JPH099439A - Cable recognition device and current sensor that can be used of the device - Google Patents

Abstract

PURPOSE: To make it possible to distinguish one specified cable easily from a plurality of cables collectively installed by recognizing the specified cable based on the correlation between the signal current detected by a current sensor and specified signal current. CONSTITUTION: A cable 1 is completely surrounded by a ring-shaped iron core 3A of a clamp sensor 3. Magnetic flux caused by the current running in a core wire 1A of the cable 1 is converted into current by means of a winding 3B of the clamp sensor 3 and thereby the current running in the cable 1 is detected. Based on the correlation between the thus detected current running in the cable 1 and the current (10mA, 982.5Hz) supplied through a signal line 2, it is checked if the cable is the one that is expected to be found. The clamp sensor 3 detects the magnetic flux and a magnetic field which are caused by the current running in the core wire 1A of the cable 1, by means of a divided current transformer with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable identification device and a current sensor that can be used for the cable identification device, and more particularly to a cable identification device that detects a target cable at low cost and with high accuracy and a current sensor that can be used for the cable identification device.

[0002]

2. Description of the Related Art In recent years, cables through which various signals such as control signals, data signals and power signals flow are buried in the ground,
Alternatively, many cables are often laid together in a pipeline installed underground or on the ground. It is easy to bundle and lay such a large number of cables, but when only one of the cables is unnecessary, it is desired to remove and remove the one cable. in this case,
Since both ends of the cable are connection sides of the device, it is easy to identify, but unless the total length is short, the cable is usually long and it is difficult to identify the cable to be removed in the middle part. is there.

[0003] Conventionally, when removing one cable from a large number of cables buried in the ground, the middle part of the cable which moves up together with one end of the cable is visually confirmed. Determine that it is the cable, and lift up the middle part of the cable,
After that, likewise, lift the middle part of the cable in sequence,
The entire cable is identified when it finally reaches the other end of the cable.

However, in this method, when one cable among a large number of cables that are laid all together is lifted, in response to this, in addition to the target cable, it is arranged in the vicinity thereof. It is difficult to identify which cable is the target cable because the middle part of the existing cable is also lifted, and it takes time to confirm and identify it, and other cables that are operating normally due to incorrect recognition. There is also a risk of lifting or sometimes disconnecting. Therefore, there is a problem that workability is reduced particularly in the case of a long cable.

As a method for more reliably identifying a specific cable including such a midway portion, a method of detecting an induced current signal generated from a current flowing through the cable by using a current sensor is used. This method is shown in FIG.
As shown in FIG. 1, at one end side of the cable 10, the core wires 10A, 10B, 10 arranged inside the cable 10 are provided.
A signal power source (constant current source, constant voltage source, etc.) 20 is connected between the two core wires 10A and 10B of C, ... 10B is connected by a jumper wire 11. And the core wires 10A and 10B
The current flowing through the cable is detected from the outside of the cable 10 by the sensor 30 to identify the target cable. The sensor 30 is an electromagnetic sensor 30A that converts a magnetic field into an electric current.
And a signal detector 30B for detecting the current obtained by the electromagnetic sensor 30A, and when the predetermined signal is detected, the cable is identified as the target cable. Connect the sensor 30 to the midway position of the cable L1, ..., L2, ...
・ By moving to, the target cable at each position can be identified as well.

[0006]

As described above, as described above,
In order to electrically identify the target cable, a current is supplied to the core wire of the cable, the sensor 3 is placed close to the outside of the cave, and the current due to electromagnetic induction is detected. To identify the target cable.

However, since many cables are often concentrated and laid close to each other, when a regular current is flowing through a cable other than the target cable,
The sensor may detect an induced current from another cable, resulting in erroneous recognition. Especially, as described above, various kinds of signal currents flow in the cable, and some of them carry large currents, which increases the risk of erroneous recognition and poses a problem in terms of reliability. is there.

Therefore, an object of the present invention is to provide a cable identifying device which can easily identify a specific one cable from a plurality of cables arranged in a concentrated manner, and a current sensor which can be used for the cable identifying device. is there.

[0009]

In order to solve the above problems, the cable identifying apparatus of the present invention grounds one end of a conductor provided on one specific cable among a plurality of cables, and A predetermined signal current is supplied from the other end of the cable to surround a predetermined one of the plurality of cables inside the annular magnetic path at a position arranged at a predetermined distance from the other end. A current sensor is provided, and the predetermined cable is distinguished from the specific cable based on the correlation between the signal current detected by the current sensor and the predetermined signal current. Here, the predetermined signal current is a burst signal having a predetermined current value and a predetermined period and a predetermined frequency and time width,
The predetermined current value is 10 mA, the predetermined frequency is 982.5 HZ, and the predetermined time width is 0.
It is preferable that the predetermined period is 5 seconds and the predetermined period is 1 second.

Further, at least a part of the current sensor is detachable, and an annular iron core, a winding wound around the iron core, and a current flowing through the winding are amplified by a predetermined gain and detected. It has current detection means and gain control means for increasing the predetermined gain in the separated state and returning it to the original gain in the contact state.

[0011]

[Operation] In the present invention, in order to determine one specific cable among a plurality of cables collectively arranged in the ground, one end of one cable is grounded from the other end of a conductor. A signal current is supplied, and based on the correlation between the signal current detected by the current sensor arranged so as to surround the cable inside the annular magnetic path at a predetermined position along the cable and the predetermined signal current. Then, for example, when the magnitude of the current, the frequency, and the like match, it is distinguished from the specific cable.

[0012]

EXAMPLES Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a cable identification device of the present invention.

In FIG. 1, at one end of the cable 1, one of the core wires 1A, 1B, 1C, ... Of the cable 1 is connected to a signal power source 2 to supply a specific current, The core wire 1A on the other end side of the cable 1 is grounded. The electric current supplied from the signal power source 2 may be supplied to the sheath (conductive blocking layer 1) and the ground circuit other than the core wire.

In the present embodiment, the clamp sensor 3 detects the current flowing inside the cable 1, and based on the correlation between the detected current and the current supplied from the signal source 2, whether or not the cable is the target cable is determined. recognize.

The clamp sensor 3 is a split-type current transformer for measuring leakage current, and detects the magnetic flux and magnetic field generated by the current flowing through the core wire 1A of the cable 1 with high accuracy. Since the clamp sensor 3 is magnetically shielded, it is insensitive to an external magnetic field (induced current), that is, it is insensitive to only the current flowing through the measurement target (target cable).
This is because the shield is made insensitive to the external magnetic field (induced current), so that the magnetic flux (current) can be detected with high accuracy (within error of ± 1%).

As shown in FIG. 2, the clamp sensor 3 has a winding 3B wound around a circular annular iron core 3A,
A signal detector 3C is connected to the winding 3B. The circular annular core 3A of the clamp sensor 3 can be divided and separated, and when used, as shown in FIG.
A is divided and separated to form a gap S.
After inserting the target cable candidate from the above and arranging it in the vicinity of the central portion in the annular core portion 3A, the dividing and separating portions are brought into close contact with each other to form a circular magnetic path having a small magnetic resistance. In this state, as shown in the figure, the cable 1 is completely surrounded in the annular core portion 3A of the clamp sensor 3, and the magnetic flux generated by the current flowing through the core wire 1A of the cable 1 causes the winding 3B of the clamp sensor 3 to rotate. Is converted into a current, and eventually the current flowing in the cable is detected.
This current is measured by the signal detector 3C, and based on the relative relationship between the measured current and the current supplied from the signal power source 2, it can be determined whether or not the cable to be measured is the target cable. .

The relative relationship between the current from the signal power source 2 and the current detected by the clamp sensor 3 is defined as the sameness such as magnitude of both currents and the sameness including phase and frequency relations. can do. Here, if both currents are substantially equal, it can be determined that the target cable is inserted in the clamp sensor 3.

At this time, if only the magnitude of the current is used as a criterion for judgment, when a large current such as a power signal flows through a cable arranged in the vicinity, the clamp is performed due to the leakage current when the above-mentioned shield effect is not sufficient. The sensor 3 may malfunction. In addition, a long cable may malfunction due to a decrease in current due to leakage of current due to stray capacitance between the cable of the distributed constant circuit of the cable and the ground.

Therefore, in another embodiment of the present invention, the current supplied from the signal power source 2 is set to an intermittent burst signal as shown in FIG. 3, the frequency thereof is set to 982.5 Hz, and the burst signal pulse is set. The width of the signal is set to 0.5 seconds, and the time until the next burst signal is set to 0.5 seconds. Then, when the specific format signal current is detected by the clamp sensor 3, it is determined that the cable is the target cable. Set the burst signal frequency to 9
The reason why 82.5 Hz is set is to prevent interference with the detection signal due to the high frequency component of the power supply signal flowing through other cables because the frequencies of the applicable power supply in Japan are 50 Hz and 60 Hz. Of the 20th high frequency component and the 16th high frequency component of 60 Hz. Further, the current value of 10 mA is set as the minimum detectable value that can be distinguished from the influence from the outside (external noise).

In this embodiment, the clamp sensor 3 is configured as described above and the clamp sensor 3 is set to a predetermined distance L from one end of the cable 1.
1 to identify a target cable, cut a portion from the one end side of the identified cable to a predetermined distance position, and similarly to the core wire 1A of the cable 1 remaining after the cutting, the signal power source 2
, And clamp sensor 3 at position L2 further away
The target cable is identified by arranging the cables, and after the identification, the cable is separated in the same manner, and this process is sequentially repeated.
By repeating the measurement and identification up to the other end of the cable, the entire target cable can be removed.

Incidentally, without disconnecting the cable,
Of course, the entire target cable may be identified by moving the clamp sensor 3 in the length direction of the cable.

By the way, it is difficult to quickly predict one target cable from a large number of laid cables, and it is a quick measurement to measure a plurality of cables including the target cable as one group target. , Is necessary for identification. In this case, with the circular annular core 3A of the clamp sensor 3 divided and separated, it is possible to approach the predetermined cables of the above-mentioned many cables and perform a rough search by the measured current. In this state, the magnetic resistance of the void portion becomes large, so that the detection ability deteriorates, and it becomes difficult to detect a minute current. Therefore, in this embodiment, when the above-mentioned division / separation state is detected, the detection capability is maintained by increasing the gain of the detection system.
When the split / separated state is lost, the gain is returned to the original gain.

[0023]

As described above, according to the cable identifying apparatus of the present invention, a specific one cable can be easily identified from a plurality of cables concentratedly arranged in the ground or the like, and the efficiency can be improved. It is possible to carry out specific construction.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a cable identification device according to the present invention.

FIG. 2 is a diagram showing a configuration example of a clamp sensor 3 as a current sensor in FIG.

FIG. 3 is a diagram showing an example in which a current supplied from a signal power supply 2 in the embodiment of FIG. 1 is an intermittent burst signal.

FIG. 4 is a schematic configuration diagram of a conventional cable identification device.

[Explanation of symbols]

 1,10 Cable 1A to 1C, 10A to 10C Core wire 2,20 Signal source 3 Clamp sensor 3A Iron core 3B Winding 3C Signal detector 30 Sensor 30A Electromagnetic sensor 30B Signal detector

Claims (4)

[Claims] 1. A conductor provided on one specific cable of a plurality of cables is grounded at one end, a predetermined signal current is supplied from the other end of the conductor, and the conductor is distributed at a predetermined distance from the other end. A current sensor is arranged so as to surround a predetermined one of the plurality of cables inside the annular magnetic path at the position where the signal is detected by the current sensor and the predetermined signal. A cable identifying device for identifying the predetermined cable from the specific cable based on a correlation with an electric current. 2. The cable identifying device according to claim 1, wherein the predetermined signal current is a burst signal having a predetermined current value, a predetermined cycle, and a predetermined frequency and time width. 3. The predetermined current value is 10 mA, the predetermined frequency is 982.5 HZ, the predetermined time width is 0.5 seconds, and the predetermined cycle is 1 second. The cable identification device described in 1. 4. An annular iron core, a winding wound around the iron core, at least a part of which is detachable, and a current detecting means for amplifying and detecting a current flowing through the winding with a predetermined gain. A current sensor, comprising: a gain control means for increasing the predetermined gain in the separated state and returning the gain to the original gain in the contact state.