JP7475783B2 - Conductor Deterioration Detection Device - Google Patents

Description

The present invention relates to a conductor deterioration detection device.

Conventionally, insulated electric wires (hereinafter simply referred to as "electric wires") laid on utility poles can corrode the copper conductor inside due to the infiltration of water from the outside, affecting the power transmission capacity. In order to perform maintenance and management of the electric wires, it is necessary to know whether or not the copper conductor is corroded, and the extent of the corrosion, before it affects the power transmission capacity. Meanwhile, a conductor deterioration detection device using eddy current testing is known as a device for non-destructively detecting corrosion of copper conductors (see, for example, Patent Document 1). The conductor deterioration detection device has an excitation coil and a detection coil, and applies an AC voltage to the excitation coil to generate a magnetic flux, thereby generating an eddy current in the copper conductor, and detects the flaws in the electric wire from the detection value of the detection coil based on the magnetic flux of the eddy current.

When inspecting electric wires installed on utility poles using a conductor deterioration detection device, in order to reduce the risk of an operator climbing to a high place, attaching the device to the electric wire, and moving it in the direction in which the electric wire extends, a detection device in which, for example, a clamp unit and a detection unit are integrated is used (see, for example, Patent Document 2).

JP 2018-132469 A JP 2015-186430 A

However, in the above-mentioned conductor deterioration detection device, for example, if the electric wire held by the clamping portion is displaced in the width direction of the electric wire with respect to the detection position corresponding to the position of the central axis of the detection coil, the output value of the detection coil may decrease, which may affect the detection accuracy. In particular, when inspecting multiple types of electric wires with different outer diameters, there is room for improvement because the central axis of the electric wire held by the clamping portion may be displaced in the width direction due to differences in the outer diameters of the electric wires.

The present invention aims to provide a conductor deterioration detection device that can suppress the shift in the width direction caused by differences in the outer diameter of the electric wire held by the holding mechanism and suppress the decrease in detection accuracy.

In order to achieve the above object, a conductor deterioration detection device according to the present invention comprises an excitation coil which generates an eddy current in an object to be measured having a circular cross-sectional shape , a detection coil which detects magnetic flux due to the eddy current generated in the object to be measured, and a housing which accommodates the excitation coil and the detection coil, the housing having an inspection base which is formed of a non-magnetic material and has a contact surface which comes into contact at a first contact with a plurality of types of objects to be measured having different outer diameters, and a holding mechanism which holds the object to be measured between the inspection base in a contact state in which the object to be measured is in contact with the inspection base, the holding mechanism being formed to be rotatable about a rotation axis, and in a holding state in which the object to be measured is held by the holding mechanism, a first arm portion which comes into contact with an outer peripheral surface of the object to be measured at a second contact and a third contact, and a holding position in the holding state and a release position for the object to be measured from the holding state. and a second arm portion that rotates the first arm portion in the rotation direction of the rotation axis by an external force between an open position where the first arm portion is rotated and an open position where the second arm portion is rotated and held such that, in the held state, the outer peripheral surface of the object to be measured, which is arranged so that the central axis of the object to be measured and the central axis of the detection coil are perpendicular to each other, and the contact surface of the inspection base is in contact with the first contact point, and when viewed in the axial direction of the rotation axis in the held state, the first contact point is located on a virtual line that passes through the central axis of the detection coil, is perpendicular to the contact surface of the inspection base and passes through the central axis of the object to be measured, the second contact point is located on the rotation axis side of the virtual line that passes through the first contact and the central axis of the object to be measured, when viewed in the axial direction of the rotation axis in the held state, and the third contact point is located on the opposite side of the rotation axis across the virtual line, when viewed in the axial direction of the rotation axis in the held state.

In order to achieve the above object, a conductor deterioration detection device according to the present invention comprises an excitation coil that generates an eddy current in an object to be measured having a circular cross-sectional shape , a detection coil that detects magnetic flux due to the eddy current generated in the object to be measured, and a housing that accommodates the excitation coil and the detection coil, the housing having an inspection base formed of a non-magnetic material and having a contact surface that comes into contact at a first contact with a plurality of types of objects to be measured having different outer diameters, and a holding mechanism that holds the object to be measured between the inspection base and the inspection base in a contact state in which the object to be measured is in contact with the inspection base, the holding mechanism being formed to be rotatable about a rotation axis, and having a first arm portion that contacts an outer peripheral surface of the object to be measured at a second contact point and a third contact point in a holding state in which the object to be measured is held by the holding mechanism, and a second arm portion that rotates the first arm portion in a rotation direction of the rotation axis by an external force between a holding position in the holding state and an release position in which the object to be measured is released from the holding state, and in the holding state , the first contact is disposed on a virtual line that passes through the central axis of the detection coil, is perpendicular to the contact surface of the inspection base, and passes through the central axis of the object to be measured when viewed from the axial direction of the rotation shaft in the held state; the second contact is disposed on the rotation axis side of the virtual line that passes through the first contact and the central axis of the object to be measured when viewed from the axial direction of the rotation shaft in the held state; and the third contact is disposed on the opposite side to the rotation axis across the virtual line when viewed from the axial direction of the rotation shaft in the held state; and a distance between the contact surface on the inspection base and the rotation axis in a vertical direction perpendicular to the axial direction is shorter than a distance in the vertical direction between the contact surface of the inspection base and the central axis of the large diameter electric wire when a large diameter electric wire having the largest outer diameter of the objects to be measured is held by the holding mechanism.

Furthermore, in the above-mentioned conductor deterioration detection device, the first arm portion has a first holding surface having the second contact point, and a second holding surface having the third contact point and located farther from the rotation axis than the first holding surface when viewed in the axial direction of the rotation axis, wherein the first holding surface has a linear cross-sectional shape when viewed in the axial direction of the rotation axis, and the second holding surface has a curved cross-sectional shape when viewed in the axial direction of the rotation axis that is concave toward the side opposite the object to be measured in the held state.
In addition, in the above-mentioned conductor deterioration detection device, the inspection base is formed concavely toward the downward direction in the up-down direction perpendicular to the axial direction, and when viewed from the axial direction of the rotation axis, has a guide portion that guides the object to be measured held by the holding mechanism toward a target contact position, and the target contact position is a contact position corresponding to the first contact point of the contact surface with which the outer peripheral surface of the object to be measured contacts, the outer peripheral surface being arranged so that the central axis of the object to be measured is perpendicular to the central axis of the excitation coil and the central axis of the detection coil in the held state.

The conductor deterioration detection device according to the present invention has the advantage of being able to suppress misalignment in the width direction due to differences in the outer diameter of the wire held by the holding mechanism, thereby suppressing a decrease in detection accuracy.

FIG. 1 is a perspective view showing a state in which an electric wire is attached to a conductor deterioration detection device according to an embodiment. FIG. 2 is a block diagram showing a functional configuration of a conductor deterioration detection device according to an embodiment. FIG. 3 is a perspective view showing a schematic configuration of a conductor deterioration detection device according to an embodiment. FIG. 4 is a partial cross-sectional view of a main part of a conductor deterioration detection device according to an embodiment. FIG. 5 is a partial cross-sectional view showing a state in which a large-diameter electric wire is attached to a conductor deterioration detection device according to an embodiment. FIG. 6 is a partial cross-sectional view showing a state in which a medium-diameter electric wire is attached to a conductor deterioration detection device according to an embodiment. FIG. 7 is a partial cross-sectional view showing a state in which a small diameter electric wire is attached to a conductor deterioration detection device according to an embodiment. FIG. 8 is a schematic diagram showing the positional relationship between the rotation axis of the first arm portion in the conductor deterioration detection device and the central axes of the electric wires having different outer diameters, as viewed from the axial direction of the rotation axis. FIG. 9 is a schematic diagram for explaining the curved shape of the second holding surface in the conductor deterioration detection device. FIG. 10(A) is a table showing the relationship between the widthwise deviation of a wire and the output value of a conductor deterioration detection device, and FIG. 10(B) is a graph showing the relationship between the widthwise deviation of a wire and the attenuation rate of the output value of a conductor deterioration detection device. 11A and 11B are schematic diagrams showing a schematic configuration of a conductor deterioration detection device according to a modified example of the embodiment. 12A and 12B are schematic diagrams showing a schematic configuration of a conductor deterioration detection device according to a modified example of the embodiment. 13A and 13B are schematic diagrams showing a schematic configuration of a conductor deterioration detection device according to a modified example of the embodiment.

Below, an embodiment of a conductor deterioration detection device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. Furthermore, the components in the following embodiment include those that a person skilled in the art would easily imagine, or those that are substantially the same. Furthermore, the components in the following embodiment can be omitted, replaced, or modified in various ways without departing from the gist of the invention.

[Embodiment]
FIG. 1 is a perspective view showing an electric wire mounting state of the conductor deterioration detection device according to the present embodiment. FIG. 2 is a block diagram showing the functional configuration of the conductor deterioration detection device. FIG. 3 is a perspective view showing a schematic configuration of the conductor deterioration detection device. FIG. 4 is a partial cross-sectional view of a main part of the conductor deterioration detection device. FIG. 5 is a partial cross-sectional view showing a large diameter electric wire mounting state of the conductor deterioration detection device. FIG. 6 is a partial cross-sectional view showing a medium diameter electric wire mounting state of the conductor deterioration detection device. FIG. 7 is a partial cross-sectional view showing a small diameter electric wire mounting state of the conductor deterioration detection device. FIG. 8 is a schematic view showing the positional relationship between the rotation axis of the first arm part in the conductor deterioration detection device and each central axis of the electric wires having different outer diameters, as viewed from the axial direction of the rotation axis. FIG. 9 is a schematic view for explaining the curved shape of the second holding surface in the conductor deterioration detection device. FIG. 10(A) is a table showing the relationship between the width direction deviation of the electric wire and the output value of the conductor deterioration detection device, and FIG. 10(B) is a graph showing the relationship between the width direction deviation of the electric wire and the attenuation rate of the output value of the conductor deterioration detection device. 5 to 9 and 11(A) to 13(B), the detection coil 11 housed in the housing 4 is omitted.

Here, the X direction in Figures 1 to 9 (including Figures 11(A) to 13(B)) is the width direction of the conductor deterioration detection device in this embodiment. The Y direction is the depth direction of the conductor deterioration detection device in this embodiment, and is a direction perpendicular to the width direction. The Z direction is the up-down direction of the conductor deterioration detection device in this embodiment, and is a direction perpendicular to the width direction and the depth direction. Note that the Z direction is described as, for example, the vertical direction of the conductor deterioration detection device in this embodiment, and the Z1 direction of the Z direction is the vertical upper side, and the Z2 direction is the vertical lower side.

The conductor deterioration detection device 1 according to this embodiment is an inspection device that detects deterioration of the conductor W1 of the electric wire W to be measured by using the so-called eddy current testing (ECT). The electric wire W includes a conductor W1 and an insulating coating W2 that covers the conductor W1. The conductor W1 is a core wire formed by bundling or twisting a plurality of conductive metal wires. The insulating coating W2 is made of an insulating resin material, and covers and insulates the outer peripheral surface (outer surface) of the conductor W1. The electric wire W is formed so that the cross-sectional shape in the direction perpendicular to the extension direction of the electric wire W is approximately circular, and the conductor W1 and the insulating coating W2 extend linearly with approximately the same diameter along the extension direction of the electric wire W. The conductor deterioration detection device 1 generates an eddy current in the conductor W1 of the electric wire W by using a magnetic field (magnetic flux) generated by the excitation coil 10, and detects deterioration of the conductor W1 by detecting a magnetic field (magnetic flux) generated in the conductor W1 by the detection coil 11.

The deterioration of the conductor W1 inspected by the conductor deterioration detection device 1 is corrosion of the conductor W1, which occurs due to, for example, aging. In the following description, the electric wire W inspected by the conductor deterioration detection device 1 is described as, for example, an overhead power distribution line suspended in the air via a utility pole or the like, but is not limited to this. In addition, the electric wire W inspected by the conductor deterioration detection device 1 is the inspection target electric wire Ws that is the inspection target among multiple types of electric wires W with different outer diameters. In this embodiment, for example, the outer diameter φD1 of the large diameter electric wire Ws1 with the largest outer diameter among the inspection target electric wires Ws is described as φ21, the outer diameter φD3 of the small diameter electric wire Ws3 with the smallest outer diameter is described as φ9, and the outer diameter φD2 of the medium diameter electric wire Ws2 between the large diameter electric wire Ws1 and the small diameter electric wire Ws3 is described as φ15, but is not limited to these. As shown in FIG. 2, the conductor deterioration detection device 1 includes a detection unit 2 and a power supply unit 3.

The detection unit 2 is a part that detects deterioration of the conductor W1 in the electric wire Ws to be inspected. The detection unit 2 is electrically connected to the power supply unit 3 and is driven by receiving power from the power supply unit 3. The detection unit 2 includes a housing 4, an excitation coil 10, and a detection coil 11.

The housing 4 is a box-shaped member in which the excitation coil 10 and detection coil 11 are provided. The housing 4 is made of a non-magnetic material having insulating properties. The housing 4 is formed in a substantially rectangular box shape with the extension direction of the electric wire Ws to be inspected being the long side direction. The housing 4 has an inspection base 5, a holding mechanism 6, and a housing main body 7. The housing main body 7 is formed to be hollow inside, and the excitation coil 10 and detection coil 11 are housed inside. When the electric wire Ws to be inspected is in the air, the housing 4 is positioned vertically above the inspection base 5 in a holding state in which the electric wire Ws to be inspected is held by the holding mechanism 6, as shown in FIG. 1.

The excitation coil 10 and the detection coil 11 are formed by concentrically winding a conductive metal wire (e.g., copper wire) multiple times, and are formed into a ring shape. The excitation coil 10 and the detection coil 11 have the same shape. As shown in FIG. 2, the excitation coil 10 and the detection coil 11 are arranged so that they overlap each other when viewed from the axial direction of the central axis 10a of the excitation coil 10 or the central axis 11a of the detection coil 11, and are held side by side in the extension direction. The excitation coil 10 and the detection coil 11 are electrically connected to the power supply unit 3. The excitation coil 10 generates a magnetic field (magnetic flux) when an alternating current is applied from the power supply unit 3, and the generated magnetic field causes an induced current to flow in the conductor W1 due to a magnetic flux change of the magnetic field corresponding to the eddy current. The detection coil 11 causes an induced current to flow due to a magnetic flux change of the magnetic field corresponding to the eddy current generated in the conductor W1. The induced current generated in the detection coil 11 flows toward the power supply unit 3.

The power supply unit 3 applies an alternating current to the excitation coil 10 and outputs a detection signal based on the induced current flowing through the detection coil 11. The power supply unit 3 has a power supply circuit 12, an oscillator circuit 13, an amplifier circuit 14, and a noise filter 15. The power supply unit 3 is electrically connected to a signal analysis device 16.

The power supply circuit 12 is electrically connected to an external AC power supply (not shown) and the oscillator circuit 13, and for example, supplies power to the oscillator circuit 13. The oscillator circuit 13 is electrically connected to the amplifier circuit 14, and for example, in response to power supply from the power supply circuit 12, outputs an AC current to the excitation coil 10 via the amplifier circuit 14 to excite it and generate a magnetic field. The amplifier circuit 14 is electrically connected to the excitation coil 10, and for example, amplifies the AC current output from the oscillator circuit 13. The noise filter 15 is electrically connected to the detection coil 11 and removes noise components from the detection signal based on the induced current generated in the detection coil 11. The signal analysis device 16 is, for example, a spectrum analyzer, an oscilloscope, etc., and displays the waveform of the detection signal output from the detection coil 11 through the noise filter 15. The operator can determine whether the conductor W1 in the inspection target electric wire Ws has deteriorated based on the signal waveform displayed or output by the signal analysis device 16.

The inspection base 5 is a part of the housing 4 and is the part that comes into contact with the electric wire Ws to be inspected. The inspection base 5 is provided on the vertically lower side of the housing 4. The inspection base 5 has a contact surface 21, a guide portion 22, a rotation shaft 23, and a grip portion 24.

The contact surface 21 is formed facing vertically downward and is a portion that comes into contact with the test target electric wire Ws at the first contact point G when the test target electric wire Ws is held by the holding mechanism 6. The first contact point G is a contact point where the outer circumferential surface of the test target electric wire Ws comes into contact with the contact surface 21 when the test target electric wire Ws is held by the holding mechanism 6. As shown in FIG. 4, the first contact point G is preferably located on an imaginary line P when the central axis 11a of the detection coil 11 and the central axis Os of the test target electric wire Ws are arranged so as to be perpendicular to each other when the test target electric wire Ws is held by the holding mechanism 6.

The guide portion 22 is formed concavely downward in the up-down direction, and is a portion that guides the test target electric wire Ws held by the holding mechanism 6 toward the target contact position when viewed from the axial direction of the rotating shaft 23. Here, the target contact position is a contact position corresponding to the first contact point G of the contact surface 21 where the outer circumferential surface of the test target electric wire Ws, which is arranged so that the central axis Os of the test target electric wire Ws is perpendicular to the central axis 10a of the exciting coil 10 and the central axis 11a of the detecting coil 11, comes into contact in the above-mentioned holding state. Specifically, the cross-sectional shape of the guide portion 22 when viewed from the axial direction of the rotating shaft 23 is U-shaped, and opens diagonally downward. The guide portion 22 has a bearing through hole 22a formed parallel to the contact surface 21 and penetrating in the depth direction.

The pivot shaft 23 fits into the bearing through hole 22a (Fig. 4) of the guide portion 22, which protrudes vertically downward from the inspection base 5, and supports the holding mechanism 6 so that it can rotate freely. The axial direction of the pivot shaft 23 is parallel to the depth direction of the conductor deterioration detection device 1.

The gripping portion 24 is connected to the lower end of the guide portion 22 in the vertical direction and is formed by extending downward in the vertical direction. The gripping portion 24 is a portion that is temporarily gripped by an operator with his/her fingers when the operator attaches the conductor deterioration detection device 1 to an overhead power distribution line. As shown in FIG. 1 and FIG. 3, the gripping portion 24 has a through hole 24a through which a rubber rope 50 is inserted. One end of the rope 50 is attached to the second arm portion 31 of the holding mechanism 6. When the operator grips the other end of the rope 50 and pulls it downward in the vertical direction, the second arm portion 31 rotates from the release position to the holding position around the pivot shaft 23. The holding position is the position of the second arm portion 31 in the holding state in which the inspection target electric wire Ws is held by the holding mechanism 6. The release position is the position of the second arm portion 31 where the inspection target electric wire Ws is released from the holding state. The rope 50 is covered by a protective member 51 in the area where it comes into contact with the gripping portion 24 and the through hole 24a.

As shown in Figs. 5 to 7, the holding mechanism 6 is provided on the inspection base 5 side, and holds the inspection target electric wire Ws between the inspection base 5 and the holding mechanism 6 when the inspection target electric wire Ws is in contact with the inspection base 5. The holding mechanism 6 has a first arm portion 30 and a second arm portion 31.

The first arm portion 30 is formed to be rotatable around the pivot shaft 23, and is a portion that contacts the outer peripheral surface of the test target electric wire Ws at the second contact H and the third contact I when the test target electric wire Ws is held by the holding mechanism 6. The pivot shaft 23 is, for example, made of an insulating resin material and is configured by a hinge pin that is a long and thin rod-shaped member. In other words, the holding mechanism 6 includes a portion that supports the first arm portion 30 rotatably by the hinge pin. When viewed from the axial direction (Y direction) of the pivot shaft 23, the first arm portion 30 is formed in an L-shape or a V-shape, and one end is connected to the second arm portion 31. When viewed from the axial direction of the pivot shaft 23, the first arm portion 30 and the second arm portion 31 are formed in an approximately S-shape.

The first arm portion 30 has a first holding surface 32 and a second holding surface 33 that is provided farther from the rotation shaft 23 than the first holding surface 32 when viewed in the axial direction of the rotation shaft 23. When the first arm portion 30 is in a holding state in which the electric wire Ws to be inspected is held by the holding mechanism 6, the outer peripheral surface of the electric wire Ws to be inspected comes into contact with the first holding surface 32, and the outer peripheral surface comes into contact with the second holding surface 33. Therefore, when the electric wire Ws to be inspected is held by the holding mechanism 6, the contact point where the outer peripheral surface of the electric wire Ws to be inspected comes into contact with the first holding surface 32 is the second contact point H. On the other hand, when the electric wire Ws to be inspected is held by the holding mechanism 6, the contact point where the outer peripheral surface of the electric wire Ws to be inspected comes into contact with the second holding surface 33 is the third contact point I.

The first holding surface 32 has a linear cross-sectional shape when viewed from the axial direction of the pivot shaft 23. On the other hand, the second holding surface 33 has a curved cross-sectional shape when viewed from the axial direction of the pivot shaft 23, which is concave on the side opposite to the side of the electric wire Ws to be inspected when the electric wire Ws to be inspected is held by the holding mechanism 6.

9, the second holding surface 33 is formed so as to circumscribe an imaginary circle V of, for example, φ45.07 when viewed from the axial direction of the rotation shaft 23. In order to hold the test subject electric wires Ws having different outer diameters with the first arm portion 30 having a fixed shape so as to contact them at the target contact position on the contact surface 21, for example, from a geometrical standpoint, it is necessary to make one or two sides of the movable side have an arc shape.

In this embodiment, one side is flat and the other side is curved, so that the central axis Os of the test target electric wire Ws does not deviate from the virtual line P, and the test target electric wire Ws is in contact with the target contact position on the contact surface 21 of the inspection base 5 in the state in which the test target electric wire Ws is held by the holding mechanism 6. The size of the virtual circle U varies depending on the outer diameter of the test target electric wire, the position of the rotation axis 23, the angle and shape of the first holding surface 32 or the second holding surface 33, etc., but the circle circumscribing each of the test target electric wires Ws with outer diameters φ21, φ15, and φ9 is a virtual circle V with a diameter of φ45.07 (FIG. 9). The second contact H is located on the rotation axis 23 side of the virtual line P passing through the first contact G and the central axis Os of the test target electric wire Ws when viewed from the axial direction of the rotation axis 23 in the state in which the test target electric wire Ws is held by the holding mechanism 6. The third contact I has a corresponding contact position located on the opposite side of the rotation shaft 23 across the imaginary line P when viewed from the axial direction of the rotation shaft 23 in a state in which the electric wire Ws to be inspected is held by the holding mechanism 6. As shown in Figures 5 to 7, regardless of the difference in outer diameter, the electric wire Ws to be inspected is held from three directions by the inspection base 5 and the holding mechanism 6 at three points, the first contact G, the second contact H, and the third contact I, in a state in which the electric wire Ws to be inspected is held by the holding mechanism 6.

The second arm portion 31 is a portion that rotates the first arm portion 30 in the rotation direction of the rotation shaft 23 by an external force. The second arm portion 31 is formed to be rotatable around the rotation shaft 23, like the first arm portion 30, and rotates between the holding position and the open position described above. As shown in Figs. 1 and 3, the second arm portion 31 is formed to extend along the direction away from the rotation shaft 23, and an operator can grasp the end portion in the direction away to rotate the second arm portion 31. The holding mechanism 6 has a coil spring 35 that biases the first arm portion 30 and the second arm portion 31 to rotate around the rotation shaft from the open position toward the holding position. The coil spring 35 is a metal torsion coil spring, and a hinge pin is arranged inside. One end of the coil spring 35 is engaged with the inspection base 5 side, and the other end is engaged with the second arm portion 31 side.

In the conductor deterioration detection device 1 of this embodiment, as shown in Fig. 5, the distance T1 in the vertical direction perpendicular to the axial direction between the contact surface 21 on the inspection base 5 and the rotation axis 23 is shorter than the distance T2 in the vertical direction between the contact surface 21 of the inspection base 5 and the central axis Os1 of the large diameter electric wire Ws1 when the large diameter electric wire Ws1 is held by the holding mechanism 6. When the distance T1 is set shorter than the distance T2 (T1 < T2), as shown in Fig. 8, the virtual line P is approximately tangent to the virtual circle U whose radius is the line connecting the rotation axis 23 and the central axis Os1 of the large diameter electric wire Ws1, and the central axes Os1, Os2, and Os3 are approximately overlapping with the virtual circle U, so that the widthwise deviation of the holding position of each inspection target electric wire Ws as viewed from the axial direction of the rotation axis 23 can be minimized. For example, in the state where the large diameter electric wire Ws1 is held, the distance between the imaginary lines Q and P that pass through the rotation axis 23 and are perpendicular to the contact surface 21 is defined as L1 (FIG. 5). In the state where the medium diameter electric wire Ws2 is held, the distance between the imaginary lines Q and P is defined as L2 (FIG. 6). In the state where the small diameter electric wire Ws3 is held, the distance between the imaginary lines Q and P is defined as L3 (FIG. 7). When the distance L1 is taken as the reference, in the above configuration, when T1<T2, L2≒L1 and L3≒L1.

Next, an example of an inspection method using the conductor deterioration detection device 1 will be described. As described above, the conductor deterioration detection device 1 biases the coil spring 35 in a direction that opens the holding mechanism 6, that is, in a direction from the holding position to the open position around the pivot shaft 23.

First, with the holding mechanism 6 open, the worker hooks the detection unit 2 of the conductor deterioration detection device 1 onto the electric wire Ws to be inspected. When hooking the detection unit 2 onto the electric wire Ws to be inspected, the worker, for example, climbs a utility pole and while holding the gripping unit 24, inserts the electric wire Ws to be inspected toward the inspection base 5 through the opening of the guide unit 22. Also, when the worker works on the ground without climbing a utility pole, for example, while holding a rod-shaped member one end of which is connected to the gripping unit 24, inserts the electric wire Ws to be inspected toward the inspection base 5 through the opening of the guide unit 22.

Next, the worker pulls the rope 50 vertically downward to move the second arm 31 connected to one end of the rope 50 and close the holding mechanism 6. This causes the holding mechanism 6 to rotate from the open position to the holding position around the pivot 23. At this time, the worker may pull the rope 50 directly with his or her fingers, or may connect a weight to the other end of the rope 50 and use the load of the weight to pull the rope 50 vertically downward.

Then, the worker performs a predetermined operation to start the power supply unit 3 to supply electricity to the detection unit 2, and performs conductor deterioration detection for the electric wire Ws to be inspected. At this time, the worker continues to pull the rope 50 vertically downward so as to maintain the holding mechanism 6 in the holding position. Then, the worker measures the presence or absence of conductor deterioration of the electric wire Ws to be inspected while observing the signal waveform displayed on the signal analysis device 16.

Next, after the measurement is completed, the worker releases the rope 50 that was being pulled vertically downward to open the holding mechanism 6. This causes the holding mechanism 6 to rotate from the holding position to the open position around the pivot shaft 23 and enter the open state. Next, while keeping the detection unit 2 hooked on the electric wire Ws to be inspected and the holding mechanism 6 open, the worker moves the conductor deterioration detection device 1 by pulling the rope 50 in either direction of the extension of the electric wire Ws to be inspected. After moving the conductor deterioration detection device 1, the worker performs the measurement using the above procedure.

When the operator finishes the measurement, he or she removes the detection unit 2 from the electric wire Ws to be inspected with the holding mechanism 6 open. When removing the detection unit 2 from the electric wire Ws to be inspected, the operator, for example, climbs a utility pole and while holding the gripping unit 24, takes the electric wire Ws to be inspected from the inspection base 5 side to the outside through the opening of the guide unit 22. Also, when the operator works on the ground without climbing a utility pole, for example, he or she holds a rod-shaped member one end of which is connected to the gripping unit 24 and takes the electric wire Ws to be inspected to the outside through the opening of the guide unit 22.

Figure 10 (A) is a table showing an example of the change in the output value (detection value) [mV] and attenuation rate [%] of the conductor deterioration detection device with respect to the shift [mm] in the width direction of the inspection target electric wire Ws. Figure 10 (B) is a graph showing an example of the relationship between the shift in the width direction of the inspection target electric wire Ws and the attenuation rate. In Figure 10 (A), the reference position is when the shift in the width direction of the inspection target electric wire Ws is 0 [mm], the output value at that time is 12.6 [mV], and when the output value at 2.5 [mm] is 10.5 [mV], the attenuation rate is (12.6-10.5)/12.6 ≒ 0.16 (16.7 [%]). As shown in Figure 10 (B), the attenuation rate increases at a constant rate when the inspection target electric wire Ws is shifted in the width direction from the reference position, but the rate of increase decreases when the shift amount exceeds 5 [mm]. In this way, by suppressing the positional shift in the width direction when the test target electric wire Ws is held in the conductor deterioration detection device 1, it is possible to prevent a decrease in the detection value and suppress a decrease in the detection accuracy of the conductor deterioration detection device 1.

In the conductor deterioration detection device 1 of this embodiment, for example, when the widthwise deviation from the position of the large diameter electric wire Ws1 completely held by the holding mechanism 6 is 0 [mm], the widthwise deviation when the medium diameter electric wire Ws2 is held is 0.19 [mm], and the widthwise deviation when the small diameter electric wire Ws3 is held is 0.03 [mm]. As a result, the attenuation rate of both the medium diameter electric wire Ws2 and the small diameter electric wire Ws3 is 1.3% or less. As a result, when electric wires W with different outer diameters are inspected, the conductor deterioration detection device 1 can suppress the decrease in the detection accuracy of the presence or absence of deterioration of the conductor W1 by suppressing the widthwise deviation of the electric wire W held by the holding mechanism 6 and reducing the decrease in the detection value.

As described above, in the conductor deterioration detection device 1 of this embodiment, the holding mechanism 6 brings the test target electric wire Ws into contact with the test base 5, and the first arm portion 30 contacts the outer circumferential surface of the test target electric wire Ws in the held state at the second contact point H and the third contact point I. This makes it possible for the holding mechanism 6 to hold the test target electric wire Ws at three points, and the test target electric wire Ws can be stably held.

When viewed from the axial direction of the pivot shaft 23, the contact position of the first arm portion 30 corresponding to the second contact H is located on the pivot shaft 23 side of the imaginary line P, and the contact position corresponding to the third contact I is located on the opposite side of the pivot shaft 23 across the imaginary line P. This prevents the second contact H and the third contact I from being offset relative to the first contact G, making it possible to support the electric wire Ws to be inspected from three different directions, and to stably hold the electric wire Ws to be inspected.

The distance T1 in the vertical direction perpendicular to the axial direction between the contact surface 21 on the inspection base 5 and the pivot shaft 23 is shorter than the distance T2 in the vertical direction between the contact surface 21 of the inspection base 5 and the central axis Os1 of the large diameter electric wire Ws1 when the large diameter electric wire Ws1 is held by the holding mechanism 6. In the above configuration, for example, if the distance T1A is set longer than the distance T2, as shown in FIG. 8, the virtual line P intersects without touching the virtual circle UA whose radius is the line connecting the virtual pivot shaft 23A and the central axis Os1 of the large diameter electric wire Ws1, and the central axes Os2 and Os3 are not in a position overlapping with the virtual circle UA, so that the holding position of the large diameter electric wire Ws1 as viewed from the axial direction of the pivot shaft 23 and the holding positions of the medium diameter electric wire Ws2 and the small diameter electric wire Ws3 are misaligned in the width direction. For example, if the widthwise deviation from the position of the large diameter electric wire Ws1 completely held by the holding mechanism 6 is 0 [mm], the widthwise deviation when the medium diameter electric wire Ws2 is held is 2.53 [mm], and the widthwise deviation when the small diameter electric wire Ws3 is held is 4.76 [mm].

On the other hand, when distance T1 is set shorter than distance T2, imaginary line P is approximately tangent to imaginary circle U whose radius is the line connecting rotation shaft 23 and central axis Os1 of large diameter electric wire Ws1, and central axes Os1, Os2, and Os3 are approximately overlapping with imaginary circle U, so that it is possible to minimize the widthwise shift of the holding position of each inspection target electric wire Ws as viewed from the axial direction of rotation shaft 23. In this way, with the above configuration, it is possible to suppress the widthwise shift caused by the difference in outer diameter of the inspection target electric wire Ws held by holding mechanism 6, and suppress the deterioration of detection accuracy.

In addition, in the conductor deterioration detection device 1 in this embodiment, the first arm portion 30 has a linear cross-sectional shape as viewed from the rotation axis direction of the first holding surface 32 having the second contact H, and a curved cross-sectional shape as viewed from the rotation axis direction of the second holding surface 33 having the third contact I. If the cross-sectional shapes as viewed from the rotation axis direction of the first and second holding surfaces 32, 33 are both linear, the inspection target electric wire Ws will be shifted in the width direction due to the difference in the outer diameter of the inspection target electric wire Ws held by the first arm portion 30, whose shape is fixed, from a geometrical perspective. On the other hand, by making the cross-sectional shape as viewed from the rotation direction of the second holding surface 33 curved, it is possible to absorb the widthwise shift of the inspection target electric wire Ws relative to the reference position when holding the inspection target electric wires Ws with different outer diameters. The angle formed between the first holding surface 32 and the second holding surface 33 is preferably 90° when the second holding surface 33 is a flat surface.

In addition, in the conductor deterioration detection device 1 of this embodiment, the guide portion 22 on the inspection base 5 guides the inspection target electric wire Ws inserted inside the concave portion toward the contact surface 21, making it possible to smoothly make contact between the inspection target electric wire Ws and the inspection base 5.

In addition, when the conductor deterioration detection device 1 in this embodiment performs an inspection on the inspection target electric wire Ws in the air, the housing 4 is positioned vertically above the inspection base 5. This causes the second arm portion 31 to face downward, making it possible for an operator working from below in the vertical direction to easily operate the second arm portion 31 directly or indirectly.

In the above embodiment, the rope 50 is simply inserted through the through hole 24a of the gripping portion 24, but the present invention is not limited to this. Figures 11(A), 11(B), 12(A), 12(B), 13(A), and 13(B) are schematic diagrams showing the general configuration of a conductor deterioration detection device according to a modified embodiment. Note that the coil spring 35 is omitted in Figures 12(A) and 12(B). The coil spring 35 shown in Figures 11(A) to 12(B) is biased in a direction to open the holding mechanism 6, that is, in a direction from the holding position to the open position around the pivot shaft 23. The coil spring 35 shown in Figures 13(A) and 13(B) is biased in a direction to close the holding mechanism 6, that is, in a direction from the open position to the holding position around the pivot shaft 23.

As shown in Figs. 11(A) to 12(B), the conductor deterioration detection device 1A according to the modified embodiment is provided with a lock cam 52 that rotates around a pivot 52a relative to the gripping portion 24. The pivot 52a is arranged with its axial direction parallel to the axial direction of the pivot 23. As the holding mechanism 6 rotates counterclockwise around the pivot 23 due to the biasing force of the coil spring 35, the rope 50 is pulled vertically upward, and the lock cam 52 rotates clockwise around the pivot 52a due to the frictional force of the contact surface between the lock cam 52 and the rope 50 (Fig. 11(A)). As a result, the lock cam 52 clamps the rope 50 between itself and the inner wall of the through hole 24a, locking the rope 50 to the gripping portion 24.

When the rope 50 is pulled vertically downward (in the direction of the arrow in FIG. 11(B)) while the test target electric wire Ws is held by the holding mechanism 6, the holding mechanism 6 does not rotate and the rope 50, which is an elastic body, stretches vertically downward, but then recoils vertically upward due to its elasticity. As a result, the lock cam 52 clamps the rope 50 between itself and the inner wall of the through hole 24a, fixing the rope 50 to the gripping portion 24 (FIG. 12(A)). This eliminates the need for the operator to constantly pull the rope vertically downward during measurement, reducing the workload.

When releasing the electric wire Ws to be inspected from the holding mechanism 6, the worker needs to pull the rope 50. Then, while pulling the rope 50 vertically downward, the worker changes the pulling direction to a direction approximately perpendicular to the extension direction of the second arm portion 31, thereby unlocking the lock cam 52, freeing the rope 50, and releasing the electric wire Ws to be inspected from the holding mechanism 6 (FIG. 12 (B)).

As shown in Figs. 13(A) and 13(B), the conductor deterioration detection device 1B according to the modified embodiment has a roller 53 that rotates around a rotation axis 53a with respect to the gripping portion 24. The rotation axis 53a is arranged so that its axial direction is parallel to the axial direction of the rotation axis 23. The roller 53 is arranged vertically below the inner wall of the through hole 24a, and reduces sliding between the rope 50 and the inner wall of the through hole 24a. The roller 53 rotates in response to movement of the rope 50 in the extension direction.

The worker opens the holding mechanism 6 by pushing the second arm portion 31 vertically upward, and inserts the electric wire Ws to be inspected through the opening of the guide portion 22 toward the inspection base 5. At this time, the rollers 53 allow the rope 50 to move smoothly without sliding against the inner wall of the through hole 24a. Next, when the worker releases the second arm portion 31, the force of the coil spring 35 closes the holding mechanism 6. The worker then pulls the rope 50 vertically downward to completely close the holding mechanism 6. At this time, if a weight is connected to the other end of the rope 50 as described above, the worker does not need to constantly pull the rope 50, and the workload can be reduced.

After completing the measurement, the operator releases the rope 50 that was being pulled vertically downward, and pushes the second arm portion 31 vertically upward to open the holding mechanism 6. In this way, the roller 53 rotates, allowing the rope 50 to move smoothly without sliding against the inner wall of the through hole 24a.

In the above embodiment, the housing 4 houses the excitation coil 10 and the detection coil 11 as the detection unit 2, but this is not limited to this. For example, the housing 4 may house the power supply unit 3 in addition to the detection unit 2.

REFERENCE SIGNS LIST 1 Conductor deterioration detection device 4 Housing 5 Inspection base 6 Holding mechanism 10 Excitation coil 11 Detection coil 21 Contact surface 22 Guide portion 23 Rotation shaft 30 First arm portion 31 Second arm portion 32 First holding surface 33 Second holding surface G First contact H Second contact I Third contact

Claims (4)

An excitation coil that generates an eddy current in an object to be measured having a circular cross-sectional shape ;
a detection coil for detecting a magnetic flux due to an eddy current generated in the object to be measured;
a housing that houses the excitation coil and the detection coil,
The housing includes:
an inspection base formed of a non-magnetic material and having a contact surface that comes into contact at a first contact point with a plurality of types of objects to be measured having different outer diameters;
a holding mechanism for holding the object to be measured between the object to be measured and the inspection base in a contact state in which the object to be measured is in contact with the inspection base,
The holding mechanism includes:
a first arm portion that is formed to be rotatable about a rotation axis and that comes into contact with an outer circumferential surface of the object to be measured at a second contact point and a third contact point when the object to be measured is in a held state in which the object to be measured is held by the holding mechanism;
a second arm portion that rotates the first arm portion in a rotation direction of the rotation shaft by an external force between a holding position in the holding state and a release position at which the object to be measured is released from the holding state,
In the held state, the object is held so that an outer peripheral surface of the object to be measured, which is disposed so that a central axis of the object to be measured and a central axis of the detection coil are perpendicular to each other, and the outer peripheral surface of the object to be measured is held so that the outer peripheral surface of the object to be measured and the contact surface of the inspection base are in contact with each other at the first contact point;
The first contact is
In the held state, when viewed from the axial direction of the rotation shaft, the detection coil is disposed on a virtual line that passes through a central axis of the detection coil, is perpendicular to the contact surface of the inspection base, and passes through a central axis of the object to be measured,
The second contact is
In the held state, when viewed from the axial direction of the rotation shaft, the first contact point is disposed on the rotation shaft side of the imaginary line passing through the first contact point and a central axis of the object to be measured,
The third contact is
In the held state, when viewed from the axial direction of the rotation shaft, the holding member is disposed on the opposite side to the rotation shaft across the virtual line.
A conductor deterioration detection device comprising: An excitation coil that generates an eddy current in an object to be measured having a circular cross-sectional shape ;
a detection coil for detecting a magnetic flux due to an eddy current generated in the object to be measured;
a housing that houses the excitation coil and the detection coil,
The housing includes:
an inspection base formed of a non-magnetic material and having a contact surface that comes into contact at a first contact point with a plurality of types of objects to be measured having different outer diameters;
a holding mechanism for holding the object to be measured between the object to be measured and the inspection base in a contact state in which the object to be measured is in contact with the inspection base,
The holding mechanism includes:
a first arm portion that is formed to be rotatable about a rotation axis and that comes into contact with an outer circumferential surface of the object to be measured at a second contact point and a third contact point when the object to be measured is in a held state in which the object to be measured is held by the holding mechanism;
a second arm portion that rotates the first arm portion in a rotation direction of the rotation shaft by an external force between a holding position in the holding state and a release position at which the object to be measured is released from the holding state,
In the held state, the object is held so that an outer peripheral surface of the object to be measured, which is disposed so that a central axis of the object to be measured and a central axis of the detection coil are perpendicular to each other, and the outer peripheral surface of the object to be measured is held so that the outer peripheral surface of the object to be measured and the contact surface of the inspection base are in contact with each other at the first contact point;
The first contact is
In the held state, when viewed from the axial direction of the rotation shaft, the detection coil is disposed on a virtual line that passes through a central axis of the detection coil, is perpendicular to the contact surface of the inspection base, and passes through a central axis of the object to be measured,
The second contact is
In the held state, when viewed from the axial direction of the rotation shaft, the first contact point is disposed on the rotation shaft side of the imaginary line passing through the first contact point and a central axis of the object to be measured,
The third contact is
In the held state, when viewed from an axial direction of the rotation shaft, the holding member is disposed on an opposite side to the rotation shaft across the virtual line,
The distance between the contact surface on the inspection base and the rotation axis in a vertical direction perpendicular to the axial direction is
when the large-diameter electric wire having the largest outer diameter among the objects to be measured is held by the holding mechanism, the distance is shorter than the distance in the up-down direction between the contact surface of the inspection base and the central axis of the large-diameter electric wire,
A conductor deterioration detection device comprising: The first arm portion is
a first support surface having a contact location corresponding to the second contact;
a second holding surface that is provided farther from the rotation shaft than the first holding surface when viewed from the axial direction of the rotation shaft and has a position corresponding to the third contact point;
The first holding surface is
The cross-sectional shape as viewed from the axial direction of the rotation shaft is linear,
The second holding surface is
a cross-sectional shape of the rotating shaft as viewed from an axial direction thereof is curved so as to be recessed toward a side opposite to the object to be measured in the held state;
The conductor deterioration detection device according to claim 1 or 2. The inspection base includes:
a guide portion that is formed in a concave shape toward a downward direction in a vertical direction perpendicular to the axial direction and that guides each of the objects to be measured held by the holding mechanism toward a target contact position when viewed from the axial direction of the rotation shaft,
The target contact position is
a contact position corresponding to the first contact point of the contact surface with which an outer circumferential surface of the object to be measured contacts, the outer circumferential surface of the object to be measured being arranged so that a central axis of the object to be measured is perpendicular to a central axis of the excitation coil and a central axis of the detection coil in the held state.
The conductor deterioration detection device according to claim 1 or 2.

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