METHOD FOR ASSEMBLING AN ELECTRICAL CABLE WITH REDUCED SKIN EFFECT AND CORRESPONDING ELECTRICAL CABLE

Abstract

An electrical cable has a cross section with an area of predetermined dimension. The cable is formed by a plurality of conductors electrically insulated from one another. A plurality of first bundles, each having at least three conductors, is formed (10), and, as long as the predetermined dimension is not reached, a plurality of (n+1).sup.th bundles each having at least three of the n.sup.th bundles, n being an integer greater than or equal to 1, is iteratively formed (14).

Claims

1. Method for assembling an electrical cable whose cross section has an area of predetermined dimension, said cable being formed by a plurality of conductors electrically insulated from one another, said method comprising the steps of: forming a plurality of first bundles each comprising at least three conductors; and as long as said predetermined dimension is not reached, iteratively forming a plurality of (n+1).sup.th bundles each comprising at least three of the n.sup.th bundles, n being an integer greater than or equal to 1.

2. Method according to claim 1, wherein said at least three conductors of said first bundles are disposed such that the central points of their cross sections are on one and the same circle and said at least three n.sup.th bundles are disposed such that the central points of their cross sections are on one and the same circle.

3. Method according to claim 1, wherein each of said first bundles comprises between three and five conductors.

4. Method according to claim 1, wherein, for each value of said integer n, each of said (n+1).sup.th bundles comprises between three and five of said n.sup.th bundles.

5. Method according to claim 1, wherein said integer n takes, successively, the values 1 to 3.

6. Method according to claim 1, wherein said conductors are made of aluminium.

7. Electrical cable formed by a plurality of conductors electrically insulated from one another, wherein said electrical cable is obtained by the implementation of an assembly method according to claim 1.

8. Electrical cable according to claim 1, wherein said electrical cable is an aeronautical cable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other aspects and advantages of the invention will emerge on reading the following detailed description of particular embodiments, given as nonlimiting examples, with reference to the attached drawings, in which:

[0034] FIG. 1 is a flow diagram illustrating steps of a method of assembling an electrical cable according to the present invention, in a particular embodiment;

[0035] FIG. 2 is a schematic representation of the cross section of first bundles of conductors assembled according to an assembly method according to the present invention, in particular embodiments;

[0036] FIG. 3 is a schematic representation of the cross section of second bundles of conductors assembled according to an assembly method according to the present invention, in particular embodiments; and

[0037] FIG. 4 is a schematic representation of the cross section of third bundles of conductors assembled according to an assembly method according to the present invention, in particular embodiments.

DETAILED DESCRIPTION

[0038] In the context of the present invention, an electrical cable is considered that has a cross section with a predetermined area. This cable is formed by several conductors. These conductors are electrically insulated from one another.

[0039] The cable can for example be an aeronautical cable, used for example onboard an aeroplane.

[0040] The electrical insulation of the conductors can be produced by any means. It is advantageously obtained naturally when the conductors are made of aluminium, because a layer of aluminium oxide, electrically insulating, is naturally formed on the surface of such conductors.

[0041] As the flow diagram of FIG. 1 shows, the method, according to the invention, of assembling an electrical cable formed by several conductors electrically insulated from one another comprises a first step 10 consisting in forming several first bundles of conductors.

[0042] In a particular embodiment, each first bundle comprises at least three conductors.

[0043] Advantageously, each first bundle comprises between three and five conductors.

[0044] The conductors are held together in each bundle by simple twist effect, without it being necessary to provide any particular fixing means between the conductors.

[0045] FIG. 2 illustrates the cross section of a first bundle of conductors 20 in three different exemplary embodiments: from left to right, there are represented a first example in which the first bundle F1 comprises three conductors 20, a second example in which the first bundle F1 comprises four conductors 20 and a third example in which the first bundle F1 comprises five conductors 20.

[0046] In these three exemplary embodiments, the conductors 20 of each first bundle F1 or F1 or F1 are disposed such that the central points of the cross section of these conductors 20 are situated on one and the same circle. This disposition is particularly advantageous because it allows each conductor 20 to occupy successively, as it progresses along the axis of the cable, at least a part of all of the points of the cross section of this cable, even all the points of the cross section of the cable if the length of the cable is sufficient for that.

[0047] Thus, at high frequency, the skin effect will occur only within a conductor 20. The current will thus circulate in all the conductors 20 and will not be confined to the surface of the cable.

[0048] At the end of the step 10 of formation of the first bundles F1 or F1 or F1 of conductors 20, in a test 12, a determination is made as to whether the area of the cross section of the cable has reached the desired dimension.

[0049] If such is the case, the cable assembly method is terminated.

[0050] Otherwise, in the next step 14, second bundles of conductors 20, each comprising at least three first bundles, are formed. The first bundles used to form a second bundle advantageously all have the same number of conductors 20.

[0051] FIG. 3 illustrates the cross section of a second bundle of conductors 20 in three different exemplary embodiments: from left to right, there are represented a first example in which the second bundle F2 comprises three first bundles F1 each comprising three conductors 20, a second example in which the second bundle F2 comprises four first bundles F1 each comprising five conductors 20 and a third example in which the second bundle F2 comprises five first bundles F1 each comprising four conductors 20.

[0052] In these three exemplary embodiments, the first bundles included in each second bundle F2 or F2 or F2 are disposed such that none of the first bundles is located at the centre of the second bundle. That amounts to having the central points of the cross sections of the first bundles situated on one and the same circle. This disposition is particularly advantageous because it allows each conductor 20 to occupy, successively as it progresses along the axis of the cable, at least a part of all the points of the cross section of this cable, even all the points of the cross section of the cable if the length of the cable is sufficient for that.

[0053] As at the end of the step 10 of formation of the first bundles, in the test 12, at the end of the step 14 of formation of the second bundles, a test is carried out as to whether the dimension desired for the area of the cross section of cable formed by the second bundles has been reached.

[0054] If such is the case, the cable assembly method is terminated.

[0055] Otherwise, the iteration consisting in forming, in step 14, (n+1).sup.th bundles each comprising at least three n.sup.th bundles, n being an integer greater than or equal to 1, is continued.

[0056] Advantageously, for each value of the integer n, each of the (n+1).sup.th bundles comprises between three and five n.sup.th bundles.

[0057] Thus, FIG. 4 illustrates the cross section of a third bundle of conductors 20 in two different exemplary embodiments: from left to right, there are represented a first example in which the third bundle F3 comprises three second bundles F2 each comprising four first bundles F1 of five conductors 20 and a second example in which the third bundle F3 comprises four second bundles F2 each comprising five first bundles F1 of four conductors 20.

[0058] In these two exemplary embodiments, the second bundles of each third bundle F3 or F3 are disposed such that none of the second bundles is located at the centre of the third bundle. That amounts to having the central points of the cross sections of the second bundles situated on one and the same circle. This disposition is particularly advantageous because it allows each conductor 20 to occupy, successively as it progresses along the axis of the cable, at least a part of all the points of the cross section of this cable, even all the points of the cross section of the cable if the length of the cable is sufficient for that.

[0059] As a nonlimiting example, the integer n can take, successively, the values 1 to 3. Thus, in an example in which the first bundles each comprise 4 conductors (like the bundle F1), the second bundles each comprise 4 first bundles (like the bundle F2), the third bundles each comprise 4 second bundles and the fourth bundles each comprise 4 third bundles, the cable is formed by the assembly of [4(4(4(44)]=1024 conductors.

[0060] Conventional aluminium cables are generally formed by conductors of 0.37 mm diameter. This diameter has been chosen as a good trade-off between flexibility and complexity of the cable and is also sufficiently small to make it possible to avoid an increase in the resistance due to the skin effect at the frequencies concerned.

[0061] The cross sections of cable required to withstand high currents lie between AWG00 and AWG0000. A conventional AWG000 cable is an assembly of 19 concentric bundles, each bundle being composed of 44 conductors of 0.37 mm diameter, i.e. 836 conductors in total.

[0062] In the abovementioned example of the invention with a cable with reduced skin effect comprising [4(4(4(44)]=1024 conductors assembled according to the method of the invention, the diameter of the conductors can be reduced to 0.334 mm.

[0063] Another nonlimiting example consists in assembling [4(4(4(34)]=768 conductors according to the invention. In this other example, the diameter of the conductors ought to be increased to 0.39 mm.

[0064] Measurement makes it possible to confirm that, whereas for an AWG000 cable, the increase in the resistance is 45% (compared to the direct current resistance) at a frequency of 1 kHz, the increase in resistance for an AWG000 cable assembled according to the present invention is negligible for frequencies ranging up to 5 kHz. The resistance of an AWG000 cable according to the invention is therefore 45% lower than that of a conventional AWG000 cable.