JPS60238747A - Cable for detecting moisture absorption - Google Patents

Abstract

PURPOSE:To discriminate efficiently a moisture absorbing condition by using an optical fiber consisting of a material contg. metallic elements such as Na and K, forming a moisture permeable covering thereon without subjecting the fiber to a surface treatment for water-proofing to form a moisture absorption sensor and incorporating such sensor into a cable. CONSTITUTION:The optical fiber having a core 41 and a clad 42 and contg. the metallic elements such as Na and K is used. The moisture permeable covering 43 is formed thereon without subjecting the fiber to the surface treatment for water-proofing to manufacture the moisture absorption sensor 4. Such sensor is incorporated integrally with an intervening material 2 into a cable sheath 3, thereby constituting the cable. Light is made incident onto the sensor 4 from one end thereof by a light source 5 and is monitored by a photodetector 6 provided at the other end. The adequate and efficient discrimination of the moisture absorbing condition of a communicating cable, etc. is thus made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a moisture absorption detection cable incorporating a moisture absorption sensor.

[Background of the Invention] Currently, power cables and communication cables are widely used and serve essential social functions in modern life. Needless to say, these cables require a high degree of performance stability and reliability.

The performance of cables that play such an important role
(Moisture intrusion into the cable is one of the causes of failures. To prevent this, a strong coating is usually applied, but in the unlikely event that moisture intrudes), it can be detected or extended. There was no suitable method for predicting performance degradation due to the intrusion of minute amounts of water during this period.

In other words, the so-called humidity lenses that can detect moisture or humidity include electrical resistors using 1icl, carbon film, vapor-deposited film, porous aluminum oxide, magnetite 1-Tloid, nickel ferrite, tin oxide, titanium oxide, ceramics, etc. A number of humidity sensors have already been developed and put into practical use, such as humidity sensors that utilize micro-fluid propagation loss, but all of these conventional humidity sensors operate within a limited area near where the sensor is installed. In order to detect the humidity inside a long object such as a lightning cable or communication group, it is necessary to install a large number of humidity sensors along the longitudinal direction. It is not suitable as a moisture absorption sensor for power cables or communication coolers.

[Object of the Invention] In view of the above situation, an object of the present invention is to provide a practical moisture absorption detection cable incorporating a moisture absorption sensor.

[Summary of the Invention 1 The present invention uses an optical fiber made of a material containing metal elements such as Na and Ni, coats it with a moisture-permeable coating without performing waterproof surface treatment, and uses it as a moisture absorption sensor. This is built into the cable.

Embodiment 1 of the Invention The configuration of the present invention will be specifically explained with reference to drawings showing embodiments.

In Figure 1, 1 is the wire core of the power cape, 2 is the intervening wire, and 3 is the wire core of the power cape.
is a sheath, and a moisture absorption sensor 4 is integrated inside this sheath 3.

The moisture absorption sensor 4 is constructed by applying a coating 43 to a glass optical fiber having a core/1.1 and a cladding 42, as shown in FIG.

The glass optical fiber contains metal elements such as Na and Ni, and the coating 43 is made of a porous plastic deck with good permeability.

As shown in FIG. 3, a couple in which such a moisture absorption sensor 4 is integrated is configured such that light is inputted from one end of the optical fiber of the moisture absorption sensor 4 by a light source 5, and a light receiving device 6 is installed at the other end. monitor the optical transmission status.

If water enters the couple sheath 3 for some reason to prevent a defect from occurring in the cable sheath 3, the intervention 2
Since the optical fiber coating placed here is moisture permeable, moisture will reach the optical fiber.

As mentioned above, some optical fibers contain metal elements such as Na, etc., which easily causes chemical and physical changes that increase light transmission loss.

This situation is determined by the 8S arithmetic device 7 connected to the light receiving device 6 and displayed on the display device 8.

Furthermore, even if a large amount of water does not enter the cable from the outside, the insulation of the cable and the cross-linked polyethylene used in step 1) may deteriorate due to accumulated moisture when used in a high humidity atmosphere for a long period of time. Although it is well known that deterioration of performance occurs, the moisture absorption sensor used in the present invention is also capable of detection based on cumulative moisture absorption, so it is reasonable to use this to detect deterioration of insulation performance of cables.

Note that the coating of the optical fiber of the moisture-absorbing lens is not limited to porous plastic, but any moisture-permeable coating can be used regardless of its type. .

Regarding the material of the optical fiber, in addition to the above-mentioned glass containing metals such as Na, Na, etc.

Plus deck b containing metal elements such as K can be used.

Furthermore, it goes without saying that by devising the light source 5, it is also possible to detect moisture absorption locations on the cable.

[Advantageous Effects of the Invention 1] As explained above, the hot water absorption detection cable of the present invention can appropriately determine the moisture absorption status of long power multiples, communication couples, etc. with a simple configuration, and has practical utility value. is extremely large.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of one embodiment of the present invention, and FIG.
The figure is an explanatory cross-sectional diagram showing an example of a moisture absorption sensor used in the present invention, and FIG. 3 is an explanatory diagram of a system using the present invention. 1: Cable core, 2: Interposition, 3: Sheath, 4: Moisture absorption sensor 4), /11: Optical 7P fiber = 1 horn, /! 2: Optical fiber cladding, 43: Moisture permeable coating.

Claims (1)

[Claims] A moisture absorption detection couple, characterized in that an optical fiber containing a metal element such as Na or Ni is coated with a moisture permeable coating and is incorporated inside a cable sheath.