JPH0526649Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to an overhead ground wire incorporating optical fibers. Fiber optic cables can transmit large amounts of information;
Furthermore, due to its low loss, non-inductive, and insulating properties, optical fibers are incorporated into overhead ground wires to transmit information between substations, transmit information on power transmission lines, and countermeasures against television disturbances. It is considered to be used for this purpose. Optical fibers to be incorporated into the above-mentioned overhead ground wire include:
For example, it is constructed by finishing six optical fiber cores in a circular shape around the tension member and applying a silicone resin sheath, and is drawn into a narrow diameter aluminum tube with a margin that allows it to be replaced. It is something that exists. A typical structural example of a composite overhead ground wire composed of such an aluminum tube containing optical fiber and an overhead ground wire is shown in FIG. That is, an aluminum pipe 2 with a built-in optical fiber 1 is placed inside, and around it is a galvanized steel wire or an aluminum-coated steel wire 3 (circular wire) with a circular cross section and a diameter slightly smaller than the diameter of the aluminum pipe 2. Aluminum wires 4 (segment wires) with a similar cross-sectional rectangular shape and having a thickness equal to this diameter are alternately combined so that the segment wires are interlocked with the circular wires to form a multilayer (two layers in the figure). This is a composite overhead ground wire twisted in a circular manner to create a bridge structure. In the structure of such a composite overhead ground wire, the aluminum pipe containing the optical fiber is protected by a bridge structure of circular wires and segment wires, so even if an external force is applied to the wire, the central aluminum pipe will not be damaged. It is safe as there is no risk of crushing or deforming, but above all, since segmented wires with a special shape are used, manufacturing the wire itself is time-consuming and costly, and it is difficult to twist. Since the linear velocity also decreases, the cost inevitably increases. The composite overhead ground wire of the present invention consists of high tensile strength wires such as galvanized steel wires and aluminum coated steel wires that constitute the overhead ground wire itself, and a combination of these high tensile strength wires and aluminum wires such as aluminum alloy wires. By making each wire used in a normal overhead ground wire into a wire with a circular cross section, the composite overhead ground wire is free from the above-mentioned drawbacks in wire manufacturing or stranding technology. In particular, the metal tube housing the optical fiber is made of an aluminum-magnesium alloy, and its thickness is determined in relation to the limit load of the metal tube. An example of the composite overhead ground wire of the present invention will be described with reference to the drawings. As shown in FIG. Or, it is made by twisting aluminum coated wires 3 (both are circular wires), and the material of the aluminum pipe is particularly aluminum-magnesium alloy, and its size is almost the same as the above-mentioned galvanized steel wire or aluminum coated steel wire. This is the diameter. In the optical fiber composite overhead ground wire of the present invention, compared to the conventional example shown in Figure 1, there is a risk of crushing or deformation of the aluminum/magnesium alloy pipe during overhead line construction, so this problem was solved. This is the invention. The outline of this invention is as shown in Fig. 3, where the wall thickness of the pipe is tmm, the radius to the center line of the aluminum pipe is Rmm, and the limit load of the aluminum pipe is Ykg. This is a composite overhead ground wire characterized in that the alloy pipe satisfies the general formula t/R≧og ₁₀ Y-1.85/1.6, and Y is selected in the range of 100 to 500 kg, and t/R is selected in the range of 0.09 to 0.53. . That is, the present inventors fabricated various aluminum-magnesium alloy pipes to incorporate optical fibers as shown in FIG. 3, and set the pipe wall thickness to t and the radius to the center line of the pipe wall thickness to be After doing various research on the limit load of the product under such conditions, we were able to obtain the results shown in Figure 4. Figure 4 shows an aluminum-magnesium alloy pipe that is actually used, cut to a length of 3 cm, placed on a horizontally fixed table, and a weight (load) applied to the pipe to crush it. The results of examining the deformation are determined by the ratio t/R of wall thickness t and radius R and the limit load Y.
This is a graph of the relationship between t/R=og ₁₀ Y-1.85/1.6.
It shows t/R of magnesium alloy pipe. Therefore, it can be seen that an aluminum-magnesium alloy pipe capable of withstanding external loads must satisfy t/R≧og ₁₀ Y-1.85/1.6. The critical load here refers to the limit at which the pipe hardly deforms in the crushing deformation test mentioned above, and is usually the same as the outer diameter deformation rate of the original circular pipe.
Up to 0.2%. Aluminum-magnesium alloy pipes will undergo rapid deformation if a load that exceeds this limit is applied. By the way, in actual overhead line construction, the external load applied varies greatly depending on the construction method. For example, when replacing a conventional composite overhead ground wire, it is recommended to extend the line with a tension of 200 to 300 kg. However, when constructing a new overhead wire, the tension can reach up to 1000 kg, depending on the wire size. Therefore, in order to confirm the relationship between the graph in Fig. 4 and the overhead wire tension, we created an overhead ground wire model as shown in Fig. 2 using various aluminum pipes with different t/R, and as shown in Fig. 5. The results of experiments conducted using the simulated test equipment shown are as follows. In the test apparatus shown in FIG. 5, both ends of a sample (test wire) 5 are connected to a steel wire 6, steady rests 7, 7 are attached to the connected ends, and the sample 5 is attached to a metal wheel 8 at the top. The wires are looped around the lower pulleys 9, 9, respectively. Note that the bending angle (outer angle) of the metal wheel 8 of the sample is 60°. 10 is a tension meter. Further, in the horizontal part of the steel wire 6, another steel wire 6-b
is pulled by an upper winch 11, the bottom part is fixed at one location 12 on the bottom of the steel wire 6, and is hung around pulleys 13, 13 provided at two locations to form a loop-shaped traction wire. Therefore, by moving the traction wire left and right, the test wire 5 is also reciprocated around the metal wheel 8, and a predetermined tension is applied, and after such a test, the collapsed state of the pipe on the test wire 5 is examined. This is what I did. The test results using this device are shown in Table 1 and Figure 4. For example, when the tension is 300Kg, it corresponds to a limit load of 100Kg, when the tension is 1000Kg, it corresponds to a limit load of 330Kg, and when the tension is 1500Kg, it corresponds to a limit load of 330Kg. It was found that when the tension is 1700Kg, it corresponds to a limit load of 450Kg, and when the tension is 1700Kg, it corresponds to a limit load of 500Kg. In particular, it has been found that it is sufficiently practical if the critical load required from the overhead wire tension is between 100Kg and 500Kg. Therefore, in this case, t/R is 0.09 or more for the former and 0.09 or more for the latter.
It can be seen that if it is 0.53 or more, it can withstand practical use without being crushed. Actual overhead wire tension is 1700Kg
Since it almost never exceeds t/R, the upper limit of t/R is
There is no problem as 0.53.

[Table] It was found that the practical thickness of the aluminum/magnesium alloy pipe is approximately R = 2.0 to 5.0 mm based on the current construction design, the strength of the metal wheel, etc. The composite overhead ground wire of this invention can reduce costs because all the wires around the aluminum/magnesium alloy pipe are made of circular wires, and the aluminum/magnesium alloy pipe can be adjusted to t/R according to the limit load. Since it is designed to handle external loads, there is no risk of crushing it.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing an example of the structure of a conventional optical fiber composite overhead ground wire, Figure 2 is a cross-sectional view of the optical fiber composite overhead ground wire of the present invention, and Figure 3 is the aluminum used in the present invention.・Magnesium alloy pipe 2
Figure 4 shows the limit load and t/t of the aluminum-magnesium alloy pipe used in this invention.
A graph showing the relationship between R and FIG. 5 is a front view of the simulation test device. 1... Optical fiber, 2... Aluminum magnesium alloy pipe, 3... Circular wire, 4... Segment wire, 5... Sample (test wire), 6... Steel wire,
6-b... Steel wire, 7... Steady rest, 8... Gold wheel,
9... Pulley, 10... Tension meter, 11... Winch, 12... Fixed, 13... Pulley.

Claims (1)

[Scope of Claim for Utility Model Registration] Around an aluminum/magnesium alloy pipe containing an optical fiber, galvanized steel wire or aluminum-coated steel wire with a circular cross section and approximately the same diameter as the pipe constituting the overhead ground wire is twisted. In the composite overhead ground wire, the aluminum-magnesium alloy pipe has a wall thickness of t.
mm, radius to center line of wall thickness is Rmm, limit load is YKg, Y is 100 to 500Kg, t/R is
An optical fiber composite overhead ground wire characterized in that an aluminum-magnesium alloy pipe is applied which is determined to satisfy the following formula t/R≧og ₁₀ Y-1.85/1.6 in the range of 0.09 to 0.53.