JP2006087251A - Method of stringing aerial cable - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of stringing an aerial cable in which a work for supporting the aerial cable fixedly by forming an offset portion between supporting poles can be simplified. <P>SOLUTION: A binding wire 3 is stretched between supporting poles 2, a roller 4 is suspended from the binding wire 3, an aerial cable 1 is passed through the roller 4 and the aerial cable 1 is pulled, and then the aerial cable 1 is supported fixedly on the supporting pole 2. In such a method for stringing an aerial cable, the aerial cable 1 is strung under such a state as the length L of the aerial cable 1 located between the supporting poles 2 when the aerial cable 1 is passed through the roller 4 and strung becomes the sum of the length when the aerial cable 1 secured to the supporting pole has a predetermined degree of slackening and the length required for forming an offset portion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for laying overhead cables such as power cables.

  Generally, in order to lay an aerial cable such as a power cable, as described in Patent Document 1, a support line is stretched between power poles, and a gold wheel (roller) is attached to each power pole or support line. The aerial cable drawn from the cable drum is pulled through the gold wheel (roller), and then the aerial cable is supported and fixed to the utility pole.

JP-A-9-289714

  However, the above-described method for laying an aerial cable has a problem that when the aerial cable pulled through a metal wheel (roller) is supported and fixed to a utility pole, the aerial cable may have to be moved greatly in the line direction. . That is, for example, when the length of an aerial cable pulled between utility poles to be supported and fixed is short, pull the aerial cable pulled between adjacent utility poles and use the aerial cable as a utility pole. On the other hand, if the length of the overhead cable pulled between the utility poles to be supported and fixed is long, the overhead cable must be sent out between adjacent utility poles. Arise. Thus, there is a problem that it is very troublesome to draw an aerial cable pulled between adjacent power poles or send an aerial cable between adjacent power poles.

  The present invention provides an aerial cable laying method that can easily lay an aerial cable without the need to move the aerial cable in the track direction when the aerial cable pulled between the support columns is supported and fixed to the support column. It is.

  According to the first aspect of the present invention, a support line is stretched between support columns, a roller is suspended on the support line, an aerial cable is extended through the aerial cable to the roller, and then the aerial cable is supported and fixed to the support column. In the laying method of the aerial cable, the length of the aerial cable located between the support columns is the sum of the length required to form the offset portion and the length required to form the offset portion when the aerial cable is fixed to the support column. This is a method for laying an aerial cable, characterized in that the aerial cable is extended in this state, and then the aerial cable is supported and fixed by forming an offset portion on a support post.

  According to the second aspect of the present invention, when an aerial cable is supported and laid by a messenger wire along the aerial cable, the length required for forming the offset portion between the support pillars is determined by the extension amount of the aerial cable (α1 2. The method for laying an aerial cable according to claim 1, wherein it is determined in consideration of the amount of extension of the messenger wire (α2 × t2 × L) in addition to (xt1 × L). Where α1 is the linear expansion coefficient of the cable, α2 is the linear expansion coefficient of the messenger wire, t1 is the temperature change of the overhead cable, t2 is the temperature change of the messenger wire, and L is 1/2 of the length between the support columns.

  Furthermore, the invention described in claim 3 is the aerial cable laying method according to claim 1, wherein the roller has a shape for sandwiching the aerial cable.

The present invention has the following effects.
In the method for laying an aerial cable according to claim 1, the length of the aerial cable positioned between the support columns when the aerial cable is extended through the roller through the aerial cable is determined when the aerial cable is fixed to the support column. Since the wire is extended in a state that is the sum of the slack length and the length required for forming the offset portion, the overhead cable is pulled between the support columns when the offset portion is formed and supported between the support columns. It is sufficient to use only the length of cable. Therefore, it is not necessary to use a cable that is pulled between adjacent support columns as in the prior art or to send out a cable between adjacent support columns. Therefore, it is possible to easily perform the work of supporting and fixing the overhead cable by forming the offset portion between the support columns.

  Further, in the aerial cable laying method according to claim 2, when the aerial cable is supported by a messenger wire along the aerial cable and laid, the length required for forming the offset portion between the support columns is set to the extension of the aerial cable. Since the amount of extension of the messenger wire (α2 × t2 × L) is determined in addition to the amount of extraction (α1 × t1 × L), the shape of the offset portion can be reduced in size.

  Moreover, since the installation method of the aerial cable which concerns on Claim 3 has the shape which a roller pinches | interposes an aerial cable, it can be pulled in the state which hold | maintained the aerial cable in the fixed shape.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an aerial cable laying method according to the present invention. In the figure, 1 is an aerial cable, 2 is a support column, 3 is a support line, and 4 is a roller.

  As shown in FIG. 2, the aerial cable 1 bundles three single-core cables 11, messenger wires 12 are placed along the bundled single-core cables 11, and the messenger wires 12 and the single-core cables 11 are lashing wires. 13 is an integrated structure.

  As shown in FIG. 3, the roller 4 has a structure provided with a support wire attachment rotating part 41 and an aerial cable support part 42. The aerial cable support part 42 has cylindrical rollers arranged in a V shape so as to sandwich the aerial cable 1. If the aerial cable support part 42 is formed in a V shape so as to sandwich the aerial cable 1 in this way, the positions of the single-core cable 11 and the messenger wire 12 even when the aerial cable is pulled through the bent part. There is an advantage that both can be always kept in a constant state without changing.

Next, a method for laying the overhead cable having the above configuration between the support columns 2 will be described with reference to FIGS.
First, as shown in FIG. 1, a support wire 3 is wired between the support columns 2, and the support wire 3 is fixed to the support column 2 with a fixing metal 5.

  Next, the roller 4 is suspended from the support wire 3. That is, the support line attachment rotating part 41 of the roller 4 is attached to the support line 3.

  Next, the pulling wire 6 is connected to the tip of the aerial cable, and the pulling wire 6 is connected to the winch 70 through the aerial cable support 42 of the roller 4.

  Next, the winch 70 is driven and the pulling wire 6 is wound up. As a result, the aerial cable 1 is sequentially pulled through the aerial cable support portion 42 of the roller 4, and the aerial cable 1 is wired between the support columns 2.

  In the embodiment of FIG. 1, an operation of bundling three single-core cables 11, an operation of placing the messenger wire 12 along the bundled single-core cables 11, and a lashing wire between the messenger wires 12 and the single-core cables 11. 13 is performed at the laying site.

  Finally, as shown in FIG. 4, the messenger wire 12 of the aerial cable 1 is fixed to the support column 2 by the fixing bracket 5. At this time, the single-core cable 11 is separated from the messenger wire 12 in the vicinity of the support pillar 2 to form the offset portion 7. In FIG. 4, reference numeral 10 denotes a separation fitting attached at a separation position of the single-core cable 11 and the messenger wire 12. The separation fitting 10 supports a single core cable so that the single core cable 11 can move in the line direction.

  The feature of the present invention is that, as shown in FIG. 1, the length L of the aerial cable between the support columns 2 when the aerial cable 1 is extended to the roller 4 through the aerial cable 1 is shown in FIG. As described above, when the aerial cable is fixed between the support pillars 2, the cable is extended so as to be the sum of a length A that has a predetermined sag d and a length B that is required for forming the offset portion. That is, L = A + B.

  The length B required for forming the offset portion between the support columns is the length b1 required for forming the offset portion in one support column 2 when the offset portion 7 is formed on each support column 2 as shown in FIG. And the length b2 required for forming the offset portion in the other support pillar 2. That is, B = b1 + b2. Further, the length B (b1, b2) required for forming the offset portion between the support pillars is supported by forming the offset portion having a predetermined shape from the point where the single-core cable 11 is separated from the separation metal fitting 10. This is the length up to the central axis of the pillar 2. The length of the entire offset portion is, for example, the length required for forming the offset portion between the support pillars adjacent to the length of b1 or b2, for example, the same length as b1 or b2.

  In addition, when the offset part 7 is formed only in one side of the support pillar 2, the length B required for offset is only b1 or b2. That is, B = b1 or B = b2.

  Wired so that the length L of the overhead cable between the support columns 2 is the sum of the length A required to form the offset portion and the length B required for forming the offset portion when the length between the support columns 2 is fixed. In order to do so, as shown in FIG. That is, since the distance between the support pillars 2 and the length L (L = A + B) of the overhead cable extending between the support pillars 2 are known, if the slackness D is managed and extended, the support pillars The cable can be extended so that the length L of the overhead cable between the two is constant.

  As described above, the length of the aerial cable located between the support columns when the aerial cable is extended is a length that is a predetermined slack when the aerial cable is fixed to the support column, and a length required for forming the offset portion. When the aerial cable 1 pulled between the support columns 2 is supported and fixed with a predetermined slackness and an offset portion between the support columns 2 by extending the wire in a state that becomes the sum of the support columns 2. It can be supported and fixed using only an aerial cable pulled between them. Therefore, the overhead cable can be easily supported and fixed by forming an offset portion between the support columns 2 with a predetermined slackness.

For example 50m in length between the support posts, using aerial cable of 77kV 60mm ^2, is provided an offset portion on each side of the support column, if the overhead cable as the final laying sag is 3% support fixed The length A of the aerial cable having a sag of 3% is 47886 mm, and the length B required for offset is 2324 mm (1162 mm × 2). Therefore, the length of the aerial cable when the aerial cable 1 is pulled between the support columns is required to be 50210 mm, and the slackness D of the aerial cable between the support columns at that time is 7.96%.

  That is, if the slackness D of the aerial cable between the support columns is determined to be 7.96% in advance, the aerial cable is connected to the support column using only the aerial cable in the support column. It can be supported and fixed at a degree of 3% and a predetermined offset shape.

By the way, when the overhead cable 1 is supported by the messenger wire 12 and laid as shown in FIG. 4, the length B required for forming the conventional offset portion takes into account the amount of cable extension (α1 × t1 × L). It was decided. For example, as described above, when a cable having a length between support columns of 50 m and 77 kV 60 mm ² is used, the cable extension amount (α1 × t1 × L) is 20 × 10 ⁻⁶ × 65 ° C. × 25 m = 32.5 mm. However, α1 is the linear expansion coefficient of the cable, 20 × 10 ⁻⁶ (1 / ° C.), t1 is the temperature, 65 ° C., and L is 1/2 of the length between the support columns and 25 m. The cable extension amount (α1 × t1 × L) is an extension amount of half the length between the support columns.

  Conventionally, the offset portion is formed so that the overhead cable of the offset portion does not fall below the allowable bending diameter even if the amount of extension of the overhead cable occurs. That is, as shown in FIG. 5, the conventional offset portion is formed such that the length B required for the offset is 1162 mm, the minimum offset width Z is 300 mm, and the minimum offset length Y is 1109 mm.

  However, when an aerial cable is supported by a messenger wire and laid, when determining the extension amount of the aerial cable (α1 × t1 × L), the extension amount of the messenger wire (α2 × t2 × L) is also considered. In designing the offset part, in addition to the extension amount of the overhead cable, the extension amount of the messenger wire (α2 x t2 x L) is also considered, and the extension amount of the overhead cable in the offset part is the extension of the overhead cable. It has become clear that it is preferable to obtain the amount (α1 × t1 × L) -messenger wire extension amount (α2 × t2 × L).

For example, when using a cable having a length between support columns of 50 m and 77 kV 60 mm ² as described above, the amount of cable extension (α1 × t1 × L) is 20 × 10 ⁻⁶ × 65 ° C. × 25 m = On the other hand, the amount of extension of the messenger wire (α2 × t2 × L) is 11.5 × 10 ⁻⁶ × 65 ° C. × 25 m = 18.7 mm. Therefore, the amount of extension of the overhead cable at the offset portion is 32.5 mm-18.7 mm = 13.8 mm.

  Considering the length of the overhead cable that extends to the one offset section as described above, as well as the extension amount of the messenger wire, in addition to the extension amount of the overhead cable, the extension amount of the overhead cable at the offset section is reduced. . A reduction in the amount of extension of the overhead cable at the offset portion means that bending applied to the overhead cable at the offset portion is reduced. For this reason, even if the shape of the offset portion is reduced, there is no possibility that harmful bending stress is generated in the overhead cable of the offset portion. In the above case, it was confirmed that there was no problem even if the minimum offset width Z was 200 mm, the minimum offset length Y was 825 mm, and the length B required for the offset was 857 mm.

  In the above-described embodiment, three single-core cables are bundled as an aerial cable, a messenger wire is placed along the bundled single-core cables, and the messenger wire and the single-core cable are integrated with a lashing wire. Although used, the structure of the aerial cable is not particularly limited, and for example, it may be one without a messenger wire.

The schematic block diagram of the installation method of the aerial cable which concerns on this invention. Sectional drawing which shows one Embodiment of an aerial cable. Explanatory drawing of a roller. Explanatory drawing of the installation state of an aerial cable. Explanatory drawing of an offset part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aerial cable 2 Support pillar 3 Support line 4 Roller 5 Fixing metal fitting 6 Pulling wire 7 Offset part 11 Single core cable 70 Winch

Claims (3)

  In an aerial cable laying method in which a support line is stretched between support columns, a roller is suspended on the support line, an aerial cable is extended through the aerial cable to the roller, and then the aerial cable is supported and fixed to the support column. The length of the aerial cable located between the support columns is extended in a state where the length becomes a predetermined slack when the aerial cable is fixed to the support column and the length required for forming the offset portion. Then, an aerial cable laying method characterized in that the aerial cable is offset and formed on a support column to be supported and fixed.   When laying an aerial cable supported by a messenger wire along the aerial cable, the length required for forming the offset portion between the support columns is set in addition to the amount of extension of the aerial cable (α1 × t1 × L). The method for laying an aerial cable according to claim 1, wherein the method is determined in consideration of a wire extension amount (α2 × t2 × L). Where α1 is the linear expansion coefficient of the cable, α2 is the linear expansion coefficient of the messenger wire, t1 is the temperature change of the overhead cable, t2 is the temperature change of the messenger wire, and L is 1/2 of the length between the support columns.   The method for laying an aerial cable according to claim 1, wherein the roller has a shape for sandwiching the aerial cable.

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