A medium voltage fireproof cable for use in shafts or high-rise buildings

Abstract

The invention discloses a medium-voltage fireproof cable for use in a shaft or a high-rise building. The core body includes three wire cores, and the gaps between the three wire cores are filled with three steel wire ropes. Each wire core includes a conductor, and the outside of the conductor is wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer, and a copper tape shielding layer in sequence; the outer sheath is a heat-insulating tape layer, a heat-insulating fireproof layer, a steel wire armor layer, a fireproof layer, and an outer sheath in sequence from the inside to the outside. When in use, the wire core and the steel wire rope cooperate with each other to form a stable structure, which increases the load-bearing capacity of the entire cable, so that the cable is in a vertical state, and the internal and external load-bearing capacity is stable, thereby ensuring the normal operation of the cable.

Description

Technical Field

[0001] The invention mainly relates to the technical field of fireproof cables, and in particular to a medium-voltage fireproof cable used in shafts or high-rise buildings. Background Art

[0002] With the rapid development of my country's economy, there are more and more important engineering facilities such as high-rise buildings and mining. Due to the load's requirements for electricity, a medium-voltage power supply system is used. The safety performance of medium-voltage cables in the event of fire is required, requiring the cables to maintain normal power supply for a period of time in the event of a fire, so as to facilitate escape and rescue. Therefore, medium-voltage fire-resistant cables came into being. At the same time, medium-voltage cables are generally heavier in weight, so when they are laid vertically, requirements are put forward for the load-bearing capacity of the cables. Summary of the invention

[0003] In view of the above problems, the present invention provides a medium voltage fireproof cable for use in shafts or high-rise buildings. By strengthening the core structure and the outer sheath, the load-bearing capacity of the cable is greatly enhanced, and the fireproof performance is good.

[0004] The object of the present invention can be achieved by the following technical scheme: a medium-voltage fireproof cable for use in shafts or high-rise buildings, comprising a core body and an outer sheath arranged outside the core body, characterized in that the core body comprises three wire cores, the gaps between the three wire cores are filled with three steel wire ropes, each wire core comprises a conductor, and the outside of the conductor is sequentially wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer; the outer sheath is sequentially composed of a thermal insulation tape layer, a thermal insulation fireproof layer, a steel wire armor layer, a fireproof layer and an outer sheath from the inside to the outside.

[0005] Preferably, the three cores are arranged in a triangle, and the three steel ropes are also arranged in a triangle corresponding to the three cores. Each steel rope is embedded in the gap between two cores, and inorganic glass fiber ropes are filled between the three cores, the three steel ropes and the outer sheath.

[0006] Furthermore, a steel wire rope with a diameter of 4-6 mm is used, and a steel wire rope sheath is extruded outside the steel wire rope, so that the steel wire rope has a circular or triangular appearance, and the center distance of each steel wire rope is greater than the center distance of the wire core.

[0007] Furthermore, the steel wire armor layer is composed of steel wires closely arranged on the outer periphery of the cable core, the gap between the steel wires is minimal, and the total gap between the steel wires is not greater than the outer diameter of one steel wire. The steel wire here is galvanized steel wire, and the diameter of the single wire of the steel wire is 2-3.5mm.

[0008] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects:

[0009] 1. The improved scheme of the present invention comprises three wire cores, and the gaps between the three wire cores are filled with three steel wire ropes. The wire cores and the steel wire ropes cooperate with each other to form a stable structure, which increases the load-bearing capacity of the entire cable, so that the cable is in a vertical state, and the internal and external load-bearing capacity is stable, thereby ensuring the normal operation of the cable;

[0010] 2. In the technical solution of the present invention, each wire core includes a conductor, and the outside of the conductor is wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer in sequence; the outer sheath is a heat-insulating tape layer, a steel wire armor layer, a fireproof layer and an outer sheath from the inside to the outside. With this double fireproof structure, the flame temperature of the cable is not less than 750°C under the rated working voltage, and the fuse is disconnected within 90 minutes of the fire supply time;

[0011] 3. The cable core layout of the present invention is reasonable, which not only meets the fire resistance requirements of the cable, but also takes into account the material selection, structural dimensions, and electrical performance, while achieving the purpose of reducing costs;

[0012] 4. The cable of the present invention has good heat insulation and is environmentally friendly, non-toxic and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the present invention.

[0014] The following are marked in the figure:

[0015] 1 conductor, 2 conductor shielding layer, 3 insulation layer, 4 insulation shielding layer, 5 copper tape shielding layer, 6 steel wire rope, 7 steel wire rope sheath, 8 inorganic glass fiber rope, 9 thermal insulation tape layer, 10 thermal insulation fireproof layer, 11 steel wire armor layer, 12 fireproof layer, 13 outer sheath. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that those skilled in the art can more clearly understand how to practice the present invention. Although the present invention is described in conjunction with its preferred specific embodiments, these embodiments are only illustrative, rather than limiting the scope of the present invention.

[0017] like Figure 1 As shown, a medium-voltage fireproof cable for use in shafts or high-rise buildings comprises a core body and an outer sheath arranged outside the core body. The difference between the core body and the prior art is that the core body comprises three wire cores, the gaps between the three wire cores are filled with three steel wire ropes, each wire core comprises a conductor, and the outside of the conductor is sequentially wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer; the outer sheath is sequentially composed of a heat-insulating tape layer, a heat-insulating fireproof layer, a steel wire armor layer, a fireproof layer and an outer sheath from the inside to the outside.

[0018] Specifically, the three cores are arranged in a triangle, and the three steel wire ropes are also arranged in a triangle corresponding to the three cores. Each steel wire rope is embedded in the gap between the two cores, and inorganic glass fiber ropes are filled between the three cores, the three steel wire ropes and the outer sheath. Because of the double load-bearing structure design, the three steel wire ropes inside the cable core bear the load, and the steel wire armor outside the cable core bears the load, so that the cable is in a vertical state, and the internal and external load-bearing is stable, ensuring the normal operation of the cable.

[0019] In one embodiment, three steel ropes are filled in the gaps between the three cores. The three cores are arranged in a triangle. The three steel ropes are also arranged in a triangle and corresponding to the three cores. The corresponding arrangement here means that the three cores are arranged in a regular triangle, and the three steel ropes are arranged in an inverted triangle. The two are combined together to form a stable structure. At the same time, the steel rope is wrapped with a low-smoke halogen-free sheath material, so that the steel rope and the external sheath form a triangular shape, which can better resolve and withstand external force no matter where it comes from.

[0020] Furthermore, a steel wire rope with a diameter of 4.5mm is used. Here, the distance from the center of the steel wire rope to the center of the entire cable is greater than the center distance of the core, ensuring that the steel wire rope is more directly subjected to force when squeezed or loaded. At the same time, in order to ensure the relative position of the steel wire rope and the core, a number of connecting steel belts are provided between the outside of the steel wire rope and the core. These steel belts are connected in an alternating arrangement such as the first 10mm, the second 20mm, the third 10mm, the fourth 20mm... This way, there is a certain amount of room for movement, which is convenient, and there is a close connection, which ensures correspondence during transportation and use. At the same time, the spacing between adjacent steel belts is 8cm.

[0021] Furthermore, the outer surface of the wire core and the steel wire rope is coated with a heat-insulating tape layer, which is formed by wrapping a glass fiber tape to further fix the relative position of the wire core and the steel wire rope; then a heat-insulating and fire-proof layer is extruded outside the glass fiber tape, using a ceramic polyolefin material with a thickness of 1.5mm. The ceramic polyolefin material has excellent fire-proof properties. It can form a hard ceramic-like hard shell under the burning of flames. The hard shell does not melt or drip in a fire environment (650℃-3000℃), and has a very good heat-insulating and fire-proofing effect. The steel wire armor layer is composed of steel wires tightly arranged on the outer periphery of the cable core. The gap between the steel wires is the smallest, and the total gap between the steel wires is not greater than the outer diameter of one steel wire. The steel wires here are galvanized steel wires, which can ensure that once the outer layer is deformed when subjected to force, it can have an energy absorption effect to ensure that the internal wire core will not be broken. The outer layer of steel wire plays a role in further bearing external forces. At the same time, the steel wires here are galvanized steel wires, and the diameter of the single wire of the steel wire is 3mm.

[0022] In another embodiment, the core body includes three wire cores, the gaps between the three wire cores are filled with three steel ropes, each wire core includes a conductor, and the outside of the conductor is wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer in sequence; the outer sheath is, from the inside to the outside, an insulating tape layer, a steel wire armor layer, a fireproof layer and an outer sheath.

[0023] Furthermore, the three cores are arranged in a triangle, and the three steel wire ropes are also arranged in a triangle corresponding to the three cores. Each steel wire rope is embedded in the gap between the two cores, and inorganic glass fiber ropes are filled between the three cores, the three steel wire ropes and the outer sheath. A steel wire rope with a diameter of 5.5 mm is used, and the steel wire rope is extruded with a steel wire rope sheath, so that the steel wire rope has a circular outer profile, and the center distance of each steel wire rope is greater than the center distance of the core.

[0024] In actual use, it is found that since the steel wire rope is arranged in the gap between the two cores, it is easy to be further embedded in the gap when squeezed, so that the effect of the impact force is weakened. In order to improve the impact resistance and deformation resistance of the steel wire rope, a spring piece with a circular arc cross-section is arranged in the gap between adjacent cores, and the arc surface faces the steel wire rope. Once the steel wire rope is squeezed and slides toward the gap, the spring piece will exert a rebound force to ensure that the steel wire rope reduces sliding toward the gap, thereby improving the impact resistance of the steel wire rope. Such spring pieces are arranged every 20-30cm along the axial direction of the cable. Furthermore, such arc-shaped spring pieces are provided with a V-shaped support on the back of the working surface, that is, the opposite side of the arc surface, which further plays a role in enhancing the elastic force.

[0025] Specifically, the steel wire armor layer is composed of steel wires tightly arranged on the outer periphery of the cable core, with the smallest gap between the steel wires, and the total gap between the steel wires is no greater than the outer diameter of a steel wire. The steel wire armor layer is composed of two layers of steel wires in reverse armor, with the inner layer to the left and the outermost layer to the right, and then the upper and lower layers are staggered to form a mesh cover of the steel wire armor, which further plays a role in reinforcement. At the same time, the structure has an axial impact-resistant buffering effect. Here, the innermost steel wire layer uses a 2mm diameter steel wire, and the outer layer uses a 2.5mm diameter steel wire. The inner layer of steel wire is provided with raised steel balls with a diameter of 2-2.5mm, which plays a role in strengthening protection. Here, the spacing between adjacent steel balls is 1-1.5cm. Furthermore, in order to ensure the close fit and firmness of the two layers of steel wire, the surfaces of the inner and outer layers of steel wire are roughened to increase the friction and bonding between each other. The thickness of the fireproof layer is 1.8-3mm; the outer sheath is extruded on the fireproof layer by extrusion, with a thickness of 2.5-4.0mm, and the material is low-smoke halogen-free sheath material.

[0026] In a specific embodiment, the core body includes three wire cores, the gaps between the three wire cores are filled with three steel ropes, each wire core includes a conductor, and the outside of the conductor is wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer in sequence; the outer sheath is, from the inside to the outside, an insulating tape layer, a steel wire armor layer, a fireproof layer and an outer sheath.

[0027] First, the conductors are twisted. The circular compact copper conductor is used, and the conductor structure is dense. Under the same conductor cross-sectional area, the outer diameter of the conductor is reduced by about 10% after compaction, thereby reducing the outer diameter of the product and facilitating installation and laying. Then three layers are co-extruded. The conductor shielding layer, the insulating layer, and the insulating shielding layer are produced by three-layer co-extrusion. The conductor shielding material, the cross-linked polyethylene insulating material, and the insulating shielding material are coated on the compacted conductor at one time. The extrusion production process is adopted, so that the three layers of materials are closely combined together, and at the same time, the secondary pollution of the insulating material is avoided, and the process quality of the product is guaranteed. Then, a layer of 0.1-0.12mm copper tape is overlapped and wrapped on each insulating core to shield the electric field interference and balance the electric field. In addition to ensuring that the insulating shield (semi-conductive shield) is at the ground potential (neutral point), the ground fault current can also pass through. When cabling, the cable core is twisted to the right, and the three cores are located in the middle of the cable core, forming a triangular structure. The three steel wire ropes are in the gap between the three cores, forming a symmetrical structure of three large and three small. The steel wire rope is 5mm, and the steel wire rope is extruded with low-smoke halogen-free sheath material with a thickness of 1.5mm. The steel wire rope plays a load-bearing role during hoisting. Inorganic glass fiber rope is filled in the gap between the cable core and the steel wire rope to make the cable round. Two layers of glass fiber tape are wrapped around the cable core, with a thickness of 0.2mm. The wrapping tape is used to make the cable core tight and round, and the glass fiber tape is environmentally friendly and non-toxic, with high temperature resistance and fire resistance, and excellent thermal insulation performance.

[0028] The heat insulation and fireproof layer is extruded outside the glass fiber tape, using ceramic polyolefin material. According to different specifications, the thickness is 1.0mm-2.5mm. Ceramic polyolefin material has excellent fireproof properties. It can form a hard ceramic shell under the burning of flames. The shell does not melt or drip in a fire environment (650℃-3000℃), and has very good heat insulation and fireproof effects.

[0029] The steel wires of the steel wire armor layer are galvanized steel wires. According to different specifications, the diameter of the steel wire single wire is 2.0mm, 2.5mm, 3.15mm; the number of wires is 50-80. The armored steel wire and the wire rope together play the role of cable load-bearing. At the same time, the armored steel wire is impact-resistant and forms a fire barrier to prevent the flame from spreading into the cable, effectively protecting the cable core from external impact damage.

[0030] The thickness of the fireproof layer is 2.0mm. The material is a mixture of aluminum hydroxide hydrate (or magnesium hydroxide hydrate) and sodium silicate in a certain proportion. Since the mixture contains a large amount of aluminum hydroxide hydrate (or magnesium hydroxide hydrate), it decomposes at high temperature to produce a large amount of water to form water mist, which plays a role in cooling and fire prevention. While extruding the fireproof layer, two layers of high flame retardant tapes are overlapped and wrapped at the die outlet to prevent the fireproof mud from dripping and overflowing. After high temperature, a hard shell can be formed with good thermal insulation and a thermal conductivity of 0.09W / Mk. In particular, the interior after ablation is uniformly honeycombed, which has better fire resistance and thermal insulation.

[0031] The outer sheath is extruded on the fireproof layer with a thickness of 2.5-4.0mm. The material is low-smoke halogen-free sheath material, and the outer sheath plays a protective role.

[0032] In summary, the advantages of the present invention are as follows:

[0033] 1. Excellent fireproof performance: double fireproof structure, the cable is under rated working voltage, the flame temperature is not less than 750℃, and the fuse is not broken within 90 minutes of fire supply time.

[0034] 2. Excellent self-supporting performance: Double load-bearing structure design, three steel ropes bear the load inside the cable core, and the steel wire armor bears the load outside the cable core, so that the cable is in a vertical state, with stable internal and external load-bearing, ensuring the normal operation of the cable.

[0035] 3. Economical: Reasonable design of structure and selection of suitable fire-resistant and fireproof materials can not only meet the fire resistance needs of cables, but also take into account material selection, structural dimensions, and electrical performance, while achieving the goal of reducing costs.

[0036] 4. Environmentally friendly: no heavy metals, non-toxic, odorless, no impact on human body and environment.

[0037] 5. Good thermal insulation, thermal conductivity 0.09W / Mk, especially the interior after ablation is uniform honeycomb, with better fire resistance and thermal insulation.

[0038] It should be noted that the fully described invention may also have a variety of variations and modifications, and is not limited to the specific embodiments of the above embodiments. The above embodiments are merely illustrative of the invention, not limiting thereof. In short, the scope of protection of the invention should include those variations or substitutions and modifications that are obvious to a person of ordinary skill in the art, and shall be subject to the appended claims.

Claims

1. A medium voltage fireproof cable for use in a shaft or a high-rise building, comprising a core and an outer sheath arranged outside the core, characterized in that: The core body includes three wire cores, and the gaps between the three wire cores are filled with three steel wire ropes. Each wire core includes a conductor, and the outside of the conductor is wrapped with a conductor shielding layer, an insulating layer, an insulating shielding layer and a copper tape shielding layer in sequence; the outer sheath is a heat insulation tape layer, a heat insulation fireproof layer, a steel wire armor layer, a fireproof layer and an outer sheath from the inside to the outside; the three wire cores are arranged in a triangle, and the three steel wire ropes are also arranged in a triangle and arranged corresponding to the three wire cores. Each steel wire rope is embedded in the gap between two wire cores, and an inorganic glass fiber rope is filled between the three wire cores, the three steel wire ropes and the outer sheath; A spring piece with an arc-shaped cross section is arranged at the gap between adjacent cores, with the arc-shaped surface facing the wire rope. The spring piece is arranged every 20-30 cm along the cable axis, and a V-shaped support is arranged on the reverse side of the arc-shaped surface of the spring piece; The steel wire armor layer is formed by 2 layers of steel wires in reverse armoring, with the inner layer on the left and the outermost layer on the right. The upper and lower layers are staggered to form a mesh cover of the steel wire armor; the inner steel wire layer adopts 2mm diameter steel wire, and the outer layer adopts 2.5mm diameter steel wire. The inner steel wire is provided with raised steel wool balls with a diameter of 2-2.5mm. The spacing between adjacent steel wool balls is 1-1.5cm, and the surfaces of the inner and outer steel wires are roughened.

2. A medium voltage fireproof cable for use in a shaft or a high-rise building according to claim 1, characterized in that: A steel wire rope with a diameter of 4-6 mm is used, and a steel wire rope sheath is extruded outside the steel wire rope, so that the steel wire rope is circular or triangular in shape, and the center distance of each steel wire rope is greater than the center distance of the wire core.

3. A medium voltage fireproof cable for use in a shaft or a high-rise building according to claim 1, characterized in that: The thermal insulation tape layer is formed by wrapping glass fiber tape to fix the relative position of the wire core and the steel wire rope; the thermal insulation and fireproof layer is formed by extruding ceramic polyolefin material.

4. A medium voltage fireproof cable for use in a shaft or a high-rise building according to claim 1, characterized in that: The gap between the inner steel wires is larger than the gap between the outer steel wires. The outer steel wires are provided with braided fixing knots. The steel wires here are galvanized steel wires.

5. A medium voltage fireproof cable for use in a shaft or a high-rise building according to claim 1, characterized in that: The thickness of the fireproof layer is 1.8-3mm; the outer sheath is extruded on the fireproof layer by extrusion, with a thickness of 2.5-4.0mm, and the material is low-smoke halogen-free sheath material.

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