JPH07262837A - External damage detecting metal sheath power cable - Google Patents

Abstract

PURPOSE:To realize a preventive process for the position where a corrosion proof layer is received with external damage or an impact, or the position where the corrosion proof layer has a possibility to receive an external damage, by providing conductive projections on a metal sheath, and providing an insulating tape and a conductive tape in order thereover. CONSTITUTION:External damage detecting sheath power cable 14 has a structure in which conductive projections 8 are provided on a metal sheath 7, and an insulating tape 9, and a conductive tape 10 are provided in order on the metal sheath 7. When this power cable 14 receives an impact at an outside corrosion- proof layer 11 of the outermost layer, and the layer 11 is deformed, the conductive layer 10 and the insulating layer 9 are also deformed, the conductive projections 8 bite into the insulating layer 9 so as to reduce the insulating property of the layer 9, and an alarm device 13 is operated. As a result, it is detected that the cable 14 received an impact by a dropping substance or the like. The alarm device 13 is operated naturally when the cable receives the external damage reaching the metal sheath 7, but the alarm device 13 is operated even though the cable 14 receives the external damage but the outermost corrosion proof layer 11 does not receive the damage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in power cables, especially metal sheath power cables.

[0002]

2. Description of the Related Art A cross-sectional view of a conventional metal sheath power cable is shown in FIG. The conventional metal sheath power cable 14 is
When the cable is laid on the upper layer, the conductor 1, the inner semiconductive layer 2, the insulator 3, the outer semiconductive layer 4, the cushion layer 5, and the semiconductive tape 6 are formed in this order from the inside of the cable. A metal sheath 7 is provided in order to prevent the installed cable from being damaged by falling objects,
Further, an anticorrosion layer 11 is provided to prevent the metal sheath 7 and the like from corroding.

As described above, the metal sheath power cable is provided with the outermost corrosion protection layer of the cable, and the corrosion protection layer is damaged when the cable is laid or when the laid cable is dropped. In order to prevent this, the rubber or plastic material is sufficiently thick and strong and is layered so that normal damage does not result in external damage reaching the metal sheath of the cable.

However, the damage received by the anticorrosion layer is deep or spreads for a long period of time, and finally corrodes the metal sheath,
It may cause insulation breakdown of the cable. Therefore, a means that can detect even a wound that does not reach the metal sheath is desired.

In Japanese Utility Model Publication No. 46-11000, the structure of a metal-sheathed electric power cable is formed on a (inner) anticorrosion layer of the cable, an intermediate electrode layer made of semiconductive rubber or semiconductive plastic material, and further thereon. As a structure with an outer anticorrosion layer on the outer anticorrosion layer, the outer anticorrosion layer received damage from the electrical damage that occurred at the scratched part by applying a high voltage between the intermediate electrode layer and the ground. It has been proposed to be able to detect trauma. When the trauma reaches the intermediate electrode layer and the intermediate electrode layer and ground are low-resistance grounded, the DC voltage method, Pearson inspector, and Murray loop method are introduced as the method for detecting the position. ing.

In Japanese Patent Publication No. 56-35082, for example, the structure of a metal sheath power cable is divided at regular intervals on the (inner) anticorrosion layer of the cable, and grounded at that location via a predetermined resistance element. The conductive wire having the above structure is arranged, and the metal sheath is grounded through a predetermined power source. When a short circuit occurs between the metal sheath and the conductive wire due to external damage,
It has been proposed to make it possible to detect the occurrence of a trauma and the position where the trauma occurs based on the current flowing between the metal sheath and the conductive wire and its value.

The above-described method is a method for detecting external damage that can be detected for the first time when external damage occurs on the outer anticorrosive layer, and the position at which the external damage occurs can be detected. It does not help to prevent damage to the environment around the place where the cable is installed.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to detect not only when the metal sheath power cable is damaged by the anticorrosion layer but also when it is subjected to a shock or the like. It is an object of the present invention to provide a wound-detection metal-sheath power cable capable of providing information capable of preventing damage to a place where the damage may occur but preventing the damage.

[0009]

SUMMARY OF THE INVENTION The foregoing objects are accomplished by providing a wound detection metal sheath power cable of the present invention.

That is, (1) A wound detection metal sheath power cable having a structure in which a conductive protrusion is provided on a metal sheath, and an insulating tape and a conductive tape are sequentially provided on the conductive protrusion.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and the construction and operation of a wound detection metal sheath power cable will be described below with reference to FIG. However, the present invention is not limited to the following description.

As shown in FIG. 1, a large number of conductive projections 8 are provided on the surface of a metal sheath 7 of a metal sheath power cable having a conventional structure (for example, as shown in FIG. 2), and an insulating layer 9 is provided on the outer layer thereof. Further, the conductive layer 10 is provided on the outer layer, and the outer anticorrosion layer 11 is provided on the outer layer.

When the metal sheath 7 is grounded at the far end as in the conventional case,
The conductive protrusion 8 is also grounded at the far end. The conductive layer 10 is also grounded at the far end via a predetermined power source 12 and an alarm device 13.

When the damage detection metal sheath power cable 14 of the present invention is impacted by the outermost anticorrosion layer 11 due to a fallen object or the like and the anticorrosion layer 11 is deformed (even if it is damaged,
The conductive layer 10 and the insulating layer 9 are also deformed (even if they are not received), the conductive protrusion 8 bites into the insulating layer 9, the insulation performance of the insulating layer 9 deteriorates, and the alarm device 13 operates to drop the cable 14. It is detected that the object is deformed due to an impact. The alarm device 13 will of course operate even if the cable 14 receives damage such as damage to the metal sheath 7 caused by a fallen object, etc.
The alarm device 13 is activated even when the outermost outer anticorrosion layer 11 is not damaged. Therefore, the wound detection metal sheath power cable of the present invention also has proactive detection capability.

In the case of the present invention, the DC voltage method for measuring the maximum potential position of the circuit due to the far-end grounding between the metal sheath and the conductive layer and the conduction between the metal sheath and the conductive layer generated by the projection, In addition, it is possible to know the damage location using the Pearson inspector method.

The damage detection sensitivity of the metal sheath power cable 14 of the present invention is as follows. The shape of the conductive protrusions 8, the thickness and material of the insulating layer 9, the voltage applied to the conductive layer 10 and the dynamics of the outer anticorrosion layer 11 are used. It depends on factors such as physical characteristics (e.g., susceptibility to deformation). If the sensitivity is set too high, the alarm device 13 will be activated depending on the impact received at the time of installing the cable, the weight of the cable, how to tighten the cleat, and the like, which is not preferable. Of course, if the alarm device 13 is not activated until the outer anticorrosion layer 11 is severely damaged, the preventive detection cannot be performed.

Therefore, the damage detection sensitivity of the damage detection metal sheath power cable 14 of the present invention is determined by adjusting the above-mentioned factors that affect the sensitivity of damage detection in consideration of the characteristics of the cable, the environment of the installation environment and the like. It

Insulating layer 9 which serves as a factor for adjusting the sensitivity of external damage detection,
The conductive layer 10 and the outer anticorrosion layer 11 can be installed locally by using an insulating tape, a semiconductive tape or the like in consideration of the situation of the installation environment.

[0019]

As is apparent from the above description, the damage detection metal sheath power cable and apparatus of the present invention can detect damage caused by a fallen object and prevent insulation breakdown of the cable.

[Brief description of drawings]

1 is a cross-sectional illustration of a wound detection metal sheath power cable and device of the present invention.

FIG. 2 is a cross-sectional view of a conventional metal sheath power cable.

[Explanation of symbols]

 1 conductor 2 inner semiconductive layer 3 insulator 4 outer semiconductive layer 5 cushion layer 6 semiconductive tape 7 metal sheath 8 conductive projection 9 insulating layer 10 conductive layer 11 anticorrosion layer 12 power supply 13 alarm device 14 injury detection metal sheath Power cable

Claims (1)

[Claims] 1. A metal sheath power cable having a structure in which a conductive protrusion is provided on a metal sheath, and an insulating tape and a conductive tape are sequentially provided on the conductive protrusion, and the damage detection metal sheath power cable.