JP6102443B2 - Power cable - Google Patents

Description

  The present invention relates to a power cable, and more particularly to a power cable used as an underground transmission line for high-voltage power.

  The power cable includes, for example, a conductive portion, an insulating layer that covers the outer periphery of the conductive portion, and a coating layer that covers the outer periphery of the insulating layer. Such a power cable is used as, for example, an underground transmission line for high-voltage power, and is laid in a limited space such as in a pipeline. When power is supplied to the conductive portion, the power cable extends in the axial direction due to thermal expansion and contraction. The amount of extension that cannot be absorbed in the restricted space in the pipeline is absorbed by the bending deformation of the power cable that extends into the manhole provided in the middle of the pipeline.

  Further, when there is an inclination or the like in the pipeline, the power cable may slide down due to this thermal expansion and contraction. Such slipping is greatly influenced not only by the mass, length, and temperature change of the power cable, but also by the linear expansion coefficient. That is, the power cable slides when the region where the temperature change width is large and the thermal expansion / contraction does not occur, that is, the immovable region disappears. For this reason, an anti-skid device or the like that holds the power cable using a spring or weight may be attached to the power cable.

  The amount of extension of the power cable is cross-linked polyethylene insulated PVC sheathed cable, which has become the mainstream nowadays compared to the oil-filled paper insulated power cable (OF cable: Oil Filled Cable) that has been used in the past. CV cable) is larger.

  For this reason, for example, when there is a reason for renewal such as a system change of an existing line where an OF cable has been used, an accident response or aged disposal, etc., there is room to absorb the amount of extension of the CV cable in the manhole size etc. There may not be. In such a case, the actual situation is that it has to be updated with an OF cable as before.

  Therefore, in Patent Document 1, for example, a linear body is wound in a spiral shape on the circumference of the power cable body, and a snake-like deformation is assisted along the winding of the linear body. The extension to the snake shape suppresses the extension in the axial direction and reduces the extension amount from the pipe line to the human hole.

  For example, in Patent Document 2, a segment or a part of a stranded wire constituting a copper conductor is combined with another conductor having a bending rigidity different from that of the copper conductor, such as aluminum. In such a power cable, the conductor is helically deformed as the temperature rises due to energization, so that the extension in the axial direction is suppressed and the amount of extension from the pipeline into the human hole is reduced.

Japanese Patent Laid-Open No. 03-102713 Japanese Patent Laid-Open No. 02-139806

  However, as in Patent Document 1, for example, a snake shape is not easily obtained simply by winding a linear body around a power cable body. Therefore, complicated additional measures such as applying tension to the linear body and forming the linear body so as to periodically have thick and thin portions in the length direction are required. Moreover, since a part of the outer shape is spiral and the cross section of the power cable is not circular, cable processing and laying are difficult.

  For example, as in Patent Document 2, if a material such as aluminum having a different electrical resistance from the copper conductor is used for a segment or a part of the stranded wire, the electrical resistance as a whole is increased.

  Moreover, in order to suppress the slipping of the power cable due to an inclination in the pipe line or the like, if a slipping prevention device using a spring or a weight is attached to the power cable as described above, the size of the human hole becomes large.

  An object of the present invention is to provide a power cable that can reduce the amount of extension with a simple structure.

According to a first aspect of the invention,
A conductive part;
An insulating layer covering the outer periphery of the conductive portion;
A coating layer covering the outer periphery of the insulating layer,
In the conductive part,
There is provided a power cable in which a wire made of a material having a Young's modulus and a smaller linear expansion coefficient than that of the material constituting the conductive portion is provided in the axial direction of the conductive portion.

According to a second aspect of the invention,
A hollow portion extending in the axial direction of the conductive portion is provided in the central portion of the conductive portion,
The power cable according to the first aspect in which the wire provided in the conductive portion is inserted into the hollow portion is provided.

According to a third aspect of the invention,
The conductive portion is a combination of a plurality of segments,
The power cable according to the first aspect is provided in which the wire provided in the conductive portion is disposed in each of the segments.

According to a fourth aspect of the invention,
The electric power cable according to a third aspect is provided in which the wire is disposed in each segment so that the wire is located in the center in the segment.

According to a fifth aspect of the present invention,
The electric power cable according to a third aspect is provided in which the wire is disposed in each segment so that each wire is located in the vicinity of an outer edge portion in the segment.

According to a sixth aspect of the present invention,
The power cable according to any one of the first to fifth aspects is provided in which at least a part of an outer surface of a wire provided in the conductive portion is in contact with the conductive portion.

According to a seventh aspect of the present invention,
The power cable according to any one of the first to sixth aspects is provided in which at least a part of the conductive portion is meandered when the conductive portion is energized.

According to an eighth aspect of the present invention,
The conductive part is a copper conductor;
The power cable according to any one of the first to seventh aspects, in which the wire provided in the conductive portion is an invar wire.

According to a ninth aspect of the present invention,
The insulating layer is composed of cross-linked polyethylene,
The power cable according to any one of the first to eighth aspects, in which the covering layer is made of vinyl chloride.

  ADVANTAGE OF THE INVENTION According to this invention, the electric power cable which can reduce the amount of extension with a simple structure is provided.

It is sectional drawing orthogonal to the axial direction of the power cable which concerns on one Embodiment of this invention. It is sectional drawing orthogonal to the axial direction which shows the structural example of the power cable which concerns on one Embodiment of this invention. (A) is sectional drawing orthogonal to the axial direction of the power cable which concerns on the Example of this invention, and sectional drawing of an axial direction, (b) is sectional drawing orthogonal to the axial direction of the CV cable which concerns on a comparative example. (C) is sectional drawing orthogonal to the axial direction of OF cable which concerns on another comparative example, and sectional drawing of an axial direction. It is a schematic diagram which shows the state of the installation of the power cable used as an underground power transmission line.

<One Embodiment of the Present Invention>
(1) Structure of Power Cable A power cable according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view orthogonal to the axial direction of the power cable 1 according to the present embodiment.

  As shown in FIG. 1, the power cable 1 according to this embodiment includes a conductive portion 10, an insulating layer 20 that covers the outer periphery of the conductive portion 10, and a covering layer 30 that covers the outer periphery of the insulating layer 20. Prepare. In the conductive part 10, a wire 40 made of a material having a Young's modulus and a smaller linear expansion coefficient than the material constituting the conductive part 10 is provided.

  At this time, for example, the conductive portion 10 is a copper conductor, the insulating layer 20 is made of cross-linked polyethylene, the covering layer 30 is made of vinyl chloride, the wire 40 is an invar wire, and the power cable 1 is cross-linked polyethylene insulated vinyl sheath cable (Crosslinked polyethylene). Insulated PVC sheathed cable (CV cable) can be configured as a power cable in which an invar wire is combined.

  That is, the conductive portion 10 is a copper conductor or the like formed by combining a plurality of segments 10s made of pure copper (C) or a copper alloy and having a cross-sectional shape such as a trapezoidal shape or a fan shape. At this time, each segment 10s may be formed by twisting a plurality of strands made of pure copper, copper alloy, or the like. Moreover, each segment 10s may be combined so that it may become two layers of an inner layer and an outer layer, or may be combined so that it may become more than that several layers. A hollow portion 10 w extending in the axial direction of the conductive portion 10 is provided at the center of the combined (innermost layer) segment 10 s, that is, at the central portion of the conductive portion 10.

  The wire 40 is inserted into the hollow portion 10 w and is inserted in the axial direction of the conductive portion 10. At this time, it is preferable that the wire 40 is inserted into the hollow portion 10w without a gap, and at least a part of the outer surface of the wire 40 is in contact with the conductive portion 10 constituting the inner wall of the hollow portion 10w. Moreover, at this time, the wire 40 may be comprised only from one piece, or may be comprised in the state bundled by twisting or compressing several strands. The wire 40 is made of, for example, an invar wire or a carbon composite wire made of stainless steel obtained by adding a predetermined amount of nickel (Ni) to iron (Fe). Such a material has, for example, a Young's modulus larger than that of the copper conductor constituting the conductive portion 10 and a smaller linear expansion coefficient.

  The power cable 1 configured as described above is laid in, for example, a pipeline provided in the ground. For example, a cable connecting portion for connecting the power cables 1 to each other is installed in a human hole provided at a predetermined position of the pipeline. The power cables 1 are connected by compressing the wires 40 provided in the power cable 1.

(2) Action of power cable The power cable 1 according to the present embodiment has the following action.

  That is, when the conductive portion 10 is energized, the conductive portion 10 extends due to the temperature rise. On the other hand, the wire 40 inserted into the hollow portion 10 w has a smaller amount of extension than the conductive portion 10. For this reason, the conductive part 10 absorbs its extension amount by bending to meander with a predetermined period or an irregular period with respect to the axial direction. At this time, the snake shape may be taken so that the insulating layer 20, the covering material 30 and the like provided around the conductive portion 10 follow the conductive portion 10, and as a result, the entire power cable 1 may take the snake shape.

  Alternatively, the power cable 1 is shaped so as to be balanced between the conductive portion 10 having a small extension amount in the axial direction and the wire 40 having a large extension amount in the axial direction. The amount of extension of may be absorbed. Thus, when the power cable 1 takes a balanced shape so as to absorb the amount of extension, the power cable 1 may not have a snake shape.

  Further, as described above, if the wire 40 having a smaller linear expansion coefficient than that of the constituent material of the conductive portion 10 is used and, for example, as described above, the wire 40 and the conductive portion 10 are brought into contact with each other, the elongation is increased. The amount to be taken out can be further reduced, which is more preferable. In such a configuration, it is considered that the extension amount is reduced mainly due to friction between the wire 40 and the conductive portion 10. In such a case, it is considered that there is an effect of suppressing the extension force at the terminal of the power cable 1.

  The amount of extension at both ends of the cable that could not be absorbed by the above is absorbed when the power cable 1 is bent, that is, offset, in the human hole where the cable connection portion is installed. In the power cable 1, the amount of extension into the human hole is reduced.

  Thereby, the amount of bending deformation of the power cable 1 extending into the human hole, that is, the so-called offset deformation amount can be reduced. Usually, in a power cable having an outer diameter D, the allowable bending radius is, for example, 10D or more. In the power cable 1 of this embodiment, the amount of offset deformation can be kept small, and the amount of deformation (bending amount) equal to or larger than the allowable bending radius can be maintained in a small-sized human hole.

  Moreover, in the power cable 1, the extension amount of the whole power cable 1 is reduced, and even if the temperature change width increases, a region where thermal expansion and contraction does not occur, that is, a so-called immovable region can be sufficiently secured. . This makes it difficult for the power cable 1 to slide down even in an inclined pipeline. Therefore, for example, it is not necessary to attach an anti-skid device or the like that suppresses slipping using a spring, a weight, or the like in the human hole to the power cable 1, and laying is possible even if the human hole size is small.

  For example, a conventional CV cable has a larger amount of extension than an OF cable. For this reason, it will become an offset bend radius which falls below an allowable bend radius in a human hole by extension at the time of energization. In the case of an inclined pipe, sliding is likely to occur. Thus, it is often difficult to lay CV cables on existing lines for OF cables. In addition, when a new line for a CV cable is provided, the size of the manhole must be enlarged so that the bending radius is not less than the allowable bending radius when energized, and a slip prevention device or the like can be installed.

  However, in the power cable 1 according to the present embodiment, the amount of extension is equal to or less than that of the OF cable. Sliding in the pipeline is unlikely to occur. Further, the cross-sectional area of the conductive portion 10 of the power cable 1 can be configured to be substantially equal to, for example, an OF cable having a hollow tube serving as an oil path in the conductive portion. Therefore, compared with an OF cable, it can have the same or more power transmission capacity.

  Thus, the power cable 1 according to this embodiment can be easily laid on an existing line for an OF cable. By replacing the existing OF cable, for example, the oil supply facility can be eliminated from the inside of the track. Moreover, when providing a new track, it is not necessary to increase the size of the manhole. Thus, the power cable 1 according to the present embodiment is advantageous in terms of line design and line maintenance.

(3) Power Cable Manufacturing Method The power cable 1 according to this embodiment can be manufactured by the following manufacturing method.

  That is, first, a strand such as an invar wire is prepared, and this is used as the wire 40. Alternatively, a stranded wire obtained by twisting a plurality of such strands is used as the wire 40. The conductive portion 10 in which the wire 40 is inserted into the hollow portion 10w is formed by twisting one or more segments 10s made of pure copper or a copper alloy around the wire 40, for example. As described above, each segment 10s can be formed by twisting a plurality of strands made of, for example, pure copper or copper alloy so as to have a cross-sectional shape such as a trapezoidal shape or a fan shape.

  Thereafter, for example, an insulating layer 20 made of crosslinked polyethylene and a coating layer 30 made of vinyl chloride are formed on the outer periphery of the conductive portion 10 by extrusion molding or the like. As described above, the power cable 1 according to this embodiment is manufactured.

(4) Modified Example of Present Embodiment Next, a power cable according to a modified example of the present embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view orthogonal to the axial direction illustrating a configuration example of a power cable according to an embodiment of the present invention. In FIG. 2, components that are substantially the same as those described in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

  In the above-described embodiment, the insertion position of the wire rod 40 is the central portion of the conductive portion 10, but the insertion positions of the wire rods 41 and 42 are different in the power cables 1a and 1b according to the modification.

  That is, as shown in FIG. 2A, in the cable 1a according to the modified example, the conductive portion 11 is formed by combining a plurality of segments 11s, and the wire 41 is disposed at the center of each segment 11s. Has been.

  Thus, it can suppress that the meandering of the electroconductive part 11 arises because each wire 41 is arrange | positioned equally in the center part of each segment 11s. Therefore, for example, in the pipe line that extends in a straight line, the conductive portion 11 or the power cable 1a has a snake shape that is substantially along the pipe line.

  The power cable 1a can be manufactured, for example, by the following method. That is, first, a strand such as an invar wire or a stranded wire obtained by twisting a plurality of strands is used as a wire 41, and one or more layers of a strand made of pure copper or a copper alloy are twisted around the wire 41. Thus, each segment 11s is manufactured. Thereafter, the power cable 1a is manufactured by combining the segments 11s in a predetermined number and in a predetermined arrangement, and compressing the whole from the outermost layer side before or after forming the insulating layer 20 and the covering layer 30. .

  Further, as shown in FIG. 2B, in the cable 1b according to another modification, the conductive portion 12 is formed by combining a plurality of segments 12s, and a plurality of segments are provided near the outer edge of each segment 12s. Wires 42 are respectively arranged. Like each segment 11s of the power cable 1a, each segment 12s of the power cable 1b is also configured by twisting together a strand such as an invar wire and a strand made of pure copper or a copper alloy, for example. The arrangement of the wires 42 in the cross section shown in FIG. 2B is merely an example. That is, the position of each wire 42 changes while undulating within the segment 12s. Therefore, depending on which cross section of the power cable 1b is cut out, the outer edge side in contact with the insulating layer 20, the outer edge side in contact with one adjacent segment 12s, and the outer edge side in contact with the other adjacent segment 12s in the segment 12s , And the position of each wire 42 seems to move.

  As described above, the conductive portions 12 are easy to meander by arranging each wire 42 at the outer edge of each segment 11s while changing its position. Therefore, for example, in a meandering pipeline, the conductive portion 12 or the power cable 1b can be adjusted by the arrangement of each wire 42 so as to take a snake shape along the curvature in the pipeline.

  The power cable 1b can also be manufactured by the same method as the power cable 1a. However, in this case, the wire 42 is mixed in a bundle of a plurality of strands made of pure copper or a copper alloy so as to be positioned in the vicinity of the outer edge of the segment 12s, and the wire 42 and the pure copper or copper are mixed. Twist together the strands made of an alloy or the like.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment and modification of this invention were described concretely, this invention is not limited to the above-mentioned embodiment and modification, and can be variously changed in the range which does not deviate from the summary.

  For example, in the above-described embodiment and modification, the wire rods 40, 41, and 42 are made of invar wires, but the wire rod is, for example, carbon fiber or aramid fiber such as Kevlar (registered trademark) manufactured by DuPont. You may be comprised from. As described above, any material having a Young's modulus and a smaller linear expansion coefficient than the material constituting the conductive portion can be used as a wire.

  Further, for example, the shape and number of segments, the number of layers, the arrangement, the number and arrangement of inserted wires described in the above-described embodiments and modifications are merely examples, and are not limited thereto.

  Further, for example, in the above-described embodiment and modification, the power cable 1 in which the wire 40, 41, 42 such as the invar wire is combined with the CV cable has been described. However, this configuration is applied to the OF cable and other cables. Also good.

  Next, examples according to the present invention will be described together with comparative examples.

(1) Calculation of extension amount First, theoretical values such as the extension amount were calculated for the power cables according to the example and the comparative example. FIG. 3 shows the specifications of the power cable used for calculating the theoretical value.

  3A is a cross-sectional view orthogonal to the axial direction of the power cable 2 according to the embodiment of the present invention and an axial cross-sectional view, and FIG. 3B is a cross-sectional view of the CV cable 3 according to the comparative example. It is sectional drawing orthogonal to an axial direction, and sectional drawing of an axial direction, (c) is sectional drawing orthogonal to the axial direction of OF cable 4 which concerns on another comparative example, and sectional drawing of an axial direction.

  As shown in FIG. 3A, the power cable 2 according to the embodiment is configured as a power cable in which a wire 240 is inserted into a hollow portion 210w provided in the central portion of the conductive portion 210.

  That is, the power cable 2 includes a conductive portion 210 composed of a plurality of copper segments, an insulating layer 220 made of crosslinked polyethylene, and a coating layer 230 made of vinyl chloride. Further, a wire 240 made of Invar stranded wire is provided in the hollow portion of the conductive portion 210. In addition, a binder 221 made of metal tape and insulating paper such as kraft paper is provided on the outer periphery of the conductive portion 210. Part of the insulating paper constituting the binder 221 is also inserted between the segments of the conductive portion 210.

  An internal semiconductive layer 222 is provided between the binder 221 and the insulating layer 220. Further, between the insulating layer 220 and the covering layer 230, an outer semiconductive layer 231, a shielding layer 232 formed by combining an annealed copper wire, a pressing tape 233, and a water shielding layer 234 are provided in this order from the insulating layer 220 side. Yes.

  As shown in FIG. 3B, the power cable 3 according to the comparative example is a general cross-linked polyethylene insulated PVC sheathed cable (hereinafter referred to as CV cable). Say).

  That is, the CV cable 3 includes a conductive portion 310 composed of a plurality of copper segments, an insulating layer 320 made of crosslinked polyethylene, and a coating layer 330 made of vinyl chloride.

  An internal semiconductive layer 322 is provided between the conductive portion 310 and the insulating layer 320. Between the insulating layer 320 and the covering layer 330, an external semiconductive layer 331, a shielding layer 332 formed by combining an annealed copper wire, a pressing tape 333, and a water shielding layer 334 are provided in this order from the insulating layer 320 side. Yes.

  As shown in FIG. 3C, the power cable 4 according to another comparative example is a general oil-immersed paper insulated power cable (OF cable: Oil Filled Cable) (hereinafter referred to as the OF cable 4). Say).

  That is, the OF cable 4 includes a conductive portion 410 made of an annealed copper wire, an insulating layer 420 made of insulating paper soaked with oil, and a coating layer 430 that is a corrosion protection layer made of vinyl chloride (PVC). In addition, a hollow tube 411 made of a zinc steel strip spiral is inserted in the center of the conductive portion 410, and an oil passage P through which oil to be impregnated into the insulating layer 420 is passed is provided. In addition, a binder 421 made of a metal tape and insulating paper such as kraft paper is provided on the outer periphery of the conductive portion 410. Part of the insulating paper constituting the binder 421 is also inserted between the segments of the conductive portion 410.

  The insulating layer 420 is covered with carbon paper 422 and 431 on the inside and outside, respectively. Further, between the outer carbon paper 431 and the coating layer 430, a shielding layer 432 made of a metal tape and carbon paper, a copper wire woven cloth tape 433, and an anticorrosion paint are applied to the outside in order from the carbon paper 431 side. A corrugated aluminum cover 434 is provided.

The theoretical value of the amount of extension was calculated for each of the cables 2 to 4 having such a structure. The examination conditions for the calculation are as follows: the conductor cross-sectional area of each cable 2 to 4 is 2000 mm ² , the distance between the cable connection parts (joints) is 500 m, and the annual temperature change in each of the conductive parts 210, 310, and 410 The width was 65 ° C., the coefficient of friction between the pipe and each cable 2 to 4 was 0.4, and the force (offset resistance) against the offset deformation of each cable 2 to 4 was 100 kgf. The Young's modulus of the power cable 2 according to the example is the same as that of the CV cable according to the comparative example.

  As shown in Table 1, the power cable 2 according to the example is considered to have the same Young's modulus of the entire cable as the CV cable 3 according to the comparative example, but the linear expansion coefficient according to the comparative example. The numerical value is equal to or less than that of the OF cable 4. Therefore, it is predicted that the extension amount can be suppressed to be equal to or less than that of the OF cable 4.

(2) Consideration about installation and sliding Next, the possibility of installation and the possibility of sliding down of the cables 2 and 3 in the predetermined pipe line are considered from the calculation result of the extension amount.

  First, the possibility of laying the cables 2 and 3 in a line form shown in FIG. FIG. 4 is a schematic diagram showing a laying state of a power cable used as an underground power transmission line.

  As shown in FIG. 4, in the line form to be considered, the length L of the pipe line 52 connecting the two human holes 51 is 500 m, and the cable connection in the human holes 51 of the cables 2 and 3 to be laid is performed. The length to the part J, that is, the offset length D was 2800 mm, and the allowable width of offset deformation in the human hole 51, that is, the offset width F was 650 mm.

In addition, the specifications of the cables 2 and 3 to be installed were based on a CV cable having an applied voltage of 154 kV and the number of conductive parts × conductor nominal sectional area of 1 × 2000 mm ² .

  When the CV cable 3 according to the comparative example is laid in such a line form, as described above, when the annual temperature change width is 65 ° C., the extension amount is 205 mm. Therefore, the offset bending radius after the extension amount is absorbed by the human hole 51 is 9.0 D with respect to the cable outer diameter D. This is below the allowable bending radius 10D of the cable. For this reason, the CV cable 3 cannot be installed in such a line form, or the line form must be expanded to a larger one.

  On the other hand, when the power cable 2 according to the embodiment is laid in such a line form, as described above, when the annual temperature change width is 65 ° C., the extension amount can be reduced to 145 mm. Therefore, the offset bending radius after the extension amount is absorbed by the human hole 51 can be set to 10.1D that is greater than the allowable bending radius 10D with respect to the cable outer diameter D. For this reason, the power cable 2 according to the embodiment can be laid also in such a line form in which it is difficult to lay a conventional CV cable. There is no need to expand the track form.

  Subsequently, the possibility of slipping when the cables 2 and 3 are laid out in a track form having a pipe length L of 600 m between manholes and a height difference of 10 m will be considered.

  When the CV cable 3 according to the comparative example is laid in such a line form, the annual temperature change width in which the sliding occurs is 53 ° C. In addition, when the annual temperature change width is 65 ° C., the sliding amount is 6.1 mm.

  On the other hand, when the power cable 2 according to the embodiment is laid in such a line form, sliding does not occur until the annual temperature change width reaches 68 ° C. Therefore, a slip-preventing device such as a restraining device that suppresses the slip-off is not necessary, and the extension of the track form is also unnecessary.

(3) Measurement of linear expansion coefficient The linear expansion coefficient of the power cable 2 according to the example was measured.

As a result, the linear expansion coefficient of the power cable 2 according to the example was 12 × 10 ⁻⁶ (1 / ° C.). Therefore, it was found that the theoretical value 20 × 10 ⁻⁶ (1 / ° C.) of the CV cable 3 according to the comparative example can be reduced by about 40%. Further, it was found that about 25% can be reduced compared with the theoretical value 16 × 10 ⁻⁶ (1 / ° C.) of the OF cable 4 according to another comparative example.

1, 1a, 1b Power cable 10, 11, 12 Conductive part 10s, 11s, 12s Segment 10w Hollow part 20 Insulating layer 30 Covering layer 40, 41, 42 Wire material

Claims (4)

A conductive part;
An insulating layer covering the outer periphery of the conductive portion;
Wherein a coating layer covering the outer periphery of the insulating layer, a power cable Ru provided with,
The conductive part is a combination of a plurality of segments formed by twisting a plurality of strands,
In the conductive part, a wire made of a material having a Young's modulus larger and a smaller linear expansion coefficient than the material constituting the conductive part is provided in the axial direction of the conductive part,
In at least a part of a plurality of cross sections orthogonal to the axial direction of the power cable,
Within the first segment of the plurality of segments, the wire is disposed only on the outer edge side in contact with the insulating layer from the center of the first segment,
In the second segment different from the first segment among the plurality of segments, the wire is arranged only on the outer edge side in contact with another adjacent segment, rather than the center of the second segment. /> Power cable characterized by that. The power cable according to claim 1, wherein the wire is arranged with its position changed while undulating in each of the plurality of segments. The conductive part is a copper conductor;
Power cable according to claim 1 or 2, characterized in that the wire provided on the conductive portion is Invar wire. The insulating layer is composed of cross-linked polyethylene,
The coating layer is a power cable according to any one of claims 1 to 3, characterized in that they are composed of vinyl chloride.

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