JP2008116389A - Nondestructive corrosion diagnostic system for leakage oil of electrical apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diagnostic system that visually, nondestructively, and portably displays an abnormal place in which targeted leakage oil or corrosion is detected in oil filled apparatuses, such as transformers and breakers, and others, by remotely measuring with a simple image inputting device. <P>SOLUTION: The nondestructive corrosion diagnostic system for leakage oil of electrical apparatuses comprises five kinds of filters the center wavelengths of which are different from each other; the image inputting device 5 that outputs light in the range of wavelength from 390 nm to 2,000 nm that are captured through the filters, as two-dimensional image information; a light amount measuring section 6 that calculates a two-dimensional absorbance distribution from the two-dimensional image information; a storage section 8 that stores the master curve of an object to be measured; a calculation section 7 that calculates differences in two-dimensional absorbance or ratios of two-dimensional absorbance from the master curve and the two-dimensional absorbance distribution; a display section that displays an image from the calculated differences in two-dimensional absorbance or ratios of two-dimensional absorbance; and a light source of a discharge tube type that has an emission peak at the wavelength of 370 nm±10 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to maintenance management of power stations and substations, and is intended for the detection of oil leakage and corrosion of oil-filled equipment such as transformers and circuit breakers that have many on-site needs. More particularly, the present invention relates to a nondestructive oil leakage corrosion diagnostic apparatus for electric equipment that is portable and capable of making a diagnosis in a short time.

  As a technique for detecting oil leakage in electrical equipment, as described in Patent Document 3, a method of detecting by a transmission loss change when oil adheres to the surface of an optical fiber is described. There are known methods for detecting from absorption of base oil components using light having a wavelength of 1.66 to 1.79 μm, and detection methods using fluorescence when irradiated with ultraviolet light as described in Patent Document 2. Yes. Further, as a technique for detecting corrosion and coating film deterioration, a method using thermography using an infrared camera as described in Patent Document 5 and Patent Document 4 has been proposed.

JP 09-26375 A Japanese Patent Laid-Open No. 10-311771 JP 2002-107270 A JP 2003-226826 A JP 2004-37276 A

  However, the oil leakage detection method described in Patent Document 3 is a point diagnosis at a site where an optical fiber is installed, and the oil leakage status of the entire electrical equipment cannot be grasped. Further, the oil leakage detection method described in Patent Document 1 has a problem that a leakage oil flow path is necessary. The fluorescence method of Patent Document 2 also has a problem that it is difficult to detect under sunlight in the outdoors and to determine oil on a surface with an uneven surface. Furthermore, the techniques of Patent Document 5 and Patent Document 4 as techniques for detecting corrosion and coating film deterioration cannot be detected without a temperature field during operation.

  The present invention has been made in view of the above circumstances, and is intended for oil leakage / corrosion detection of oil-filled devices such as transformers and circuit breakers by remote measurement using an image input device in a simple and short time. An object of the present invention is to provide a diagnostic device that visually displays a non-contact abnormal part.

  In order to achieve the above object, the present invention achieves the above-described object, and includes five types of filters having different center wavelengths, an image input device that outputs light having a wavelength of 390 nm to 2000 nm taken through the filters as two-dimensional image information, and the two-dimensional A light quantity measuring unit that calculates a two-dimensional absorbance distribution based on the image information of the image, a storage unit that stores a master curve of the object to be measured, and a two-dimensional absorbance based on the master curve and the two-dimensional absorbance distribution A calculation unit that calculates a difference or two-dimensional absorbance ratio, a display unit that performs display based on the calculated absorbance difference or absorbance ratio, and a discharge tube type light source unit that has an emission peak at 370 nm ± 10 nm. The present invention provides a non-destructive oil leakage corrosion diagnostic device for electrical equipment.

  According to the present invention, a diagnosis that visually detects oil leakage and corrosion of oil-filled equipment such as a transformer and a circuit breaker by remote measurement using a simple image input device is performed in a contactless manner. Can do. Moreover, it is easy to make the non-destructive oil leakage diagnosis apparatus portable of the electrical equipment of the present invention, and it can be easily carried and diagnosed at the site where the diagnostic object is installed.

  The present inventors have studied in detail the relationship between insulating oil, coating film, rust and optical properties. As a result, it was clarified that the oil leakage can be improved by using a narrowband interference filter when the oil is irradiated with ultraviolet rays under sunlight. In addition, regarding the fluorescence of oil on the surface unevenness, the single-wavelength “fluorescence method” is easily affected by variations in fluorescence intensity, irregular reflection due to surface unevenness, and the like. It was clarified that it can be improved by utilizing the wavelength method. The contents of the study are described below.

As an ultraviolet (UV) light source, a wavelength of 370 nm from black light (a light source emitting a wavelength region of 360 nm to 380 nm (UV-A) having strong photochemical action and fluorescence action) was used. In addition, since the fluorescence appearing in the vicinity of 430 nm is difficult to compare in absolute intensity, the intensity (that is, the two-wavelength diagnosis of fluorescence) with respect to a reference wavelength region (here, a wavelength without a signal serving as a base line) centered on 670 nm. Compared. As a result, it was confirmed that when mineral oil for transformers (new oil, deteriorated oil), OF cable oil and silicone oil were irradiated with ultraviolet rays, fluorescence depending on the molecular structure of each oil was emitted. In contrast, no fluorescence was generated in water. The intensity of fluorescence
It was found that mineral oil (deteriorated oil)> mineral oil (new oil) >> OF cable oil> silicone oil. From this, it can be seen that the above four liquids and water can be discriminated even remotely, and the type of each leaked liquid can be discriminated from the intensity of fluorescence. Therefore, there is no need to change the light source depending on the type of oil, and a simple, small and light portable diagnostic device can be provided.

  The fluorescence from OF cable oil is weak compared to mineral oil. However, when the excitation light wavelength was 240 to 330 nm shorter than 370 nm, strong fluorescence was observed near 350 nm. The same can be said for silicone oil. However, the fluorescence of mineral oil was not detected with excitation light of 240 to 330 nm. Therefore, in addition to the diagnosis using the excitation light of 370 nm, when necessary, the diagnosis using the excitation light of 240 to 330 nm can be added to strongly detect the OF cable oil and the silicone oil.

  In the study under sunlight, as shown in FIG. 1, in the case of sunlight alone, the 370 nm radiation intensity itself is weaker than that of black light, and thus no clear fluorescence appears from mineral oil. Therefore, when black light is used as auxiliary light under sunlight, clear fluorescence is observed even under sunlight in a narrow wavelength region of about ± 5 nm centered at 405 nm, with respect to the reflection spectrum of only sunlight. It was. The emission peak in the region of 395 nm or less is due to direct reflection of black light, not due to the fluorescence of mineral oil. Further, in the region of 410 nm or more, the spectra were almost the same (no change was seen) when only sunlight or auxiliary light was used.

  Therefore, it was found that if a narrow band filter of 395 nm to 410 nm is used, fluorescence can be detected even under sunlight. Therefore, in the following examples, a band-pass filter having a half-value width of 10 nm with a center wavelength of 405 nm and a band-pass filter with a half-value width of 60 nm having a center wavelength of 670 nm were used.

  Moreover, according to said apparatus, it is possible to measure not only the above-mentioned oil leakage but a rust and a film thickness with the same apparatus by switching and using a combination of filters separately. In the following, changes in film thickness due to the paint withering and changes in optical properties due to the occurrence of rust will be described.

As shown in FIG. 2, as rust, spectra of four types of reagents (α-FeOOH, γ-FeOOH, Fe (OH) ₃ , α-Fe ₂ O ₃ ) were measured as model substances. When rust (reagent) was irradiated with near-infrared rays, it was confirmed that there was a wavelength region in which the reflection absorbance differs depending on the type of rust and a wavelength region in which there was no difference. The wavelength range where the absorption peak appears in common with no difference between the reagents was 800 nm to 1100 nm. The absorption peaks at 1450 nm and 1950 nm seen only in Fe (OH) ₃ hydroxide are due to harmonic absorption due to the hydroxyl group (OH group).

  Moreover, the wavelength range which does not absorb with any reagent is 1200 nm-1400 nm. Therefore, as the rust detection, a two-wavelength diagnosis with a wavelength range of 800 nm to 1100 nm showing absorption with respect to rust is performed using the wavelength region without absorption as a reference wavelength region.

  Next, the diagnosis of the film thickness will be described. When near infrared rays were irradiated to the coating film surface, it was confirmed that there was a wavelength region where the difference in reflection absorbance was different from that depending on the film thickness and a wavelength region where there was no difference. It can be said that the wavelength range where there is no difference depending on the film thickness is 1200 nm to 1400 nm centered on 1300 nm. On the other hand, the wavelength range where the difference occurs depending on the film thickness is a wavelength range of 1850 nm or more. Therefore, as a film thickness detection, a two-wavelength diagnosis is performed with a reference wavelength region of 1200 nm to 1400 nm and a region of 1850 nm or more that varies depending on the film thickness. In addition, the region where the absorption spectrum largely changes depending on the deterioration of the resin and the type of the pigment is a visible light region of 750 nm or less.

  Summarizing the above, it has been clarified that oil leakage and corrosion (rust, withering of paint film) of electrical equipment can be determined with high sensitivity by combining fluorescence two-wavelength diagnosis using an ultraviolet light source and near-infrared two-wavelength diagnosis. It was found that oil leakage and corrosion of electrical equipment can be determined from a non-destructive remote location by photographing the change in the image with a CCD camera or the like and measuring the absorbance from the image information.

  For example, the following may be considered as embodiments of the present invention. However, it is natural that the present invention is not limited to the following.

  In the non-destructive oil leakage diagnostic apparatus for electrical equipment, it is preferable that the center wavelengths of the five types of filters are 405 nm, 670 nm, 845 nm, 1300 nm, and 1850 nm, respectively. In addition, the non-destructive oil leakage corrosion diagnostic apparatus for electrical equipment is provided with a mechanism for driving the five types of filters on the optical axis of the image input device, for example, five filters on a disk connected to a rotation mechanism, It is desirable to provide a mechanism for setting each filter at a predetermined position by rotating it. With such a configuration, the filter mechanism can be reduced in size and made portable.

  In the non-destructive oil leakage corrosion diagnostic apparatus for electrical equipment, the two-dimensional absorbance difference or the two-dimensional absorbance ratio is determined by a near-ultraviolet two-wavelength method using a combination of a filter having a central wavelength of 405 nm and a filter having a central wavelength of 670 nm, and a central wavelength of 845 nm. And a filter having a center wavelength of 1300 nm and a combination of a filter having a center wavelength of 1300 nm and a filter having a center wavelength of 1850 nm are preferably obtained by the near infrared two-wavelength method.

  Further, it is desirable that the light source unit has a filter that cuts light having a wavelength of 380 nm or more (cut filter that cuts light in a wide range of about 380 nm to at least 2000 nm). A band-pass filter for obtaining excitation light in a wavelength range with a narrow energy range in accordance with the center wavelength cannot exclude excitation light outside the peripheral region of the center wavelength. Therefore, it is possible to reduce components other than the cutoff band by using a filter that widely excludes the excitation light on the long wavelength side, reliably reducing noise even under sunlight, and measuring the target fluorescence intensity. it can. The display on the display unit is a display for evaluating the progress of oil leakage corrosion, and it is desirable to change the display color according to the progress of the oil leakage corrosion. The two-dimensional image information may be in an uncompressed file format.

  The non-destructive oil leakage diagnostic apparatus for electrical equipment according to the present invention comprises five types of filters having different center wavelengths, an imaging device capable of capturing an image of an object through the filters, an input unit and a display unit. By configuring the imaging apparatus and the portable electronic computer that controls the mechanism for driving the filter and the light source having the emission peak at 370 nm ± 10 nm, the apparatus can be easily made portable. A portable CCD camera or the like can be used as the imaging device, a personal computer can be used as the portable electronic computer, and the light source and the filter can also be portable.

  The center wavelengths of the five types of filters are as described above, and the two-dimensional absorbance difference or the two-dimensional absorbance ratio is obtained by the two-wavelength light method as described above. Furthermore, it is preferable that a mechanism for driving the five types of filters on the optical axis of the image input apparatus is provided.

  The center wavelengths of the filters are 405 nm, 670 nm, 845 nm, 1300 nm, and 1850 nm, and it is better to have a filter that cuts visible light of 380 nm or more in the light source unit, to avoid the effects of uneven stray light on the surface and the influence of sunlight. It is suitable for.

  The display on the display unit is a display for evaluating the progress of oil leakage corrosion, and the display color can be changed according to the progress of the oil leakage corrosion. This can be done on the camera or of course on the computer that sent the data. Furthermore, the image input format is preferably an uncompressed file format (RAW, TIFF, etc.) in terms of measurement accuracy, but of course, a general-purpose JPEG format is also possible.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of examples.

(Example 1)
Example 1 shows an example in which oil leakage, rust, and film thickness are measured by switching and using a combination of filters.

  FIG. 3 is a block diagram showing a non-destructive diagnostic apparatus for an insulating material according to the present embodiment, and FIG. 5 shows a flowchart of calculation for determining oil leakage and corrosion (rust, paint wiping).

  The nondestructive diagnostic apparatus in FIG. 3 includes at least a lens 2 that captures image information of an object to be measured, a first filter 3, a second filter 4, an image input device 5, a light quantity measurement unit 6, and a calculation unit. 7 and a master curve storage unit 8. Although only two filters are shown in FIG. 3, five filters may be provided on one disk as described above.

  In the present embodiment, the first filter 3 serving as the spectroscopic means is a bandpass filter having a center wavelength of 405 nm, a half width of 10 nm, and a transmittance of 60%. The second filter 4 is a bandpass filter having a wavelength of 670 nm, a half width of 60 nm, and a transmittance of 80%.

A method for measuring the absorbance (A ₄₀₅ , A ₆₇₀ ) of the DUT 1 at each wavelength is shown below. Here, two-dimensional (image) information refers to information grasped as a spread of a plane, and specifically refers to information having a predetermined value (luminance value, absorbance, etc.) corresponding to vertical and horizontal coordinate positions.

First, an image of the object to be measured 1 from the first filter 3 is captured by the image input device 5 through the lens 1, and is output to the light quantity measuring unit 6 as light and shade two-dimensional image information. The light quantity measurement unit 6 converts the input two-dimensional grayscale image information into a luminance value for each pixel, which is the minimum unit for deterioration diagnosis, and outputs the result to the calculation unit 7. The calculation unit 7 calculates the absorbance of each pixel based on the reference luminance value (I ₀ ) obtained in advance, and stores it as a two-dimensional absorbance distribution at a wavelength of 405 nm.

Here, the reference luminance value (I ₀ ) is a value that is measured for each wavelength using copy paper (white paper) or the like before the measurement is started and is preset in the calculation unit 7. Similarly, the two-dimensional image information of the DUT 1 from the second filter 4 is captured by the image input device 5 and input to the light quantity measuring unit 6, and a two-dimensional absorbance distribution at a wavelength of 670 nm is a calculation unit that is a calculation means. 7

  The calculation unit 7 calculates the absorbance difference between the two wavelengths in the calculation unit 7 and stores the distribution for each pixel, and the relationship (master curve) between the fluorescence intensity of the insulating oil and the absorbance difference is stored in advance. A master curve in which the threshold value of oil leakage is stored is called from the storage unit 8, and the master curve is compared with the measured absorbance difference of the measured object for each pixel to determine whether or not fluorescence is generated by the insulating oil. Determination is made and the result is displayed on the display unit 9.

  FIG. 7 shows an example in which the fluorescence of the insulating oil adhered to the stone is observed using a 430 nm filter (comparative example) and a narrow-band 405 nm filter. In the comparative example, the presence of the insulating oil is clear. In addition, there is a lot of noise on the left side of the sample. On the other hand, when a narrow band filter is used, the presence of insulating oil is clear and no noise is seen.

  Next, an example in which rust is detected by the same device will be described. Using test pieces (new, rusted, repainted on rust, 3 types coated with bengara on the ground) with a cross mark with oil-based ink on the coated steel sheet, 845nm and 1300nm The two-dimensional absorbance difference of the filter was measured. As a result, the oil-based ink does not appear as an image, and in the case of a new product, the image showing rust is not displayed, the shape of the repainted rust is clearly displayed, and the iron oxide of Bengala is applied to the entire surface of the undercoat of Bengala It was clearly displayed.

  Next, an example in which the film thickness is detected using the same apparatus will be described. In FIG. 6, 1 is the top coat once (average), 2 is the top coat twice (average), and 3 is the top coat three times (average) film thickness and the relationship between the reflection absorbance. Filters with 1300 nm and 1850 nm were used. From this data, it can be seen that the thinner the film thickness, the larger the difference in reflection absorbance.

The outline of the diagnostic algorithm used for the above-mentioned diagnosis is as follows.
(1) Display color settings (6 colors: red, pink, yellow-green, green, blue, white)
However, the display color threshold can be arbitrarily set.
(2) Captured image input (3 types; normal image (for object confirmation), wavelength λ1 image, wavelength λ2 image)
Here, the wavelengths λ1 and λ2 for each detection technique are as shown in Table 1.

(3) Diagnostic range setting (maximum size: 1024 x 768 pixels)
(4) Image processing i. Luminance conversion: {wavelength λ1 luminance (Iλ1), wavelength λ2 luminance (Iλ2)}
ii. Calculation of difference in absorbance (ΔAr) [ΔAr = − {log (Iλ1) −log (Iλ2)}]
iii. 2D image display (color display)
FIG. 4 is a block diagram of a portable nondestructive oil leakage corrosion diagnosis apparatus according to another embodiment. The imaging apparatus (digital camera or the like) 10, the input device (personal computer or the like) 13 having a display unit 15, and the input device power supply ( 14) a filter mechanism 11 having five types of filters, a light source 16, and a filter 17 that cuts visible light. The input device 13 includes a drive mechanism 12 for the filter mechanism 11 and a camera 10. The input device 13, the power supply 14, the imaging device 10, and the filter mechanism 11 can be carried by an operator together with the light source 16 and the filter 17 as one set.

The reflection spectrum spectrum figure at the time of black light irradiation under sunlight. Reflection spectrum diagram of a test piece (without rust) with a different coating thickness. 1 is a block diagram showing an example of a nondestructive oil leakage and corrosion diagnosis apparatus according to an embodiment of the present invention. The block diagram which shows the portable nondestructive oil leakage corrosion diagnostic apparatus by the other Example of this invention. The flowchart of the calculation for oil leak and corrosion determination. The master curve figure which shows the relationship between a film thickness and a reflective absorbance difference. The diagnostic imaging photograph by the detection example of the insulating oil adhering to unevenness stone.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Object to be measured, 2 ... Lens, 3 ... 1st filter, 4 ... 2nd filter, 5 ... Image input device, 6 ... Light quantity measurement part, 7 ... Calculation part, 8 ... Master curve memory | storage part, 9 ... Display part .

Claims (8)

5 types of filters with different center wavelengths,
An image input device that outputs light from a wavelength of 390 nm to a wavelength of 2000 nm captured through the filter as two-dimensional image information;
A light quantity measuring unit that calculates a two-dimensional absorbance distribution based on the two-dimensional image information;
A storage unit for storing the master curve of the object to be measured;
A calculation unit that calculates a two-dimensional absorbance difference or a two-dimensional absorbance ratio based on the master curve and the two-dimensional absorbance distribution;
A display unit for displaying a diagnosis result based on the calculated absorbance difference or the absorbance ratio;
A discharge tube type light source having an emission peak at 370 nm ± 10 nm;
A non-destructive oil leakage corrosion diagnostic apparatus for electrical equipment, characterized by comprising:   The non-destructive electrical device according to claim 1, further comprising: an imaging device that captures an image of the object to be measured; a drive mechanism that drives the imaging device; and a portable computer that controls the drive mechanism. Oil leakage corrosion diagnosis device.   The nondestructive oil leakage corrosion diagnostic apparatus for electrical equipment according to claim 1 or 2, wherein the center wavelengths of the five types of filters are 405 nm, 670 nm, 845 nm, 1300 nm, and 1850 nm, respectively.   The non-destructive oil leakage corrosion diagnostic apparatus for an electric device according to any one of claims 1 to 3, further comprising a mechanism for driving the five types of filters on an optical axis of the image input device.   The two-dimensional absorbance difference or the two-dimensional absorbance ratio includes a filter with a central wavelength of 405 nm and a filter with a central wavelength of 670 nm, a filter with a central wavelength of 845 nm and a filter with a central wavelength of 1300 nm, and a filter with a central wavelength of 1300 nm and a filter with a central wavelength of 1850 nm. The nondestructive oil leakage corrosion diagnosis apparatus for electrical equipment according to any one of claims 1 to 4, characterized in that it is obtained by a combination of   The nondestructive oil leakage corrosion diagnostic apparatus for an electric device according to any one of claims 1 to 5, wherein the light source unit includes a filter that cuts light having a wavelength of 380 nm or more.   The display of the said display part is a display of evaluation of the progress of oil leakage corrosion, A display color is changed according to the progress of the said oil leakage corrosion, The electric device in any one of Claims 1-6 characterized by the above-mentioned. Non-destructive oil leakage corrosion diagnostic device.   The non-destructive oil leakage corrosion diagnostic apparatus for electrical equipment according to claim 1, wherein the two-dimensional image information is in an uncompressed file format.

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