JP3363340B2 - Capacitive detection electrode for cable detection device and cable detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an outgoing signal injected into a specific cable from a large number of laying cables by electrostatic coupling at an intermediate portion of the laying route, and based on the detected signal, the laying route. The present invention relates to an electrostatic coupling type detection electrode of a cable detection device and a cable detection method for detecting a specific cable at an intermediate portion of the above.

[0002]

2. Description of the Related Art Hundreds to thousands of cables are laid in power plants, substations, and central control panels of plants.
These cables are connected to relevant electrical equipment throughout the site. Each of these cables has a length of several tens to several hundreds of meters, and at the introduction part to the building or the room or the derivation part from it, the cable is laid through the wall surface or floor surface of the building. To be done. Therefore, it is quite difficult to visually detect a specific cable from a large number of cables in the middle portion of the cable laying route.

When repairing an electric device in the central control panel or in various places in the facility, a specific cable is detected in an arbitrary intermediate portion other than the control room, and the cable is cut or re-operated according to the repair contents of the electric device. The need for connections often arises. Therefore, as this type of cable detection device, one using an electrostatic coupling type detection electrode is known. In the electrostatic coupling type cable detection device, a sine wave voltage is applied from a transmitter between the outermost conductor (core wire when it does not exist) of one end of one cable and the ground, and the other end of the conductor is applied. Shall be insulated (float) from the ground. As a result, the electric field generated around the cable is measured by the receiver from above the outermost insulating layer of the cable via the detection electrode, and as a result, the measurement value with a significant difference from other cables is obtained. The identified cable as a cable for detection purposes. This type of detecting device is disclosed in, for example, Japanese Patent Laid-Open No. 7-2704.
No. 69 publication is known.

[0004]

In the cable detecting device using the electrostatically-coupled detection electrode, the area of the detection electrode is increased, and the detection electrode is placed as close as possible to the surface of the cable so as to face the cable. When the electric coupling rate is increased, a larger detection output can be obtained, and more reliable cable detection can be performed. However, if the detection work is performed for one cable, the electrode can be brought into contact with the cable surface, but there is a limit to increase the electrode area. In order to improve work efficiency, it is possible to bundle dozens of cables and regard them as one cable to proceed with the detection work. In that case, if the outer diameter of one cable is set to 20 mm, the cable in the central portion will be far away from the surface of the bundle by 50 mm or more, and the electrostatic coupling efficiency will be reduced.

Further, when performing this type of cable detection, it is often difficult to secure a sufficient working space especially on the cable side. Therefore, it is not desirable to make the outer shape of the detection electrode too large.

Therefore, as shown in FIGS. 4 and 5, several tens of laying cables 12 are arranged on the outer peripheral surface of the cylindrical cable arranging pipe 10 so as to run parallel to the axis of the cable arranging pipe. The detection electrode 14 is arranged so as to surround the laying cable 12 from the outer peripheral side thereof. The detection electrode 14 is
As shown in FIG. 5, a flexible insulating layer 16, a sheet-like signal electrode 18 attached to the inner surface side thereof, and a sheet-like grounding shield attached to the outer peripheral surface side of the insulating layer 16. Electrode 2
It has 0 and. Signal electrode 18 and shield electrode 2
Insulating layer sheets 22 and 24 are attached on the sheet 0, respectively. A signal detection lead 26 is derived from the signal electrode 18 and is connected, for example, to a preamplifier 28 normally included in the probe. The grounding shield electrode 20 is grounded via the grounding lead wire 30. The output of the preamplifier 28 is led to a receiver body (not shown) for signal processing for cable identification. The insulating sheet 2 is shown in FIG.
2, 24 are not shown.

The detection electrode 14 is used at a cable laying site every time a request for cable detection is made. Therefore, in order to facilitate the assembly and removal of the detection electrode 14, in the unfolded detection electrode shown in FIG. 5, a surface fastener (product name “Magic Tape” that cooperates with each other on the outer surface side at one end and the inner surface side at the other end, respectively. 32) and 34 are attached.

Since the electrostatic coupling type detection electrode shown in FIGS. 4 and 5 outlined above arranges the cable 12 to be detected on the cable arrangement pipe 10 having a relatively large diameter, the cable is arranged at the site where the cable to be detected is laid. It is necessary to ensure sufficient space for arranging the tube 10. If such a space cannot be secured, the detection electrode 14 cannot be attached, so that the cable detection itself becomes impossible.

Therefore, it is an object of the present invention to provide an electrostatically coupled detection electrode and a cable detecting method capable of performing good cable detection even in a relatively narrow space.

[0010]

In order to solve the above problems, the present invention detects a transmission signal injected into a specific cable from a large number of installed cables by electrostatic coupling at an intermediate portion of the installed route. , In the electrostatic detection electrode of a cable detection device that detects a specific cable in the middle part of the laying route based on the detection signal, a large number of laying cables are wound around a few cables as a unit. A wire-shaped electric wire having a signal detection lead wire for external lead-out, a flexible insulating layer surrounding a large number of laying cables around which the signal electrodes are wound, and an outer peripheral surface side of the insulating layer. A sheet-shaped shield electrode is provided.

Further, according to the present invention, a signal electrode composed of a string-shaped electric wire is wound around a number of laying cables in units of several cables, and an insulating layer is further provided on the laying cables wound with the signal electrodes. A shield electrode in the form of a sheet is wound around, a transmission signal is injected from one end of the cable between a specific cable and the shield electrode among many laying cables, and the injected transmission signal is signal electrode at the middle part of the laying route. It is characterized in that it is detected by electrostatic coupling via the cable, and a specific cable is detected in the middle portion of the laying route based on the detection signal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows one embodiment of the present invention. A plurality of laying cables 12, for example, 3 to 4 laying cables are used as a unit, and the signal electrode 8 formed of a string-shaped electric wire as shown in FIG. The winding unit in this case is determined with the intention that the signal electrode 8 contacts all of the cables 12 to be detected. Next, the ground electrode 6 as shown in FIG. 3 is wound with the insulating layer 16 inside so as to surround the laying cable 12 around which the signal electrode 8 is wound.

As shown in FIG. 3, the ground electrode 6 includes a flexible sheet-like insulating layer 16 made of foamed polyethylene or the like,
Sheet-shaped grounding shield electrode 20 adhered thereon
It has and. The shield electrode 20 can be composed of a copper tape or a knitted ultrafine copper wire. An insulating sheet 24 made of polyethylene, for example, is attached as an insulating layer on the shield electrode 20. It is preferable that the capacitance between the signal electrode 8 and the shield electrode 20 in FIG. 1 is small. Therefore, in order to increase the clearance between the electrodes 8 and 20, the insulating layer 16 is made of foamed polyethylene and has an appropriate thickness and an appropriate amount. It is preferable that an air layer is formed. A signal terminal 8a is attached to one end of the string-shaped signal electrode 8, and the signal detection lead wire 2 is connected to the signal terminal 8a.
6 is derived, which is connected, for example, to a preamplifier 28 normally included in the probe. The grounding shield electrode 20 is grounded via the grounding lead wire 30. Preamplifier 2
The output of 8 is led to a receiver body (not shown) for signal processing for cable identification. The insulating sheet 24 is not shown in FIG. 1.

When detecting a cable, the cable 12 to be detected is opened, the above-mentioned signal electrode 8 and ground electrode 6 are attached to the detection point, and one end of the cable 12 to be detected is connected to the core wire or the outermost layer conductor. A transmission signal is injected into the ground, and a signal induced between the signal electrode 8 and the ground at the detection point is detected through the preamplifier 28 and guided to a signal processing circuit (not shown) for the purpose of detection. Identify the cable.

The signal electrode 8 is connected via a lead wire 26 to a preamplifier 28 having a large input impedance in order to make the lead wire wiring distance from the signal electrode 8 and the ground electrode 6 to the receiver main body long. Good to do. Therefore, the preamplifier 28 has a large input impedance F
It is preferable to use an ET (field effect transistor). As a result, the output impedance of the preamplifier 28 is reduced and a long lead wire can be drawn.

The signal electrode 8 and the ground electrode 6 are used at a cable laying site every time a cable detection request is made. Therefore, it is desirable that the ground electrode 6 has a structure that is easy to assemble and remove. Therefore, in the unfolded ground electrode 6 shown in FIG. 3, surface fasteners (trade name “magic tape”) 32, 34 that cooperate with each other at one end on the front surface side (outer surface side) and the other end on the back surface side (inner surface side), respectively. It is convenient to install the. The ground electrode 6 in a developed state is wound around the many laying cables 12 around which the string-shaped signal electrodes 8 are wound, and tightened using the surface fasteners 32 and 34.
The detection electrode 14 in the state shown in FIG. 1 is constructed. After the cable detection work is completed, the hook-and-loop fasteners 32 and 34 can be disengaged and easily removed.

[0017]

According to the present invention, the electrostatic coupling type detection electrode is suitable for advancing the cable detection work for a large number of cables to be detected at one time and can be attached to a place where only a relatively narrow working space can be secured. And a cable detection method can be provided.

[Brief description of drawings]

FIG. 1 is a view of an electrostatically coupled detection electrode according to the present invention viewed from an end face side of a cable.

FIG. 2 is a diagram showing a string-shaped signal electrode used for the detection electrode of FIG.

3 is an exploded perspective view of the ground electrode of FIG.

FIG. 4 is a view of a conventional electrostatic coupling type detection electrode according to the prior art of the present invention as seen from the end face side of a cable.

5 is an exploded perspective view of the detection electrode of FIG.

[Explanation of symbols]

6 ground electrode 8 String-shaped signal electrodes 12 laying cable 14 Detection electrode 16 Flexible insulating layer 20 Shield electrode 24 Insulation sheet 26 Signal detection lead wire 28 Preamplifier 30 Grounding lead wire 32,34 hook-and-loop fastener

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-318691 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01R 31/02

Claims (3)

(57) [Claims] 1. A transmission signal injected into a specific cable from a large number of laying cables is detected by electrostatic coupling in an intermediate portion of the laying route, and a specific signal is detected in the intermediate portion of the laying route based on the detected signal. In the electrostatic coupling type detection electrode of the cable detection device for detecting a cable, the many laying cables are composed of a string-shaped electric wire sequentially wound by several cables as a unit, and an external lead-out signal detection lead wire is provided. A cable including a signal electrode having, a flexible insulating layer surrounding the many laying cables around which the signal electrode is wound, and a sheet-shaped shield electrode attached to the outer peripheral surface side of the insulating layer. Capacitive detection electrodes for detectors. 2. The electrostatically coupled detection electrode according to claim 1, wherein an insulating sheet is attached on the shield electrode. 3. A plurality of laying cables are sequentially wound with a signal electrode consisting of a string-shaped electric wire in the unit of several cables, and further, a plurality of laying cables wound with the signal electrodes are provided with an insulating layer interposed therebetween. Winding a sheet-shaped shield electrode, injecting a transmission signal from one end of the cable between the specific cable and the shield electrode in the plurality of laying cables, and the injected transmission signal at the intermediate portion of the laying route A cable detection method characterized by detecting electrostatically through an electrode and detecting a specific cable at an intermediate portion of a laying route based on the detection signal.