JP6544738B2 - Electromagnetic field sensor - Google Patents

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an electromagnetic field sensor for use in a cable locating device that can identify a cable installation path from a distant place and identify a desired cable among a plurality of cables.

  A conventional electromagnetic field sensor is made of a nonmagnetic material having conductivity, is made of a substantially annular electrode that circumferentially surrounds a part of the cable in a clamped state of the cable, and is made of a magnetic material via an insulator. A magnetic core disposed outside the ring of the electrode, a winding around which the magnetic core is wound, and an output part which is drawn out from the electrode by a lead and drawn out from both ends of the winding by a lead; An induced current generated in the winding by induction is output from the output unit, and a voltage generated in the electrode by electrostatic induction is output from the output unit (see, for example, Patent Document 1).

JP, 2011-059070, A

The detection sensitivity of the receiver connected to the conventional electromagnetic field sensor is greatly influenced by the number of magnetic flux interlinking inside the coil of the electromagnetic field sensor, in addition to the performance of the receiver.
That is, in the conventional electromagnetic field sensor, when the cable is clamped, an annular coil is formed, and the number of magnetic fluxes interlinked inside the coil by the magnetic field generated from the cable is maximized. In order to maximize detection performance, it is necessary to clamp the cable.
Therefore, the conventional electromagnetic field sensor is to be searched when the cable to be searched is laid in a rack of the ceiling or the cable to be searched is buried in the ground and can not contact the cable to be searched. There is a problem that the electric field or the magnetic field can not be received by the search signal input to the cable, and the cable can not be searched at any intermediate portion.

  This invention was made in order to solve the above-mentioned subject, and even if it is not possible to contact an electromagnetic field sensor to the cable to be probed, the probe signal detected on the cable to be probed is detected. An electromagnetic field sensor for use in a cable probing system capable of probing.

  In the electromagnetic field sensor according to the present invention, a core made of a non-conductive nonmagnetic material, a winding around which the core is wound, and an electromagnetic induction based on a current of a search signal flowing through the cable generates the winding. The induced current is output through two leads drawn from both ends of the winding, and the voltage generated in the winding by electrostatic induction based on the voltage of a search signal applied to the cable is And an output unit for outputting via one lead wire drawn from an arbitrary point of the wire.

  In the disclosed electromagnetic field sensor, an electric field or a magnetic field can be detected from a distant place which can not be detected by the conventional electromagnetic field sensor.

(A) is a block diagram which shows schematic structure of the transmission side of a cable probing system, (b) is a block diagram which shows schematic structure of the receiving side of a cable probing system. (A) is a front view which shows schematic structure of the air core coil of the electromagnetic field sensor shown in FIG. 1, (b) is a rear view of the air core coil shown to Fig.2 (a), (c) is a figure. 2 (a) is a left side view and a right side view of the air core coil, FIG. 2 (d) is a plan view of the air core coil shown in FIG. 2 (a), and FIG. It is a bottom view of an air core coil shown. (A) is a front view which shows schematic structure of the housing | casing of the electromagnetic field sensor shown in FIG. 1, (b) is a rear view of the housing shown to Fig.3 (a), (c) is FIG. It is a left side view of a case shown to a), (d) is a right side view of a case shown to Fig.3 (a), (e) is a top view of a case shown to Fig.3 (a) FIG. 3 (f) is a bottom view of the case shown in FIG. 3 (a). (A) is explanatory drawing for demonstrating the positional relationship of the air core coil of an electromagnetic field sensor shown in FIG. 1, and a search cable, (b) is an arrow AA 'line shown to Fig.4 (a). FIG. (A) is a circuit diagram for the evaluation test of the winding of an electromagnetic field sensor, (b) is a table | surface which shows the result of characteristic evaluation of an electromagnetic field sensor. (A) is a circuit diagram for evaluation test of an electromagnetic field sensor in the case of using a lead wire to connect a transmitter and a search cable, (b) is a transmission CT for connection between a transmitter and a search cable FIG. 7 is a circuit diagram for an evaluation test of an electromagnetic field sensor in the case of using B. FIG. 7C is a table showing a result of comparative evaluation of characteristics of the electromagnetic field sensor. (A) is a sectional view of the air core coil of the electromagnetic field sensor according to the second embodiment taken along the line AA 'shown in FIG. 4 (a), and (b) according to the second embodiment It is sectional drawing of the arrow AA 'line shown to FIG. 4A in the other air core coil of an electromagnetic field sensor.

First Embodiment of the Present Invention
As shown in FIG. 5A, the route search system of the cable 100 transmits a current converter for transmitting an electrical signal (hereinafter referred to as a search signal) from the transmitter 10 to the conductor 101 or the shielding layer of the cable 100. The signal is applied via (CT: current transformer) 21 or a lead 22 and probed by detecting the probe signal at the receiver 40 via the electromagnetic field sensor 30 (receiving sensor) according to the present invention. In addition, the transmitter 10 and the receiver 40 have a product name "PTR600 power tracer" manufactured by TASCO, for example.

The transmitter 10 can be connected to various cables 100 (0 to 600 V, alternating current (AC) / direct current (DC)), and is a cable 100 to be searched (hereinafter referred to as a search cable 100 and The method of applying a search signal that generates a very weak induced current or voltage depending on the situation of
In the transmitter 10, a conductive clip is disposed at the end of the lead wire 22, and one lead wire 22a is connected to the conductor 101, the shielding layer or the ground wire of the probe cable 100, and the other lead wire 22b Is connected to the ground (grounded), thereby performing application of a voltage to the probe cable 100 and energization of a current.

  As shown in FIG. 1A, the transmitter 10 has a frequency of 33 kHz as a basic signal, and has a period of 1.15 msec as a period (frequency 868 Hz) and an interval of 400 msec as a period (frequency 2.5 Hz). transmitter 11 for transmitting a signal combining off, amplifier 12 for amplifying the signal input from transmitter 11, and a coupling capacitor for passing an AC signal among the signals input from amplifier 12 and blocking a DC signal 13 and an EMI (Electro Magnetic Interference) filter 14 which is a filter for eliminating electromagnetic interference.

  In the signal transmitted from the transmitter 11, an on / off signal with a frequency of 33 kHz and a period of 1.15 msec (frequency 868 Hz) is a signal that functions as a search signal, and an on / off with a period of 400 msec (frequency 2.5 Hz) The signal is a signal that functions as a buzzer sound and a lamp blink.

  In addition, a signal of frequency 1 kHz is superimposed on a basic signal of frequency 33 kHz as a search signal, applied from the transmitter 10 to the search cable 100, detected by the receiver 40, and installed around the search cable 100 It is intended to improve the reliability in the exploration of the exploration cable 100 by reducing the influence of external noises and the like generated by other cables and equipment installed around them.

  In the transmission CT 21, a winding of 20 turns (10 turns each on the left and right) is wound around a split type fillite core having an inner diameter of 27 mm. Although the number of turns of the winding wound around the fillite core is not limited to 20 turns, it is preferable to set it to 20 turns excellent in both characteristics of voltage application and current conduction according to experimental results. In addition, the transmission CT 21 according to the present embodiment has the cable 100 up to an outer diameter of 25 mm as a search target because the winding is wound around a filly core having an inner diameter of 27 mm. If it enlarges, it will not be restricted to the search cable 100 of this outside diameter.

  The electromagnetic field sensor 30 is a detector that detects a magnetic field generated based on a current flowing through the probe cable 100 and / or an electric field generated based on a voltage applied to the probe cable 100.

  The electromagnetic field sensor 30 has a core 31 made of a nonconductive nonmagnetic material (for example, polypropylene: polypropylene) and a core 31 as shown in FIG. 2, FIG. 3, FIG. 4 (a) and FIG. And an induction current generated in the winding 32 by electromagnetic induction based on the current of the probe signal flowing through the cable 100, the two lead wires drawn from both ends of the winding 32 (hereinafter referred to as the first 1) The voltage generated in the winding 32 by the electrostatic induction based on the voltage of the search signal applied to the cable 100 while being output through the leads 33a and 33b) is extracted from any point of the winding 32 It comprises an output section 33 for outputting via a lead (hereinafter referred to as a second lead 33c) of a book, and a case 34 for housing the core 31 and the winding 32.

The core 31 has a flat surface 31 a opposed to the probe cable 100 as shown in FIGS.
In addition, as shown in FIG. 2, the core 31 according to the present embodiment is, for example, a step 31b that prevents the wound winding 32 from coming off the core 31 in a rectangular solid of 22 mm long, 150 mm wide and 17 mm high. (1 mm in width, 1 mm in height) is provided on the outer periphery. That is, the core 31 is a rectangular solid having a length of 20 mm, a width of 148 mm, and a height of 15 mm, at the inside of the step 31 b where the winding 32 is wound.
Further, as shown in FIG. 2B, the step 31b has two notches 31c with a width of 2 mm for taking out the first lead wires 33a and 33b and the second lead wire 34a at the center upper and lower two points on the back side. Prepare for
In addition, although the core 31 which concerns on this embodiment consists of a substantially rectangular parallelepiped which each surface including the plane 31a is substantially rectangular shape, if it has the plane 31a opposed to the exploration cable 100, it will be restricted to a substantially rectangular parallelepiped. For example, it may be a substantially triangular prism whose side surface is the plane 31a.

The winding 32 is a coated conducting wire such as enameled wire, and as shown in FIGS. 2 and 4A, the winding 32 is an empty wire wound around the core 31 uniformly and densely along the longitudinal direction of the plane 31a of the core 31. A core coil is formed, and a voltage is induced in the core 31 by electromagnetic induction based on the current flowing in the probe cable 100, and an induced current is generated in response to a change in the magnetic field induced in the core 31, and the first lead wire 33a , 33b to output an induced current to the output unit 33.
In addition, the winding 32 can identify the whole of the winding 32 uniformly and densely wound as an electrode, and a static electricity based on a voltage applied to the probe cable 100 is applied to the electrode (winding 32). A voltage is generated by electric induction, and the voltage is output to the output unit 33 through the second lead 33c.
The second lead wire 33c according to the present embodiment is a coated wire such as an enameled wire welded to the winding 32, and in order to be close to the exploration cable 100 to suppress the influence of the inductance of the winding 32: As shown in FIG. 2 (b), welding is preferably performed substantially at the center of the coil.

  The output unit 33 is connected to the receiver 40, outputs an induced current generated in the winding 32 by electromagnetic induction to the receiver 40, and outputs a voltage generated in an electrode (winding 32) by electrostatic induction to the receiver 40. .

When the magnetic field is detected, the connection between the second lead wire 33c and the receiver 40 is cut off, and the magnetic field is detected by using the winding 32 as an air core coil, and through the first lead wires 33a and 33b. The output unit 33 outputs an induced current by electromagnetic induction to the receiver 40.
When detecting an electric field, the connection between the first lead wires 33a and 33b and the receiver 40 is cut off, the first lead wires 33a and 33b are short-circuited, and the electric field is detected using the winding 32 as an electrode. And outputs a voltage due to electrostatic induction from the output unit 33 to the receiver 40 via the second lead 33c.

The housing 34 is molded of resin and accommodates the core 31 around which the winding 32 is wound.
Further, as shown in FIG. 3, the housing 34 has a substantially rectangular parallelepiped outer shape, and has an opening 34 a at the center of the back surface, and the output portion 33 (first lead wires 33 a and 33 b, second lead wire 33c) are pulled out of the opening 34a.
In the case 34, for example, for a rectangular solid of 40 mm long, 150 mm wide and 40 mm high, each side of the front and back is chamfered at 1 mm, and a radius of 2 mm is attached to the corners of the front and back

In the receiver 40, the internal microprocessor automatically identifies only the signal transmitted from the transmitter 10, thereby dramatically improving the operability and reliability for searching the cable 100 under test. .
In the case where the closed circuit through the conductive portion of the probing cable 100 is configured, the probing of the cable under test 100 by the receiver 40 is carried out because almost no voltage is applied to the probing cable 100 and current flows. From the magnitude of the magnetic field generated based on this current, it is possible to search for the target cable 100.
On the other hand, in the case where a closed circuit through the conductive portion of the probe cable 100 is not configured, almost no current flows in the probe cable 100 and a voltage is applied, so the magnitude of the electric field generated based on this voltage It becomes possible to search for the target cable 100.

  As shown in FIG. 1B, the receiver 40 includes an electromagnetic field detection unit 41, a rectification circuit 42, a signal amplification / sensitivity adjustment unit 43, a filter 44, a signal level detection unit 45, and a notification unit 46. And have.

The electromagnetic field detection unit 41 includes a magnetic field detection unit 41a and an electric field detection unit 41b.
The magnetic field detection unit 41 a detects a magnetic field (induced current) from the induced current input from the electromagnetic field sensor 30, converts the detected induced current into a voltage, and outputs the voltage to the rectifying circuit 42.
The electric field detection unit 41 b detects an electric field (voltage) from the voltage input from the electromagnetic field sensor 30, and outputs the electric field to the rectification circuit 42.
In the detection of the magnetic field (induction current), the evaluation test was carried out for the case where the resonance circuit is configured and the case where the resonance circuit is not configured. It is preferable that the magnetic field detection unit 41a have a built-in resonant circuit because of its excellent performance.

The rectifier circuit 42 is composed of a first rectifier circuit 42a and a second rectifier circuit 42b.
The first rectifier circuit 42 a full-wave rectifies the voltage obtained by converting the induced current, which is input from the magnetic field detection unit 41 a, and outputs the rectified voltage to the signal amplification / sensitivity adjustment unit 43.
The second rectification circuit 42 b full-wave rectifies the voltage based on electrostatic induction, which is input from the electric field detection unit 41 b, and outputs the voltage to the signal amplification / sensitivity adjustment unit 43.

The signal amplification and sensitivity adjustment unit 43 includes a first signal amplification and sensitivity adjustment unit 43a and a second signal amplification and sensitivity adjustment unit 43b, and the rectification circuit 42 (a first rectification circuit 42a and a second rectification circuit) When the reception strength is strong, the amplification factor is 50 times the voltage input from 42b), and when the reception strength is weak, the amplification factor is 2.5 times and output to the filter 44.
The signal amplification / sensitivity adjustment unit 43 according to the present embodiment can optimize the compatibility with the electromagnetic field sensor 30 connected to the receiver 40 in the study of the specifications of the electromagnetic field sensor 30, so Although set, it is not limited to this amplification factor.

  The filter 44 includes a first filter 44a and a second filter 44b, and from the signal amplification / sensitivity adjustment unit 43 (first signal amplification / sensitivity adjustment unit 43a, second signal amplification / sensitivity adjustment unit 43b) It is a band pass filter (Band-pass filter (BPF)) which passes only a predetermined frequency (for example, 33 kHz / 868 Hz) among the input signals, and the signal of the predetermined frequency passed is sent to the signal level detection unit 45. Output.

  The signal level detection unit 45 includes a first signal level detection unit 45a and a second signal level detection unit 45b, and the filter 44 (first filter 44a, second filter 44b) is based on a predetermined threshold value. And detects the level of the signal input thereto, and outputs the detected signal level to the notification unit 46.

  The notification unit 46 sounds a buzzer and / or generates an LED (light-) according to the level of the signal input from the signal level detection unit 45 (the first signal level detection unit 45a and the second signal level detection unit 45b). (emitting diode) The operator is notified by lighting of a lamp or the like.

Here, the specifications of the electromagnetic field sensor 30 are considered.
First, the optimum number of turns of the winding 32 in the electromagnetic field sensor 30 is adjusted in combination with the receiver 40 using the evaluation test circuit shown in FIG. 5A, and the result is shown in FIG. 5B.

In the evaluation test, one lead 22a of the transmitter 10 is connected to the conductor 101 or shielding layer of the probe cable 100, and the other lead 22b of the transmitter 10 is connected (grounded) to the search A probe signal is applied from the transmitter 10 to the conductor 101 or shielding layer of the cable 100.
In the evaluation test, the electromagnetic field sensor 30 connected to the receiver 40 is gradually brought close to the probe cable 100 from a distance under the condition that current is supplied to the closed circuit, and the electromagnetic field sensor 30 (receiver 40) The distance from the probe cable 100 at the point where the sensor was detected was measured.

  Note that “one LED blinks” in the table shown in FIG. 5B is a case where the LED lamp as the notification unit 46 of the receiver 40 is turned on and the reaction is low. “Beep buzzer sounds (three LEDs blink)” means that three or more LED lamps as the notification unit 46 of the receiver 40 can be turned on or level determination is possible, and the reaction is good. In addition, “five LED blinks” is a case where five LED lamps as the notification unit 46 of the receiver 40 are lighted, and the reaction is very good.

  As shown in FIG. 5 (b), when the number of turns of the winding 32 is 20, the result is that detection of the magnetic field is possible with the distance between the probe cable 100 and the electromagnetic field sensor 30 being the most apart. It was obtained. For this reason, in the electromagnetic field sensor 30 according to the present embodiment, 20 turns are selected as the number of turns of the winding 32. The number of windings 32 according to the present embodiment is not limited to this number of turns, and it is preferable to adjust the number of turns according to the sensitivity of magnetic field detection required for the electromagnetic field sensor 30.

Next, in the equipment shown in FIGS. 6 (a) and 6 (b), a cable search device provided with the transmitter 10, the transmitting CT 21 or lead wire 22, the receiver 40, and the electromagnetic field sensor 30 according to the present embodiment. Search of cable 100 by (Example) and cable search device (comparative example) provided with transmitter 10, transmission CT 21 or lead wire 22, receiver 40 and conventional electromagnetic field sensor (clamp type sensor) 130 The results of verification of the comparison of performance are shown in FIG.
Here, the number of turns of the winding 32 in the electromagnetic field sensor 30 (example) according to the present embodiment and the conventional electromagnetic field sensor 130 (comparative example) is 20 turns.

  In the evaluation test, the electromagnetic field sensor 30 (example) or the electromagnetic field sensor 130 (comparative example) connected to the receiver 40 is gradually brought close to the probe cable 100 from a distance, and the electromagnetic field sensor 30 (example) or The distance from the probe cable 100 at the point where the electromagnetic field sensor 130 (comparative example) detected a magnetic field or an electric field was measured.

  In addition, the conventional electromagnetic field sensor 130 (comparative example) is disclosed by Unexamined-Japanese-Patent No. 2011-059070, consists of a nonmagnetic material which has electroconductivity, and clamps a cable in the state which clamped the said cable. The magnetic core is made of a substantially annular electrode that circumferentially surrounds, a magnetic core made of a magnetic material, and disposed outside the ring of the electrode through the insulator, a winding for winding the magnetic core, and a lead wire from the electrode And an output part drawn out from both ends of the winding by a lead wire, outputting from the output part an induced current generated in the winding by electromagnetic induction, and outputting from an output part a voltage generated in an electrode by electrostatic induction It is

The equipment shown in FIG. 6A is the case where the lead wire 22 is used to connect the transmitter 10 and the probe cable 100, and one lead wire 22a is connected to the conductor 101 of the probe cable 100, and the other The lead wire 22b of is connected (grounded) to the ground.
The equipment shown in FIG. 6B is a case where the transmission CT 21 is used to connect the transmitter 10 and the search cable 100.

The “sensitivity of the receiver” in the table shown in FIG. 6C is the case where the high sensitivity or the low sensitivity is switched by the sensitivity adjustment button of the receiver 40. Moreover, "the grounding of a search cable" is a case where both ends or one end of the search cable 100 are grounded. Further, “signal detection” is a case of detecting an induced current generated in the winding 32 by electromagnetic induction or a case of detecting a voltage generated in an electrode (winding 32) by electrostatic induction.
Furthermore, “three LED blinks” means that three or more LED lamps as the notification unit 46 of the receiver 40 can be lit or level determination is possible, and the reaction is good. In addition, “five LED blinks” is a case where five LED lamps as the notification unit 46 of the receiver 40 are lighted, and the reaction is very good.

As shown in FIG. 6C, the electromagnetic field sensor 30 (example) according to the present embodiment relates to the prior art in the case of detecting a magnetic field (induced current) and in the case of detecting an electric field (voltage). As compared with the electromagnetic field sensor 130 (comparative example), the result was obtained that the search was possible from a location distant from the search cable 100.
In particular, when the electromagnetic field sensor 30 (example) according to the present embodiment detects a magnetic field (induced current), if the sensitivity of the receiver 40 is increased, the distance between the probing cable 100 and the electromagnetic field sensor 30 is 1 m. It turns out that cable search is possible even if it is separated to some extent.

  As described above, the electromagnetic field sensor 30 according to the present embodiment includes the core 31 made of a non-conductive nonmagnetic material, the winding 32 around which the core 31 is wound, and the current of the exploration signal flowing through the exploration cable 100 While outputting the induced current generated in the winding 32 by the electromagnetic induction based on the two first lead wires 33a and 33b drawn from both ends of the winding 32, the voltage of the probing signal applied to the probing cable 100 And an output section 33 for outputting a voltage generated in the winding 32 by electrostatic induction based on the voltage via one second lead 33c drawn from an arbitrary point of the winding 32. Thereby, the electromagnetic field sensor 30 according to the present embodiment is a single component (air core coil) of the magnetic field generated based on the current flowing through the probing cable 100 and the electric field generated based on the voltage applied to the probing cable 100 Thus, the search operation of the cable 100 can be greatly simplified.

  In addition, the electromagnetic field sensor 30 according to the present embodiment has a flat surface 31a in which the core 31 is opposed to the probe cable 100, and the winding 32 is wound around the core 31 along the longitudinal direction of the flat surface 31a. When detecting the magnetic field based on the current of the probing signal generated so that the entire plane 31a opposed to the probing cable 100 is substantially equally spaced with respect to the probing cable 100 and goes around the periphery of the probing cable 100 The number of magnetic fluxes linked to the opening (inside the coil) of the air core coil can be increased as compared with the case of the air core coil, and the magnetic field can be detected with high sensitivity.

Here, in the conventional electromagnetic field sensor, when the probe cable 100 is clamped, an annular coil is formed, and the number of magnetic flux interlinking inside the coil due to the magnetic field generated from the probe cable 100 is the largest. Therefore, it is necessary to clamp the probing cable 100 in order to maximize the detection performance of the probing signal.
That is, in the conventional electromagnetic field sensor, when the probe cable 100 is not clamped, when separated from the probe cable 100, the magnetic flux is less likely to be linked inside the coil across the annular coil, and the flux linked to the coil Is dependent on the distance from the probe cable 100.

On the other hand, the electromagnetic field sensor 30 according to the present embodiment uses an air core coil suitable for detecting a high-frequency minute current, and has a length of the core 31 of a nonconductive nonmagnetic material having a substantially rectangular flat surface 31a. The winding 32 is wound uniformly and densely in the direction to form an air core coil having a large magnetic path cross sectional area of the coil.
Then, in the electromagnetic field sensor 30 according to the present embodiment, when the air core coil is arranged such that the coil cross section is in the direction orthogonal to the magnetic field by the search signal, magnetic flux is interlinked in the air core coil across the entire air core coil. The number of magnetic fluxes linked to the air core coil is less dependent on the distance from the probe cable 100, as compared with the coil of the conventional electromagnetic field sensor.

Therefore, the electromagnetic field sensor 30 according to the present embodiment can increase the magnetic path cross-sectional area of the air core coil with respect to the magnetic path cross-sectional area of the coil of the conventional electromagnetic field sensor, and the number of interlinkage magnetic flux It can be increased.
That is, the electromagnetic field sensor 30 according to the present embodiment is injected into the exploration cable 100 by arranging the air core coil so that the longitudinal direction of the core 31 (plane 31a) is parallel to the longitudinal direction of the exploration cable 100. The magnetic field generated by the search signal can be detected with high sensitivity from a distant place, and since the winding 32 serving as the electrode is along the search cable 100, the electric field can be detected efficiently.

  Further, the electromagnetic field sensor 30 according to the present embodiment can detect a magnetic field based on the current flowing in the probing cable 100 in a state of being separated from the probing cable 100 when current is supplied to the probing cable 100. It is possible to simplify the route finding operation of a cable laid out of the reach of the operator such as a buried cable or a ceiling without clamping the search cable 100.

  In addition, although the electromagnetic field sensor 30 according to the present embodiment uses an air core coil, it does not require a magnetic flux collecting core or an electrode used in a general electromagnetic field sensor. And cost can be reduced.

  In addition, if the electromagnetic field sensor 30 according to the present embodiment is specialized for use from a location away from the probing cable 100, the air core coil is enlarged and the number of turns of the winding 32 is increased Exploration performance can be improved.

  In particular, the electromagnetic field sensor 30 according to the present embodiment extends the air core coil in the longitudinal direction, and the width (height) of the air core coil in the short direction is 15 mm, so that the outer diameter of the probe cable 100 is 15 mm. If it is above and it is the conditions which can contact electromagnetic field sensor 30 with survey cable 100, distinction of desired survey cable 100 can be performed among a plurality of cables 100.

Second Embodiment of the Present Invention
7 (a) is a cross-sectional view taken along the line AA 'of FIG. 4 (a) in the air core coil of the electromagnetic field sensor according to the second embodiment, and FIG. 7 (b) is a second It is sectional drawing of the arrow AA 'line shown to FIG. 4A in the other air core coil of the electromagnetic field sensor which concerns on embodiment. 7 (a) and 7 (b), the same reference numerals as in FIG. 4 indicate the same or corresponding parts, and the description thereof will be omitted.

  In the first embodiment described above, as shown in FIG. 4B, the winding 32 is a coated wire, and the adjacent windings 32 are in close contact and wound around the core 31 in a single layer. There is an insulating portion between the conductors (cores) of the adjacent windings 32, and on the surface facing the probing cable 100, the electrodes are not planar but linear. For this reason, the electrode (winding 32) according to the first embodiment is not a perfect counter flat plate to the conductor 101 of the probe cable 100.

On the other hand, in the winding 32 according to the present embodiment, as shown in FIG. 7A, the adjacent windings 32 are in close contact with each other, and are wound around the core 31 as a lower layer. It is the structure of the two-layer winding wound as an upper layer between.
Thus, the electrode according to the present embodiment (the two-layer winding structure of the winding 32) is closer to a facing flat plate than the electrode according to the first embodiment (the single-layer winding structure of the winding 32), The facing area of the probe cable 100 with the conductor 101 can be expanded, the electric field can be detected efficiently, and the sensor can sufficiently function as an electric field sensor.

Furthermore, as shown in FIG. 7B, the winding 32 according to the present embodiment is in the form of a tape (for example, a copper tape), and adjacent windings 32 (conductors) overlap each other and are wound around the core 31. It may be turned.
Thereby, the electrode (tape-like winding 32) according to the present embodiment is closer to the opposing flat plate than the electrode (the two-layer winding structure of the normal winding 32) according to the present embodiment, The facing area of the cable 100 with the conductor 101 can be expanded, the electric field can be detected more efficiently, and the function as an electric field sensor can be sufficiently performed.

Reference Signs List 10 transmitter 11 transmitter 12 amplifier 13 coupling capacitor 14 EMI filter 21 CT for transmission
22 Lead 22a Single Lead 22b Other Lead 30 Electromagnetic Field Sensor 31 Core 31a Flat 31b Step 31c Notched Part 32 Winding 33 Output 33a, 33b First Lead 33c Second Lead 34 Case 34a opening 40 receiver 41 electromagnetic field detection unit 41a electric field detection unit 41b magnetic field detection unit 42 rectification circuit 42a first rectification circuit 42b second rectification circuit 43 signal amplification and sensitivity adjustment unit 43a first signal amplification and sensitivity adjustment Unit 43b Second signal amplification / sensitivity adjustment unit 44 Filter 44a First filter 44b Second filter 45 Signal level detection unit 45a First signal level detection unit 45b Second signal level detection unit 46 Notification unit 100 Cable 101 Conductor 130 electromagnetic field sensor

Claims (3)

In an electromagnetic field sensor receiving a probe signal for probing a cable,
A nonconductive nonmagnetic core and
A winding winding the core;
An induced current generated in the winding by electromagnetic induction based on a current of an exploration signal flowing through the cable is output through two leads drawn from both ends of the winding, and an exploration signal applied to the cable An output unit for outputting a voltage generated in the winding by electrostatic induction based on a voltage of the voltage via one lead wire drawn from an arbitrary point of the winding;
Equipped with
The core has a plane facing the cable,
The electromagnetic field sensor according to claim 1, wherein the winding is wound around the core along a longitudinal direction of the plane . In an electromagnetic field sensor receiving a probe signal for probing a cable,
A nonconductive nonmagnetic core and
A winding winding the core;
An induced current generated in the winding by electromagnetic induction based on a current of an exploration signal flowing through the cable is output through two leads drawn from both ends of the winding, and an exploration signal applied to the cable An output unit for outputting a voltage generated in the winding by electrostatic induction based on a voltage of the voltage via one lead wire drawn from an arbitrary point of the winding;
Equipped with
The electromagnetic field sensor according to claim 1, wherein the windings are wound in close contact with each other as the lower layer around the core and are wound as the upper layer between adjacent windings in the lower layer. In an electromagnetic field sensor receiving a probe signal for probing a cable,
A nonconductive nonmagnetic core and
A winding winding the core;
An induced current generated in the winding by electromagnetic induction based on a current of an exploration signal flowing through the cable is output through two leads drawn from both ends of the winding, and an exploration signal applied to the cable An output unit for outputting a voltage generated in the winding by electrostatic induction based on a voltage of the voltage via one lead wire drawn from an arbitrary point of the winding;
Equipped with
The electromagnetic field sensor according to claim 1, wherein the winding is in the form of a tape, and adjacent windings are superimposed on each other and wound around the core.