JPH11337606A - Cable detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency in detection of a specific cable. SOLUTION: At detecting of specific cables 4a-4c, sinusoidal wave currents having different frequencies are made to flow into the cores 5 or shielding wires 6 of the cables 4a-4c. The current values of the sinusoidal wave currents are fixed, regardless of the impedance differences among the cables 4a-4c. Then the magnetic fields generated around the cables 4a-4c are measured by means of search coil devices 2 and 2 which are provided with bar-antenna type search coils 10 and clamping type search coils 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The cable detecting apparatus according to the present invention is used, for example, when changing wiring at a power plant, a substation, or various factories (hereinafter referred to as "power plants"). , A control cable, a power cable, and the like, to find a specific cable from a large number of cables.

[0002]

2. Description of the Related Art Hundreds or thousands of cables are laid in a central control panel provided in a control room of a power plant or the like. One end of each of these cables is connected to the central control panel. I have. Each of these cables has a length of several tens of meters to several hundreds of meters, and is used for a building provided with the central control panel or a machine provided with a mechanical device to which the other end of each cable is connected. It is laid so as to penetrate the wall and floor. For this reason, it is difficult to specify an intermediate portion of some of the cables in the control room or outside the building. On the other hand, in the case of renovation work at power plants,
It becomes necessary to cut and reconnect any of the cables in the middle.

For this reason, conventionally, a detection current is fed to a core wire or a shielded wire of a cable to be detected, and a magnetic field or an electric field generated around the cable to be detected due to the feeding of the detection current is searched for. 2. Description of the Related Art There is known a cable detecting device that detects a specific cable by detecting the cable. Conventionally, such a cable detecting device has been disclosed in Japanese Patent Application Laid-Open Nos.
Nos. 22424, 6-230057 and 6
-235747, 7-270469, 9-281175, 9-318691,
The thing described in the 9-322347 gazette etc. is known. Conventionally known cable detection devices described in these publications include an electromagnetic induction type and an electrostatic coupling type. The electrostatic coupling type includes a pulse application type and a sine wave application type. In summary, there are three types of known cable detecting devices.

In the cable detection device of this type, a sine-wave current flows through a conductor such as a core wire or a shield wire constituting a specific cable to be detected. For this purpose, a sine wave voltage is applied between one end of the conductor and the ground, and the other end of the conductor is connected (grounded) to the ground. Alternatively, the above-mentioned sine wave voltage is applied between one ends of two conductors constituting two cables whose both ends are disposed close to each other, and the other ends of the conductors constituting these two cables are connected. . It is to be noted that detecting an end of a conductor constituting a specific cable can be easily performed, unlike detecting an intermediate portion. When a sine wave current is applied to a conductor such as a core wire or a shielded wire of a cable to be specified as described above, a magnetic field is generated around the cable, and the magnetic field is measured by a detector. That is, the presence or absence and strength of the magnetic field are measured by a detector having a coiled antenna for each of a plurality of cables including the cable to be specified, and there is a significant difference from other cables (around Cable whose magnetic field is clearly stronger than other cables) is the cable to be specified.

Device for detecting a sine wave applying type electrostatic coupling type cable In this type of cable detection device, a sine wave is applied between one end of a shielded wire (outermost layer conductor) constituting a specific cable to be detected and the ground. A wave voltage is applied, and the other end of the shield wire is insulated from the ground (open without grounding). When a sine wave voltage is applied between the shielded wire and the ground in this way, an electric field is generated around the specific cable, so that the electric field is measured by a detector in the same manner as in the above case, and Find cables to identify.

[0006] Detecting device of pulse application type electrostatic coupling type cable [0006] In this type of cable detecting device, a cable between one end of a shielded wire constituting a specific cable to be detected and the ground.
A coded pulse voltage is applied, and the other end of the shield wire is insulated from the ground. By applying a pulse voltage between the shielded wire and the ground in this way, the electric field generated around the specific cable is measured by a detector in the same manner as described above, and a code is obtained from the measured value. reading,
The cable to be identified is detected. The basic principle of detecting a specific cable by the pulse application type electrostatic coupling type cable detection device is the same as that of the sine wave application type. Especially,
In the case of the pulse application type, by changing the code of the pulse voltage applied to the shield wires of multiple cables,
It is possible to detect a plurality of cables at a time, thereby improving the efficiency of the detection work.

The most preferable for detecting a specific cable from a large number of cables is a pulse application type electrostatic coupling type in terms of efficiency and energy consumption during the detection operation. However, when using an electrostatic coupling type cable detection device including a pulse application type and a sine wave application type, one end of the shielded wire of the cable to be specified can be detected and the other end of this shielded wire must be grounded. It must be able to insulate it. However, the shielded wire may be grounded below the central control panel, such as below the floor of a control room, in a state where the shielded wires of a plurality of cables are put together.
In such a case, one end of the shielded cable of the cable to be specified cannot be detected in the control room. In addition, the other end of the shielded wire may be grounded under the floor of a building provided with a mechanical device or the like.In such a case, the other end of the shielded wire of the cable to be specified is insulated from the ground. (Opening) is difficult.

As described above, when one end of the shielded wire of the cable to be specified cannot be detected or the other end of the shielded wire cannot be insulated from the ground, the pulse application type and the sine wave application type are included. The detection device for the electrostatic coupling type cable cannot be used, and the detection device for the electromagnetic induction type cable must be used. Further, even if one end of the shielded wire of the cable to be specified can be detected and the other end of the shielded wire can be insulated from the ground, the frequency of the sine wave current flowing through the core wire constituting each cable including the cable to be specified can be detected. In the case where the amplifier is saturated, the detection device for the electrostatic coupling type cable cannot be used, and the detection device for the electromagnetic induction type cable must be used. FIG. 5 shows a procedure for determining when it is necessary to use the electromagnetic induction cable detection device.

[0009]

In order to reliably detect a specific cable using an electromagnetic induction type cable detecting device, a sine wave current is applied to the core wire or shield wire of the cable to be specified. In this case, it is necessary to clarify the magnetic field generated around the cable and to efficiently detect the magnetic field. For this reason, conventionally, it has been considered that the frequency of the sine wave current flowing through the core wire or the shield wire can be freely converted.

However, in the case of the conventional electromagnetic induction type cable detecting apparatus, the above-mentioned sinusoidal current is supplied at a constant voltage regardless of the difference in impedance of the cable to be specified. You may not be able to do the work. For example, if the frequency of the sine wave current is 3.5 kHz and the measurement can be performed with a current of about 2 A, if the frequency is changed to 9.5 kHz, no current will flow due to an increase in impedance. In some cases, the above measurement operation cannot be performed. Even when the measurement work can be performed, if the cable to be specified changes and the impedance changes, the current value of the sine wave current changes and the strength of the magnetic field or electric field changes. You have to adjust the sensitivity of the receiver to do so. It is difficult to adjust the sensitivity of the receiver in a state where the cable to be identified cannot be distinguished from other cables,
Significantly hinders the efficiency of cable detection work. The cable detecting device of the present invention has been invented in view of such circumstances.

[0011]

The cable detecting device of the present invention is used for detecting a specific cable at an intermediate portion of a laying route from a plurality of laying cables. Such a cable detecting device according to the present invention includes a transmitter for feeding a detection current to a conductor such as a core wire or a shielded wire of a cable to be detected, and the above-described detection device for sending the detection current in accordance with the feeding of the detection current. A search coil device for detecting a magnetic field generated around the cable is provided, and a receiver for inputting and processing a signal representing the magnetic field detected by the search coil device is provided. The transmitter is capable of transmitting detection currents of a plurality of types of frequencies having a relationship of a non-integer multiple to each other, and keeps the value of the detection current flowing through this cable constant regardless of the impedance difference of the cable to be detected. It is provided with a constant current control function for keeping the current. Further, the search coil device includes a bar antenna type search coil capable of detecting the magnetic field with respect to a plurality of cables, and a clamp type search coil capable of detecting the magnetic field with respect to only one cable.

[0012]

According to the cable detecting device of the present invention constructed as described above, a sinusoidal current is caused to flow through the core wire or the shield wire of the specific cable to be detected for the following reasons. Work can be performed efficiently. First, since the value of the detection current flowing through the cable is kept constant, the intensity of the magnetic field existing around the specific cable can be made substantially constant regardless of the difference in the impedance of the specific cable. Therefore, the operation of adjusting the sensitivity on the receiver side becomes unnecessary, and the trouble of adjusting the sensitivity of the receiver in a state where the cable to be specified cannot be distinguished from other cables is eliminated.

Secondly, since a bar antenna type search coil and a clamp type search coil are provided, a plurality of cables including the above-mentioned specific cable are sieved from a large number of cables, and then the plurality of cables are sieved. The work of detecting the above-mentioned specific cable can be performed from the inside. For this reason, the number of times of measurement of the magnetic field existing around the above-mentioned many cables is reduced as compared with a case where one magnetic field is measured for each of many cables, and the work of detecting the above-mentioned specific cable is made more efficient. Can be achieved. Third, since the transmitter can transmit detection currents of multiple types of frequencies that are non-integer multiples of each other, it is possible to simultaneously detect multiple specific cables using multiple sets of detection devices Thus, when there are a plurality of specific cables to be detected, the efficiency of the detection operation can be improved.

[0014]

1 to 4 show an example of an embodiment of the present invention. The cable detection device according to the present invention includes:
As shown in FIG. 1, a transmitter 1, a search coil device 2,
And a receiver 3. FIG. 1 shows three sets of such cable detecting devices, and three cables 4a, 4b, 4
This figure shows the case where the detection of c can be performed.
The transmitter 1 among them is a cable 4a, 4
A detection current is sent to the core wire 5 or the shield wire 6 of b, 4c. In the illustrated example, in order to detect the above-mentioned electromagnetic induction type cable using the core wire 5 with respect to the uppermost cable 4a, at one end of the core wire 5 of the cable 4a,
A detection current is sent. On the other hand, regarding the middle cables 4b and 4c, the shielded wires 6 and 6c of the cables 4b and 4c are used to detect the electromagnetic induction type cables by using the shielded wires 6.
The detection current is sent to one end of each. Therefore, in the illustrated example, the uppermost cable 4a
The other end of the core wire 5 and the other ends of the middle cables 4b and 4c are grounded. The remaining cables 4d, 4d are
It is outside the scope of detection.

Each of the transmitters 1 is configured as shown in the block diagram of FIG. 2 so as to be able to transmit detection currents of a plurality of types of frequencies having a non-integer multiple relationship with each other.
In the illustrated example, the frequency of this detection current is 3.5 kHz.
And 6.0kHz and 9.5kHz. As described above, the reason why the frequencies of the detection currents are non-integer multiples is that when the three sets of cable detection devices are used at the same time, if the operating frequencies of these detection devices are made different from each other, the detection is performed mutually. This is for preventing interference between the currents for use.

The transmitter 1 as shown in FIG.
When the detection current is sent to the core wire 5 or the shield wire 6 of the terminals a, 4b, and 4c, the detection current is supplied to the terminals 7a,
7b. In other words, the core wire 5 or the shield wire 6 exists between these terminals 7a and 7b. Thus, the value of the current flowing between the terminals 7a and 7b is detected via the detection transformer 8. Then, irrespective of the difference in impedance between the cables 4a, 4b, and 4c to be detected, constant current control is performed to keep the value of the detection current flowing through each of the cables 4a, 4b, and 4c constant. This constant current control is performed by changing the voltage applied between the terminals 7a and 7b based on the detection signal of the detection transformer 8.

When detecting the cables 4a, 4b and 4c, the value of the detection current flowing through the core wire 5 or the shield wire 6 is as follows:
The current can be adjusted steplessly by the current setter 9, but the maximum value of the detection current is about 2A. Further, when the impedance of the cables 4a, 4b, 4c to be detected is large, the value of the voltage applied between the terminals 7a, 7b becomes large, but even in such a case, the voltage is controlled so as not to exceed 30V. To protect each component. Also, a core wire 5 or a shield wire 6 through which the detection current is to flow from one end.
Is in a no-load state (a state in which the other end is open), the transmitter 1 stops outputting. Further, while the transmitter 1 is in the operating state, the cable 4 to be detected is
a, 4b, and 4c, these cables 4a,
4b, 4c, in order to prevent an excessive stamp current from flowing,
A stamp current suppression circuit for circulating the stamp current in the transmitter 1 is provided.

Each of the search coil devices 2, 2 is for detecting a magnetic field generated around the cables 4a, 4b, 4c to be detected in response to the supply of the detection current. Each of such search coil devices 2 and 2 includes a bar antenna type search coil 10 and a clamp type search coil 11 as shown in FIG. These search coils 10 and 11 are connected via a switching means such as a changeover switch or a changeover plug so that a detection signal of either one of the search coils 10 (or 11) can be input to the receivers 3 and 3 freely. , Are connected to these receivers 3, 3, respectively.
The bar antenna type search coil 10 of the bar antenna type search coil 10 and the clamp type search coil 11 is capable of detecting magnetic fields generated around the cables 4a, 4b, 4c with respect to a plurality of cables ( (The range that can be detected is wide.) On the other hand, the clamp-type search coil 11 can detect the magnetic field only with respect to one cable (the detection range is narrow), and allows one cable to be inserted inside. When performing a magnetic field measurement using such a clamp-type search coil 11,
After the cable to be measured is inserted into the coil unit 12 with the coil unit 12 being opened, the coil unit 12 is closed. For the measurement of the magnetic field, this coil part 12 was
Perform in a closed state as shown in FIG.

Further, the receiver 3 inputs and processes a signal representing a magnetic field detected by the bar antenna type search coil 10 or the clamp type search coil 11 constituting the search coil device 2. As shown in FIG. 4, such a receiver 3 has a frequency of less than 1 kHz including a sine wave current frequency of a commercial power supply flowing through the core wire 5 of the cables 4a to 4d, and
and a band-pass filter 13 for cutting frequencies exceeding 1 kHz and passing only a frequency signal of about 1 to 20 kHz, and a narrow frequency band centering on the three frequencies of 3.5 kHz, 6.0 kHz and 9.5 kHz. Narrow bandpass filters 14 and 14 that pass only signals, and filters 13 and 14
And a level indicator 16 for displaying the level of the signal detected by the search coil device 2.

When a specific cable is to be detected by the cable detecting device of the present invention having the above-described configuration, the specific cables 4a to 4c to be detected by the transmitters 1 and 3.5 are set to 3.5 kHz. And a sinusoidal current of any one of three frequencies of 6.0 kHz and 9.5 kHz flows. Then, the magnetic field generated around the cables 4a to 4c is measured by the bar antenna type search coil 10 or the clamp type search coil 11 constituting each of the search coil devices 2, 2. Each of the receivers 3 receiving the detection signal from each of the search coil devices 2, 2,
The specific cables 4a to 4c are detected by observing the detection values displayed on the level indicator 16 of No.3.

In particular, according to the cable detecting device of the present invention, each of the transmitters 1 is connected to each of the specific cables 4a to 4a.
In order to keep the value of the detection current flowing in the specific cables 4a to 4c constant, the intensity of the magnetic field existing around each of the specific cables 4a to 4c is substantially constant irrespective of the impedance difference between the specific cables 4a to 4c. it can. Therefore, the operation of adjusting the sensitivity of each of the receivers 3 and 3 becomes unnecessary, and each of the receivers 3 and 3 cannot be distinguished from the cables 4a to 4c to be specified and the other cables 4d and 4d. Eliminates the hassle of adjusting sensitivity. That is, if the detected value displayed on the level display 16 is a certain value,
It is not necessary to adjust the sensitivity in a state where it is not known whether the magnetic field of ~ 4c is captured. Therefore, the specific cable 4a
4c can be easily and reliably determined.

Further, since each of the search coil devices 2 and 2 is composed of a bar antenna type search coil 10 and a clamp type search coil 11, each of the above-mentioned specific cables is selected from among a large number of cables 4a to 4d. Cables 4a-4c
After sieving a plurality of cables including the specific cables 4a to 4c from among the plurality of cables.
Can perform the task of detecting. For this reason, the number of measurements of the magnetic field existing around the large number of cables 4a to 4d is reduced as compared with the case where the magnetic field is measured one by one for each of the multiple cables 4a to 4d. ~ 4c
The efficiency of the work of detecting the information can be improved.

Further, each of the transmitters 1 and 1 has a non-integer multiple relationship with each other, ie, 3.5 kHz, 6.0 kHz and 9.5 kHz.
Since the detection currents of three different frequencies can be transmitted, the frequency of the detection currents can be made different from each other, thereby making it possible to detect up to three specific cables 4a to 4c at the same time. The efficiency of the detection operation when a plurality of specific cables 4a to 4c are present can be improved. still,
The cable detecting device of the present invention can be used for detecting any cable such as a power cable, a control cable, and an instrumentation cable.

[0024]

Since the cable detecting device of the present invention is constructed and operates as described above, it is possible to reliably and easily detect a specific cable and contribute to the efficiency of repair work of a power plant or the like. .

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a cable detection device according to the present invention.
FIG. 4 is a block diagram showing an example.

FIG. 2 is a block diagram of the transmitter.

FIG. 3 is a front view of the search coil device.

FIG. 4 is a block diagram of the receiver.

FIG. 5 is a flowchart showing a procedure for selecting a cable detection method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transmitter 2 Search coil device 3 Receiver 4a, 4b, 4c, 4d Cable 5 Core wire 6 Shield wire 7a, 7b Terminal 8 Detection transformer 9 Current setting device 10 Bar antenna type search coil 11 Clamp type search coil 12 Coil part 13 Band Filter 14 Narrow band filter 15 Amplifier 16 Level indicator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomohiro Imazumi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Masahiro Kuroiwa 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Yuji Takahashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (1)

[Claims] A transmitter for feeding a detection current to a conductor constituting a cable to be detected, and a transmitter for detecting a magnetic field generated around the cable to be detected due to the feeding of the detection current. A search coil device, and a receiver for inputting and processing a signal representing a magnetic field detected by the search coil device, wherein the transmitter transmits detection currents of a plurality of types of frequencies having a non-integer multiple relationship with each other. And a constant current control function for keeping the value of the detection current flowing through the cable constant irrespective of the impedance difference of the cable to be detected. A bar antenna type search coil capable of detecting a magnetic field with respect to a plurality of cables and a clamp type search coil capable of detecting a magnetic field with only one cable are provided. A cable detection device.