Power cable, conductor, cable connection structure, and cable termination connection structure

Abstract

The power cable includes a conductor including copper strands containing copper or a copper alloy and aluminum strands containing aluminum or an aluminum alloy, and at least a portion of the copper strands and at least a portion of the aluminum strands are in contact with each other.

Description

[Technical field]

[0001] The present disclosure relates to power cables, conductors, cable connection structures, and cable termination connection structures. [Background technology]

[0002] In recent years, conductors in which copper wires are replaced with aluminum wires have been adopted in some cases (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-128135 A Summary of the Invention

[0004] According to one aspect of the present disclosure, there is provided a power cable comprising a conductor including copper wires containing copper or a copper alloy and aluminum wires containing aluminum or an aluminum alloy, wherein at least a portion of the copper wires and at least a portion of the aluminum wires are in contact with each other. [Brief description of the drawings]

[0005] [Figure 1A] FIG. 1A is a schematic cross-sectional view perpendicular to the axial direction of a first example of a power cable according to a first embodiment of the present disclosure. [Figure 1B] FIG. 1B is a schematic cross-sectional view perpendicular to the axial direction of a second example of the power cable according to the first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along the axial direction of a conductor, showing a cable connection structure according to the first embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic cross-sectional view taken along the axial direction of a conductor, showing a cable connection structure according to a first modified example of the first embodiment of the present disclosure. [Figure 4]FIG. 4 is a schematic cross-sectional view taken along the axial direction of a conductor, illustrating a cable termination structure according to a second modification of the first embodiment of the present disclosure. [Figure 5A] FIG. 5A is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a second embodiment of the present disclosure. [Figure 5B] FIG. 5B is a schematic cross-sectional view showing the state before the segment of FIG. 5A is compression molded. [Figure 6A] FIG. 6A is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a third embodiment of the present disclosure. [Figure 6B] FIG. 6B is a schematic cross-sectional view showing the state before the segment of FIG. 6A is compression molded. [Figure 7] FIG. 7 is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a fourth embodiment of the present disclosure. [Figure 8] FIG. 8 is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a fifth embodiment of the present disclosure. [Figure 9] FIG. 9 is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a sixth embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic cross-sectional view perpendicular to the axial direction of a conductor of a power cable according to a seventh embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] [Problem that this disclosure aims to solve] An object of the present disclosure is to improve various properties of power cables containing aluminum wires.

[0007] [Effects of this disclosure] According to the present disclosure, it is possible to improve various characteristics of a power cable including an aluminum wire.

[0008] [Description of the embodiments of the present disclosure] <Knowledge gained by the inventors> First, the findings of the inventors will be described.

[0009] In power cables, the conductors may include conventional copper strands, but also, as mentioned above, may include aluminum strands.

[0010] However, when the conductor contains only copper wires, and when the conductor contains only aluminum wires, the following problems arise.

[0011] (Conductor containing only copper wires) In a conductor containing only copper wires, an insulating oxide film does not form around the outer circumference of the copper wires, so the power cable can be easily and stably connected by compressing the tips of a pair of conductors at a specified pressure using a sleeve.

[0012] However, in a conductor that includes only bare copper wires without an insulating coating, as the cross-sectional area increases, a skin effect occurs in AC, increasing AC resistance, and thus reducing power transmission efficiency.

[0013] For this reason, in conductors that only contain copper wires, the skin effect has been suppressed by using segmented conductors that are divided into multiple segments with insulating paper between them, or by using insulated wire conductors in which the outer circumference of each copper wire is covered with an insulating coating. However, these methods tend to increase costs such as processing costs and connection construction costs.

[0014] (Conductor containing only aluminum wires) The resistivity of aluminum wire is higher than that of copper wire, so to make the resistance of a conductor containing only aluminum wires equivalent to that of a conductor containing only copper wires, it was necessary to increase the size (cross-sectional area) of the conductor.

[0015] The tensile properties (tensile strength) of aluminum wires are inferior to those of copper wires, so the mechanical strength of conductors containing only aluminum wires tends to be lower than that of conductors containing only copper wires.

[0016] On the other hand, in a conductor containing only aluminum wires, an insulating oxide film (natural oxide film) forms around each aluminum wire, which has the same effect as the above-mentioned wire-insulated conductor, thereby suppressing the skin effect.

[0017] However, with a conductor containing only aluminum wires, it has been difficult to connect a power cable due to the presence of an oxide film on the outer periphery of the aluminum wires.

[0018] For example, if a conductor containing only aluminum wires is not strongly compressed by the sleeve, the oxide film cannot be broken and the connection resistance cannot be reduced. When the sleeve is strongly compressed in this way, the aluminum wires in the sleeve are easily broken.

[0019] In order to obtain the desired connection resistance without excessively compressing the sleeve, it is necessary to increase the compression length of the sleeve. For example, in the case of an overhead transmission line containing only aluminum wires (cross-sectional area 20 to 20 mm 2 ) required a sleeve compression length of 300 to 400 mm. This sleeve compression length was too long for a connection structure for a power cable laid underground. Therefore, it was difficult to adopt a normal sleeve compression method for the cable connection structure.

[0020] For this reason, a method of welding individual aluminum wires between a pair of conductors has been adopted up until now, but the welding work requires special skills, which results in long working hours and high costs.

[0021] Other methods of connecting aluminum wires that have been considered include removing the oxide film from each aluminum wire when connecting the cable by explosive welding or the like, but these methods have the potential to make the process of connecting conductors that contain aluminum wires complicated or difficult, and to result in unstable connection resistance.

[0022] (Review by the inventors) Therefore, after extensive research, the inventors discovered a configuration that solves the above-mentioned problems and improves various characteristics of the power cable by configuring the conductor to include both copper wires and aluminum wires and optimizing the arrangement of the copper wires and aluminum wires.

[0023] The present disclosure is based on the above findings made by the present inventors.

[0024] <Embodiments of the present disclosure> Next, embodiments of the present disclosure will be listed and described.

[0025] [1] A power cable according to one embodiment of the present disclosure comprises: A conductor including a copper wire including copper or a copper alloy and an aluminum wire including aluminum or an aluminum alloy, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. This configuration can improve various characteristics of the power cable including the aluminum wires.

[0026] [2] In the power cable according to the above [1], The copper strands and the aluminum strands are arranged alternately in at least a portion of the conductor. According to this configuration, even if the conductor includes copper wires as bare wires, the skin effect can be suppressed.

[0027] [3] The power cable according to the above [1] or [2], the conductor has a plurality of wire layers including at least one of the copper wires and the aluminum wires, The copper wires and the aluminum wires are each provided in at least two of the plurality of wire layers. According to this configuration, the conductor can have the resistance and mechanical strength required, and the weight of the power cable can be reduced, thereby reducing the manufacturing cost of the power cable.

[0028] [4] In the power cable according to any one of [1] to [3] above, The ratio of the number of the copper wires in the outermost periphery of the conductor to the total number of the copper wires and the aluminum wires in the outermost periphery of the conductor is 20% or more. According to this configuration, the aluminum oxide film on the inner aluminum wires can be broken by the copper wires at the outermost periphery of the conductor.

[0029] [5] The power cable according to [4] above, The outermost circumference of the conductor has at least one aluminum wire. According to this configuration, at least one aluminum wire can prevent direct contact between the copper wires at the outermost periphery of the conductor.

[0030] [6] The power cable according to any one of [1] to [3] above, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; each of the plurality of segments has an arc region that constitutes an outermost periphery of the conductor; The ratio of the number of the copper wires in the arc region to the total number of the copper wires and the aluminum wires in the arc region of each of the plurality of segments is 20% or more. According to this configuration, the aluminum oxide film on the inner aluminum wires can be broken by the copper wires on the outermost periphery of the segment.

[0031] [7] The power cable according to [6] above, The arc region of each of the plurality of segments includes at least one aluminum wire. According to this configuration, at least one aluminum wire can prevent direct contact between the copper wires at the outermost periphery of the segment.

[0032] [8] The power cable according to any one of [1] to [4] above, The conductor is A copper wire layer including only the copper wire; an aluminum wire layer including only the aluminum wire; having The copper wire layers and the aluminum wire layers are alternately arranged in the radial direction of the conductor. This configuration can reduce eddy currents that cross between the wire layers in AC, but is also suitable for DC.

[0033] [9] The power cable according to any one of [1] to [3] and [6] above, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; Each of the plurality of segments comprises: A copper wire layer including only the copper wire; an aluminum wire layer including only the aluminum wire; having The copper wire layers and the aluminum wire layers are alternately arranged in the radial direction of each of the plurality of segments. This configuration can reduce eddy currents that cross between the wire layers in AC, but is also suitable for DC.

[0034]

[10] The power cable according to any one of [1] to [7] above, The copper wire is provided in plurality, The aluminum wire is provided in plurality, The copper wires and the aluminum wires are arranged in a mottled pattern. According to this configuration, the skin effect can be suppressed stably.

[0035]

[11] The power cable according to any one of [1] to [3], [6], and [7] above, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; Each of the plurality of segments comprises: an aluminum wire layer including only the aluminum wires and not including the copper wires; a composite wire layer including the copper wire and the aluminum wire; having The aluminum wire layers and the composite wire layers are alternately arranged in the radial direction of each of the plurality of segments. According to this configuration, the skin effect can be suppressed stably.

[0036]

[12] The power cable according to any one of [1] to [3], [6], and [7] above, The conductor has a plurality of composite strand layers including the copper strands and the aluminum strands, In each of the plurality of composite wire layers, one copper wire and two or more consecutive aluminum wires are alternately arranged in the circumferential direction of each of the plurality of composite wire layers. According to this configuration, the skin effect can be stably suppressed, and the number of aluminum wires can be increased.

[0037]

[13] The power cable according to

[11] or

[12] above, The copper wire is provided in plurality, The aluminum wire is provided in plurality, The copper wires are arranged in a mottled pattern so as not to be in contact with one another. According to this configuration, the skin effect can be suppressed stably.

[0038]

[14] The power cable according to any one of [1] to [3], [6], [7], and

[11] to

[13] above, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; At positions where each of the plurality of segments contacts the other segments, only the aluminum wire is disposed. According to this configuration, the multiple segments can be insulated from each other without providing insulating paper between the multiple segments.

[0039]

[15] The power cable according to any one of [1] to

[14] above, The aluminum wire has a natural aluminum oxide film on its outer periphery. According to this configuration, no special processing is required to form an oxide film on the aluminum wire.

[0040]

[16] The power cable according to

[15] above, At the connection between the conductor and another conductor, the native oxide film of the aluminum wire is broken by the copper wire, In the non-connected portion between the conductor and another conductor, the native oxide film of the aluminum wire is not broken. According to this configuration, it is possible to achieve both a stable connection of the power cable and suppression of the skin effect in AC.

[0041]

[17] A conductor according to another aspect of the present disclosure includes: It is used in the power cable according to any one of the above [1] to

[16] . This configuration can improve various characteristics of the power cable including the aluminum wires.

[0042]

[18] A cable connection structure according to another aspect of the present disclosure includes: a first power cable having a first conductor; a second power cable having a second conductor; a cylindrical sleeve connecting the first conductor and the second conductor; Equipped with At least the first conductor includes a copper wire including copper or a copper alloy, and an aluminum wire including aluminum or an aluminum alloy, Within the first conductor, at least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. This configuration can improve various characteristics of the power cable including the aluminum wires.

[0043]

[19] A cable termination structure according to yet another aspect of the present disclosure includes: a power cable having a conductor; a sleeve surrounding a tip of the conductor of the power cable; a porcelain tube into which the power cable with the sleeve attached is inserted; having The conductor includes a copper wire including copper or a copper alloy, and an aluminum wire including aluminum or an aluminum alloy, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. This configuration can improve various characteristics of the power cable including the aluminum wires.

[0044] [Details of the embodiment of the present disclosure] Next, an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0045] First Embodiment of the Present Disclosure (1) Power cables and conductors A power cable 100 and a conductor 110 according to a first embodiment of the present disclosure will be described with reference to FIG. 1A or FIG. 1B.

[0046] In each cross-sectional view perpendicular to the axial direction of the conductor 110 of the present disclosure, copper wires 112a described below are hatched with oblique lines, and aluminum wires 112b are not hatched.

[0047] In the following, the "axial direction" of the power cable 100 refers to the direction along the central axis of the power cable 100. The "radial direction" of the power cable 100 refers to the direction from the central axis of the power cable 100 toward the outer periphery. The "circumferential direction" of the power cable 100 refers to the direction along the outer periphery of the power cable 100. The same terms as those for the power cable 100 may be used for the conductor 110, the segment 111, the conductor wires 112, and the sleeve 200.

[0048] As shown in FIG. 1A or FIG. 1B, power cable 100 is configured as a solid insulated cable that is a high-voltage power transmission cable.

[0049] The power cable 100 may be for AC or DC. In the second to seventh embodiments described below, similarly to the first embodiment, the power cable 100 may be for AC or DC.

[0050] 1A as a first example, a power cable 100 has, for example, a conductor 110, an inner semiconductive layer 120, an insulating layer 130, an outer semiconductive layer 140, a water absorbing layer (not shown), a metallic shielding layer 150, and a sheath 160, in this order from the central axis of the conductor 110 toward the outer periphery of the power cable 100. The metallic shielding layer 150 is, for example, a metal coating or a wound layer of copper wire or copper tape.

[0051] 1B is configured as an underwater cable (submarine cable, undersea cable, etc.), and includes a conductor 110, an inner semiconductive layer 120, an insulating layer 130, an outer semiconductive layer 140, a water absorbing layer (not shown), a metal shielding layer 150, and an outer peripheral structure 170, in this order from the central axis of the conductor 110 toward the outer periphery of the power cable 100. The outer peripheral structure 170 in the underwater cable includes, for example, a corrosion protection layer, a seat yarn layer, an iron wire exterior (armoring), and a yarn layer, from a region close to the conductor 110 toward the outer periphery. The metal shielding layer 150 in the underwater cable is, for example, a metal sheath.

[0052] In the following description, for the sake of simplicity, the outside of the metal shielding layer 150 may be described as a sheath 160 .

[0053] (conductor) The conductor 110 includes, for example, a plurality of conductor wires 112. Each of the plurality of conductor wires 112 has a circular cross section, which makes it possible to easily manufacture the conductor wires 112.

[0054] The conductor 110 has, for example, a plurality of strand layers 114. The plurality of strand layers 114 are, for example, stacked in the radial direction of the conductor 110. The plurality of strand layers 114 are, for example, arranged concentrically around the central axis of the conductor 110. In each strand layer 114 except for the center of the conductor 110, the plurality of conductor strands 112 are, for example, arranged so as to cover the outer periphery of the inner strand layer 114 and are twisted in a spiral shape along the outer periphery of the inner strand layer 114.

[0055] Here, the conductor 110 has, for example, five concentric wire layers 114. Hereinafter, the five wire layers 114 are named, from the central axis of the conductor 110 toward the outer periphery, as a first wire layer 114a, a second wire layer 114b, a third wire layer 114c, a fourth wire layer 114d, and a fifth wire layer 114e. The first wire layer 114a, the second wire layer 114b, the third wire layer 114c, the fourth wire layer 114d, and the fifth wire layer 114e include 1, 6, 12, 18, and 24 conductor wires 112, respectively.

[0056] In this embodiment, the conductor 110 includes, for example, both the copper wires 112a and the aluminum wires 112b. By including the aluminum wires 112b in the conductor 110 in this manner, the weight of the power cable 100 can be reduced, and the manufacturing cost of the power cable 100 can be reduced.

[0057] The copper wire 112a includes, for example, copper or a copper alloy. The copper wire 112a is, for example, a soft copper wire. The copper wire 112a is a so-called bare wire, and does not have an insulating coating on its outer periphery.

[0058] The aluminum wire 112b includes, for example, aluminum or an aluminum alloy. The aluminum wire 112b has, for example, a natural aluminum oxide film on its outer periphery. In other words, the aluminum wire 112b is not anodized. This makes it possible to eliminate the need for special processing to form an oxide film on the aluminum wire 112b.

[0059] The thickness of the aluminum natural oxide film on the aluminum wire 112b is thinner than the thickness of the oxide film formed by anodizing. Specifically, the thickness of the aluminum natural oxide film on the aluminum wire 112b is, for example, 0.1 nm or more and 100 nm or less. In the following disclosure, unless otherwise specified, the term "oxide film" of the aluminum wire 112b simply means the natural oxide film.

[0060] In this embodiment, for example, at least a part of the copper wire 112a and at least a part of the aluminum wire 112b are in contact with each other. As a result, in a cable connection structure 20 (a connection portion between a conductor 110 and another conductor 110) described below, when the sleeve 200 is compressed, the copper wire 112a, which is harder than the aluminum wire 112b, can break at least a part of the oxide film of the aluminum wire 112b. As a result, even with simple compression, conduction between the pair of conductors 110 can be ensured.

[0061] On the other hand, in portions other than the cable connection structure 20 (non-connected portions between the conductor 110 and other conductors 110), the aluminum wires 112b are not compressed by the copper wires 112a. Therefore, the oxide film of the aluminum wires 112b is not broken, and the insulating properties of the oxide film are maintained.

[0062] In this embodiment, the copper wires 112a and the aluminum wires 112b are, for example, arranged alternately in at least a portion of the conductor 110. This makes it possible to suppress the skin effect in at least a portion of the conductor 110 by utilizing the oxide film of the aluminum wires 112b.

[0063] In this embodiment, the copper wires 112a and the aluminum wires 112b are each provided in at least two of the multiple wire layers 114. Providing the copper wires 112a in at least two wire layers 114 makes it possible to obtain the resistance and mechanical strength required for the conductor 110. Providing the aluminum wires 112b in at least two wire layers 114 makes it possible to reduce the weight of the power cable 100 and the manufacturing cost of the power cable 100.

[0064] In this embodiment, the ratio of the number of copper wires 112a at the outermost periphery of the conductor 110 to the total number of copper wires 112a and aluminum wires 112b at the outermost periphery of the conductor 110 is, for example, 20% or more. This makes it possible to easily ensure electrical continuity between the sleeve 200 described below and the copper wires 112a at the outermost periphery of the conductor 110. Furthermore, the copper wires 112a at the outermost periphery of the conductor 110 can break the aluminum oxide film on the inner aluminum wires 112b.

[0065] In this embodiment, the conductor 110 has, for example, a copper strand layer including only the copper strands 112a and an aluminum strand layer including only the aluminum strands 112b as the strand layers 114. The copper strand layers and the aluminum strand layers are alternately arranged in the radial direction of the conductor 110.

[0066] Specifically, the first strand layer 114a, the second strand layer 114b, the third strand layer 114c, the fourth strand layer 114d, and the fifth strand layer 114e are a copper strand layer, an aluminum strand layer, a copper strand layer, an aluminum strand layer, and a copper strand layer, respectively.

[0067] The above-mentioned arrangement can reduce eddy currents that cross between the wire layers 114. As a result, the skin effect can be suppressed.

[0068] In this embodiment, the outermost wire layer 114 is, for example, a copper wire layer as described above. That is, the ratio of the number of copper wires 112a in the outermost fifth wire layer 114e is 100%. By using a copper wire layer that does not produce an oxide film as the outermost wire layer 114, it is possible to stably ensure electrical continuity between the sleeve 200 and the outermost copper wire layer, which will be described later, and electrical continuity between the outermost copper wire layer and the inner aluminum wire layer.

[0069] However, the outermost periphery of the conductor 110 may have at least one aluminum wire 112b. This makes it possible to prevent direct contact between the copper wires 112a at the outermost periphery of the conductor 110 by the at least one aluminum wire 112b. As a result, it is possible to stably suppress the skin effect in AC.

[0070] In this embodiment, a so-called water-propagation suppression layer that suppresses water propagation may be provided between adjacent wire layers 114. The water-propagation suppression layer is formed of, for example, a water-running prevention tape. This makes it possible to suppress the propagation of water along the axial direction of the conductor 110.

[0071] However, since the water-propagation prevention tape serving as the water-propagation suppression layer is insulating, adjacent wire layers sandwiching the water-propagation prevention tape are insulated from each other.

[0072] In contrast, in this embodiment, the water propagation suppression layer between adjacent wire layers 114 is removed at the connection between the conductor 110 and another conductor 110. By not providing a water propagation suppression layer at the connection between the conductor 110 and another conductor 110 in this way, in the cable connection structure 20, the copper wire layer can be pressed against the adjacent aluminum wire layer, and the oxide film of the aluminum wire 112b in the aluminum wire layer can be broken. This ensures electrical continuity between adjacent wire layers 114.

[0073] (Coefficient ks specified in IEC60287 1-1) In this embodiment, as described above, the insulating properties of the oxide film of the aluminum wire 112b are maintained in parts other than the cable connection structure 20, thereby making it possible to suppress the skin effect compared to a conductor that includes only copper wires as bare wires.

[0074] Here, the International Electrotechnical Commission IEC60287 1-1 (Edition 2.0) specifies a coefficient ks as an index showing the tendency of the skin effect. The coefficient ks corresponds to the split conductor coefficient KS1 specified in the Japanese Electric Wire & Cable Standards JCS0501.

[0075] The coefficient ks is calculated as follows in accordance with IEC 60287 1-1 (Edition 2.0 2014-11).

[0076] The AC resistance per unit length of a conductor at its maximum operating temperature, except for pipe-type cables, is given by the following equation (1): R = R' (1 + ys + yp) (1)

[0077] where R is the AC resistance of the conductor at the maximum operating temperature in Ω / m. R' is the DC resistance of the conductor at the maximum operating temperature in Ω / m. ys is the skin effect factor. yp is the proximity effect factor.

[0078] The DC resistance per unit length of a conductor at its maximum operating temperature is given by equation (2) below. R'=R0{1+α20(θ-20)} ···(2)

[0079] where R0 is the DC resistance of the conductor at 20°C in Ω / m. α20 is the constant mass temperature at 20°C. θ is the maximum operating temperature in°C.

[0080] The skin effect factor ys is given by the following equation (3).

[0081]

number

[0082] Here, xs is given by the following equation (4) using the coefficient ks.

[0083]

number

[0084] f is the frequency (Hz). Although formula (3) is an approximation, it is accurate as long as xs does not exceed 2.8, so it is applicable in many practical cases.

[0085] The proximity effect coefficient yp is given by the following equation (5).

[0086]

number

[0087] Here, xp is given by the following equation (6) using a coefficient kp.

[0088]

number

[0089] dc is the diameter of the conductor (mm). S is the distance between the central axes of the conductors (mm). Although formula (5) is an approximation, it is accurate as long as xp does not exceed 2.8, so it is applicable in many practical cases.

[0090] The coefficient ks is calculated based on the above equations (1) to (6).

[0091] Here, Table 2 of the International Electrotechnical Commission IEC 60287 1-1 (Edition 2.0 2014-11 revised version) states that the coefficient ks for a conductor in which all strands are bare copper strands (hereinafter also referred to as an "all-bare copper strand conductor") is 0.62. Table 2 also states that the coefficient ks for a conductor in which all strands are bare aluminum strands with an oxide film (hereinafter also referred to as an "all-aluminum strand conductor") is 0.25.

[0092] In contrast, in this embodiment, the conductor 110 includes copper wires 112a and aluminum wires 112b as bare wires, and the copper wires 112a and aluminum wires 112b are arranged as described above, thereby suppressing the skin effect.

[0093] As a result, in this embodiment, the coefficient ks of the conductor 110 determined in accordance with the above IEC 60287 1-1 (Edition 2.0 2014-11) is smaller than the coefficient ks of an all-bare copper strand conductor, for example. Note that the coefficient ks of the conductor 110 of this embodiment is larger than the coefficient ks of an all-aluminum strand conductor or is as close as possible to the coefficient ks of an all-aluminum strand conductor.

[0094] That is, the coefficient ks of the conductor 110 of this embodiment is, for example, equal to or greater than 0.25 and less than 0.62. As a result, even if the conductor 110 includes copper strands 112a, it is possible to achieve a low AC resistance close to the AC resistance of an all-strand insulated conductor (all-aluminum strand conductor).

[0095] (2) Connecting power cables and cable connection structures A schematic configuration of a linked power cable 10 and a cable connection structure (cable connection portion) 20 according to an embodiment of the present disclosure will be described with reference to FIG.

[0096] 2 and later-described Fig. 3 show the stepped stripped side of the power cable 100 except for the conductor 110. Also, the lower side of each of Fig. 2 and later-described Fig. 3 is omitted.

[0097] As shown in FIG. 2, the linked power cable 10 of this embodiment includes, for example, a plurality of power cables 100 and at least one cable connection structure 20.

[0098] (Cable connection structure) 2, the cable connection structure 20 is configured to connect, for example, a pair of power cables 100, and is configured as a so-called factory joint. Specifically, the cable connection structure 20 has, for example, a first power cable 100a, a second power cable 100b, a sleeve 200, an inner semiconductive layer 220, an insulating layer 230, an outer semiconductive layer 240, a water-absorbent tape layer 242, a metal tube (protective tube) 250, and an anticorrosive layer (connection portion sheath) 260.

[0099] (Power Cable) The first power cable 100a and the second power cable 100b each have a first conductor 110a and a second conductor 110b. Each of the first conductor 110a and the second conductor 110b includes both copper strands 112a and aluminum strands 112b, as described above.

[0100] (Sleeve (conductor connection tube)) The sleeve 200 is provided, for example, so as to surround a connection point (connection portion, connection location) at which the conductors 110 of a pair of power cables 100 are connected to each other. Note that the cylindrical sleeve 200 may have a partition wall (not shown) between the pair of conductors 110 in the hollow portion.

[0101] The sleeve 200 is configured, for example, as a cylindrical metal tube having a hollow portion (reference numeral not shown). In the hollow portion of the sleeve 200, exposed portions of the pair of conductors 110 including the connection points are inserted.

[0102] Examples of metals that form the sleeve 200 include copper (pure copper), copper alloys, aluminum, and aluminum alloys. When the sleeve 200 is made of aluminum or an aluminum alloy, it is preferable to increase the thickness of the sleeve 200 so that the electrical resistance per cross-sectional area is equivalent to that of pure copper.

[0103] The sleeve 200 is compressed, for example, in the radial direction of the conductor 110. The sleeve 200 is compressed, for example, to have a cross-sectional shape that is symmetrical with respect to the central axis of the sleeve 200. The cross-sectional shape of the sleeve 200 perpendicular to the axial direction after compression is, for example, a polygon (hexagon) or a circle. Note that the sleeve 200 does not have an indent that is locally recessed in the radial direction of the sleeve 200. By compressing the sleeve 200 in this manner, the pair of conductors 110 are connected.

[0104] In this embodiment, the sleeve 200 is compressed, for example, so that the copper wires 112a break at least a part of the oxide film on the aluminum wires 112b. This makes it possible to ensure a required electrical conductivity in the cable connection structure 20.

[0105] In an all-aluminum wire conductor, in which all wires have an oxide film, the sleeve needs to be compressed with a pressure (stress) of about 100 MPa to break the oxide film of the aluminum. In this case, when the sleeve is compressed, the aluminum wires are significantly deformed, and there is a risk that the aluminum wires may break.

[0106] In contrast, in this embodiment, as described above, the copper wire 112a is disposed around the aluminum wire 112b. The Young's modulus of copper is 130 GPa, and the Young's modulus of aluminum is 70 GPa. Therefore, copper is less likely to deform than aluminum. As a result, even if the sleeve 200 is compressed with a pressure of less than 100 MPa, the copper wire 112a can break at least a part of the oxide film of the aluminum wire 112b. In addition, a pressure of 80 MPa or more is desirable to obtain good contact. Furthermore, the deformation of the aluminum wire 112b can be suppressed, and the breakage of the aluminum wire 112b can be prevented. As a result, the conduction between the pair of conductors 110 can be stably ensured.

[0107] In this embodiment, the axial length of the sleeve 200 (compressed length of the sleeve 200) in each of the first conductor 110a and the second conductor 110b (i.e., on one side) is not particularly limited, and may be, for example, 50 mm or more and 200 mm or less.

[0108] (Outer structure of the sleeve) An inner semiconductive layer 220, an insulating layer 230, an outer semiconductive layer 240, an outer semiconductive layer 240, a water absorbing tape layer 242, a metal tube 250, and a corrosion protection layer 260 are provided in this order from the area close to the sleeve 200 toward the outside so as to cover the outer periphery of the sleeve 200. These can be configured as described in, for example, JP 2023-065809 A as a general configuration of a factory joint.

[0109] (3) Summary of this embodiment According to this embodiment, one or more of the following advantages are achieved.

[0110] (a) In this embodiment, the conductor 110 includes both copper wires 112a and aluminum wires 112b. This allows the resistance of the conductor 110 to be equivalent to the resistance of a conductor including only copper wires, without excessively increasing the size of the conductor 110. Furthermore, it is possible to suppress a decrease in the mechanical strength of the conductor 110, which is caused by the conductor 110 including the aluminum wires 112b.

[0111] (b) In this embodiment, at least a part of the copper wire 112a and at least a part of the aluminum wire 112b are in contact with each other. As a result, in the cable connection structure 20, when the sleeve 200 is compressed, the copper wire 112a, which is harder than the aluminum wire 112b, can break at least a part of the oxide film of the aluminum wire 112b. As a result, even if the sleeve 200 is simply compressed, conduction between the pair of conductors 110 can be ensured. In this way, according to this embodiment, the conductor 110 can easily and stably connect the power cable 100 including the aluminum wire 112b.

[0112] (c) In this embodiment, even if the sleeve 200 is compressed with low pressure, electrical continuity between the pair of conductors 110 can be easily ensured. This makes it possible to prevent breakage of the aluminum wires 112b inside the sleeve 200 caused by strong compression of the sleeve 200. As a result, the mechanical strength of the cable connection structure 20 can be ensured, and it becomes possible to prevent a decrease in the tensile tension of the conductors 110. For example, this embodiment can be applied to cases where a large tension is applied to the connection portion of the conductors 110, such as in deep-sea installation.

[0113] (d) In the present embodiment, conduction between a pair of conductors 110 including the aluminum wires 112b can be stably ensured without excessively increasing the axial length of the sleeve 200. This makes it possible to prevent the overall length of the cable connection structure 20 from increasing. As a result, it is possible to reduce the connection resistance of the cable connection structure 20 while suppressing a decrease in the tensile tension of the conductors 110 described above, without excessively increasing the axial length of the sleeve 200.

[0114] (e) In the present embodiment, it is possible to eliminate the need to weld each of the aluminum wires 112b between the pair of conductors 110. This eliminates the need for special skills required for welding. In addition, compared to the welding method, it is possible to shorten the work time and reduce the cost of the work.

[0115] (f) In this embodiment, the copper wires 112a and the aluminum wires 112b are alternately arranged in at least a portion of the conductor 110. This allows the copper wires 112a as bare wires to be enclosed in a portion where the copper wires 112a as bare wires are sandwiched between a plurality of aluminum wires 112b by utilizing the oxide film of the aluminum wires 112b. As a result, even if the conductor 110 includes the copper wires 112a as bare wires, the skin effect can be suppressed in at least a portion of the conductor 110.

[0116] (g) In this embodiment, the copper wires 112a and the aluminum wires 112b are alternately arranged in at least a portion of the conductor 110, which increases the number of conductive points where the copper wires 112a break at least a portion of the oxide film of the aluminum wires 112b inside the compressed sleeve 200. This reduces the electrical resistance at the connection portion of the pair of conductors 110. As a result, it becomes possible to suppress abnormal heat generation at the connection portion of the pair of conductors 110.

[0117] (h) In this embodiment, at the connection portion between the conductor 110 and another conductor 110, the natural oxide film of the aluminum wire 112b is broken by the copper wire 112a. On the other hand, at the non-connection portion between the conductor 110 and another conductor 110, the natural oxide film of the aluminum wire 112b is not broken. That is, at the non-connection portion between the conductor 110 and another conductor 110, the natural oxide film of the aluminum wire 112b is selectively maintained and used to suppress the skin effect. With this configuration, it is possible to achieve both stable connection of the power cable 100 and suppression of the skin effect in AC.

[0118] (i) In this embodiment, the conductor 110 has, as the wire layer 114, a copper wire layer including only the copper wires 112a and an aluminum wire layer including only the aluminum wires 112b. The copper wire layers and the aluminum wire layers are alternately arranged in the radial direction of the conductor 110.

[0119] With the above-mentioned arrangement, the copper wire layer can be confined by utilizing the oxide film of the aluminum wire 112b in the portion where the copper wire layer is sandwiched between the pair of aluminum wire layers. This makes it possible to reduce eddy currents crossing between the wire layers 114. As a result, even if the conductor 110 includes the copper wire 112a as a bare wire, it is possible to suppress the skin effect.

[0120] With the above-described arrangement, in the cable connection structure 20, the sleeve 200 is compressed in the radial direction, so that the copper wire layer can be reliably pressed against the aluminum wire layer. This allows the copper wires 112a in the copper wire layer to break at least a part of the oxide film of the aluminum wires 112b in the aluminum wire layer. As a result, it is possible to stably ensure conduction in the radial direction (i.e., the compression direction) of the sleeve 200.

[0121] With the above-described arrangement, conductor wires 112 having the same composition are continuously arranged in the same wire layer 114. This makes it possible to easily manufacture the conductor 110.

[0122] (j) In this embodiment, the copper wires 112a having no oxide film are arranged continuously in the circumferential direction of the copper wire layer. That is, in the same copper wire layer, the copper wires 112a are electrically connected to each other. From this point of view, the power cable 100 of this embodiment is more suitable for DC than the other embodiments described later.

[0123] (4) Modification of the First Embodiment The above-described embodiment can be modified as necessary as in the following modified examples. Hereinafter, only elements different from the above-described embodiment will be described, and elements substantially the same as those described in the above-described embodiment will be given the same reference numerals and their description will be omitted. In the second to seventh embodiments described later, the description will be omitted as in the modified examples of the first embodiment.

[0124] In the following modified examples 1 and 2, the cable connection structure is different from that of the above-described embodiment.

[0125] <Variation 1> As shown in FIG. 3, the cable connection structure 20 of the first modified example has, for example, a first power cable 100a, a second power cable 100b, a sleeve 200, a sleeve cover 290, an insulating unit (rubber connection tube, rubber unit, insulating tube) 300, a protective tube (metal tube) 400, and a filler 480.

[0126] The first power cable 100a and the second power cable 100b of the first modification are configured similarly to those of the above-described first embodiment.

[0127] As in the first embodiment, the sleeve 200 is compressed such that the copper wires 112a break at least a part of the oxide film of the aluminum wires 112b. A cylindrical sleeve cover 290 may be provided to surround the outer periphery of the sleeve 200.

[0128] The insulating unit 300 is configured, for example, as an insulating tubular member, and is provided so as to cover the outer periphery of the sleeve 200 (the outer periphery of the sleeve cover 290) and a portion of the outer periphery of each of the pair of power cables 100.

[0129] The insulating unit 300 is configured as, for example, a so-called cold shrink type. That is, the insulating unit 300 has an elastic material (rubber) molded as an integral unit, and is configured to elastically shrink at room temperature to come into close contact with the connection portion of the power cable 100.

[0130] The insulating unit 300 includes, for example, an inner semiconductive layer 320 , an insulating layer 340 , a stress cone portion 360 , and an outer semiconductive layer 380 .

[0131] The metallic protective tube 400 is provided so as to cover the outer periphery of the insulating unit 300 and part of the outer periphery of each of the pair of power cables 100, and is configured to protect them.

[0132] The filler 480 is filled between the insulating unit 300 and the protective tube 400 within the protective tube 400. As the filler 480, for example, a so-called waterproof compound can be used.

[0133] (Summary of Variation 1) According to the first modification, even with the cable connection structure 20 using the insulating unit 300, it is possible to obtain the same effects as those of the first embodiment described above.

[0134] <Variation 2> 4, the cable termination structure 22 of the second modification is configured to terminate, for example, a power cable 100. Specifically, the cable termination structure 22 has, for example, the power cable 100, a sleeve 200, a metal strip 214, an insulating unit 300, and a porcelain tube 500.

[0135] The power cable 100 of the second modification is configured similarly to the power cable 100 of the above-described first embodiment.

[0136] The sleeve 200 has, for example, a cylindrical portion 216 and a rod-shaped portion 218. The exposed portion of the conductor 110 of the power cable 100 is inserted into the cylindrical portion 216, and the copper wires 112a are compressed so as to break at least a part of the oxide film of the aluminum wires 112b. The rod-shaped portion 218 is provided on the opposite side of the cylindrical portion 216.

[0137] The insulating unit 300 includes, for example, an insulating layer 340 and a semiconductive layer 350. The semiconductive layer 350 forms a so-called stress cone.

[0138] The porcelain pipe 500 is configured in a cylindrical shape so that the power cable 100 to which the sleeve 200 and the insulating unit 300 are attached can be inserted. The porcelain pipe 500 is erected in the vertical direction. The rod-shaped portion 218 of the sleeve 200 attached to the tip of the power cable 100 is fixed to the vertical upper end of the porcelain pipe 500. On the other hand, the opening at the vertical lower end of the porcelain pipe 500 is sealed. In this state, the porcelain pipe 500 is filled with an insulating medium 520 such as insulating oil.

[0139] (Summary of Variation 2) According to the second modification, even with the cable termination structure 22, it is possible to obtain the same effects as those of the first embodiment described above.

[0140] <Second embodiment of the present disclosure> Next, a second embodiment of the present disclosure will be described with reference to FIGS. 5A and 5B.

[0141] 5A, and Fig. 6A and Fig. 7 to Fig. 10, which will be described later, some of the conductor wires 112 are omitted. In each figure, the segments 111 that are not shown have the same configuration as the segments 111 that have been shown.

[0142] 5A, the conductor 110 of this embodiment is configured as a so-called divided conductor. The conductor 110 has, for example, a plurality of segments 111 and insulating paper .

[0143] The multiple segments 111 are provided around the central axis of the conductor 110. The multiple segments 111 are arranged, for example, rotationally symmetrically around the central axis of the conductor 110. In this embodiment, the number of segments 111 is, for example, four. The four segments 111 are arranged with four-fold rotational symmetry around the central axis of the conductor 110.

[0144] The segment 111 includes, for example, a plurality of twisted conductor wires 112. The segment 111 is compression molded from the state shown in Fig. 5B into a sector-shaped cross section as shown in Fig. 5A. The pressure applied when compressing the segment 111 is lower than the pressure applied to compress the sleeve 200 in the cable connection structure 20 described above. For this reason, in the non-connected portion between the conductor 110 and another conductor 110, the natural oxide film of the aluminum wires 112b in the segment 111 is not broken.

[0145] The segment 111 has, for example, a plurality of strand layers 114. The plurality of strand layers 114 are, for example, stacked in the radial direction of the segment 111. In each strand layer 114 except for the center of the segment 111, the plurality of conductor strands 112 are, for example, arranged so as to cover the outer periphery of the inner strand layer 114 and are twisted in a spiral shape along the outer periphery of the inner strand layer 114.

[0146] Each of the multiple segments 111 has an arc region (reference number not shown) that forms the outermost periphery of the conductor 110. In other words, the arc region corresponds to a region of the outermost strand layer 114 that is not in contact with other segments 111.

[0147] In this embodiment, the segment 111 includes both the copper wires 112a and the aluminum wires 112b. At least a portion of the copper wires 112a and at least a portion of the aluminum wires 112b are in contact with each other in the segment 111. The copper wires 112a and the aluminum wires 112b are alternately arranged in at least a portion of the segment 111.

[0148] In this embodiment, in each segment 111, the copper wires 112a and the aluminum wires 112b are provided in at least two of the plurality of wire layers 114.

[0149] In this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, 20% or more. This makes it possible to easily ensure electrical continuity between the sleeve 200 and the outermost copper wires 112a of the segment 111. Furthermore, the outermost copper wires 112a of the segment 111 can break the aluminum oxide film of the inner aluminum wires 112b.

[0150] In this embodiment, the segment 111 has, for example, a copper wire layer including only the copper wires 112a and an aluminum wire layer including only the aluminum wires 112b as the wire layer 114. The copper wire layers and the aluminum wire layers are alternately arranged in the radial direction of the segment 111.

[0151] Specifically, in the segment 111, for example, the first wire layer 114a, the second wire layer 114b, the third wire layer 114c, the fourth wire layer 114d, and the fifth wire layer 114e are a copper wire layer, an aluminum wire layer, a copper wire layer, an aluminum wire layer, and a copper wire layer, respectively. That is, the proportion of the copper wires 112a in the outermost fifth wire layer 114e is 100%.

[0152] However, each of the arc regions of the multiple segments 111 may have at least one aluminum wire 112b. This makes it possible to prevent direct contact between the copper wires 112a at the outermost periphery of the segments 111 by the at least one aluminum wire 112b.

[0153] For example, the insulating paper 116 is sandwiched between adjacent segments 111. Thus, the adjacent segments 111 are insulated from each other by the insulating paper 116. As a result, the effective surface area of ​​the conductor 110 is increased, and the skin effect can be suppressed.

[0154] The cross-sectional area of ​​the conductor 110 is not particularly limited, but is, for example, 1000 mm 2 or more, or 2500 mm 2 That's all.

[0155] (Summary of the second embodiment) According to this embodiment, by alternately arranging the copper wires 112a and the aluminum wires 112b in at least a part of the segments 111 of the conductor 110 as a divided conductor, it is possible to suppress the skin effect even if the cross-sectional area of ​​the conductor 110 as a divided conductor is increased in a state where the conductor 110 as a divided conductor includes the copper wires 112a as bare wires. As a result, it is possible to reduce the AC resistance of the power cable 100 while increasing the capacity of the power cable 100.

[0156] <Third embodiment of the present disclosure> 6A, the conductor 110 of this embodiment is configured as a divided conductor, similar to the second embodiment, and has a plurality of segments 111 and insulating paper 116. However, the arrangement inside the conductor 110 of this embodiment is different from the arrangement in the second embodiment.

[0157] The segments 111 are compression molded from the state shown in Fig. 6B into a sector-shaped cross section as shown in Fig. 6A. The number of segments 111 is, for example, five.

[0158] In this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, 20% or more.

[0159] On the other hand, in this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 may be, for example, 98% or less, 80% or less, or 70% or less. This makes it possible to reduce the number of continuous copper wires 112a due to the aluminum wires 112b at the outermost circumference of the conductor 110, and to suppress direct contact between the copper wires 112a. As a result, it is possible to suppress an increase in AC resistance caused by direct contact between the copper wires 112a at the outermost circumference of the conductor 110.

[0160] In this embodiment, the multiple copper wires 112a are arranged in a mottled pattern so as not to be in contact with one another within the segment 111. Each copper wire 112a is surrounded by multiple aluminum wires 112b.

[0161] In this embodiment, the wire layers 114 constituting the segment 111 are classified into at least two types, for example. Specifically, the segment 111 has, for example, an aluminum wire layer and a composite wire layer. The aluminum wire layer does not include, for example, the copper wires 112a, and is composed only of the aluminum wires 112b. On the other hand, the composite wire layer includes the copper wires 112a and the aluminum wires 112b. In the composite wire layer, for example, at least one copper wire 112a is interposed between the aluminum wires 112b adjacent to each other in the circumferential direction of the wire layer 114. In the composite wire layer of this embodiment, for example, the aluminum wires 112b and the copper wires 112a are alternately arranged in the circumferential direction of the wire layer 114. The aluminum wire layers and the composite wire layers are alternately arranged in the radial direction of the segment 111. When the second wire layer 114b is an aluminum wire layer, the first wire layer 114a may be a copper wire layer made of one copper wire 112a.

[0162] Specifically, within the segment 111, for example, the first wire layer 114a, the second wire layer 114b, the third wire layer 114c, the fourth wire layer 114d, and the fifth wire layer 114e are a copper wire layer, an aluminum wire layer, a composite wire layer, an aluminum wire layer, and a composite wire layer, respectively.

[0163] In this embodiment, due to the above-mentioned arrangement, the multiple copper wires 112a are arranged in a mottled manner so as not to be in contact with one another.

[0164] (Summary of the third embodiment) (a) According to this embodiment, in the segment 111 of the conductor 110 as a divided conductor, the copper wires 112a are arranged in a mottled manner so as not to contact each other, and in each copper wire 112a surrounded by the aluminum wires 112b, the copper wires 112a as bare wires can be confined by utilizing the oxide film of the aluminum wires 112b. This makes it possible to stably suppress the skin effect even if the cross-sectional area of ​​the conductor 110 is increased in a state in which the conductor 110 as a divided conductor includes the copper wires 112a as bare wires. As a result, it is possible to stably reduce the AC resistance of the power cable 100 while increasing the capacity of the power cable 100.

[0165] (b) In this embodiment, in the segment 111 of the conductor 110 as a divided conductor, each copper wire 112a is surrounded by a plurality of aluminum wires 112b, so that the entire outer periphery of the copper wire 112a can break at least a part of the oxide film of the plurality of aluminum wires 112b in the compressed sleeve 200. This makes it possible to reduce the electrical resistance at the connection part of the pair of conductors 110 while increasing the number of aluminum wires 112b.

[0166] <Fourth embodiment of the present disclosure> 7, the conductor 110 of this embodiment is configured as a divided conductor, similar to the third embodiment, and has a plurality of segments 111 and insulating paper 116. However, the arrangement inside the conductor 110 of this embodiment is different from the arrangement in the third embodiment.

[0167] In this embodiment, the copper wires 112a and the aluminum wires 112b are arranged in a mottled pattern.

[0168] Specifically, the segment 111 has a plurality of composite wire layers including, for example, copper wires 112a and aluminum wires 112b. The plurality of composite wire layers are stacked in the radial direction of the segment 111. In each of the plurality of composite wire layers, one copper wire 112a and one aluminum wire 112b are alternately arranged in the circumferential direction of the respective composite wire layers.

[0169] In this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, not less than 40% and not more than 60%.

[0170] (Summary of the fourth embodiment) (a) According to this embodiment, a plurality of copper wires 112a and a plurality of aluminum wires 112b are arranged in a mottled pattern. Aluminum wires 112b having an oxide film are interposed between the plurality of copper wires 112a. The plurality of copper wires 112a are not in direct contact with each other. This makes it possible to stably suppress the skin effect in AC.

[0171] (b) According to this embodiment, the copper wires 112a and the aluminum wires 112b are evenly distributed within the conductor 110. In other words, the conductor wires 112 having the same composition are not locally concentrated. This allows the mechanical strength of the conductor 110 to be evenly distributed. As a result, the stress applied to the conductor 110 can be prevented from being locally concentrated.

[0172] <Fifth embodiment of the present disclosure> 8, the conductor 110 of this embodiment is configured as a divided conductor, similar to the fourth embodiment, and has a plurality of segments 111 and insulating paper 116. However, the arrangement inside the conductor 110 of this embodiment is different from the arrangement in the fourth embodiment.

[0173] In this embodiment, the segment 111 has a plurality of composite wire layers including, for example, copper wires 112a and aluminum wires 112b. The plurality of composite wire layers are stacked in the radial direction of the segment 111. In each of the plurality of composite wire layers, one copper wire 112a and two or more consecutive aluminum wires 112b are alternately arranged in the circumferential direction of the plurality of composite wire layers. In this embodiment, two consecutive aluminum wires 112b are arranged in each of the plurality of composite wire layers. Note that the first wire layer 114a located at the center of the segment 111 is either the copper wire 112a or the aluminum wire 112b.

[0174] In this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, not less than 30% and not more than 40%.

[0175] (Summary of the fifth embodiment) (a) According to this embodiment, in each of the multiple composite wire layers, two or more aluminum wires 112b having an oxide film are interposed between the multiple copper wires 112a. This makes it possible to stably suppress the skin effect in AC.

[0176] (b) According to the present embodiment, it is possible to increase the number of aluminum wires 112b in the conductor 110. This allows the weight of the power cable 100 to be reduced, and the manufacturing cost of the power cable 100 to be reduced.

[0177] Sixth embodiment of the present disclosure 9, the conductor 110 of this embodiment is configured as a divided conductor, similar to the fourth and fifth embodiments, and has a plurality of segments 111 and insulating paper 116. However, the arrangement inside the conductor 110 of this embodiment is different from the arrangement in the fourth and fifth embodiments.

[0178] In this embodiment, one copper wire 112a and three or more consecutive aluminum wires 112b are alternately arranged in the circumferential direction of each of the multiple composite wire layers. In this embodiment, four consecutive aluminum wires 112b are arranged in each of the multiple composite wire layers.

[0179] The number of aluminum wires interposed between a pair of copper wires 112a in a portion of each wire layer 114 may be less than that in the outermost fifth wire layer 114e.

[0180] In this embodiment, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, not less than 20% and not more than 30%.

[0181] In this embodiment, the copper wires 112a may be arranged in a mottled manner so as not to be in contact with one another due to the above-mentioned arrangement.

[0182] (Summary of the sixth embodiment) (a) According to this embodiment, it is possible to obtain the same effects as those of the fifth embodiment.

[0183] (b) According to the present embodiment, the number of aluminum wires 112b in the conductor 110 can be increased compared to that in the fifth embodiment. This allows the weight of the power cable 100 to be further reduced, and the manufacturing cost of the power cable 100 can be further reduced.

[0184] Seventh embodiment of the present disclosure 10, the conductor 110 of this embodiment is configured as a divided conductor, similar to the third to sixth embodiments, and has a plurality of segments 111. However, the arrangement inside the conductor 110 of this embodiment is different from the arrangements in the third to sixth embodiments. Furthermore, the conductor 110 of this embodiment does not have insulating paper 116.

[0185] In this embodiment, only aluminum wires 112b are arranged at positions where each of the multiple segments 111 contacts the other segments 111. As a result, no insulating paper 116 is provided between the multiple segments 111.

[0186] Specifically, the segment 111 has, for example, a composite wire layer including copper wires 112a and aluminum wires 112b as the outermost fifth wire layer 114e. At the position where the outermost fifth wire layer 114e contacts other segments 111, only the aluminum wires 112b are continuously arranged.

[0187] On the other hand, there is no particular limitation on the arrangement of the copper wires 112a and the aluminum wires 112b at a position where the outermost fifth wire layer 114e does not contact other segments 111. In this embodiment, at a position where the outermost fifth wire layer 114e does not contact other segments 111, for example, the aluminum wires 112b and the copper wires 112a are alternately arranged in the circumferential direction of the fifth wire layer 114e.

[0188] In the present embodiment as well, the ratio of the number of copper wires 112a in the arc region to the total number of copper wires 112a and aluminum wires 112b in the arc region of each of the multiple segments 111 is, for example, 20% or more. In the example of the fifth wire layer 114e of the present embodiment, the ratio of the number of copper wires 112a in the arc region may be, for example, 40% or more and 60% or less.

[0189] The wire layers 114 inside the outermost fifth wire layer 114e are not particularly limited. In this embodiment, for example, the first wire layer 114a, the second wire layer 114b, the third wire layer 114c, and the fourth wire layer 114d are an aluminum wire layer, a copper wire layer, an aluminum wire layer, and a copper wire layer, respectively.

[0190] (Summary of the Seventh Embodiment) According to this embodiment, only aluminum wires 112b are arranged at positions where each of the multiple segments 111 contacts the other segments 111, so that the multiple segments 111 can be insulated from each other without providing insulating paper 116 between the multiple segments 111. As a result, the configuration of the conductor 110 can be simplified.

[0191] (Summary of all embodiments) As described above, depending on the various characteristics required for the power cable 100, it is possible to select any one of the first to seventh embodiments described above, or to combine at least two of the first to seventh embodiments.

[0192] <Other embodiments of the present disclosure> Although the embodiments of the present disclosure have been specifically described above, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0193] In the above-mentioned first embodiment and modified example 1, the first conductor 110a and the second conductor 110b in the cable connection structure 20 each include both the copper wire 112a and the aluminum wire 112b, but the present disclosure is not limited to this case. It is sufficient that at least the first conductor 110a includes both the copper wire 112a and the aluminum wire 112b. In this case, the second conductor 110b may include only the copper wire 112a.

[0194] In the above-mentioned first embodiment and modified example 1, the linking power cable 10 has one cable connection structure 20, but the linking power cable 10 may have a plurality of cable connection structures 20.

[0195] In the above embodiment, the application of the compound is not mentioned, but the application of the compound in the present disclosure is not limited. For example, a compound containing metal particles may be provided between the inner peripheral surface of the sleeve 200 and the outer peripheral surface of the conductor 110. This allows the electrical resistance to be stably reduced. On the other hand, there may be no compound between the inner peripheral surface of the sleeve 200 and the outer peripheral surface of the conductor 110. This prevents the resin component or oil component in the compound from evaporating even if the connected power cable 10 becomes hot.

[0196] In the above-mentioned second to seventh embodiments, the cable connection structure was not described, but the power cable 100 of the second to seventh embodiments can be applied to a cable connection structure 20 similar to that of the first embodiment, a cable connection structure 20 similar to that of the first modified example, or a cable termination connection structure 22 similar to that of the second modified example.

[0197] In the above-mentioned second to seventh embodiments, a case has been described in which the conductor 110 is a divided conductor having a plurality of segments 111. However, the above-mentioned second to seventh embodiments may also be applied to a conductor 110 configured as a circular conductor having a circular cross section.

[0198] In all of the above-described embodiments, the total number of conductor wires 112, the number of segments 111, the number of conductor wires 112 in each wire layer 114, and the number of wire layers 114 may be changed as appropriate. [Explanation of symbols]

[0199] 10 Connecting power cable 20 Cable connection structure 22 Cable termination structure 100 Power Cable 100a First power cable 100b Second power cable 110 Conductor 110a First conductor 110b Second conductor 111 Segments 112 Conductor wire 112a copper wire 112b Aluminum wire 114 Strand layer 114a 1st strand layer 114b 2nd wire layer 114c 3rd strand layer 114d 4th strand layer 114e 5th strand layer 116 Insulating Paper 120 Inner semiconducting layer 130 Insulating layer 140 Outer semiconducting layer 150 Metal shielding layer 160 Sheath 170 Peripheral structure 200 sleeve 214 Metal strip 216 Cylindrical part 218 Rod-shaped part 220 Inner semiconducting layer 230 Insulating layer 240 Outer semiconducting layer 242 Water-absorbing tape layer 250 metal tube 260 Anticorrosive Layer 290 Sleeve Cover 300 Isolation Unit 320 Inner semiconducting layer 340 Insulating layer 350 Semiconductive layer 360 Stress Cone Section 380 Outer semiconducting layer 400 Protection tube 480 Filling material 500 Pipe 520 Insulating Media

Claims

1. A conductor including a copper wire including copper or a copper alloy and an aluminum wire including aluminum or an aluminum alloy, a ratio of the number of the copper wires in the outermost circumference of the conductor to the total number of the copper wires and the aluminum wires in the outermost circumference of the conductor is 20% or more; The outermost circumference of the conductor has at least one aluminum wire, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

2. The copper wires and the aluminum wires are arranged alternately in at least a portion of the conductor.

2. The power cable according to claim 1.

3. the conductor has a plurality of wire layers including at least one of the copper wires and the aluminum wires, The copper wires and the aluminum wires are each provided in at least two wire layers among the plurality of wire layers.

3. The power cable according to claim 1 or 2.

4. A conductor including a copper wire containing copper or a copper alloy and an aluminum wire containing aluminum or an aluminum alloy, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; each of the plurality of segments has an arc region that constitutes an outermost periphery of the conductor; a ratio of the number of the copper wires in the arc region to the total number of the copper wires and the aluminum wires in the arc region of each of the plurality of segments is 20% or more; the arc region of each of the plurality of segments includes at least one aluminum wire; At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

5. A conductor including a copper wire containing copper or a copper alloy and an aluminum wire containing aluminum or an aluminum alloy, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; Each of the plurality of segments comprises: A copper wire layer including only the copper wire; an aluminum wire layer including only the aluminum wire; having the copper wire layers and the aluminum wire layers are alternately arranged in a radial direction of each of the plurality of segments; At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

6. A conductor including a copper wire containing copper or a copper alloy and an aluminum wire containing aluminum or an aluminum alloy, The copper wire is provided in plurality, The aluminum wire is provided in plurality, the plurality of copper wires and the plurality of aluminum wires are arranged in a mottled pattern, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

7. A conductor including a copper wire containing copper or a copper alloy and an aluminum wire containing aluminum or an aluminum alloy, the conductor comprises a plurality of segments including the copper strands and the aluminum strands; Each of the plurality of segments comprises: an aluminum wire layer including only the aluminum wires and not including the copper wires; a composite wire layer including the copper wire and the aluminum wire; having the aluminum wire layers and the composite wire layers are alternately arranged in a radial direction of each of the plurality of segments, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

8. A conductor including a copper wire containing copper or a copper alloy and an aluminum wire containing aluminum or an aluminum alloy, The conductor has a plurality of composite strand layers including the copper strands and the aluminum strands, In each of the plurality of composite wire layers, one copper wire and two or more consecutive aluminum wires are alternately arranged in a circumferential direction of each of the plurality of composite wire layers, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

9. The copper wire is provided in plurality, The aluminum wire is provided in plurality, The copper wires are arranged in a mottled pattern so as not to be in contact with each other.

9. The power cable according to claim 7 or 8.

10. A conductor comprising: a copper wire containing copper or a copper alloy; and an aluminum wire containing aluminum or an aluminum alloy; the conductor comprises a plurality of segments including the copper strands and the aluminum strands; Only the aluminum wire is disposed at a position where each of the plurality of segments contacts the other segments, At least a portion of the copper wire and at least a portion of the aluminum wire are in contact with each other. Power cable.

11. The aluminum wire has a natural oxide film of aluminum on its outer periphery. The power cable according to any one of claims 1, 2, 4 to 8 and 10.

12. At the connection between the conductor and another conductor, the native oxide film of the aluminum wire is broken by the copper wire, The native oxide film of the aluminum wire is not broken in the non-connected portion between the conductor and another conductor.

12. The power cable of claim 11.

13. The power cable according to any one of claims 1, 2, 4 to 8, and 10 is used. conductor.

14. A first power cable having the conductor according to claim 13 as a first conductor; a second power cable having a second conductor; a cylindrical sleeve connecting the first conductor and the second conductor; Equipped Cable connection structure.

15. A power cable having the conductor according to claim 13; a sleeve surrounding a tip of the conductor of the power cable; a porcelain tube into which the power cable with the sleeve attached is inserted; have Cable termination structure.

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