JP3264862B2 - Transfer cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving cable used in an uninterruptible bypass method for overhead distribution lines and a method for detecting a disconnection of a shielding layer in the cable.

[0002]

2. Description of the Related Art A mobile cable is provided with a shielding layer on an outer semiconductive layer from the viewpoint of security and ensuring the performance of the cable. Usually, this shielding layer is 0.12mmφ ~ 0.20mmφ
It has a braided structure in which a small-diameter copper wire (metal wire) is woven, and the repeated bending, tension,
It is configured to withstand external forces such as twisting. For example, as shown in FIG. 7 (A), a plurality of small-diameter copper wires 15 are bundled to form a unit 16 and a cotton yarn 17, and the aggregates 16 are arranged in one direction and intersect therewith. In many cases, a weaving braid in which cotton yarn 17 is woven in the direction is used.

[0003]

However, the conventional moving cable has a problem that the breaking of the metal element wire in the shielding layer cannot be effectively detected.

[0004] If all the metal wires of the shielding layer are broken, the portion far from the broken portion is not grounded, which is very dangerous. Therefore, it is desired to detect the disconnection of some of the metal wires at the stage where the disconnection has occurred. At present, the most practical method for detecting this disconnection is to measure the resistance value of the shielding layer and estimate the state of decrease in the conductive metal wires from the change with time in the resistance value.

However, as shown in FIG. 7B, even if one of the small diameter copper wires 15 in the shielding layer is broken, a conduction path is formed via the adjacent small diameter copper wire, so that the resistance value is low. Hardly changes. All the metal wires in a certain assembly are broken, and the resistance value corresponding thereto only slightly increases. In addition, actually, when the cable is subjected to an external force such as bending or twisting, the braided structure is disturbed, and adjacent assemblies come into contact with each other somewhere in the longitudinal direction of the cable. Therefore, the conduction path of the shielding layer is maintained until almost all the assemblies are disconnected, and it is extremely difficult to detect an increase in the resistance value. Of course, there may be a case where the conduction path decreases and the resistance increases due to the disconnection of the wire of the shielding layer. Even in such a case, the change in the resistance value is slight, and it is difficult to accurately measure the resistance value on site.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide a moving cable and a disconnection detecting method which can easily detect even when a disconnection of a metal wire of a shielding layer occurs partially.

[0007]

According to the present invention, the above object is attained by combining a disconnection detection line, which can determine a disconnection by a continuity check, with each of a set of metal wires. That is, the moving cable according to the present invention is a moving cable having a braided structure shielding layer in which an aggregate of metal wires is woven, wherein at least one disconnection detection wire having an insulating coating on each of the aggregates is combined. It is characterized by doing.

The shielding layer has a structure in which an aggregate of metal wires is woven. For example, a plurality of aggregates are arranged in one direction,
One in which natural fibers such as cotton yarn or synthetic fibers such as polyamide resin are woven in a direction intersecting with the aggregate to form a cross-woven braid.

The aggregate is formed by arranging, bundling, or twisting metal wires. A thin copper wire is suitable as the metal wire.

The disconnection of the shielding layer is detected by checking the continuity of the disconnection detection line. The material for detecting the disconnection is not particularly limited as long as the conductor has an insulating coating. When the detection line is broken, it is sufficient if a conduction path is not formed via the adjacent metal element wire. For example, an enameled wire is preferable. In particular, standard products such as JIS 3202 are suitable.
Further, the method of combining the disconnection detection line and the metal element wire is not particularly limited. What is necessary is just to bundle and twist together with a metal strand.

The outer diameter of the disconnection detection wire is selected to be an optimum value so that the wire is disconnected at the same time as or earlier than the metal wire. When the outer diameter of the disconnection detection wire is d and the outer diameter of the metal wire is D, d / D is preferably 0.5 to 2.0. The disconnection of the shielding layer due to the external force during use of the cable includes both the one caused by ductile rupture and the one caused by fatigue rupture. The smaller the value of d for ductile rupture and the larger d for fatigue rupture, the easier the disconnection. The d / D is set to 0.5 or more in a use condition where ductile fracture is dominant, and is set to 2.0 or less in a use condition where fatigue fracture is dominant.

Further, according to the disconnection detecting method of the present invention, at one end of the cable, a resistor having a larger resistance value and an equal resistance value than the disconnection detection line is connected in series to each disconnection detection line, These resistors are connected in parallel to form a measurement point at one end, and at the other end of the cable, a disconnection detection line is connected in parallel to form a measurement point at the other end. The resistance value is measured between them, and the number of disconnection of the disconnection detection line is determined from the resistance value.

It is preferable that the resistance value of the resistor is about three digits larger than the resistance value of the disconnection detection line in the unit length cable.

Further, the resistance value between the conductor at one end of the cable and the measurement point at one end may be measured by connecting the measurement point at the other end to the conductor at the other end of the cable. In this case, disconnection detection can be performed only at one end of the cable.

Further, it is desirable to use a connector for connection between the disconnection detection line and the resistor. This facilitates connection between the disconnection detection line and the resistor, and disconnection detection of a plurality of cables can be performed with one set of the resistor.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a schematic perspective view showing the structure of the cable of the present invention. As shown, the cable of the invention comprises a shielding layer 2 on a core 1 and a sheath 3 thereon. The core 1 is composed of a conductor, an inner semiconductive layer, an insulating layer, and an outer semiconductive layer (all not shown) in order from the center.

Here, the shielding layer 2 is made of a tin-plated soft copper wire 4 (white thin wire), an enamel wire 5 (black wire) and a cotton yarn 6 (thick white wire).
It has a braided structure. A plurality of tin-plated soft copper wires 4 serving as metal wires and at least one enamel wire 5 are bundled to form an aggregate 7, and the aggregate 7 is defined as one unit. Then, the aggregate 7 is arranged in one of the clockwise and counterclockwise directions in the braid, and the cotton yarns 6 are arranged in the other, and the two are woven together to form a cross-woven braid. In the shielding layer, enamel wires of “the number of enamel wires combined into one aggregate × the number of aggregates” are woven. The total cross-sectional area of the metal wires may be selected to be a value necessary for flowing the current induced in the cable shielding layer to the ground.

When the cable is subjected to an external force and the breaking of the metal element wire in the shielding layer progresses, the enameled wire 5
Also breaks. Since the enamel wire 5 has an insulating coating, a conductive path is not formed via an adjacent metal element wire even if the wire is disconnected. Therefore, if the continuity check of each enamel wire 5 is performed, disconnection of the metal element wire can be reliably detected. This continuity check can be easily performed on site, unlike a precise resistance measurement.

More specifically, as shown in FIG.
Is preferably connected to the enamel wire 21 (disconnection detection wire) for measurement. That is, the resistor 22 is connected to each enamel wire 21 drawn out from one end of the cable 20, and these are connected in parallel to form a measurement point 23 at one end. Resistor used here
For 22, those having the same resistance value and sufficiently larger resistance value than the enamel wire 21 are used. On the other hand, the enamel wires 21 drawn from the other end of the cable are also connected in parallel to form a measurement point 24 at the other end. Then, a tester 25 is connected between the one-end measurement point 23 and the other-end measurement point 24 to read a change in the resistance value.

In most cases, the moving cable is used in a unit length of several meters to several tens of meters. In addition, the conductor wire of a normal moving cable has an outer diameter of about 0.18 to 2.0 mmφ. Therefore, the resistance value per disconnection detection line is about several mΩ / unit length to several tens mΩ / unit length.

Here, the enamel wires at both ends of the cable are simply connected together in parallel without using the resistor, and the resistance values at both ends are measured, and the number of enamel wire breaks is determined from the change in the resistance value. But it is actually difficult. In this case, the resistance value to be measured is too small, and the measurement error increases in a real field having only a simple tester.

Therefore, as shown in FIG. 2, a resistor 22 is connected to each enameled wire 21 and they are connected in parallel.
A resistance value (several Ω) that can be measured sufficiently with a simple tester
To several hundred Ω). As a result, the number of measurements required for the disconnection check can be reduced to one for one cable.

For example, for a cable having 19 enameled wires, if a resistor of 200Ω is connected to each enameled wire, the relationship between the number n of broken enameled wires and the parallel resistance R is R = 200 / (19−n) ) (Ω).

An example of the relationship between n and R is as follows. n (book) 0 1 2 3 ... 17 18 19 R (Ω) 10.5 11.1 11.8 12.5 ... 100 200 な ら ば With this value, a simple tester can measure with almost no error. The number of disconnections can be determined.

The resistance value of the resistor (for example, 200Ω)
Is sufficiently larger than the enameled wire (mΩ order)
The existence of the enamel wire can be ignored in the measurement. That is, in the method of the present invention, the same resistor can be applied regardless of the thickness of the disconnection detection line. The resistor connected to the disconnection detection line desirably has a resistance value that is at least about three orders of magnitude greater than the resistance value of the disconnection detection line. Considering availability, those having a resistance value of about 1Ω are preferable.

As shown in FIG. 3, if the conductor 31 of the cable 30 is used as a return line, a disconnection check can be performed only at one end of the cable 31. That is, the cable
The other end measurement point where the enameled wires 32 at the other end of 30 (the left side in FIG. 3) are collectively connected to the other end of the cable conductor 31. At one end of the cable, the resistor 33 connected to each enameled wire 32 is collectively formed to form a measuring point 34 at one end, and a tester 35 is connected between the measuring point 34 at one end and one end of the cable conductor 31 to form a resistor. The change in the value may be measured.

Further, as shown in FIG. 4, when a connector 46 is used to connect each enameled wire 42 and the resistor 43 at one end (right side in FIG. 4) of the cable 40 in addition to the configuration shown in FIG. The connection of 42 and 43 can be easily performed, and the continuity of a plurality of cables can be checked with one set of resistors.

As described above, it is possible to detect the disconnection that has occurred in the shielding layer before all the metal wires are disconnected. In other words, when a wire break occurs in the aggregate unit, only the enamel wire that was composited in the aggregate is broken, and the enamel wires in other aggregates are not broken, so the break in the metal element wire is partially The disconnection that has occurred in the shielding layer at the stage where it has occurred can be grasped.

Further, if the disconnection detection wire is made of a material and an outer diameter that can be disconnected earlier than the metal wire, and if the detection wire is detected to be disconnected, it is expected that the metal wire will be disconnected in the near future. Can be.

(Test Example) A bending test was performed on the cable having the above-described structure, and the state of disconnection of the metal wires and the state of disconnection of the enameled wire in the shielding layer were examined. As shown in FIG. 5, the test method is such that a predetermined length (shaded portion) of the cable 10 is fixed, the fixed portion is supported on the rotating shaft 11, and 10 kg is attached to the end of the cable.
Attach weight 12 of. Then, the cable was reciprocated in the range of 180 ° around the rotating shaft 11, and a cable having a radius of 50 mm was repeatedly applied to the cable 10 to examine the relationship between the number of times of bending and the resistance change of the shielding layer. Furthermore, the conduction of each enameled wire was checked, and the relationship between the number of bendings and the number of broken enameled wires was also examined.

[0031] The shielding layer of the test cable was a cross-woven braid of 12 aggregates and 12 cotton yarns. Each assembly consisted of 11 0.18mmφ tinned annealed copper wires and 0.18mm
It is constructed by bundling one φ enameled wire. That is,
A total of 12 enameled wires are woven into the shielding layer. Here, d / D (d is the outer diameter of the enameled wire, D is the outer diameter of the tin-plated soft copper wire) is 1.

The test results are shown in the graph of FIG. The upward-sloping curve shows the relationship between the number of bendings and the change in resistance of the shielding layer,
The step-shaped line indicates the relationship between the number of times of bending and the number of disconnections of the detection line (enameled line). As shown in the graph, it can be seen that the resistance of the shielding layer increases with an increase in the number of times of bending, and the number of broken tin-plated copper wires increases. Accordingly, the number of broken enameled wires has also increased. As described above, since the increase in the number of broken tin-plated annealed copper wires and the increase in the number of broken enameled wires substantially follow, the life of the cable may be determined based on the predetermined number of broken enameled wires.

[0033]

As described above, according to the cable of the present invention, it is possible to easily detect the disconnection of the metal element wire generated in the shielding layer by checking the continuity of the disconnection detection line. In particular, the disconnection can be detected when the metal element wire is partially disconnected, and the life of the cable can be accurately determined.

When the outer diameter of the disconnection detection wire is d and the outer diameter of the metal wire is D, by setting d / D to 0.5 to 2.0, the detection wire can be formed earlier than the metal wire. Disconnection can be easily performed, and disconnection occurring in the shielding layer can be predicted.

Further, according to the method of the present invention, the disconnection check of the shielding layer can be easily performed. In particular, the disconnection of the shielding layer can be accurately determined even with a simple tester.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration of a cable of the present invention.

FIG. 2 is an explanatory diagram of a disconnection detection method of the present invention.

FIG. 3 is an explanatory diagram of a disconnection detection method of the present invention using a cable conductor as a return line.

FIG. 4 is an explanatory diagram of a disconnection detection method of the present invention using a connector for connecting a resistor.

FIG. 5 is an explanatory view showing a bending test method of a cable.

FIG. 6 is a graph showing a result of a bending test.

FIG. 7A is a schematic plan view showing a braided structure of a shielding layer in a moving cable, and FIG. 7B is a schematic plan view showing a state in which some of the metal wires of the shielding layer are broken. .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Core 2 Shielding layer 3 Sheath 4 Tin-plated soft copper wire 5 Enamel wire 6 Cotton thread 7 Assembly 10,20,30,40
Cable 11 Rotating shaft 12 Weight 15 Fine copper wire 16 Assembly 17
Cotton yarn 21,32,42 Enamel wire 22,33,43 Resistor 23,34,44
One end measurement point 24 The other end measurement point 25,35,45 Tester 31,41 conductor

Continued on the front page (72) Inventor Takashi Tanaka 1-3-1 Shimaya, Konohana-ku, Osaka-shi Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Yasunori Ando 1-Higashi Shinmachi, Higashi-ku, Nagoya Chubu Electric Power Company (72) Inventor Toshiaki Ito 18 Yanagicho, Nagano City Inside Chubu Electric Power Co., Inc. (72) Inventor Tetsu Kadoguchi 3-132, Minato-ku, Nagoya-shi Toenec Co., Ltd. (72) Inventor Masahiro Yamada Kawasaki, Kawasaki City 2-1-1, Sakae Oda-ku, Showa Electric Wire & Cable Co., Ltd. (56) References JP-A-7-29427 (JP, A) JP-A-8-315645 (JP, A) JP-A-59-226420 ( JP, A) JP-A-63-307611 (JP, A) JP-A-10-125141 (JP, A) JP-A-61-224212 (JP, A) Fully open 6-45215 (JP, U) Fully open Sho-51-63986 (JP, U) Sho-sho 63-77219 (JP, U) Sho-sho 56-112820 (JP, U) Sho-sho 61-53824 (JP, U) Sho-sho 63-56521 ( P, U) Akira real public 42-2024 (JP, Y1) (58 ) investigated the field (Int.Cl. ^7, DB name) H01B 7/04 H01B 7/17 H01B 7/32

Claims (3)

(57) [Claims] 1. A moving cable comprising a shielding layer having a braided structure in which an aggregate of metal wires is woven, wherein each of the aggregates has at least one insulating coating.
A moving cable comprising a combination of two disconnection detection lines. 2. The moving device according to claim 1, wherein d / D is 0.5 to 2.0, where d is the outer diameter of the disconnection detection wire and D is the outer diameter of the metal wire. cable. 3. An end of the cable according to claim 1, wherein a resistor having a higher resistance value than the disconnection detection line and having the same resistance value is connected in series to each disconnection detection line.
These resistors are connected in parallel to form a measurement point at one end, and at the other end of the cable, a disconnection detection line is connected in parallel to form a measurement point at the other end. A method for detecting a disconnection of a moving cable, comprising: measuring a resistance value between the two and determining a disconnection number of the disconnection detection line from the resistance value.