JPH06109938A - Optical composite electric power cable - Google Patents

Abstract

PURPOSE:To prevent an optical fiber from having its edge broken and disconnecting at the optical fiber connection part of the optical composite electric power. CONSTITUTION:While end parts of two containing tubes 1 across the connection part 3 of optics fibers 2 are linked to each other, a two-split pipe 4 made of metal, FRP plastic, etc., is adhered with an adhesive and arranged. The two-split pipe 4 is divided into two halved members along a plane passing the center axes. The fiber connection part 3 is sandwiched between those two halved members to assemble the two-split pipe 4, whose end parts are both adhered to the end part peripheral surfaces of the respective containing tubes 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical composite power cable provided with an optical fiber used for temperature monitoring of an electric power cable and, more particularly, to an optical composite power cable having an optical fiber connecting portion provided in the middle of the power cable. .

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing an optical composite power cable. This optical composite power cable has a conductor 11, a semiconductive layer 12, and a cross-linked polyethylene (XLPE:
Insulator layer 13 made of CrossLinked Poly-Ethlene),
Semi-conductive layer 14, shield layer 15 formed by winding Cu wire
The anticorrosion layer 16 is coaxially arranged. Also,
Outside the anticorrosion layer 16, one or a plurality of storage tubes 17 are provided.
Is provided along the longitudinal direction of the cable, and an optical fiber (not shown) is housed in the housing pipe 17. The power cable is usually one power cable obtained by bundling three cables for three phases.

By the way, in a power cable, a so-called hot spot in which the temperature partially rises may occur due to a local difference in thermal resistance and a difference in surrounding environment. Although depending on the material of the insulating layer, when the temperature of the power cable exceeds 80 to 90 ° C., the electrical characteristics of the insulating layer are deteriorated, and an accident such as a landslide is likely to occur. When the insulating layer is cross-linked polyethylene, about 90 ° C. is said to be the maximum allowable temperature. Generally, the power cable is limited to a temperature (for example, 60 ° C. or lower) which is sufficiently lower than the maximum allowable temperature of the insulating layer during use.

In addition, usually, in the electric power cable, two or three lines are laid at the same time in order to ensure safety. And by switching the line at the time of inspection or accident,
Prevents power outages. When a landslide occurs, the location of the accident point will be identified, the line at the accident point will be disconnected from the substation, and the maintenance personnel in charge of the area will be dispatched. Therefore, it is necessary to specify the location of the accident point as soon as possible.

The Murray loop method and the pulse radar method are known as methods for detecting an accident point in a power cable not provided with an optical fiber. The Murray loop method is a method of forming a Wheatstone bridge circuit with a power cable and a resistance element, detecting a resistance value of an accident cable, converting the resistance value into a distance, and detecting a distance to an accident point.
In addition, the pulse radar method is a method in which a high voltage is applied to an accident cable to cause discharge at the accident point, the pulse generated at the accident point at that time is detected, and the distance from the pulse propagation time to the accident point is detected. Is.

However, both the Murray loop method and the pulse radar method have a drawback that it takes a long time from the occurrence of an accident to the specification of the position of the accident point because it takes time to prepare before starting the measurement. .

On the other hand, in the optical composite power cable, the optical fiber acts as a temperature sensor utilizing the fact that the intensity of Raman scattered light depends on temperature, and is used for temperature monitoring of the power cable. By using the optical fiber as the temperature sensor, the temperature can be monitored over the entire length of the power cable, and the occurrence of the hot spot can be detected. The optical fiber is also used to set the usage time of each line by measuring the time until the temperature of the cable reaches a predetermined temperature when a current is applied to the power cable.
Further, this optical fiber is also used when the location of the accident point is specified when a landfall occurs. That is, when a landslide occurs, arc discharge occurs between the conductor and the shield layer, the insulator melts, and gas is generated in the sealed space. When this gas explodes, the temperature rises locally. Also,
The temperature rises due to the arc heat, and the gas reacts with O ₂ to generate a flame and the temperature rises locally. The optical fiber can detect these temperature rises and identify the position of the accident point. The optical composite power cable has an advantage in that the temperature can be monitored over the entire length of the power cable, so that the time from the occurrence of a landslide to the location of the accident point can be shortened.

In the conventional optical composite power cable, after the power cable is laid, the optical fiber is arranged along with the power cable, but the length of the cable that can be wound on one drum is several hundred m. Therefore, when the laying length of the power cable is long, it is necessary to connect the optical fiber in the middle of the cable. FIG. 4 is a schematic diagram showing an optical fiber connection portion of a conventional optical composite power cable.

The optical cable 21 is pulled out from the end portion of each storage tube and is joined to each other, and the extra length is stored in the box 22.

[0010]

However, in the conventional optical composite power cable having the optical fiber connecting portion, since the mechanical strength (especially bending rigidity) between the optical fiber and the storage tube is greatly different, the end portion of the storage tube is greatly different. However, there is a problem that the optical fiber is easily bent and the transmission loss is easily increased. If the corner of the optical fiber is extremely bent, the optical fiber may be broken. A protective tube having a larger outer diameter than that of the storage tube and made of the same material as that of the storage tube may be fitted between the ends of the two storage tubes sandwiching the optical fiber connection portion, and the protection tube may be welded to the storage tube. is there. However, in this case, there is a drawback that a welding device is required and a heat insulating measure for the optical fiber is required, which makes the construction on site complicated.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an optical composite power cable which is easy to construct and can prevent corner breakage and disconnection in an optical fiber connecting portion. To do.

[0012]

An optical composite power cable according to the present invention is an optical composite power cable comprising a power cable and an optical fiber housed in a housing pipe provided along the power cable. 2 drawn out from each end of the two storage tubes separated in the longitudinal direction of the cable
An optical fiber connection part formed by connecting two optical fibers,
Both end portions thereof are bonded to the end portions of the two storage pipes, and two split pipes for storing the optical fiber connection portion are provided inside thereof.

[0013]

In the present invention, the two split pipes whose both ends are bonded to the respective ends of the two storage pipes sandwiching the optical fiber connection portion (the two split pipes are divided into two half-split members by a plane parallel to the central axis thereof). Pipe) is provided. That is, in the optical composite power cable according to the present invention, after connecting two optical fibers to each other, the optical fiber connecting portion is sandwiched by the two half members to assemble two split pipes, and the two split pipes are assembled. Adhere both ends of the to the peripheral surface of the end of the storage tube. Therefore, the optical fiber pulled out from the housing pipe for connection is mechanically protected by the two split pipes, local stress concentration can be avoided, and the optical fiber can be prevented from being bent or broken. it can.

The material of the two-split pipe is not particularly limited, but it is preferable that it is the same as the storage pipe or has the same bending strength as the storage pipe.

[0015]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an optical fiber connecting portion of an optical composite power cable according to an embodiment of the present invention.

The storage tube 1 is arranged in advance along any layer of the power cable and in a spiral shape with respect to the central axis of the cable, and the optical fiber 2 is stored inside thereof. In the vicinity of the optical fiber connection portion, two storage tubes 1 are separated from each other in the longitudinal direction of the power cable, and the optical fibers 2 drawn out from each storage tube 1 are optically connected to each other. The two split pipes 4 are provided by connecting the ends of the two storage pipes 1 sandwiching the optical fiber connection portion 3 to each other with adhesives on the peripheral surface of the storage pipe 1. This two-split tube 4 is shown in a perspective view in FIG.
It is configured by combining two half members 4a and 4b. The two-split pipe 4 is formed of the same material as the storage pipe 1 or metal, FRP, plastic, or the like having the same bending strength as the storage pipe.

That is, in the present embodiment, after connecting the two optical fibers 2 to each other, the two half members 4a, 4 are
The optical fiber splicing part 3 is sandwiched by b and the two split tubes 4
Then, both ends of the two split pipes 4 are bonded to the end peripheral surface of each storage pipe 1. Therefore, the two split tubes 4 mechanically protect the optical fiber of the portion pulled out from the storage tube 1, and it is possible to avoid local concentration of stress on the optical fiber. As a result, it is possible to prevent breakage and breakage of the optical fiber. Further, the present embodiment, compared with the conventional optical fiber connection portion processing method of welding the protection tube to the storage tube,
The processing of the optical fiber connection part is easy and the workability is excellent.

[0019]

As described above, according to the present invention, since the two split pipes having their both ends bonded to the peripheral surfaces of the two storage pipes sandwiching the optical fiber connecting portion are provided, the storage pipes are provided. The part of the optical fiber that is pulled out from the optical fiber is mechanically protected by the two split tubes, so that the optical fiber can be prevented from being bent and broken. Further, there is an effect that the workability of the processing of the optical fiber connecting portion is excellent as compared with the conventional method of processing the optical fiber connecting portion which welds the protective tube to the storage tube.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an optical fiber connection portion of an optical composite power cable according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a half-divided member forming a two-split tube.

FIG. 3 is a cross-sectional view showing an optical composite power cable.

FIG. 4 is a schematic diagram showing an optical fiber connection portion of a conventional optical composite power cable.

[Explanation of symbols]

 1, 17; Storage tube 2; Optical fiber 3; Optical fiber connection part 4; Two split tubes 4a, 4b; Half split member 11; Conductors 12, 14; Semiconductive layer 13; Insulator layer 15; Shielding layer 16; Anticorrosion layer

Claims (1)

[Claims] 1. An optical composite power cable comprising a power cable and an optical fiber accommodated in a storage tube provided along the power cable, wherein each end of two storage tubes separated in the longitudinal direction of the power cable. And an optical fiber connecting part formed by connecting two optical fibers drawn out from the two parts, and both ends thereof are adhered to the ends of the two storage pipes, and the optical fiber connecting part accommodates the optical fiber connecting part inside thereof. An optical composite power cable having a tube.