JPH0727528Y2 - Optical composite overhead ground wire - Google Patents

Description

[Technical Field] The present invention relates to an optical composite overhead ground wire which is used in an overhead power transmission line and has an optical transmission line built therein.

[Prior art and its problems] As an optical composite overhead ground wire, conventionally, an optical transmission line is housed in the groove of a metal spacer having a spiral groove in the longitudinal direction, a metal pipe is covered on the outer periphery thereof, and a large number of them are further arranged on the outer periphery thereof. It is known that the outer layer strands of (1) are twisted together. In this type of optical composite overhead ground wire, aluminum-coated steel wire or aluminum alloy wire with high strength, high heat resistance, and to some extent conductivity is used for the outer layer wire, In order to increase the current capacity of the overhead ground wire by allowing sufficient current sharing, the metal pipe was made of conductive aluminum with a conductivity of 61% or more.

By the way, there are two types of optical composite overhead ground wire, one with a single outer layer and the other with a double strand.However, in the former overhead ground wire, when a large current instantaneously flows due to a lightning strike, etc. ,
It has been found that the temperature of the metal pipe becomes too high and the sheath of the optical transmission line may deteriorate, or the loss or breakage of the optical fiber inside may occur.

For example, the metal spacer is made of aluminum alloy with a cross-sectional area of 5.1 mm ² and a conductivity of 52%, the metal pipe is made of aluminum with an outer diameter of 5.2 mm, an inner diameter of 4.2 mm, and a conductivity of 61%, and 3.2 mm as an outer layer wire on top of it. In the overhead ground wire made by twisting 8 aluminum-coated steel wires,
When the current is applied for 0.75 seconds, the temperature of the outer layer wire is about 30
Although it was 0 ° C, it became clear that the temperature of the metal pipe part reached 400 ° C.

This is because the current flowing through the metal pipe becomes relatively large in the optical composite overhead ground wire in which the outer layer element wire has a single strand.

[Means for solving problems and their effects]

In order to solve the above-mentioned problems of the prior art, the present invention accommodates an optical transmission line in the groove of a metal spacer having a spiral groove in the longitudinal direction, and covers a metal pipe on the outer periphery thereof.
Furthermore, in the optical composite overhead ground wire formed by twisting one outer layer wire around the outer circumference, the metal pipe is formed of a material having a conductivity of 45% or less.

The reason why the conductivity of the metal pipe is lowered in this way is that the shunt of the current to the metal pipe is reduced and the temperature rise of the metal pipe is suppressed to a low level.

〔Example〕

FIG. 1 shows an optical composite overhead ground wire according to an embodiment of the present invention. In the figure, 1 is a metal spacer having a spiral groove 2 in the longitudinal direction, 3 is an optical transmission line housed in the spiral groove 2, 4 is a metal pipe coated on the outer periphery of the metal spacer 1, and 5 is an outer periphery thereof. It is a single strand of outer layer wire. In this optical composite overhead ground wire, the metal spacer 1, the optical transmission line 3 and the outer layer element wire 5 have the same structure as the conventional one, but the metal pipe 4 is made of a material having a conductivity of 45% or less. is there.

For example, the metal spacer 1 is made of an aluminum alloy having a cross-sectional area of 5.1 mm ² and a conductivity of 52%, the metal pipe 4 is an outer diameter of 5.2 mm, an inner diameter of 4.2 mm,
An overhead ground wire made of aluminum alloy with a conductivity of 45%, on which 8 3.2mm aluminum-coated steel wires were twisted as the outer layer wire 5, and when a current of 9KA was applied for 0.75 seconds, the outer layer wire portion The maximum temperature of the metal pipe was about 300 ℃. As a result, the optical transmission line 3 was not damaged by heat.

In the above embodiment, an aluminum alloy having a conductivity of 52% was used for the metal spacer, but if the material is also a material having a conductivity of 45% or less, the ambient temperature of the optical transmission line can be further lowered.

[Effect of device]

As described above, according to the present invention, a metal pipe in an optical composite overhead ground wire in which the outer layer wire is a single strand is used,
Since it is made of a material as low as 10% or less, the current shunted to the metal pipe becomes small, and the temperature rise of the metal pipe can be suppressed to a low level. Therefore, it is possible to prevent the optical transmission line in the metal pipe from being damaged by heat.

[Brief description of drawings]

FIG. 1 is a sectional view showing an optical composite overhead ground wire according to an embodiment of the present invention. 1-metal spacer, 2-helical groove, 3-optical transmission line, 4-
Metal pipe, 5 to outer layer wire.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References 60-118818 (JP, U) actual 58-134815 (JP, U) actual 57-161710 (JP, U) actual 60- 164715 (JP, U)

Claims (2)

[Scope of utility model registration request] 1. An optical composite aerial structure in which an optical transmission line is housed in the groove of a metal spacer having a spiral groove in the longitudinal direction, a metal pipe is covered on the outer circumference thereof, and an outer layer element wire is further twisted on the outer circumference thereof. At the ground wire, the above metal pipe has a conductivity of 45%.
An optical composite overhead ground wire characterized by being formed of the following materials. 2. The optical composite overhead ground wire according to claim 1 of the utility model registration claim, wherein the metal spacer is also made of a material having a conductivity of 45% or less.