Aluminium conductors

Abstract

A conductor is suitable for use in a high-voltage cable, and includes an aluminium alloy, in which the aluminium alloy comprises one or more of a group 3, 4 or 5 element and/or a lanthanide, each with a concentration in the range of 0.006 to 0.03% (m/m). The conductor has undergone a thermal treatment at a temperature from the range of 185° C. to 315° C. during a period from the range of 12 hours to 24 hours, so that the conductor has a conductivity of 61% IACS or more.

Claims

1. An overhead high-voltage line comprising a conductor, the conductor being formed as a wire or a plurality of wires drawn from wire rod, wherein the conductor includes an aluminium alloy, wherein the aluminium alloy includes one or several of a group 3, 4 or 5 element and optionally a lanthanide, each with a concentration in the range 0.006 to 0.030%(m/m), wherein the conductor has undergone a thermal treatment in the form of the drawn wire or wires at a temperature from within the range 185° C. to 315° C. for a period from within the range 12 hours to 24 hours, wherein the conductor has undergone the thermal treatment before any cabling or stranding of the wire or wires to form the overhead high-voltage line, and wherein the conductor has a conductivity of 61% IACS or more.

2. The overhead high-voltage line according to claim 1, in which the aluminium alloy comprises 99.5%(m/m) or more aluminium.

3. The overhead high-voltage line according to claim 1, in which the aluminium alloy comprises 0.00 to 0.02%(m/m) yttrium and/or erbium.

4. The overhead high-voltage line according to claim 1, in which the aluminium alloy furthermore also comprises 0.1 to 0.3%(m/m) iron.

5. The overhead high-voltage line according to claim 1 in which: the group 3 element is scandium or yttrium or a combination thereof, the group 4 element is titanium, zirconium or hafnium or a combination thereof, the group 5 element is niobium or tantalum or a combination thereof, and the lanthanide is lanthanum, cerium, praseodymium or erbium or a combination thereof.

6. The overhead high-voltage line according to claim 1, in which the aluminium alloy comprises 0.008 to 0.010%(m/m) zirconium, and in which the thermal treatment comprises a treatment at a temperature of 270 to 290° C. for 12 to 24 hours.

7. The overhead high-voltage line according to claim 1, in which the aluminium alloy comprises 0.013 to 0.020%(m/m) zirconium, and in which the thermal treatment comprises a treatment at a temperature of 185 to 225° C. for 12 to 24 hours.

8. The overhead high-voltage line according to claim 1, in which the aluminium alloy comprises 0.020 to 0.025%(m/m) zirconium, and in which the thermal treatment comprises a treatment at a temperature of 200 to 240° C. for 12 to 24 hours.

9. The overhead high-voltage according to claim 1, further comprising a core and one or several conductors.

10. The overhead high-voltage line according to claim 9, in which the core comprises composite or steel or invar.

11. A method for the production of the high-voltage line according to claim 1, the method including the production of a conductor by melting of technically pure aluminium in a melting furnace, alloying of the alloy elements, continuously casting of a profile and in-line rolling of the profile within a temperature range of 380° C. to 540° C., drawing of the conductor from the wire rod to the end diameter, and performing the thermal treatment of the wires with the end diameter.

12. An overhead high-voltage line comprising a conductor, the conductor being formed as a wire or a plurality of wires drawn from wire rod, wherein the conductor includes an aluminium alloy, wherein the aluminium alloy includes one or several of a group 3, 4 or 5 element, each with a concentration in the range 0.006 to 0.030%(m/m), wherein the conductor has undergone a thermal treatment in the form of the drawn wire or wires at a temperature from within the range 185° C. to 315° C. for a period from within the range 12 hours to 24 hours, wherein the conductor has undergone the thermal treatment before any cabling or stranding of the wire or wires to form the overhead high-voltage line, and wherein the conductor has a conductivity of 61% IACS or more.

13. The overhead high-voltage line according to claim 12, in which the aluminium alloy comprises a lanthanide with a concentration in the range 0.006 to 0.030%(m/m).

14. An overhead high-voltage line comprising a conductor, the conductor being formed as a wire or a plurality of wires drawn from wire rod, wherein the conductor includes an aluminium alloy, wherein the aluminium alloy comprises one or several of a group 3, 4 or 5 element with a concentration in the range 0.006 to 0.030%(m/m), wherein the aluminium alloy optionally comprises a lanthanide with a concentration in the range 0.006 to 0.030%(m/m), and wherein, before any cabling or stranding of the wire or wires to form the overhead high-voltage line, the conductor has a conductivity of 61% IACS or more.

Description

SHORT DESCRIPTION OF THE FIGURES

(1) FIGS. 1(a) to 1(c) illustrate a side view of a cable according to an embodiment of the present invention, as well as a cross section of a cable according to various embodiments of the present compound.

(2) The figures are only schematic and not restrictive. It is possible that the dimensions of some components have been exaggerated and have not been represented to scale in the figures for illustrative purposes.

(3) Reference numbers used in the claims cannot be interpreted to restrict the scope of protection. In the various figures, the same reference numbers refer to the same or similar elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(4) The present invention will be described in respect of special embodiments and with reference to certain drawings, however the invention will not be restricted to this but will only be restricted by the claims. The drawings described are only schematic and not restrictive. In the drawings, the dimensions of some elements may have been enlarged and not have been drawn to scale for illustrative purposes. The dimensions and the relative dimensions sometimes do not correspond with the up-to-date practical embodiment of the invention.

(5) Furthermore, the terms first, second, third and the like in the description and in the claims are used to distinguish similar elements and are not necessarily used for describing an order, nor in time, nor in space, nor in ranking nor in any other manner. It should be understood that the terms used in this way are interchangeable in appropriate circumstances and that the embodiments of the invention described herein are suitable to work in a different order than described or indicated here.

(6) Furthermore, the terms top, bottom, above, in front of and the like used in the description and the claims are used for description purposes and not necessarily to describe relative positions. It should be understood that the terms used as such are interchangeable in given circumstances and that the embodiments of the invention described herein are also suitable for functioning according to different orientations than described or indicated here.

(7) It should be noted that the term “comprises”, as used in the claims, should not be interpreted as being restricted to the items described thereafter; this term does not exclude any other elements or steps. It may be interpreted as specifying the presence of the features, values, steps, or components indicated which are referred to but does not exclude the presence or addition of one or several other features, values, steps or components, or groups thereof. So, the extent of the expression “a device comprising items A and B” should not be restricted to devices consisting of components A and B only. It means that in respect of the present invention, A and B are the only relevant components of the device.

(8) Reference throughout this specification to “one embodiment” or “an embodiment” means that a specific feature, structure, or characteristic described in connection with the embodiment has been included in at least one embodiment of the present invention. So, the occurrence of the expressions “in one embodiment” or “in an embodiment” in various locations throughout this specification do not necessarily need to refer to the same embodiment all the time, but can do so. Furthermore, the specific features, structures or characteristics may be combined in any suitable manner as would be clear to a person skilled in the art on the basis of this publication, in one or several embodiments.

(9) Similarly, it should be appreciated that in the description of sample embodiments of the invention, various features of the invention are sometimes grouped together in one single embodiment, figure or description thereof intended to streamline the publication and to help the understanding of one or several of the various inventive aspects. This method of publication should therefore not be interpreted as a reflection of an intention that the invention requires more features than explicitly mentioned in each claim. Rather, as the following claims reflect, inventive aspects lie in fewer than all features of one single previously publicised embodiment. So, the claims following on from the detailed description have been explicitly included in this detailed description, with every independent claim being a separate embodiment of the invention.

(10) Furthermore, while some embodiments described herein comprise some, but not other, features included in other embodiments, combinations of features from various embodiments are intended to be within the scope of the invention, and form these various embodiments as would be understood by the person skilled in the art. For example, in the following claims, any of the embodiments described may be used in any combination.

(11) In the description provided here, a large number of specific details are raised. It may therefore be understood that embodiments of the invention may be embodied without these specific details. In other cases, well-known methods, structures, and techniques are not shown in detail in order to keep this description clear.

(12) Such as used herein, the international annealed copper standard (IACS) is a unit for electrical conductivity, relatively compared with an annealed copper conductor standard. A conductivity of 100% IACS thereby corresponds with 5.80×10.sup.7 siemens per metre at 20° C.

(13) Such as used herein, the thermal resistance, tensile strength and conductivity are characteristics of an aluminium conductor, which may be obtained as described in the IEC62004 standards.

(14) Such as used herein, a soft aluminium conductor is an aluminium conductor in an annealed state. This means that the thermal treatment has been executed such that the stretch in the conductor is high, such as more than 15%, for example more than 20% and even more than 40%. A soft aluminium conductor typically has a low tensile strength, for example 100 MPa or less, and a high conductivity, such as more than 61%, for example more than 61.5% or even up to 63%. Such as used herein, a hard aluminium conductor is an aluminium conductor which is not in an annealed state.

(15) Such as used herein, the ratios in composition for a conductor are always expressed in weight percentages % (m/m).

(16) Such as used herein, group 3, 4 or 5 elements mean those elements from group 3, group 4, or group 5 according to Mendeljev's table.

(17) Such as used herein, a conductor means a single wire. The stranding of conductors, around a core or not, results in a bare cable. Such cables may for example be used as high-voltage cables.

(18) In a first aspect, the present invention relates to a conductor suitable for use in a high-voltage cable. The conductor comprises an aluminium alloy, in which the aluminium alloy comprises one or more of a group 3, 4 or 5 element and/or a lanthanide, each with a concentration in the range of 0.006 to 0.03% (m/m), preferably in a range of 0.006 to 0.027% (m/m) such as for example in the range of 0.008 to 0.025% (m/m), and in which the conductor has undergone a thermal treatment, so that the conductor has a conductivity of 61% IACS or more. Within the present invention, it was found surprising that, after an appropriate thermal treatment, an aluminium conductor with a relatively high conductivity may be obtained based on these aluminium alloys. This relatively high conductivity may for example be equal or higher than that of hard pure aluminium (61% IACS), up to the conductivity of soft pure aluminium (63% IACS); depending on the specific composition of the alloy and the specific thermal treatment that were selected. When reference is made to pure aluminium, reference is made to technically pure aluminium with at least 99.7% aluminium. This may be advantageously used in the preparation of various soft or hard aluminium conductors with improved characteristics, i.e. with a higher conductivity, tensile strength and/or thermal resistance compared with known aluminium conductors. Furthermore, in certain embodiments, the improvement of one or several of these characteristics may be advantageously obtained without sacrificing the other characteristics, again compared with already known aluminium conductors.

(19) In embodiments, the aluminium alloy may comprise 99.5% (m/m) or more aluminium, preferably 99.65% (m/m) or more. A higher mass fraction of aluminium typically advantageously leads to a conductor with a higher conductivity.

(20) In embodiments, the aluminium alloy may furthermore also comprise 0.00 to 0.02% (m/m) yttrium and/or erbium, preferably 0.01% (m/m). A small mass fraction of yttrium and/or erbium typically advantageously leads to a conductor with a higher thermal resistance. In embodiments of the present invention, yttrium and/or erbium may both be used as single element, in combination with each other or in combination with one or several elements of groups III, IV and V from Mendeljev's table.

(21) In embodiments, the aluminium alloy may furthermore also comprise 0.1 to 0.3% (m/m) iron, preferably 0.12 to 0.18% (m/m). A small mass fraction of iron typically advantageously leads to a higher tensile strength and recrystallisation temperature, with only a minor influence on the conductivity.

(22) In embodiments, the thermal treatment may for example comprise a treatment at a temperature of 185 to 315° C. for 12 to 24 hours. Depending on the temperature chosen, a soft or a hard conductor may be advantageously obtained; a soft conductor typically has a higher conductivity but a lower tensile strength than a hard conductor. The duration of this thermal treatment, up to 24 hours, is advantageously considerably shorter than typically necessary for known hard aluminium conductors with a high thermal resistance, where the thermal treatment may for example reach up to 6 days.

(23) In embodiments, the group 3 elements may be scandium or yttrium or a combination thereof, the group 4 elements may be titanium, zirconium or hafnium or a combination thereof, the group 5 elements may be niobium or tantalum or a combination thereof, and the lanthanide may be lanthanum, cerium, praseodymium or erbium or a combination thereof.

(24) In embodiments, this conductor may have a cross section with a rather oval shape, such as circular (FIG. 1.a). In other embodiments, this conductor may have a cross section with a more angular shape, such as rather trapezoidal (FIG. 1.b). A more angular diameter may advantageously lead to a cable with a better space filling.

(25) In table 1 below, some preferable embodiments of the aluminium conductors according to the present invention are compared with known aluminium conductors.

(26) In a first preferable embodiment, the aluminium alloy may comprise 0.008 to 0.010% (m/m) zirconium, and the thermal treatment may comprise a treatment at a temperature of 270 to 290° C. for 12 to 24 hours. Furthermore, the aluminium alloy may also comprise 0.00 to 0.02% (m/m) yttrium and/or erbium, such as 0.01% (m/m) yttrium, and 0.1 to 0.3% (m/m) iron, such as 0.12 to 0.18% (m/m). In this manner, soft aluminium conductors may be advantageously obtained with a considerably higher tensile strength compared with pure soft aluminium conductors (+/−50% higher), with a same conductivity (63%) and a higher thermal resistance (180/220). These conductors may for example be advantageously used in high-voltage cables of the ‘aluminium conductors composite core (ACCC™)’ or ‘aluminium conductors steel supported (ACSS)’ type, where, in both cases, the tensile strength of the cable, and therefore the resistance versus deflection under load, is increased by the higher tensile strength of the soft aluminium conductor.

(27) In a second preferable embodiment, the aluminium alloy may comprise 0.013 to 0.020% (m/m) zirconium, and the thermal treatment may comprise a treatment at a temperature of 185 to 225° C. for 12 to 24 hours. Furthermore, the aluminium alloy may also comprise 0.00 to 0.02% (m/m) yttrium and/or erbium, such as 0.01% (m/m) yttrium, and 0.1 to 0.3% (m/m) iron, such as 0.12 to 0.18% (m/m). In this manner, hard aluminium conductors may be advantageously obtained with characteristics corresponding with AT1 AlZr conductors, however with a higher conductivity (61.5% vs 60%). These conductors may for example be advantageously used in high-voltage cables of the ACCC′ type, where the tensile strength of the cable is further increased, more so than is the case for the aluminium conductors mentioned earlier of the first preferable embodiment, at the expense of a reduction in the conductivity (61.5% vs 63%). On the other hand, these conductors may for example also be advantageously used in high-voltage cables of the ‘aluminium conductor steel reinforced (ACSR)’ type, where the thermal resistance and the conductivity of the cable are increased compared with pure hard aluminium.

(28) TABLE-US-00001 TABLE 1 Pure 1 2 3 The present invention Type of conductor Soft Hard Soft Hard Hard Chemical composition (in % (m/m)) Zr — — 0.008-0.010 0.013-0.020 0.020-0.025 Y — — 0.01 0.01 0.01 Fe — — 0.12-0.18 0.12-0.18 0.12-0.18 Mg — — — — — Si — — — — — Thermal treatment On Wire Wire Wire Wire Temp 1 420° C. NONE 280 +/− 10 205 +/− 20 220 +/− 20 Time 1 15  — 18 +/− 6 18 +/− 6 18 +/− 6 Temp 2 — — — — — Time 2 — — — — — Thermal resistance (in ° C.) 1 hour 150 255 230 255 400 hours 120 220 180 220 40 years  80 180 150 180 Tensile strength (in MPa) — to 2.6 mm 60- 170 90 169 169 2.6-2.9 mm 60- 170 90 166 166 2.9-3.5 mm 60- 165 90 162 162 3.5-3.8 mm 60- 160 90 162 162 3.8-4.0 mm 60-  160- 90 159 159 4.0-4.5 mm 60-  160- 90 159 159 Conductivity (in % IACS)  63.00   61.00 63.00 61.50 61.00 Extend (in % >15% >2.5% >2.5%

(29) In a third preferable embodiment, the aluminium alloy may comprise 0.020 to 0.025% (m/m) zirconium, and the thermal treatment may comprise a treatment at a temperature of 200 to 240° C. for 12 to 24 hours. Furthermore, the aluminium alloy may also comprise 0.00 to 0.02% (m/m) yttrium and/or erbium, such as 0.01% (m/m) yttrium, and 0.1 to 0.3% (m/m) iron, such as 0.12 to 0.18% (m/m). In this manner, hard aluminium conductors may be advantageously obtained with the same conductivity as pure hard aluminium (61%) but with a higher temperature resistance. Alternatively, these conductors may also be compared with the current aluminium alloys with high thermal resistance, where the conductors according to this third preferable embodiment have a thermal resistance between that of AT1 and AT3 AlZr conductors (180/220 vs 150/180 and 210/240) but with a higher conductivity (61% vs 60%). These conductors may for example again be advantageously used in high-voltage cables of the ACCC′ type, where the tensile strength of the cable is further increased, again more so than is the case for the aluminium conductors mentioned earlier of the first preferable embodiment, at the expense of a reduction in the conductivity (61% vs 63%). On the other hand, these conductors may for example also again be advantageously used in high-voltage cables of the ACSR type, where the thermal resistance is further increased, more so than is the case for the aluminium conductors mentioned earlier of the second preferable embodiment the conductivity, and the same conductivity as pure hard aluminium. The latter too may be an advantage in practice as it allows for exchanging existing pure hard aluminium conductors for aluminium conductors according to the present invention, without adjustments to the rest of the system.

(30) It should be noted that tolerances in temperatures may further depend on composition, trace elements and for example variations in the type of oven. The person skilled in the art may, where necessary, bring a more specific characterisation, depending on local variations such as the temperature process, the packaging, the diameters of the wire, the exact composition, etc. into account.

(31) In a second aspect, the present invention relates to a use of the conductor from the first aspect in a high-voltage cable. In embodiments, the conductor may correspond with embodiments of the first aspect.

(32) In a third aspect, the present invention relates to a high-voltage cable (1) comprising a core (2) and one or several conductors (3) according to the first aspect. A schematic representation of such a cable is shown in FIGS. 1(a) to 1(c). In embodiments, the conductor may correspond with embodiments of the first aspect.

(33) In embodiments, the core may comprise composite, steel, or invar.

(34) In embodiments, the core may comprise composite or steel, the aluminium alloy may comprise 0.008 to 0.010% (m/m) zirconium, and the thermal treatment may for example comprise a treatment at a temperature of 270 to 290° C. for 12 to 24 hours.

(35) In embodiments, the core may comprise composite or steel, the aluminium alloy may comprise 0.013 to 0.020% (m/m) zirconium, and the thermal treatment may comprise a treatment at a temperature of 185 to 225° C. for 12 to 24 hours.

(36) In embodiments, the core may comprise composite or steel, the aluminium alloy may comprise 0.020 to 0.025% (m/m) zirconium, and the thermal treatment may comprise a treatment at a temperature of 200 to 240° C. for 12 to 24 hours.

(37) In a fourth aspect, the present invention relates to an aluminium alloy suitable for use in the conductor according to the first aspect, which comprises one or several of a group 3, 4 or 5 element and/or a lanthanide, each with a concentration in the range of 0.006 to 0.03% (m/m), preferably in a range of 0.006 to 0.027% (m/m) such as for example in the range of 0.008 to 0.025% (m/m).

(38) In embodiments, the aluminium alloy may comprise 99.5% (m/m) or more aluminium, preferably 99.65% (m/m) or more.

(39) In embodiments, the aluminium alloy may furthermore also comprise 0.00 to 0.02% (m/m) yttrium or erbium, preferably 0.01% (m/m).

(40) In embodiments, the aluminium alloy may furthermore also comprise 0.1 to 0.3% (m/m) iron, preferably 0.12 to 0.18% (m/m).

(41) In embodiments, the aluminium alloy may be fully annealed.

(42) In embodiments, the group 3 elements may be scandium or yttrium or a combination thereof, the group 4 elements may be titanium, zirconium or hafnium or a combination thereof, the group 5 elements may be niobium or tantalum or a combination thereof, and the lanthanide may be lanthanum, cerium, praseodymium or erbium or a combination thereof.

(43) In a fifth aspect, the present invention relates to a use of the aluminium alloys according to the fourth aspect in the conductor according to the first aspect. In embodiments, the aluminium may correspond with embodiments of the fourth aspect.

(44) In a further aspect, the present invention relates to a method for the production of a conductor suitable for use in a high-voltage cable. The method includes melting of technically pure aluminium in a melting furnace, alloying of the alloy elements, continuously casting of a profile, rolling of the profile within a temperature range of 380° C. to 540° C., drawing of wires from a wire rod to the end diameter and thermal treating of the wires with end diameter. The method may furthermore yet also include a final deformation step, carried out on a drawing machine or in a cable machine. The method may furthermore also include stranding of the wires in a cabling machine for bare conductors.

(45) It is an advantage of embodiments of the present invention that the thermal treatment which determines the characteristics in respect of conductivity and tensile strength is carried out on the wires with the end diameter and not on the wire rod. This results in a conductor that combines the unique characteristics of a good conductivity, a good tensile strength, and a good thermal resistance.

(46) According to embodiments of the present invention, alloying of the alloy elements includes adding of alloy elements so that the composition corresponds with these as indicated for the conductors as described in the aspect mentioned above.

(47) In some embodiments, rolling of the profile may happen in a temperature range between 420° C. and 520° C., for example in a temperature range between 440° C. and 500° C.

(48) In some embodiments of the present invention, the method also includes cooling of the profile in the roller to a temperature in the range of 80° C. to 330° C., for example to a temperature in the range of 250° C. to 320° C. or to a temperature in the range of 80° C. to 160° C. or to a temperature in the range of 150° C. to 250° C. It is an advantage of some embodiments of the present invention that the tensile strength may be high, particularly when the temperature is lower when removing the profile from the roller.

(49) In some embodiments, the roller diameters are in a range of 8 mm to 25 mm, for example in a range of 9.5 mm to 18 mm, such as for example in a range of 9.5 mm to 12 mm.

(50) In some embodiments, the end diameters of the wires, or the equivalent end diameters—i.e. average diameter—if the wires are not round but of another shape in respect of their profile shape, are in the range of 1 mm to 7 mm, for example in the range of 2 mm to 5 mm.

(51) In some embodiments, the thermal treatment on the wires has been drawn on their end diameter, a thermal treatment in batch or in-line. It should be noted that the thermal treatment of the drawn conductor when it is on its end diameter allows for the specifically good characteristics of the conductor to be obtained, without any further thermal treatments being required, such as homogenisation of an ingot, annealing or ageing.

(52) Specific and preferable aspects of the invention have been included in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims and with features of other dependent claims such as indicated and not only as expressly brought forward in the claims.

(53) These and other aspects of the invention will be apparent from and be clarified by reference to the embodiment(s) described below.

(54) The various aspects can easily be combined, and the combinations will also correspond with embodiments according to the present invention.

(55) By way of illustration, embodiments not limited as a result, further examples of alloys according to examples of the present invention are given in tables 2 to 4 below.

(56) TABLE-US-00002 TABLE 2 Pure 1 2 3 4 The present invention Type of conductor Soft Hard Soft Soft Hard Hard Chemical composition (in %(m/m)) Sc — — 0.005-0.010 0.027 0.005- 0.027 Y and/or Er — — 0.01 0.01 0.01 0.01 Fe — — 0.12-0.18 0.12-0.18 0.12-0.18 0.12-0.18 Mg — — — — — — Si — — — — — — Thermal treatment On Wire Wire Wire Wire Wire Temp 1 420° C. NONE 280 +/− 10 280 +/− 10 220 +/− 20 220 +/− 20 (in ° C.) Time 1 15   — 18 +/− 6 18 +/− 6 18 +/− 6 18 +/− 6 (in hrs) Temp 2 — — — — — (in ° C.) Time 2 — — — — — (in hrs) Thermal resistance (in ° C.) 1 hour 150 255 255 230 280 400 hours 120 220 220 180 240 40 years  80 180 180 150 210 Tensile strength (in MPa) — to 2.6 mm 60- 170 90 125 169 169 2.6-2.9 mm 60- 170 90 125 166 166 2.9-3.5 mm 60- 165 90 125 162 162 3.5-3.8 mm 60- 160 90 125 162 162 3.8-4.0 mm 60-  160- 90 125 159 159 4.0-4.5 mm 60-  160- 90 125 159 159 Conductivity (in % IACS) 63.0    61.00 63.00 62.0 62.0 61.00 Extension >30   1-2% >50% >8% >2.5% >2.5%

(57) TABLE-US-00003 TABLE 3 Pure 1 2 3 4 The present invention Type of conductor Soft Hard Soft Soft Hard Hard Chemical composition (in %(m/m)) Er — — 0.025 0.01 0.025 0.01 Y — — 0.01 0.025 0.01 0.025 Fe — — 0.12-0.18 0.12-0.18 0.12-0.18 0.12-0.18 Mg — — — — — — Si — — — — — — Thermal treatment On Wire Wire Wire Wire Wire Temp 1 420° C. NONE 280 +/− 10 280 +/− 10 220 +/− 20 220 +/− 20 (in ° C.) Time 1 15   — 18 +/− 6 18 +/− 6 18 +/− 6 18 +/− 6 (in hrs) Temp 2 — — — — — (in ° C.) Time 2 — — — — — (in hrs) Thermal resistance (in ° C.) 1 hour 150 255 255 230 230 400 hours 120 220 220 180 180 40 years  80 180 180 150 150 Tensile strength (in MPa) — to 2.6 mm 60- 170 90 90 169 169 2.6-2.9 mm 60- 170 90 90 166 166 2.9-3.5 mm 60- 165 90 90 162 162 3.5-3.8 mm 60- 160 90 90 162 162 3.8-4.0 mm 60-  160- 90 90 159 159 4.0-4.5 mm 60-  160- 90 90 159 159 Conductivity (in % IACS)  63.00   61.00 63.00 63.0 61.50 61.50 Extension >30% 1-2% >15% >15% >2.5% >2.5%

(58) TABLE-US-00004 TABLE 4 Pure 1 2 3 The present invention Type of conductor Soft Hard Soft Hard Hard Chemical composition (in % (m/m)) Hf — — 0.008-0.010 0.013-0.020 0.020-0.025 Y or Er — — 0.01 0.01 0.01 Fe — — 0.12-0.18 0.12-0.18 0.12-0.18 Mg — — — — — Si — — — — — Thermal treatment On Wire Wire Wire Wire Temp 1 420° C. NONE 280 +/− 10 205 +/− 20 220 +/− 20 (in ° C.) Time 1 15 — 18 +/− 6 18 +/− 6 18 +/− 6 (in hrs) Temp 2 — — — — — (in ° C.) Time 2 — — — — — (in hrs) Thermal resistance (in ° C.) 1 hour 150 255 230 255 400 hours 120 220 180 220 40 years  80 180 150 180 Tensile strength (in MPa) — to 2.6 mm 60-65 170 90 169 169 2.6-2.9 mm 60-65 170 90 166 166 2.9-3.5 mm 60-65 165 90 162 162 3.5-3.8 mm 60-65 160 90 162 162 3.8-4.0 mm 60-65  160- 90 159 159 4.0-4.5 mm 60-65  160- 90 159 159 Conductivity (in % IACS) 63.00    61.00 63.00 62.00 61.50 Extension >30% 1-2% >15% >2.5% >2.5%