Technical field

[0001] The present invention relates generally to electrical conductors and cables. More specifically, it relates to methods for manufacturing conductors and cables that radiate a low electromagnetic field.

Background art

[0002] Electrical conductors come in many different forms. Typically, it is the intended use of the conductor that determines the design of an electrical conductor. Some conductors are designed for power distribution, others are designed for transmission of signals such as telecommunications signals as well as for other purposes. Furthermore, electrical conductors can be manufactured from wires of different materials such as copper, aluminum, steel or nickel. Typically, two or more conductors are joined to form a cable.

[0003] An electrical current running through a conductor causes it to radiate an electromagnetic field. This electromagnetic field can negatively affect equipment or other conductors in the proximity of the conductor, which can limit for example how closely together conductors or cables can be arranged. Therefore, regardless of the type of conductor, it is typically desired that the radiated electromagnetic field is low. Often, this is achieved by providing shielding components which surround the entire length of the conductor.

[0004] An alternative to providing shielding components is disclosed in US Patent 9,953,737. The patent discloses a conductor and a cable having an aluminum core surrounded by copper wires which has the effect of reducing the electromagnetic field.

[0005] Commonly, standardized dimensions of electrical conductors are used. But with the fast evolution of technology, conductors may need completely different dimensions, than those that are industry standard today. It remains to be solved how to obtain a conductor emitting a low electromagnetic field at any given dimension of the conductor. [0006] Therefore, there is still a need for a method for providing an electrical conductor which displays a reduction of the electromagnetic field to a desired level at any given dimension of the conductor.

Summary of invention

[0007] It is an object of the invention to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by providing a method for manufacturing an electrical conductor and a method for manufacturing a cable comprising such conductors, which display a desired reduction of the electromagnetic field at any given dimension of the conductor according to the present invention.

[0008] The invention is based on the insight, that the electromagnetic field can be reduced to a desired amount for a given dimension of a conductor when a relation between cross-sectional areas of aluminum and copper is a relation specified for that given dimension. When reference is made to the dimension of the conductor, it should be understood as the cross-sectional area of the conductor, which is essentially equal throughout the length of the conductor.

[0009] According to the invention, there is provided a method for manufacturing a conductor comprising the steps of choosing a desired dimension D of the conductor, determining a first percentage Pi and a second percentage P2 of a respective first and second component of the conductor and assembling the first and second components corresponding to the determined first and second percentages into a conductor having the chosen dimension D, characterized in that that determining the first percentage P1 and second percentage P2 comprises making two consecutive calculations according to a first and a second formulation: Pi = 12.20 - D * 12.20/75, P ₂ = 100 - Pi.

[0010] The technical effect provided by a method according to the invention is that the percentage of each component can be calculated based on a desired dimension of the manufactured conductor. Having a combination of a certain dimension with its corresponding calculated percentages of each component, causes the manufactured conductor to emit a reduced electromagnetic field, compared to having other percentages of each component combined with that desired dimension. [0011 ] In an exemplary embodiment of the invention, the first component is aluminum wire and the second component is copper wire.

[0012] In an exemplary embodiment of the invention, the first percentage and the second percentage are percentages of the cross-sectional area of the conductor.

[0013] In an exemplary embodiment of the invention, wherein the dimension D corresponds to the cross-sectional area of the conductor.

[0014] In an exemplary embodiment of the invention, the first component is one single aluminum wire and second component is a plurality of copper wires.

[0015] In an exemplary embodiment of the invention, the aluminum wire is a central wire surrounded by the plurality of copper wires.

[0016] In an exemplary embodiment of the invention, the first and second percentages include a tolerance of ±0.1 %.

[0017] According to the invention, there is also provided a method for manufacturing a cable comprising the steps of providing at least one conductor manufactured according to any of the exemplary embodiments, providing the at least one conductor with at least one of a jacket, a filling material, a binder and a coating.

[0018] According to the invention, there is also provided a conductor manufactured according to the exemplary embodiments.

[0019] According to the invention, there is also provided a cable manufactured according to the exemplary embodiments.

Brief description of drawings

[0020] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 shows a conductor comprised by aluminum and copper wires.

Fig. 2 shows a cable with two conductors.

Fig. 3 shows a cable with one conductor. Description of embodiments

[0021] In the following, a detailed description of a method for manufacturing a conductor and cable is disclosed.

In Fig 1 , a cross-sectional view of an electrical conductor 1 in accordance with a first embodiment is shown. A conductor is defined as an assembly of a plurality of conducting wires, and a wire is defined as a single conducting metal thread. The electrical conductor 1 has a central core comprising an aluminum wire 11. Surrounding the central core comprising the aluminum wire 11 , one or more copper wires 12 are provided. Further, the electrical conductor 1 has a dimension D which can be any desired dimension that is suitable for the intended use of the conductor. The dimension D corresponds to the cross-sectional area of the conductor, which in turn is given by the sum of the cross-sectional areas of the aluminum wire 11 and the copper wires 12. Surprisingly, it has been found that the magnitude of the electromagnetic field radiated from the electrical conductor 1 depends on what area percentage of the dimension D comprises the aluminum wire 11 and what area percentage comprises the copper wires 12. Furthermore, it has been found that it is possible to achieve a greater reduction of the electromagnetic field from the conductor 1 using certain relations between the area percentages of aluminum wire 11 and copper wires 12, compared to others. Even more surprisingly, it has been found that for a given dimension D there are corresponding relations between the area percentages which most sufficiently reduce the electromagnetic field for that given dimension.

A first and a second formulation are therefore provided which allow a first and a second cross-sectional area percentage to be calculated. The first percentage corresponds to the area of the aluminum wire 11 and the second percentage corresponds to the sum of the areas of the copper wires 12. For a given dimension, the first and second formulations can be used to calculate a first and a second area percentage which to a desired extent reduces the electromagnetic field radiated from the electrical conductor 1 having that given dimension.

Since the electrical conductor 1 only comprises the aluminum wire 11 and copper wires 12, the first and second area percentages have a sum equal to 100%. Naturally, for a given length of the conductor, the area percentages also represent the volume percentages of the aluminum wire 11 and the copper wires 12.

The first formulation results in the first percentage, PAI, namely the area percentage of aluminum wire 11. It is calculated by firstly determining a desired dimension D for the conductor 1 and subsequently making a calculation according to the first formulation:

1 2 2n

P _A

^A _l L = 12.20 - (D * - * 0.75 1 h00)·

[0022]The second formulation results in the second percentage, Pcu, namely the area percentage of the copper wires 12. This is the remaining area of the dimension D up to 100%, and is thus obtained by subtracting the first percentage from 100%:

P cu 100 PAI -

[0023]Following are some examples where the first and second formulations are employed. The examples should not be seen as limiting to the scope of the invention.

Example 1: D = 1.0 mm ²

[0024] An electrical conductor 1 with a dimension D of 1 mm ² is desired. Furthermore, a low electromagnetic field radiated from the electrical conductor 1 is desired. In order to reduce the electromagnetic field to a desired extent, a relation between the cross-sectional area percentage of the aluminum wire 11 and the copper wires 12 is sought. The percentage of the aluminum wire 11 is calculated through the first formulation:

[0025] P _Al = 12.20 12.04

V 0.75 100/

[0026] The obtained percentage 12.04 % aluminum. The remaining area of the dimension D is calculated through the second formulation:

[0027] P _Cu = 100 - 12.04 = 87.96 [0028] The obtained percentage is 87.96 % copper.

[0029] The relation is thus 12.04 % of the aluminum wire 11 and 87.96 % of the copper wires 12.

Example 2: D = 2.5 mm ²

[0030] An electrical conductor 1 with a dimension D of 2.5 mm ² is desired. Furthermore, a low electromagnetic field radiated from the electrical conductor 1 is desired. In order to reduce the electromagnetic field to a desired extent, a relation between the cross-sectional area percentage of the aluminum wire 11 and the copper wires 12 is sought. The percentage of the aluminum wire 11 is calculated through the first formulation:

[0031] P _Al = 12.20 . 11.79

V 0.75 100/

[0032] The obtained percentage 11.79 % aluminum. The remaining area of the dimension D is calculated through the second formulation:

[0033] P _Cu = 100 - 11.79 = 88.21

[0034] The obtained percentage is 88.21 % copper.

[0035] The relation is thus 11.79 % of the aluminum wire 11 and 88.21 % of the copper wires 12.

Example 3: D = 16.0 mm ²

[0036] An electrical conductor 1 with a dimension D of 16 mm ² is desired. Furthermore, a low electromagnetic field radiated from the electrical conductor 1 is desired. In order to reduce the electromagnetic field to a desired extent, a relation between the cross-sectional area percentage of the aluminum wire 11 and the copper wires 12 is sought. The percentage of the aluminum wire 11 is calculated through the first formulation:

[0037] P _Al = 12.20 9.06

V 0.75 100/ [0038] The obtained percentage is 9.06 % aluminum. The remaining area of the dimension D is calculated through the second formulation:

[0039] P _Cu = 100 9.06 91.40

[0040] The obtained percentage is 91.40 % copper.

[0041] The relation is thus 9.06 % of the aluminum wire 11 and 91.40 % of the copper wires 12.

Manufacturing method

[0042] The invention relates to a method for manufacturing the electrical conductor. The method comprises four steps:

1. Determining a desired dimension D,

2. Making a calculation according to the first formulation,

3. Making a calculation according to the second formulation,

4. Assembling an electrical conductor 1 having the desired dimension D and comprising the aluminum wire 11 and the copper wires 12 such that the relation between the cross-sectional area percentages correspond to those calculated in the previous steps ± 1%, more preferably ± 0.5 %, even more preferably 0.1 %.

[0043] The individual wires which are arranged to be assembled into the electrical conductor 1 can be any number and have any cross-sectional area. The appearance of the individual wires depends on what is suitable to arrive at a conductor having both the desired dimension and the corresponding relation between the area percentages. For example: The aluminum wire 11 and the individual copper wires 12 can have different or the same cross-sectional area, the cross-sectional area of the aluminum wire can be larger or smaller than that of the individual copper wires 12, the individual copper wires 12 can each have the same or different cross-sectional areas, the copper wires 12 can be any amount of wires, the copper wires 12 can be arranged around the aluminum wire 11 in one or a plurality of layers.

[0044] The invention also relates to a method for manufacturing a cable 6 comprising one or more of the electrical conductor 1. An exemplary embodiment of the cable 6 can be seen in Fig 2. The method of manufacturing the cable 6 comprises providing at least one electrical conductor 1 and providing each of the at least one electrical conductor 1 with a jacket 2 of insulation wherein the jacket 2 can be of any type used for cables and of any suitable material such as a polymer-based material, for example TPS 130. Furthermore, the method comprises providing a filling material

3. The filling material 3 can be of any type used in cables and of any suitable material such as a polymer-based material. Surrounding the at least one insulated electrical conductor 1 and the filling material 3, a binder 4 is provided. Surrounding the binder

4, an outer coating 5 is provided.

[0045] A possible version of the cable 6, namely the cable 6’, can be seen in Fig 3. The cable 6’ comprises only one of the electrical conductor 1. The method of manufacturing the cable 6’ comprises providing one electrical conductor 1 and providing it with a jacket 2. Surrounding the insulated electrical conductor 1 , an outer coating 5 is provided.

[0046] A method of manufacturing an electrical conductor and a method for manufacturing a cable have been shown and described. It will be realized that the inventive idea is not limited to the embodiments disclosed herein but can be varied within the scope of the appended claims without departing from the inventive idea.