JP7204291B2 - Deterioration detection method and deterioration detection device - Google Patents

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 aims at diagnosing rust (hereinafter referred to as corrosion) in electric wires connected to bushings of transformers. An electric wire is clamped between a clamp head containing an excitation coil and a detection coil, an excitation current is passed through the excitation coil to generate an eddy current in the wire, and corrosion is diagnosed based on the detection output corresponding to the eddy current output from the detection coil. are doing.

However, the conventional anomaly detection device has a problem that it is only accurate enough to detect the presence or absence of corrosion and cannot detect how much corrosion (deterioration) has occurred.

JP 2007-271607 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide a deterioration detection method and a deterioration detection device that improve the detection accuracy of a deterioration state.

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

Further, the conductor is a conductor of an electric wire, the excitation coil and the detection coil are moved along the longitudinal direction of the conductor in the output step, and the excitation coil and the detection coil are moved in the detection step. The deteriorated 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.

Further, in the detecting step, a graph 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 is created, and based on the graph, the conductor is 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 corresponding to the eddy current, wherein the deterioration detection device detects deterioration of the conductor. The deterioration detection device for detecting a state is characterized by further comprising an output section for outputting the magnitude of the detection signal and the 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 corresponding to the eddy current, wherein the deterioration detection device detects deterioration of the conductor. A deterioration detection device for detecting a state, further comprising a detection unit for detecting the state of the conductor based on the magnitude of the detection signal and the phase difference between the excitation signal and the detection signal. .

According to the above-described 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, it is possible to improve the detection accuracy of the deterioration state. .

1 is a block diagram showing an embodiment of a deterioration detection device that implements the deterioration detection method of the present invention; FIG. FIG. 2 is a front view showing the arrangement of electric wires, excitation coils, and detection coils that constitute the deterioration detection device shown in FIG. 1 ; FIG. 2 is a side view showing the arrangement of electric wires, excitation coils, and detection coils that constitute the deterioration detection device shown in FIG. 1 ; 4 is a graph showing frequency characteristics of output values of detection signals for a reference sample and samples A to G; 5 is a graph showing frequency characteristics of phase differences of detection signals and excitation signals for a reference sample and samples A to G; 5 is a graph showing the relationship between the output of detection signals for a reference sample and samples A to G and the phase difference between the detection signal and the excitation signal. 2 is a flow chart showing a processing procedure of a control unit shown in FIG. 1;

An embodiment of the present invention will be described below with reference to FIG. The deterioration detection device 1 shown in the figure is a device for detecting the 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 made by twisting a plurality of strands 21 and a coating 23 covering the conductor 22 .

As shown in FIG. 1, the deterioration detection device 1 includes an excitation coil 11, a detection coil 12, an AC power supply 13, a detection section 14, a coil movement section 15, a display section 16, and a control section 17. I have it.

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

The coil moving section 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 the electric wire 2 is passed through, and a motor shown in FIG. 1 for moving this main body along the longitudinal direction D1. 151 and .

The main body (not shown) is provided with a rotating body such as a traveling roller inside thereof, and is movable with respect to the electric wire 2 along the longitudinal direction D1. As shown in FIG. 2, the excitation coil 11 and the detection coil 12 are attached to the main body so that the central axis A thereof extends along the radial direction D2 of the electric wire 2. As shown in FIG. As shown in FIG. 3, the excitation coil 11 and the detection coil 12 are arranged along the longitudinal direction D1 and partially overlapped.

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

The control unit 17 is composed of a microcomputer containing a CPU, a ROM, a RAM, etc., and controls the deterioration detection device 1 as a whole. 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 a 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 the output value and the phase difference of the detection signal detected each time the excitation coil 11 and the detection coil 12 move. Further, 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 the deterioration detection method using the deterioration detection device 1 will be described with reference to FIGS. 4 to 6. FIG. Using the deterioration detection device 1 described above, an excitation signal of 1 kHz to 100 kHz is passed through the excitation coil 11 for the electric wire 2 of the samples A to C, and the output value and phase difference of the detection signal of the detection coil 12 are measured. are shown in FIGS. As the excitation coil 11 and the detection coil 12, those having an inner diameter of 30 [mm] and the number of turns of 300 [T] were used.

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

As shown in FIGS. 4 and 5, the corroded electric wire 2 has a lower detection signal output value and a phase delay than the uncorroded electric wire 2 . The reason why the output value of the detection signal decreases is as follows. The corroded electric wire 2 has a higher resistance on the surface of the conductor 22 than the uncorroded electric wire 2, and the eddy current generated on the surface of the conductor 22 is suppressed, thereby reducing the output value. The reason for the phase delay is as follows. When corrosion occurs on the surface of the wires 21, the corrosion between the wires 21 (electrodes) acts as an insulator, and the wires 21 act as pseudo capacitors. A phase delay occurs due to the capacitive component of this capacitor.

As shown in FIG. 4, at about 10 [kHz] or less, the difference in the output value of the detection signal between the sample A, in which no corrosion occurs, and the sample B, in which a medium level of corrosion occurs, is somewhat large. . However, the difference in the output value of the detection signal between the sample B in which the medium level of corrosion has occurred and the sample C in which the large level of corrosion has occurred is small. At about 10 [kHz] or higher, on the contrary, the difference in the output value of the detection signal between the sample B, in which medium level corrosion occurs, and the sample C, in which large level corrosion occurs, is large to some extent. The difference in the output value of the detection signal between the sample A with no corrosion and the sample B with medium level corrosion is small. Therefore, it is difficult to accurately diagnose the degree of corrosion based only on the output value of the detection signal.

Further, as shown in FIG. 5, the difference in phase difference between the sample B in which the medium level of corrosion has occurred and the sample C in which the large level of corrosion has occurred is large to some extent. However, there is almost no difference in phase difference between the sample B in which a medium level of 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 created a graph mapping 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. The results are shown in FIG. Note that the frequency is set between 3 [kHz] where the difference in the output values and the difference in the phase difference of the detection signals are maximized. As shown in the figure, the difference in the output values of the detection signals between the sample A with no corrosion and the sample B with medium level corrosion is large to some extent. Therefore, both can be distinguished and diagnosed. On the other hand, there is a certain phase difference between the sample B in which a medium level of corrosion has occurred and the sample C in which a large level of corrosion has occurred, so that both can be diagnosed separately. Therefore, by detecting corrosion based on both the output value and the phase difference of the detection signal, even the degree of corrosion can be accurately detected.

Next, the operation of the deterioration detection device 1 outlined above will be described with reference to FIG. First, an operator inserts the electric wire 2 into the main body (not shown) to which the excitation coil 11 and the detection coil 12 are attached. Thereby, the excitation coil 11 and the detection coil 12 can be arranged on the wire 2 as shown in FIGS. Next, when the worker 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 surface of the conductor of the current 2 . In this embodiment, the frequency of the excitation signal is set to 1-100 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 sample A and sample B is increased, and the phase difference between sample B and sample C is increased. can be increased. However, since the frequency at which the difference in output value and phase difference becomes large varies according to the design of the excitation coil 11 and the detection coil 12, this is not the case.

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

After that, the control unit 17 determines whether or not the operator has performed an end operation (step S4). If the termination 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 along the longitudinal direction D1 of the electric wire 2 by a predetermined distance ( Step S5) and return to step S2. As a result, the RAM stores the output value and phase difference of the detection signal each 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 worker diagnoses the corrosion of the electric wire 2 from the graph displayed on the display unit 16. FIG.

As shown in FIG. 6, the control unit 17 displays a region showing high-level corrosion, a region showing medium-level corrosion, and a region showing no corrosion so that they can be identified on the graph. Specifically, a boundary line L2 is displayed at the boundary between the region showing high level corrosion and the region showing medium level corrosion, and a boundary line L1 is shown at the boundary between the region showing medium level corrosion and the region showing no corrosion. are doing. The operator can detect the corrosion level by where the points plotted on the graph are located.

The above-described high-level corrosion region, medium-level corrosion region, and non-corrosion region are determined by scanning the electric wire 2 in which corrosion has not occurred in advance by the excitation coil 11 and the detection coil 12. and is determined based on the detection signal at that time.

According to the above-described embodiment, the control unit 17 causes the excitation coil 11 to pass an excitation signal 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. A 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. In this manner, 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, so the detection accuracy of the corrosion level can be improved. Moreover, since the degree of corrosion of the electric wire 2 can be known, the life of the electric wire 2 can be 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 changes 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. Thus, by scanning the electric wire 2 using the excitation coil 11 and the detection coil 12, corrosion detection of the entire electric wire 2 can be performed.

Further, as shown in FIG. 6, by displaying a graph mapping the relationship between the output value of the detection signal, the excitation signal, and the phase difference between the excitation signal, the degree of corrosion can be visually understood. Easy to detect corrosion.

According to the above-described embodiment, the control unit 17 displays a graph showing the relationship between the output value of the detection signal, the excitation signal, and the phase difference between the excitation signal. 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.

Further, 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 of the excitation signal. 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 and the phase difference between the excitation signal and the excitation signal, and display the result 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 electric wire 2 may be moved along the longitudinal direction D<b>1 to move the exciting coil 11 and the detection coil 12 with respect to the electric wire 2 .

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

It should be noted that the present invention is not limited to the above embodiments. 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 section (output section)
17 control unit (detection unit)
22 conductor D1 longitudinal direction

Claims (2)

A deterioration detection method for detecting a deterioration state of a conductor, comprising:
an output step of applying an excitation signal to 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 detection step of detecting the deterioration state of the conductor based on the magnitude of the detection signal and the 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, moving the excitation coil and the detection coil along the longitudinal direction with respect to the conductor;
In the detection step, a graph mapping the relationship between the magnitude of the detection signal obtained each time the excitation coil and the detection coil move and the phase difference is created, and the graph and the graph are divided into three A deterioration detection method, wherein the deterioration state of the conductor is detected based on two boundary lines dividing the area. A deterioration detection device for detecting the deterioration state of the conductor, comprising an excitation coil for generating an eddy current in the conductor and a detection coil for outputting a detection signal corresponding to the eddy current,
a detection unit that detects the deterioration state of the conductor based on the magnitude of the detection signal and the phase difference between the excitation signal flowing through the excitation coil and the detection signal ;
a coil moving unit that moves the excitation coil and the detection coil along the longitudinal direction of the conductor ;
the conductor is composed of a conductor of an electric wire ,
The detection unit creates a graph mapping the relationship between the magnitude of the detection signal obtained each time the excitation coil and the detection coil move and the phase difference, and divides the graph and the graph into three 1. A deterioration detection device, wherein the deterioration state of the conductor is detected based on two boundary lines dividing the area.

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