Abstract:
A stranded electrical conductor includes a single center strand in aluminum or aluminum alloy ( 10, 20, 30, 40 A,  50 A) and a plurality of conductor strands ( 11, 21, 31, 41, 51 ) arranged in at least one layer around said center strand. The relation between the diameter of said center strand in aluminum or aluminum alloy and the diameter of said peripheral conductor strands is greater than or equal to 3.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of priority from French Patent Application No. 15 62065, filed on Dec. 9, 2015, the entirety of which is incorporated by reference. 
       BACKGROUND 
       [0002]    Field of the Invention 
         [0003]    The invention relates to an electrical conductor for aeronautical applications. 
         [0004]    Description of the Related Art 
         [0005]    Patent document FR 3 009 126 describes such a stranded electrical conductor comprising at least one center strand in silver-plated aluminum and a plurality of silver-plated copper strands arranged around said center strand. 
         [0006]    More precisely, said document describes a first conductor comprising one aluminum strand arranged in the center of the conductor, surrounded by six peripheral copper strands in contact two-by-two and arranged in a single layer. 
         [0007]    It also describes a second conductor comprising seven aluminum strands arranged in the center of the conductor, namely one center strand surrounded by six strands, said seven strands being surrounded by twelve peripheral copper strands in contact two-by-two and arranged in a single layer. 
         [0008]    It finally describes a third conductor comprising nineteen aluminum strands arranged in the center of the conductor, namely one center strand surrounded by six strands, surrounded by twelve strands, said nineteen strands being surrounded by eighteen peripheral copper strands in contact two-by-two and arranged in a single layer. 
         [0009]    According to all the described embodiments, the diameter of the center aluminum strands is substantially equal to that of the peripheral copper strands. 
         [0010]    Assembly cohesion of the strands is obtained by means of an assembly operation, commonly known as stranding, and which makes it possible, by twisting and according to a preferred pitch value, to maintain the relative position of each strand in relation to the others. 
         [0011]    The aluminum strands are therefore of a smaller diameter and their assembly by stranding is difficult on account of the fragility of said strands. 
         [0012]    Furthermore, a stranded electrical conductor is known from Patent document WO 2012/073843, comprising a single center strand possibly in aluminum or aluminum alloy and a plurality of conductor strands arranged in at least one layer around said center strand. 
       OBJECTS AND SUMMARY 
       [0013]    Without compromising the flexibility of the conductor, the invention proposes to reduce the use of aluminum strands with such a small cross section. 
         [0014]    To do this, the invention proposes a stranded electrical conductor comprising a single center strand in aluminum or aluminum alloy and a plurality of conductor strands arranged in at least one layer around said center strand, wherein the relation between the diameter of said center strand in aluminum or aluminum alloy and the diameter of the peripheral conductor strands is greater than or equal to 3. 
         [0015]    According to a preferred embodiment, the relation between the diameter of said center strand in aluminum or aluminum alloy and the diameter of the peripheral conductor strands is between 3 and 5. 
         [0016]    The diameter of all said peripheral conductor strands is preferably substantially identical. 
         [0017]    Furthermore, the size known as American Wire Gauge (acronym AWG, also known by the name Brown and Sharp (B&amp;S) Wire Gauge) is a unit of measurement used in the United States among others, allowing the diameter of a single-strand non-ferrous metal conductor to be measured and standardized. Said size is defined by the following data: 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
               
               
                 AWG 
                 Diameter (mm) 
                 Cross-section (mm 2 ) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 12 
                 2.05 
                 3.31 
               
               
                 13 
                 1.83 
                 2.62 
               
               
                 14 
                 1.63 
                 2.08 
               
               
                 15 
                 1.45 
                 1.65 
               
               
                 16 
                 1.29 
                 1.31 
               
               
                 17 
                 1.15 
                 1.04 
               
               
                 18 
                 1.02 
                 0.823 
               
               
                 19 
                 0.912 
                 0.653 
               
               
                 20 
                 0.812 
                 0.518 
               
               
                 21 
                 0.723 
                 0.410 
               
               
                 22 
                 0.644 
                 0.326 
               
               
                 23 
                 0.573 
                 0.258 
               
               
                 24 
                 0.511 
                 0.205 
               
               
                 25 
                 0.455 
                 0.162 
               
               
                 26 
                 0.405 
                 0.129 
               
               
                 27 
                 0.361 
                 0.102 
               
               
                 28 
                 0.321 
                 0.0810 
               
               
                 29 
                 0.286 
                 0.0642 
               
               
                 30 
                 0.255 
                 0.0509 
               
               
                   
               
             
          
         
       
     
         [0018]    Said size is also used to describe conductors with several stranded wires. In this case, it refers to a conductor whose transverse cross section is equal to the sum of the transverse cross sections of the individual wires, the space between individual wires not being considered. 
         [0019]    According to an embodiment of the invention, the conductor being AWG between 16 and 30, comprising a single center strand in aluminum or aluminum alloy and a plurality of conductor strands arranged around said center strand, the relation between the diameter of said strand in aluminum or aluminum alloy and the diameter of said peripheral conductor strands is 3, said peripheral conductor strands being in contact two-by-two and twelve in number. 
         [0020]    Advantageously, said conductor strands are in copper or copper alloy. They can also be hybrid, comprising, for example, an aluminum part and a copper part. 
         [0021]    At least one of said conductor strands preferably consists of at least one layer of copper and one layer of silver-plated copper alloy, whose mass ratio of silver is between 0.1% and 0.5%. 
         [0022]    The mass ratio represents the relation between the mass of silver and the mass of silver-plated copper alloy. The specific contribution of each strand consisting of a layer in copper and a layer of silver-plated copper alloy, whose mass ratio of silver is between 0.1% and 0.5%, is that it allows the conductor to have greater mechanical strength than that of a copper strand of an equivalent cross-section, without degrading electric conductivity. The conductor can possess either a single strand or several strands of such a composition. Said conductor can also comprise other conductor strands consisting of different compositions. 
         [0023]    Strands arranged on the periphery of the conductor and consisting of at least one layer of copper and one layer of silver-plated copper alloy make it possible to minimize contact resistances consecutive to the connection of connection components by the user. 
         [0024]    The strands are advantageously coated with a protective layer vis-à-vis corrosion. 
         [0025]    Mechanical strains, variations of temperature, hygrometry and pressure, together with insulating materials, in effect impose on conductors and hence on the constituent strands of said conductors, a specific adaptation vis-à-vis the risks of corrosion. 
         [0026]    The protective layer can be a layer of nickel. 
         [0027]    The invention also relates to an electric cable consisting of at least such a conductor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention is described below in more detail with the help of the figures, showing only preferred embodiments of the invention. 
           [0029]      FIG. 1  is a view in transverse section of a first embodiment of the invention. 
           [0030]      FIG. 2  is a view in transverse section of a second embodiment of the invention. 
           [0031]      FIG. 3  is a view in transverse section of a third embodiment of the invention. 
           [0032]      FIG. 4  is a view in transverse section of a fourth embodiment of the invention. 
           [0033]      FIG. 5  is a view in transverse section of a fifth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]    The conductor shown on  FIG. 1  is AWG between 16 and 30 and comprises a single center strand  10  in aluminum or aluminum alloy and a plurality of strands  11  in copper or copper alloy arranged around said center strand. The relation between the diameter of the strand in aluminum or aluminum alloy and the diameter of the peripheral strands in copper or copper alloy is 3, said peripheral strands in copper or copper alloy being in contact two-by-two and twelve in number. The relation between the cross section of the strand in aluminum or aluminum alloy and the cross section of the peripheral strands in copper or copper alloy is 43%. 
         [0035]    More precisely, the characteristics of the strands according to AWG are specified in table 1 below. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Al/Al alloy strands 
                 Cu/Cu alloy strands 
               
             
          
           
               
                   
                   
                 Wire Ø 
                 Cross section 
                   
                 Wire Ø 
                 Cross section 
               
               
                 AWG 
                 Number 
                 mm 
                 mm 2   
                 Number 
                 mm 
                 mm 2   
               
               
                   
               
             
          
           
               
                 30 
                 1 
                 0.191 
                 0.029 
                 12 
                 0.0635 
                 0.038 
               
               
                 28 
                 1 
                 0.236 
                 0.044 
                 12 
                 0.0785 
                 0.058 
               
               
                 26 
                 1 
                 0.3 
                 0.071 
                 12 
                 0.1 
                 0.094 
               
               
                 24 
                 1 
                 0.345 
                 0.093 
                 12 
                 0.115 
                 0.125 
               
               
                 22 
                 1 
                 0.48 
                 0.181 
                 12 
                 0.16 
                 0.241 
               
               
                 20 
                 1 
                 0.609 
                 0.291 
                 12 
                 0.203 
                 0.388 
               
               
                 18 
                 1 
                 0.762 
                 0.456 
                 12 
                 0.254 
                 0.608 
               
               
                 16 
                 1 
                 0.9 
                 0.636 
                 12 
                 0.3 
                 0.848 
               
               
                   
               
             
          
         
       
     
         [0036]    The conductor shown on  FIG. 2  is AWG  12  or  14  and comprises a single center strand  21  in aluminum or aluminum alloy and a plurality of strands  22  in copper or copper alloy arranged around said center strand. The relation between the diameter of the strand in aluminum or aluminum alloy and the diameter of the peripheral strands in copper or copper alloy is  5 , said peripheral strands in copper or copper alloy being in contact two-by-two and eighteen in number. The relation between the cross section of the strand in aluminum or aluminum alloy and the cross section of the peripheral strands in copper or copper alloy is 58%. 
         [0037]    More precisely, the characteristics of the strands according to AWG are specified in table 2 below. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 Al/Al alloy strands 
                 Cu/Cu alloy strands 
               
             
          
           
               
                   
                   
                 Wire Ø 
                 Cross section 
                   
                 Wire Ø 
                 Cross section 
               
               
                 AWG 
                 Number 
                 mm 
                 mm 2   
                 Number 
                 mm 
                 mm 2   
               
               
                   
               
               
                 14 
                 1 
                 1.250 
                 1.227 
                 18 
                 0.25 
                 0.884 
               
               
                 12 
                 1 
                 1.600 
                 2.011 
                 18 
                 0.32 
                 1.448 
               
               
                   
               
             
          
         
       
     
         [0038]    The conductor shown on  FIG. 3  is AWG  12  or  14  and comprises a single center strand  30  in aluminum or aluminum alloy and a plurality of strands  31  in copper or copper alloy arranged around said center strand. The relation between the diameter of the strand in aluminum or aluminum alloy and the diameter of the peripheral strands in copper or copper alloy is  3 , said peripheral strands in copper or copper alloy being in contact two-by-two and arranged in two layers of twelve and eighteen strands. The relation between the cross section of the strand in aluminum or aluminum alloy and the cross section of the peripheral strands in copper or copper alloy is 23%. 
         [0039]    More precisely, the characteristics of the strands according to AWG are specified in table 3 below. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
             
               
                   
                 Al/Al alloy strands 
               
             
          
           
               
                   
                   
                   
                 Wire Ø 
                 Cross section 
               
               
                   
                 AWG 
                 Number 
                 mm 
                 mm 2   
               
               
                   
                   
               
               
                   
                 14 
                 1 
                 0.750 
                 0.442 
               
               
                   
                 12 
                 1 
                 0.960 
                 0.724 
               
               
                   
                   
               
             
          
           
               
                   
                 Cu/Cu alloy strands 
               
             
          
           
               
                   
                 Number 
                 Wire Ø 
                 Cross section 
                 Number 
                 Wire Ø 
                 Cross section 
               
               
                 AWG 
                 Layer 1 
                 mm 
                 mm 2   
                 Layer 2 
                 mm 
                 mm 2   
               
               
                   
               
               
                 14 
                 12 
                 0.250 
                 0.589 
                 18 
                 0.25 
                 0.884 
               
               
                 12 
                 12 
                 0.320 
                 0.965 
                 18 
                 0.32 
                 1.448 
               
               
                   
               
             
          
         
       
     
         [0040]    The conductor shown on  FIG. 4  is AWG  12  or  14  and comprises a layer of six strands  40 B in aluminum on a center strand  40 A and a plurality of strands in copper or copper alloy arranged in a single layer around said center strands. The relation between the diameter of the strands in aluminum or aluminum alloy and the diameter of the peripheral strands in copper or copper alloy is 1.67, said peripheral strands in copper or copper alloy being in contact two-by-two and eighteen in number. The relation between the cross section of the strands in aluminum or aluminum alloy and the cross section of the peripheral strands in copper or copper alloy is 52%. 
         [0041]    More precisely, the characteristics of the strands according to AWG are specified in table 4 below. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 4 
               
               
                   
                   
               
             
             
               
                   
                 Al/Al alloy strands 
               
             
          
           
               
                   
                 Number 
                 Wire Ø 
                 Cross section 
                 Number 
                 Wire Ø 
                 Cross section 
               
               
                 AWG 
                 Core 
                 mm 
                 mm 2   
                 Layer 1 
                 mm 
                 mm 2   
               
               
                   
               
               
                 14 
                 1 
                 0.417 
                 0.136 
                 6 
                 0.417 
                 0.818 
               
               
                 12 
                 1 
                 0.533 
                 0.223 
                 6 
                 0.533 
                 1.340 
               
               
                   
               
             
          
           
               
                   
                 Cu/Cu alloy strands 
               
             
          
           
               
                   
                   
                   
                 Wire Ø 
                 Cross section 
               
               
                   
                 AWG 
                 Number 
                 mm 
                 mm 2   
               
               
                   
                   
               
               
                   
                 14 
                 18 
                 0.25 
                 0.884 
               
               
                   
                 12 
                 18 
                 0.32 
                 1.448 
               
               
                   
                   
               
             
          
         
       
     
         [0042]    The conductor shown on  FIG. 5  is AWG  12  or  14  and comprises a layer of twelve strands  50 B in aluminum on the center strand  50 A and a plurality of strands  51  in copper or copper alloy arranged in a single layer around said center strands. The relation between the diameter of the center strand  50 A in aluminum or aluminum alloy and the diameter of the peripheral strands in copper or copper alloy is 3, said peripheral strands in copper or copper alloy being in contact two-by-two and eighteen in number. 
         [0043]    The relation between the cross section of the strands in aluminum or aluminum alloy  50 A and  50 B in aluminum or aluminum alloy and the cross section of the peripheral strands in copper or copper alloy is 54%. As for the relation between diameter of the center strand  50 A in aluminum or aluminum alloy and the diameter of the layer of strands in aluminum or aluminum alloy surrounding it, it is also 3. 
         [0044]    More precisely, the characteristics of the strands according to AWG are specified in table 5 below. 
         [0000]    
       
         
               
               
             
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 5 
               
               
                   
                   
               
             
             
               
                   
                 Al/Al alloy strands 
               
             
          
           
               
                   
                 Number 
                 Wire Ø 
                 Cross section 
                 Number 
                 Wire Ø 
                 Cross section 
               
               
                 AWG 
                 Core 
                 mm 
                 mm 2   
                 Layer 1 
                 mm 
                 mm 2   
               
               
                   
               
               
                 14 
                 1 
                 0.750 
                 0.442 
                 12 
                 0.250 
                 0.589 
               
               
                 12 
                 1 
                 0.960 
                 0.724 
                 12 
                 0.320 
                 0.965 
               
               
                   
               
             
          
           
               
                   
                 Cu/Cu alloy strands 
               
             
          
           
               
                   
                   
                   
                 Wire Ø 
                 Cross section 
               
               
                   
                 AWG 
                 Number 
                 mm 
                 mm 2   
               
               
                   
                   
               
               
                   
                 14 
                 18 
                 0.25 
                 0.884 
               
               
                   
                 12 
                 18 
                 0.32 
                 1.448 
               
               
                   
                   
               
             
          
         
       
     
         [0045]    In every case, the conductor strands are arranged together such that the circular cross section of the conductor is as circular as possible. In effect, such a conductor is easy to handle. Furthermore, its flexing behavior is identical, whatever the direction of flexion. It is therefore easier to deploy and connect in order to make an electrical connection between different devices.