JP4412138B2 - Luminescence detection device - Google Patents

Description

  The present invention relates to a light emission detection device for detecting a position where ultraviolet rays are generated by light emission, and more particularly to a light emission detection device effective for detecting the occurrence of corona discharge in an electrical facility such as a power transmission tower.

In electrical equipment, a minute corona discharge may occur with the deterioration of electrical insulation. That is, by detecting corona discharge, electrical insulation deterioration can be detected at an early stage.
As an apparatus for detecting this corona discharge, for example, there is a detection apparatus described in Patent Document 1. In this detection apparatus, ultrasonic sound when corona discharge occurs is detected, and the presence and position of corona discharge is detected by specifying the direction of sound generation based on the detection.
JP-A-9-233679

However, in the detection method using sound at the time of discharging, it is necessary to move the acoustic detection unit so as to scan the subject to be inspected. Therefore, the larger the subject, the longer the inspection takes.
Further, since the magnetostrictive vibration sound or the like approximates the discharge sound, it may be erroneously detected that the corona discharge is detected even though there is no corona discharge.
The present invention has been made paying attention to the above points, and it is an object of the present invention to provide a light emission detecting device capable of detecting abnormal light emission by corona discharge or the like with a more accurate and simple configuration.

  In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention includes a lens barrel, a concave mirror that reflects light incident on the lens barrel, and a UV-C region disposed facing the concave mirror. An optical filter that allows only ultraviolet light to pass through, a visualization conversion unit that visualizes an ultraviolet image after passing through the optical filter, a first image acquisition unit that acquires an ultraviolet image visualized by the visualization conversion unit, and light reflected by the optical filter And a second image acquisition means for acquiring a visible image according to the above.

Next, the invention described in claim 2 is characterized in that, with respect to the configuration described in claim 1 , the presence / absence and position of corona discharge is specified based on the images acquired by the two image acquisition means. is there.
Next, the invention described in claim 3, emission lines in the luminescence detection apparatus according to claim 1 or 2, wherein the optical filter is present in the range of wavelengths 240Nm～280nm 1 or 2 or more Ne (neon) It is a narrow-band pass filter that passes through.

  According to the present invention, the number of used expensive UV lenses sensitive to ultraviolet rays (lenses that allow only UV-C to pass) can be suppressed by condensing the light with a reflecting mirror. Moreover, a visible image and an ultraviolet image can be acquired by incident light from the same optical axis. That is, it is possible to suppress the occurrence of a shift in the visible image and the ultraviolet image due to the distance from the subject.

Embodiments of the present invention will be described below with reference to the drawings.
First, the discharge phenomenon and ultraviolet rays will be described.
It is known that the discharge phenomenon involves emission of ultraviolet rays in addition to electromagnetic waves and ultrasonic waves. Discharge is caused by gas atoms in an excited state under the influence of an electric field emitting free electrons and being ionized. At this time, light is emitted in the process in which the ionized atom receives free electrons and returns from the excited state to the ground state.
Here, the wavelength of light emitted when the electron trajectory transitions from n = i to n = j is given by the following equation (1).

Where λ: wavelength of emitted light, m: kinetic mass of electron, e: charge of electron (1.602 × 10 ⁻¹⁹ C), ε ₀ : dielectric constant of vacuum (8.854 × 10 ⁻¹² F) / M), h: Planck's constant (6.624 × 10 ⁻³⁴ J · sec), c: speed of light (3 × 10 ⁸ m / sec)
Here, the inventor of the present application pays attention to the fact that the ionization voltage of each atom is given by the following formula (2). I thought that it can be obtained in (3).

  FIG. 1 shows an emission spectrum of a typical gas obtained by the equation (3). From the figure, it can be seen that the wavelength of light generated by the discharge is discretely distributed in the ultraviolet region of 400 nm or less. On the other hand, ultraviolet rays are classified into UV-A from 400 nm to 315 nm, UV-B from 315 nm to 280 nm, and UV-C from 280 nm to 100 nm depending on the wavelength.

  By the way, ultraviolet rays are short-wave electromagnetic waves having a wavelength of 400 nm or less, which are emitted from artificial lighting such as the sun and high-intensity lamps. In particular, in the case of solar radiation reaching the ground surface, the emission distribution shown in FIG. Thus, the shorter the wavelength, the smaller the occupation ratio in solar radiation. In particular, the electromagnetic wave in the UV-C region is absorbed by the ozone layer in the atmosphere, and therefore hardly reaches the ground surface. On the other hand, the light emission distribution by corona discharge is as shown in FIG. 2 and radiates over the entire ultraviolet region. Therefore, by detecting ultraviolet rays in the UV-C region that do not exist in the solar radiation that reaches the ground surface, it is not affected by solar radiation, and even weak discharge light is not affected by sunlight, such as corona discharge. Ultraviolet rays accompanying light emission from the subject itself due to the occurrence can be detected.

Next, a first embodiment of the present invention will be described with reference to the drawings.
In all of the following embodiments, a discharge detection device that detects corona discharge will be described as an example of a light emission detection device that detects ultraviolet light emission. Of course, the detection is not limited to the detection of corona discharge as long as it detects a part that generates ultraviolet light emission due to some trouble.
First, the structure of the discharge detection device of this embodiment will be described. FIG. 3 is a schematic configuration diagram of the apparatus.

A concave mirror 2 is arranged coaxially in a cylindrical barrel 1. A UV filter 3 is disposed confrontingly and coaxially with the concave mirror 2. An ICCD camera 4 is coaxially disposed behind the UV filter 3. The ICCD camera 4 is composed of an image intensifier 4A and a CCD camera main body 4B constituting the first image acquisition means, and image data picked up by the CCD camera main body 4B is output to the image processing unit 5. . The UV filter 3 and the ICCD camera 4 are supported on the lens barrel 1 by a spider (not shown).
The image intensifier 4A is a device that constitutes a visualization conversion unit, and detects and multiplies a weak ultraviolet image to convert it into a contrasted image, that is, a visualized image. In addition, since a normal CCD camera does not have sensitivity to ultraviolet rays, the discharge phenomenon cannot be imaged.

The image intensifier 4A is an MCP that doubles photoelectrons by processing an infinite number of fine holes (channels) of φ12μm on a light-receiving surface that converts received light into electrons and a thin glass plate with a diameter of 25mm and a thickness of 0.48mm. (Multi-channel plate) and a fiber plate that converts the doubled electrons into light again and transmits them to the subsequent stage. In this embodiment, Ce-Te having sensitivity to ultraviolet rays is selected as the material for the light receiving surface of the image intensifier 4A. The Ce-Te light-receiving surface is suppressed in sensitivity to light having a wavelength of 320 nm or more and has maximum sensitivity in the vicinity of 250 nm. And MCP made the electron multiplication rate 10 ⁶ times by considering the weak discharge light and making it two steps. Here, since the image intensifier 4A has a high amplification factor, it forms an image even with a small amount of light and hinders discrimination of the discharge light to be originally observed. Therefore, a UV filter 3 that allows only UV-C light to pass through is installed in front of the image intensifier 4A to block unnecessary light.

  By the way, normally, the filter includes a band pass filter that passes a specific wavelength band and a narrow band pass filter that passes only a specific wavelength (see, for example, FIG. 1). A filter that passes only UV-C ultraviolet rays in the range of 280 nm is preferred. In particular, in the filter selection in this embodiment, as a result of laboratory tests using five types of narrow band pass filters, as shown in FIG. 4, the narrow band pass filter that passes 249.7 nm has the best S / N ratio. It was suitable for visualization of discharge. In the example of the figure, discharge is generated at the bottom center of the screen, but it can be seen that it is difficult to discriminate between the discharge light and the background sunlight with a filter other than 260BP and 249.7NB7.

Here, in the image that has passed through the 249.7NB7 filter shown in FIG. 4, Ne (neon) emission lines are mainly observed as can be seen with reference to FIG. Neon nitrogen (volume ratio 78.088% in air), oxygen (up 20.949%), argon volume ratio in the atmosphere subsequent to (the same 0.93%) larger gas (the 1.8 × 10 ^{- 3%),} most volume ratio is large in the gas with an emission line in the UV-C region. Therefore, it is preferable to discriminate the Ne (neon) emission line because the amount of emitted light is large. Furthermore, in the present embodiment, a narrow band pass filter that passes one or more emission lines of 249.7 nm, that is, Ne (neon) among UV-C ultraviolet rays existing in a wavelength range of 240 to 280 nm is provided. The UV filter 3 is used. Therefore, by adopting such a narrow band pass filter, the discrimination between the discharge light and the background sunlight can be made more reliable.

  A visible light CCD camera 6 that captures a visible image of light reflected from the surface of the UV filter 3 is disposed at a position facing the front surface (incident surface) of the UV filter 3. This visible light CCD camera 6 constitutes a second image acquisition means. The visible light CCD camera 6 outputs the captured visualized image data to the image processing unit 5. Here, the visible light CCD camera 6 has a position and a size that do not block the optical path from the concave mirror 2 to the optical filter. The visible light CCD camera 6 is supported by the case of the UV filter 3 or the lens barrel 1. Here, the visible image acquired by the visible light CCD camera is an image like the image of FIG. 5A, and the ultraviolet image acquired by the ICCD camera is an image like the image of FIG. 5B. Become. Since the ultraviolet image is whitish only in the ultraviolet part, FIG. 5B is actually an image in which only the light emitting part A by corona discharge is whitish and the background is black.

  The image processing unit 5 receives a UV image from the ICCD camera 4 and a visualized image from the visible light CCD camera 6 (a visible image of the subject 10) based on the same incident light, which are input in synchronization. Are combined and output to the display unit 7. Note that the visual image from the visible light CCD camera 6 and the ultraviolet image from the ICCD camera 4 are synthesized so that the visibility of the discharge image can be improved by arbitrarily adjusting the mixing level with a video mixer. .

Next, the operation, action, and effect of the above-configured discharge detection apparatus will be described.
This apparatus is used by directing the opening of the lens barrel 1 to the subject 10 and operating the two cameras 4 and 6 in this state.
When light from the subject 10 enters the lens barrel 1, the incident light is reflected by the concave mirror 2, which is the main reflecting mirror, and is concentrated on the incident surface of the UV filter 3 that is disposed facing. Of the light incident on the incident surface of the UV filter 3, only the ultraviolet light in the UV-C region passes through the UV filter 3 and is received by the ICCD camera 4. The ultraviolet image captured by the ICCD camera 4 5 is supplied. Here, since the ultraviolet rays in the UV-C region do not exist in the sunlight that reaches the ground, the ultraviolet rays that have passed through the UV filter 3 are only ultraviolet rays due to light emission of the subject 10. That is, the image output from the ICCD camera 4 is an image that displays only ultraviolet rays corresponding to corona discharge.

Then, the two images inputted in synchronization by the image processing unit 5 are combined and displayed on the display unit 7. Note that it may be recorded in a recording unit instead of the display unit 7 and reproduced and confirmed later.
The image displayed on the display unit 7 is a composite of a visible image of the subject 10 and a black image if the subject 10 has no corona discharge. It is an image. On the other hand, when a minute corona discharge is generated in a part of the subject 10, the ultraviolet image is an image in which only the portion where the corona discharge is generated with respect to the black background is whitish. In the displayed image after synthesis, only the corona discharge portion is a combined image that is displayed whitish (brighter), so that it is possible to detect the presence and position of corona discharge.

In this embodiment, since the magnification of the image is increased by the concave mirror 2, the number of expensive UV lenses (for example, a quartz lens for UV) can be reduced, and the apparatus becomes cheaper by that amount. Note that a UV lens is appropriately used depending on the degree of visualization of the ultraviolet image. Ordinary lenses will absorb ultraviolet rays.
Further, since the ultraviolet image and the visible image are acquired from the same incident light having the same optical axis, there is no shift due to the distance between the two images and the subject 10, so that the synthesis is performed. Cheap. In addition, when the magnification of the ultraviolet image input to the image processing unit 5 and the visible image are different, image processing is performed so that the magnification is equal. However, since the images are from the same viewpoint, the magnification is simply changed. do it.

  Here, in the above embodiment, since the incident surface of the UV filter 3 has a flat finish, the focal point of the light reflected by the UV filter 3 is located in front of the concave mirror 2. For this reason, the visible light CCD camera 6 is disposed in front of the concave mirror 2, but the present invention is not limited to this. A visible light CCD camera 6 is disposed at the same position as the concave mirror 2 or at a position behind the concave mirror 2, and the reflected light from the UV filter 3 is optically CCDed via an optical element (such as a convex lens, a concave lens, a reflecting mirror, and a prism). You may set so that it may guide to the light-receiving surface.

In addition, color conversion processing may be performed only on an ultraviolet image by corona discharge by image processing, that is, the white portion may be converted to red or the like to further emphasize the corona discharge portion.
In the above embodiment, the ultraviolet image and the visible image are combined by the image processing unit 5 and displayed on the display unit 2, but the present invention is not limited to this. For example, the ultraviolet image and the visible image are made the same size in the image processing unit 5 (this processing is not necessary when the magnification is the same at the time of input to the image processing unit 5). You may make it display on the display part 7 side by side. Although the accuracy of the position of the corona discharge is slightly inferior, the presence / absence of the corona discharge and the approximate position of the corona discharge can be specified.

Moreover, in the said embodiment, although the concave mirror 2 and the UV filter 3 are arrange | positioned coaxially with respect to the lens barrel 1 on the axis | shaft of the said lens barrel 1, it is not limited to this. For example, as shown in FIG. 6, the axis of the concave mirror 2 is inclined with respect to the axis of the lens barrel 1, and the reflected light from the concave mirror 2 is condensed outside the optical path toward the concave mirror 2, and the UV filter 3 is disposed in the vicinity of the condensing part. May be arranged.
In the example of the above embodiment, the UV filter 3 is a narrow band pass filter that passes a bright line of 249.7 nm Ne (neon), but is not limited to this, and the narrow band pass filter has a wavelength of You may observe by the narrow-band pass filter which passes the bright line of 1 or 2 or more Ne (neon) of another wavelength among UV-C ultraviolet rays which exists in the range of 240-280 nm.

Next, a second embodiment will be described with reference to the drawings. In addition, about the components similar to the said embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.
As shown in FIG. 7, the basic configuration of the present embodiment is the same as that of the first embodiment, except that the incident side surface 3a of the UV filter 3 has a convex finish.
In this example, the surface of the UV filter 3 is focused on the convex surface so that the focal point of the light reflected is set at the rear position of the concave mirror 2, and the visible light CCD camera 6 is disposed behind the concave mirror 2.
In FIG. 7, reference numeral 8 denotes a UV lens, which is an example in which the magnification of the ultraviolet image is further increased. Reference numeral 9 denotes an ordinary lens.
Other configurations, operations and effects are the same as those in the above embodiment.

Next, a third embodiment will be described with reference to the drawings. The same parts as those in the above embodiments will be described with the same reference numerals.
In the present embodiment, as shown in FIG. 8, a convex mirror 11 as a sub-reflecting mirror is disposed at the position of the UV filter 3, and the light reflected by the convex mirror 11 is condensed behind the concave mirror 2. Then, the light reflected by the convex mirror 11 is split into two optical paths by the spectroscope 12, one split light is sent to the UV filter 3, and the other is sent to the visible light CCD camera 6. The ICCD camera 4 is disposed behind the UV filter 3 via the UV lens 8 as in the second embodiment.

Other configurations are the same as those in the above embodiments.
In the present embodiment, the light incident on the concave mirror 2 is reflected and condensed on the convex mirror 11 (sub-reflecting mirror), and the light reflected on the convex mirror 11 is sent to the spectroscope 12. Subsequently, the light is split by the spectroscope 12 and light is sent to the respective cameras 4 and 6.
Other configurations, operations and effects are the same.

Next, examples of the present invention will be described.
The light emission detection device of the first embodiment was brought into the open inspection of the generator, and partial discharge photography was performed.
The generator in this example is a generator that has been operating for about 15 years, and since an increase in partial discharge has been observed in recent years, open inspection was performed with the light emission detection device of the first embodiment. Prior to the inspection, a partial discharge test was conducted while monitoring with a light emission detector, and an attempt was made to identify the discharge site. As a result, the partial discharge generated at the coil end could be detected. Partial discharge was spot-generated near the slot exit at the coil end.

After completion of the partial discharge test, the occurrence site was inspected, and a gap of about 0.2 mm was generated between the coil and the slot. Therefore, repair was performed by inserting a conductive material into the gap generated in the slot and solidifying with resin, and in the partial discharge test conducted after the repair, no visible image of discharge was observed.
As described above, the light emission detection device of the present invention can be applied to a partial discharge test of a generator / motor, for example, to easily identify the discharge site and easily check whether the repair is successful. It was confirmed that can be done.

It is explanatory drawing which shows the emission spectrum of typical gas. It is a figure explaining light emission distribution. 1 is a schematic configuration diagram of a discharge detection device according to a first embodiment based on the present invention. It is a figure explaining the result of the laboratory test for filter selection. It is a figure explaining the image of two types of ultraviolet images. It is a structure schematic diagram of another arrangement | positioning of the discharge detection apparatus which concerns on 1st Embodiment based on this invention. It is a structure schematic diagram of the discharge detection apparatus which concerns on 2nd Embodiment based on this invention. It is a structure schematic diagram of the discharge detection apparatus which concerns on 3rd Embodiment based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens tube 2 Concave mirror 3 UV filter 4 ICCD camera 4A Image indentifier 4B Camera main body 5 Image processing part 6 Visible light CCD camera 7 Display part 8 UV lens 9 Lens 10 Subject 11 Convex mirror (sub-reflector)
12 Spectrometer

Claims (3)

  A lens barrel, a concave mirror that reflects the light incident on the lens barrel, an optical filter that is disposed facing the concave mirror and transmits only ultraviolet rays in the UV-C region, and a visualization conversion that visualizes an ultraviolet image after passing through the optical filter Means, a first image acquisition means for acquiring an ultraviolet image visualized by the visualization conversion means, and a second image acquisition means for acquiring a visible image by light reflected by the optical filter. Luminescence detection device. 2. The light emission detection device according to claim 1, wherein the presence / absence and position of corona discharge are specified based on images acquired by the two image acquisition means . 3. The light emission detection device according to claim 1 , wherein the optical filter is a narrow band pass filter that allows passage of one or more Ne (neon) emission lines existing in a wavelength range of 240 nm to 280 nm. .