JPS6227682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-metallic optical cable in which the harmful effects of moisture, moisture, etc. can be detected.

As is generally known, since an optical fiber is made of a dielectric material and is non-conductive, it has the characteristic that signals and other signals are not affected at all even when placed in a high electromagnetic field.

In addition, when converting these optical fibers into cables, it is possible to construct so-called non-metallic optical cables that do not use any metal at all.
Such an optical cable has a feature that it is easy to handle when installed in a high potential location.

However, due to its structure, non-metallic optical cables cannot use the metal laminate sheath used in conventional electric cables, and the sheath structure cannot be completely waterproof.

If moisture were to enter the sheath, the moisture would also enter the optical fiber disposed within the sheath, leading to an increase in optical transmission loss of the optical fiber.

Conventionally, in order to solve this problem, the cable sheath was filled with a suitable dry gas or compound, but when used for a long period of time, cracks could occur in the cable sheath due to the pressure of the sealed gas. Otherwise, the cable sheath deteriorated due to the migration phenomenon when the compound penetrated into the cable sheath and migrated, resulting in the problem of water absorption and moisture absorption.

In view of the above-mentioned problems, the present invention is designed to take measures against water absorption, moisture absorption, etc. by providing the optical cable itself with a moisture detection function. do.

FIG. 1 shows one embodiment of the present invention. In this embodiment, a plurality of coating layers 1 having a desired number of coating layers 1, such as a primary coating made of plastic and a secondary coating, are used. The cable optical fibers 2, 2, 2, . It is installed inside 4. To describe the embodiment in more detail, the optical fibers 2, 2, 2, .
They are arranged in an enclosing space (center space) of 2, 2....

On the other hand, in the embodiment shown in FIG.
The linear sensor 3 is arranged in the space created between the sheath 4 and the sheath 4.

In the above, the linear sensor 4 disposed inside the sheath 4 may have a structure shown in FIGS. 3 and 4 or other configurations, but the main components of the sensor 3 are The expansion material 6 is made of an optical fiber (coated optical fiber may be used), gua powder (a natural product), or vegetable fiber, etc., which expands by absorbing water and moisture, and the through holes 7, 7, 7... provide moisture permeability and water permeability. plastic pipe with 8
It is.

In addition, an inextensible thread 9 made of glass filament or the like is provided in the inflatable material 6, and the inflatable material 6 is restrained from expanding and contracting in the longitudinal direction, and expands and contracts well only in the radial direction. .

The linear sensor 3 shown in FIGS. 3 and 4 is constructed by wrapping an inflatable material 6 in a spiral around the outer periphery of a sensing element 5, and placing a pipe 8 on top of the inflatable material 6.

In each embodiment of the present invention, the linear sensor 3 shown in FIGS. 3 and 4 is housed inside the sheath 4 of the non-metallic optical cable shown in FIGS. When moisture occurs or enters, the expansion material 6 of the wire sensor 3 absorbs it and expands, and the expansion material 6 presses the detection element 5 made of optical fiber, causing microscopic This will cause bends (causing increased transmission loss).

Therefore, when an optical signal is passed through the detection element 5 and the transmission status of the signal is monitored, water content or high humidity inside the cable can be detected due to a level drop on the receiving side, and measures to be taken to deal with this can be immediately taken. Be able to take classes.

Note that in the above-described linear sensor 3, there may of course be an embodiment in which the non-stretchable thread 9 of the inflatable material 6 is omitted; It's okay.

Further, the above-mentioned inflatable material 6 interposed between the sensing element 5 and the pipe 8 may be arranged in a plurality and longitudinally along the outer periphery of the sensing element 5. In this case, each of the inflatable materials 6, 6, 6... may have different expansion rates, or may have different cross-sectional diameters.

Furthermore, the entire circumference of the sensing element 5 may be covered with a pipe-shaped inflatable material 6 of unequal thickness.

As explained above, the non-metallic optical cable according to the present invention includes an optical fiber for the cable and a non-metallic type linear sensor for detecting water absorption and moisture absorption inside the sheath, and the non-metallic type linear sensor includes: A detection element made of optical fiber,
It is characterized in that it comprises an inflatable material having water absorbing and hygroscopic properties, and the inflatable material is in contact with the outer periphery of the sensing element.

Therefore, in the case of the non-metallic optical cable according to the present invention, the influence of moisture, moisture, etc. can be detected through the non-metallic type linear sensor, and it is convenient to detect and alarm such a situation.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional side views showing various embodiments of the non-metallic optical cable of the present invention, and FIG.
FIG. 4 is a longitudinal sectional front view and a longitudinal sectional side view of the filament sensor in the same as above. 2... Optical fiber, 3... Non-metallic linear sensor, 4... Sheath, 5... Sensing element, 6...
...Inflatable material, 7...Through hole, 8...Pipe, 9...Inextensible thread.

Claims (1)

[Scope of Claims] 1. An optical fiber for a cable and a non-metallic type linear sensor for detecting water absorption and moisture absorption are housed in a sheath, and the non-metallic type linear sensor has a detection element made of an optical fiber and a non-metallic type linear sensor for detecting moisture absorption. 1. A non-metallic optical fiber comprising: an expandable material having water-absorbing properties and hygroscopic properties, and the expandable material is in contact with the outer periphery of a sensing element. 2. The non-metallic optical fiber according to claim 1, wherein the non-metallic type linear sensor is interposed between the outer periphery of the cable optical fiber and the inner periphery of the sheath. 3. The non-metallic optical fiber according to claim 1, wherein the non-metallic type linear sensor is interposed in an enclosed space formed by a plurality of cable optical fibers. 4. The non-metallic linear sensor according to any one of claims 1 to 3, wherein the sensing element and the expansion material are housed in a moisture-permeable pipe and are in contact with each other. Metallic optical fiber. 5. The non-metallic optical fiber according to any one of claims 1 to 4, wherein the expansion material is longitudinally attached to the outer periphery of the sensing element. 6 Claims 1 to 4, in which the inflatable material is spirally wound around the outer periphery of the sensing element.
3. The non-metallic optical fiber according to any one of paragraphs. 7. The non-metallic optical fiber according to any one of claims 1 to 6, wherein the expandable material is long and has a circular cross section. 8. The non-metallic optical fiber according to any one of claims 1 to 6, wherein the expandable material is long and has a circular cross section. 9 Claims 1 to 8, in which the expandable material has an expandability in the direction of expanding its cross-sectional diameter.
3. The non-metallic optical fiber according to any one of paragraphs. 10 Claim 4 in which the pipe has a through hole
Non-metallic optical fiber as described in Section 1.