CN214336375U - Concentric conductor flexible fireproof cable - Google Patents
Concentric conductor flexible fireproof cable Download PDFInfo
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- CN214336375U CN214336375U CN202120218225.XU CN202120218225U CN214336375U CN 214336375 U CN214336375 U CN 214336375U CN 202120218225 U CN202120218225 U CN 202120218225U CN 214336375 U CN214336375 U CN 214336375U
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Abstract
A concentric conductor flexible fireproof cable is structurally characterized in that: the conductor is wrapped with an insulating layer to form a wire core; the plurality of wire cores and the filling ropes are twisted to form a cable core; the cable core is sequentially wrapped with a fire-resistant protective layer, a concentric conductor and an outer sheath from inside to outside; the stranding pitch diameter ratio of the wire core and the filling rope is not more than 35; the conductor is a solid round copper conductor or is formed by stranding a plurality of bare copper monofilaments; the insulating layer is extruded with ceramic silicon rubber; the fire-resistant protective layer is formed by wrapping 2 layers of ceramic composite belts and 1 layer of low-smoke halogen-free flame-retardant non-woven fabric, and the overlapping wrapping rate is not less than 25%; the concentric conductor is composed of a corrugated copper pipe wrapped outside the fireproof protective layer, and the wall thickness of the corrugated copper pipe is 0.4-0.7 mm; the outer sheath is formed by extruded halogen-free low-smoke flame-retardant polyolefin or cross-linked polyethylene; the thickness of the outer sheath is not less than 1.8 mm. The cable adopting the structure is beneficial to solving a plurality of problems in the prior art.
Description
Technical Field
The utility model belongs to the technical field of the cable, specifically a flexible fireproof cable of concentric type conductor.
Background
Technical difficulties and principle analysis in the prior art:
the power distribution occasions such as power stations, power plants, high-rise buildings, tunnels, subways and computer rooms attach importance to the type selection of cables day by day, and the use of common low-voltage power cables can bring many insufficient problems to engineering design, power transmission and distribution network operation, fire safety and the like, and the following defects are mainly existed:
1. the cable has poor anti-interference performance, and when the current transmitted by the cable contains higher harmonic components, the cable can generate electromagnetic interference on electronic equipment around the cable; on the contrary, the external electromagnetic interference can be coupled to the core wire of the cable, and the electromagnetic interference is generated on various electric appliances connected with the cable;
2. the phase-zero short circuit impedance is large, so that the single-phase short circuit current value of the line is reduced, and the sensitivity of the head end protection device in single-phase short circuit is influenced. Of particular note are: in a zero connection system with a power supply neutral point directly grounded, when one phase of insulation of a cable is broken down and one phase is grounded, the value of a grounding short circuit current is very small, so that an overcurrent protection device at the head end of a line cannot effectively act, and the electrical equipment and personal safety of the whole system are endangered;
3. the cables laid in high-rise buildings are difficult to avoid the damage or the breakdown of the insulating layer due to the overvoltage generated under the electromagnetic effect of strong lightning current because of no shielding layer.
4. Once a common cable is burnt, the power supply cannot be guaranteed when a fire disaster actually occurs, and people evacuation, channel illumination, a fire prevention alarm device, automatic fire fighting equipment and other emergency equipment all require that the cable can be normally powered on within a specified time when the fire disaster occurs.
SUMMERY OF THE UTILITY MODEL
In order to solve the above-mentioned problem that exists among the prior art, the utility model provides a novel flexible fireproof cable of concentric type conductor, its structure is:
the conductor is wrapped with an insulating layer to form a wire core; the plurality of wire cores and the filling ropes are twisted to form a cable core; the cable core is sequentially wrapped with a fire-resistant protective layer, a concentric conductor and an outer sheath from inside to outside;
the stranding pitch diameter ratio of the wire core and the filling rope is not more than 35;
in the conductor:
the radial cross-sectional area of the conductor is not more than 6mm2Then the conductor is a solid round copper conductor;
the radial cross-sectional area of the conductor is not less than 10mm2The conductor is formed by twisting a plurality of bare copper monofilaments, and the twist pitch diameter ratio ranges from 10 to 20;
the diameter of the bare copper monofilament is 1.36-3.85 mm, and the diameter of the bare copper monofilament is selected according to the radial sectional area of the conductor as required.
The insulating layer is formed by extruding ceramic silicon rubber;
the fire-resistant protective layer is formed by wrapping 2 layers of ceramic composite belts and 1 layer of low-smoke halogen-free flame-retardant non-woven fabric; the wrapping structure is: wrapping 1 layer of the ceramic composite belt, wrapping the 2 nd layer of the ceramic composite belt, and wrapping 1 layer of the low-smoke halogen-free flame-retardant non-woven fabric. The overlapping lapping and covering rate of the three layers of composite tapes is not less than 25%.
The concentric conductor is composed of a corrugated copper pipe wrapped outside the fireproof protective layer, and the wall thickness of the corrugated copper pipe is 0.4-0.7 mm;
the outer sheath is formed by extruded halogen-free low-smoke flame-retardant polyolefin or cross-linked polyethylene; the thickness of the outer sheath is not less than 1.8 mm.
The outer diameter range of the concentric conductor flexible fireproof cable is as follows: 15 mm-50 mm.
The filling rope is a glass fiber filling rope.
The insulating layer is made of extruded ceramic silicon rubber insulating materials; the thickness of the insulating layer is specified by JB/T13106-2017 Table 3, and the thinnest point is not smaller than 90-0.1 mm of the nominal thickness.
Preferably, the fire-resistant protective layer is formed by lapping 2 layers of ceramic composite belts with nominal thickness of 0.3mm and 1 layer of low-smoke halogen-free flame-retardant non-woven fabrics with nominal thickness of 0.2mm, and the lapping rate of the lapping is not less than 25%;
the concentric conductor is a copper strip with the nominal thickness of 0.4mm to 0.7mm, the copper strip is welded into a copper tube through argon arc welding, the copper tube is rolled into a corrugated copper tube through a rolling machine, and the thickness and the width of the copper strip are selected through calculation of the outer diameter of a cable core and the nominal sectional area of the concentric conductor;
selecting the thickness of the copper strip:
if the diameter of the cable core is less than or equal to 10, a copper strip with the thickness of 0.4mm is used, the embossing depth is 0.7-1.2mm, and the embossing pitch is 4-6 mm;
when the diameter of the cable core is more than 10 and less than or equal to 20, a copper strip with the thickness of 0.5mm is used, the embossing depth is 1.2-1.7mm, and the embossing pitch is 5-7 mm;
when the diameter of the cable core is more than 20 and less than or equal to 30, a copper strip with the thickness of 0.6mm is used, the embossing depth is 1.7-2.2mm, and the embossing pitch is 7-9 mm;
if the diameter of the cable core is more than 30, a copper strip with the thickness of 0.7mm is used, the embossing depth is 1.7-2.2mm, and the embossing pitch is 9-12 mm.
Selecting the width of the copper strip: the outer diameter of the fire-resistant protective layer is +0.1mm-0.2mm (a gap is reserved between the copper sheath and the cable core) +2 multiplied by the embossing depth +2 multiplied by the thickness of the copper strip.
If the thickness of the copper strip is multiplied by the width of the copper strip and is larger than the nominal sectional area of the concentric conductor, the copper strip is determined to be selected; otherwise, the thickness of the copper strip is increased by one gear until the requirement is met.
The outer sheath is composed of extruded halogen-free low-smoke flame-retardant polyolefin or cross-linked polyethylene, and the thickness of the outer sheath is not less than 1.8mm according to a calculation method of the thickness of the outer sheath of the concentric conductor in GB/T12706.1.
The filling material is formed by stranding a plurality of single-stranded flame-retardant high-temperature filling ropes (such as glass fiber filling ropes).
The cable adopting the structure is beneficial to solving a plurality of problems in the prior art.
Drawings
Fig. 1 is a schematic view of a radial cross-sectional structure of the cable of this example.
In the figure: 1. a conductor; 2. an insulating layer; 3. filling a rope; 4. a refractory protective layer; 5. a concentric conductor; 6. An outer sheath.
Fig. 2 is a schematic diagram illustrating a principle of zero-crossing for power equipment protection in the prior art.
In the figure: short-circuit fault current when Id-phase line touches the shell; rc-repetitive ground resistance; ro-working ground resistance; rD-a fuse.
Detailed Description
The technical solution is further explained with reference to the following drawings and specific embodiments:
referring to fig. 1, the structure of the novel concentric conductor flexible fireproof cable of the present embodiment is: the conductor 1 is wrapped with the insulating layer 2 to form a wire core; a plurality of wire cores (4 in the example) and the filling ropes 3 are twisted to form a cable core; the stranding pitch diameter ratio of the wire core and the filling rope is not more than 35; the cable core is sequentially wrapped with a fire-resistant protective layer 4, a concentric conductor 5 and an outer sheath 6 from inside to outside;
the diameter scope that this cable structure was suitable for: 15 mm-50 mm.
In the embodiment, the cable core is formed by twisting 4 wire cores and a glass fiber filling rope 3; the pitch-diameter ratio of the cable core twisting is not more than 35.
the insulating layer 2 is formed by extruded ceramic silicon rubber, the insulating thickness refers to the surface 3 in JB/T13106-containing 2017, and the minimum point is 90-0.1 mm of the nominal thickness;
the fire-resistant protective layer 4 consists of 2 layers of ceramic composite belts with nominal thickness of 0.3mm and 1 layer of low-smoke halogen-free flame-retardant non-woven fabrics with nominal thickness of 0.2mm, and the overlapping lapping rate is not less than 25%;
the concentric conductor 5 is a copper strip with the nominal thickness of 0.4mm to 0.7mm, is welded into a copper tube through argon arc welding, and is rolled into a corrugated copper tube through a rolling machine, and the thickness and the width of the copper strip are selected through calculation of the outer diameter of a cable core and the nominal sectional area of the concentric conductor;
the outer sheath 6 is composed of extruded halogen-free low-smoke flame-retardant polyolefin or cross-linked polyethylene, and the thickness of the outer sheath is not less than 1.8mm according to a calculation method of the thickness of the outer sheath of a concentric conductor in GB/T12706.1.
The filling rope is formed by twisting a plurality of single-stranded flame-retardant high-temperature filling ropes.
First, description of technical principle of the present cable
1. Design principle of concentric conductor
Department of energy SDJ 8-79: the technical specification of grounding design of power equipment stipulates: in a low-voltage power network with a neutral point directly grounded, the shell of the power equipment is preferably protected by low-voltage zero connection, namely zero connection, and the zero line is specified to be grounded at a power supply. The neutral line is a neutral line connected to a neutral point to which a transformer or a generator is directly grounded, or a grounded neutral line in a dc circuit. The connection between the shell of the power equipment and the zero line is zero connection. The principle of zero connection for protection is shown in fig. 2, when a phase line collision shell fault occurs in the electrical equipment, the value of the short-circuit current Id is large, so that the fuse RD (or an automatic switch) rapidly acts to cut off the power supply.
2. Cross-sectional requirements of concentric conductors
SDJ 26-89 stipulate in Power plant, substation Cable selection and laying design rules: "the effective section of the metal shield of the power cable is suitable for meeting the principle that the temperature of the shield layer is not more than 150 ℃ (polyvinyl chloride outer sheath) or 140 ℃ (polyethylene outer sheath) under various possible operation modes (such as two-phase grounding short circuit of different places in a system with neutral points not directly grounded). SD 289-88 technical Specification for import 1-35 kV rubber and plastic Cable also stipulates: the effective section of the metal shielding layer is required to be capable of generating ground fault in the system (the neutral point grounding system is single-phase grounding fault, the neutral point is not grounding and is two-phase simultaneous grounding fault at different places), and when fault current passes through the metal shielding, the temperature of the shielding layer does not exceed the maximum collection heat-resisting temperature at the inner side of the shielding layer). In the metal shield, the short-circuit current and the conductive section are determined according to the short-circuit capacity of the power grid system and the grounding mode of the system. If the system neutral is directly grounded, the resulting short circuit current in the metallic shield will be the same as that of the cable conductive core, or half of the conductive core.
3. Mechanism of fire prevention
The causes of a fire or burning of a cable can be generally categorized into two parties. Firstly, the cable body is natural due to the overload or short circuit of the cable; and cable burning caused by external fire source. High molecular compounds composed of C, H elements are exposed to high-temperature flame under the aerobic condition, and the compounds are in an overheated state, release combustible gas and generate smoke and harmful gas. The concentric conductor flexible fireproof cable adopts ceramic silicon rubber as insulation, and the material has higher overload resistance and can not be decomposed by heating in a flame combustion state but be converted into an inorganic shell; the filling material and the protective layer material are both made of special materials, so that smoke and halogen gas cannot be emitted; the concentric conductor, due to its high melting point (1083 ℃) and overall tightness, acts as a flame barrier during combustion, preventing the flame from burning into the cable.
Second, description of technical effects of the present Cable
1. The stranded bare copper conductor improves the conductivity of the conductor.
2. The ceramic silicon rubber is insulated, can not be decomposed by heat in a flame combustion state, but is converted into an inorganic shell, and has excellent flame-retardant, fireproof, waterproof and anti-seismic functions.
3. When the power is transmitted, no interference is generated to surrounding electrical equipment; the influence of external electromagnetic interference on the electrical equipment connected to the cable is also eliminated.
4. Breakdown or damage caused by strong lightning magnetic effect voltage can be avoided, and the lightning protection effect and reliability of the high-rise building are improved.
5. The sensitivity of the overcurrent protection device at the head end of the line can be improved, so that the cable and the electrical equipment connected with the cable are effectively protected.
6. Has lower and uniform positive (reverse) sequence and zero sequence impedance, and is beneficial to improving the copper electric quality.
7. The earth fault caused by one-phase insulation breakdown can be eliminated as soon as possible.
8. The concentric conductors may act as a flame barrier to prevent flame from burning into the cable.
9. The concentric conductor can be used as a neutral wire and a grounding wire, so that the outer diameter of the cable can be greatly reduced in design, the weight of the cable is reduced, the material consumption is reduced, and the concentric conductor has excellent economy; and because the whole external diameter of the cable is reduced, the cable is more convenient to lay, and the cable can be installed and used in a narrow space.
10. The whole cable has good flame retardant and fire resistant performance, the finished cable meets the fire resistant test standard of GB/T19216.21, the flame temperature is 950 ℃, the rated voltage is applied, and the insulation is not broken down after the duration of 180 min; the fire-resistant test requirements of C (pure fire supply), W (fire supply and water spraying) and Z (fire supply and mechanical vibration) in the BS 6387 standard are met, and the test requirements that the test is carried out according to BS 8491 regulations and the circuit is kept complete are met; meets the related requirements of B1 grade in GB/T31247 cable and optical cable burning performance grading.
Besides the special properties, the concentric conductor flexible fireproof cable also meets the electrical properties (such as conductor resistance, voltage test, 4h voltage test, insulation resistance test and working capacitance) of the cable, the mechanical properties (such as insulation and sheath mechanical properties, insulation heat extension and the like), the halogen-free (gas evolution test during combustion, fluorine content test) and the non-toxic (insulation and sheath toxicity index) properties.
The cable test results are as follows:
Claims (5)
1. the utility model provides a flexible fireproof cable of concentric type conductor, characterized by structure is:
the conductor is wrapped with an insulating layer to form a wire core; the plurality of wire cores and the filling ropes are twisted to form a cable core; the cable core is sequentially wrapped with a fire-resistant protective layer, a concentric conductor and an outer sheath from inside to outside;
the stranding pitch diameter ratio of the wire core and the filling rope is not more than 35;
in the conductor:
the radial cross-sectional area of the conductor is not more than 6mm2Then the conductor is a solid round copper conductor;
the radial cross-sectional area of the conductor is not less than 10mm2The conductor is formed by twisting a plurality of bare copper monofilaments, the twist pitch diameter ratio range is 10-20, and the outer diameter range of the bare copper monofilaments is 1.36-3.85 mm;
the insulating layer is formed by extruding ceramic silicon rubber;
the fire-resistant protective layer is formed by wrapping 2 layers of ceramic composite belts and 1 layer of low-smoke halogen-free flame-retardant non-woven fabric, and the overlapping wrapping rate is not less than 25%;
the concentric conductor is composed of a corrugated copper pipe wrapped outside the fireproof protective layer, and the wall thickness of the corrugated copper pipe is 0.4-0.7 mm;
the outer sheath is formed by extruded halogen-free low-smoke flame-retardant polyolefin or cross-linked polyethylene; the thickness of the outer sheath is not less than 1.8 mm.
2. The concentric conductor flexible fireproof cable of claim 1, wherein the concentric conductor flexible fireproof cable has an outer diameter ranging from: 15 mm-50 mm.
3. The concentric conductor flexible fire-resistant cable of claim 1, wherein said filler cord is a glass fiber filler cord.
4. The concentric conductor flexible fireproof cable of claim 1, wherein the ceramic composite tape has a nominal thickness of 0.3 mm; the thickness of the low-smoke halogen-free flame-retardant non-woven fabric is 0.2 mm.
5. The concentric conductor flexible fireproof cable according to claim 1, wherein the wrapping structure of the fire-resistant protective layer is:
the method comprises the steps of firstly wrapping 1 layer of ceramic composite belt, then wrapping the 2 nd layer of ceramic composite belt, and finally wrapping 1 layer of low-smoke halogen-free flame-retardant non-woven fabric, wherein the overlapping wrapping and covering rate of the two layers is not less than 25%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120218225.XU CN214336375U (en) | 2021-01-27 | 2021-01-27 | Concentric conductor flexible fireproof cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120218225.XU CN214336375U (en) | 2021-01-27 | 2021-01-27 | Concentric conductor flexible fireproof cable |
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| Publication Number | Publication Date |
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| CN214336375U true CN214336375U (en) | 2021-10-01 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202120218225.XU Active CN214336375U (en) | 2021-01-27 | 2021-01-27 | Concentric conductor flexible fireproof cable |
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| CN (1) | CN214336375U (en) |
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2021
- 2021-01-27 CN CN202120218225.XU patent/CN214336375U/en active Active
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