JPH05333216A - Method for stringing optical fiber composite overhead earth wire - Google Patents

Abstract

PURPOSE:To secure a sound overhead state at all times without any remaining or concentration of stress in an internal optical fiber by allowing the optical fiber to urge sliding after its stringing. CONSTITUTION:After the optical fiber composite overhead earth wire 1 is strung, the overhead earth wire 1 is drawn in a straight line shape without fixing its end part by a gripping member, etc. Thus, the earth wire is drawn in the straight line state while maintaining the end part free as it is and then optical fiber 1a releases its residual tensile stress and shrinks by (1) from the end part of the pipe 1b by sliding on the internal surface of a pipe 1b, so that the stress is released. After the stress is thus released, the wire may be looped and connected to a connection box while maintaining it to the straight line state as it is, but when the wire is connected to the connection box, the wire 1 is preferably wound and bundle in the vicinity of its end part. Consequently, the frictional force is generated inside the bundle winding owing to the movement of the optical fiber and the stress is therefore dispersed, so that the stress is prevented from being accumulated at a specific position at the end part of the optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a method of installing an optical fiber composite overhead ground wire in which an optical fiber is housed inside so that the overhead ground wire also serves as a communication line.

[0002]

2. Description of the Related Art Utilizing the property that an optical fiber is not affected by electromagnetic waves, the optical fiber can be housed in an electric wire or cable, and a communication line can be constructed using the electric wire or cable as a carrier. Widely realized.
An overhead ground wire that is installed on an overhead power transmission line is suitable for use as the carrier because it has a moderate diameter and is not a conductive member that carries high-voltage current. Optical fiber composite aerial ground wire, which is a composite of fibers, has been put to practical use since early on.

The structure has a cross-sectional structure as shown in FIG. 2, for example, in which a pipe 1b is arranged in the center and strands 1c and 1c are twisted around the outer periphery to form an overhead ground wire, The optical fiber itself is slidably accommodated in the hollow of the pipe 1b, which is a chamber for accommodating the optical fiber 1a, to constitute the optical fiber composite overhead ground wire 1. Such an optical fiber composite overhead ground wire 1 is drawn by an ordinary hanging wire construction method or a tension drawing construction method, and after holding the ground wire itself to a steel tower, the excess length is further reduced and the optical fiber in the connection box is reduced. An overhead line is made depending on the connection method. The connection box 3 is fixed to, for example, an angle 5 of a steel tower as shown in FIG. 1, and the optical fiber composite overhead ground wire 1 that has been pulled down is brought to the connection box 3 in a loop shape and fixed to the fixing portion 4. The optical fiber 1a that is fixed and stripped and exposed is separately connected inside the connection box 3.

The optical fiber composite overhead ground wire 1 thus constructed by the overhead wire receives a large overhead wire tension during the overhead wire, and the tension remains in the internal optical fiber 1a as tensile stress. Furthermore, even when connected to the junction box 3 in a looped state, stress is generated due to expansion and contraction due to temperature difference of electric wires, etc., and the stress is superposed on the residual stress, and in particular, the fixing portion to the junction box 3 is fixed. A stress concentration portion is formed in the vicinity of 4. The occurrence of residual stress or concentration of stress on an optical fiber is by no means desirable for optical fibers whose mechanical strength is significantly different from that of other wire constituent materials. This can cause damage to the fiber.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide an overhead line method for an optical fiber composite overhead ground wire which can always maintain a healthy overhead wire state without causing residual stress or concentration of stress in the internal optical fiber 1a.

[0006]

SUMMARY OF THE INVENTION That is, according to the present invention, after an optical fiber composite overhead ground wire is installed, the optical fiber is urged to slide so that the stress applied during the installation work is released. The feature is that the wire is installed in a state where no abnormal stress is applied to the optical fiber, thereby eliminating the risk of damage to the optical fiber.

[0007]

EXAMPLES Examples will be described below.

FIG. 3 is an explanatory view showing a state in which the optical fiber composite overhead ground wire 1 is installed by the hanging method.
Is a drum, 11 and 11 are hanging wheels, 12 is a main rope, 13 is a winch, and A, B, C and D are steel towers. The hanging wire construction method uses the hanging wire car 1 on the main rope 12 stretched over the steel towers A to D.
1 and 11 are developed as shown in the figure, and the overhead ground wire 1 is extended on the lower sheave of the hanging wheel 11. During the extension, it is possible to extend the wire with extremely low tension. . Then, when the overhead ground wire 1 is extended as shown in FIG. 3, the overhead ground wire 1 and the main rope 12 are inverted as shown in FIG. 4, and the ground wire 1 is used as a guide line and the main rope 12 is hung. Gold cars 11, 11 are collected,
The overhead ground wire 1 extended as shown in FIG. 5 is left in the steel tower in an overhead wire state. The overhead ground wire 1 is tightly tensioned, a predetermined drawing and connection process is performed, and the overhead wire is completed.

FIG. 8 shows the tension applied to the electric wire during the above-mentioned overhead wire work and the behavior of elongation at that time, where ○ is the behavior in the hanging wire construction method, and Δ is the normal tension wire extension. And shows the state under the overhead wire tension after the final overhead wire regardless of which method is used. In the case of the hanging metal construction method, the wire drawing tension is small, and only the wire drawing tension shown in FIG. 8a is applied during wire drawing. The elongation under such a tension has a greater factor of elongation due to untwisting or tightening of the twisted wire, rather than elongation of the material itself. What is indicated by ε in FIG. 8 is the initial elongation. When the extension of the overhead ground wire 1 is completed and the main rope 12 is reversed as shown in FIG.
The load of No. 1 is directly applied, and the overhead ground wire 1 must be pulled up so that the sag does not increase in such a state, and the load is increased, and the tension and extension of FIG. 8b occur. Once the gold wheels 11 and 11 have been collected, the load applied by them disappears, and the final overhead wire load c becomes and the elongation also becomes a value commensurate with the load c. on the other hand,
In the case of the tension wire drawing, the wire drawing tension is large and d is shown in FIG. 8 during the wire drawing.
The wire is tensioned by the wire tension, finally tightly tensioned, and then the overhead wire tension c is applied.

In the overhead wire of the overhead ground wire, the above-described tension fluctuation and elongation fluctuation occur, but the above-mentioned tension and the above-mentioned tension are caused because the optical fiber composite overhead ground wire 1 has the structure shown in FIG. The extension is also transmitted to the internal optical fiber 1a. This tension remains as a residual stress after the completion of the overhead wire, and a load is superposed when a change in the temperature of the electric wire or a change in the elongation due to a wind pressure load occurs. However, there is a risk that the optical fiber may be damaged and the optical fiber may be damaged.

According to the present invention, after the wire is suspended, the end portion of the optical fiber is set in a free state, and the tension held by the optical fiber itself is used to cause sliding in the housing pipe to reduce its length. By doing so, the stress applied to the optical fiber during the overhead wire work is released. FIG. 6 shows such a state, and the end portion of the overhead ground wire 1 is linearly extended without being fixed by a gripping member or the like. In this way, if the fiber is stretched linearly with the end free, the optical fiber 1a releases its own tensile residual stress to release the residual tensile stress of the pipe 1b, as shown in the enlarged cross-sectional view of the portion P in FIG. The inner surface slides and contracts, and is retracted from the end of the pipe 1b by 1 to release the stress. When the stress is released in this way, the connection box 3 may be looped and connected in the straight line state, but when connecting to the connection box 3, a portion near the end of the overhead ground wire 1 as shown in FIG. It is preferable to form a large bundle winding 2. By performing the bundle winding, a frictional force is generated inside the bundle winding with respect to the movement of the optical fiber 1a, whereby the stress is dispersed, and the stress is concentrated on a specific position at the end of the optical fiber 1a. It is prevented from accumulating. The above shows an example in which the bundle winding 2 is formed after releasing the stress of the optical fiber. First, the bundle winding 2 is formed, and then the optical fiber 1a is inserted from the end of the wire into the pipe 1b. The stress may be released by a method of sliding the optical fiber by pushing it artificially. Furthermore, although an example of bundling is shown above, if the stress release is sufficiently executed, a method of adhesively fixing the optical fiber at the end to the pipe may be used instead of such bundling. Therefore, the optical fiber inside the wire is kept in a stress-released state.

[0012]

As described above, according to the overhead wire method of the present invention,
Since the stress applied during the overhead wire work cannot remain in the optical fiber inside the optical fiber composite overhead wire, the abnormal stress may occur due to the superposition of stress caused by expansion and contraction due to the temperature difference of the wire. Moreover, if the electric wire is formed in a bundle winding state in the vicinity of the end portion and connected to the connection box, it is possible to exert a sufficient friction braking effect and a stress dispersion effect in the bundle winding portion, which may be caused by the temperature difference. Even if the optical fiber expands due to thermal expansion and contraction of the wire, there is no risk that the expansion will be accumulated at a specific position of the wire connection, and the optical fiber is bonded and fixed at the end by sufficient stress relief. You can also use the method
In the optical fiber composite overhead ground wire in an overhead wire state, it is significant that the damage due to the abnormal stress of the optical fiber can be completely eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of the vicinity of a junction box in an overhead wire according to the present invention.

FIG. 2 is a sectional view showing an embodiment of an optical fiber composite overhead ground wire.

FIG. 3 is an explanatory view showing a state in which an optical fiber composite overhead ground wire is extended by a hanging metal method.

FIG. 4 is an explanatory view showing a state of drawing the wire.

FIG. 5 is an explanatory view showing a state of drawing the wire.

FIG. 6 is an explanatory diagram showing an example in which stress is released from an optical fiber.

FIG. 7 is an enlarged sectional view of a P part in FIG.

FIG. 8 is a diagram showing a relationship between tension and elongation of an optical fiber composite overhead ground wire. 1 Optical Fiber Composite Overhead Ground Wire 1a Optical Fiber 1b Pipe 1c Elementary Wire 2 Bundle Winding Part 3 Junction Box 4 Fixing Part 5 Steel Tower Angle 10 Drum 11 Suspension Wheel 12 Main Rope 13 Winch

Claims (5)

[Claims] 1. An optical fiber composite aerial ground wire, in which an optical fiber is slidably accommodated in an accommodation chamber provided in the aerial ground wire, is extended between steel towers, and stress applied to the optical fiber in the overhead wire work. An optical fiber composite overhead ground wire extension method in which an end portion is connected to a junction box after the optical fiber is released by sliding the optical fiber. 2. The overhead wire method according to claim 1, wherein after the completion of the overhead wire, the end portion of the electrical wire is stretched in a straight line to be in a free state so that the sliding of the optical fiber is promoted to release the stress. 3. The overhead wire method according to claim 1, wherein the optical fiber is artificially pushed into the inside from the end portion of the electric wire to promote sliding of the optical fiber and release stress. 4. An overhead wire method according to any one of claims 1 to 3, wherein the electric wires are formed in a bundle winding state in the vicinity of the junction box. 5. The overhead wire method according to any one of claims 1 to 3, wherein after the stress releasing treatment, the end portion of the optical fiber is adhesively fixed to the accommodation member of the optical fiber.