WO2020049883A1 - Electric current measurement apparatus and electric current measurement method - Google Patents

Electric current measurement apparatus and electric current measurement method Download PDF

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Publication number
WO2020049883A1
WO2020049883A1 PCT/JP2019/028910 JP2019028910W WO2020049883A1 WO 2020049883 A1 WO2020049883 A1 WO 2020049883A1 JP 2019028910 W JP2019028910 W JP 2019028910W WO 2020049883 A1 WO2020049883 A1 WO 2020049883A1
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Prior art keywords
measured
sensor
conductor
current
electric wire
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PCT/JP2019/028910
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French (fr)
Japanese (ja)
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哲也 吉池
池田　正和
謙太郎 中島
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日置電機株式会社
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof

Definitions

  • the present invention relates to a current measuring device and a current measuring method.
  • a clamp meter is used to measure the current of an electric wire to be measured in a live state.
  • a clamp sensor which is a current sensor, is attached to an electric wire to be measured, and the current of the electric wire to be measured is measured.
  • Some clamp sensors include a magnetic core that forms a closed magnetic path arranged in a ring around the electric wire to be measured, and a magnetic sensor including a Hall element and a detection coil that detect the magnetism of the magnetic core.
  • a cable type flexible current sensor There is also a cable type flexible current sensor.
  • the first proposal is a measuring device provided with a terminal capable of contacting a coating of a wire to be measured, the terminal having a magnetic sensor for detecting a magnetic field generated by a current flowing through the wire to be measured, and a magnetic field detected by the magnetic sensor. And, provided an operating unit that can input or select the standard information of the measurement target wire, based on the information of the thickness of the coating of the measurement target wire and the thickness of the conductor determined by the standard of the measurement target wire, the distance to the conductor and And the magnetic field detected by the magnetic sensor to calculate the current of the electric wire to be measured.
  • Another proposal is a current measuring device described in Patent Literature 1, in which a magnetic detection coil having the same shape is parallel to the electric wire to be measured, and the relative distance to the electric wire to be measured is shifted by a predetermined dimension.
  • a magnetic sensor is provided to calculate the distance to the conductor of the measurement target wire from the difference between the magnetic fields detected by the two magnetic detection coils, and to calculate the current flowing through the measurement target wire from the obtained distance and the detected magnetic field. is there.
  • the present invention proposes a current measuring device and a current measuring method which can measure a current without clamping a sensor to an electric wire to be measured, and which is compact, does not require a complicated measuring operation, and can perform accurate measurement.
  • the purpose is to:
  • a first aspect of the present invention is a current measuring device, a proximity sensor that obtains information on the distance to a conductor of a measurement target wire, and a magnetic sensor that obtains information on a magnetic field generated by a current flowing through the measurement target wire. And a calculation processing unit that calculates a current value flowing through the measurement target wire from information on the magnetic field obtained by the magnetic sensor and information on a distance to the conductor of the measurement target wire obtained by the proximity sensor.
  • the proximity sensor is an eddy current sensor, and the planar shape of the coil of the eddy current sensor is a shape in which the longitudinal direction of the coil extends in the extension direction of the electric wire to be measured, and a plurality of coils are stacked. Preferably, it is configured.
  • Another aspect of the present invention is a current measuring method, in which a magnetic sensor acquires information on a magnetic field generated by a current flowing through a measurement target wire, and an eddy current sensor acquires information on a distance to a conductor of the measurement target wire.
  • the arithmetic processing unit calculates the value of the current flowing through the electric wire to be measured from the acquired information on the magnetic field and the information on the distance of the electric wire to be measured to the conductor.
  • the proximity sensor allows the distance to the conductor of the electric wire to be measured to be known more accurately, so that accurate current measurement is possible.
  • the sensor unit is provided with the magnetic sensor and the proximity sensor, a portable and portable device can be provided.
  • FIG. 4 is a diagram illustrating a configuration in which an eddy current sensor and a Hall element sensor of a current sensor are mounted.
  • FIG. 1 is a diagram illustrating a configuration of a current measuring device according to a first embodiment of the present invention.
  • An eddy current sensor 11 detects a distance of a wire to be measured to a conductor 2, and detects the detected distance and a magnetic field.
  • a configuration is shown in which a current flowing through the conductor 2 of the electric wire to be measured is detected from a magnetic field detected by the Hall element sensor 12 as a sensor.
  • the current measuring device includes a sensor unit 10 and a measuring device main body 20.
  • the sensor unit 10 includes an eddy current sensor 11 that is a proximity sensor that detects a distance of the electric wire to be measured to the conductor 2 and a Hall element sensor 12 that is a magnetic sensor that detects a magnetic field generated by a current flowing through the conductor 2 of the electric conductor to be measured.
  • the measuring device main body 20 includes an analog / digital converter 23 to which a signal from the eddy current sensor 11 is input, an analog / digital converter 24 to which a signal from the Hall element sensor 12 is input, and the analog / digital converters 23 and 24.
  • (Central Processing Unit) 26 as an arithmetic processing circuit to which digital signals are input, a memory 27 for storing programs or data, operation results, and the like, and connected to the CPU 26 via an interface (I / O) 28.
  • An operation unit 31, a communication unit 32, and a display unit 33 are provided.
  • the operation of the current measuring device shown in FIG. 1 will be described.
  • the signal output from the eddy current sensor 11 is converted into a digital signal by the analog / digital converter 23 and input to the CPU 26.
  • a signal output from the Hall element sensor 12 is converted into a digital signal by an analog / digital converter 24 and input to the CPU 26.
  • the CPU 26 calculates the distance between the eddy current sensor and the conductor 2 of the electric wire to be measured based on the signal from the eddy current sensor 11 based on the program stored in the memory 27, and measures the distance and the measurement from the Hall element sensor 12. Based on information on the magnetic field generated by the current flowing through the conductor 2 of the target electric wire, the value of the current flowing through the conductor 2 of the target electric wire is calculated and output and displayed on the display unit 33.
  • FIG. 2 is a schematic diagram illustrating the principle of current detection according to the present invention.
  • the eddy current sensor 11 and the Hall element sensor 12 are provided on a substrate 13 of the current sensor 10.
  • the eddy current sensor 11 and the Hall element sensor 12 are provided on the substrate 13 in the axial direction of the conductor 2 of the electric wire to be measured. It is provided in close proximity.
  • an alternating current I flows through the conductor 2 of the electric wire to be measured. Due to the current I, a circumferential induction magnetic field is generated around the axis of the conductor 2. This induction magnetic field is a magnetic field clockwise with respect to the direction of the current flowing through the conductor 2. This induction magnetic field can be detected by the Hall element sensor 12 having a magnetic flux sensing surface orthogonal to the magnetic flux.
  • the eddy current sensor 11 changes the impedance of the detection coil due to the eddy current generated on the surface of the opposing conductor 2.
  • This is a proximity sensor that detects a distance.
  • the magnetic field generated by the eddy current sensor 11 is formed in a cross-sectional direction orthogonal to the axis of the conductor 2, and the direction is also orthogonal to the induced magnetic field generated by the current flowing through the conductor 2. I do.
  • the frequency of the magnetic field generated by the eddy current sensor 11 is higher than several kHz, the frequency of the induced magnetic field generated by the current flowing through the conductor 2 detected by the Hall element sensor 12, that is, the commercial frequency of 50 Hz or 60 Hz
  • the detection band is different from the frequency. Therefore, the magnetic field generated by the current in the conductor 2 and the magnetic field of the eddy current sensor 11 do not affect each other, and have different frequencies. Therefore, it is possible to separate the detection signal through a filter.
  • information on the distance to the conductor 2 is obtained from the signal of the eddy current sensor 11, and information on the induced magnetic field of the current flowing through the conductor 2 is obtained from the signal of the Hall element sensor 12.
  • the current I flowing through the conductor 2 is expressed by the following equation (1) according to Ampere's law.
  • I 2 ⁇ rH (1)
  • H the strength of the magnetic field (magnetic field around the conductor)
  • r the distance between the measurement point of H and the conductor H is the definition of magnetic flux density and magnetic permeability expressed by the following equation (2) Is done.
  • H B / ⁇ 0 (2)
  • the magnetic permeability ⁇ 0 is the magnetic permeability in the air.
  • the magnetic permeability of the air is different from the magnetic permeability of the vacuum, but may be treated as the same. the ⁇ 0 is used.
  • the above calculation is a method of theoretically obtaining a current value
  • the following correction may be performed to reduce variations due to characteristics such as insulation coating of the electric wire, thickness of the electric wire, and location.
  • a plurality of types of wires having different insulation coating thicknesses are prepared, and the distance detected by the proximity sensor 11 is corrected.
  • a known current is caused to flow through this electric wire, and a correction formula is created so as to be equal to the actually flowing current, and is stored in the memory 27.
  • the displayed current value is corrected using the correction formula stored in the memory 27.
  • the eddy current sensor 11 detects that the inductance of the detection coil of the sensor changes due to the eddy current generated in the conductor 2, and the magnetic field generated by the detection coil of the eddy current sensor 11 leaks out of the conductor 2. Therefore, it is necessary to take measures to prevent the sensitivity from decreasing.
  • the shape of the detection coil of the eddy current sensor 11 is such that a 10-turn conductor is formed on the substrate, the longitudinal direction is the axial direction of the conductor 2, and the short direction is the width direction of the conductor 2. This detection coil was formed into a rectangular shape and laminated in ten layers. The respective layers were connected to each other by through holes.
  • the length and width of this detection coil was 6 ⁇ 3 mm. Since the magnetic field leakage is small in the width direction of the conductor 2 of the electric wire to be measured and the magnetic coupling is long in the axial direction of the conductor 2, the sensitivity as the eddy current sensor 11 can be improved.
  • FIG. 4 is a schematic diagram for explaining a structure for mounting the eddy current sensor 11 and the Hall element sensor 12 further.
  • the eddy current sensor 11 has detection coils stacked in multiple layers, and the magnetic flux sensing direction of the detection coils is orthogonal to the axial direction of the conductor 2 of the electric wire to be measured.
  • the stacked body of the stacked detection coils is attached to the substrate 13 of the sensor unit 10.
  • the magnetic flux sensing direction of the Hall element sensor is parallel to the axial direction of the conductor 2 and orthogonal to the magnetic flux sensing direction of the detection coil, so that the magnetic flux sensitivity sensing direction of the Hall element sensor is orthogonal to the substrate 13.
  • a substrate on which the Hall element sensor 12 is mounted is provided in a direction perpendicular to the substrate 13 so that the Hall element sensor 12 is mounted thereon.
  • the shape of the detection coil of the eddy current sensor is a rectangle of 6 ⁇ 3 mm, but may be an ellipse or a rhombus whose shape is flat in the axial direction of the conductor 2.
  • the number of layers is set to 10, the number of layers can be selected as needed.
  • the sensitivity of the eddy current sensor 11 depends on the strength of the magnetic coupling between the detection coil and the conductor 2 of the electric wire to be measured. The highest sensitivity is obtained when the detection coil is parallel to the conductor, that is, when the magnetic field generated by the detection coil is perpendicular to the conductor. On the other hand, when the detection coil is inclined with respect to the conductor, the magnetic coupling is weakened, and the sensitivity is reduced. For this reason, by providing a plurality of eddy current sensors 11, even if the conductor is inclined with respect to the conductor 2 of the electric wire to be measured, the uncertainty due to the inclination can be compensated.
  • the contact surface of the current sensor 10 with the electric wire to be measured may be formed so that the eddy current sensor 11 and the electric wire to be measured can be in contact with each other without tilting.
  • the surface to be contacted with the electric wire to be measured may have a shape having grooves in the axial direction.
  • a Hall element sensor is used as the magnetic sensor, but a magnetic sensor using an inductance may be used.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Measurement Of Current Or Voltage (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

Provided is a non-clamp-form electric current measurement apparatus with which it is possible to measure a current in an electrical wire to be measured without clamping the electrical wire to be measured. The present invention comprises a proximity sensor 11 that acquires information pertaining to the distance from an electrical wire to be measured to a conductor, and a magnetism sensor 12 that acquires information pertaining to a magnetic field produced due to a current flowing to the electrical wire to be measured. A measurement apparatus body 20 comprises a CPU 26 serving as a computation processing circuit that computes a current value flowing to the electrical wire to be measured from the information pertaining to a magnetic field as acquired by the magnetism sensor 12 and the information pertaining to the distance from the electrical wire to be measured to the conductor as acquired by the proximity sensor 11.

Description

電流測定装置および電流測定方法Current measuring device and current measuring method
　本発明は、電流測定装置および電流測定方法に関する。 The present invention relates to a current measuring device and a current measuring method.
　活線状態の測定対象電線の電流を測定するものとしてクランプメータが用いられている。
　このクランプメータは、測定対象電線に電流センサであるクランプセンサを装着して測定対象電線の電流を測定する。クランプセンサには、測定対象電線の周りに環状に配列される閉鎖磁路を形成する磁気コアと磁気コアの磁気を検出するホール素子や検出コイルからなる磁気センサを備えたものがある。また、ケーブルタイプのフレキシブル電流センサもある。 2. Description of the Related Art A clamp meter is used to measure the current of an electric wire to be measured in a live state.
In this clamp meter, a clamp sensor, which is a current sensor, is attached to an electric wire to be measured, and the current of the electric wire to be measured is measured. Some clamp sensors include a magnetic core that forms a closed magnetic path arranged in a ring around the electric wire to be measured, and a magnetic sensor including a Hall element and a detection coil that detect the magnetism of the magnetic core. There is also a cable type flexible current sensor.
　いずれも、活線状態にある測定対象電線の電流を測定するためには、クランプセンサを測定対象電線に周回させて取り付けるための空間が測定対象電線の周囲になければならず、たとえば、壁などに測定対象電線が外せないように取り付けられているような場所では、クランプセンサを用いた測定ができない。 In any case, in order to measure the current of the wire under test in the live state, there must be a space around the wire under test to mount the clamp sensor around the wire under test, such as a wall. In places where the electric wire to be measured is attached so that it cannot be removed, measurement using the clamp sensor cannot be performed.
　このような課題を解決するために、測定対象電線に接近させてセンサをクランプすることなく、測定対象電線の電流を測定しようとする電流測定装置の提案がある。 解決 In order to solve such a problem, there is a proposal of a current measuring device which measures the current of the electric wire to be measured without approaching the electric wire to be measured and clamping the sensor.
　第一の提案は、測定対象電線の被覆に接触できる端子を備えた測定装置であって、端子に測定対象電線に流れる電流によって生ずる磁界を検出する磁気センサを備え、この磁気センサで検出した磁界と、測定対象電線の規格情報を入力あるいは選択できる操作部を設けて、測定対象電線の規格によって定まる測定対象電線の被覆の厚さ、導体の太さの情報に基づいて、導体への距離と、磁気センサで検出した磁界とから、測定対象電線の電流を演算するものである。
　他の提案は、特許文献１に記載の電流測定装置であって、同一形状の磁気検出コイルを測定対象電線と平行に、かつ、測定対象電線への相対距離を所定寸法だけずらした状態にした磁気センサを設け、ふたつの磁気検出コイルの検出した磁界の差から、測定対象電線の導体までの距離を求め、求めた距離と、検出した磁界とから測定対象電線に流れる電流を演算するものである。 The first proposal is a measuring device provided with a terminal capable of contacting a coating of a wire to be measured, the terminal having a magnetic sensor for detecting a magnetic field generated by a current flowing through the wire to be measured, and a magnetic field detected by the magnetic sensor. And, provided an operating unit that can input or select the standard information of the measurement target wire, based on the information of the thickness of the coating of the measurement target wire and the thickness of the conductor determined by the standard of the measurement target wire, the distance to the conductor and And the magnetic field detected by the magnetic sensor to calculate the current of the electric wire to be measured.
Another proposal is a current measuring device described in Patent Literature 1, in which a magnetic detection coil having the same shape is parallel to the electric wire to be measured, and the relative distance to the electric wire to be measured is shifted by a predetermined dimension. A magnetic sensor is provided to calculate the distance to the conductor of the measurement target wire from the difference between the magnetic fields detected by the two magnetic detection coils, and to calculate the current flowing through the measurement target wire from the obtained distance and the detected magnetic field. is there.
特開平７－１５９４４９号公報JP-A-7-159449
　上述の第一の電流測定装置は、測定する電線の規格情報を入力する、あるいは規格情報を選択する必要がある。測定対象電線の規格がわからない場合には、測定対象電線の導体までの距離が決まらないので測定値の演算ができない。また、作業者は、測定の都度、測定対象電線の規格情報を入力あるいは選択しなければならないので、作業が煩雑となるきらいがある。
　また、特許文献１に記載の電流測定装置では、磁界を検出するふたつの磁気検出コイルを、測定対象に対して検出できる磁界に有意な差がでる距離に離して設ける必要がある。
　このことは、ふたつの磁気検出コイルが設けられているセンサ部分が測定対象電線に対して相当な距離を必要とするので、大型化することを示しており、現場で使用するクランプメータの使用状況にそぐわない課題がある。 In the first current measuring device described above, it is necessary to input standard information of an electric wire to be measured or to select standard information. When the standard of the electric wire to be measured is not known, the distance to the conductor of the electric wire to be measured is not determined, so that the measurement value cannot be calculated. Further, the operator must input or select the standard information of the electric wire to be measured every time the measurement is performed, so that the operation may be complicated.
Further, in the current measuring device described in Patent Literature 1, it is necessary to provide two magnetic detection coils for detecting a magnetic field at a distance where a significant difference occurs in a magnetic field that can be detected with respect to a measurement target.
This indicates that the sensor portion provided with the two magnetic detection coils requires a considerable distance from the electric wire to be measured, and thus the size of the sensor becomes large. There is a problem that does not fit.
　本発明は、測定対象電線にセンサをクランプすることなく、電流を測定することができ、しかも小型で測定作業も煩わしくなく、また、正確な測定が可能な電流測定装置および電流測定方法を提案することを目的とする。 The present invention proposes a current measuring device and a current measuring method which can measure a current without clamping a sensor to an electric wire to be measured, and which is compact, does not require a complicated measuring operation, and can perform accurate measurement. The purpose is to:
　本発明の第一の側面は、電流測定装置であって、測定対象電線の導体への距離の情報を取得する近接センサと、測定対象電線に流れる電流によって生ずる磁界の情報を取得する磁気センサとを備え、磁気センサで取得した磁界の情報と、近接センサが取得した測定対象電線の導体への距離の情報とから、測定対象電線に流れる電流値を演算する演算処理部を備えていることを特徴とする。 A first aspect of the present invention is a current measuring device, a proximity sensor that obtains information on the distance to a conductor of a measurement target wire, and a magnetic sensor that obtains information on a magnetic field generated by a current flowing through the measurement target wire. And a calculation processing unit that calculates a current value flowing through the measurement target wire from information on the magnetic field obtained by the magnetic sensor and information on a distance to the conductor of the measurement target wire obtained by the proximity sensor. Features.
　なお、近接センサは、渦電流センサであり、渦電流センサのコイルの平面形状が前記測定対象電線の伸長方向にそのコイルの長手方向が伸長した形状であって、複数枚のコイルを積層して構成されていることが好ましい。 The proximity sensor is an eddy current sensor, and the planar shape of the coil of the eddy current sensor is a shape in which the longitudinal direction of the coil extends in the extension direction of the electric wire to be measured, and a plurality of coils are stacked. Preferably, it is configured.
　本発明の他の側面は、電流測定方法であって、磁気センサが測定対象電線に流れる電流により生ずる磁界の情報を取得し、渦電流センサが測定対象電線の導体への距離の情報を取得し、演算処理部が、取得した磁界の情報と、測定対象電線の導体への距離の情報とから、測定対象電線に流れる電流の値を演算することを特徴とする。 Another aspect of the present invention is a current measuring method, in which a magnetic sensor acquires information on a magnetic field generated by a current flowing through a measurement target wire, and an eddy current sensor acquires information on a distance to a conductor of the measurement target wire. The arithmetic processing unit calculates the value of the current flowing through the electric wire to be measured from the acquired information on the magnetic field and the information on the distance of the electric wire to be measured to the conductor.
　近接センサによって、測定対象電線の導体までの距離がより正確にわかるので、正確な電流測定が可能である。また、センサ部に、磁気センサと近接センサとを設けるので、ハンディであって、可搬の装置とすることも可能となる。 (4) The proximity sensor allows the distance to the conductor of the electric wire to be measured to be known more accurately, so that accurate current measurement is possible. In addition, since the sensor unit is provided with the magnetic sensor and the proximity sensor, a portable and portable device can be provided.
本発明の第一の実施形態の電流測定装置の構成を示す図である。It is a figure showing the composition of the current measuring device of a first embodiment of the present invention. 本発明の測定原理を説明する模式図である。It is a schematic diagram explaining the measurement principle of the present invention. 渦電流センサが積層されたコイルからなることを説明する図である。It is a figure explaining that an eddy current sensor consists of laminated coils. 電流センサの渦電流センサとホール素子センサとが取り付けられた構成を説明する図である。FIG. 4 is a diagram illustrating a configuration in which an eddy current sensor and a Hall element sensor of a current sensor are mounted.
　以下図面を参照して本発明の実施の形態を説明する。図１は、本発明の第一実施の形態の電流測定装置の構成を示す図であり、渦電流センサ１１によって、測定対象電線の導体２までの距離を検出し、その検出した距離と、磁気センサであるホール素子センサ１２で検出した磁界から、測定対象電線の導体２に流れる電流を検出する構成を示している。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a current measuring device according to a first embodiment of the present invention. An eddy current sensor 11 detects a distance of a wire to be measured to a conductor 2, and detects the detected distance and a magnetic field. A configuration is shown in which a current flowing through the conductor 2 of the electric wire to be measured is detected from a magnetic field detected by the Hall element sensor 12 as a sensor.
　本実施の形態の電流測定装置は、センサ部１０と、測定装置本体２０とから構成されている。
　センサ部１０は、測定対象電線の導体２への距離を検出する近接センサである渦電流センサ１１と、測定対象導体の導体２を流れる電流によって生ずる磁界を検出する磁気センサであるホール素子センサ１２とを備えている。測定装置本体２０は、渦電流センサ１１からの信号が入力されるアナログディジタル変換器２３と、ホール素子センサ１２からの信号が入力されるアナログディジタル変換器２４と、このアナログディジタル変換器２３、２４のディジタル信号が入力される演算処理回路としてのＣＰＵ（Central Processing Unit)２６と、プログラムあるいはデータ、演算結果等を記憶するメモリ２７と、ＣＰＵ２６にインタフェース（Ｉ／Ｏ）２８を介して接続されている操作部３１と、通信部３２と、表示部３３とを備えている。 The current measuring device according to the present embodiment includes a sensor unit 10 and a measuring device main body 20.
The sensor unit 10 includes an eddy current sensor 11 that is a proximity sensor that detects a distance of the electric wire to be measured to the conductor 2 and a Hall element sensor 12 that is a magnetic sensor that detects a magnetic field generated by a current flowing through the conductor 2 of the electric conductor to be measured. And The measuring device main body 20 includes an analog / digital converter 23 to which a signal from the eddy current sensor 11 is input, an analog / digital converter 24 to which a signal from the Hall element sensor 12 is input, and the analog / digital converters 23 and 24. (Central Processing Unit) 26 as an arithmetic processing circuit to which digital signals are input, a memory 27 for storing programs or data, operation results, and the like, and connected to the CPU 26 via an interface (I / O) 28. An operation unit 31, a communication unit 32, and a display unit 33 are provided.
　図１に示した電流測定装置の動作を説明する。
　渦電流センサ１１から出力される信号は、アナログディジタル変換器２３でディジタル信号に変換され、ＣＰＵ２６に入力される。また、ホール素子センサ１２から出力される信号はアナログディジタル変換器２４でディジタル信号に変換され、ＣＰＵ２６に入力される。ＣＰＵ２６は、メモリ２７に記憶されたプログラムに基づき、渦電流センサ１１からの信号から、渦電流センサと測定対象電線の導体２との距離を演算し、この距離と、ホール素子センサ１２からの測定対象電線の導体２を流れる電流によって生ずる磁界の情報とに基づいて、測定対象電線の導体２を流れる電流値を演算して、表示部３３に出力表示する。 The operation of the current measuring device shown in FIG. 1 will be described.
The signal output from the eddy current sensor 11 is converted into a digital signal by the analog / digital converter 23 and input to the CPU 26. Further, a signal output from the Hall element sensor 12 is converted into a digital signal by an analog / digital converter 24 and input to the CPU 26. The CPU 26 calculates the distance between the eddy current sensor and the conductor 2 of the electric wire to be measured based on the signal from the eddy current sensor 11 based on the program stored in the memory 27, and measures the distance and the measurement from the Hall element sensor 12. Based on information on the magnetic field generated by the current flowing through the conductor 2 of the target electric wire, the value of the current flowing through the conductor 2 of the target electric wire is calculated and output and displayed on the display unit 33.
　図２に基づいて、本発明の電流検出の原理を説明する。図２は、本発明の電流検出の原理を説明する模式図である。
　渦電流センサ１１と、ホール素子センサ１２とは、電流センサ１０の基板１３に設けられており、渦電流センサ１１とホール素子センサ１２とは、基板１３に測定対象電線の導体２の軸方向に近接して設けられている。 The principle of current detection according to the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram illustrating the principle of current detection according to the present invention.
The eddy current sensor 11 and the Hall element sensor 12 are provided on a substrate 13 of the current sensor 10. The eddy current sensor 11 and the Hall element sensor 12 are provided on the substrate 13 in the axial direction of the conductor 2 of the electric wire to be measured. It is provided in close proximity.
　ここで、測定対象電線の導体２には、交流の電流Ｉが流れる。この電流Ｉにより、導体２の軸周りに円周状の誘導磁界が生ずる。この誘導磁界は、導体２に流れる電流方向に対して時計周りの磁界である。この誘導磁界は、磁束に直交する磁束感知面を有するホール素子センサ１２によって検出できる。 Here, an alternating current I flows through the conductor 2 of the electric wire to be measured. Due to the current I, a circumferential induction magnetic field is generated around the axis of the conductor 2. This induction magnetic field is a magnetic field clockwise with respect to the direction of the current flowing through the conductor 2. This induction magnetic field can be detected by the Hall element sensor 12 having a magnetic flux sensing surface orthogonal to the magnetic flux.
　一方、渦電流センサ１１は、検出コイルに数ＭＨｚの高周波の一定電流を流すと、対向する導体２の表面に生ずる渦電流によって、検出コイルのインピーダンスが変化することで、検出コイルと導体との距離を検出する近接センサである。
　この渦電流センサ１１による磁界は、図２に示されるように、導体２の軸に直交する断面方向に形成されるものであり、その方向は、導体２に流れる電流によって生ずる誘導磁界にも直交する。そして、渦電流センサ１１によって生ずる磁界の周波数は、数ｋＨｚより高い周波数であるため、ホール素子センサ１２が検出する導体２を流れる電流によって生ずる誘導磁界の周波数、すなわち、商用周波数である５０Ｈｚあるいは６０Ｈｚの周波数とは検出帯域が異なっている。
　したがって、導体２の電流によって生ずる磁界と渦電流センサ１１の磁界とは、相互に影響を及ぼすものではなく、また、周波数が異なるので、検出信号をフィルタを介することによって、分離することが可能であって、渦電流センサ１１の信号から、導体２までの距離の情報が得られ、ホール素子センサ１２の信号から、導体２に流れる電流の誘導磁界の情報が得られる。 On the other hand, when a high-frequency constant current of several MHz is applied to the detection coil, the eddy current sensor 11 changes the impedance of the detection coil due to the eddy current generated on the surface of the opposing conductor 2. This is a proximity sensor that detects a distance.
As shown in FIG. 2, the magnetic field generated by the eddy current sensor 11 is formed in a cross-sectional direction orthogonal to the axis of the conductor 2, and the direction is also orthogonal to the induced magnetic field generated by the current flowing through the conductor 2. I do. Since the frequency of the magnetic field generated by the eddy current sensor 11 is higher than several kHz, the frequency of the induced magnetic field generated by the current flowing through the conductor 2 detected by the Hall element sensor 12, that is, the commercial frequency of 50 Hz or 60 Hz The detection band is different from the frequency.
Therefore, the magnetic field generated by the current in the conductor 2 and the magnetic field of the eddy current sensor 11 do not affect each other, and have different frequencies. Therefore, it is possible to separate the detection signal through a filter. Thus, information on the distance to the conductor 2 is obtained from the signal of the eddy current sensor 11, and information on the induced magnetic field of the current flowing through the conductor 2 is obtained from the signal of the Hall element sensor 12.
　ホール素子センサ１２で検出した誘導磁界と渦電流センサが検出した導体までの距離に基づいて、導体２の電流が求められる原理を説明する。 The principle by which the current of the conductor 2 is obtained based on the induction magnetic field detected by the Hall element sensor 12 and the distance to the conductor detected by the eddy current sensor will be described.
　導体２に流れる電流Ｉは、アンペールの法則により、次の（１）式で表される。
　　Ｉ＝２πｒＨ　　　　　　　　　　　　…（１）
　ここで、Ｈは、磁場（導体の周りの磁場）の強さ
　　　　　ｒは、Ｈの測定箇所と、導体との距離
　Ｈは、磁束密度と透磁率の定義式で次の（２）式で表される。
　　Ｈ＝Ｂ／μ０　　　　　　　　　　　　　…（２）
　ここで、透磁率μ０は、空気中の透磁率であるが、空気の透磁率は、真空の透磁率とは異なるが、同じであるとして扱って差し支えないので、計算では真空中の透磁率μ０を用いる。
　Ｂは、ホール素子センサが検出する磁束密度であるが、磁気センサで計測してえられた磁場（導体周り）の強度Ｘと等しいと考えられ、また、導体との距離ｒをＹとおけば、電流Ｉは次の（３）式で表される。
Figure JPOXMLDOC01-appb-M000001
 　真空中の透磁率μ０は、μ０＝４π×１０－７であるから、導体２を流れる電流値Ｉは、
Figure JPOXMLDOC01-appb-M000002
 　により、渦電流センサ１１から得られた距離Ｙ（Ｙ＝ｒ）と、ホール素子センサ１２とから得られた磁界の強さ（Ｘ）から、導体２の電流値を求めることができる。 The current I flowing through the conductor 2 is expressed by the following equation (1) according to Ampere's law.
I = 2πrH (1)
Here, H is the strength of the magnetic field (magnetic field around the conductor) r is the distance between the measurement point of H and the conductor H is the definition of magnetic flux density and magnetic permeability expressed by the following equation (2) Is done.
H = B / μ 0 (2)
Here, the magnetic permeability μ 0 is the magnetic permeability in the air. The magnetic permeability of the air is different from the magnetic permeability of the vacuum, but may be treated as the same. the μ 0 is used.
B is the magnetic flux density detected by the Hall element sensor, which is considered to be equal to the intensity X of the magnetic field (around the conductor) measured by the magnetic sensor, and if the distance r from the conductor is Y, , The current I is expressed by the following equation (3).
Figure JPOXMLDOC01-appb-M000001
 Since the magnetic permeability μ 0 in vacuum is μ 0 = 4π × 10 −7 , the current value I flowing through the conductor 2 is
Figure JPOXMLDOC01-appb-M000002
 Accordingly, the current value of the conductor 2 can be obtained from the distance Y (Y = r) obtained from the eddy current sensor 11 and the magnetic field strength (X) obtained from the Hall element sensor 12.
　以上の演算は、理論的に電流値を求める方法であるが、電線の絶縁被覆や電線の太さ、あるいは場所等の特性によるバラツキを少なくするために、以下のような補正を行うとよい。
　絶縁被覆厚が異なる電線を複数種類用意して、近接センサ１１が検出する距離を補正する。そして、この電線に既知の電流を流し、実際に流れている電流と等しくなるような補正式を作成し、メモリ２７に記憶させておく。測定の都度、メモリ２７に記憶された補正式を用いて、表示される電流値を補正する。 Although the above calculation is a method of theoretically obtaining a current value, the following correction may be performed to reduce variations due to characteristics such as insulation coating of the electric wire, thickness of the electric wire, and location.
A plurality of types of wires having different insulation coating thicknesses are prepared, and the distance detected by the proximity sensor 11 is corrected. Then, a known current is caused to flow through this electric wire, and a correction formula is created so as to be equal to the actually flowing current, and is stored in the memory 27. Each time the measurement is performed, the displayed current value is corrected using the correction formula stored in the memory 27.
　次に図３を参照して、渦電流センサ１１の構成について説明する。
　渦電流センサ１１は、導体２に生ずる渦電流により、センサの検出コイルのインダクタンスが変化することを検出するものであり、渦電流センサ１１の検出コイルが発生する磁界が、導体２の外に漏れると感度が低下するため、感度の低下を防ぐための工夫が必要である。
　本実施の形態では、渦電流センサ１１の検出コイルの形状を、基板上に１０ターンの導体を形成し、長手方向が導体２の軸方向であり、短手方向が導体２の幅方向である、長方形の形状として、この検出コイルを１０層に積層したものとした。各層間は、スルーホールにより、各層間を接続した。この検出コイルの縦横は、６×３ｍｍとした。
　測定対象電線の導体２の幅方向に磁界の漏れが少なく、かつ導体２の軸方向に磁気結合が長い形状となっているので、渦電流センサ１１としての感度を向上させることができる。 Next, the configuration of the eddy current sensor 11 will be described with reference to FIG.
The eddy current sensor 11 detects that the inductance of the detection coil of the sensor changes due to the eddy current generated in the conductor 2, and the magnetic field generated by the detection coil of the eddy current sensor 11 leaks out of the conductor 2. Therefore, it is necessary to take measures to prevent the sensitivity from decreasing.
In the present embodiment, the shape of the detection coil of the eddy current sensor 11 is such that a 10-turn conductor is formed on the substrate, the longitudinal direction is the axial direction of the conductor 2, and the short direction is the width direction of the conductor 2. This detection coil was formed into a rectangular shape and laminated in ten layers. The respective layers were connected to each other by through holes. The length and width of this detection coil was 6 × 3 mm.
Since the magnetic field leakage is small in the width direction of the conductor 2 of the electric wire to be measured and the magnetic coupling is long in the axial direction of the conductor 2, the sensitivity as the eddy current sensor 11 can be improved.
　図４は、さらに渦電流センサ１１と、ホール素子センサ１２との取り付け構造を説明する模式図である。
　渦電流センサ１１は、検出コイルを多層に積層しており、検出コイルの磁束感知方向は測定対象電線の導体２の軸方向に直交している。積層された検出コイルの積層体は、センサ部１０の基板１３に取り付けられている。一方、ホール素子センサの磁束感知方向は、導体２の軸方向に平行であって、検出コイルの磁束の感知方向と直交するので、ホール素子センサの磁束感度検知方向が、基板１３に直交する方向となるように、基板１３に垂直な方向にホール素子センサ１２を載せる基板を設けて、そこにホール素子センサ１２を取り付ける構造とする。 FIG. 4 is a schematic diagram for explaining a structure for mounting the eddy current sensor 11 and the Hall element sensor 12 further.
The eddy current sensor 11 has detection coils stacked in multiple layers, and the magnetic flux sensing direction of the detection coils is orthogonal to the axial direction of the conductor 2 of the electric wire to be measured. The stacked body of the stacked detection coils is attached to the substrate 13 of the sensor unit 10. On the other hand, the magnetic flux sensing direction of the Hall element sensor is parallel to the axial direction of the conductor 2 and orthogonal to the magnetic flux sensing direction of the detection coil, so that the magnetic flux sensitivity sensing direction of the Hall element sensor is orthogonal to the substrate 13. A substrate on which the Hall element sensor 12 is mounted is provided in a direction perpendicular to the substrate 13 so that the Hall element sensor 12 is mounted thereon.
　なお、以上のように、渦電流センサの検出コイルの形状を、６×３ｍｍの長方形としたが、導体２の軸方向にその形状が偏平した楕円や菱形であってもよい。また、その積層数を１０としたが、必要に応じてその積層数は選択できる。 As described above, the shape of the detection coil of the eddy current sensor is a rectangle of 6 × 3 mm, but may be an ellipse or a rhombus whose shape is flat in the axial direction of the conductor 2. Although the number of layers is set to 10, the number of layers can be selected as needed.
　（他の実施の形態）
　渦電流センサ１１の感度は、検出コイルと測定対象電線の導体２との間の磁気結合の強さによって左右される。導体に対して検出コイルが平行、すなわち、導体に対して検出コイルが発生する磁界が垂直であるときは、もっとも感度がよい。一方、検出コイルが導体に対して傾いていた場合には、磁気結合が弱くなっているので、感度が低下する。
　このため、複数の渦電流センサ１１を設けることで測定対象電線の導体２に対して傾いていたとしても、その傾きによる不確かさを補償することができる。 (Other embodiments)
The sensitivity of the eddy current sensor 11 depends on the strength of the magnetic coupling between the detection coil and the conductor 2 of the electric wire to be measured. The highest sensitivity is obtained when the detection coil is parallel to the conductor, that is, when the magnetic field generated by the detection coil is perpendicular to the conductor. On the other hand, when the detection coil is inclined with respect to the conductor, the magnetic coupling is weakened, and the sensitivity is reduced.
For this reason, by providing a plurality of eddy current sensors 11, even if the conductor is inclined with respect to the conductor 2 of the electric wire to be measured, the uncertainty due to the inclination can be compensated.
　なお、渦電流センサ１１と測定対象電線とが傾きを生ずることなく、接することができるように、電流センサ１０の測定対象電線との接触面を形成してもよい。測定対象電線に当てる面を軸方向に溝をもった形状としてもよい。
　上記実施の形態では、磁気センサとして、ホール素子センサを用いる例で説明したが、磁気センサとして、インダクタンスを用いたものでもよい。 The contact surface of the current sensor 10 with the electric wire to be measured may be formed so that the eddy current sensor 11 and the electric wire to be measured can be in contact with each other without tilting. The surface to be contacted with the electric wire to be measured may have a shape having grooves in the axial direction.
In the above-described embodiment, an example has been described in which a Hall element sensor is used as the magnetic sensor, but a magnetic sensor using an inductance may be used.
　２　　導体
　１０　　センサ部
　１１　　渦電流センサ
　１２　　ホール素子センサ
　１３　　基板
　２０　　測定装置本体
　２３、２４　アナログディジタル変換器
　２６　　ＣＰＵ
　２７　　メモリ
　２８　　インタフェース（Ｉ／Ｏ）
　３１　　操作部
　３２　　通信部
　３３　　表示部（ＬＣＤ）
　３４　　音響出力部 2 Conductor 10 Sensor Unit 11 Eddy Current Sensor 12 Hall Element Sensor 13 Substrate 20 Measuring Device Main Body 23, 24 Analog / Digital Converter 26 CPU
27 Memory 28 Interface (I / O)
31 operation unit 32 communication unit 33 display unit (LCD)
34 Sound output unit

Claims (3)

  1. 　測定対象電線の導体への距離の情報を取得する近接センサと、
    　前記測定対象電線に流れる電流によって生ずる磁界の情報を取得する磁気センサと
    　を備え、
    　前記磁気センサで取得した磁界の情報と、前記近接センサが取得した前記測定対象電線の導体への距離の情報とから、前記測定対象電線に流れる電流値を演算する演算処理部を備えている
    　ことを特徴とする電流測定装置。     A proximity sensor that acquires information on the distance of the electric wire to be measured to the conductor,
    A magnetic sensor that acquires information on a magnetic field generated by a current flowing through the electric wire to be measured,
    An arithmetic processing unit that calculates a current value flowing through the electric wire to be measured from information on a magnetic field acquired by the magnetic sensor and information on a distance to the conductor of the electric wire to be measured acquired by the proximity sensor. A current measuring device characterized by the above-mentioned.
  2. 　請求項１に記載の電流測定装置であって、
    　前記近接センサは、渦電流センサであり、
    　渦電流センサのコイルの平面形状が前記測定対象電線の伸長方向にそのコイルの長手方向が伸長した形状であって、複数枚のコイルを積層して構成されている
    　ことを特徴とする電流測定装置。     The current measuring device according to claim 1,
    The proximity sensor is an eddy current sensor,
    A current measuring device, wherein a planar shape of a coil of the eddy current sensor is a shape in which a longitudinal direction of the coil extends in a direction in which the electric wire to be measured extends, and a plurality of coils are stacked. .
  3. 　磁気センサが測定対象電線に流れる電流により生ずる磁界の情報を取得し、
    　渦電流センサが前記測定対象電線の導体への距離の情報を取得し、
    　演算処理部が、前記取得した磁界の情報と、前記測定対象電線の導体への距離の情報とから、前記測定対象電線に流れる電流の値を演算する
    　ことを特徴とする電流測定方法。     The magnetic sensor acquires information on the magnetic field generated by the current flowing through the electric wire to be measured,
    Eddy current sensor acquires information on the distance to the conductor of the electric wire to be measured,
    A current measurement method, wherein an arithmetic processing unit calculates a value of a current flowing through the electric wire to be measured from information of the acquired magnetic field and information of a distance of the electric wire to be measured to a conductor.
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