JP2020003288A - Degradation detection method and degradation detection device - Google Patents

Abstract

To provide a degradation detection method and a degradation detection device designed to improve the accuracy of detecting degradation.SOLUTION: A control unit 17 sends an excitation signal to an excitation coil 11 causing an eddy current to be generated on an electric wire 2, and causes a detection signal corresponding to the eddy current to be outputted by a detection coil 12. The control unit 17 controls a motor 151 causing the excitation coil 11 and the detection coil 12 to be moved along a longitudinal direction D1, and obtains the output value of the detection signal for each movement and a phase difference between the excitation signal and the detection signal. The control unit 17 displays on a display unit 16 a graph in which a relationship between the output value of the obtained detection signal and the phase difference is mapped. An operator detects the corrosion state of the electric wire 2 on the basis of the graph displayed on the display unit 16.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a deterioration detection method and a deterioration detection device.

  As a conventional deterioration detection method, for example, an abnormality detection device described in Patent Document 1 has been proposed. The abnormality detection device of Patent Document 1 is intended to diagnose rust (hereinafter, corrosion) of an electric wire connected to a bushing of a transformer. An electric wire is sandwiched between clamp heads with built-in excitation coil and detection coil, and an excitation current is applied to the excitation coil to generate an eddy current in the electric wire. are doing.

  However, the conventional abnormality detection device has a problem that the accuracy is only high enough to detect the presence or absence of corrosion, and it is not possible to detect how much corrosion (deterioration) occurs.

JP 2007-271607 A

  The present invention has been made in view of the above background, and an object of the present invention is to provide a deterioration detection method and a deterioration detection device that improve detection accuracy of a deterioration state.

  A deterioration detection method according to an aspect of the present invention is a deterioration detection method for detecting a deterioration state of a conductor, in which an excitation signal is supplied to an excitation coil to generate an eddy current on the conductor, and a detection coil is used. An output step of outputting a detection signal corresponding to the eddy current, and a detection step of detecting a deterioration state of the conductor based on a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal. It is characterized by having.

  Further, the conductor is formed of a conductor of an electric wire, and in the output step, the excitation coil and the detection coil are moved along the longitudinal direction with respect to the conductor, and in the detection step, the excitation coil and the detection coil are moved. The deterioration state of the conductor may be detected based on the magnitude of the detection signal obtained each time the detection coil moves and the phase difference.

  In the detecting step, a graph is created by mapping a relationship between the magnitude of the detection signal obtained each time the excitation coil and the detection coil move, and the phase difference, and the conductor is formed based on the graph. May be detected.

  Further, a deterioration detection device according to an aspect of the present invention includes: an excitation coil for generating an eddy current in a conductor; and a detection coil for outputting a detection signal in accordance with the eddy current. The deterioration detection device for detecting a state further includes an output unit that outputs a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal.

  Further, a deterioration detection device according to an aspect of the present invention includes: an excitation coil for generating an eddy current in a conductor; and a detection coil for outputting a detection signal in accordance with the eddy current. The deterioration detection device for detecting a state further includes a detection unit that detects the conductor state based on a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal. .

  According to the above aspect, since the deterioration state of the conductor is detected based on both the magnitude of the detection signal and the phase difference between the excitation signal and the detection signal, the detection accuracy of the deterioration state can be improved. .

It is a block diagram showing one embodiment of a deterioration detection device which performed a deterioration detection method of the present invention. FIG. 2 is a front view showing an arrangement of electric wires, an excitation coil and a detection coil which constitute the deterioration detection device shown in FIG. 1. FIG. 2 is a side view showing an arrangement of electric wires, an excitation coil and a detection coil which constitute the deterioration detection device shown in FIG. 9 is a graph showing frequency characteristics of output values of detection signals for a reference sample and samples A to G. 7 is a graph showing frequency characteristics of a phase difference between a detection signal and an excitation signal for a reference sample and samples A to G. 9 is a graph showing the relationship between the output of a detection signal for a reference sample and samples A to G, and the phase difference between the detection signal and the excitation signal. 3 is a flowchart illustrating a processing procedure of a control unit illustrated in FIG. 1.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. The deterioration detection device 1 shown in FIG. 1 is a device that detects a deterioration state (= corrosion state) of the conductor 22 of the electric wire 2. As shown in FIG. 2, the electric wire 2 includes a conductor 22 in which a plurality of strands 21 are twisted, and a covering portion 23 that covers the conductor 22.

  As illustrated in FIG. 1, the deterioration detection device 1 includes an excitation coil 11, a detection coil 12, an AC power supply 13, a detection unit 14, a coil moving unit 15, a display unit 16, and a control unit 17, Have.

  Each of the excitation coil 11 and the detection coil 12 is configured by winding a winding, for example, in a spiral shape. The excitation coil 11 is a coil for flowing an excitation signal (AC current) to induce an eddy current on the surface of the electric wire 2. The detection coil 12 is a coil through which an induced current flows due to a magnetic flux change due to an eddy current. The AC power supply 13 is a power supply that supplies an excitation signal to the excitation coil 11. The detection unit 14 detects an induced current flowing through the detection coil 12, and outputs the detection current as a detection signal. That is, the detection signal is a signal corresponding to the eddy current.

  The coil moving unit 15 moves the excitation coil 11 and the detection coil 12 along the longitudinal direction D1 of the electric wire 2. The coil moving unit 15 includes a main body (not shown) to which the excitation coil 11 and the detection coil 12 are attached and through which the electric wire 2 passes, and a motor shown in FIG. 1 for moving the main body along the longitudinal direction D1. 151.

  The main body (not shown) is provided with a rotating body such as a running roller inside the main body, and is movable along the longitudinal direction D1 with respect to the electric wire 2. As shown in FIG. 2, the excitation coil 11 and the detection coil 12 are attached to the main body so that the center axis A is along the radial direction D2 of the electric wire 2. Further, as shown in FIG. 3, the exciting coil 11 and the detecting coil 12 are arranged along the longitudinal direction D1, and are arranged so as to partially overlap each other.

  The display unit 16 as an output unit is for displaying a graph showing a relationship between an output value (magnitude of amplitude) of the detection signal and a phase difference between the detection signal and the excitation signal.

  The control unit 17 includes a microcomputer having a built-in CPU, ROM, RAM, and the like, and controls the entire deterioration detection device 1. The control unit 17 is connected to the AC power supply 13 and controls on / off of the AC power supply 13. The control unit 17 is connected to the motor 151, and drives the motor 151 to move the excitation coil 11 and the detection coil 12 along the longitudinal direction D1.

  The control unit 17 is connected to the detection unit 14, and receives the detection signal output from the detection unit 14. The control unit 17 obtains an output value and a phase difference of a detection signal detected each time the excitation coil 11 and the detection coil 12 move. In addition, the control unit 17 creates a graph (see FIG. 6) in which the obtained output value of the detection signal and the phase difference are plotted, and causes the display unit 16 to display the graph.

  Next, the principle of a deterioration detection method using the deterioration detection device 1 will be described with reference to FIGS. Results of measuring the output value and phase difference of the detection signal of the detection coil 12 by flowing an excitation signal of 1 kHz to 100 kHz to the excitation coil 11 with respect to the electric wires 2 of the samples A to C using the deterioration detection device 1 described above. Are shown in FIG. 4 and FIG. As the exciting coil 11 and the detecting coil 12, those having an inner diameter of 30 [mm] and a number of turns of 300 [T] were used.

  Note that Sample A is a sample that has not corroded. Sample B is a sample in which each element wire 21 is corroded except at the contact points, and medium-level corrosion has occurred. The sample C is a sample in which the wires 21 are uniformly corroded and a large level of corrosion has occurred.

  As shown in FIGS. 4 and 5, the output value of the detection signal of the corroded electric wire 2 is lower than that of the corroded electric wire 2, and the phase is delayed. The reason why the output value of the detection signal decreases is as follows. The corroded electric wire 2 has a larger resistance on the surface of the conductor 22 than the non-corroded electric wire 2, so that the eddy current generated on the surface of the conductor 22 is suppressed, and the output value decreases accordingly. The reason why the phase is delayed is as follows. When corrosion occurs on the surface of the wire 21, the corrosion between the wires 21 (electrodes) becomes an insulator, and each wire 21 becomes a pseudo capacitor. A phase delay occurs due to the capacitance component of the capacitor.

  As shown in FIG. 4, at about 10 kHz or less, the difference between the output values of the detection signals between the sample A where no corrosion has occurred and the sample B where the medium level corrosion has occurred is somewhat large. . However, the difference in the output value of the detection signal between the sample B in which the medium level corrosion has occurred and the sample C in which the large level corrosion has occurred is small. Above about 10 [kHz], on the contrary, the output value difference of the detection signal between the sample B in which the medium level corrosion has occurred and the sample C in which the large level corrosion has occurred is somewhat large, The difference in the output value of the detection signal between the sample A in which corrosion has not occurred and the sample B in which medium-level corrosion has occurred is small. For this reason, it is difficult to diagnose accurately the degree of corrosion using only the output value of the detection signal.

  Further, as shown in FIG. 5, the difference in phase difference between sample B in which medium-level corrosion has occurred and sample C in which large-level corrosion has occurred is somewhat large. However, there is almost no difference in the phase difference between the sample B in which medium-level corrosion has occurred and the sample A in which no corrosion has occurred, and it is difficult to accurately detect the degree of corrosion.

  Next, the inventors have created a graph in which the relationship between the output values of a plurality of detection signals obtained each time the excitation coil 11 and the detection coil 12 move and the phase difference is mapped. FIG. 6 shows the results. The frequency is set between 3 [kHz] at which the difference between the output value of the detection signal and the difference between the phase differences is largest. As shown in the figure, the difference between the output values of the detection signals is large to some extent between sample A in which no corrosion has occurred and sample B in which medium-level corrosion has occurred. Therefore, the diagnosis can be made by distinguishing the two. On the other hand, the sample B in which the medium level corrosion has occurred and the sample C in which the large level corrosion has occurred have a certain difference in the phase difference. Therefore, by detecting the corrosion based on both the output value of the detection signal and the phase difference, it is possible to accurately detect the degree of corrosion.

  Next, the operation of the deterioration detection device 1 described above in brief will be described with reference to FIG. First, a worker inserts the electric wire 2 into a main body (not shown) to which the excitation coil 11 and the detection coil 12 are attached. Thereby, as shown in FIGS. 2 and 3, the excitation coil 11 and the detection coil 12 can be arranged on the electric wire 2. Next, when the operator operates an operation unit (not shown), the control unit 17 executes the processing shown in FIG.

  First, the control unit 17 turns on the AC power supply 13 (step S1). As a result, an excitation signal flows through the excitation coil 11 and an eddy current is induced on the conductor surface of the current 2. In the present embodiment, the frequency of the excitation signal is set to 1 to 100 kHz. As shown in FIGS. 4 and 5, by setting the frequency of the excitation signal to 1 to 100 kHz, the output difference of the detection signal between the sample A and the sample B is increased, and the phase difference between the sample B and the sample C is increased. Can be increased. However, the frequency at which the difference between the output value and the phase difference becomes large varies depending on the design of the excitation coil 11 and the detection coil 12, and is not limited to this.

  Next, the control unit 17 captures the detection signal output from the detection unit 14 (Step S2). Next, the control unit 17 obtains the output value and the phase difference of the captured detection signal and stores them in a storage unit such as a RAM (step S3).

  Thereafter, the control unit 17 determines whether or not a termination operation has been performed by the worker (Step S4). If the end operation has not been performed (N in step S4), the control unit 17 drives the motor 151 to move the excitation coil 11 and the detection coil 12 by a predetermined distance along the longitudinal direction D1 of the electric wire 2 ( Step S5), and return to step S2. Accordingly, the output value and the phase difference of the detection signal are stored in the RAM every time the excitation coil 11 and the detection coil 12 move.

  On the other hand, if the end operation has been performed (Y in step S4), the control unit 17 creates a graph mapping the relationship between the output values of the plurality of detection signals stored in the RAM and the phase difference. Is displayed on the display unit 16 (step S5), and the process ends. The operator diagnoses the corrosion of the electric wire 2 from the graph displayed on the display unit 16.

  As shown in FIG. 6, the control unit 17 displays a region showing a large level of corrosion, a region showing a medium level of corrosion, and a region without corrosion on a graph so as to be distinguishable. Specifically, a boundary line L2 is displayed at a boundary between a region showing a large level of corrosion and a region showing a medium level of corrosion, and a boundary line L1 is displayed at a boundary between a region showing a medium level of corrosion and a region showing no corrosion. are doing. The worker can detect the corrosion level based on the area where the point plotted on the graph is located.

  Note that the above-mentioned region showing a large level of corrosion, the region showing a medium level of corrosion, and the region without corrosion are scanned by the exciting coil 11 and the detection coil 12 on the wire 2 on which no corrosion has occurred in advance. It is determined based on the detection signal at that time.

  According to the above-described embodiment, the control unit 17 causes an excitation signal to flow through the excitation coil 11 to generate an eddy current on the electric wire 2, and causes the detection coil 12 to output a detection signal corresponding to the eddy current. Then, the worker detects the corrosion level of the electric wire 2 based on the output of the detection signal plotted on the graph displayed on the display unit 16 and the phase difference between the excitation signal and the detection signal. As described above, since the corrosion level of the electric wire 2 is detected based on both the magnitude of the detection signal and the phase difference between the excitation signal and the detection signal, the detection accuracy of the corrosion level can be improved. Further, since the degree of corrosion of the electric wire 2 is known, the life of the electric wire 2 is known, and the management of the electric wire 2 becomes easy.

  According to the above-described embodiment, the control unit 17 moves the excitation coil 11 and the detection coil 12 along the longitudinal direction D1 of the electric wire 2 and outputs a detection signal of the detection signal obtained each time the excitation coil 11 and the detection coil 12 move. The output value, the excitation signal and the phase difference between the excitation signals are plotted and displayed on a graph. As described above, by scanning the electric wire 2 using the excitation coil 11 and the detection coil 12, it is possible to detect corrosion of the entire electric wire 2.

  In addition, as shown in FIG. 6, by displaying a graph in which the relationship between the output value of the detection signal, the excitation signal, and the phase difference between the excitation signals is mapped, the degree of corrosion can be visually easily understood. Easy to detect corrosion.

  In addition, according to the above-described embodiment, the control unit 17 displays the graph indicating the relationship between the output value of the detection signal, the excitation signal, and the phase difference between the excitation signals, but is not limited thereto. Absent. The control unit 17 may simply display the output value of the detection signal, the excitation signal, and the phase difference between the excitation signals.

  According to the above-described embodiment, the worker detects the corrosion level by looking at the graph showing the relationship between the output value of the detection signal, the excitation signal, and the phase difference between the excitation signals. It is not limited. The control unit 17 may function as a detection unit, determine the corrosion state from the output value of the detection signal, the excitation signal and the phase difference between the excitation signals, and display the fact on the display unit 16.

  Further, according to the above-described embodiment, the excitation coil 11 and the detection coil 12 are moved to move the excitation coil 11 and the detection coil 12 with respect to the electric wire 2, but the present invention is not limited to this. The excitation coil 11 and the detection coil 12 may be moved with respect to the electric wire 2 by moving the electric wire 2 along the longitudinal direction D1.

  Further, according to the above-described embodiment, the deterioration of the conductor of the electric wire 2 is detected, but the present invention is not limited to this. The conductor may not be the conductor of the electric wire 2.

  Note that the present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.

2 Electric wire 11 Excitation coil 12 Detection coil 16 Display unit (output unit)
17 control unit (detection unit)
22 conductor D1 longitudinal direction

Claims (5)

A deterioration detection method for detecting a deterioration state of a conductor,
An output step of causing an excitation signal to flow through an excitation coil to generate an eddy current on the conductor, and using a detection coil to output a detection signal corresponding to the eddy current;
A deterioration detection method for detecting a deterioration state of the conductor based on a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal. The conductor is composed of a conductor of an electric wire,
In the output step, the exciting coil and the detecting coil are moved along the longitudinal direction with respect to the conductor,
2. The detection step according to claim 1, wherein the deterioration state of the conductor is detected based on the magnitude of the detection signal obtained each time the excitation coil and the detection coil move, and the phase difference. The deterioration detection method described in 1.   In the detection step, a graph is created in which the relationship between the magnitude of the detection signal obtained each time the excitation coil and the detection coil moves and the phase difference is mapped, and the deterioration of the conductor is determined based on the graph. 3. The method according to claim 2, wherein the state is detected. An excitation coil for generating an eddy current in the conductor, and a detection coil for outputting a detection signal according to the eddy current, a deterioration detection device for detecting a deterioration state of the conductor,
A deterioration detection device, further comprising an output unit that outputs a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal. An excitation coil for generating an eddy current in the conductor, and a detection coil for outputting a detection signal according to the eddy current, a deterioration detection device for detecting a deterioration state of the conductor,
The degradation detection device further comprising a detection unit that detects the conductor state based on a magnitude of the detection signal and a phase difference between the excitation signal and the detection signal.

Images