JP2017027716A - Optical/metal composite lead-in wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical/metal composite lead-in wire capable of decreasing building cost in a common-use cable tunnel system and also capable of promptly shifting to an optical fiber line from a metal line.SOLUTION: The optical/metal composite lead-in wire 1 includes a flat optical fiber cable 2 and at least a pair of metal cables 3 intertwisted around the optical fiber cable 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical / metal composite lead-in wire suitable for underground wiring.

  In recent years, the use of non-electric poles has been promoted for the purpose of improving cityscapes, expanding the width of sidewalks, and stably supplying power and communication services in the event of a disaster. As a method of making this non-electric pole, there is known a common wire groove method in which power lines, telephone lines, communication lines, optical cables, etc. are collectively accommodated in a common wire groove (commonly known as C.C. (See Non-Patent Document 1).

  The common wire groove type is a special part (hand hole), a body pipe that accommodates a cable that passes between special parts, a common FA pipe that accommodates a cable drawn from the special part into the user (customer) house, and a common FA lead-in pipe Etc. The special part is a general term for a branch part for branching / connecting for supplying to a consumer, a connecting part for connecting a cable, and the like.

  In areas where demand is low, a single pipe separate system that combines the functions of a body pipe and a common FA pipe has been introduced to reduce costs. In this one-pipe separate system, as shown in FIG. 4, a space in one pipe line 40 is divided into two using a partition 41 called a separator, and an upper space 42 called a shared FA (free access) part is formed. A lead-in wire 43 for each customer is disposed, and a sheath tube 45 accommodating a trunk cable is disposed in the lower space 44. Examples of a lead-in line to a customer include a metal cable used for a metal line service (see Non-Patent Document 2) and an optical fiber cable used for an optical fiber line service (see Non-Patent Document 3).

“Tokyo Metropolitan Electric Wire Joint Groove Maintenance Manual”, [online], Tokyo Metropolitan Construction Bureau, [searched July 8, 2015], Internet <URL: http://www.kensetsu.metro.tokyo.jp/douro/ chichuka / manyuaru-201408.pdf> "Underground outdoor line", [online], Towa Denshi Kogyo Co., Ltd. [searched July 8, 2015], Internet <URL: http://www.towa-denshi.co.jp/joho.pdf> "Optical fiber / optical fiber cable", [online], Fujikura Co., Ltd. [searched July 8, 2015], Internet <URL: http://www.fujikura.co.jp/products/tele/o_fiber_cable/ td1008.html>

  The electric wire common groove system is required to further reduce the construction cost for further promotion of non-electric poles. In the construction cost, since the article cost of the special part occupies a relatively high ratio, it is effective to reduce the number of special parts by extending the span length (installation interval) of the special part. However, the maximum span length of the special portion is limited by the layable length of the metal cable to be laid and the 2-pair underground metal outdoor line.

  On the other hand, demand for communication services is in a transitional period where metal line services with slow communication speeds and optical fiber line services with high communication speeds coexist. Metal line services are subscribed to as subscribers decrease and facilities age. Since the maintenance cost per person is increasing, the transition from metal line service to optical fiber line service is expected to progress further in the future. Therefore, there is a need for a preliminary measure for making a transition from a metal line service to an optical fiber line service quickly and at low cost.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical / metal composite lead-in wire that can reduce the construction cost in the electric wire common groove system and can also be promptly adapted to the transition from a metal line to an optical fiber line.

  The present invention has been made to solve the above-described problems, and an optical / metal composite lead-in wire according to the present invention includes a flat optical fiber cable, and at least one pair of metal cables twisted around the optical fiber cable. Are provided.

  According to the present invention, it is possible to provide an optical / metal composite lead-in wire that can reduce the construction cost in the electric wire common groove system and can also respond quickly to the transition from a metal line to an optical fiber line.

(A), (b) is sectional drawing which shows the optical and metal composite lead-in wire which concerns on one Embodiment of this invention. (A), (b) is sectional drawing which shows the optical and metal composite lead wire which concerns on other embodiment of this invention. It is the figure which showed the outline of the underground wiring in an electric wire joint groove system. It is sectional drawing of the pipe line in a 1 pipe | tube separate system.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1A, an optical / metal composite lead-in wire 1 according to an embodiment of the present invention is twisted around a flat optical fiber cable 2 and the optical fiber cable 2 as a center. Two pairs of metal cables 3. The optical fiber cable 2 and the metal cable 3 are covered from the outside by a jacket 4 for the purpose of waterproofing or the like.

  FIG. 1B shows a cross section of the optical / metal composite lead-in wire 1 cut at a position different from that in FIG. When the distance along the extending direction of the optical / metal composite lead-in wire 1 until the metal cable 3 goes around the optical fiber cable 2 in the circumferential direction is defined as the twist pitch, FIG. ) Shows a cross section at a position separated from the position by about 1/4 of the twist pitch along the extending direction.

  A known optical fiber cable 2 can be used, but it is preferable to have a steel wire or FRP as a tension member inside to increase the allowable tension.

  In the present embodiment, two pairs of metal cables 3 are twisted around the optical fiber cable 2, but the present invention is not limited to this, and one pair, or three or more pairs of metal cables 3 are used. A twisted configuration is also possible.

  In the previous embodiment, the outer cover 4 that covers the entire optical fiber cable 2 and the two pairs of metal cables 3 from the outside is provided. However, the optical / metal composite lead-in wire shown in FIGS. As shown in FIG. 10, a configuration may be provided in which a jacket 4 a that covers the optical fiber cable 2 and a jacket 4 b that covers each pair (two) of metal cables 3 are provided.

  In the optical / metal composite lead-in wires 1 and 10 of the present invention, by twisting the metal cable 3 around the optical fiber cable 2, the cable is compared with the case where it is individually accommodated in the pipeline without being twisted. The overall outer diameter can be reduced, and the accommodation efficiency in the pipe line can be increased.

  In the optical / metal composite lead-in wires 1 and 10 according to the present invention, the optical fiber cable 2 is arranged at the center, and the metal cable 3 is twisted around the optical fiber cable 2 so that the optical fiber cable 2 is connected to the entire cable. Plays the role of tension body. Here, since the allowable tension of the element portion of the optical fiber cable such as a known indoor cable or drop cable is 200 N, the allowable tension of the optical / metal composite lead-in wires 1 and 10 of this embodiment may be at least 200 N or more. Is possible.

  FIG. 3 shows an outline of the underground wiring in the electric wire joint groove system. Reference numeral 20 represents a special part, reference numeral 21 represents a rising part of the lead-in pipe, and reference numeral 22 represents a branch pipe mounting part. .

  Here, in the “Tokyo Metropolitan Electric Wire Joint Groove Maintenance Manual” described above, the span length of the common FA lead-in pipe (distance from the inner wall of the special part 20 to the center of the rising part 21 of the lead-in pipe (L1 + L2 in FIG. 3)) is the maximum The distance L1 from the branch pipe attachment part (position) 22 to the rising part 21 of the lead-in pipe is within 25m, and the distance from the inner wall of the special part 20 to the branch pipe attachment part 22 is associated with this. The condition that the distance L2 is within 35 m is defined.

  In addition to the above conditions, the layable length of a standard metal cable (200 pairs of metal cables) accommodated in a sheath pipe is defined as 70 m or less. Since the distance is set as a distance that can be constructed regardless of the cable length, the cable laying length in the sheath should be appropriately selected according to the equipment configuration of the pipeline equipment and calculate the tension. Thus, even a standard metal cable (200 pairs of metal cables) can be laid up to 200 m in calculation.

  In addition, it is difficult to change the condition that the distance L1 from the branch pipe mounting portion 22 to the rising portion 21 of the lead-in pipe is within 25 m because it is determined by the strength and the lineability of the base equipment such as the branch pipe. .

  As for the condition that the distance L2 from the inner wall of the special part 20 to the branch pipe mounting part 22 is within 35m, it is assumed that the allowable tension is 80N and a 2-pair underground outdoor line is used, and the allowable tension is exceeded during towing. Since the layable length is set so that the distance L2 is determined based on the layable length, the present invention intends to increase the span length by increasing the layable length of the lead-in wire. .

  Here, the layable length is determined by the allowable tension and the durability against the frictional force generated during towing. In the known underground outdoor line, the layable length of the 4-pair underground outdoor line is longer than that of the 2-pair underground outdoor line, and the optical fiber cable 2 is lighter than the two pairs of metal core wires. The light / metal composite lead-in wire 1 is lighter than the 4-pair underground outdoor wire. Therefore, the friction force generated during towing is larger for the 4-pair underground outdoor wire than for the light / metal composite lead-in wire 1, and the allowable tension is 4 pairs compared to 200 N for the light / metal composite lead-in wire 1. Since the underground outdoor line is 160 N, the layable length is the longest for the optical / metal composite lead-in line 1, followed by 4 pairs of underground outdoor lines and 2 pairs of underground outdoor lines.

  Below, the layable length when the optical / metal composite lead-in wire 1 having an allowable tension of 200 N is used will be described in comparison with the case of using a two-pair underground outdoor line having an allowable tension of 80 N.

When the optical / metal composite lead-in wire 1 having an allowable tension of 200 N is used, the total tension at the time of traction from the inner wall of the special part 20 to the rising part 21 of the drawing pipe is from the branch pipe mounting part 22 to the rising part 21 of the drawing pipe. And the tension T2 from the inner wall of the special part 20 to the branch pipe mounting part 22 are expressed by the following formula (1).
T1 + K × T2 <200 Formula (1)
Note that K is a rate of increase in tension, and is a value that changes according to the angle of the bent portion of the branch pipe.

Further, the tension T1 from the branch pipe mounting portion 22 to the rising portion 21 of the lead-in pipe is the distance L1 from the branch pipe mounting portion 22 to the rising portion 21 of the lead-in pipe, the friction coefficient μ, the weight W per unit length, gravity It calculates with the following formula | equation (2) using the acceleration g.
T1 = μ × W × g × L1 Formula (2)
Similarly, the tension T2 from the inner wall of the special part 20 to the branch pipe mounting part 22 is determined by the distance L2 from the inner wall of the special part 20 to the branch pipe mounting part 22, the friction coefficient μ, the weight W per unit length, and the gravitational acceleration g. It is calculated by the following formula (3) using
T2 = μ × W × g × L2 Formula (3)

On the other hand, when a two-pair underground outdoor line with an allowable tension of 80 N is used, the total tension from the inner wall of the special part 20 to the rising part 21 of the drawing pipe is from the branch pipe mounting part 22 to the rising part 21 of the drawing pipe. Using the tension T1 ′ and the tension T2 ′ from the inner wall of the special portion 20 to the branch pipe mounting portion 22, it is expressed by the following equation (4).
T1 ′ + K × T2 ′ <80 Formula (4)
Further, the tension T1 ′ and the tension T2 ′ are calculated by the following equations (5) and (6), respectively.
T1 ′ = μ × W × g × L1 ′ Formula (5)
T2 ′ = μ × W × g × L2 ′ Formula (6)

  When the weight W per unit length and the angle of the bent portion of the branch pipe are the same, and the distances L1 and L1 ′ from the branch pipe mounting portion 22 to the rising portion 21 of the lead-in pipe are the same (within 25 m), T1 = When T1 ′ and T1 = T1 ′ = 10N, in the optical / metal composite lead-in wire 1 with an allowable tension of 200N, the above equation (1) becomes 10 + K × T2 <200. On the other hand, when a two-pair underground outdoor line with an allowable tension of 80 N is used under the same conditions, the above equation (4) becomes 10 + K × T2 ′ <80. Furthermore, from the above formulas (3) and (6), using L2 and L2 ′, K × μ × W × g × L2 <190 and K × μ × W × g × L2 ′ <70, Since K × μ × W × g is common, L2 is allowed to be 190/70 times L2 ′, that is, up to about 2.7 times.

  If T1 = T1 ′ = 20N, the distance L2 can be allowed up to three times the distance L2 ′ when calculated in the same manner.

  Thus, when the optical / metal composite lead-in wire 1 having an allowable tension of 200 N is used, it is possible to attach at least twice as long as when using a two-pair underground outdoor line having an allowable tension of 80 N. .

  In addition, when using a conventional two-pair underground outdoor line with an allowable tension of 80 N, the minimum distance L3 ′ between the two special parts 20 is set such that the distance L1 ′ is an allowable maximum value of 25 m and the distance L2 ′ is 30 m. The distance L3 ′ between the two special parts 20 is 60 m, which is twice the distance L2 ′.

  On the other hand, when the optical / metal composite lead-in wire 1 having an allowable tension of 200 N according to the present invention is used, the distance L2 is more than twice the distance L2 ′, so the minimum distance L3 between the two special parts 20 is at least 120 m. That's it.

  In this way, by using the optical / metal composite lead-in wires 1 and 10 of the present invention, the allowable tension that was 80 N in the conventional 2-pair underground outdoor line can be increased to, for example, 200 N or more. The distance L2 from the inner wall 20 to the branch pipe mounting portion 22 can be elongated. As a result, it is possible to reduce the number of special parts 20 installed in the common wire groove system, and to reduce the construction cost.

  Here, in the optical / metal composite lead-in wires 1 and 10 of the present invention, the twist pitch of the metal cable 3 with respect to the optical fiber cable 2 is preferably 50 mm or less. This is because when the twist pitch exceeds 50 mm, the optical fiber cable 2 and the metal cable 3 are not integrated when the optical / metal composite lead-in wires 1 and 10 are pulled, and there is a possibility that they are displaced inside.

  In addition, when the optical / metal composite lead-in wires 1 and 10 of the present invention are used, it is not necessary to newly lay an optical fiber cable when shifting from a metal line to an optical fiber line. Therefore, it is possible to shift from a metal line to an optical fiber line quickly and at low cost.

  Furthermore, as a transitional measure in the future of all-lighting, a method of performing partial lighting can be considered. For existing metal line users, opticalization is performed to the vicinity of the user (construction of optical equipment), optical signals are converted into electrical signals using an optical / metal conversion device, and then the lead-in part uses existing metal lines The form to provide can be considered. In this case, the power supply method for the optical / metal conversion device becomes a problem, but the optical fiber cable 2 is used for communication, and power is supplied by using the metal cable 3 as a power supply line instead of a communication line from a place where a power source can be secured. Is also possible.

DESCRIPTION OF SYMBOLS 1, 10 Optical / metal composite lead-in wire 2 Optical fiber cable 3 Metal cable 4, 4a, 4b Outer sheath 20 Special part 21 Rising part of lead-in pipe 22 Branch pipe attachment part 40 Pipe line 41 Partition (separator)
42 Upper space (Common FA section)
43 Lead-in wire 44 Lower space 45 Sheath pipe

Claims (4)

A flat fiber optic cable;
An optical / metal composite lead-in wire comprising: at least one pair of metal cables twisted around the optical fiber cable.   The optical / metal composite lead-in wire according to claim 1, wherein a twist pitch of the metal cable is 50 mm or less.   3. The optical / metal composite lead-in wire according to claim 1, wherein the optical fiber cable has a tension member made of steel wire or FRP inside.   The optical / metal composite lead-in wire according to any one of claims 1 to 3, wherein the optical fiber cable has an allowable tension of 200 N or more.

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