Overhead cable for the transmission of low-voltage and medium-voltage electric power and digital signal, aluminum alloy concentric conductors with a fiber-optic cable inside and drawn wire treatment process
10845557 · 2020-11-24
Inventors
Cpc classification
International classification
G02B6/44
PHYSICS
Abstract
An overhead cable for the transmission of low-voltage and medium-voltage energy and digital signals, including a central fiber-optic cable, surrounded by a protective covering of the central fiber-optic cable and around such protective covering of such fiber optics by at least an aluminum alloy layer for the transmission of low-voltage and medium-voltage electric power or neutral wire and the covering thereof, where at least one aluminum alloy layer includes a 6101 aluminum alloy wire that has been heat treated, submitting the same to a temperature within a range of 260 and 300 C. and a treatment process for the aluminum alloy drawn wire.
Claims
1. An overhead cable for transmission of low-voltage and medium-voltage electric power and digital signals, comprising: a central fiber-optic cable; a protective covering surrounding the central fiber-optic cable; and around and covering the protective covering of the central fiber-optic cable, at least one aluminum alloy layer for the transmission of low-voltage and medium-voltage electric power, wherein the at least one aluminum alloy layer comprises a 6101 aluminum alloy wire that has been heat treated to a temperature within a range of 260 and 300 C. to improve an elongation and inhibit breaking of the central fiber-optic cable contained within the aluminum alloy layer, and wherein the protective covering comprises a protective covering material selected from the group consisting of: cross-linked low-density polyethylene (XLPE), medium-density polyethylene (MXLPE), high-density polyethylene (HDXLPE), polypropylene (PP), Polyvinyl chloride-based compounds (PVC), Ethylene-vinyl acetate (EVA)-based compounds, and Ethylene propylene rubber-based elastomer compounds (EPR).
2. The overhead cable in accordance with claim 1, wherein the central fiber-optic cable is multi-fiber.
3. The overhead cable in accordance with claim 2, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least two aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
4. The overhead cable in accordance with claim 2, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least three aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
5. The overhead cable in accordance with claim 2, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least four aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
6. The overhead cable in accordance with claim 1, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least two aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
7. The overhead cable in accordance with claim 6, wherein the at least two aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power are crowns.
8. The overhead cable in accordance with claim 7, wherein between each one of the at least two aluminum alloy layer crowns there is an insulating layer covering for electrically insulating the aluminum alloy layers.
9. The overhead cable in accordance with claim 8, wherein external to the insulating layer covering, there is an external insulating layer covering for insulating the overhead cable from the environment.
10. The overhead cable in accordance with claim 8, wherein the insulating layer covering for electrically insulating the aluminum alloy layers comprises a material selected from the group consisting of: low-density polyethylene (PELD), medium-density polyethylene (PEMD), high-density polyethylene (PEHD), cross-linked low-density polyethylene (HDXLPE), polypropylene (PP), Polyvinyl chloride-based compounds (PVC), Ethylene-vinyl acetate (EVA)-based compounds, and Ethylene propylene rubber-based elastomer compounds (EPR).
11. The overhead cable in accordance with claim 10, wherein the material for the insulating layer covering for electrically insulating the aluminum alloy layers is anti-tracking.
12. The overhead cable in accordance with claim 1, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least three aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
13. The overhead cable in accordance with claim 1, wherein the at least one aluminum alloy layer around the protective covering of the central fiber-optic cable comprises at least four aluminum alloy layers for the transmission of low-voltage and medium-voltage electric power.
14. The overhead cable in accordance with claim 1, wherein the at least one aluminum alloy layer comprising the 6101 aluminum alloy wire has been heat treated to a temperature within a range of 260 and 300 C. during a minimum period of 6 to 8 hours.
15. The overhead cable in accordance with claim 1, wherein the protective covering material for the protective covering of the central fiber-optic cable is anti-tracking.
16. The overhead cable in accordance with claim 1, wherein the at least one aluminum alloy layer has drawn wire.
17. A 6101-aluminum alloy drawn wire treatment process of up to 5.95 mm in diameter, comprising steps of: (i) introducing the 6101-aluminum alloy drawn wire of a diameter up to 5.95 mm in coils or baskets, such that the coils or baskets are delivered from a drawing machine into an air furnace at atmospheric pressure at a temperature within a range of 260 C. and 300 C.; (ii) leaving the 6101-aluminum alloy drawn wire in the furnace until reaching thermal equilibrium during 6 to 8 hours; (iii) taking the 6101-aluminum alloy drawn wire out of the furnace as coils or baskets after stages (i) to (ii) and leave the 6101-aluminum alloy drawn wire to cool down to ambient temperature.
18. The treatment process for the 6101-aluminum alloy drawn wire in accordance with claim 17, wherein in case a second drawing process is required, at diameters lower than 1.70 mm, the wire obtained in step (iii) is left at the ambient temperature for 48 hours before the second drawing to allow rearrangement of the crystallographic structure; then, steps (i), (ii) and (iii) are repeated.
Description
BRIEF DESCRIPTION OF FIGURES
(1) For a better understanding of this description, some illustrations have been attached hereto, which outline the main components and the space arrangement of the electric power cable with fiber optics of this invention. Such illustrations are presented as an example of a specific configuration, but they are not exhaustive of the possibilities of the invention fundamental concept.
(2)
(3)
(4)
(5)
(6)
(7)
DETAILED DESCRIPTION OF THE INVENTION
(8) As indicated above, the invention cable comprises an overhead cable for the distribution of energy containing an optical fiber core which is separated by plastic insulating layers, manufactured, for example, with cross-linked polyethylene (or any other of the materials indicated below), and has also two to four aluminum alloy layers. Such layers are concentric with the central optical fiber.
(9) The wire layers comprise an aluminum alloy that absorbs the mechanical strains of the overhead installation, and they have conductivity suitable for the transmission of high values of electric power with a low level of energy losses, caused by the heat generated in the conductors. The cable expansions and contractions are within the safe operation range of the fiber-optic cable. The thicknesses of the insulating covering allow the operation of the cable in overhead low-voltage three-phase lines or in three-phase lines with a neutral wire. With external insulations resistant to tracking and adequate thicknesses allow the cable operation in protected overhead medium-voltage lines.
(10) Cable elongations are produced by mechanical strains due to the action of wind and by its own weight, as well as for the typical variation of temperature in the cable itself due to the heating caused by currents circulating through the aluminum layers and the ambient temperature variation. The cable final temperature results from the dissipation of heat and the ambient temperature. The short-circuit currents should be limited to avoid excessive heating of the wires and the resulting excessive expansion of the cable for the temperature. A service temperature for continuous service and a maximum short-circuit temperature are set to 5 seconds.
(11) The thicknesses of the insulating covering ensure the low-voltage dielectric rigidity tests between layers, are resistant and distribute the mechanical strains of the metal layers towards the cable inside. For use in low-voltage cables, for each metal layer circulates the current of each of the three-phase system phases. For medium-voltage use, the phases on each end of the connection are short-circuited. The current is distributed to the layers proportionately, all the cable is at the same voltage as the ground, the cable is mounted on insulators and the outer covering is resistant to accidental contacts with grounded elements for short periods of time.
(12) The inner layer design has two characteristics: it is an enclosed layer whose number of wires and diameter have a cross-section that is equal to or higher than the one required for the electrical resistance requested, and also the enclosed layer absorbs radial stresses.
(13) The outer layer design has two characteristics: it is an enclosed layer whose number of wires and diameter have been selected to meet a cross-section that is equal to or higher than the one required for meeting the electrical resistance requested. The passage of cables is adjusted to cover the cable 95% minimum of its layer. The layer obtained by the enclosed cables of the aluminum alloy wires prevents the penetration of objects. Such property allows referring to it as cable to prevent a fraudulent connection to the electric system.
(14) The 6101 aluminum alloy wires have a specific heat treatment that confers ductility and resistance to bending fatigue stress. The aluminum alloy wires, based on IEC 60104, are only resistant to the wrapping test, and do not support being wrapped and unwrapped again.
(15) The wire ductility is required for mounting the cable inside the cabinets. The cable must be flexible and malleable, the curvature radios required inside the cabinet are not compatible with the usual materials for overhead lines. The tampered wires are not arranged to a final position, have elastic memory (i.e., act as a spring) and trend to release from their connectors.
(16) The electrical safety of users and installers of the electric power cable is achieved through dielectric tests on the cable and the installation, as contemplated in electrical regulations.
(17) The electrical safety of users and installers of the fiber-optic cable is achieved by the distance between the live parts and the installer. The fiber-optic cable is separated from the metal layers and is conducted to a cabinet that is separated from the low-voltage parts. The cable joints and derivations are performed inside the specific cabinet. In case the medium-voltage cables are used, the layer covering of the fiber-optic cable must be of an insulating material that is resistant to tracking to go from the medium-voltage area to the distribution cabinet without any voltage.
(18) Cable Elongation
(19) For the electrical grid sections up to 70 m, where the cable is retained with forces lower than 300 daN, the elongation is produced by thermal expansion. The literature indicates for the aluminum and its alloys a thermal expansion coefficient of 2310.sup.6 (1/ C.). For a cable whose manufacturing temperature is of 30 C. and the operation temperature is of 90 C. Thermal expansion of the cable 2310.sup.6 (1/ C.)(90-30) ( C.)=0.0014=>0.14%. For the case of a short-circuit increasing the temperature of the 3 phases to 160 C., the thermal expansion is 2310.sup.6 (1/ C.)(160-30) ( C.)=0.00299=>0.3%. A fiber-optic cable operates in optimal conditions up to 0.3% of its expansion (or 0.6%, as determined by other authors). For the retention forces in this case, the crowns operate within the range of application of the elastic limit of metals (Hooke's Law).
(20) The literature indicates for the 6101-aluminum alloy elasticity module it is 60000 MPa.
(21) Heat treatment of 6101 Aluminum Alloy wires.
(22) The IEC 60104 standard defines 6201 & 6101 aluminum alloy wires, their condition is hard due to the mechanical work and heat treatment (usually 4 hours between 160 and 180 C.). Such drawn and heat-treated wires of alloy type B (A6101) have 53% conductivity with respect to the copper (32.53 ohm.Math.mm2/km), 295 MPa breaking strain, ultimate elongation of 3.5%, specific weight of 2.73 kg/dm3 and a low malleability: as a result, this alloy fails to the bending fatigue stress. The IEC 60104-based wire is used for overhead electric power lines where the malleability is not a requirement for the manufacturing, installation, and use of the cable in overhead lines.
(23) The low malleability is related to the heat treatment.
(24) Unexpectedly, it has been found that a new treatment, through which the drawn wires of the alloy mentioned above are subject to a temperature within a range of 260 and 300 C. and a minimum heat treatment time of 6 to 8 hours to such temperature within a range of 260 and 300 C., the distribution of the chemical alloying elements of such alloy are changed (Si and Mg) within the crystalline structure by thermal agitation. As a result, improved plasticity and conductibility are obtained. The wire under such treatment improves the ultimate elongation (5%), conductivity (58.5% with respect to the copper), reaching a volumetric resistivity of 29.5 ohm.Math.mm2/km, and a lower breaking load is obtained with values of about 200 MPa, and malleability is recovered (with which it has resistance to bending fatigue stress). This last property is very much valued for the installation as it allows manipulating wires without breaking them.
(25) The wire thus obtained is used for conforming conductive layers, protecting the concentric multi-layer cable that is described in this invention.
(26) An Example of the Aluminum Alloy Wire Obtained Used for the Tests Performed
(27) The wire drawing process of the 6101-aluminum alloy wire to a final diameter and later heat treatment of artificial aging (by precipitating alloying elements), is part of the 6101A/T4 aluminum alloy wire rod, traction 158-170 MPa, Conductivity 51.8% IACS. The wire rod of 9.60 mm diameter is drawn in a drawing machine (with or without slipping) with mineral oil lubricant with 26% of reduction due to the passage until reaching 1.7 mm of final diameter. A metal coil or basket is obtained. When the final diameter is obtained, it is put inside an air furnace at atmospheric pressure and in a temperature between 260 C. and 300 C., once the furnace thermal equilibrium has been achieved, it is left in such regime for 6-8 hours. Then, the coils or baskets are taken out of the furnace and cooled at ambient temperature. Preferably, the wire is allowed to stand 48 hours before the second drawing at lower diameters, with which, the crystallographic structure may rearrange at ambient temperature. Samples are taken for testing, diameter, mechanical tension, ultimate elongation, volumetric resistivity and wrapping.
(28) After the second drawing, the heat treatment steps are repeated, as indicated above, conferring the wire the properties sought, such as, they do not present any elongation and, thus, it allows they may be inserted in cables together with the fiber optics without breaking it.
(29) The manner to determine the malleability of the wires for their later use in wiring and after that in the end product installation was performed as follows: Perform the winding test on its own diameter three subsequent times on the same probe, as follows: wind 8 turns, unwind 6 turns, wind 6 turns, unwind 6 turns, wind 6 turns; at the end of the test the wire has not broken or cracked.
(30) To achieve diameters lower than 1.70 mm until reaching 0.5 mm, it is drawn again with a wire drawing machine with 26% of reduction for passage with mineral oil lubricant or synthetic or semi-synthetic oil dissolved in water and then, for the final diameter, the heat treatment mentioned above is repeated. The draws to be used may be sintered diamond, natural diamond or tungsten carbide, the reduction angles may be between 16 and 20, the length of the cylinder may be between 20% and 30% of the diameter.
(31) The aluminum drawn wire that is heat treated as indicated above has properties that make it unique for its use for manufacturing any type of low-voltage and medium-voltage cables.
(32) Full Cable Production Process
(33) The fiber-optic cable must be compliant with the applicable IEC standard. The cable must have the protective covering indicated above; otherwise, it must be applied with any of the indicated insulating materials. The diameter on the covering defines the design of the layers. The diameter on the protective covering must be smooth, uniform, without any protrusions or deformations, maximum out-of-roundness of 5%.
(34) The aluminum alloy wires are installed on the fiber optics on a rigid strander (without any wire de-torsion) or planetary stranding (with wire de-torsion). The coil size containing the wire should be of a size as defined in DIN 400 for 1.70 mm wires and DIN 250 for diameters lower than 1.70 mm. Brakes must be adjusted in a manner to obtain a uniform surface on the wires installed, without any loose wires protruding the assembly. The appropriate tension required for tightening the wires during the cable installation is of 1 daN/mm.sup.2, the appropriate tension for the fiber-optic cable cover should be provided by its supplier. The application of polyester helical wrapping to fasten the aluminum alloy wires and facilitate the following process is recommended. The subsequent layers must be stranded with alternate directions to avoid the rotation of the cable during the assembly. Testing the electrical resistance of the layer at the beginning of the cable installation process is suggested. Dielectric rigidity tests of 3 kV A.C. may be performed for 5 minutes between metal layers insulated between each other with insulated material to check for the quality of the insulation process.
(35) The insulation extrusion process is performed in an insulation extrusion line for cables. The use of an extruder is advised with a minimum screw and barrel diameter of 60 mm. A screw profile suitable for processing the compound to be used. The use of extrusion dies of the so called tube method where the compound is stretched and applied uniformly on the metal layer. Uniform thicknesses are preferred to perfect circular geometric figures. The use of a device is advised to decrease the atmospheric pressure inside the extrusion crosshead where the cable to cover goes through, to achieve a higher adherence of the covering to the layer. This device is usually a pipe with a T-derivation where suction is applied to achieve the depression inside the crosshead. Checking for the absence of failures by means of the voltage test between electrodes, based on the IRAM NM 244 or IEC 60092-350 annex D standard, or equivalent is advised. It is advisable for the diameters of the drums of reels should be at least 20 times the diameter of the layer or of the respective cover.
(36) The drawing process, cable installation and extrusion process is repeated as many times as required for building the cable with the predefined layers. When the cable has been completed the ordinary tests for measurement of the electric resistance of the layers must be performed, as well as the dielectric rigidity test in water for the outer layer and the inner cable layers.
(37) Design of Concentric Crowns
(38) In this cable, the nominal section of the concentric metal layer and the value of the electrical resistance are the same for all the layers.
The increment of stranding of the (ic) layer is defined as (ic)=1/cos().(1)
(39) Lay length (P) is defined as the stranding length of the layer in (mm).
(40) (Dais) is defined as the diameter on the covering where the layer has been seated, in (mm).
(41) The wire diameter in the layer (crown) (d) is in (mm).
(42) The angle () has been defined as the angle between the cable axis and the tangent of the wires arranged in the concentric layer helix.
(43) Based on the considerations above, it is compliant:
Passage (P)=3.1416(Dais+d)/tg()(2)
(44) The design process begins with the passage of cables in 14Dais for the inner layer, 12Dais for the immediately adjacent layers and 10Dais for the outer layer.
(45) By solving tg() in the equation (2), the angle () is obtained by means of the following calculation: arc.Math.tg(), and, finally, 1/cos() is calculated.
(46) We defined the (Cob) coverage as the portion of the insulation surface (Dais) covered by the metal layer.
(47) The number of wires in the metal layer (N) is a natural number.
(48) The layer wire is inclined with respect to the cable axis, therefore, the surface projected over the circumference that goes through the center of the layer wires is slightly higher than its diameter, d/cos().
(49) The coverage calculation has been defined by the following equation:
(Cov) (%)=N*d/cos()/(3.1416*(Dais+d))*100(3)
(50) The cross section of the layer is calculated as S (mm2) with the following equation:
S(mm2)=N*(d).sup.2*3.1416/4(4)
(51) Considering the volumetric resistivity in (.Math.mm2/km) as the inverse of the electric conductivity, the electrical resistance calculated for the layer R (Q/km) with the following equation:
R(/km)=*S/cos()(5)
(52) Taking into account the density of the aluminum alloybased on the literatureis (kg/dm3), the M (kg/km) conductor mass is calculated based on the following equation:
M(kg/km)=S*density/cos()(6)
(53) The number of wires and the wire diameter are the result of proving by successive approximations, which is the combination that produces the best coverage of about 95-100%, and that is compliant with the electrical resistance requirement.
(54) Finally, the passage of cables from the layer is adjusted to achieve the coverage mentioned above. With a coverage of between 95 y 100%, it allows referring to it as cable to prevent the fraudulent connection to the electric system.
(55) The breaking load is calculated based on the following equation:
T(daN)=S(mm2)*(dan/mm2)*0.9(7)
where
(56) (dan/mm2)=Wire ultimate tensile stress to the traction
(57) The nominal sections are defined for sorting out the different players in the electric sector, the standards define electrical resistance requirements, insulation thicknesses and test voltages, based on nominal sections. The values are verified by excess or defect, as they are defined. For example, the effective section in general fails to match the nominal section. In the cables included in the figures attached, in order to meet the minimum coverage of 95% to ensure anti-fraud functions, the effective section of each layer of wires may be higher than the nominal section. (See Table 1).
(58) Insulating Materials
(59) As insulating materials for the cable types described and mentioned in the figures attached, the following materials may be used: low-density polyethylene (PELD), medium-density polyethylene (PEMD), or high-density polyethylene (PEHD), cross-linked low-density polyethylene (HDXLPE), polypropylene (PP), Polyvinyl chloride-based compounds (PVC), Ethylene-vinyl acetate (EVA)-based compounds, Ethylene propylene rubber-based elastomer compounds (EPR). For medium-voltage they also meet the tracking characteristic.
Preferred Examples
(60)
(61)
(62)
(63)
(64)
(65)
Characteristics of the Preferred Examples
(66) The following examples display-without any limitation-suggested fiber-optic models built with 3.6 mm and 6 mm cables. Volumetric resistivity: 30.5 .Math.mm.sup.2/km (note: a resistivity value has been selected for the design that provides a broad margin of safety to obtain an electrical resistance value according to the standard): electric resistances under IEC 60228 standard for mm.sup.2 sections and ICEA S76-474 for AWG sections.
(67) TABLE-US-00002 TABLE 2 A cable with a central fiber-optic cable of 3.6 mm in diameter and nominal sections in mm.sup.2 Diameter on mm 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 Fiber Optics Nominal mm.sup.2 6 10 16 25 35 50 70 95 120 Section Formation of 19 15 11 9 7 6 6 5 5 1st layer 0.70 0.94 1.42 1.9 2.88 3.9 3.9 5.9 5.9 Passage 14 14 14 14 8.5 14 14 14 14 D D D D D D D d D Formation of 44 47 42 36 38 40 30 34 28 2nd layer 0.56 0.56 0.71 0.97 1.12 1.26 1.74 1.95 2.42 Passage mm 12 11 12 12 12 12 12 12 12 D D D D D D D D D Formation of 64 66 72 70 68 68 54 54 52 3rd layer 0.56 0.56 0.56 0.69 0.86 1.0 1.33 1.64 1.77 Passage mm 10 10.4 8.4 10 10 10 10 10 10 D D D D D D D D D Formation of 72 72 72 72 72 72 72 72 72 4th layer 0.56 0.56 0.6 0.75 0.9 1.05 1.20 1.40 1.50 Passage mm 5 4.5 4.5 5.5 5.5 5.5 7 7 8 D D D D D D D D D Electrical Km 4.61 3.08 1.91 1.2 0.868 0.641 0.443 0.32 0.253 Resistance at 20 C. Thickness of mm 1.2 1.2 1.2 1.4 1.6 1.6 1.8 2.0 2.0 Insulation
(68) TABLE-US-00003 TABLE 3 A cable with a central fiber-optic cable of 6 mm in diameter and nominal sections in mm.sup.2 Diameter on mm 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Fiber Optics Nominal mm.sup.2 6 10 16 25 35 50 70 95 120 Section Formation of 36 30 22 16 12 11 9 8 7 1st layer 0.56 0.69 0.98 1.44 2.09 2.35 3.15 3.93 4.78 Passage 13.5 14 14 14 14 14 14 14 14 D D D D D D D D D Formation of 56 57 56 44 44 36 32 31 29 2nd layer 0.56 0.56 0.61 0.89 1.02 1.35 1.7 2.0 2.33 Passage mm 12 10.5 12 12 12 12 12 12 12 D D D D D D D D D Formation of 72 72 72 72 72 70 56 56 52 3rd layer 0.56 0.56 0.61 0.7 0.82 0.95 1.33 1.51 1.76 Passage mm 6.9 6.1 7.8 7.3 7.8 10.8 10 10 10 D D D D D D D D D Formation of 72 72 72 72 72 72 72 72 72 4th layer 0.56 0.56 0.61 0.75 0.9 1.0 1.20 1.35 1.50 Passage mm 3.5 3.5 3.5 4.5 5 5 7 7 8 D D D D D D D D D Electrical Km 4.61 3.08 1.91 1.2 0.868 0.641 0.443 0.32 0.253 Resistance at 20 C. Thickness of mm 1.2 1.2 1.2 1.4 1.6 1.6 1.8 2.0 2.0 Insulation
(69) TABLE-US-00004 TABLE 4 A cable with a central fiber-optic cable of 3.6 mm in diameter and nominal sections in AWG Diameter on mm 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 Fiber optics Section mm.sup.2 #8 #6 #4 #2 #1/0 #2/0 #3/0 #4/0 section Formation 16 12 9 7 6 6 5 5 1st layer 0.87 1.25 1.9 2.89 3.9 3.9 5.95 5.95 Passage 14 14 14 14 14 14 14 14 D D D D D D D D Formation 46 44 40 38 34 30 36 30 2nd layer 0.56 0.65 0.86 1.12 1.46 1.74 1.83 2.24 Passage mm 12 12 12 12 12 12 12 12 D D D D D D D D Formation 66 71 72 68 60 54 64 54 3rd layer 0.56 0.56 0.65 0.86 1.12 1.33 1.36 1.68 Passage mm 10 10 8.5 10 7.8 10.8 10 10 D D D D D D D D Formation 72 72 72 72 72 72 72 72 4th layer 0.56 0.56 0.7 0.86 1.05 1.16 1.36 1.45 Passage mm 4.5 4 4.5 4.5 6 7 6.5 8 D D D D D D D D Electric Km 3.51 2.21 1.391 0.872 0.551 0.436 0.344 0.274 Resistance a 20 C. Thickness of mm 1.2 1.2 1.4 1.6 1.6 1.8 2.0 2.0 insulation
(70) TABLE-US-00005 TABLE 5 A cable with a central fiber-optic cable of 3.6 mm in diameter and nominal sections in AWG Diameter on mm 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 Fiber optics Section mm.sup.2 #8 #6 #4 #2 #1/0 #2/0 #3/0 #4/0 section Formation 36 24 18 13 10 9 8 7 1st layer 0.56 0.89 1.25 1.89 2.70 3.16 3.81 4.80 Passage 14 14 14 14 14 14 14 14 D D D D D D D D Formation 56 60 46 42 34 32 30 30 2nd layer 0.56 0.56 0.82 1.04 1.46 1.7 2.0 2.25 Passage mm 12 12 12 12 12 11.5 10 12 D D D D D D D D Formation 72 72 72 72 60 60 58 56 3rd layer 0.56 0.56 0.7 0.82 1.12 1.24 1.43 1.62 Passage mm 6.9 5.4 9.5 10 10 10 10 10 D D D D D D D D Formation 72 72 72 72 72 72 72 70 4th layer 0.56 0.65 0.75 0.9 1.05 1.12 1.35 1.50 Passage mm 3.5 4.5 4.5 5 6 7 7 7 D D D D D D D D Electric Km 3.51 2.21 1.391 0.872 0.551 0.436 0.344 0.274 Resistance a 20 C. Thickness of mm 1.2 1.2 1.4 1.6 1.6 1.8 2.0 2.0 Insulation
Cable Installation
(71) In low voltage, the distribution overhead line cable is installed and retained between poles with a walrus determined for its dimensions, ensuring that the cable is fastened and tightened and is not damaged anywhere and maintains its geometric configuration and also the mechanical, electrical and data transmission conditions.
(72) Tensile Test on the Cable Wrapping:
(73) The test was performed with a Bronal, model MAR9 anchoring clamp for ACSR 300/50 mm2 cable, or similar. The wrapping slid inside the anchoring clam at 1500 daN. A dielectric rigidity test of 2.5 kV was performed and the electrical resistance was measured for concentric conductors: the invention cable caused a successful result. This ensures the self-supporting condition without requiring a specific lashing wire outside the active conductive layers and, which have then a double function: as a combined conveyor and as electric power conductors.
(74) On each connection point, the cable must be cut, opening each of its active functions.
(75) Inside the distribution box, the connections required of each element need to be made to ensure a later branch and then a continuity connection to continue with the power and signal distribution towards the next delivery box, if any, based on the given network.
(76) To avoid damage in the box due to mechanical strains at the cable inlet, it has to have the characteristics of flexibility, as a whole, to allow its bending and handling without damaging it, or the components related to the installation function on the distribution network.
(77) On medium voltage, up to 35 kV, the cable is assembled on insulators or hangers. On the retention points the power cable is separated from the fiber optics.
(78) The Fiber Optics is driven to a connection/distribution box.
(79) The metal conductors are spliced with other metal conductors or to the connection bushing of a transformer. The parts exposed are duly insulated.
(80) The cable in this patent supports mechanically the fiber optics to hold and protect it, therefore, it makes the fiber optics inaccessible. The fiber optics may only be accessed by cutting the cable.
(81) In addition to the mechanical protection provided by this configuration, the cable provides electrical protection against intrusion, the concentric conductors are connected to different phases of a power system in low voltage. While the outer conductor is connected to the ground potential, breaking that layer to go to the next inner layer causes a direct short-circuit between phases. A short-circuit in a power system usually causes an explosion, triggering the electrical protections. The activation of protections warns about intrusions.
(82) The cable described in this invention has a fiber-optic cable inside, two or more metal conductors that are insulated between each other and the ground. Each low-voltage conductor cable transmits the current from a phase of the low-voltage power system, and the cable transmits all the low-voltage power system current.
(83) As an additional advantage that solves a long-standing issue, the use of aluminum alloy layers includes 6101 aluminum alloy wire, which has been heat treated by submitting it to a temperature ranging from 260 to 300 C. during 6-8 hours help such concentric (layer) multi-conductors avoid stretching, thus allowing to insert the fiber optics without breaking it.
Glossary
(84) Multi-fiber fiber-optic cable: An optical fiber cable containing fiber optics. The fiber optics are gathered inside container tubes. The tubes containing the fiber optics are wired on a dielectric bearing element. A synthetic material covering is applied to the set of tubes.
(85) Lashing wire: a wire or cord used as a mechanical support for an overhead cable. The lashing wire is tightened between 2 fixed points. It may be an electrical conductor. It may be bare or insulated.
(86) Anti-tracking: A property of the synthetic compound material to resist surface electric discharges.
(87) Insulators for overhead lines: a power overhead line accessory that allows fastening a low-voltage cable by means of a stemming or by compression. The insulator prevents electric discharges to the ground in normal operation conditions.
(88) Aluminum alloy: a chemical composition where the aluminum is the prevailing element.
(89) Anti-fraud connection: a cable of a specific built which makes it more difficult to connect conductors under voltage, for avoiding unregistered electrical connections.
(90) Concentric conductor: a closed layer of copper or aluminum wires and their alloys around an insulated conductor or set of conductors.
(91) Medium-voltage protected cable: an insulated overhead cable, which being live is resistant to contacts with grounded elements for short periods of time. High voltage may be measured on the cable surface. For electrical safety reasons, the permanent contact with persons and animals with live cables is not allowed. It avoids electric shocks in case of accidental contact with a live cable.
(92) Connection box and/or cabinet: a plastic or metal cabinet, with the following elements inside: fiber-optic cables, signal conductors, low-voltage electric power conductors, devices for handling and control of networks. They provide electrical safety to the public in general, and protect the elements inside of it from external influences.
(93) Wooden or concrete poles: are used in overhead cable networks to install signal, telephone, power lines outside the reach of the public in general. The cables are fastened with accessories, 1/10 of their length is recessed in the ground in a suitable foundation. They are characterized by the height and stress they can support without breaking on their upper end.
(94) Insulation: an arrangement of a material separating a live element or part from another conductive element.
(95) Self-supporting: an element supporting its own weight is its movable condition or in a static situation and needs no foreign element to stand the wiring and installation conditions.
(96) Coverage: a copper and aluminum-and their alloy-material arrangement covering fully or partially the surface where they are arranged in a circular section cable.
(97) Metal wire: a copper and aluminum-and their alloy-conductor obtained from drawing usually with a circular section with a diameter lower than 5.95 mm.
(98) Drawing process: the stretching of wire in cold, successive steps by the use of diamond or tungsten carbide dies or draws whose diameter is gradually lower. Such a section decrease provides the material with certain temper thus benefiting its mechanical characteristics (temper: is the property of a metal that is translated into an increase in its hardness, fragility and tensile strength as a result of cold deformations). In wires, reductions of up to 90% can be obtained after successive passages, starting from annealed material and before a new annealing process is required for eliminating temper. The advantages provided by cold wire drawing are the following: good surface quality, dimensional accuracy, increase in resistance and hardness, and, of course, the possibility of producing very thin sections.
(99) Rolling: Rolling is an industrial process whereby a metal sheet thickness is reduced or similar material, applying pressure by the use of different processes, such as ring-rolling or the rolling of profiles. Therefore, this process is applied to material with a good level of malleability. The equipment used for this process is known as roller
(100) Residential connection: An electrical connection by means of insulated conductor cables which supply electric power from a distribution network to certain premises at a certain point of delivery inside the place or building (connection point).
(101) Layer of protection: Sequence of points consecutively joined around a circumference, represented by the cross-section of copper and aluminum-and their alloys-wire installed in a sequential manner, such that they complete a circumference, leaving no space between one point and the other, one next to the other.
(102) Low-voltage electric distribution: electric power distribution service supplied by means of conductor cables arranged as main branches starting from a power transformation center, forming a network. From such distribution network cables, residential connections are made for voltage rates lower than 1 kV.
(103) Creep effect: Permanent elongation of cables due to mechanical stresses supported on a daily basis.
(104) Nominal section: Name given by the standard to a certain electrical section. Its value is not limitative but it is used as reference. The specific values to be met are defined in each particular standard.