WO2023176739A1 - 電流センサ及び電線診断システム - Google Patents

電流センサ及び電線診断システム Download PDF

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Publication number
WO2023176739A1
WO2023176739A1 PCT/JP2023/009393 JP2023009393W WO2023176739A1 WO 2023176739 A1 WO2023176739 A1 WO 2023176739A1 JP 2023009393 W JP2023009393 W JP 2023009393W WO 2023176739 A1 WO2023176739 A1 WO 2023176739A1
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Prior art keywords
current sensor
bias magnet
magnetostrictive member
electric wire
magnetic field
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PCT/JP2023/009393
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English (en)
French (fr)
Japanese (ja)
Inventor
泰行 岡田
佳正 渡邊
甚 井上
武史 武舎
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Priority to JP2023556558A priority Critical patent/JP7450827B2/ja
Publication of WO2023176739A1 publication Critical patent/WO2023176739A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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

Definitions

  • the present disclosure relates to a current sensor and a wire diagnostic system.
  • abnormalities in electric wires are monitored using electrical information such as the amount of current, voltage, or phase.
  • Abnormality monitoring uses measurement data obtained from equipment such as ammeters or voltmeters installed on power distribution boards such as substations, and determines whether the data is healthy or healthy based on comparison with predetermined thresholds or signal changes. An abnormality has been determined. If an abnormality occurs, in addition to measurements using these permanently installed devices, inspectors may also go to the wire and inspect the wire.
  • Patent Document 1 Current sensors that can be easily installed on electric wires and do not require a power source for operation have been proposed (for example, see Patent Document 1).
  • Conventional technology uses a sensor that utilizes the magnetostrictive effect, which is deformation caused by a magnetic field, and the piezoelectric effect, which generates voltage due to deformation, so that a voltage is generated in accordance with the current in the wire.
  • the electromagnetic conversion effect that converts a current magnetic field into voltage is determined by the combination of a piezoelectric member and a magnetostrictive member, and when trying to apply a conventional current sensor to wires with different rated currents, the current sensor components such as material selection and shape may be affected. needs to be changed each time. As a result, it is necessary to provide a lineup of many types of current sensors depending on the current value to be measured, and there is a concern that the cost of the current sensor will increase.
  • one or more aspects of the present disclosure aim to provide a current sensor that can arbitrarily vary the input/output characteristics of the current sensor that includes a magnetostrictive member and a piezoelectric member.
  • a current sensor is a current sensor that detects a current flowing through an electric wire, and includes a piezoelectric member that is formed in a plate shape and generates a voltage by deformation in the thickness direction; , an electromagnetic transducer comprising: a magnetostrictive member disposed along the length of the piezoelectric member and deforming the piezoelectric member in the thickness direction by expanding and contracting in the length direction by a magnetic field; and a bias magnet that applies a magnetic field to the electromagnetic transducer, and the strength of the magnetic field applied from the bias magnet to the electromagnetic transducer is changed in accordance with the rated current of the electric wire.
  • a current sensor that can arbitrarily vary the input/output characteristics of the current sensor made of a magnetostrictive member and a piezoelectric member.
  • FIG. 1 is a cross-sectional view schematically showing the configuration of a current sensor according to Embodiment 1.
  • FIG. FIG. 3 is a cross-sectional view showing the expansion and contraction directions of the first magnetostrictive member and the second magnetostrictive member and the polarization direction of the piezoelectric member in the first embodiment.
  • (A) and (B) are schematic diagrams for explaining how the electromagnetic conversion element is deformed. It is a graph showing changes in magnetic flux density, which is an index of excitation strength, according to the distance from the magnet surface.
  • FIG. 3 is a schematic diagram for explaining the magnetization direction of a bias magnet and the distance from the surface of the bias magnet.
  • FIG. 3 is a perspective view showing an example of a case where the number of layers of bias magnets is changed in the magnetization direction of the bias magnets.
  • (A) to (C) are graphs showing the output of the current sensor when the number of bias magnets is changed. It is a graph showing the dependence of the output of a current sensor on the number of magnets with respect to a constant current.
  • FIG. 3 is a cross-sectional view schematically showing the configuration of a current sensor according to a second embodiment.
  • (A) and (B) are cross-sectional views showing a housing and a modification of the housing.
  • FIG. 2 is a cross-sectional view schematically showing the configuration of an element-containing section.
  • (A) and (B) are cross-sectional views showing an example in which a plurality of electromagnetic conversion elements are arranged in one element built-in part.
  • (A) and (B) are cross-sectional views schematically showing the configuration of a modified example of the current sensor according to the second embodiment. It is a graph showing the relationship between the current flowing in the electric wire and the output of the current sensor.
  • FIG. 7 is a cross-sectional view schematically showing the configuration of a current sensor according to Embodiment 3.
  • FIG. 7 is a cross-sectional view schematically showing the configuration of a current sensor according to Embodiment 4.
  • FIG. 3 is a schematic diagram for explaining deformation of an electromagnetic transducer by a bias magnet.
  • FIG. 7 is a cross-sectional view showing the expansion/contraction direction of the first magnetostrictive member and the second magnetostrictive member and the polarization direction of the piezoelectric member in Embodiment 4.
  • FIG. (A) and (B) are schematic diagrams for explaining how the electromagnetic conversion element is deformed in Embodiment 4.
  • FIG. 7 is a cross-sectional view schematically showing the configuration of a current sensor according to Embodiment 5.
  • 7 is a cross-sectional view showing the flow of magnetic lines of force in a current sensor according to Embodiment 5.
  • FIG. 1 is a cross-sectional view schematically showing the configuration of a current sensor 100 according to the first embodiment.
  • Current sensor 100 includes an electromagnetic conversion element 110 and a bias magnet 120.
  • the electromagnetic transducer 110 includes a first magnetostrictive member 111A, a second magnetostrictive member 111B, and a piezoelectric member 112.
  • the first magnetostrictive member 111A and the second magnetostrictive member 111B are made of a magnetostrictive material that is deformed by applying a magnetic field.
  • an alloy consisting of iron (Fe), dysprosium (Dy), and terbium (Tb) called Terfenol-D is used as the magnetostrictive material.
  • the first magnetostrictive member 111A and the second magnetostrictive member 111B are formed in a plate shape, and expand and contract in the longitudinal direction by a magnetic field.
  • the piezoelectric member 112 is made of a piezoelectric material that has a voltage effect, which is a phenomenon in which polarization proportional to pressure appears when pressure is applied to a substance.
  • the generally known lead zirconate titanate (PZT) is used as the piezoelectric material.
  • the piezoelectric member 112 is formed into a plate shape, generates a voltage by deformation in the thickness direction, and is disposed between the first magnetostrictive member 111A and the second magnetostrictive member 111B.
  • the first magnetostrictive member 111A, the second magnetostrictive member 111B, and the piezoelectric member 112 each have a thickness of 1.0 mm in the vertical direction in FIG. 1, and a width of 6 mm in the depth direction in FIG.
  • the length of the first magnetostrictive member 111A and the second magnetostrictive member 111B is 12 mm, and the length of the piezoelectric member 112 is 15 mm.
  • the reason why the piezoelectric member 112 is longer than the first magnetostrictive member 111A and the second magnetostrictive member 111B is to provide the electrode 102 to which the lead wires 101A and 101B are soldered to take out the voltage generated in the piezoelectric member 112. be.
  • the first magnetostrictive member 111A, the second magnetostrictive member 111B, and the piezoelectric member 112 are bonded with silver paste.
  • the magnetostrictive material and the piezoelectric material are not limited to the above materials, and other materials may be used. Also, the dimensions of these members may be other dimensions.
  • Bias magnet 120 provides a magnetic field to electromagnetic conversion element 110.
  • an NdFeB magnet which is a rare earth magnet, is used as the bias magnet 120.
  • NdFeB magnets are magnets whose main components are neodymium (Nd), iron (Fe), and boron (B).
  • the dimensions of the bias magnet 120 are 4 mm x 4 mm x 2 mm, and the dimension in the magnetization direction shown in FIG. 1 is 2 mm.
  • the bias magnet 120 applies a magnetic field to the electromagnetic transducer 110 in the longitudinal direction of the first magnetostrictive member 111A and the second magnetostrictive member 111B.
  • the current sensor 100 in the first embodiment changes the magnitude of the voltage generated in the piezoelectric member 112 included in the electromagnetic transducer 110 by changing the strength of the magnetic field applied from the bias magnet 120 to the electromagnetic transducer 110. change the value.
  • the current sensor 100 then changes the strength of the magnetic field applied from the bias magnet 120 to the electromagnetic conversion element 110 in accordance with the rated current of the electric wire 103.
  • the bias magnet 120 is arranged to face one end b in the longitudinal direction of the electromagnetic transducer 110 so that the magnetization direction is parallel to the longitudinal direction of the electromagnetic transducer 110.
  • an electromagnet other than the bias magnet can be used as the excitation source, but in this case, a bias magnet that does not require a power source for excitation is used.
  • the current sensor 100 configured as described above is arranged in a direction perpendicular to the longitudinal direction of the electric wire 103 to be measured.
  • the current sensor 100 is arranged so that the longitudinal direction of the electromagnetic transducer 110 or the magnetization direction of the bias magnet 120 is orthogonal to the electric wire 103.
  • the magnetic field created by the electric wire 103 is equal to the circumferential direction (in other words, the tangential direction) of the cross section of the electric wire 103, and decreases in the normal direction. Therefore, by arranging the current sensor 100 at a predetermined distance away from the electric wire 103 so that the tangential direction of the electric wire 103 is parallel to the longitudinal direction of the current sensor 100, the electromotive force caused by the current can be efficiently reduced. You can get a good deal.
  • FIG. 2 is a cross-sectional view showing the expansion and contraction directions of the first magnetostrictive member 111A and the second magnetostrictive member 111B, and the polarization direction of the piezoelectric member 112.
  • the direction of expansion and contraction when a magnetic field is applied to the first magnetostrictive member 111A and the second magnetostrictive member 111B is set in the left-right direction in FIG. 2, and the polarization direction of the piezoelectric member 112 is , are set in the vertical direction of FIG.
  • the directions of expansion and contraction of the first magnetostrictive member 111A and the second magnetostrictive member 111B are set to be opposite to each other with respect to changes in the magnetic field.
  • the directions of expansion and contraction are opposite to each other means, for example, when the first magnetostrictive member 111A shown in FIG. 2 has a characteristic that it extends as the magnetic field applied to the left in FIG. 111B means a characteristic that increases as the magnetic field applied to the right in FIG. 2 increases.
  • the electric wires 103#1 and 103#2 are arranged below the electromagnetic transducer 110, and When a current flows through 2, the electromagnetic conversion element 110 deforms to become convex downward or convex upward depending on the direction of the current.
  • a current flows in the depth direction of FIG. 3(A) a rightward magnetic field is applied to the entire electromagnetic conversion element 110, and the first magnetostrictive member 111A contracts.
  • the electromagnetic transducer 110 deforms to become convex downward.
  • FIG. 3(B) as the current flows toward the front in FIG.
  • a leftward magnetic field is applied to the entire electromagnetic transducer 110, the first magnetostrictive member 111A extends, and the second magnetostrictive member By shrinking 111B, the electromagnetic transducer 110 deforms to become convex upward.
  • FIG. 4 is a graph showing changes in magnetic flux density, which is an index of excitation strength, depending on the distance from the magnet surface. As shown in FIG. 5, the distance from the magnet surface is, as shown in FIG. This is the distance to one end 110a.
  • a curve C1 shown in FIG. 4 indicates the magnetic flux density when the center of the electromagnetic transducer 110 is aligned with the center 120b of the magnet surface 120a, as shown in FIG.
  • a curve C2 shown in FIG. 4 shows the magnetic flux density when the center of the electromagnetic transducer 110 is located above the center 120b of the magnet surface 120a in the thickness direction, as shown in FIG. .
  • a curve C3 shown in FIG. 4 shows the magnetic flux density when the center of the electromagnetic transducer 110 is located further above the center 120b of the magnet surface 120a, as shown in FIG.
  • the magnetic flux density decreases in inverse proportion to the square of the excitation source, and also decreases outward (here, upward) from the center 120b of the magnet surface 120a. Therefore, by changing the distance between the electromagnetic transducer 110 and the bias magnet 120, or by shifting the position where the bias magnet 120 faces the electromagnetic transducer 110 up and down, the strength of the magnetic field applied to the electromagnetic transducer 110 can be changed. can be done.
  • FIG. 6 is a graph showing an example of the output when the position of the bias magnet 120 relative to the electromagnetic transducer 110 is changed in the vertical direction. Although an alternating current is flowing through the electric wire 103 here, it is clear from the operating principle of the electromagnetic conversion element 110 that a similar output can be obtained with a direct current.
  • FIG. 7(A) the straight line L1 shown in FIG. The output when combined is shown.
  • FIG. 7(B) the straight line L2 shown in FIG. The output is shown when is above.
  • the output from the electromagnetic transducer 110 is proportional to the amount of deformation of the electromagnetic transducer 110, and the magnitude of the magnetic field that causes the deformation of the electromagnetic transducer 110 increases in proportion to the current value. Therefore, as shown in FIG. 6, the sensor output, which is the output of the current sensor 100, changes linearly according to the current value.
  • the electromagnetic transducer is If the element 110 is arranged offset above the center in the thickness direction, the output of the current sensor 100 is reduced.
  • the output of the current sensor 100 also changes depending on the magnitude of the magnetic field applied to the electromagnetic transducer 110. It is clear that although not shown, the output of the current sensor 100 is also reduced by increasing the facing distance between the bias magnet 120 and the electromagnetic conversion element 110.
  • FIG. 8 is a graph showing changes in magnetic flux density from the surface of the bias magnet 120 (the surface through which the magnetization direction of the magnet passes) when the number of bias magnets 120 of the same size is changed by changing the number of stacked magnets. It is. The case where there is only one bias magnet 120 corresponds to curve C3 shown in FIG. 4.
  • the number of layers of bias magnets 120 is changed in the magnetization direction of bias magnets 120.
  • the magnetic flux density As shown in FIG. 8, there is a tendency for the magnetic flux density to increase as the number of bias magnets 120 increases, but the rate of increase does not match the increase in number. For example, as shown in FIG. 8, there is no significant difference between increasing the number of bias magnets 120 to two and increasing the number of bias magnets 120 to three. Moreover, the magnetic flux density is almost the same between the case where there are three bias magnets 120 and the case where there are four bias magnets 120. This suggests that stacking the bias magnets 120 to increase the excitation magnetic field is not very effective.
  • FIGS. 10A to 10C are graphs showing the output of the current sensor 100 when the number of bias magnets 120 is changed.
  • FIG. 10(A) is a graph when the number of bias magnets 120 is one
  • FIG. 10(B) is a graph when there are two bias magnets 120
  • FIG. 10(C) is a graph when the number of bias magnets 120 is two. This is a graph when there are three bias magnets 120.
  • FIG. 11 is a graph showing the dependence of the output of the current sensor 100 on the number of magnets with respect to a constant current (here, 90 A).
  • the output of the current sensor 100 does not monotonically increase.
  • the output is saturated.
  • the number of bias magnets 120 is changed here, for example, even if the thickness of the bias magnets 120 is increased by a constant thickness (for example, 2 mm), the number of bias magnets 120 facing the electromagnetic transducer 110 may be increased. It is known that the magnetic flux density distribution from the surface of .
  • the increasing tendency of the output of the current sensor 100 with respect to the thickness of the bias magnet 120 is also similar to that shown in FIG. It is obvious that it can be done.
  • the point at which the output of the current sensor 100 is saturated is determined by the dimension of the bias magnet 120 in the magnetization direction and the dimension of the electromagnetic transducer 110 in the longitudinal direction.
  • the output of the current sensor 100 is approximately proportional to the magnetic flux density from the surface of the bias magnet 120, the output of the current sensor 100 can be increased or decreased depending on the magnitude of the excitation magnetic field.
  • the output of current sensor 100 can be changed.
  • FIG. 12 is a cross-sectional view schematically showing the configuration of a current sensor 200 according to the second embodiment.
  • Current sensor 200 includes an electromagnetic conversion element 110, a bias magnet 120, and a housing 230.
  • the electromagnetic transducer 110 and bias magnet 120 of the current sensor 200 according to the second embodiment are the same as the electromagnetic transducer 110 and the bias magnet 120 of the current sensor 100 according to the first embodiment. Therefore, the electromagnetic transducer 110 includes a first magnetostrictive member 111A, a second magnetostrictive member 111B, and a piezoelectric member 112.
  • the housing 230 includes an element built-in part 231 that houses the electromagnetic transducer 110 and a bias magnet 120 that excites the electromagnetic transducer 110, and a conductor grip part 232 that grips the electric wire 103 to be measured.
  • FIGS. 13A and 13B are cross-sectional views showing a housing 230 and a modification of the housing 230.
  • the magnetic flux density decreases in proportion to the square of the distance from the magnetic field generation source. Therefore, in order to obtain as large an output as possible from the current sensor 200, the electric wire 103 and the electromagnetic conversion element 110 must be It is desirable to have them as close as possible.
  • the conductor grip part 232 of the housing 230 is fitted into the element built-in part 231 and fixed.
  • the magnetostrictive members 111A and 111B contain a large amount of iron, there is a concern that their performance may deteriorate due to rusting or the like due to long-term exposure to the atmosphere. Therefore, in order to ensure weather resistance, at least the electromagnetic conversion element 110 among the components of the current sensor 200 needs to be covered with a weather resistant material such as resin. As mentioned above, in order to bring the current sensor and the electric wire as close as possible, it is desirable to make the coating resin as thin as possible while still ensuring weather resistance.
  • the conductor gripping portion 232 includes bonding surfaces 232a1 and 232a2, inner wall surfaces 232b1 and 232b2, and pressing surfaces 232c1 and 232c2 extending from each of the inner wall surfaces 232b1 and 232b2 toward the other.
  • the joint surfaces 232a1 and 232a2 are provided with fitting members (not shown) for fitting into the element built-in part 231, and when the conductor grip part 232 is fitted into the element built-in part 231, It is a contact surface.
  • the inner wall surfaces 232b1 and 232b2 are surfaces extending toward the inside of the conductor gripping portion 232 from the joint surfaces 232a1 and 232a2, respectively.
  • the inner wall surfaces 232b1 and 232b2 are substantially perpendicular to the joint surfaces 232a1 and 232a2, and the distance D1 between the inner wall surfaces 232b1 and 232b2 is equal to or larger than the diameter D2 of the electric wire 103 shown in FIG. It is assumed that there is
  • the pressing surfaces 232c1 and 232c2 are surfaces extending from each of the inner wall surfaces 232b1 and 232b2 toward the other.
  • the pressing surface 232c1 is a surface extending from the inner wall surface 232b1 to the inner wall surface 232b2
  • the pressing surface 232c2 is a surface extending from the inner wall surface 232b2 to the inner wall surface 232b1.
  • the holding surfaces 232c1 and 232c2 are joined to each other in the middle of the distance D1 between the inner wall surfaces 232b1 and 232b, and the angle R between the holding surfaces 232c1 and 232c2 is larger than 0 degrees and smaller than 180 degrees. It is composed of The holding surfaces 232c1 and 232c2 are configured to come into contact with the electric wire 103 when the conductor gripping portion 232 is fitted into the element built-in portion 231. With this configuration, when the conductor gripping part 232 is fitted into the element built-in part 231, the holding surfaces 232c1 and 232c2 hold the electric wire 103 in the element so that the holding surfaces 232c1 and 232c2 bring the electric wire 103 close to the element built-in part 231. Since it is pushed in the direction of the portion 231, the electromagnetic conversion element 110 and the electric wire 103 come close to each other.
  • the angle R between the pressing surfaces 232c1 and 232c2 is larger than 0 degrees and smaller than 180 degrees. This is to reduce the deviation in the width direction of the electric wire 103 with respect to the longitudinal direction of the electromagnetic conversion element 110, and also to reduce such deviation regardless of the diameter of the electric wire 103. .
  • the longitudinal direction of the electromagnetic transducer 110 and the width direction of the electric wire 103 are the left-right direction in FIG. 13(A).
  • the inner wall surfaces 232b1 and 232b2 may be connected to each other by a semicircular arc-shaped pressing surface 232c#1, as shown in FIG. 13(B).
  • the pressing surface 232c#1 may be formed so as to be in contact with the outer circumferential surface of the electric wire 103.
  • the shape of the conductor gripping part 232 may be other than the above example.
  • the conductor grip part 232 functions as a fixing member for attaching the element built-in part 231 serving as a cover to the electric wire 103 so that the longitudinal direction of the electromagnetic conversion element 110 is orthogonal to the longitudinal direction of the electric wire 103. .
  • the element built-in portion 231 functions as a cover that covers the electromagnetic conversion element 110 and the bias magnet 120.
  • FIG. 14 is a cross-sectional view schematically showing the structure of the element built-in portion 231.
  • the element built-in portion 231 holds the bias magnet 120 and the electromagnetic conversion element 110 therein. In other words, the element built-in portion 231 surrounds the bias magnet 120 and the electromagnetic conversion element 110.
  • the element built-in portion 231 includes a partition wall 231a for separating the bias magnet 120 and the electromagnetic conversion element 110 by an arbitrary dimension.
  • a resin material may be used from the viewpoint of ensuring electrical insulation, and a magnetic material such as a silicon steel plate or a high magnetic permeability material may be used to control the excitation magnetic field from the bias magnet 120. It's okay to be hit.
  • the bias magnet 120 and the electromagnetic transducer 110 may be brought into contact without providing the partition 231a. You may let them. However, since the electromagnetic transducer 110 generates an electromotive force due to its deformation, it is preferable that the bias magnet 120 not be brought into contact with the electromagnetic transducer 110 from the viewpoint of not hindering the deformation of the electromagnetic transducer 110.
  • a gap is provided between the bias magnet 120, the partition wall 231a, and the electromagnetic transducer 110 in order to clearly show each, but since the magnetostrictive members 111A and 111B contain a large amount of iron, the bias magnet 120 is attracted by magnetic force. Therefore, no gap actually exists, the bias magnet 120 is in contact with the partition wall 231a, and the electromagnetic transducer element 110 is also in contact with the partition wall 231a. In this way, the electromagnetic transducer 110 is fixed to the partition wall 231a by the magnetic force of the bias magnet 120, so a mechanism for fixing the electromagnetic transducer 110 to the element built-in part 231 is unnecessary, and the electromagnetic transducer 110 is restrained as much as possible. Therefore, it becomes possible to extract the maximum amount of electromotive force.
  • FIGS. 15A and 15B are cross-sectional views showing an example in which a plurality of electromagnetic conversion elements 110 are arranged in one element built-in part 231.
  • a plurality of bias magnets 120 may be provided to correspond to each of the plurality of electromagnetic conversion elements 110.
  • one bias magnet 120 may be provided for a plurality of electromagnetic conversion elements 110. Since one bias magnet 120 has a width corresponding to the width of the electromagnetic transducers 110 arranged in parallel, it becomes possible to excite all the electromagnetic transducers 110 with that one bias magnet 120. . With this configuration, the number of parts can be reduced and the cost of the current sensor 200 can be reduced.
  • FIGS. 16A and 16B are cross-sectional views showing a modification of the current sensor 200 according to the second embodiment.
  • the current sensor 200#2 according to the first modified example of the second embodiment is mounted not on the element built-in portion 231#2 side of the housing 230#2, but on the conductor gripping side.
  • the electromagnetic conversion element 110 and the bias magnet 120 are built into the portion 232#2 side.
  • the electromagnetic transducer 110 and the bias magnet 120 be arranged along the pressing surface 232c1#2 of the conductor gripping part 232#2, as shown in FIG. 16(A).
  • the positional relationship between the electric wire 103 and the electromagnetic conversion element 110 can be uniquely determined by the structure of the housing 230#2.
  • the electromagnetic transducer 110 and the bias magnet 120 are arranged along both the holding surface 232c1#3 and the holding surface 232c2#3. Good too.
  • Embodiment 3 The current sensors 100, 200 according to the first or second embodiment do not require a power source to drive the current sensors 100, 200, and can obtain an electromotive force by using the current magnetic field of the electric wire 103 to be measured. .
  • FIG. 10(C) when three bias magnets 120 are placed facing the electromagnetic transducer 110 and a current of 90 A is applied, an output of about 2.3 V is obtained. I understand that.
  • FIG. 6 or FIG. 8 it was also explained that the output of the current sensor 100 with respect to the current value exhibits excellent linearity.
  • a voltage of 3.3V can be obtained for a current of about 140A, as shown in FIG.
  • a current sensor is connected to the electric wire 103 with a current value of 140A or more.
  • the electromotive force of current sensors 100 and 200 is used to transmit current values without a power storage device. Further, even if the rated current is small, communication is possible if a current exceeding 140 A flows due to an overhead line accident or the like.
  • overcurrent is caused by an overloaded state or a ground fault due to disconnection, and overcurrent is thought to flow relatively continuously rather than for a short period of time like a sudden current.
  • the driving voltage can be secured for a period of about 20 ms to 30 ms.
  • a power storage circuit may also be used to intermittently transmit the detected rated current value.
  • FIG. 18 is a cross-sectional view schematically showing the configuration of a current sensor 300 according to the third embodiment.
  • Current sensor 300 includes an electromagnetic conversion element 110, a bias magnet 120, and a housing 330.
  • the electromagnetic transducer 110 and bias magnet 120 of the current sensor 300 according to the third embodiment are the same as the electromagnetic transducer 110 and the bias magnet 120 of the current sensor 100 according to the first embodiment. Therefore, the electromagnetic transducer 110 includes a first magnetostrictive member 111A, a second magnetostrictive member 111B, and a piezoelectric member 112.
  • the housing 330 functions as a communication unit, including an element built-in part 231 that contains the electromagnetic transducer 110 and a bias magnet 120 that excites the electromagnetic transducer 110, a conductor grip part 232 that grips the electric wire 103 to be measured.
  • the communication unit built-in section 340 has a built-in communication circuit board 341 built therein.
  • the element built-in part 231 and the conductor grip part 232 of the housing 330 in the third embodiment are the same as the element built-in part 231 and the conductor grip part 232 of the housing 230 in the second embodiment.
  • a communication unit built-in section 340 is attached to the element built-in section 231.
  • the communication unit built-in portion 340 is also desirably made of a weather-resistant material.
  • the communication unit built-in section 340 includes a communication circuit board 341 therein.
  • the communication circuit board 341 includes a communication circuit that transmits and receives data, and a power supply circuit that supplies power to the communication circuit.
  • An electromagnetic conversion element 110 is electrically connected to the power supply circuit.
  • the communication circuit board 341 may be a transmission line board that only transmits data.
  • the communication unit also becomes a transmitting unit.
  • the current sensor 300 according to the third embodiment includes a transmitting unit that is driven by the voltage generated in the piezoelectric member 112 and transmits data that can detect an abnormality in the electric wire 103.
  • the data transmitted from the communication circuit board 341 may be voltage data corresponding to the electromotive force of the electromagnetic conversion element 110 input to the communication circuit board 341, or simply tag information indicating that the communication circuit board 341 has been activated.
  • the data may be unique to the communication circuit board 341, as shown in FIG.
  • the current value detected by the current sensor 300 can be found. If the data is unique to the communication circuit board 341, it can be seen that the current sensor 300 has been activated, so it can be seen that an overcurrent sufficient to activate the communication circuit has flowed in the electric wire 103 to be measured.
  • Embodiment 3 by installing a large number of current sensors according to Embodiment 3 in a power distribution network composed of electric wires 103, it is possible to construct an electric wire diagnostic system (not shown) that issues an alarm when an overhead line accident occurs due to overcurrent. becomes possible.
  • the current sensor 300 does not require a power source to operate, and the communication microcomputer can also operate with the output of the current sensor 300, so the current sensor 300 can be placed even in places where it is difficult to secure a power source, making it possible to detect catenary accidents early. Become.
  • the electric wire diagnostic system includes a current sensor 300 and a current line diagnostic section that detects an abnormality in the electric wire based on data transmitted from the current sensor 300.
  • the wire diagnostic system includes a current sensor 300 installed on the wire 103, an external server (not shown) that receives the current value or current waveform transmitted from the current sensor 300, and an external server that receives the current value or current waveform transmitted from the current sensor 300.
  • the electric wire diagnosis section can diagnose an abnormality in the electric wire 103 based on the received current value or current waveform.
  • the wire diagnosis section may immediately diagnose abnormalities in the wire 103 from the current value or current waveform transmitted from the current sensor 300, or may diagnose the damage level of the overhead wire with the current value or current waveform stored in an external server.
  • An abnormality in the electric wire 103 may be diagnosed from a database showing the relationship between the following.
  • the electric wire diagnostic system allows the current sensor 300 to be placed even in places where it is difficult to secure a power supply, and enables early detection of overhead line accidents.
  • the wire diagnosis section may directly receive the current value or current waveform transmitted from the current value transmitting unit to diagnose abnormalities in the wire.
  • the wire diagnosis section can be realized by a so-called computer.
  • the computer includes a receiving section as a receiving device that can receive data from the current sensor 300.
  • the wire diagnosis section may be provided in an external server.
  • two magnetostrictive members the first magnetostrictive member 111A and the second magnetostrictive member 111B
  • the piezoelectric member 112 can be deformed using only one of the first magnetostrictive member 111A and the second magnetostrictive member 111B
  • polarization can be generated in the thickness direction of the piezoelectric member 112.
  • the electromagnetic transducer 110 may include only one of the first magnetostrictive member 111A and the second magnetostrictive member 111B.
  • FIG. 19 is a cross-sectional view schematically showing the configuration of a current sensor 400 according to the fourth embodiment.
  • Current sensor 400 includes an electromagnetic conversion element 110 and a bias magnet 420.
  • the electromagnetic transducer 110 of the current sensor 400 according to the fourth embodiment is similar to the electromagnetic transducer 110 of the current sensor 100 according to the first embodiment.
  • bias magnet 420 provides a magnetic field to the electromagnetic conversion element 110.
  • the material of bias magnet 420 is the same as that of bias magnet 120 of current sensor 100 according to the first embodiment.
  • Bias magnet 420 includes a first bias magnet 420A and a second bias magnet 420B. As shown in FIG. 19, the first bias magnet 420A and the second bias magnet 420B are both configured such that their magnetization directions M1 and M2 are parallel to the longitudinal direction of the electromagnetic transducer 110. However, the magnetization direction M1 of the first bias magnet 420A and the magnetization direction M2 of the second bias magnet 420B are exactly opposite. Note that the magnetization direction M1 is also referred to as a first direction, and the magnetization direction M2 is also referred to as a second direction.
  • a bias magnetic field is applied to the first magnetostrictive member 111A and the second magnetostrictive member 111B by installing the bias magnet 120 as shown in FIG.
  • the first magnetostrictive member 111A shrinks compared to the state without a magnetic field before setting.
  • the second magnetostrictive member 111B is in an extended state compared to the state without a magnetic field before setting.
  • warpage occurs in the electromagnetic transducer 110 when the bias magnet 120 and the electromagnetic transducer 110 are combined. For this reason, polarization occurs in the thickness direction of the piezoelectric member 112, and a potential difference occurs between the upper and lower electrodes, resulting in the generation of voltage.
  • the output of the current sensor 100 may be affected.
  • a rightward bias magnetic field is applied to the first magnetostrictive member 111A from the first bias magnet 420A, and a rightward bias magnetic field is applied to the second magnetostrictive member 111B from the second bias magnet.
  • a leftward bias magnetic field is applied from 420B.
  • the first magnetostrictive member 111A contracts in response to the magnetic field in the right direction
  • the second magnetostrictive member 111B contracts in response to the magnetic field in the left direction.
  • Both the magnetostrictive member 111A and the second magnetostrictive member 111B are in a more contracted state than in the no-magnetic-field state before setting. Since both the first magnetostrictive member 111A and the second magnetostrictive member 111B contract, no warpage occurs in the electromagnetic transducer element 110.
  • the magnetic field caused by the current applies a magnetic field of C[T] to the electromagnetic transducer 110 in a rightward direction.
  • the first magnetostrictive member 111A further contracts from the state where the bias magnetic field is applied, and the second magnetostrictive member 111A
  • the member 111B extends from the state where the bias magnetic field is applied. Therefore, as the current flows, a downward convex warpage occurs, the piezoelectric member 112 is deformed, and the voltage changes.
  • the sensitivity can be adjusted by changing the distance or relative vertical position between the bias magnet 420 and the electromagnetic transducer 110, and the number of bias magnets 420.
  • bias magnet 420 described in the fourth embodiment may be used instead of the bias magnet 120 described in the second or third embodiment.
  • FIG. 23 is a cross-sectional view schematically showing the configuration of a current sensor 500 according to the fifth embodiment.
  • Current sensor 500 includes an electromagnetic conversion element 510 and a bias magnet 420.
  • Bias magnet 420 of current sensor 500 according to Embodiment 4 is similar to bias magnet 420 of current sensor 400 according to Embodiment 4. Therefore, the bias magnet 420 includes a first bias magnet 420A and a second bias magnet 420B, and the magnetization direction M1 of the first bias magnet 420A and the magnetization direction M2 of the second bias magnet 420B are as follows. It's the exact opposite.
  • the electromagnetic transducer 510 in the fifth embodiment includes a first magnetostrictive member 111A, a second magnetostrictive member 111B, a piezoelectric member 112, and a magnetic yoke 513.
  • the first magnetostrictive member 111A, the second magnetostrictive member 111B, and the piezoelectric member 112 of the electromagnetic transducer 510 in the fifth embodiment are the same as the first magnetostrictive member 111A, the second magnetostrictive member 112 of the electromagnetic transducer 110 in the first embodiment. This is the same as the member 111B and the piezoelectric member 112.
  • the magnetic yoke 513 is disposed on the opposite side of the bias magnet 420 in the longitudinal direction of the electromagnetic conversion element 510.
  • the magnetic yoke 513 is a U-shaped member including a first portion 513a, a second portion 513b, and a third portion 513c.
  • the first portion 513a is a plate-shaped portion that extends in a direction parallel to the longitudinal direction of the first magnetostrictive member 111A and faces the first magnetostrictive member 111A.
  • the second portion 513b is a plate-shaped portion that extends in a direction parallel to the longitudinal direction of the second magnetostrictive member 111B and faces the second magnetostrictive member 111B.
  • the third portion 513c is a portion that connects the first portion 513a and the second portion 513b on the side opposite to the first magnetostrictive member 111A and the second magnetostrictive member 111B.
  • the reason why the magnetic yoke 513 is formed in a U-shape is to avoid contact with the electrode 102 and the lead wires 101A and 101B from the electrode 102.
  • the shape of the magnetic yoke 513 is not particularly limited as long as it can achieve this purpose.
  • the electromagnetic conversion element 510 described in the fifth embodiment may be used instead of the electromagnetic conversion element 110 described in the second or third embodiment.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
PCT/JP2023/009393 2022-03-16 2023-03-10 電流センサ及び電線診断システム Ceased WO2023176739A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6809516B1 (en) * 1999-04-05 2004-10-26 Spinix Corporation Passive magnetic field sensors having magnetostrictive and piezoelectric materials
JP2012037508A (ja) * 2010-07-12 2012-02-23 Sumida Corporation 電流センサ
JP2021081240A (ja) * 2019-11-15 2021-05-27 株式会社ダイヘン 電気信号検出装置
CN112881781A (zh) * 2021-01-20 2021-06-01 西南交通大学 一种无源雷电流传感器

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6809516B1 (en) * 1999-04-05 2004-10-26 Spinix Corporation Passive magnetic field sensors having magnetostrictive and piezoelectric materials
JP2012037508A (ja) * 2010-07-12 2012-02-23 Sumida Corporation 電流センサ
JP2021081240A (ja) * 2019-11-15 2021-05-27 株式会社ダイヘン 電気信号検出装置
CN112881781A (zh) * 2021-01-20 2021-06-01 西南交通大学 一种无源雷电流传感器

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