Low windage insulated cable

Abstract

The application discloses a kind of low wind resistance insulated cable, including conductor layer and outer protective layer, both mutual combination is used to play role, outer protective layer includes insulating layer, conductor shielding layer, insulating layer surface is equipped with drop type structure, drop type structure is the annular array groove of insulating layer surface, the curvature radius of two end arcs of groove is 2.4mm, the depth of groove is 1.09mm, the number of annular array groove on insulating layer surface is 12, the opening angle of groove is 30 °, wind resistance performance is far superior to existing insulated cable on market, by special setting of insulating layer surface structure parameter, realize the best structure state, so as to reach 0.75 wind resistance coefficient.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of overhead insulated cables, in particular to a low wind resistance insulated cable. BACKGROUND

[0002] Typhoons often cause large-scale power transmission and distribution line tripping, tower collapse, and wire breakage, and storms also bring great difficulties to repair and fault recovery. Although the impact of wind speed is generally considered in the design of overhead power grids, when the wind speed exceeds a certain value, the mechanical load of the line equipment in the windward horizontal direction will increase, which is prone to short circuit accidents and poses an objective threat to the safe operation of overhead transmission lines.

[0003] Low wind resistance cables help reduce the impact of wind on cables. In the case of the same cable diameter, compared with traditional steel-cored aluminum stranded wires, low wind resistance cables have a smaller wind resistance coefficient, i.e. bear smaller wind load.

[0004] Although the above-mentioned domestic and foreign patents disclose relevant content about low wind resistance cables, most of them are low wind resistance designs of bare cables, and there are also corresponding low wind resistance designs of overhead insulated cables. However, the low wind resistance structure shape of the above-mentioned designs cannot significantly improve the low wind resistance effect of insulated cables after wind tunnel test. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a low wind resistance insulated cable to solve the above problems.

[0006] To achieve the above purpose, the present application realizes the following technical solutions.

[0007] A low wind resistance insulated cable, comprising a conductor layer and an outer protective layer, the outer protective layer being wrapped outside the conductor layer, the conductor layer comprising a plurality of aluminum single wires, the outer protective layer comprising an insulation layer and a conductor shielding layer, the surface of the insulation layer being provided with a water-drop-shaped structure, the water-drop-shaped structure being a ring array of grooves on the surface of the insulation layer, the curvature radius of the circular arcs at both ends of the grooves being 2.4 mm, the depth of the grooves being 1.09 mm, the number of the ring array of grooves on the surface of the insulation layer being 12, and the opening angle of the grooves being 30°. The wind resistance performance of the low wind resistance insulated cable is far superior to that of existing insulated cables on the market. By specially setting the structure parameters of the surface of the insulation layer, the optimal structure state is achieved, so that the wind resistance coefficient can reach 0.75.

[0008] Preferably, the conductor layer comprises 37 aluminum single wires.

[0009] Preferably, the diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of the conductor layer is 244.39 mm 2 .

[0010] Preferably, the insulating layer is made of cross-linked polyethylene.

[0011] Preferably, the average thickness of the insulating layer is not less than 3.40 mm, and the minimum thickness is not less than 2.96 mm, and the maximum eccentricity is 15%.

[0012] Preferably, the conductor shielding layer comprises a base material and carbon black.

[0013] Preferably, the conductor shielding layer is a non-metallic layer extruded on the conductor layer.

[0014] Preferably, the non-metallic layer is at the same potential as the aluminum single wire.

[0015] Preferably, the average thickness of the conductor shielding layer is 0.60 mm, and the minimum thickness is 0.44 mm.

[0016] Preferably, the base material is a cross-linked semiconductive inner shielding material.

[0017] Compared with the prior art, the low wind resistance insulated cable disclosed by the present application comprises a conductor layer and an outer protective layer, which are used in combination to play a role, and the outer protective layer comprises an insulating layer and a conductor shielding layer, the surface of the insulating layer is provided with a water drop type structure, the water drop type structure is a groove in a ring array on the surface of the insulating layer, the curvature radius of the circular arc at both ends of the groove is 2.4 mm, the depth of the groove is 1.09 mm, the number of grooves in the ring array on the surface of the insulating layer is 12, and the opening angle of the groove is 30°. The wind resistance performance is far superior to that of existing insulated cables on the market. Through special setting of the surface structure parameters of the insulating layer, the best structure state is realized, so that a wind resistance coefficient of 0.75 can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a structural schematic diagram of the low wind resistance insulated cable of the present application;

[0019] Figure 2 FIG. 2 is a structural schematic diagram of a general round cable of the present application;

[0020] Figure 3 FIG. 3 is a structural schematic diagram of a golf type cable of the present application;

[0021] Figure 4 FIG. 4 is a structural schematic diagram of a sand dune type cable of the present application;

[0022] Figure 5 Wind resistance coefficient diagram of low wind resistance insulated cable of different shapes of the present application;

[0023] Figure 6 Structure diagram of R2d1.2C8 type insulated cable of the present application;

[0024] Figure 7 Structure diagram of R2d1.2C10 type insulated cable of the present application;

[0025] Figure 8 Structure diagram of R2d1.2C12 type insulated cable of the present application;

[0026] Figure 9 Structure diagram of R2d1.5C10 type insulated cable of the present application;

[0027] Figure 10 Structure diagram of R0.6d1.2C8 type insulated cable of the present application;

[0028] Figure 11 Structure diagram of R0.6d1.2C10 type insulated cable of the present application;

[0029] Figure 12 Structure diagram of R0.6d1.2C12 type insulated cable of the present application;

[0030] Figure 13 Structure diagram of R2.4d1.09C12 type insulated cable of the present application;

[0031] Figure 14 Structure diagram of general insulated cable of the present application;

[0032] Figure 15 Wind resistance coefficient diagram of low wind resistance insulated cable of different slot numbers of the present application;

[0033] Figure 16 Wind resistance coefficient diagram of low wind resistance insulated cable of different curvature radii of the present application;

[0034] Figure 17 Wind resistance coefficient diagram of low wind resistance insulated cable of different groove depths of the present application;

[0035] Figure 18 Wind tunnel test result diagram of wind resistance performance verification test of the present application;

[0036] Figure 19 Simulation experiment diagram of low wind resistance insulated cable of the present application under 10 m / s wind speed;

[0037] Figure 20 Simulation experiment diagram of low wind resistance insulated cable of the present application under 15 m / s wind speed;

[0038] Figure 21 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 20 m / s;

[0039] Figure 22 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 25 m / s;

[0040] Figure 23 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 30 m / s;

[0041] Figure 24 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 35 m / s;

[0042] Figure 25 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 40 m / s;

[0043] Figure 26 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 45 m / s;

[0044] Figure 27 Figure is a simulation experiment diagram of the low wind resistance insulated cable of the present application under a wind speed of 50 m / s. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all.

[0046] A low wind resistance insulated cable comprises a conductor layer and an outer protective layer, the outer protective layer is wrapped outside the conductor layer, the conductor layer comprises a plurality of aluminum single wires, the outer protective layer comprises an insulation layer and a conductor shielding layer, the surface of the insulation layer is provided with a water-drop-shaped structure, the water-drop-shaped structure is a groove in a ring array on the surface of the insulation layer, the curvature radius of the circular arc at both ends of the groove is 2.4 mm, the depth of the groove is 1.09 mm, the number of the grooves in the ring array on the surface of the insulation layer is 12, and the opening angle of the groove is 30°.

[0047] The conductor layer comprises 37 aluminum single wires, the diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of the conductor layer is 244.39 mm 2 .

[0048] The insulation layer is made of cross-linked polyethylene, the average thickness of the insulation layer is not less than 3.40 mm, the thickness at the thinnest part is not less than 2.96 mm, and the maximum eccentricity is 15%.

[0049] The conductor shielding layer comprises a base material and carbon black.

[0050] The conductor shielding layer is a non-metallic layer extruded on the conductor layer, the non-metallic layer is equipotential with the aluminum single wire, and the average thickness of the conductor shielding layer is 0.60 mm, and the thinnest thickness is 0.44 mm.

[0051] The base material is a cross-linked semiconductive inner shielding material.

[0052] The outer layer strand is a low wind resistance cable with a fan-shaped cross section, and through field tests, it is found that in the wind speed range of 30-60 m / s, the wind resistance coefficient can be reduced to less than 70% of that of ordinary cables, and four types of grooved cables are taken as research objects, and it is shown that in the interval of 10-20 m / s, the wind resistance coefficient of the cable increases linearly with the increase of the roughness of the cable cross section. In the interval of 20-60 m / s, the wind resistance coefficient of the cable is determined by the quadratic function of two variables composed of the number of cross section grooves and the groove radius.

[0053] The convex arc of the outer layer single wire of the low wind resistance cable is changed to a concave arc, and the wind resistance coefficient of the cable is reduced through the design of the concave arc depth. For insulated cables, the surface shape of the insulation layer can be optimized by fluid mechanics turbulence theory to effectively reduce wind resistance. At present, due to the influence of the special-shaped extrusion process of the insulation layer, there are few research results on low wind resistance insulated cables at home and abroad, and the research on low wind resistance insulated cables is still in its infancy. Therefore, according to the following experiments, the process of obtaining the best type is as follows:

[0054] S1, according to the theory of cylindrical flow, the surface of the insulation layer is simulated to be golf-shaped, water-drop-shaped and sand-dune-shaped, and the specific analysis steps are as follows:

[0055] For the golf-shaped surface structure, the water-drop-shaped structure of free-fall motion, and the sand-dune-shaped structure of this rise and that fall, the insulation layer surface structure is designed, and the three kinds are compared with ordinary insulated cables through CFD simulation. In the CFD simulation, the low wind resistance insulated cable turbulence model selects Shear Stress Transport k- ε Model, adopts finite volume method and SIMPLEC algorithm for solution, and the momentum, turbulent kinetic energy k and turbulent dissipation rate ε are discretized by second-order precision, and the air density and viscosity are default values. The cable model size is consistent with the actual size. (When simulating, the wind speed is from 10 m / s to 50 m / s, the interval is 5 m / s, and the wind deflection angle is 90°). Through CFD simulation, it can be concluded that the wind resistance performance of the low wind resistance insulated cable is better than that of the ordinary round cable at a wind speed of 20 m / s or more, and among them, the wind resistance coefficient of the water-drop-shaped insulated cable decreases obviously with the increase of wind speed at 20 m / s-50 m / s, which is better than the other three kinds of cables.

[0056] ①When the imitation golf surface has a dent, the dent promotes the occurrence of turbulent flow transition, the turbulent boundary layer is not prone to flow separation phenomenon, thus the low pressure area behind the ball is small, the resistance is reduced, and the distance of the golf ball flight is increased;

[0057] ②The imitation water droplet type of free fall motion is a streamlined body, characterized by a smooth front and a gentle back, thereby reducing the pressure difference resistance of the flow around the object;

[0058] ③The force receiving part with large wind resistance of the imitation sand dune type will gradually deform, and eventually form a shape with the smallest wind resistance. The formation of this shape is conducive to the flow of wind, i.e. the flow resistance of wind is small.

[0059] Then, different numbers of grooves, groove depths, and curvature radii of the arc at both ends of the groove of the imitation water droplet type structure are designed, and the actual objects are made. The wind tunnel experiment is compared with the ordinary round cable. The cable is made by frame stranding machine and extruder, and the wind tunnel experiment is carried out in the low-speed return flow wind tunnel laboratory. The laboratory can produce wind speed of 0m / s-60m / s, and the wind field is uniform and the wind speed is continuously adjustable. The wind tunnel experiment wind speed loading interval is 5m / s, the sampling frequency is 1000Hz, the sampling time is 30s, the cable length is 1m, and it is fixed on the support. The support is equipped with a six-dimensional force measuring balance. According to the force received by the support before and after the experiment, the wind resistance of the cable can be obtained. The wind resistance coefficient of the cable is calculated as follows: Wherein, C d is the wind resistance coefficient of the cable, F D is the resistance received by the cable, ρ is the air density, V is the actual wind speed, D is the diameter of the cable, L is the effective length of the cable. Through the wind tunnel experiment of different imitation water droplet type cable and ordinary insulated cable, it is found that the depth of the groove and the curvature radius of the arc at both ends of the groove have greater gain on the wind resistance, and too deep groove even has a negative effect on the wind resistance; for the number of grooves, by comparing the calculation data of different groove numbers under the same groove shape, it is found that the groove number is negatively related to the wind resistance.

[0060] First, study the influence of the number of grooves on the wind resistance coefficient of low wind resistance insulated cable. The number of grooves is equal to 360° divided by the opening angle of the cable surface. Due to the limitation of processing technology and installation grip strength requirement, the number of grooves is generally set to be even and not more than 12. Therefore, four kinds of cable models are designed for comparison and analysis, in which the curvature radius R of the arc at both ends of the groove is 0.6mm, the groove depth d is 1.2mm, and the groove number C is 6, 8, 10 and 12 respectively. As shown below Figure 15 The cable wind resistance coefficient under different groove numbers can be obtained, and it can be concluded that when the wind speed is greater than 25m / s, the more the groove number, the lower the wind resistance coefficient.

[0061] Second step, study the curvature radius of the two ends of the groove on the wind resistance coefficient of low wind resistance insulation cable. Due to the limitation of processing technology and the thickness of the insulation layer is generally 3mm-3.4mm, so the curvature radius of the two ends of the groove is generally 0.6mm-2mm. Therefore, two cable models are designed for comparative analysis, in which the groove depth d is 1.2mm, the groove number C is 12, and the curvature radius R is 0.6mm and 2mm respectively. As shown below Figure 16 The wind resistance coefficient of the cable under different curvature radius is shown in the following

[0062] Third step, study the effect of groove depth on the wind resistance coefficient of low wind resistance insulation cable. Because too deep groove will reduce the contact area of the fittings, resulting in installation grip problem, so when the groove number is not more than 10, the groove depth is generally not more than 1.5mm, and when the groove number is not more than 12, the groove depth is not more than 1.2mm. Therefore, three cable models are designed for comparative analysis, in which the curvature radius R is 2mm, the groove number C is 12, and the groove depth d is 1mm, 1.2mm and 1.5mm respectively. As shown below Figure 17 The wind resistance coefficient of the cable under different groove depth is shown in the following

[0063] In summary, the curvature radius and groove number of the surface structure of water drop type insulation cable are inversely proportional to the wind resistance coefficient. The groove depth is proportional to the wind resistance coefficient at low wind speed, and the groove depth is about 1.2mm at high wind speed, which is the best wind resistance coefficient. At the same time, due to the limitation of the size of the insulation layer, processing technology, installation grip requirement and other conditions, when developing low wind resistance insulation cable, all structural parameters need to be considered comprehensively.

[0064] Finally, according to the design results of structural parameters and the demand of strong wind resistance, R2d1.2C8, R2d1.2C10, R2d1.2C12, R2d1.5C10, R0.6d1.2C8, R0.6d1.2C10, R0.6d1.2C12, R2.4d1.09C12, eight kinds of water drop type low wind resistance insulation cable are selected, and together with nine kinds of ordinary round wire insulation cable, wind resistance performance verification test is carried out.

[0065] The wind resistance performance verification test, i.e. wind tunnel test, is as follows Figure 18 As shown in the following Figures 19-27The simulation experiment graphs of R2.4d1.09C12 type water-drop-shaped low wind resistance insulation cable from 10 m / s to 50 m / s are shown in sequence, and finally it is concluded that the R2.4d1.09C12 type (the curvature radius is 2.4 mm, the groove depth is 1.09 mm, the groove number is 12, and the opening angle is 30°) water-drop-shaped low wind resistance insulation cable has the best wind resistance performance, which is more than 30% higher than that of the ordinary insulation cable.

[0066] The insulating layer is made of black cross-linked polyethylene, the average thickness is at least 3.40 mm, the minimum thickness is 2.96 mm at the thinnest part, and the maximum eccentricity is 15%. The insulating eccentricity calculation formula is: The conductor shielding layer is a non-metal layer extruded on the cable conductor and is at the same potential as the conductor. The average thickness is 0.60 mm, and the minimum thickness is 0.44 mm. The base material of the conductor shielding layer is cross-linked semi-conductive inner shielding material, which is usually consistent with the material of the conductor, and the density is 1.2 g / cm 3 .

[0067] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0068] It should be noted that the terms "first", "second", and the like, as used in the specification and the claims herein, are intended to modify a particular aspect of the application, but do not require a particular order or sequence of the aspects. It will be understood that the use of such terms as "first", "second", and the like, are used to distinguish between two or more aspects of the application, but do not otherwise limit the scope of the application.

[0069] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A low windage insulating cable characterized by: The utility model provides a kind of cable, including conductor layer and outer protective layer, the outer protective layer is wrapped outside conductor layer, the conductor layer includes several aluminum single wires, the outer protective layer includes insulating layer, conductor shielding layer, the insulating layer surface is equipped with water drop type structure, the water drop type structure is annular array of recess on the surface of insulating layer, the curvature radius of the circular arc of recess two ends is 2.4mm, the depth of recess is 1.09mm, the number of annular array of recess on the surface of insulating layer is 12, the opening angle of recess is 30 °, the insulating layer is made of crosslinking polyethylene, the average thickness of insulating layer is not less than 3.40 mm, the thickness of thinnest place is not less than 2.96 mm, the maximum eccentricity is 15%, the conductor shielding layer includes matrix material and carbon black, the conductor shielding layer is nonmetallic layer extruded on conductor layer, the nonmetallic layer is equipotential with aluminum single wire, the average thickness of conductor shielding layer is 0.60mm, the thickness of thinnest place is 0.44mm, and the matrix material is crosslinking semiconductive inner shielding material.

2. The low wind resistance insulated electrical cable of claim 1, wherein: The conductor layer includes 37 aluminum single wires.

3. The low wind resistance insulated electrical cable of claim 2, wherein: The diameter of the aluminum single wire is 2.9 mm, and the cross-sectional area of the conductor layer is 244.39 mm 2 .

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