JP2535417B2 - Defective insulator detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention reliably, swiftly, and safely detects a defective portion such as a crack in an insulator body of a suspension insulator that supports a power transmission line. The present invention relates to a defective insulator detection method that can be performed.

[Prior Art] Conventionally, as a detector for detecting a defective suspension insulator of a suspension insulator series for a transmission line, a voltage shared by each suspension insulator is measured to detect a defective insulator (Japanese Patent Publication No. 40-3057 of the same applicant). Issue).

This defective insulator detector is provided with a pair of contact rods that contact the upper and lower ends of the suspended insulator at the tip of the insulating rod, discharge the gap of the detector according to the voltage shared by the insulator, and determine whether the neon lamp blinks. It is supposed to make a decision.

Further, the applicant of the present invention has disclosed that
The detection method of 62-166471 was proposed. This is to irradiate the insulator with a laser beam from a laser generator to give a mechanical impact to vibrate the insulator, and to irradiate a vibration detection laser on the porcelain surface of the insulator by a laser transmitting / receiving device for detecting this vibration. Then, the reflected laser is received by the laser transmitter / receiver, and this signal is subjected to frequency analysis by a frequency analyzer, and the defective insulator is compared by comparing the vibration mode of the normal insulator with the vibration mode of the defective insulator. Is detected.

[Problems to be Solved by the Invention] However, the former defective insulator detector has a high risk because it is necessary to work on a steel tower when judging whether the suspended insulator in use is good or bad, and Since a long insulating rod is used, there is a problem that the workability is poor and the efficiency of judging the quality is extremely low.

Further, in the latter method of detecting a defective insulator, even if the vibration mode of a normal insulator and the vibration mode of a defective insulator are actually compared, it is difficult to determine the quality of the insulator. That is, it was difficult to detect the crack of the insulator from the change of the vibration because the change of the vibration mode by the frequency spectrum analysis is only a subtle difference accompanied by a slight frequency shift. . Further, in detail, output waveforms from the accelerometer vibration detector obtained when the normal insulator and the defective insulator are irradiated with the CO ₂ laser light are shown in FIGS. 7 and 8. (Note that the laser output at this time is approximately 2.7 J.) As is clear from both figures, there is no noticeable difference in the waveforms of the two, and defective insulators are detected from the mere difference in the waveforms by frequency spectrum analysis. Is quite difficult.

As described above, the object of the present invention is to make good use of the advantages of the frequency spectrum analysis conventionally performed as described above, and to further develop it, so that the quality of the normal insulator and the defective insulator can be surely and quickly determined. It is to provide a method of detecting an insulator.

[Means for Solving the Problems] In order to achieve the above object, the present invention irradiates a laser from a laser generator to an insulator to give a mechanical impact to vibrate the insulator and to detect the vibration. Irradiation of a measuring laser on the porcelain surface of the insulator by the transmitter-receiver to reflect on the same porcelain surface, the reflected laser is received by the laser transmitter-receiver, the peak value of a specific frequency in a predetermined time zone by the frequency spectrum analyzer. , The frequency spectrum analysis of the vibration mode in a predetermined frequency band (f _{0 to} f ₁ ) is performed, and the same time as the predetermined time zone for the reference frequency spectrum {S ₀ (f)} of the normal insulator obtained by this method. Residual {S of slight deviation of peak value of measured frequency spectrum {S (f)} of the insulator to be detected obtained in the band
The square of (f) −S ₀ (f)} is calculated by a calculation device, and the integrated value (V) of the square of the residual of the detected insulator is compared with a preset set value (Vo). The method is to determine whether the detected insulator is normal or defective.

[Operation] According to the present invention, the residual between the reference frequency spectrum of the normal insulator and the measured frequency spectrum of the detected insulator is calculated by the arithmetic device, and the integrated value of the square of the residual of the detected insulator and the preset value are set. Is compared to determine whether the insulator is normal or defective, so that the determination can be performed reliably and quickly.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

As shown in FIG. 3, the suspension armature 4 supporting the power transmission line 3 is suspended from the support arm 2 of the steel tower 1. This suspension insulator string 4 is constituted by connecting a large number of suspension insulators 5 shown in FIG. 2 in series. The suspension insulator 5 is composed of an insulator body 6 and a cap metal fitting 7 cemented to the upper portion thereof and a pin metal fitting 8 cemented to the lower portion thereof.

On the other hand, a pulse laser generator 11 as a laser generator for insulator vibration for giving a mechanical impact to the suspension insulator 5 is installed at a stable position on the ground G, and a laser beam is applied to the porcelain surface 6a of the insulator body 6. By irradiating, the suspension insulator 5
To be able to vibrate. From the laser generator 11
When the insulator surface is irradiated with CO ₂ laser light (λ = 10.6 μm, output to several J), an impact is generated on the irradiated surface, which causes the insulator to vibrate.

Further, a He-Ne laser generator 12 is installed near the pulse laser generator 11 as a vibration detecting laser generator for detecting the vibration of the insulator by utilizing the interference of the laser. The laser generator 12 irradiates a He-Ne laser beam of λ = 0.64 μm and an output of several mW. In front of the laser generator 12, a beam splitter 13 for splitting the laser light emitted from the generator 12 into two is disposed. Then, the laser light that has proceeded straight from the beam splitter 13 is irradiated onto the surface of the suspension insulator 5, and then passes through the slide glass 14 as object reflected light to be input to the photodetector 15. (See the solid line in FIG. 2) On the other hand, the original laser light (reference light) split by the beam splitter 13 interferes with the object reflected light from the insulator due to the optical path difference. Since the reference light has a considerably higher light intensity than the object-reflected light, when the reference light and the object-reflected light are overlapped with each other, it is difficult to see the interference unless the light intensities are approximately the same. Therefore, after passing through the beam diffusing lens 16 that attenuates the light intensity, the glass slide 14 is transmitted straight through, similarly passes through the filter 17 to attenuate the light intensity, is reflected by the Al mirror 18, and is again the film. The slide glass 14 was guided through 17 and was reflected by the slide glass 14 to coincide with the object-reflected light to generate interference light. The interference fringes of this interference light are detected by the photodetector 15 (photomultiplier tube PM: Photomultip
lier) and convert it to an electrical signal.

The photodetector 15 detects this movement because the interference fringes also move when the suspension insulator is vibrated. Fourth
The figure shows the change in the output detected by the photodetector 15.

The cause of the movement of the interference fringes is that when the suspension insulator 5 is vibrated, the optical path difference between the reference light and the object reflected light changes.

Further, a digital storage oscilloscope 20 is connected to the photodetector 15 to record the output. Further, the oscilloscope 20 is also provided with a mechanism for performing frequency analysis by Fast Fourier Transform (FFT). An analysis device 21 is connected to process the frequency-analyzed data, and a speaker 22 as a notification device is connected to the frequency analysis device 21.

Next, the operation of the defective insulator detecting device configured as described above will be described.

The porcelain surface 6a of the suspension insulator 5 is irradiated with laser light from the pulse laser generator 11 to give a mechanical shock to vibrate the suspension insulator 5. Then, the movement of the interference fringes is detected by the photodetector 15 and is converted into a voltage waveform signal as shown in FIG. When the electric signal of this PM output was recorded and heard by the ear, it was very similar to the timbre and afterglow that was heard directly when the sample was actually hit, so the vibration during laser beam irradiation hit the insulator. It is thought to correspond to the sound that is sometimes heard directly in the ear.

Next, the PM output is digital storage oscilloscope
Recorded by 20 and analyzed frequency spectrum,
A frequency spectrum is obtained as shown in FIGS. As is apparent from FIGS. 5A to 5D, various frequency components are included in the signal for 1 to 31 ms after laser light irradiation, but as time passes, the material of the sample It can be seen that it vibrates at the frequency of the eigenmode determined by the shape. PM in FIGS. 5 (a) to (c)
Comparing the output frequency spectrum, 2.2KHz, 4.4KHz
The vibration mode of is well understood, and the timbre and afterglow of the sound when listening to the PM output recording is considered to be a signal of this frequency. Then, as shown in FIG.
At 60 ms, this vibration is greatly attenuated and does not appear in the PM output.

Next, from the frequency spectra shown in FIGS. 5 (a) to 5 (d), the deviation of the frequency spectra between the normal insulator and the defective insulator is analyzed by the analyzer 21 for the peak of the spectrum of 4.4 KHz in this embodiment as follows. And analyze.

First, as shown in FIG. 1 (a), after irradiating laser light as a time period in which the normal insulator is vibrating in its eigenmode, a period of 150 to 180 ms for 30 ms is selected, and the frequency spectra of a plurality of normal suspension insulators are Using the peak value of about 4.4 KHz as the reference value, the frequency spectrum of the vibration mode in the given frequency band (f _{0 to} f ₁ ) in the given time zone is standardized, and the reference spectrum S of the normal insulator for making the average of them is determined. _It is stored as ₀ (f).

Further, the vibration spectrum of the detected insulator in the same time period and the same predetermined frequency band (f _{0 to} f ₁ ) as the reference spectrum S ₀ (f) of the normal insulator is subjected to frequency spectrum analysis,
It is stored as a measurement frequency spectrum S (f) as shown in FIG.

Further, an integral value V of the square of the residual [S (f) −S ₀ (f)] due to the deviation of the measured frequency spectrum S (f) of the detected insulator with respect to the reference spectrum S ₀ (f) is calculated.

V = ▲ ∫ ^f1 _f0 ▼ [S (f) -S ₀ (f)] ² df where f ₀ : 3.9KHz f ₁ : 4.9KHz This integrated value V is the peak value of the detected insulator and the peak of the normal insulator. If it deviates from the value even a little, it appears as a large value as shown in FIG. 1 (c). Therefore, by comparing the calculated integral value V with the preset setting value Vo,
It is possible to reliably and quickly determine whether the insulator is normal or defective.

By the way, in the above-mentioned example, the integral value V about the frequency spectrum near the peak value of 4.4 KHz of the frequency spectrum was measured before and after the cracks were formed in each of the detected insulators. In the figure, ◯ indicates the integrated value V of a normal insulator, and ● indicates the integrated value V of a cracked insulator. This shows that the deviation of the frequency spectrum S (f) of the insulator to be detected from the reference spectrum S ₀ (f) is larger after the crack is formed than before the crack is formed. As is apparent from FIG. 6, in this experiment, the set value Vo of the integral value V for discriminating the insulator with cracks is a relative value 12
It became a degree.

[Effects of the Invention] As described in detail above, the present invention can reliably and promptly detect whether a normal insulator or a defective insulator is present, and can be safely performed from a remote place even in a live state of a line.
Further, there is also an effect that automation of the insulator inspection in the factory line can be achieved.

[Brief description of drawings]

FIG. 1 shows the vibration modes of the normal insulator and the defective insulator detected by the defective insulator detecting device of the present invention and the residuals thereof.
2 is a schematic front view of the defective insulator detection device, FIG. 3 is a schematic front view of the defective insulator detection device arranged near the steel tower, and FIG. 4 is a PM output. A graph showing the relationship between (relative value) and time, FIG.
(D) is a graph showing the relationship between frequency and vibration intensity, FIG. 6 is an explanatory view showing the relationship between each sample and relative value (V), and FIGS. 7 and 8 are normal insulators showing a conventional example. FIG. 3 is a voltage waveform diagram of an output signal of a defective insulator. 11 ... Pulse laser generator, 12 ... He-Ne laser generator, 13
… Beam splitter, 14… Slide glass, 15… Photo detector (photomultiplier tube: PM), 16… Beam diffusion lens, 17…
Filter, 18… Al mirror, 20… Oscilloscope, 21… Analysis device.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A 64-10166 (JP, A) JP-A 64-80858 (JP, A) JP-A 54-102188 (JP, A)

Claims (1)

(57) [Claims] 1. An insulator is irradiated with a laser from a laser generator to give a mechanical shock to vibrate the insulator, and a laser transmitting / receiving device for detecting this vibration irradiates a measuring laser on the porcelain surface of the insulator. Then, it is reflected on the same porcelain surface, and the reflected laser is received by the laser transmitter / receiver,
Based on the peak value of a specific frequency in a predetermined time zone by a frequency spectrum analyzer, a predetermined frequency band (f ₀ ~
Frequency spectrum analysis of the vibration mode of f ₁ ), the reference frequency spectrum of normal insulator obtained by this method {S ₀ (f)}
The square of the residual {S (f) -S ₀ (f)} of the slight deviation of the peak value of the measured frequency spectrum {S (f)} of the detected insulator obtained in the same time zone as Is calculated by an arithmetic device, and the integrated value (V) of the square of the residual of the detected insulator is compared with a preset set value (Vo) to determine whether the detected insulator is normal or defective. A method for detecting a defective insulator characterized by: