Compression stranded conductor and power cable

Abstract

To provide a compression stranded conductor and cable in which conductor resistance can be reduced without increasing a cable size.SOLUTION: A compression stranded conductor 10 comprises: a central stranded wire 11 which is formed by coaxially stranding a plurality of element wires 15 around a center line 14; and an outer layer stranded wire 12 which is formed by coaxially stranding a plurality of element wires 16 around the central stranded wire 11, where a composite stranded wire 13 which consists of the central stranded wire 11 and the outer layer stranded wire 12 is compressed, and a space factor R which is a ratio that the center line 14 and the plurality of element wires 15, 16 occupy for the cross section of the composite stranded wire 13 is 87.0% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a compressed stranded conductor and a power cable. [Background technology]

[0002] BACKGROUND ART Cables have been proposed that include compressed stranded conductors in which a plurality of wires are concentrically twisted around a center wire and compressed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-137850 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, greenhouse gas (GHG) emissions from electricity use, especially in factories, have become a concern. This is due to the conductor resistance of the wires, which causes losses. To compensate for these losses, power plants must generate electricity. The resulting GHG emissions (particularly carbon dioxide) are problematic. In other words, reducing losses can reduce GHG emissions. One method proposed to reduce losses is to increase the cable size, thereby reducing conductor resistance (raising the allowable current). However, this method significantly increases the cost of cable components such as terminals and the construction costs of laying the cables.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a compressed stranded conductor and a power cable that can reduce conductor resistance without increasing the cable size. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the compressed stranded conductor according to the present invention comprises: a central stranded wire in which a plurality of wires are concentrically stranded around a central wire; an outer layer stranded wire formed by twisting a plurality of wires concentrically around the central stranded wire; A compressed stranded conductor comprising: The concentric strand consisting of the central strand and the outer layer strand is compressed, and the space factor, which is the ratio of the central wire and the plurality of strands to the cross section of the concentric strand, is 87.0% or more.

[0007] In order to achieve the above-mentioned object, the power cable according to the present invention comprises: The compressed stranded conductor; and an insulating coating covering the compressed stranded conductor. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a compressed stranded conductor and a power cable that can reduce conductor resistance without increasing the cable size.

[0009] The present invention has been briefly described above. The details of the present invention will become clearer by reading the following detailed description of the invention (hereinafter referred to as "embodiments") with reference to the accompanying drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a power cable including a compressed stranded conductor according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram for explaining the manufacturing process of the power cable. [Figure 3] FIG. 3 is a schematic diagram for explaining the manufacturing process of the power cable. [Figure 4] FIG. 4 is a schematic diagram for explaining the manufacturing process of the power cable. [Figure 5] FIG. 5 is a schematic diagram for explaining the manufacturing process of the power cable. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a compressed stranded conductor 10 and a power cable 1 according to one embodiment of the present invention will be described with reference to the drawings. The power cable 1 can be adapted to, for example, a JISC3605:2002 600V polyethylene cable.

[0012] The present invention is not limited to the following embodiments, and can be modified, improved, etc. as appropriate. The material, shape, size, number, location, etc. of each component in the following embodiments are arbitrary and not limited as long as they can achieve the present invention.

[0013] [Outline of power cable configuration] The schematic configuration of the power cable 1 will be described below with reference to FIG. The power cable 1 is configured to include a compressed stranded conductor 10 and an insulating coating 20 that covers the compressed stranded conductor 10.

[0014] The compressed stranded conductor 10 includes a center strand 11 and outer layer strands 12. The compressed stranded conductor 10 is formed by twisting together a center wire 14 and multiple strands 15, 16 and compressing them. From the viewpoint of manufacturability, it is preferable that the center wire 14 and the multiple strands 15, 16 are all the same strand. The center wire 14 and the multiple strands 15, 16 are made of, for example, copper or a copper alloy. The center wire 14 and the multiple strands 15, 16 may also be made of, for example, an aluminum alloy, aluminum, copper, or a copper alloy.

[0015] The core strand 11 is formed by concentrically twisting a plurality of wires 15 (six in this example) around a core wire 14. The outer layer strand 12 is formed by twisting a plurality of wires 16 (twelve in this example) around the core strand 11 at the outer periphery of the core strand 11. In other words, the outer layer strand 12 is arranged in layers with respect to the core strand 11. In this example, the outer layer strand 12 is formed in one layer, but may be formed in two or more layers.

[0016] Here, the outer layer stranded wires 12 arranged around the central stranded wire 11 (after compression in this example) are referred to as a concentric stranded wire 13. The concentric stranded wire 13 is compressed using a compressor (e.g., a die). The compressed stranded wire conductor 10 is formed so that the space factor R is 87.0% or more and 95.0% or less. However, the compressed stranded wire conductor 10 is preferably formed so that the space factor R is 87.5% or more, more preferably 89.0% or more, and even more preferably 91.5% or more.

[0017] Here, the term "space factor" in this specification refers to the proportion of the cross section of the concentric stranded wire 13 that is occupied by the center wire 14 and the multiple strands 15, 16. The space factor R can be expressed as R=A / B, where A is the total cross-sectional area of ​​the center wire 14 and the multiple strands 15, 16, and B is the (conceptual maximum) cross-sectional area of ​​the compressed stranded wire conductor 10 when it is assumed that the inside of the compressed stranded wire conductor 10 is completely filled with the center wire 14 and the multiple strands 15, 16.

[0018] [Power cable manufacturing method] An example of a method for manufacturing the power cable 1 will be described below with reference to FIGS. In the following description, it is assumed that the center wire 14 and the plurality of wires 15, 16 are made of the same wire having a wire diameter a, as shown in FIG.

[0019] First, a first twisting machine (e.g., a bobbin) is used in a first step to twist a plurality of wires 15 around a central wire 14. This first step forms a central stranded wire 11a before compression (see FIG. 2). If the outermost diameter of the central stranded wire 11a is b, then b = 3a.

[0020] Next, a second step is performed in which the central strand 11a is compressed using a first compressor (e.g., a die). This second step forms the compressed central strand 11b (see FIG. 3). If the outermost diameter of the central strand 11b is c and the compression ratio of this step is P1, then P1 can be expressed as P1 = ((bc) / c) × 100. Here, the "compression ratio" in this specification refers to the compression ratio required to make the outermost diameter of the twisted wires (central strand 11a, concentric strand 13) a desired diameter.

[0021] Next, a third step is performed in which a second twisting machine (e.g., a bobbin) twists multiple strands 16 around the central strand 11b. This third step forms a concentric strand 13 (see FIG. 4). If the outermost diameter of the concentric strand 13 is d, then d can be expressed as d = c + 2a.

[0022] Next, a fourth step is performed in which the concentric stranded wire 13 is compressed using a second compression device (e.g., a die). This fourth step forms the compressed stranded conductor 10 (see FIG. 5). When the outermost diameter of the compressed stranded conductor 10 is e and the compression ratio in this step is P2, P1 can be expressed as P1 = ((de) / e) × 100.

[0023] Here, if the average compression ratio of the compression ratio P1 in the second step and the compression ratio P2 in the fourth step is P, then P can be expressed as P = (P1 + P2) / 2. Because the average compression ratio P has a logarithmic relationship with the space factor R, the space factor R can be formed to fall within the above range by increasing or decreasing the average compression ratio P. In other words, by adjusting the average compression ratio P, the compressed stranded conductor 10 is formed so that the space factor R is 87.0% or more and 95.0% or less.

[0024] In this example, the upper limit of the space factor R of the compressed stranded conductor 10 is set to 95.0% or less, but this is due to the convenience of compression technology. In other words, due to the convenience of compression technology, the upper limit of the space factor R should be set to 100% if possible.

[0025] Next, a fifth step is performed in which an insulating coating 20 is applied to the compressed stranded conductor 10 using an extruder or the like. The power cable 1 is completed by this fifth step (see FIG. 1). The first to fifth steps performed as described above are performed, for example, as a series of steps.

[0026] [Relationship between space factor, conductor resistance, and allowable current] The relationship between the space factor, conductor resistance, and allowable current will be explained below with reference to Tables 1 to 6. As the power cable 1, a JISC3605:2002 600V polyethylene cable is used as an example.

[0027] Table 1 is a table summarizing the values ​​when the cable size is 60 sq. Table 2 is a table summarizing the values ​​when the cable size is 100 sq. Table 3 is a table summarizing the values ​​when the cable size is 150 sq. Table 4 is a table summarizing the values ​​when the cable size is 200 sq. Table 5 is a table summarizing the values ​​when the cable size is 250 sq. Table 6 is a table summarizing the values ​​when the cable size is 325 sq. Note that the "nominal diameter" in the tables refers to the diameter of the compressed stranded conductor 10.

[0028] Furthermore, the "target allowable current" in the table is a value set so that each cable size can be used for a circuit breaker (hereinafter referred to as the "first circuit breaker") with a capacity one step higher than the circuit breaker (earth leakage circuit breaker, load circuit breaker, etc.) normally used for that cable size. In other words, if the allowable current of a cable (hereinafter referred to as the "first cable") exceeds the target allowable current, the first cable can be used for a first circuit breaker that would normally require a larger cable size to accommodate that. The "target allowable current" is a value set for this purpose.

[0029] [Table 1]

[0030] [Table 2]

[0031] [Table 3]

[0032] [Table 4]

[0033] [Table 5]

[0034] [Table 6]

[0035] It can be seen from Tables 1 to 6 that, regardless of the cable size, as the space factor R increases, the conductor resistance decreases and the allowable current increases.

[0036] Furthermore, according to Table 1, the target allowable current is exceeded when the space factor R is 87.5%. For this reason, it is preferable that the space factor R of the compressed stranded conductor is 87.5% or more.

[0037] Furthermore, according to Table 5, the target allowable current is exceeded when the space factor R is 89.0%. For this reason, it is more preferable that the space factor R of the compressed stranded conductor is 89.0% or more.

[0038] Furthermore, according to Tables 2 and 3 (including Tables 1, 4, and 5 to 7), the target allowable current is exceeded when the space factor R is 91.5%. Therefore, it is more preferable that the space factor R of the compressed stranded conductor is 91.5% or more.

[0039] In this way, according to the present invention, the conductor resistance can be reduced without increasing the cable size. That is, according to the present invention, the conductor resistance is reduced, which increases the allowable current and increases the number of applicable circuits.

[0040] Furthermore, according to the present invention, the conductor resistance is reduced, thereby increasing the length of the cable redundancy that satisfies the allowable voltage drop value in the interior wiring regulations.

[0041] [Differences between power cables and communication cables] The difference between power cables and communication cables is as follows: Communication cables do not normally carry large currents, so they tend to be small in size (thin in diameter). For this reason, compression wires are not used in communication cables due to standards and other reasons. This is one of the differences. In other words, the present invention is useful for power cables.

[0042] [Features of the compressed stranded conductor and power cable according to the present embodiment] Here, the features of the compressed stranded conductor and the power cable according to the present invention will be briefly summarized and listed below.

[0043] [1] a central strand (11) in which a plurality of wires (15) are concentrically stranded around a central wire (14); an outer layer strand (12) in which a plurality of wires (16) are concentrically stranded around the central strand (11); A compressed stranded conductor (10) comprising: a concentric stranded wire (13) consisting of the central stranded wire (11) and the outer-layer stranded wire (12) is compressed, and a space factor (R), which is the ratio of the central wire (14) and the plurality of strands (15, 16) to the cross section of the concentric stranded wire (13), is 87.0% or more; Compressed stranded conductor (10).

[0044] [2] The compressed stranded conductor (10) according to the above [1], The space factor (R) is 95.0% or less. Compressed stranded conductor (10).

[0045] [3] The compressed stranded conductor (10) according to [1] or [2] above, and an insulating coating (20) covering the compressed stranded conductor. Power cable (1).

[0046] According to the above configurations [1] to [3], the space factor is 87.0% or more (95.0% or less), which reduces the conductor resistance and increases the allowable current. In other words, the conductor resistance can be reduced without increasing the cable size. [Explanation of symbols]

[0047] 1 Power cable 10 Compressed stranded conductor 11 center strand 12 Outer layer strands 13 Composite stranded wire 14 Center line 15,16 Wire 20 Insulation coating R Space factor

Claims

1. a central stranded wire in which a plurality of wires are concentrically stranded around a central wire; an outer layer stranded wire formed by twisting a plurality of wires concentrically around the central stranded wire; A compressed stranded conductor comprising: a concentric stranded wire consisting of the central stranded wire and the outer layer stranded wire is compressed, and a space factor, which is the ratio of the central wire and the plurality of strands to the cross section of the concentric stranded wire, is 87.0% or more; Compressed stranded conductor.

2. The compressed stranded conductor according to claim 1, The space factor is 95.0% or less. Compressed stranded conductor.

3. The compressed stranded conductor according to claim 1 or 2; an insulating coating covering the compressed stranded conductor, Power cable.

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