Flame-retardant fireproof medium-voltage power cable
By employing a three-metal shielded insulated core stranded structure and a multi-layer fireproof design in medium-voltage power cables, the problems of slow heat dissipation, easy deformation, and heavy weight of existing medium-voltage fire-resistant power cables are solved, achieving better flame retardancy and fire resistance, and ensuring that the cables are not easily damaged in the event of a fire.
Patent Information
- Application Number
- CN202422809666.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2034-11-19
AI Technical Summary
Existing medium-voltage fire-resistant power cables have shortcomings in terms of flame retardancy and fire resistance. Insufficient contact between the mineral rope and the metal shielded insulated core leads to slow heat dissipation. The mineral fireproof mud structure is prone to deformation and cracking, causing temperature to be transferred to the cable core too early. The cables have a large outer diameter, are heavy, and are difficult to install.
It adopts a three-metal shielded insulated wire core stranded structure, combined with an inner and outer multi-layer fireproof design, including a flame-retardant oxygen barrier layer, an inner cooling fireproof layer and an outer cooling fireproof layer. Halogen-free low-smoke flame-retardant materials and fiberglass tape are used to form a cross-connected structure to enhance fire resistance. Non-woven fabric is added to the outer protective layer to stabilize the precipitation of mineral fireproof mud.
It improves the flame retardancy and fire resistance of the cable, reduces the cable's outer diameter and weight, maintains the cable's flexibility and installation flexibility, improves the cable's fire resistance and insulation performance, and prevents temperature from being transferred to the cable core too early.
Smart Images
Figure CN223728505U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to power cable, concretely relates to a kind of fire-retardant fire-resistant medium voltage power cable. BACKGROUND
[0002] Medium voltage power cable is widely used, and bears the transmission of external power lines required by engineering projects. It occupies an important position in the power system. Once a fire accident occurs in the power line, it will affect the normal operation of the entire project and cause significant economic losses. Therefore, the fire resistance requirements for reliable operation of medium voltage cable are continuously increasing.
[0003] However, the current medium voltage fire-resistant power cable has the following deficiencies:
[0004] 1) The existing medium voltage fire-resistant power cable is generally filled with mineral substances. Mineral substances are high-flame-retardant mineral ropes. As we all know, the fire resistance principle of medium voltage fire-resistant cable is to ensure that the temperature of external combustion transmitted to the insulation layer during combustion is not high enough to cause deformation and failure of the insulation layer while still maintaining its insulation performance. Although mineral ropes have good flame retardant and heat insulation properties, they cannot fully contact the metal shielded insulated core, resulting in poor heat transfer from external combustion to the metal shielded insulated core through mineral ropes, i.e., slow heat dissipation inside the cable, which can cause local overheating inside the cable and damage the insulation layer. Due to the large gap on the side of the metal shielded insulated core of the medium voltage cable, a large amount of mineral rope is used for filling. In addition, mineral ropes are prone to moisture absorption and corrosion of the metal shield.
[0005] 2) The existing medium voltage fire-resistant power cable uses mineral fireproof mud as the cable fireproof cooling structure outside the cable core. After a period of time, the mineral fireproof mud structure hardens and becomes fixed. The cable has poor bending performance. Once a fire occurs after the cable is used, the temperature outside the cable is transmitted through the mineral fireproof mud and can release moisture to have good cooling effect. As the combustion progresses, the mineral fireproof mud is sintered into a hard shell. This hard shell structure has good fire blocking, fireproofing and oxygen isolation effects, which can effectively slow down the transmission of external heat to the cable core. However, due to the circular structure of the mineral fireproof mud structure located outside the cable core, the cable is prone to cracks when it is bent and subjected to a large tensile force on the outside of the bend. If a fire occurs in the bent section of the cable, the temperature will be transmitted to the inside of the cable core through the cracks, causing local overheating and premature loss of insulation performance, and ultimately leading to the failure of the fire resistance characteristics.
[0006] 3) The mineral fireproof mud structure of the existing medium voltage fire-resistant power cable is soft and deformed during production, which can cause large eccentricity, uneven thickness, unstable fire resistance characteristics, large cable outer diameter, heavy cable weight, difficult product laying, and large installation space occupation.
[0007] 4) because the outer diameter of the medium-voltage fire-resistant power cable is large, when burning, the mineral fireproofing mud part of the cable away from the fire source does not burn sufficiently, cracks occur at the part where the temperature difference is large during the burning of the mineral fireproofing mud, the external burning temperature is prematurely transmitted to the inside of the cable core through the cracks, the local insulation of the cable is overheated and loses its insulation performance prematurely, and finally the fire-resistant property fails. SUMMARY
[0008] In view of the problems existing in the prior art medium-voltage fire-resistant power cable, the purpose of the present application is to provide a fire-resistant medium-voltage power cable which has good fire resistance and flame resistance and can effectively overcome the problems existing in the prior art.
[0009] To achieve the above-mentioned purpose, the present application adopts a fire-resistant medium-voltage power cable, which comprises a cable core, a comprehensive fireproofing layer, a protective layer and an outer protective layer from inside to outside.
[0010] The cable core comprises three metal shielded insulated wire cores which are twisted with each other.
[0011] Each metal shielded insulated wire core comprises a conductor, and the conductor is surrounded by a conductor shielding layer, a plastic insulation layer, an insulation shielding layer and a metal shielding layer from inside to outside.
[0012] The comprehensive fireproofing layer comprises an inner heat insulation layer, an oxygen-blocking flame-retardant layer, an inner temperature-reducing fireproofing layer, a middle heat insulation layer, an outer temperature-reducing fireproofing layer and an outer heat insulation layer from inside to outside.
[0013] In the above-mentioned fire-resistant medium-voltage power cable, the oxygen-blocking flame-retardant layer is provided with a plurality of sawtooth protrusions which are uniformly distributed on the outer surface.
[0014] In the above-mentioned fire-resistant medium-voltage power cable, the conductor is a second tightly compressed round twisted copper conductor.
[0015] In the above-mentioned fire-resistant medium-voltage power cable, the plastic insulation layer is formed by extruding plastic insulation material, and the plastic insulation material can be cross-linked polyethylene or polypropylene.
[0016] In the above-mentioned fire-resistant medium-voltage power cable, the inner heat insulation layer, the middle heat insulation layer and the outer heat insulation layer are formed by overlapping and wrapping glass fiber belts.
[0017] In the above-mentioned fire-resistant medium-voltage power cable, the oxygen-blocking flame-retardant layer is formed by extruding halogen-free low-smoke flame-retardant polyolefin oxygen-blocking material.
[0018] In the above-mentioned fire-resistant medium-voltage power cable, the inner temperature-reducing fireproofing layer and the outer temperature-reducing fireproofing layer are formed by extruding mineral fireproofing mud.
[0019] In the fire-retardant fire-resistant medium-voltage power cable, the outer sheath can be a halogen-free low-smoke fire-retardant polyolefin sheath extruded or a composite structure of a metal reinforcing layer and a plastic sheath extruded outside the metal reinforcing layer.
[0020] In the fire-retardant fire-resistant medium-voltage power cable, the inner surfaces of the sections of the inner thermal insulation layer are all triangular, and each side of the triangle is tangent to the metal shielded and insulated wire core.
[0021] The fire-retardant fire-resistant medium-voltage power cable has good fire resistance and fire-retardant performance, and can effectively overcome the problems in the prior art.
[0022] The fire-retardant fire-resistant medium-voltage power cable has good fire resistance and fire-retardant performance, and can effectively overcome the problems in the prior art.
[0023] The fire-retardant fire-resistant medium-voltage power cable has a small overall outer diameter and light weight. BRIEF DESCRIPTION OF DRAWINGS
[0024] The utility model will be further described below in combination with the drawings and specific embodiments.
[0025] Figure 1 The utility model provides an example of the cross section of the fire-retardant fire-resistant medium-voltage power cable. DETAILED DESCRIPTION
[0026] In order to make the technical means, creative features, purposes and effects of the utility model easy to understand, the utility model will be further described below in combination with specific drawings.
[0027] Referring to Figure 1 The figure shows an example of the structure of the fire-retardant fire-resistant medium-voltage power cable.
[0028] As shown in the figure, the fire-retardant fire-resistant medium-voltage power cable in the example comprises a cable core 200, a comprehensive fireproof layer 300, a protective layer 400 and an outer sheath 500 from inside to outside.
[0029] The cable core 200 in the example mainly comprises three metal shielded and insulated wire cores 100.
[0030] The three metal shielded and insulated wire cores 100 are distributed in a triangular shape and are twisted with each other to form the corresponding cable core 200.
[0031] In some embodiments of the example, the metal shielded and insulated wire core 100 specifically comprises a conductor 110, and the conductor 110 is sequentially covered with a conductor shielding layer 120, a plastic insulation layer 130, an insulation shielding layer 140 and a metal shielding layer 150 from inside to outside.
[0032] The conductor 110 is specifically a second type of tightly compressed circular stranded copper conductor.
[0033] Meanwhile, the conductor shielding layer 120, the plastic insulation layer 130, and the insulation shielding layer 140 can be co-extruded on the conductor 110, so that the insulation structure is stable and the insulation of the conductor 110 can be ensured.
[0034] The metal shielding layer 150 is wrapped around the insulation shielding layer 140 by overlapping copper strips, which is used to homogenize the electric field, shield external electromagnetic interference, and carry short-circuit current.
[0035] The comprehensive fireproof layer 300 in the present example comprises, from inside to outside, an inner thermal insulation layer 310, a fire-retardant oxygen barrier layer 320, an inner temperature-reducing fireproof layer 330, a middle thermal insulation layer 340, an outer temperature-reducing fireproof layer 350, and an outer thermal insulation layer 360.
[0036] The inner thermal insulation layer 310, the middle thermal insulation layer 340, and the outer thermal insulation layer 360 are formed by overlapping wrapping of glass fiber strips. The inner surface of the cross section of the inner thermal insulation layer 310 is triangular, and the three edges are tangent to the metal shielding and insulation wire core 100. Since there is no filler between the metal shielding and insulation wire core 100, the gaps are all air, which has good heat transfer and heat dissipation effects. The glass fiber strips have good thermal insulation and fire blocking effects, and can slow down the transmission of external heat to the cable core 200 during combustion. The inner thermal insulation layer 310 serves as the last thermal insulation and fire blocking line for the metal shielding and insulation wire core 100, and can effectively prevent external fire sources from directly hitting the metal shielding and insulation wire core 100 even if all the fireproof structures outside the inner thermal insulation layer 310 fail. The inner thermal insulation layer 310 and the metal shielding layer 150 serve as the last fireproof wall of the cable, effectively preventing the plastic insulation layer 130 from being burned, so that the plastic insulation layer 130 still has good insulation performance.
[0037] The fire-retardant oxygen barrier layer 320 is formed by extruding halogen-free low-smoke flame-retardant polyolefin oxygen barrier material. The oxygen barrier material has good fire-retardant and oxygen barrier effects, and can burn the flame to the cable core 200 during combustion.
[0038] The inner temperature-reducing fireproof layer 330 and the outer temperature-reducing fireproof layer 350 are formed by extruding mineral fireproof mud. This structure can release water during cable combustion, which has a significant effect on the cooling of the cable core 200. Since the main component of this structure is inorganic mineral, the structure becomes a hard shell after combustion, which has good fire-retardant, oxygen barrier, thermal insulation, and fire blocking effects.
[0039] Further, the fire-retardant oxygen barrier layer 320 is further formed with a plurality of uniformly distributed sawtooth protrusions on the outer surface. The sawtooth height is equivalent to the effective thickness of the fire-retardant oxygen barrier layer 320, the sawtooth width is equivalent to the groove width, and the width is 1.5-3 times the sawtooth height. Since the inner temperature-reducing fireproof layer 330 is relatively soft and is easily deformed and compressed under the action of external force and its own gravity during production, the fire-retardant oxygen barrier layer 320 and the inner temperature-reducing fireproof layer 330 are cross-fitted but can ensure that the inner temperature-reducing fireproof layer 330 has a uniform thickness and a stable structure in the groove of the fire-retardant oxygen barrier layer 320, and the inner temperature-reducing fireproof layer 330 extruded by the mineral fireproof mud also serves as a round filling part of the cable core 200. Since the thickness of the fire-retardant oxygen barrier layer 320 at the top of the three edges is very thin, when the cable is bent, the three metal shielded insulated wire cores 100 and the fire-retardant oxygen barrier layer 320 are mainly stressed, and the inner temperature-reducing fireproof layer 330 is less stressed, so the structure of the inner temperature-reducing fireproof layer 330 does not make the cable as a whole hard and affect the bending performance of the cable.
[0040] The protective layer 400 in the scheme of the present example is formed by overlapping and wrapping non-woven fabric. The non-woven fabric can effectively absorb the moisture released by the mineral fireproof mud, accelerate the structural stabilization and solidification of the outer temperature-reducing fireproof layer 350, and reduce the influence of the mineral fireproof mud released to the outside of the outer thermal insulation layer 360 on the next process.
[0041] The outer protective layer 500 in the scheme of the present example can be an extruded halogen-free low-smoke flame-retardant polyolefin sheath or a composite structure of a metal reinforcing layer and an extruded plastic sheath outside the metal reinforcing layer. The metal reinforcing layer can be a metal belt wrapping structure or a metal wire winding structure.
[0042] In the fire-retardant and fire-resistant medium-voltage power cable given in the present example, the fire-retardant oxygen barrier layer 320, the inner temperature-reducing fireproof layer 330, and the outer temperature-reducing fireproof layer 350 all contain mineral high-flame-retardant materials. After burning, the three layers can form a hard shell fireproof wall structure, which can better play the roles of fireproofing, temperature reduction, flame retardation, fire separation, heat insulation, and oxygen isolation. The structure of the outer temperature-reducing fireproof layer 350 is not uniform in burning, and cracks occur at places where the mineral fireproof mud is subjected to a large temperature difference. However, the fire-retardant oxygen barrier layer 320 and the inner temperature-reducing fireproof layer 330 are cross-fitted, which prevents the fire from entering the inside and slows down the temperature rise of the metal shielded insulated wire core 100 in the cable core 200, thereby having good fire resistance.
[0043] In addition, in the fire-retardant and fire-resistant medium-voltage power cable given in the present example, the inner thermal insulation layer 310, the fire-retardant oxygen barrier layer 320, the inner temperature-reducing fireproof layer 330, the middle thermal insulation layer 340, the outer temperature-reducing fireproof layer 350, and the outer thermal insulation layer 360 in the comprehensive fireproof layer 300 are all flame-retardant materials, which makes the present application have good flame-retardant performance.
[0044] Furthermore, in the fire-retardant fire-resistant medium-voltage power cable given in the present example, the metal shielding insulation wire core 100 of the cable core 200 is not filled with a filler, but is filled with a fire-retardant oxygen barrier layer 320 and an inner temperature-reducing fireproof layer 330 in a cross-fitting structure, the oxygen barrier layer and the fireproof layer of the structure play their respective advantages and make up for their respective shortcomings, effectively solve the problem of unstable structure of the flexible mineral fireproof layer outside, reduce the average thickness of the fireproof layer, improve the effective thickness of the fireproof layer, and effectively reduce the outer diameter of the cable.
[0045] The basic principle, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.
Claims
1. A flame-retardant fire-resistant medium voltage power cable, characterized in that, The power cable comprises a cable core, a comprehensive fireproof layer, a protective layer and an outer protective layer from inside to outside. The cable core comprises three metal shielded insulated wire cores which are twisted with each other. Each metal shielded insulated wire core comprises a conductor, and the conductor is sequentially covered with a conductor shielding layer, a plastic insulation layer, an insulation shielding layer and a metal shielding layer from inside to outside. The comprehensive fireproof layer comprises an inner heat insulation layer, a fire-retardant oxygen barrier layer, an inner temperature-reducing fireproof layer, a middle heat insulation layer, an outer temperature-reducing fireproof layer and an outer heat insulation layer from inside to outside.
2. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that The fire-retardant oxygen barrier layer is provided with a plurality of sawtooth protrusions which are uniformly distributed on the outer surface.
3. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that The inner heat insulation layer, the middle heat insulation layer and the outer heat insulation layer are formed by overlapping and wrapping glass fiber belts.
4. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that The fire-retardant oxygen barrier layer is formed by extruding and wrapping halogen-free low-smoke flame-retardant polyolefin oxygen barrier material.
5. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that, The inner temperature-reducing fireproof layer and the outer temperature-reducing fireproof layer are formed by extruding and wrapping mineral fireproof mud.
6. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that The protective layer is formed by overlapping and wrapping non-woven fabric.
7. A flame and fire retardant medium voltage power cable according to claim 1, c h a r a c t e r i s e d in that The outer protective layer is an extruded halogen-free low-smoke flame-retardant polyolefin sheath or a composite structure of a metal reinforcing layer and an extruded plastic sheath.
8. A flame and fire retardant medium voltage power cable according to claim 2, c h a r a c t e r i s e d in that The inner surface of the section of the inner heat insulation layer is triangular, and the three edges are tangent to the metal shielded insulated wire cores. The width of the adjacent two sawteeth is 1.5-3 times the height of the sawteeth.