to 1.75U0, maintained for 10 seconds, and then reduced to 1.5U0. During the test, no measurable discharge exceeding the declared sensitivity is observed.

[0121] The results of the electrical performance test are shown in the following table:

[0122] Table 3 Electrical performance test results

[0123] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An insulating material, characterized in that: include: Polyethylene, vulcanizing agent and antioxidant; The vulcanizing agent is dicumyl peroxide; The antioxidant is pentaerythritol ester; The mass ratio of the polyethylene, the vulcanizing agent and the antioxidant is 100:(0.8-2.5):(0.1-0.4).

2. The insulating material according to claim 1, characterized in that The polyethylene is low-density linear polyethylene, and its fraction ratio in the insulating material is 100 parts.

3. The insulating material according to claim 1, characterized in that The antioxidant is pentaerythritol ester 1010 or pentaerythritol ester 1035.

4. The insulating material according to any one of claims 1 to 3, characterized in that: Also includes scorch retardants and plasticizers.

5. The insulating material according to claim 4, characterized in that In parts by weight, it includes: 100 parts of polyethylene, 0.8-2.5 parts of vulcanizer, 0.1-0.4 parts of antioxidant, 0.4-1.2 parts of scorch inhibitor and 0.8-2 parts of plasticizer.

6. A submarine cable, characterized in that: The submarine cable uses the insulating material described in any one of claims 1 to 5 as an insulating layer.

7. A submarine cable, characterized in that: The submarine cable comprises an optical fiber unit and a conductor; the optical fiber unit is wrapped by the conductor.

8. The submarine cable according to claim 7, characterized in that: The conductor comprises an inner conductor and an outer conductor; the outer conductor is one or more of a trapezoidal stranded conductor, an SZ-type stranded conductor or a split stranded conductor.

9. The submarine cable according to claim 7 or 8, characterized in that: It also includes a cooling device and a filling material; the cooling device is arranged between the filling materials.

10. Use of the insulating material according to any one of claims 1 to 5 in increasing the operating temperature of a submarine cable.

11. Use of the submarine cable according to any one of claims 7 to 9 in improving the accuracy of fault location or the accuracy of detecting operating temperature.

Images