JPH07122116A - Lightning resistant type optical fiber composite overhead earth-wire - Google Patents

Abstract

PURPOSE:To simultaneously satisfy both the improvement if lighting resistant performance and the prevention of thermal damage of optical fiber. CONSTITUTION:An optical fiber composite overhead earth-wire is constituted in such a manner that an optical fiber unit 4 housing optical fiber 3 in a pipe 2 is incorporated therein, and a plurality of deformed cross-sectional element wires 5, wherein circumferences of steel cores 5a are covered with aluminum coating layers 5b, are twisted around the optical fiber unit 4. In the deformed cross-sectional element wire 5, an aluminum projection 6 is imparted to an outer side surface of the aluminum coating layer 5b. A cross-sectional area ratio A/B of a cross-sectional area A of a steel core 5a part to a cross-sectional area B of the deformed cross-sectional element wire 5 is 80% or larger. When the cross-sectional area ratio A/B is 80%, conductivity of the deformed cross-sectional element wire 5 is 18%. A cross-sectional area C of the aluminum projection 6 is determined so that the conductivity of the deformed cross-sectional element wire 5 may be, for example, 20 %. Since the cross-sectional area ratio of the steel core 5a excellent in heat resistance is large, lighting resistance performance is improved. On the other hand, since the aluminum projection 6 compensates the decrease of the conductivity, thermal damage of the optical fiber 3 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning-proof optical fiber composite overhead ground wire.

[0002]

2. Description of the Related Art An aluminum-covered steel wire for an overhead ground wire in which a steel core is covered with an aluminum coating layer has a large cross-sectional area ratio of the steel core portion having a high melting point, so that it does not easily melt during a lightning strike The performance is good. However, when the outer diameter of the overhead ground wire is constant, the conductivity decreases when the cross-sectional area ratio of the steel core is large, and a large amount of heat is generated when an induced current or a lightning current from the mains of the transmission line flows. In particular, in the case of an optical fiber composite overhead ground wire, the temperature of the built-in optical fiber unit rises significantly and the optical fiber may be thermally damaged.
Therefore, in the optical fiber composite overhead ground wire, an aluminum covered steel wire having a conductivity of at least 20% or more is used. The fact that the electrical conductivity of the aluminum-covered steel wire is 20% or more corresponds to that the ratio of the sectional area of the steel core portion to the sectional area of the entire aluminum-covered steel wire is 75% or less.

[0003]

The above-mentioned conventional conductivity is 2
The aluminum-clad steel wire of 0% or more does not generate a large amount of heat when an induced current or a lightning current flows from the main line of the power transmission line, so it is possible to prevent the thermal damage to the optical fiber. Since the cross-sectional area ratio of the cross-sectional area of the steel core to the cross-sectional area of the entire aluminum-covered steel wire is as small as 75% or less, there is not much room for the mechanical tensile strength of the wire, and the arc during lightning strikes The wire was easy to melt and the lightning resistance was poor.

The present invention has been made in view of the above circumstances, and is a novel optical fiber composite overhead ground wire capable of satisfying both good lightning resistance and thermal damage to the built-in optical fiber. The purpose is to provide.

[0005]

According to a first aspect of the invention for solving the above-mentioned problems, an outermost layer is formed by a plurality of modified cross-section strands having a built-in optical fiber unit and a steel core surrounded by an aluminum coating layer. A lightning-proof optical fiber composite overhead ground wire formed by twisting wires, wherein at least a part of the deformed cross-section strands of the plurality of deformed cross-section strands is formed on the outer surface of the aluminum coating layer by aluminum. With the addition of ridges,
The cross-sectional area of the steel core portion is A, and the cross-sectional area of the modified cross-section wire is B
Then, A / B ≧ 0.8.

According to the second aspect of the present invention, there is provided a lightning-proof type light emitting device in which an outermost stranded wire is formed by a plurality of round-shaped strands each having a built-in optical fiber unit and a steel core surrounded by an aluminum coating layer. In the case of an optical fiber composite overhead ground wire, where A is the cross-sectional area of the steel core portion and B is the cross-sectional area of the round cross-section element wire, A / B ≧ 0.8 and It is characterized in that an aluminum rod is spirally wound around the outer periphery of the outermost stranded wire made of a shaped cross-section wire.

According to the invention of claim 3, in the optical fiber composite overhead ground wire of claim 1, when the cross-sectional area of the aluminum projection is C, ΣA / ( The sectional area C of the aluminum ridges is set so that ΣB + ΣC) ≦ 0.75. Where ΣA is the sum of the cross-sectional areas of the steel core in the entire overhead ground wire section excluding the optical fiber unit, and ΣB is the sum of the cross-sectional areas of the modified cross-section wires in the entire overhead ground wire section excluding the optical fiber unit. Sum of cross-sectional areas of aluminum ridges in the entire overhead ground wire section excluding the optical fiber unit

According to a fourth aspect of the present invention, in the optical fiber composite overhead ground wire of the second aspect, when the sectional area of the aluminum rod is C, ΣA / (ΣB + ΣC) for the entire overhead ground wire portion excluding the optical fiber unit portion. ) ≦ 0.75, the cross-sectional area C of the aluminum rod is set. Where ΣA is the sum of the cross-sectional areas of the steel core in the entire overhead ground wire section excluding the optical fiber unit, and ΣB is the sum of the cross-sectional areas of the round cross-section element wires in the entire overhead ground wire section excluding the optical fiber unit ΣC. Is the sum of the cross-sectional areas of the aluminum rod in the entire overhead ground wire section excluding the optical fiber unit.

[0009]

In the above structure, since the steel core has a large cross-sectional area ratio, the mechanical tensile strength of the wire is high, and the lightning resistance is good because it is less likely to melt due to an arc during a lightning stroke. Then, with respect to the decrease in conductivity due to the large cross-sectional area ratio of the steel core portion, the aluminum ridges or aluminum rods make up for the shortage and secure the necessary conductivity.

Further, since the aluminum ridges and the aluminum rods are used as a melting loss margin, the outermost layer stranded wire is less damaged.

[0011]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a cross section of the optical fiber composite overhead ground wire of claim 1. This optical fiber composite overhead ground wire 1 is an aluminum-covered steel wire in which the circumference of a steel core 5a is covered with an aluminum coating layer 5b on the outer circumference of an optical fiber unit 4 in which an optical fiber 3 is housed in a pipe 2 of aluminum or the like. This is a structure in which a plurality of modified cross-section strands 5 are twisted together. Each modified cross-section strand 5 has an aluminum ridge 7 added to the outer surface of the aluminum coating layer 5b. When the cross-sectional area of the steel core 5a portion is A and the cross-sectional area of the modified cross-section element wire 5 including the steel core 5a not including the aluminum ridges 6 and the aluminum coating layer 5b is B, /B≧0.8. That is, the cross-sectional area ratio A / B of the cross-sectional area A of the steel core 5a portion to the cross-sectional area B of the deformed cross-section strand 5 is 80%.
That is all. When the cross-sectional area ratio is 80%, the conductivity of the deformed cross-section element wire 5 is 18%. The aluminum ridge 6 is formed integrally with the aluminum coating layer 5b.
The cross-sectional area C of the aluminum ridge 6 has a cross-sectional area ratio A / (B + C) of 75 to the total cross-sectional area (B + C) of the deformed cross-section wire 5 of the cross-sectional area A of the steel core 5a and the aluminum ridge 6. It is set to be less than or equal to%. That is, in the embodiment,
All-shaped cross-section wire 5 of the same shape with aluminum ridges 6 added
Since, is used, ΣA / (ΣB + ΣC) ≦ 0.75. In addition, the cross-sectional area ratio of 75% or less means that the portion of the optical fiber composite overhead ground wire 1 excluding the optical fiber unit 4, that is, the entire overhead ground wire portion including the deformed cross-section wire 5 and the aluminum ridge 6 is electrically conductive. This corresponds to a rate of 20% or more. In the illustrated example, the aluminum ridges 6 are added to all the modified cross-section strands 5, but the aluminum ridges 6 may be added only to some of the modified cross-section strands 5.

FIG. 2 shows an embodiment of the optical fiber composite overhead ground wire of claim 2. This optical fiber composite overhead ground wire 11
Is a structure in which a plurality of round cross-section wires 15 are twisted around the outer circumference of an optical fiber unit 4 similar to the above, and an aluminum rod 16 is spirally wound around the outer circumference of this twisted wire as shown in FIG. Is. Reference numeral 15a is a round cross-section wire 15
The steel core portion, reference numeral 15b, indicates an aluminum coating layer. The round cross-section wire 15 has a cross-sectional area of the steel core 15a portion of A,
When the cross-sectional area of the circular cross-section strand 15 is B, A / B ≧ 0.8. That is, the cross-sectional area ratio A / B of the cross-sectional area A of the steel core 15a portion to the cross-sectional area B of the round cross-section strand 15 is 8
It is set to 0% or more. When the cross-sectional area ratio is 80%, the conductivity of the round cross-section strand 15 is 18%. Also,
The cross-sectional area C of the aluminum rod 16 has a cross-sectional area ratio A / (B + C) of 75% or less with respect to the cross-sectional area (B + C) of the round cross-section wire 15 and the aluminum rod 16 of the cross-sectional area A of the steel core 15a. Is set to. That is, in the embodiment, since one aluminum rod 16 is provided, ΣA / (ΣB + C) ≦ 0.75. Note that the cross-sectional area ratio of 75% means the electrical conductivity of the portion of the optical fiber composite overhead ground wire 11 excluding the optical fiber unit 4, that is, the entire overhead ground wire portion including the round cross-section wire 15 and the aluminum rod 16. Corresponds to 20% or more. The winding direction of the aluminum rod 16 is opposite to the winding direction of the round cross-section wire 15 as shown in FIG. 3 in order to prevent the aluminum rod 16 from falling into the twist groove of the twisted wire consisting of the round cross-section wire 15. It is better to Moreover, the number of the aluminum rods 16 is not limited to one, and may be two or more. Further, the round cross-section wire 15 may be a modified cross-section wire as shown in FIG.

The above-mentioned optical fiber composite overhead ground wire 1 or 1
1, the cross-sectional area A of the steel core 5a portion or 15a portion
Since the cross-sectional area ratio A / B of the odd-shaped cross-section wire 5 or the round-shaped cross-section wire 15 is large relative to the cross-section area B, the wires 5 and 15 have an increased mechanical tensile strength, and are melted by the arc during lightning strike. If it becomes difficult, the lightning resistance is improved. Further, with respect to the decrease in conductivity due to the large cross-sectional area ratio A / B of the steel core 5a or 15a portion, the aluminum ridge 6 or the aluminum rod 16 compensates for the shortage, and the induced current from the transmission line main line or The electrical conductivity of 20% required to prevent thermal damage to the optical fiber 3 when a lightning current flows is ensured.

Further, since the aluminum ridges 6 or the aluminum rods 16 serve as a melting loss at the time of a lightning stroke, the deformed section wire 5 or the round section wire 15 is less damaged. The damage received can be reduced as much as possible.

The cross-sectional area ratio A / B of the steel core 5a or 15a with respect to the deformed section wire 5 or the round section wire 15
May be 80% or more as described above. For example, when it is 87%, it is used as an overhead ground wire which is a twisted body of a plurality of irregularly shaped cross-section wires 5 or round cross-section wires 15. The conductivity is 14%, and the conductivity is 6% short of the conductivity of 20% required to prevent the thermal damage of the optical fiber 3 when the induced current or the lightning current from the mains of the transmission line flows. However, this shortage is compensated by the cross-sectional area C of the aluminum ridge 6 or the aluminum rod 16.

Optical fiber composite overhead ground wires 1 and 11 of the embodiment
Is a structure having a single twisted wire on the outer periphery of the optical fiber unit 4, but is naturally applicable to a structure having a plurality of twisted wires. When the stranded wire has a plurality of layers, at least the outermost stranded wire has the above-mentioned configuration.

[0017]

EFFECTS OF THE INVENTION According to the present invention, in a wire having a modified or round cross section in which the circumference of the steel core is covered with an aluminum coating layer, the cross-sectional area ratio of the steel core is increased. The mechanical tensile strength was improved, and it became difficult to melt due to arc during lightning stroke, and the lightning resistance characteristics were improved. For the decrease in conductivity due to the large cross-sectional area ratio of the steel core part, an aluminum ridge or aluminum rod is used to compensate for the shortage, and when an induced current or a lightning current from the mains of the transmission line flows. The electrical conductivity necessary to prevent thermal damage to the optical fiber can be secured. In this way, it is possible to satisfy both the improvement of lightning resistance and the prevention of damage to the optical fiber at the same time.

Further, since the aluminum ridges and the aluminum rods serve as a melting loss margin, it is possible to suppress damage to the twisted wire itself due to a lightning stroke as much as possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a lightning-proof optical fiber composite overhead ground wire according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a lightning-proof optical fiber composite overhead ground wire according to another embodiment of the present invention.

FIG. 3 is a side view of the lightning-proof optical fiber composite overhead ground wire of FIG.

[Explanation of symbols]

 1,11 Optical fiber composite overhead ground wire 2 Pipe 3 Optical fiber 4 Optical fiber unit 5 Deformed cross-section wire 5a Steel core 5b Aluminum coating layer 6 Aluminum ridge 15 Round cross-section wire 15a Steel core 15b Aluminum coating layer 16 Aluminum rod

Claims (4)

[Claims] 1. An outermost stranded wire is formed by a plurality of deformed cross-section strands (5) containing an optical fiber unit (4) and surrounding a steel core (5a) with an aluminum coating layer (5b). Which is a lightning-proof optical fiber composite overhead ground wire, wherein at least some of the deformed cross-section strands (5) have an aluminum coating layer (5b).
Aluminum ridge (6) is added to the outer surface of
When the cross-sectional area of the steel core (5a) is A and the cross-sectional area of the deformed cross-section strand (5) is B, A / B ≧ 0.8, which is a lightning-proof optical fiber composite aerial structure. Ground line. 2. An aluminum coating layer (15b) surrounding the steel core (15a) while incorporating the optical fiber unit (4).
A lightning-proof type optical fiber composite overhead ground wire in which the outermost stranded wire is formed by a plurality of round-shaped strands (15) covered with a steel core (15a) having a cross-sectional area of A , Where A / B ≧ 0.8 when the cross-sectional area of the round cross-section wire (15) is B, and the outer circumference of the outermost stranded wire composed of the plurality of round cross-section wires (15) A lightning-proof optical fiber composite overhead ground wire comprising an aluminum rod (16) wound in a spiral shape. 3. When the cross-sectional area of the aluminum ridge (6) is C, ΣA / (ΣB + ΣC) ≦ 0.75 for the entire overhead ground wire portion excluding the optical fiber unit (4) portion. The lightning protection type optical fiber composite overhead ground wire according to claim 1, wherein the cross-sectional area C of the aluminum ridge (6) is set. Where ΣA is the sum of the cross-sectional areas of the steel core (5a) part in the entire overhead ground wire part excluding the optical fiber unit (4) ΣB is an irregular cross section of the entire overhead ground wire part excluding the optical fiber unit (4) ΣC is the sum of the cross-sectional areas of the aluminum ridges (6) in the entire overhead ground wire except the optical fiber unit (4). 4. The cross-sectional area of the aluminum rod (16) is C
Then, the cross-sectional area C of the aluminum rod (16) is set so that ΣA / (ΣB + ΣC) ≦ 0.75 with respect to the entire overhead ground wire portion excluding the optical fiber unit (4) portion. 2. The lightning-proof type optical fiber composite overhead ground wire described in 2. Where ΣA is the sum of the cross-sectional areas of the steel core (15a) part in the entire overhead ground wire part excluding the optical fiber unit (4) ΣB is a round shape for the entire overhead ground wire part excluding the optical fiber unit (4) The sum ΣC of the cross-section areas of the cross-section strands (15) is the sum of the cross-section areas of the aluminum rod (16) in the entire overhead ground wire section excluding the optical fiber unit (4).