High-strength cold-resistant UV-resistant lightweight medium-voltage overhead cable

Abstract

The utility model relates to the technical field of cables, in particular to a high-strength cold-resistant UV-resistant light-weight medium-voltage aerial cable, which comprises a cable core, and a shielding layer, an insulating layer, a reinforcing layer and an outer protective layer which are sequentially coated outside the cable core, and the shielding layer and the insulating layer are in double-layer co-extrusion and are tightly attached. The cable core adopts a molded wire aluminum alloy conductor, and the molded wire aluminum alloy conductor is formed by twisting and pressing a plurality of strands of drawn aluminum alloy. And the shielding layer is made of a thermosetting semi-conductive material. And the insulating layer is made of a high-cleanliness irradiation cross-linked polyethylene material. The reinforcing layer is formed by weaving high-strength aramid yarns, and a mixture of magnesium hydroxide and aluminum hydroxide is uniformly coated on the aramid yarns before the aramid yarns are woven, so that the flame retardant property of the aramid yarns is improved. The outer protection layer is made of a halogen-free low-smoke flame-retardant polyolefin sheath material which is weather-proof, anti-UV and high in flame-retardant performance. The cable meets the requirements of light weight, high flame retardant property, obviously improved creep resistance, cold resistance and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to cable technical field especially relates to a high strength cold resistant UV lightweight medium voltage overhead cable. BACKGROUND

[0002] At present, the overhead line adopted in China is divided into two kinds of bare conductor and insulated conductor. The bare conductor is generally used for long-distance power transmission of high voltage and is suitable for laying in places with few people, no high-rise buildings or vegetation. The overhead insulated conductor is generally used for power transmission and distribution system in cities and rural areas. Compared with the buried cable, the overhead insulated conductor has lower cost, does not need to construct underground pipe network, and is laid openly, which is convenient for maintenance and replacement.

[0003] At present, most of the overhead insulated cables used in China adopt aluminum core cable. When a larger tension needs to be borne, steel core aluminum stranded wire is used as the overhead insulated conductor. Since the density of the steel core is much greater than that of aluminum, although the overall breaking force (tensile strength) of the cable is obviously improved, the self-weight of the cable is increased, the laying becomes more difficult, and the span of the tower is denser compared with the overhead insulated cable without steel core. At the same time, as a conventional overhead insulated cable, since the insulation material adopts cross-linked polyethylene material, it does not have flame retardant property. When laying in cities or places with dense buildings, if the cable catches fire due to short circuit, it is easy to ignite the surrounding buildings, and the fire risk is high. At the same time, the aluminum conductor has fatal creep property, which greatly reduces the safety factor of the joint. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the purpose of the utility model is to provide a high strength cold resistant UV lightweight medium voltage overhead cable.

[0005] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0006] A high strength cold resistant UV lightweight medium voltage overhead cable, characterized in that it comprises a cable core and a shielding layer 2, an insulation layer 3, a reinforcing layer 4 and an outer protective layer 5 which are successively wrapped outside the cable core, the shielding layer 2 and the insulation layer 3 are double-layer co-extruded and tightly fitted.

[0007] The cable core adopts a profiled aluminum alloy conductor 1 which is tightly pressed by a plurality of drawn aluminum alloy strands.

[0008] The shielding layer 2 adopts a thermosetting semiconductive material.

[0009] The insulation layer 3 adopts high-purity irradiation cross-linked polyethylene material.

[0010] The reinforcing layer 4 is knitted by high-strength aramid yarn, and a mixture of magnesium hydroxide and aluminum hydroxide is uniformly coated on the aramid yarn before knitting, so that the flame-retardant property of the aramid yarn is improved.

[0011] The outer protective layer 5 is made of halogen-free low-smoke flame-retardant polyolefin sheath material with weather resistance, UV resistance and high flame retardance.

[0012] The high-strength cold-resistant UV-resistant lightweight medium-voltage overhead cable has the advantages that the self weight of the cable is greatly reduced while the tensile strength is met, the span of cable laying is improved, the laying cost is reduced, the insulation and protective layer of the polyethylene base material meet the use conditions of the cable in extremely cold climate, the structure that the reinforcing layer is coated with flame retardant and used together with the outer protective layer protects the cable and improves the flame retardant property of the cable, the local self-extinguishing or non-spreading performance of the cable is greatly improved, and the performance of the overhead insulated cable is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 The utility model discloses a structure schematic diagram.

[0014] In the drawing, the aluminum alloy conductor 1 is a profiled wire, the shielding layer 2 is a shielding layer, the insulation layer 3 is an insulation layer, the reinforcing layer 4 is a reinforcing layer, and the outer protective layer 5 is an outer protective layer. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments.

[0016] Material selection of embodiment 1

[0017] 1. Cable core: the cable core adopts an aluminum alloy conductor, is drawn according to the 6201 series high-strength aluminum alloy rod required by GB / T 3954-2014, is tightly pressed by a plurality of aluminum alloy strands, and has a smooth surface without burrs. The creep property of the aluminum alloy conductor is greatly improved compared to that of an aluminum conductor.

[0018] 2. Inner shielding layer 2+insulation layer 3: the inner shielding layer 2 adopts a thermosetting semiconductive material, the insulation layer 3 adopts high-cleanliness irradiation crosslinked polyethylene material, and the inner shielding layer and the insulation layer are double-layer co-extruded and tightly attached.

[0019] The irradiation crosslinked polyethylene is irradiation crosslinked, the long-term working temperature of the cable can reach 150 DEG C, the maximum short-circuit temperature can reach 250 DEG C, and the cable has excellent insulation performance and electrical performance. After irradiation, the cable has high aging resistance, chemical stability, strong environmental stress cracking resistance, high mechanical strength and good safety.

[0020] 3, the reinforcing layer 4: the reinforcing layer 4 is woven with high-strength aramid yarn, and a mixture of magnesium hydroxide and aluminum hydroxide is uniformly coated on the aramid yarn before weaving, so as to improve the flame retardant property of the aramid yarn.

[0021] The aramid yarn has the advantages of ultrahigh strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and the like. The strength of the aramid yarn is 5-6 times that of steel wire, and the weight of the aramid yarn is only about one fifth of that of steel wire. The aramid yarn does not decompose or melt, has good insulation and anti-aging properties, and has a long service life. The aramid yarn coated with the mixture of magnesium hydroxide and aluminum hydroxide makes up for the disadvantage of flammability and improves the flame retardant property.

[0022] 4, the outer protective layer 5: the outer protective layer 5 is made of halogen-free low-smoke flame-retardant polyolefin sheath material with weather resistance, UV resistance and high flame retardant property. The sheath material does not contain toxic and harmful substances such as lead salt and dioxin, and magnesium hydroxide and aluminum hydroxide are added as flame retardants to improve the flame retardant property of the cable and make the material environmentally friendly and safe. N660 carbon black is uniformly added in the material to increase the light aging resistance, i.e. weather resistance, of the material. Polyethylene is used as the base material of the polyolefin sheath, which inherits the low temperature performance of-76℃ and can withstand the test of severe cold weather.

[0023] Example 2 process scheme

[0024] 1. Cable core: the profiled wire aluminum alloy conductor 1 is adopted, and the tight pressing coefficient is close to 1. The outer diameter of the profiled wire aluminum alloy conductor 1 can be reduced by 10% compared with that of the conventional circular tight pressing conductor, thereby saving the amount of raw materials in subsequent processes and reducing the mass of the cable body. The surface of the profiled wire conductor is smooth, and the electric field intensity distribution on the surface of the conductor is uniform, thereby reducing the probability of discharge. The profiled wire conductor should not have the phenomena of missing strands, loose strands and broken strands, and the profiled wire conductor should be uniformly and tightly twisted, and the surface should be smooth without defects such as oil stains, burrs, sharp edges, scratches and protrusions.

[0025] 2, inner shield layer + insulation layer extrusion: the inner shield layer and the insulation layer are extruded by double-layer co-extrusion.

[0026] (1) The inner shield is made of thermosetting semiconductive material, and the insulation is made of high-purity irradiation crosslinked polyethylene material. The inner shield and the insulation are co-extruded by double-layer co-extrusion and closely attached. The eccentricity of the insulation is ≤8%, the nominal thickness of the insulation is the process required value, and the thinnest point of the insulation layer is not less than the nominal value × 90%-0.1mm. The surface is required to be smooth, without old glue, scratches and other defects.

[0027] (2) After extrusion, the insulation layer irradiation crosslinking process is completed on a high-frequency high-voltage electron accelerator. The inner insulation layer irradiation crosslinking process is completed on an AB-2.5 MeV high-frequency high-voltage electron accelerator, the high voltage is 3.0 MV, the transverse current is 3.4 A, the longitudinal current is 1.2 A, the large beam is discharged, and when the corresponding speed is 20 m / min, the heat extension and aging performance after irradiation can meet the technical requirements.

[0028] (3) Aramid fiber woven reinforcing layer: aramid fiber coated with a mixture of magnesium hydroxide and aluminum hydroxide is woven, the thickness of the woven layer is 0.4 mm, and the density of the woven layer is 50%. The density of the woven layer is controlled so that the outer protective layer can be in full contact with the inner insulation layer to prevent separation of the sheath and the insulation.

[0029] (4) Outer protective layer extrusion: a halogen-free low-smoke flame-retardant polyolefin sheath material with weather resistance, UV resistance and high flame retardance is used for extrusion, and an extrusion die is used for extrusion. The extrusion die greatly improves the extrusion pressure of the machine head, so that the outer protective layer can be fully bonded with the aramid fiber woven reinforcing layer and the insulation to prevent the sheath from loosening. The thinnest point of the protective layer is not less than the nominal value x 85%-0.1 mm, the surface of the sheath should be smooth and flat, and there should be no sharp corners, pits, burns or scratches, and no visible bubbles and sand holes on the cross section.

[0030] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. The replacement can be a partial structure, device, method step replacement, or a complete technical solution. According to the technical solution and the utility model concept of the present application, equivalent replacement or change should be covered within the protection scope of the present application.

Claims

1. A high strength, cold resistant, UV resistant, lightweight, medium voltage aerial cable, characterized in that: The cable core and the shielding layer (2), the insulation layer (3), the reinforcing layer (4) and the outer sheath (5) successively coated outside the cable core, the shielding layer (2) and the insulation layer (3) are double-layer co-extrusion and closely adhere.

2. A high strength, cold-resistant, UV-resistant, lightweight, medium voltage aerial cable according to claim 1, characterized in that: The cable core adopts a profiled aluminum alloy conductor (1) which is tightly twisted by a plurality of drawn aluminum alloy strands.

3. A high strength, cold-resistant, UV resistant, lightweight, medium voltage aerial cable according to claim 1, characterized in that: The shielding layer (2) adopts a thermosetting semiconductive material.

4. A high strength, cold-resistant, UV resistant, lightweight, medium voltage aerial cable according to claim 1, characterized in that: The insulation layer (3) adopts a high-cleanliness irradiation crosslinked polyethylene material.

5. A high strength, cold-resistant, UV resistant, lightweight, medium voltage aerial cable as claimed in claim 1, wherein: The reinforcing layer (4) adopts high-strength aramid yarn weaving, and a mixture of magnesium hydroxide and aluminum hydroxide is uniformly coated on the aramid yarn before weaving to improve the flame-retardant property of the aramid yarn.

6. A high strength, cold-resistant, UV resistant, lightweight, medium voltage aerial cable according to claim 1, characterized in that: The outer sheath (5) adopts a halogen-free low-smoke flame-retardant polyolefin sheath material with weather resistance, UV resistance and high flame retardance.

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