JP2799587B2 - Wire inspection equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric wire flaw detection device for inspecting an outer surface of an electric wire, a flaw of a wire, or the like.

(Conventional technology) For example, overhead lines such as ACSR are often laid via mountainous areas, and damage by lightning is occurring frequently. The degree of the damage varies from a slight degree to a degree that the wire cannot be left as it is, such as a broken wire. Breakage of the wire may cause corona discharge, lower the tensile strength of the overhead wire, and cause a major accident such as breakage.
Therefore, conventionally, an electric wire flaw detection device for automatically flaw-detecting an electric wire such as an overhead wire over its entire length has been developed.

 FIG. 5 shows a schematic configuration diagram of a conventional electric wire flaw detector.

In this figure, this device has a pair of drive wheels 3 so that it can run on the electric wire 1 by itself.
The arrow 10a is drawn on the electric wire 1 by the driving unit 4 such as a motor.
It is driven to travel in the direction.

In addition, several flaw detection coils 5 are provided inside the apparatus, and are positioned by guide wheels 6 that maintain a predetermined distance from the electric wire 1. This guide wheel 6
Is provided so as to trace the outer peripheral surface of the electric wire 1. The coil holder 7 supporting each of the flaw detection coils 5 includes:
An arrow 10b is attached to the frame 2 of the apparatus by using the hanging metal fittings 8.
Hanged movably in the direction. This hanging bracket 8 is
The vertical vibration of the coil holder 7 is absorbed, and together with the guide wheel 6, the flaw detecting coil 5 acts to maintain the distance between the coil 1 and the electric wire 1 at a predetermined distance.

The control unit 9 processes the output signal of the flaw detection coil 5 or outputs a predetermined drive signal to the drive unit 4.
Is provided. On the other hand, on the rear side of the frame 2,
A camera 11 and a mirror 12 are arranged so as to sandwich the electric wire 1.

 The above device operates as follows.

First, the driving unit 4 rotates the driving wheel 3 and the frame 2
Along the electric wire 1 at a constant speed in the direction of the arrow 10a. While the frame 2 is running, the flaw detection coil 5
While maintaining a predetermined distance between the wire 1 and the
Flaw detection on the outer surface of the If a certain level of flaw detection is detected on the surface of the electric wire 1, the control unit 9 records the detection signal, activates the camera 11, and photographs the outer surface of the electric wire 1. The mirror 12 is provided for photographing a portion on the back side of the electric wire 1 which cannot be photographed directly by the camera 11.

(Problems to be Solved by the Invention) The flaw detection coil generally detects a flaw detection signal by capturing a change in eddy current. In that case, in order to increase the detection sensitivity, two detection coils are connected to two sides of the AC bridge, and when there is a flaw on the wire surface, the magnetic flux of the eddy current flowing on the wire surface is received by the two detection coils. The position and size of the flaw are detected by capturing the imbalance in the induced current.

If the wire surface is uniformly smooth, a constant AC voltage is always induced in the flaw detection coil, and the output does not change. In addition, the detection sensitivity of the flaw varies depending on the opposing angle between the flaw detection coil and the surface of the electric wire as the object to be measured, and the traveling speed on the electric wire of the electric wire flaw detector.

For example, as shown in FIG. 6, between two towers 13,
It is assumed that the electric wire 1 is installed with an appropriate dip. When the flaw detector 14 travels on the electric wire 1, the waveform of the flaw detection signal output from the flaw detection coil differs between an uphill slope and a downhill slope even for a flaw having the same size. This is because the traveling speed of the flaw detector 14 itself changes depending on the gradient of the electric wire 1. However, this causes a problem that the true value of the flaw detection signal cannot be measured, and the size of the flaw cannot be analyzed from only the flaw detection signal.

Further, as described in FIG.
When the camera detects a flaw on the surface of the electric wire 1, the camera 11 operates to photograph the flaw. This is because of a delay control circuit that operates the camera 11 a fixed time after the flaw detection coil 5 detects the flaw. Based on behavior. Therefore, for example, if the traveling speed fluctuates remarkably, there arises an inconvenience that a flaw on the surface of the electric wire 1 to be originally photographed does not enter the field of view of the camera. However, even if the traveling speed of the flaw detector is set unconditionally to an appropriate constant speed, a clear flaw detection signal may not be obtained.

The present invention has been made by paying attention to the above points, and a wire flaw detection apparatus capable of stably detecting a flaw detection signal with high sensitivity and obtaining a flaw detection signal sufficient to analyze a true flaw size and the like. The purpose is to provide.

(Means for Solving the Problems) The present invention provides a traveling machine traveling on an electric wire, moves along the electric wire together with the traveling machine, detects damage to the electric wire, and outputs a signal including a flaw detection signal. An electric wire flaw detection device comprising: a flaw detection coil; a filter circuit for removing noise included in an output signal of the flaw detection coil; and a flaw detection signal processing circuit for processing the flaw detection signal output from the filter circuit. Traveling speed control means for causing the traveling machine to travel at a constant speed in accordance with the bandwidth of the vehicle, and the flaw detection signal to be input to the flaw detection signal processing circuit in accordance with the traveling speed of the traveling machine at a constant signal level. And a correction circuit for performing correction.

(Effect) The above-described wire flaw detection apparatus reduces noise by causing a traveling machine to travel at a constant speed to output a signal output from a flaw detection coil and having a certain frequency band depending on the traveling speed through a filter circuit. Remove and remove. If the traveling speed differs, the setting of the filter circuit for removing noise also differs. Therefore, the traveling speed that maximizes the noise removal characteristic of this filter circuit is set, and the speed control means is operated. On the other hand, since the level of the flaw detection signal fluctuates according to the traveling speed, the level of the flaw detection signal is corrected by the correction circuit in accordance with the traveling speed, and a flaw detection signal of a constant level is always obtained.

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of an electric wire flaw detector according to the present invention.

The apparatus shown in the figure is composed of a traveling machine 10 traveling on the electric wire 1 and an electric wire 1.
Flaw detection coil 5 disposed opposite to the vehicle, and traveling speed control means 20
, A filter circuit 30, and a flaw detection signal processing circuit 40.

The traveling machine 10 travels on the electric wire 1 by the driving wheels 3. The traveling machine 10 may have the flaw detection coil 5 mounted thereon, or may have a configuration for towing a device on which the flaw detection coil 5 is separately mounted.

The traveling speed control means 20 includes an F / V converter 21, a reference speed setting device 22, a comparison amplifier 23, and a motor driver 24.

The drive wheel 3 is provided with a motor via a gear or the like on its rotating shaft.
A rotary encoder 26 for detecting rotation of the drive wheel 3 is provided.

The F / V converter 21 of the traveling speed control means 20 is a circuit which receives the output signal of the rotary encoder 26 and outputs a voltage proportional to the rotation speed of the drive wheels 3, that is, the traveling speed of the traveling machine 10. This circuit comprises a known frequency / voltage conversion circuit.

The reference speed setting device 22 includes a volume for setting the speed at which the traveling machine 10 travels in advance, a power supply voltage is applied to the volume, and a voltage corresponding to the reference speed is supplied to the comparison amplifier 23. Is output.

The comparison amplifier 23 is a circuit that receives the output of the F / V converter 21 and the output of the reference speed setter 22, amplifies and outputs the difference signal between the two. The motor 25 is connected to the output side of the comparison amplifier 23 via a motor driver 24. The motor driver 24 includes a known servo circuit or the like that sets the rotation speed of the motor 25 according to the output signal output from the comparison amplifier 23 and drives the motor 25 at a constant reference speed.

On the other hand, the filter circuit 30 includes an amplifier circuit 31 and a bandpass filter.
32.

The output signal of the flaw detection coil 5 is input to the amplification circuit 31 and is amplified. The bandpass filter 32 is a circuit formed of a coil, a capacitor, and the like for removing noise from the output signal of the flaw detection coil 5.

The flaw detection signal processing circuit 40 includes a phase detection circuit 41 and a recording unit 42.
It is composed of

The phase detection circuit 41 is a circuit that detects the output signal of the filter circuit 30 and outputs the detected signal to the recording unit 42. The recording unit 42 is a circuit that includes a pen recorder, a tape recorder, and the like, and that records a flaw detection signal.

 The above device operates as follows.

FIG. 2 is a graph showing characteristics of the bandpass filter 32 of FIG. The horizontal axis in the figure indicates the signal frequency, and the vertical axis indicates the output signal level.

That is, the bandpass filter 32 has, for example, a center frequency of about 30.
Set the Hz and bandwidth to about 10 to 50 Hz. In addition, a notch filter having a center frequency of 50 Hz is built in to remove noise based on the power supply frequency, and a bandpass filter having a characteristic as shown in FIG. 2 as a whole is provided.

The reason why the center frequency of the bandpass filter is set to 30 Hz is as follows.

In FIG. 1, the lateral width L of the flaw detection coil 5 facing the electric wire 1 is, for example, 12 mm, and the traveling speed of the traveling machine 10 is 20 m / min.
And In this case, the traveling machine travels 33.3 cm per second, and if this is divided by the above 12 mm, V / L = 30 Hz, that is, if the sampling frequency of the output signal of the flaw detection coil is 30 Hz, the flaw detection operation on the wire surface is good. You can see that it can be done.

Therefore, if a signal centered on a frequency of 30 Hz is extracted by the bandpass filter 32 and is output to the flaw detection signal processing circuit 40, other unnecessary noise is removed, so-called
A signal having a high S / N ratio is processed in the flaw detection signal processing circuit 40.

FIG. 3 shows an example of the flaw detection signal thus obtained. The graph in the figure is a graph in which the horizontal axis represents time, and the vertical axis represents the output signal level of the flaw detection signal.

As shown in the figure, when the flaw detection signal S1 is obtained at a certain traveling speed and the same flaw is detected by running the traveling machine at a lower speed, a flaw detection signal S2 having a low level and a widened width is obtained. In order to determine the size of the flaw by comparing with a fixed reference level, the traveling speed of the traveling machine must always be set to a constant value along the reference level.

However, the traveling speed that maximizes the noise removal characteristics of the filter circuit differs depending on the type and size of the flaw detection coil 5 and other conditions. Therefore, the operator needs to adjust the reference speed setting device 22 to the optimal value in advance. The speed is not always in accordance with the reference level. Therefore, conversion of the flaw detection signal may be required.

Therefore, for example, it is preferable to add a circuit as shown in FIG.

The circuit shown in the figure is configured such that a multiplier 43 is inserted between the phase detection circuit 41 and the recording unit 42 shown in FIG. 1 and the output signal of the F / V converter 21 is input to this. Things.

That is, F / F is added to the flaw detection signal output from the phase detection circuit 41.
The voltage signal corresponding to the traveling speed output from the V converter 21 is multiplied. That is, when the voltage output from the F / V converter 21 is smaller than the voltage obtained by the reference traveling speed, the multiplier 43 corrects the flaw detection signal in a direction to increase the level, and conversely, from the F / V converter 21. When the output voltage is large, the flaw detection signal is corrected in a direction to reduce the level. If the result is output to the recording unit 42, a constant flaw detection signal is output to the recording unit 42 without depending on the traveling speed. Thus, analysis including the waveform of the flaw detection signal can be easily performed.

(Effect of the Invention) The electric wire flaw detection apparatus of the present invention described above allows the traveling machine to run at a running speed that maximizes the noise removal characteristics of the filter circuit that processes the flaw detection signal output from the flaw detection coil and keeps the flaw detection signal constant. Since the level is corrected to a level, a clear flaw detection signal from which noise has been removed can be obtained, and high-precision analysis can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the electric wire flaw detector of the present invention, FIG. 2 is a graph showing characteristics of the bandpass filter 32,
FIG. 3 is a graph showing examples of flaw detection signals in various cases, and FIG.
FIG. 1 is a block diagram showing an embodiment of a circuit to be added to the apparatus of the present invention. FIG. 5 is a schematic view showing a configuration of a conventional flaw detector.
FIG. 6 is an explanatory view showing the operation of the conventional flaw detector. 3 ... drive wheel, 5 ... flaw detection coil, 10 ... traveling machine, 20
… Running speed control means, 21… F / V converter, 22…
Reference speed setting device, 23 ... Comparison amplifier, 24 ... Motor driver, 25 ... Motor, 30 ... Filter circuit, 31 ... Amplification circuit, 32 ... Band filter, 40 ... Flaw detection signal processing circuit,
41: Phase detection circuit, 42: Recording unit.

Claims (1)

(57) [Claims] 1. A traveling machine that travels on an electric wire, a flaw detection coil that moves along with the traveling wire together with the traveling machine, detects damage to the electric wire, and outputs a signal including a flaw detection signal. An electric wire flaw detector comprising: a filter circuit that removes noise included in an output signal; and a flaw detection signal processing circuit that performs signal processing on the flaw detection signal output from the filter circuit, wherein the wire flaw detection device corresponds to a bandwidth of the filter circuit. Traveling speed control means for traveling the traveling machine at a constant speed; and a correction circuit for compensating the flaw detection signal to be input to the flaw detection signal processing circuit to a constant signal level in accordance with the traveling speed of the traveling machine. An electric wire flaw detector.