10kV medium-voltage fireproof single-core power cable

Abstract

The utility model discloses a 10kV medium-voltage fireproof single-core power cable which comprises a body, the inner layer of the body is only provided with a conductor (1), the outer layer of the body is provided with a multifunctional isolation layer (4), and the multifunctional isolation layer (4) comprises a second heat insulation layer (2), an oxygen isolation layer (3), an isolation layer (4), a first heat insulation layer (5) and an outer protection layer (6) from inside to outside. The second heat insulation layer (2) and the first heat insulation layer (5) are used for heat insulation, the oxygen isolation layer (3) and the outer protection layer (6) are used for flame retardance, and the isolation layer (4) is used for high-temperature isolation. The utility model relates to a 10kV medium-voltage fireproof single-core power cable which is suitable for a single-core structure and ensures that the power cable can pass a fireproof test.

Description

Technical Field

[0001] The utility model relates to the field of cables, in particular to a 10kV medium-voltage fire-resistant single-core power cable. Background Art

[0002] In recent years, with the rapid economic development, various engineering projects have increasingly higher requirements for the safety level of distribution lines. Places with dense populations, high-rise buildings and other fire hazards pay more attention to the selection of cables. Based on this background, cables with fire-resistant requirements are selected and used by more and more customers.

[0003] At present, the main test objects involved in fire resistance tests in the wire and cable industry include medium and low voltage power cables. However, the fire resistance test methods of the two types of cables are different. Low voltage power cables are required to operate normally in the test circuit with rated voltage after 90 minutes of fire supply; while medium voltage cables are required to undergo power frequency withstand voltage test after cooling after 90 minutes of fire supply. The test conditions are more stringent, so the current pass rate of medium voltage fire resistant power cables in the industry is not high.

[0004] At the same time, power cables are divided into armored power cables and non-armored power cables according to whether they are equipped with an armor layer. The armor layer is mainly composed of steel belt, copper belt and aluminum belt, which plays a role in bearing mechanical stress during the use of the cable, and in the fire resistance test, it mainly plays the effect of cooling the metal after the test. Therefore, in comparison, armored power cables are easier to pass the fire resistance test. Non-armored cables are more difficult to pass the test because they do not have this metal layer in their structure, but the design of the armor structure will reduce production efficiency and increase costs.

[0005] In addition, in the fire resistance test, the probability of passing the test for multi-core cables and single-core cables is different. The outer diameter of the single-core cable is smaller than that of the multi-core cable. Under the same test conditions, the flame is relatively more concentrated, and the total conductor area is small. The proportion of non-metallic materials becomes larger, making it more difficult for single-core cables to pass the test. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a non-armored 10kV medium-voltage fire-resistant single-core power cable suitable for a single-core structure and capable of passing a fire-resistant test.

[0007] The technical solution adopted by the utility model to solve the above-mentioned problem is: a 10kV medium-voltage fire-resistant single-core power cable, comprising a body, the inner layer of the body is provided with only one conductor, the outer layer of the body is provided with a multifunctional isolation layer, the multifunctional isolation layer comprises from the inside to the outside a second thermal insulation layer, an oxygen isolation layer, an isolation layer, a first thermal insulation layer and an outer protective layer, the second thermal insulation layer and the first thermal insulation layer are used for thermal insulation, the oxygen isolation layer and the outer protective layer are used for flame retardancy, and the isolation layer is used for high-temperature isolation.

[0008] Compared with the prior art, the advantages of the utility model are: through the design of the multifunctional isolation layer, it is ensured that the cable has double heat insulation and flame retardant capabilities, so that there is no need for the armor layer to provide a cooling effect for the fire resistance test, so as to reduce the design of the armor layer, and the design of conventional fireproof mud can be reduced, so that the cable has better bending performance, which is convenient for the transportation and laying of the cable; at the same time, because of the design of the multifunctional isolation layer, it is difficult for the flame to break through the isolation of the multifunctional isolation layer in the fire resistance test, so there is no need to worry about the concentration of flames on the conductor, whether it is a multi-core conductor or a single-core conductor, it is easy to pass the fire resistance test; similarly, the conductor shielding layer, insulating layer, insulating shielding layer, buffer layer, metal shielding layer and other structures between the conductor and the multifunctional isolation layer will not be affected by the fire resistance test, and will not cause deformation, melting and other phenomena of these structures due to the high temperature environment, thereby ensuring that the cable can still guarantee the qualified rate of the cable during the power frequency withstand voltage test.

[0009] As an improvement of the present invention, the second thermal insulation layer is composed of multiple layers of overlapping mesh glass fiber tapes, and the overlapping coverage rate of each layer is not less than 15%. Through the improvement, the glass fiber has a better thermal insulation effect, and the mesh glass fiber has higher strength than traditional glass fiber, so that the cable structure is more stable. In the absence of an armor layer to withstand mechanical stress, the cable structure can also be stable. The design of each layer overlapping coverage rate of not less than 15% ensures the comprehensive coverage of the second thermal insulation layer and avoids the omission of the wrapping area. At the same time, it can also ensure that when the cable is bent, the two overlapping layers of mesh glass fiber are not separated, and the comprehensive coverage of the second thermal insulation layer can still be guaranteed.

[0010] As an improvement of the utility model, the oxygen-isolating layer is extruded from a highly flame-retardant, high-crusting low-smoke halogen-free material, and the oxygen index is greater than 42%. Through the improvement, the crusting performance is better when heated and burned, and the structure of the cable is more stable. At the same time, the oxygen-isolating layer serves as the second flame-retardant layer, and the oxygen concentration in this area is originally extremely low, and the material with a high oxygen index can fully guarantee the flame-retardant effect.

[0011] As an improvement of the present invention, the isolation layer is made of high-temperature vitrified rubber material with a temperature resistance range of 600-1000°C. Through the improvement, in a high-temperature environment, the isolation layer can form a dense ceramic body structure that does not melt or drip, so as to achieve the effect of hindering the spread of flames. Similarly, the isolation layer also has the function of making the cable structure more stable.

[0012] As an improvement of the present invention, the first thermal insulation layer is also composed of multiple layers of mesh glass fiber tapes overlapped and wrapped, and the overlapping wrapping rate of each layer is not less than 25%. Through the improvement, the glass fiber has a better thermal insulation effect, and the mesh glass fiber has higher strength than the traditional glass fiber, so that the cable structure is more stable. In the absence of an armor layer to withstand mechanical stress, the cable structure can also be stable. The design of each layer overlapping and wrapping coverage rate of not less than 25% ensures the comprehensive coverage of the first thermal insulation layer, avoids the omission of the wrapping area, and also It can be ensured that when the cable is bent, the first thermal insulation layer can still ensure comprehensive coverage, wherein the overlapping wrapping overlap rate of the first thermal insulation layer is greater than that of the second thermal insulation layer, because the first thermal insulation layer needs to bear the main thermal insulation role, and the higher the overlapping wrapping overlap rate, the more complete the thermal insulation effect is. At the same time, the wrapping diameter of the first thermal insulation layer is greater than the wrapping diameter of the second thermal insulation layer. When the cable is bent, the relative displacement of the two overlapping layers of mesh glass fiber is greater. The higher the overlapping wrapping overlap rate, the more it can ensure that the two overlapping layers of mesh glass fiber are not separated, thereby ensuring comprehensive coverage of the first thermal insulation layer.

[0013] As an improvement of the utility model, the outer sheath is made of highly flame-retardant, high-crusting thermoplastic material with an oxygen index greater than 32%. Through the improvement, the crusting performance is better when burned by flames, the cable structure is more stable, and the effect of preventing the spread of flames is achieved.

[0014] As an improvement of the present utility model, the conductor is formed by twisting together a plurality of round monofilaments and a plurality of tile-shaped monofilaments. The plurality of round monofilaments are arranged in the inner layer of the conductor, and the plurality of tile-shaped monofilaments are arranged in the outer layer of the conductor and are connected end to end to form a circle to wrap the plurality of round monofilaments. Through the improvement, the structure of the outermost layer of the conductor can be made tighter and the gaps can be smaller, thereby reducing the phenomenon of electric field concentration on the surface of the conductor, which is conducive to passing the fire resistance test. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the cross-sectional structure of the utility model.

[0016] As shown in the figure: 1. Conductor, 1.1. Round monofilament, 1.2. Tile-shaped monofilament, 2. Second thermal insulation layer, 3. Oxygen insulation layer, 4. Isolation layer, 5. First thermal insulation layer, 6. Outer sheath, 7. Conductor shielding layer, 8. Insulation layer, 9. Insulation shielding layer, 10. Buffer layer, 11. Metal shielding layer. DETAILED DESCRIPTION

[0017] The embodiments of the present utility model are further described below in conjunction with the accompanying drawings.

[0018] like Figure 1As shown, a 10kV medium voltage fire-resistant single-core power cable comprises a body, the inner layer of the body is provided with only one conductor 1, the outer layer of the body is provided with a multifunctional isolation layer 4, the multifunctional isolation layer 4 comprises from the inside to the outside a second thermal insulation layer 2, an oxygen isolation layer 3, an isolation layer 4, a first thermal insulation layer 5 and an outer sheath 6, the second thermal insulation layer 2 and the first thermal insulation layer 5 are used for thermal insulation, the oxygen isolation layer 3 and the outer sheath 6 are used for flame retardancy, and the isolation layer 4 is used for high temperature isolation.

[0019] Between the conductor 1 and the multifunctional isolation layer 4, there are provided a conductor shielding layer 7, an insulating layer 8, an insulating shielding layer 9, a buffer layer 10, and a metal shielding layer 11 from inside to outside.

[0020] The conductor shielding layer 7 is made of a highly fluid, scorch-resistant, cross-linkable semi-conductive shielding material, and its average thickness is controlled at 0.6-0.7 mm.

[0021] The insulating layer 8 is made of peroxide cross-linked polyethylene material, and the thickness is determined according to the TICW8 standard.

[0022] The insulating shielding layer 9 is made of a non-peelable cross-linkable outer shielding material with higher smoothness, and its average thickness is controlled at 0.6-0.7 mm.

[0023] The buffer layer 10 is composed of a 1.5mm thick semi-conductive thermal insulation buffer tape and a 0.12mm thick semiconductor 1 reinforcement tape, and the overlap rate is not less than 20%; the semi-conductive thermal insulation buffer tape mainly plays an expansion buffering role when the insulation is heated, and the reinforcement tape can make the insulation more fixed in shape when heated in the molten state.

[0024] The metal shielding layer 11 is formed by overlapping and wrapping soft copper tapes with a thickness of 0.12-0.15 mm, and the wrapping overlap rate is not less than 15%. The metal shielding layer 11 mainly plays a role in conducting leakage current.

[0025] The second heat insulating layer 2 is formed by overlapping and wrapping multiple layers of mesh glass fiber tapes with a thickness of 0.25 mm, with an overlapping rate of each layer being not less than 15%, and the number of layers being at least two, so that the cable has higher strength and higher stability of the cable structure.

[0026] The oxygen-isolating layer 3 is extruded from a highly flame-retardant, high-crusting low-smoke halogen-free material, with an oxygen index greater than 42% and a thickness controlled at 2.5-4.5 mm according to the cable cross-sectional diameter. The crusting performance is better when heated and burned, and the cable structure is more stable.

[0027] The isolation layer 4 is made of high-temperature vitrified rubber material with a temperature resistance range of 600-1000°C. The thickness is controlled at 3-5mm according to the cable cross-sectional diameter. In a high-temperature environment, the isolation layer 4 can form a dense ceramic structure that does not melt or drip, so as to achieve the effect of hindering the spread of flames. Similarly, the isolation layer 4 also has the function of making the cable structure more stable.

[0028] The first heat insulating layer 5 is also formed by overlapping and wrapping multiple layers of mesh glass fiber tape with a thickness of 0.25 mm, with an overlapping rate of no less than 25% for each layer and 2-3 layers, so that the cable has higher strength and higher stability of the cable structure.

[0029] The outer sheath 6 is made of highly flame-retardant and highly encrusting thermoplastic material, with an oxygen index greater than 32% and a thickness determined according to the TICW8 standard. When subjected to flame combustion, the encrusting performance is better, the cable structure is more stable, and the effect of preventing the spread of flames is achieved.

[0030] Although the cable reduces the armor layer structure and the fireproof mud structure, the multiple reinforcement structure design of the multifunctional isolation layer 4 also makes the cable have higher usage strength, better stability, and good bending performance, which can be used for better transportation and laying.

[0031] The conductor 1 is formed by twisting together a plurality of round monofilaments 1.1 and a plurality of tile-shaped monofilaments 1.2. The plurality of round monofilaments 1.1 are arranged in the inner layer of the conductor 1, and the plurality of tile-shaped monofilaments 1.2 are arranged in the outer layer of the conductor 1 and connected end to end to form a circle to wrap the plurality of round monofilaments 1.1.

[0032] The design of 10kV medium voltage fire-resistant single-core power cable solves the problem that non-armored single-core medium voltage cables are difficult to pass the fire resistance test. At the same time, the cable is lighter and has better bending performance.

[0033] The above description is only for the best embodiment of the utility model, but it cannot be understood as a limitation of the claims. The utility model is not limited to the above embodiments, and its specific structure is allowed to be changed. All changes made within the protection scope of the independent claims of the utility model are within the protection scope of the utility model.

Claims

1. A 10kV medium voltage fire-resistant single-core power cable, comprising a body, characterized in that: The inner layer of the body is provided with only one conductor (1), the outer layer of the body is provided with a multifunctional isolation layer (4), the multifunctional isolation layer (4) comprising, from the inside to the outside, a second thermal insulation layer (2), an oxygen isolation layer (3), an isolation layer (4), a first thermal insulation layer (5) and an outer protective layer (6), the second thermal insulation layer (2) and the first thermal insulation layer (5) are used for thermal insulation, the oxygen isolation layer (3) and the outer protective layer (6) are used for flame retardancy, and the isolation layer (4) is used for high temperature isolation.

2. A 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The second heat insulating layer (2) is formed by overlapping and wrapping multiple layers of mesh glass fiber tapes, and the overlapping rate of each layer is not less than 15%.

3. A 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The oxygen barrier layer (3) is extruded from a highly flame-retardant, highly crusted, low-smoke, halogen-free material, and has an oxygen index greater than 42%.

4. A 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The isolation layer (4) is made of a high-temperature vitrified rubber material with a temperature resistance range of 600-1000°C.

5. The 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The first heat insulating layer (5) is also formed by overlapping and wrapping multiple layers of mesh glass fiber tapes, and the overlapping rate of each layer is not less than 25%.

6. A 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The outer protective layer (6) is made of highly flame-retardant and highly crusting thermoplastic material, and the oxygen index is greater than 32%.

7. The 10kV medium voltage fire-resistant single-core power cable according to claim 1, characterized in that: The conductor (1) is formed by twisting together a plurality of circular monofilaments (1.1) and a plurality of tile-shaped monofilaments (1.2); the plurality of circular monofilaments (1.1) are arranged in the inner layer of the conductor (1), and the plurality of tile-shaped monofilaments (1.2) are arranged in the outer layer of the conductor (1) and are connected end to end to form a circle to wrap the plurality of circular monofilaments (1.1).

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