JPH06338227A - Detection cable - Google Patents

Abstract

(57) [Abstract] [Purpose] Despite its simple structure, it can immediately detect the damage of the outer cover and the inundation caused by the outer cover damage, and facilitates the polarity test. [Structure] A plurality of electrically insulated conductive plastic strips 7 are provided inside a plastic jacket 3 covering a cable core 1. The conductive plastic strips 7 have the same cross section in the longitudinal direction of the cable and are arranged at substantially equal intervals in the circumferential direction. Adjacent conductive plastic strips 7 are color-coded so that they can be distinguished. When the outer cover is provided in multiple layers, a plurality of conductor strips are provided so as to be exposed on the inner surface of the outermost outer cover. Due to the change in the electrical characteristics between the conductive plastic strips 7, external damage and water infiltration can be detected at the level of the envelope.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection cable for detecting running water and preventing running water when the cable is flooded due to external damage or the like. Regarding the improved one.

[0002]

2. Description of the Related Art When an outer cover is damaged due to some kind of external damage after the cable is laid, water is leaked from the damaged part into the cable core to cause insulation failure. Normally, when a fault due to water intrusion is discovered, it is inundated into the cable core, and the abnormality is noticed only when the used circuit becomes a disconnection or a line interference. For this reason, it takes a long time to find a failure, the damage to the cable becomes great, and the cost required for restoration becomes large.

Therefore, conventionally, in order to solve such a problem, a detecting conductor is provided in the cable, and a change in the electrical characteristics between the conductors causes damage to the cable before the damage to the cable becomes significant. A detection cable for detecting running water is known. FIG. 6 shows a typical example of the detection cable.
This is one in which two cores of the alarm lines 4 and 4 are embedded in a very shallow place inside the cable core 1. The two alarm wires 4 and 4 are sensing wires for detecting water intrusion, and water intrusion is detected at the surface level of the cable core 1 by measuring the insulation resistance between the two wires. This two-core alarm line 4, 4
Are embedded at both ends on the diameter of the cable core 1. The surface of the cable core 1 in which the alarm wire 4 is embedded is usually covered with a shielding tape 2 and a plastic jacket 3 is provided on the outside thereof.

An upper winding tape (not shown) is wound on the outside of the shielding tape 2, and a plastic jacket 3 is placed on the outside thereof.
There is also a structure.

[0005]

However, the above-mentioned conventional detection cable has the following drawbacks.

(1) In the case of flooding due to external damage to the jacket 3, since the shielding tape 2 is wound around the cable core 1, the flooding is blocked and it takes time to reach the alarm line 4. Therefore, it takes a long time from the occurrence of inundation to the detection, and the damage due to inundation and the cost required for restoration have not been improved so much. Further, there is a similar problem when the shielding tape 2 is provided with an upper tape.

(2) Further, since the alarm wire 4 is located at both ends on the diameter, the water cannot be detected unless the entire surface of the cable core is soaked, and it takes a long time from the occurrence of the water to the detection.

(3) The structure is complicated because it is necessary to make a hole in the cable core 1 and insert the alarm wire 4 therethrough.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a detection cable having a simple structure and capable of immediately detecting damage to the outer cover or water immersion due to the outer cover damage.

[0010]

SUMMARY OF THE INVENTION A detection cable of the present invention comprises a plurality of conductor strips having the same cross section in the longitudinal direction and arranged at substantially equal intervals in the circumferential direction inside an outer cover covering a cable core. Is provided to detect changes in electrical characteristics between these conductor lines.

Further, the detection cable of the present invention has a plurality of jackets having the same cross section in the longitudinal direction and arranged at substantially equal intervals in the circumferential direction at a shallow portion of the jacket covering the cable core when viewed from the cable surface. A conductor strip is provided, a conductor layer covering the cable core is provided in a deep portion of the jacket, and changes in electrical characteristics between these conductor strips or between conductor strips and conductor layers are detected. .

In these cases, it is preferable that adjacent conductor strips are color-coded for the convenience of the electrical characteristic test.

Further, in the detection cable of the present invention, the jacket covering the cable core has at least a four-layer structure in which conductor layers and insulating layers are alternately laminated.

In the present invention, it is particularly preferable that the jacket or the insulating layer is made of plastic, and the conductor strip or the conductor layer is made of conductive plastic. Here, the conductive plastic is also called a conductive composite plastic molding material, and has an increased electrical conductivity by, for example, kneading an antistatic agent together with a surfactant into the plastic. The jacket in the present invention may include tapes wound around the cable core, and may be a multilayer without being limited to one layer.

Further, in the case of providing a plurality of outer jackets, a plurality of outer jackets, which are exposed on the inner surface of the outermost jacket, have the same cross section in the longitudinal direction and are arranged at substantially equal intervals in the circumferential direction. Conductor strips are provided to detect changes in electrical characteristics between these conductor strips.

[0016]

[Function] If a conductor strip is provided on the inside of the jacket instead of the inside of the cable core, it is possible to detect external damage before it reaches the cable core. To do. Further, when a plurality of conductor strips are provided in the circumferential direction, a change in electrical characteristics between adjacent conductors can be measured, so that it is possible to detect when the range of injury is small and also the location of injury. .

Further, if a plurality of conductor strips arranged in the circumferential direction are provided in a shallow portion of the outer cover and a conductor layer is provided in a deep portion of the outer cover, the conductor having a characteristic change may be damaged. Can detect up to the depth.

If the conductor strips in the circumferential direction are color-coded, it is convenient when the polarity is changed in the electrical characteristic test.

Further, if the outer cover is formed by alternately laminating the conductor layers and the insulating layers, the ability to detect water immersion due to the occurrence of external damage is improved.

Further, if a plurality of conductor strips are provided on the inner surface of the outermost jacket, the damage to the outer skin can be immediately detected.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first to fourth embodiments of the detection cable of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a sectional view of a detection cable according to the first embodiment. In the detection cable, an insulative shielding tape 2 is applied on the central cable core 1, and an insulative plastic jacket 3 is provided as a jacket. Inside the plastic jacket 3, a conductive plastic strip 7 is provided on the shielding tape 2. This conductive plastic strip 7 has the same cross section in the longitudinal direction of the cable,
In addition, a plurality of cables are arranged at substantially equal intervals in the circumferential direction of the cable. Although the cross-sectional shape of the conductive plastic strip 7 is a quadrangle in the illustrated example, it may be any shape such as a circle or a triangle. The conductive plastic strips 7 are electrically isolated from each other. When the conductive plastic strip 7 is provided so as to float above the shielding tape 2, the shielding tape 2 may be a metal tape. Further, in the drawing, the hatching is shown alternately, but the adjacent conductive plastic strips 7 are colored in two colors. It is necessary to change the polarities between adjacent colors in an electrical test (insulation resistance test or continuity test) performed when water is detected, and to distinguish between the two colors, this discrimination is made easier.

According to this, since the conductive plastic strip 7 is provided inside the jacket 3 to detect when the cable is submerged due to external damage or the like, the insulation resistance between the adjacent pieces is tested. By doing so, an abnormality can be detected at the stage of the jacket 3 before reaching the cable core 1. Therefore, the time from occurrence of flooding to detection can be made extremely short. As a result, the damage can be minimized, and the cost required for restoration can be reduced.

[Second Embodiment] FIG. 2 is a sectional view of a detection cable according to a second embodiment. The difference from the first embodiment of FIG. 1 is that the conductive plastic strip is provided in a shallower portion of the outer cover, and the conductor is also provided in a deeper portion of the outer cover. The basic structure of the cable is that a cable core 1 is provided with an insulative plastic jacket 3 as an jacket. And, having the same cross section in the longitudinal direction of the cable at the shallow portion of the jacket 3 when viewed from the cable surface,
Further, a plurality of electrically conductive plastic strips 8 which are arranged at substantially equal intervals in the circumferential direction and electrically insulated and separated are provided. Further, a conductive plastic layer 5 that covers the cable core 1 is provided in a deep portion of the outer cover. The conductive plastic layer 5 may be a metal tape around which the cable core 1 is wound.

Since the plurality of conductive plastic strips 8 in the shallow place are electrically insulated from each other, even if the outer cover 3 is damaged and water is flooded at a shallow level, the damage can be detected. Also, with this structure, it is possible to detect whether the external damage is of a shallow level or a deep level. For example, when there is conduction between adjacent conductive plastic strips 8, it can be judged that the damage is shallow, and the conductive plastic strips 8 at the shallow place are considered to be damaged.
When there is conduction between the conductive plastic layers 5 at deep places, it can be determined that the damage is deep.

[Third Embodiment] FIG. 3 is a sectional view of a detection cable according to a third embodiment. A major difference from the first and second embodiments is that each of the conductors is composed of a conductor layer continuous in the circumferential direction. The top of the cable core 1 is covered with a shielding tape 2, and the outer cover is covered with an electrically conductive plastic layer 10, an insulative plastic layer 11, an electrically conductive plastic layer 9, and an insulative plastic layer 11 in that order from the outermost surface toward the inside. In addition, conductive layers and insulating layers are alternately laminated to form a multi-layer. Two or more intermediate conductive plastic layers 9 may be provided between the insulating plastics 11, 11.

According to this, when the cable jacket is damaged and flooded, if the scratch reaches the conductive plastic layer 9 in the middle part of the jacket, the outermost conductive plastic layer 1
A flaw can be easily detected by a continuity test from the terminal between 0 and the conductive plastic layer 9 in the middle.

Especially when the cable is an important line, it can be said that it is common to the above-mentioned first to third embodiments. By additionally equipping the alarm circuit, the abnormality notification at the time of abnormality detection can be made. It will be possible. As a result, damage due to trauma can be minimized and recovery can be performed in a short time.

[Fourth Embodiment] FIG. 4 is a sectional view of a detection cable according to a fourth embodiment. This detection cable is provided with a three-layer jacket. That is, the two alarm lines 21, 2
Insulating shielding tape 23 on the cable core 22 including 1
Is applied to the outside of the shielding tape 23 and the upper tape 24
Has been applied. An insulating plastic jacket 25 is provided on the outside of the upper tape 24. On the inner surface of this plastic jacket 25 are four conductive plastic strips 2
6a to 26d are provided. The conductive plastic strips 26a to 26d are formed at the same time when the plastic jacket 25 is extruded. At the time of this extrusion molding, the conductive plastic strips 26a to 26d are molded so as to be exposed on the inner surface of the plastic jacket 25, and the plastic jacket 25 is damaged by the external damage.
5 and the water that has entered between the upper winding tape 24 and the winding tape 24 are directly contacted. This conductive plastic strip 26a
Properties of 26d are similar to those of the conductive plastic strip 7 of the first embodiment. The number of cables to be arranged is also set appropriately according to the conditions such as the size of the cable.

According to this, when the cable is submerged due to external damage of the jacket 25, the conductive plastic strips 26a to 26d provided inside the jacket 25 can immediately detect it. The same effect as the first embodiment is obtained.

The conductive plastic strips 26a to 26 are also provided.
Since d is molded at the same time as the extrusion molding of the plastic jacket 25, the molding is extremely simple.

Further, even if water is infiltrated from the end of the cable, it can be immediately detected by the alarm lines 21 and 21.

In the fourth embodiment, the cable core 22
Although the alarm lines 21 and 21 are provided in the above, as shown in FIG.
Only 26d may be provided. Also in this case, the same effect as described above can be exerted against the occurrence of water infiltration due to external damage or the like.

[0034]

【The invention's effect】

(1) According to the detection cable of claim 1, since the conductor strip is provided inside the jacket instead of the cable core,
When water is inundated due to external damage to the outer cover, an abnormality can be immediately detected. Moreover, since a plurality of conductor strips are provided in the circumferential direction,
Not only can a part of the flooded part be detected, but information such as the size and position of the wound can also be obtained from the conductor strip to be measured. Therefore, the damage can be minimized,
The cost required for restoration is low.

(2) According to the detection cable of the second aspect, since the conductor strip is provided in the shallow portion of the outer cover and the conductor layer is provided in the deep portion of the outer cover, the depth of the external damage can be detected.

(3) According to the detection cable of the third aspect, since the conductor strips in the circumferential direction are color-coded, it is convenient to change the polarity in the electrical test.

(4) According to the detection cable of the fourth aspect, when the cable jacket is damaged and flooded, if the scratch reaches the middle conductor layer of the jacket, the damage can be easily caused. Can be detected.

(5) According to the detection cable of the fifth aspect, since the conductor strip or the conductor layer is made of conductive plastic, the structure is simple, and the adhesiveness to the plastic jacket is good. , High reliability of the cable.

(6) According to the detection cable of the sixth aspect, since a plurality of conductor strips are provided on the inner surface of the outermost outer jacket of the multilayer jackets, the outer jacket is damaged. When water is flooded due to such reasons, an abnormality can be immediately detected.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a detection cable of the present invention.

FIG. 2 is a cross-sectional view showing a second embodiment of the detection cable of the present invention.

FIG. 3 is a transverse sectional view showing a third embodiment of the detection cable of the present invention.

FIG. 4 is a transverse sectional view showing a fourth embodiment of the detection cable of the present invention.

FIG. 5 is a transverse sectional view showing a modified example of the fourth embodiment.

FIG. 6 is a cross-sectional view of a conventional cable example.

[Explanation of symbols]

 1 Cable Core 2 Shielding Tape 3 Plastic Jacket 5 Conductive Plastic Layer (Conductor Layer) 7 Conductive Plastic Strip (Conductor Strip) 8 Conductive Plastic Strip (Conductor Strip) 9 Conductive Plastic Layer (Conductor Layer) 10 Conductive Plastic Layer (Conductor Layer) 11 Plastic Layer (Insulating Layer) 26a to 26d Conductive Plastic Strip (Conductor Strip)

Claims (6)

[Claims] 1. A plurality of conductor strips, which have the same cross section in the longitudinal direction and are arranged at substantially equal intervals in the circumferential direction, are provided inside an outer cover that covers the cable core. A detection cable that detects changes in characteristics. 2. A shallow outer cover for covering the cable core,
A plurality of conductor strips having the same cross section in the longitudinal direction and arranged at substantially equal intervals in the circumferential direction are provided, and a conductor layer covering the cable core is provided in a deep portion of the outer cover, and the conductor strips or the conductor strips are electrically conductive. A detection cable characterized by detecting a change in electrical characteristics between a body strip and a conductor layer. 3. The detection cable according to claim 1, wherein adjacent conductor strips are color-coded. 4. A detection cable, wherein an outer cover for covering the cable core has at least a four-layer structure in which conductor layers and insulating layers are alternately laminated. 5. The detection cable according to claim 1, wherein the jacket or the insulating layer is made of plastic, and the conductor strip or the conductor layer is made of conductive plastic. 6. A cable core having a plurality of jackets, a plurality of jackets having the same cross section in the longitudinal direction and arranged at substantially equal intervals in the circumferential direction, which are exposed on the inner surface of the outermost jacket of the jackets. The detection cable is characterized in that the conductor strips are provided, and changes in electrical characteristics between the conductor strips are detected.