JP2006226910A - Abnormality detection method and detector for solid insulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection method and detector for a solid insulator suitable for practical use. <P>SOLUTION: This abnormality detector for detecting abnormality in an inside of the solid insulator 1 opaque to a visible light is provided with an electromagnetic wave source 3 for emitting an electromagnetic wave of a wavelength transmitted through the solid insulator 1 out of a terahertz wave, a submillimeter wave and a millimeter wave, a transmittance measuring instrument 4 for measuring a transmittance of a transmission wave 2 from the solid insulator 1, and a detecting means 5 for detecting an abnormality portion, based on a change of the transmittance in the abnormality portion, a change of the transmittance in a boundary portion between the abnormality portion and a normal portion, and a change on a transmission wave polarization face due to a change of a dielectric tensor in the abnormality portion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an abnormality detection method and an abnormality detection apparatus for a solid insulator. More specifically, the present invention relates to an abnormality detection method and an abnormality detection device for detecting an internal abnormality of a solid insulator in a non-destructive and non-contact manner. In the present application, the terahertz wave (THz wave) refers to an electromagnetic wave having a frequency centered around 1 THz to 30 THz and including a slight error above and below the submillimeter wave, and the submillimeter wave has a wavelength of 0.1 mm to 1 mm (frequency). Is an electromagnetic wave in a range that includes some errors above and below it, and the millimeter wave is centered on a wavelength of 1 mm to 10 mm (frequency is 30 GHz to 300 GHz) and has some errors above and below it. This refers to the electromagnetic waves within the range.

  What is proposed as a terahertz wave utilization technique is an internal measurement technique that utilizes the difference in transmission and absorption rates of terahertz waves. For example, since a terahertz wave cannot pass through a metal, an application has been proposed in which a wiring image is obtained by obtaining a perspective image of a molded part for an IC package molded with a plastic material (Non-patent Document 1).

  As an invention related to this, there is a differential imaging apparatus using a terahertz wave disclosed in Japanese Patent Application Laid-Open No. 2004-108905. This differential imaging apparatus is shown in FIG. The terahertz wave generator 101 generates two different wavelengths of terahertz waves 102 in a frequency range of about 0.5 to 3 THz, irradiates the target object 103 with the two wavelengths of terahertz waves 102, and measures the respective transmittances. The target is measured by the device 104, and the presence or absence of a target having wavelength dependency in the absorption of the terahertz wave 102 is detected by the target detection device 105 from the difference in transmittance. Further, the two-dimensional scanning device 106 two-dimensionally scans the surface of the object 103 with two different wavelengths of terahertz waves 102 so that the positions where the two-wavelength transmittances are different are displayed two-dimensionally. ing.

  In recent years, power facilities such as substations tend to expand the use of solid insulators. In order to make effective use of solid insulators, it is necessary to develop a technology that reliably detects non-destructive abnormalities such as the generation of internal voids and concentration of electrical and mechanical strains.

JP 2004-108905 A Hiromichi Kawase, Hiromasa Ito, “Possibility of imaging application of terahertz light source”, Journal of Japanese Society of Radiological Technology, Vol. 58, No. 4, p441-447, April 2002

  However, some solid insulators are opaque to terahertz waves, and in this case, the above-described differential imaging apparatus cannot be used. For this reason, there is a great limitation on the types of solid insulators that can be used. Further, the above-described differential imaging apparatus cannot detect abnormalities such as electrical and mechanical strains. For these reasons, it is inferior in practicality for detecting an abnormality of a solid insulator. Furthermore, for practical use, it is necessary to ensure that the abnormality can be reliably detected even if the abnormality in the solid insulator is fine, such as bubbles or cracks, and the detection performance is further improved. It is desired.

  An object of the present invention is to provide an abnormality detection method and an abnormality detection device for a solid insulator that are suitable for practical use for detecting an abnormality of a solid insulator.

  As a result of earnest research to make the detection of abnormal parts such as bubbles present in the solid insulator more reliable, the present inventor has found that when there are bubbles in the solid insulator, the solid insulator part The present inventors have found that the transmittance of terahertz waves differs between the (normal portion) and the bubble portion (abnormal portion), and that the terahertz wave transmittance also changes at the boundary between the solid insulator portion and the bubble portion.

  That is, a typical polyethylene was used as a solid insulator, and an experiment was performed by simulating a case where there was a void inside. Since there is a slight transmittance difference between air and polyethylene, there is a possibility that bubbles in polyethylene can be detected using terahertz waves, and in order to check how much the difference in transmittance between air and polyethylene can be distinguished, Using a sample (FIG. 9) in which two holes were formed in a 5 mm-thick polyethylene plate, a two-dimensional scan (method of moving and scanning the sample) image was obtained using a 1.3 THz terahertz wave.

  The results are shown in FIGS. A difference in transmittance between the polyethylene portion and the hole (air) portion was observed to some extent, but a phenomenon in which the transmittance was drastically decreased at the boundary portion between the polyethylene portion and the air portion was observed. This is thought to be due to the refraction and scattering of terahertz waves at the interface between polyethylene and air. The refraction / scattering phenomenon at the interface is considered to occur not only at the interface between polyethylene and air but also at the interface between other substances. Such a phenomenon is considered to occur not only when a terahertz wave is used but also when a submillimeter wave or a millimeter wave that is the same electromagnetic wave as the terahertz wave is used. Therefore, in addition to the change in the transmittance of the abnormal part and the normal part, the abnormal part is detected based on the change in the transmittance of the boundary part between the two, which is a larger change than this change, making detection easier and more reliable. And the present invention has been achieved.

  The invention according to claim 1 is a solid insulator abnormality detection method for detecting an abnormality inside a solid insulator that is opaque to visible light, and transmits the solid insulator of terahertz waves, submillimeter waves, and millimeter waves. Select the wavelength, irradiate the solid insulator with the electromagnetic wave of the selected wavelength, measure the transmittance of the transmitted wave, change the transmittance of the abnormal part and the transmittance of the boundary part between the abnormal part and the normal part An abnormal part is detected based on the change.

  Therefore, the electromagnetic wave irradiated to the solid insulator passes through the solid insulator. If there is no abnormality inside the solid insulator, the transmittance is constant in all parts. On the other hand, when there is an abnormality such as an air gap inside the solid insulator, the transmittance of the transmitted wave changes at the abnormal part, and the transmittance of the transmitted wave also changes at the boundary part between the abnormal part and the normal part. . The change in transmittance at the boundary portion is larger than the change in transmittance at the abnormal portion. For this reason, an abnormal part is emphasized by the transmittance | permeability change of the surrounding boundary part. That is, it is possible to detect an abnormal part while enhancing it.

  According to a second aspect of the present invention, in the solid insulator abnormality detection method for detecting an abnormality inside the solid insulator that is opaque to visible light, the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves. Select the transmission wavelength, irradiate the solid insulator with the electromagnetic wave of the selected wavelength, measure the polarization fluctuation of the transmitted wave, and detect the abnormal part based on the change of the polarization plane due to the change of the dielectric constant tensor of the abnormal part It is to detect.

  Therefore, the electromagnetic wave irradiated to the solid insulator passes through the solid insulator. If there is no abnormality inside the solid insulator, the change amount of the dielectric constant tensor is zero in all parts. On the other hand, when there is an abnormality such as an electrical or mechanical strain inside the solid insulator, the dielectric constant tensor changes at the abnormal part. An abnormal portion is detected based on the change in the polarization plane of the transmitted wave due to the change in the dielectric constant tensor.

  Furthermore, the invention described in claim 3 is a solid insulator abnormality detection method for detecting an abnormality inside a solid insulator that is opaque to visible light, wherein a solid insulator of terahertz waves, submillimeter waves, and millimeter waves is used. Select the transmission wavelength, irradiate the solid insulator with the electromagnetic wave of the selected wavelength, measure the transmittance and polarization fluctuation of the transmitted wave, change the transmittance of the abnormal part, and the abnormal part and the normal part The abnormal part is detected based on the change of the polarization plane due to the change of the transmittance of the boundary part and the change of the dielectric constant tensor of the abnormal part.

  Therefore, the electromagnetic wave irradiated to the solid insulator passes through the solid insulator. If there is no abnormality inside the solid insulator, the transmittance is constant in all parts, and the change amount of the dielectric constant tensor is zero. On the other hand, when there is an abnormality such as an air gap inside the solid insulator, the transmittance of the transmitted wave changes at the abnormal part, and the transmittance of the transmitted wave also changes at the boundary part between the abnormal part and the normal part. . The change in transmittance at the boundary portion is larger than the change in transmittance at the abnormal portion. For this reason, the abnormal part is emphasized by the change in the transmittance of the surrounding boundary part, and the abnormal part is detected while being emphasized. Further, when there is an abnormality such as an electrical strain, a mechanical strain, or a strain due to temperature non-uniformity in the solid insulator, the dielectric constant tensor changes at the abnormal portion. An abnormal part is detected based on this change. That is, an abnormal portion can be detected based on a change in the transmitted wave polarization plane due to a change in transmittance and a change in dielectric constant tensor.

  According to a fourth aspect of the present invention, there is provided a solid insulator abnormality detecting device for detecting an abnormality inside a solid insulator that is opaque to visible light, wherein a solid insulator of terahertz waves, submillimeter waves, and millimeter waves is used. An electromagnetic wave source that irradiates a solid insulator with an electromagnetic wave having a transmitted wavelength, a transmittance measuring device that measures the transmittance of the transmitted wave of the solid insulator, a change in the transmittance of the abnormal part, and an abnormal part and a normal part Detection means for detecting an abnormal part based on a change in the transmittance of the boundary part is provided.

  Therefore, the electromagnetic wave irradiated from the electromagnetic wave source toward the solid insulator passes through the solid insulator. The transmittance measuring device measures the transmittance of the transmitted wave. If there is no abnormality inside the solid insulator, the transmittance is constant in all parts. On the other hand, when there is an abnormality such as an air gap inside the solid insulator, the transmittance of the transmitted wave changes at the abnormal part, and the transmittance of the transmitted wave also changes at the boundary part between the abnormal part and the normal part. . The change in transmittance at the boundary portion is larger than the change in transmittance at the abnormal portion. For this reason, an abnormal part is emphasized by the transmittance | permeability change of the surrounding boundary part. The detecting means detects the emphasized abnormal part.

  According to a fifth aspect of the present invention, there is provided an abnormality detection apparatus for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, wherein a solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves. Based on electromagnetic wave source that irradiates solid insulator with electromagnetic wave of transmitted wavelength, polarization measuring device that measures polarization fluctuation of transmitted wave of solid insulator, and change of polarization plane due to change of dielectric constant tensor of abnormal part And detecting means for detecting an abnormal part.

  Therefore, the electromagnetic wave irradiated from the electromagnetic wave source toward the solid insulator passes through the solid insulator. The polarization measuring device measures the polarization fluctuation of the transmitted wave. If there is no abnormality inside the solid insulator, the change amount of the dielectric constant tensor is zero in all parts. On the other hand, when there is an abnormality such as an electrical or mechanical strain inside the solid insulator, the dielectric constant tensor changes in the abnormal part, and the polarization plane of the transmitted wave changes in the abnormal part. The detecting means detects an abnormal part based on this change.

  Furthermore, the invention described in claim 6 is a solid insulator abnormality detecting device for detecting an abnormality inside a solid insulator that is opaque to visible light, wherein a solid insulator of terahertz wave, submillimeter wave and millimeter wave is used. An electromagnetic wave source that irradiates a solid insulator with an electromagnetic wave having a transmitted wavelength, a transmittance measuring device that measures the transmittance of the transmitted wave of the solid insulator, and a polarization measurement that measures the polarization fluctuation of the transmitted wave of the solid insulator Detection that detects anomalous parts based on changes in the transmittance of the device, abnormal part, changes in transmittance at the boundary between the abnormal part and normal part, and changes in polarization plane due to changes in the dielectric constant tensor of the abnormal part Means are provided.

  Therefore, the electromagnetic wave irradiated from the electromagnetic wave source toward the solid insulator passes through the solid insulator. The transmittance measuring device measures the transmittance of the transmitted wave. If there is no abnormality inside the solid insulator, the transmittance is constant in all parts. On the other hand, when there is an abnormality such as an air gap inside the solid insulator, the transmittance of the transmitted wave changes at the abnormal part, and the transmittance of the transmitted wave also changes at the boundary part between the abnormal part and the normal part. . The change in transmittance at the boundary portion is larger than the change in transmittance at the abnormal portion. For this reason, an abnormal part is emphasized by the transmittance | permeability change of the surrounding boundary part. The detecting means detects the emphasized abnormal part. The polarization measuring device measures the polarization fluctuation of the transmitted wave. If there is no abnormality inside the solid insulator, the change of the dielectric constant tensor is zero in all parts. On the other hand, when there is an abnormality such as an electrical or mechanical strain inside the solid insulator, the dielectric constant tensor changes in the abnormal part, and the polarization plane of the transmitted wave changes in the abnormal part. The detecting means detects an abnormal part based on this change. That is, the detecting means detects an abnormal portion based on a change in the transmitted wave polarization plane due to a change in transmittance and a change in permittivity tensor.

  The method for detecting an abnormality of a solid insulator according to claim 1, wherein a wavelength that transmits the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves, and the solid insulator is irradiated with an electromagnetic wave having the selected wavelength. Wave transmittance is measured, and the abnormal part is detected based on the change in the transmittance of the abnormal part and the change in the transmittance of the boundary part between the abnormal part and the normal part. It can be emphasized by transmittance change. For this reason, detection of an abnormal part becomes easy and an abnormal part can be detected more reliably. In addition, since the electromagnetic wave having a wavelength that passes through the solid insulator among the terahertz wave, submillimeter wave, and millimeter wave is selected and used, it can be applied to more solid insulators, and versatility can be improved. For these reasons, the abnormality detection method for the solid insulator can be made more practical.

  According to another aspect of the method for detecting an abnormality of a solid insulator according to claim 2, a wavelength that is transmitted through the solid insulator is selected from terahertz waves and millimeter waves, and an electromagnetic wave having the selected wavelength is irradiated onto the solid insulator to transmit the transmitted wave. Is measured, and the abnormal part is detected based on the change of the polarization plane due to the change of the dielectric constant tensor of the abnormal part. Therefore, the abnormal part can be easily detected. For this reason, an abnormal part can be detected more reliably. In addition, since the electromagnetic wave having a wavelength that passes through the solid insulator among the terahertz wave, submillimeter wave, and millimeter wave is selected and used, it can be applied to more solid insulators, and versatility can be improved. For these reasons, the abnormality detection method for the solid insulator can be made more practical.

  Furthermore, in the method for detecting an abnormality of a solid insulator according to claim 3, a wavelength that passes through the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves, and an electromagnetic wave having the selected wavelength is irradiated to the solid insulator. , Measure the transmittance and polarization fluctuation of the transmitted wave, change the transmittance of the abnormal part, change of the transmittance of the boundary part between the abnormal part and normal part, and the polarization plane due to the change of the dielectric constant tensor of the abnormal part Therefore, the abnormal portion can be detected based on the change in the polarization plane of the transmitted wave due to the change in the transmittance and the change in the dielectric constant tensor. For this reason, two different methods are used in combination, so that the abnormal part can be detected more reliably and the reliability can be further improved. Moreover, it can respond to various abnormalities, and can improve versatility and reliability.

  According to another aspect of the abnormality detection device for a solid insulator according to claim 4, an electromagnetic wave source that irradiates the solid insulator with an electromagnetic wave having a wavelength that passes through the solid insulator among terahertz waves, submillimeter waves, and millimeter waves; A transmittance measuring device for measuring the transmittance of the transmitted wave, and a detecting means for detecting an abnormal portion based on a change in the transmittance of the abnormal portion and a change in the transmittance of the boundary portion between the abnormal portion and the normal portion. Therefore, the abnormal portion can be emphasized by the change in transmittance at the surrounding boundary portion. For this reason, detection of an abnormal part becomes easy and an abnormal part can be detected more reliably. In addition, since the electromagnetic wave having a wavelength that passes through the solid insulator among the terahertz wave, submillimeter wave, and millimeter wave is selected and used, it can be applied to more solid insulators, and versatility can be improved. For these reasons, the abnormality detector for solid insulators can be made more practical.

  In the solid insulator abnormality detecting device according to claim 5, an electromagnetic wave source that irradiates the solid insulator with an electromagnetic wave having a wavelength that passes through the solid insulator among terahertz waves, submillimeter waves, and millimeter waves; Equipped with a polarization measuring device that measures the polarization fluctuation of the transmitted wave and a detection means that detects the abnormal part based on the change of the polarization plane due to the change of the dielectric constant tensor of the abnormal part, so it is easy to detect the abnormal part can do. For this reason, an abnormal part can be detected more reliably. In addition, since the electromagnetic wave having a wavelength that passes through the solid insulator among the terahertz wave, submillimeter wave, and millimeter wave is selected and used, it can be applied to more solid insulators, and versatility can be improved. For these reasons, the abnormality detector for solid insulators can be made more practical.

  Further, in the abnormality detection device for a solid insulator according to claim 6, an electromagnetic wave source for irradiating the solid insulator with an electromagnetic wave having a wavelength that transmits the terahertz wave, submillimeter wave, and millimeter wave through the solid insulator; Transmittance measuring device that measures the transmittance of the transmitted wave, polarization measuring device that measures the polarization fluctuation of the transmitted wave of the solid insulator, the change in the transmittance of the abnormal part, and the boundary between the abnormal part and the normal part Since it has detection means to detect the abnormal part based on the change of the transmittance of the part and the change of the transmitted wave polarization plane due to the change of the dielectric constant tensor of the abnormal part, An abnormal portion can be detected on the basis of the change in. For this reason, two different methods are used in combination, so that the abnormal part can be detected more reliably and the reliability can be further improved. Moreover, it can respond to various abnormalities, and can improve versatility and reliability.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  FIG. 1 shows a first embodiment of an abnormality detection method for a solid insulator according to the present invention and an abnormality detection apparatus for carrying out the method. An abnormality detection method for a solid insulator (hereinafter simply referred to as an anomaly detection method) detects an abnormality inside the solid insulator 1 that is opaque to visible light, and is solid among terahertz waves, submillimeter waves, and millimeter waves. The wavelength that passes through the insulator 1 is selected, the electromagnetic wave of the selected wavelength is irradiated onto the solid insulator 1, the transmittance of the transmitted wave 2 is measured, the change in the transmittance of the abnormal portion, and the abnormal portion and normal An abnormal portion is detected based on a change in transmittance at a boundary portion with the portion.

  That is, the electromagnetic wave irradiated to the solid insulator 1 passes through the solid insulator 1. If there is no abnormality inside the solid insulator 1, the transmittance is constant in all parts. On the other hand, when there is an abnormality such as a gap inside the solid insulator 1, the transmittance of the transmitted wave 2 changes in the abnormal part, and the transmittance of the transmitted wave 2 also in the boundary part between the abnormal part and the normal part. Changes. For example, in an experiment in which a terahertz wave is irradiated on a sample in which a hole 25 simulating a void is formed in a polyethylene plate as the solid insulator 1 as shown in FIGS. 9 to 12, air is compared with the polyethylene portion (normal portion 1 a). The transmittance of the portion, that is, the hole 25 portion (abnormal portion 1b) was large, and the transmittance of the boundary portion 1c between the polyethylene portion and the air portion was extremely small. FIG. 12 conceptually shows the transmittance distribution of FIG. 11, where the region 12 is a region where the transmittance of the normal portion 1a appears, and the region 13 is a region where the transmittance of the abnormal portion 1b appears. Reference numeral 14 denotes a region where the transmittance of the boundary portion 1c appears.

  When the change in the transmittance of the air portion (abnormal portion 1b) and the change in the transmittance of the boundary portion 1c are compared, the transmittance of the boundary portion 1c is greatly changed, and the air portion 1b has a boundary around it. The result is emphasized by the change in transmittance of the portion 1c. This phenomenon is caused by the fact that the terahertz wave is refracted and scattered at the interface 26 between polyethylene and air, and this phenomenon is not limited to the combination of polyethylene and air in terms of materials, It is considered that the transmitted wave 2 is not limited to the terahertz wave.

  The present invention utilizes such a phenomenon, and by detecting the abnormal portion 1b based on the change in the transmittance of the abnormal portion 1b and the change in the transmittance of the boundary portion 1c between the abnormal portion 1b and the normal portion 1a, Detection can be performed while emphasizing the abnormal portion 1b. For this reason, the abnormal part 1b becomes conspicuous, and even if the change of the transmittance of the abnormal part 1b itself is slight, it can be detected without missing the abnormal part 1b.

  The detection of an abnormality of the solid insulator 1 is often aimed at finding an abnormality caused by a manufacturing defect or deterioration over time. In this case, it is only necessary to detect the presence or absence of an abnormality, and the abnormality can be accurately detected. There is often no need to measure the location or size of the occurrence. In the present invention, since the abnormal portion 1b is conspicuously detected, it is particularly suitable for detecting an abnormality of the solid insulator 1 that can achieve the object if the presence or absence of the abnormality can be detected. However, since the exact position and size of the abnormal portion 1b can be measured depending on the wavelength used, in that case, the position and size of the abnormal portion 1b may be measured.

  This abnormality detection method is implemented by, for example, an abnormality detection apparatus (hereinafter simply referred to as an abnormality detection apparatus) for the solid insulator 1 shown in FIG. In this abnormality detection apparatus, the detection means 5 is provided so that the detection of the abnormal portion 1b is automatically performed. This anomaly detection device detects an anomaly inside the solid insulator 1 that is opaque to visible light, and solid-insulates electromagnetic waves having a wavelength that passes through the solid insulator 1 among terahertz waves, submillimeter waves, and millimeter waves. An electromagnetic wave source 3 that irradiates the body 1, a transmittance measuring device 4 that measures the transmittance of the transmitted wave 2 of the solid insulator 1, a change in the transmittance of the abnormal portion 1b, and the abnormal portion 1b and the normal portion 1a. The detection means 5 which detects the abnormal part 1b based on the change of the transmittance | permeability of the boundary part 1c is provided. Further, a two-dimensional scanning device 6 is provided for moving the solid insulator 1 in a direction perpendicular to the transmitted wave 2 and perpendicular to each other.

  In the present embodiment, the electromagnetic wave source 3 includes, for example, a terahertz wave irradiation device that irradiates terahertz waves, a millimeter wave irradiation device that emits millimeter waves, and a submillimeter wave irradiation device that emits submillimeter waves. Are used properly. That is, since the wavelength of the electromagnetic wave that can be transmitted differs depending on the type of the solid insulator 1 to be inspected, an electromagnetic wave irradiation device that can select the wavelength of the electromagnetic wave that transmits the solid insulator 1 to be inspected and irradiate the electromagnetic wave of that wavelength. use. The use of the electromagnetic wave irradiation device and the selection of the wavelength to be used may be performed manually, or may be automatically performed by inputting the material of the solid insulator 1. However, if there is one electromagnetic wave irradiation device that can irradiate terahertz waves, submillimeter waves, and millimeter waves, the electromagnetic wave irradiation device may be used. Even if one terahertz wave irradiation device cannot cover all the terahertz waves in the wavelength range, a plurality of irradiation devices that irradiate terahertz waves of different wavelengths are used in combination to cover a wide wavelength range as a whole. Anyway. Similarly, even if a single millimeter wave irradiation device cannot cover the entire range of millimeter waves, a plurality of irradiation devices that emit millimeter waves of different wavelengths are used in combination to cover a wide wavelength range as a whole. You may do it. Similarly, even if one submillimeter wave irradiation device cannot cover all the submillimeter waves in the wavelength range, a plurality of irradiation devices that emit submillimeter waves of different wavelengths are used in combination to cover a wide wavelength range as a whole. You may do it. That is, an electromagnetic wave source 3 that can irradiate an electromagnetic wave having a frequency used for detection may be prepared.

  The solid insulator 1 is used, for example, in power equipment such as a high-voltage cable or a substation, and covers, for example, an insulator (polyethylene) of a CV cable (crosslinked polyethylene insulating cable) and a winding of a molded transformer. Solid insulator (epoxy), polymer insulator, bushing (silicone rubber) and the like. However, the applicable solid insulator 1 is not limited to this, and may be a solid insulator (vinyl chloride) of a vinyl chloride insulated cable, an oil-impregnated paper insulator of an OF cable, or the like.

  Examples of the material of the solid insulator 1 include polyethylene, polypropylene, tetrafluoroethylene, epoxy, silicone rubber, acrylic, polyvinyl chloride, EP rubber, and the like. However, the material of the solid insulator 1 to be inspected is not limited to these. Any solid insulator 1 that transmits terahertz waves, submillimeter waves, and millimeter waves can be inspected.

  The transmittance measuring device 4 includes, for example, a divider 7, a reflecting mirror 8, an intensity measuring device 9, and a transmittance calculating means 10. The irradiation wave 11 irradiated from the electromagnetic wave source 3 is divided by the divider 7 into a measurement wave 11a and a reference wave 11b at a predetermined ratio p. The measurement wave 11 a passes through the solid insulator 1 and enters the intensity measuring device 9. On the other hand, the reference wave 11 b is reflected by the reflection mirror 8 and enters the intensity measuring device 9 by bypassing the solid insulator 1. The measurement result of the intensity measuring device 9 is supplied to the transmittance calculating means 10.

  The two-dimensional scanning device 6 moves the solid insulator 1 in a plane perpendicular to the transmitted wave 2 and scans the transmitted wave 2 two-dimensionally along the surface of the solid insulator 1. 1 is composed of a holder for supporting 1 and a driving device for moving the holder in a two-dimensional direction. Information regarding the scanning position of the transmitted wave 2 is supplied to the detection means 5.

  The transmittance calculating means 10 and the detecting means 5 are realized by a computer, for example. That is, the transmittance calculating means 10 and the detection are detected by at least one central processing unit such as a CPU or MPU, an interface for inputting / outputting data, a computer having a memory for storing programs and data, and a predetermined control or calculation program. Means 5 is realized. That is, the central processing unit includes a control program such as an OS stored in the memory, a program that defines a procedure for calculating the transmittance based on the intensity of the transmitted wave 2 and the reference wave 11b, and a change in the transmittance of the abnormal portion 1b. The transmittance calculating means 10 and the detecting means 5 are realized by a program that defines the procedure for detecting the abnormal part 1b based on the change in the transmittance of the boundary part 1c between the abnormal part 1b and the normal part 1a, necessary data, etc. ing. Further, an output device such as a display or a printer is connected to the computer.

  When an electromagnetic wave having a wavelength selected according to the type of the solid insulator 1 is irradiated from the electromagnetic wave source 3, the transmitted wave 2 that has passed through the solid insulator 1 and the reference wave 11b that bypasses the solid insulator 1 are intensity measuring instruments. 9 and the measured intensity data is supplied to the transmittance calculation means 10. The transmittance calculating means 10 obtains the intensity I (= Ir / p) of the irradiation wave 11 from the intensity Ir of the reference wave 11b and the division ratio p of the divider 7, for example. Further, the intensity Iin (= I−Ir) of the measurement wave 11a is obtained from the intensity I of the irradiation wave 11 and the intensity Ir of the reference wave 11b, and the intensity of the transmitted wave 2 is Iout, the transmittance η = (Iin−Iout). The transmittance of the solid insulator 1 is obtained from / Iin. Next, the obtained transmittance is stored in association with the scanning position of the transmitted wave 2 supplied from the two-dimensional scanning device 6. Then, the solid insulator 1 is moved by the two-dimensional scanning device 6 to shift the position where the irradiation wave 11 hits by a predetermined distance (scan step), and the above procedure is repeated to obtain the transmittance of the solid insulator 1 at the position. . Then, for example, as shown in FIG. 2, the two-dimensional scanning device 6 sequentially moves the solid insulator 1 so that the irradiation wave 11 scans the surface of the solid insulator 1 two-dimensionally, and each position P1, P2 , ..., the transmittance of the solid insulator 1 is obtained.

  The detecting means 5 detects a region where the transmittance is changing based on the measurement result of the transmittance. For example, in the example of FIGS. 9 to 12, the transmittance of the region 13 where the transmittance of the air portion (hole portion) appears is larger than the transmittance of the region 12 where the transmittance of the polyethylene portion appears, and the boundary portion 1c. The transmittance of the region 14 in which the transmittance of 1 appears is extremely small. The detection means 5 detects that there is an abnormality based on the change in the transmittance of each of the regions 12-14. Compared with the region 13 corresponding to the air portion, the transmittance is greatly changed in the region 14 corresponding to the boundary portion 1c, which results in emphasizing the air portion. For this reason, an air part becomes conspicuous and an air part can be detected reliably. In FIG. 11, the magnitude of the transmissivity is indicated by the color density, and the darker the portion, the greater the transmissivity.

  Further, in the present invention, since the electromagnetic wave having a wavelength that passes through the solid insulator 1 is selected and used among terahertz waves, submillimeter waves, and millimeter waves, it can be applied to more solid insulators 1 and is versatile. And the practicality can be enhanced.

  In particular, in order to produce and operate a large-capacity (high operating voltage) solid-insulated power facility, it is necessary to monitor the inside of the solid insulator 1 in a non-destructive and non-contact manner. Since the abnormality in the solid insulator 1 occurs during the manufacture of the equipment and also due to aging deterioration during use of the equipment, the present invention is indispensable for using the solid insulated power equipment. Abnormalities such as voids and cracks in the solid insulator 1 can be detected.

  Next, a second embodiment of the present invention will be described. FIG. 3 shows an abnormality detection method for a solid insulator 1 according to the present invention and an abnormality detection apparatus for carrying out the method. This anomaly detection method detects an anomaly in the solid insulator 1 that is opaque to visible light, and selects and selects the wavelength that passes through the solid insulator 1 among terahertz waves, submillimeter waves, and millimeter waves. The solid insulator 1 is irradiated with a wavelength electromagnetic wave, the polarization fluctuation of the transmitted wave 2 is measured, and the abnormal portion 1b is detected based on the change of the polarization plane due to the change of the dielectric constant tensor of the abnormal portion 1b. is there.

  That is, the electromagnetic wave irradiated to the solid insulator 1 passes through the solid insulator 1. If there is no abnormality inside the solid insulator 1, the change amount of the dielectric constant tensor is zero in all parts. On the other hand, when there is an abnormality such as electrical strain, mechanical strain, or strain due to temperature non-uniformity in the solid insulator 1, the dielectric constant of the abnormal portion 1b is caused by the photoelastic effect, Pockels effect, Kerr effect, or the like. The tensor changes. Based on this change, the abnormal portion 1b is detected.

  Further description will be made based on FIG. 4. Now, as the reference wave 11, for example, a wave having a phase difference between vertical and horizontal, that is, a wave having a phase difference of 0 is applied to the solid insulator 1 exhibiting dielectric anisotropy (linear birefringence). When incident, a phase difference Γ is generated in the transmitted wave 2 due to the linear birefringence of the solid insulator 1. This corresponds to the fact that the linearly polarized light at an oblique angle of 45 degrees (FIG. 5) becomes elliptically polarized light (FIG. 6) tilted in the same direction. Since the phase difference Γ varies depending on the electric field (electrical strain) and stress (mechanical strain) generated in the solid insulator 1, it is possible to know the electric field and stress by observing the swelling of elliptically polarized light. it can.

That is, when an electric field or stress is partially applied to the solid insulator 1 in a state where no electric field or stress is applied (in this case, the dielectric constant tensor of the part where an abnormality has occurred changes according to the electric field or stress). The phase difference between the vertical and horizontal waves of the transmitted wave 2 changes from 0 to Γ due to the occurrence of an abnormality, that is, the polarization plane changes, in other words, the vertical and horizontal directions of the transmitted wave 2 of the normal portion 1a. The phase difference between the vertical and horizontal waves of the transmitted wave 2 in the part where the abnormality has occurred becomes Γ, resulting in a difference in the plane of polarization.) Or a solid insulator When an electric field or stress is applied to 1 as a whole and the electric field or stress of a part thereof changes (in this case, since the dielectric constant tensor of the part where the abnormality has occurred changes, the vertical and horizontal directions of the transmitted wave 2 are changed. The phase difference between the waves changes from Γ to Γ + α due to the occurrence of an abnormality, and the plane of polarization changes. Then, the phase difference between the vertical and horizontal waves of the transmitted wave 2 of the normal part 1a is Γ, and the phase difference between the vertical and horizontal waves of the transmitted wave 2 of the part where the abnormality occurs is Γ + α, The difference in the polarization plane occurs.) On the basis of the change in the phase difference between the longitudinal and transverse waves of the transmitted wave 2, it is possible to detect the occurrence or change of a partial electric field or stress. Thereby, the presence or occurrence of an abnormality such as an electrical strain or a mechanical strain can be detected.

  This abnormality detection method is implemented by, for example, the abnormality detection apparatus shown in FIG. In this abnormality detection apparatus, the detection means 5 is provided so that the detection of the abnormal portion 1b is automatically performed. This anomaly detection device detects an anomaly in the solid insulator 1 that is opaque to visible light. Among the terahertz wave, submillimeter wave, and millimeter wave, an electromagnetic wave having a wavelength that passes through the solid insulator 1 is detected. 1 based on the change of the polarization plane of the transmitted wave due to the change of the dielectric constant tensor of the abnormal portion 1b, the electromagnetic wave source 3 that irradiates 1, the polarization measurement device 15 that measures the polarization fluctuation of the transmitted wave 2 of the solid insulator The detection means 5 which detects the abnormal part 1b is provided. 1 is provided with a two-dimensional scanning device 6 for moving the solid insulator 1 in a direction perpendicular to the transmitted wave 2 and perpendicular to each other. The electromagnetic wave source 3, the solid insulator 1, and the two-dimensional scanning device 6 are the same as those of the abnormality detection device of FIG.

  The polarization measuring device 15 includes, for example, a polarizer 16, an analyzer 17, and a photodetector 18. The polarizer 16 is provided between the electromagnetic wave source 3 and the solid insulator 1 and converts the irradiation wave 11 into, for example, an oblique 45-degree linearly polarized wave. The analyzer 17 is provided between the solid insulator 1 and the photodetector 18 and allows the transmitted wave 2 inclined by 90 degrees with respect to the linear polarization of the polarizer 16 to pass therethrough. The photodetector 18 detects the transmitted wave 2 and supplies the signal to the detection means 5.

  The detection means 5 is realized by a computer, for example. That is, the detection means 5 is realized by at least one central processing unit such as a CPU or MPU, an interface for inputting / outputting data, a computer having a memory for storing programs and data, and a predetermined control or arithmetic program. Yes. That is, the central processing unit includes a control program such as an OS stored in the memory, a program that defines a procedure for detecting the abnormal portion 1b based on a change in the transmitted wave polarization plane due to a change in the dielectric constant tensor of the abnormal portion 1b, The detection means 5 is realized by data or the like. Further, an output device such as a display or a printer is connected to the computer.

  When an electromagnetic wave having a wavelength selected according to the type of the solid insulator 1 is irradiated from the electromagnetic wave source 3, the irradiation wave 11 is polarized by the polarizer 16 into a 45-degree oblique linearly polarized wave. The transmitted wave 2 that has passed through the solid insulator 1 enters the analyzer 17.

  If no abnormality such as electrical strain or mechanical strain has occurred in the solid insulator 1, the irradiation wave 11 is not polarized by the solid insulator 1 or transmitted to the analyzer 17. The solid insulator 1 is transmitted without being polarized. Therefore, the transmitted wave 2 cannot pass through the analyzer 17 and the transmitted wave 2 is not detected by the photodetector 18.

  On the other hand, when an abnormality such as an electrical strain or a mechanical strain occurs in the solid insulator 1, a transmitted wave is generated by a dielectric anisotropy determined according to a change in the dielectric constant tensor of the solid insulator 1. 2 polarization plane changes. Therefore, the transmitted wave 2 passes through the analyzer 17 and is detected by the photodetector 18. The detecting means 5 recognizes that the plane of polarization of the transmitted wave 2 has changed due to the output from the light detector 18, and associates the solid insulator 1 with the scanning position of the transmitted wave 2 supplied from the two-dimensional scanning device 6. Detect anomalies. Then, the solid insulator 1 is moved by the two-dimensional scanning device 6 to shift the position where the irradiation wave 11 hits by a predetermined distance, and the above procedure is repeated to observe the change of the polarization plane at the position and detect the abnormality. Then, the two-dimensional scanning device 6 sequentially moves the solid insulator 1 so that the irradiation wave 11 scans the surface of the solid insulator 1 two-dimensionally, as shown in FIG. A change in the polarization plane of the transmitted wave due to a change in the dielectric constant tensor of the body 1, that is, an abnormality is detected.

  In the present invention, the transmitted wave 2 cannot be detected for the normal portion 1a, and the transmitted wave 2 is detected only for the abnormal portion 1b. Therefore, it is easy to determine whether there is an abnormality. It can be detected reliably. A configuration in which the transmitted wave 2 is detected in the abnormal portion 1b and the transmitted wave 2 cannot be detected in the normal portion 1a, but the transmitted wave 2 cannot be detected in the abnormal portion 1b, instead of the configuration in which the transmitted portion 2 cannot be detected in the normal portion 1a. Anyway.

  Further, by relating the detection of the transmitted wave 2 to the scanning position of the transmitted wave 2 supplied from the two-dimensional scanning device 6, it is possible to detect the position where the abnormality has occurred. However, the two-dimensional scanning device 6 may be omitted. In this case, fixed-point observation is performed, but occurrence of an abnormality at the position can be detected by performing regular observation. This is effective when the position where an abnormality occurs can be predicted in advance.

  Further, in the present invention, since the electromagnetic wave having a wavelength that passes through the solid insulator 1 is selected and used among terahertz waves, submillimeter waves, and millimeter waves, it can be applied to more solid insulators 1 and is versatile. And the practicality can be enhanced.

  In particular, in order to produce and operate a large-capacity (high operating voltage) solid-insulated power facility, it is necessary to monitor the inside of the solid insulator 1 in a non-destructive and non-contact manner. Since the abnormality in the solid insulator 1 occurs during the manufacture of the equipment and also due to aging deterioration during use of the equipment, the present invention is indispensable for using the solid insulated power equipment. Abnormalities such as mechanical strain, electrical strain, and strain due to temperature nonuniformity inside the solid insulator 1 can be detected.

  In the present invention, for example, a CV cable using polyethylene as the solid insulator 1, a mold transformer using epoxy, a polymer insulator using silicone rubber, and the like can be examined. However, it is needless to say that the present invention is not limited to these electric facilities.

  For example, FIG. 7 shows an example in which the electrical equipment is applied to, for example, a molded transformer. In this example, the two-dimensional scanning device 6 is omitted. The transmitter 19 including the electromagnetic wave source 3 and the polarizer 16 and the receiver 20 including the analyzer 17 and the photodetector 18 are sandwiched between the inspection position 23 of the solid insulator 1 covering the winding 22 of the mold transformer 21. Are arranged opposite each other. The inspection position 23 is a position where an abnormal concentration of electric field or stress is likely to occur, such as an edge portion of the winding 22 (FIG. 7B). That is, it is preferable to install the transmitter 19 and the receiver 20 at a position where the abnormality of the solid insulator 1 is likely to occur, for example. By doing in this way, abnormality of the solid insulator 1 of the mold transformer 21 can be detected. Observation can be performed periodically while the mold transformer 21 is in operation. Further, observation may be performed while the mold transformer 21 is stopped.

  Currently, there is an increasing demand for the use of the solid insulator 1, for example, an all-solid substation that does not use a liquid or gas insulator is being developed. The solid insulator 1 is often opaque to visible light, and in this case, abnormalities such as internal bubbles cannot be visually observed. In addition, abnormalities such as mechanical strain, electrical strain, and strain due to temperature nonuniformity are difficult to confirm by visual inspection. Therefore, the present invention that can detect the abnormality inside the solid insulator 1 opaque to visible light in a non-destructive and non-contact manner is very useful.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention.

  For example, in the above description, the abnormal part 1b is detected based on the change in the transmittance of the abnormal part 1b and the boundary part 1c of the solid insulator 1 (FIG. 1), or the dielectric constant of the abnormal part 1b of the solid insulator 1 Although the abnormal portion 1b was detected based on the change of the transmitted wave polarization plane due to the change of the tensor (FIG. 3), the change in the transmittance of the abnormal portion 1b and the boundary portion 1c of the solid insulator 1 and the abnormal portion 1b The abnormal portion 1b may be detected based on both the change of the transmitted wave polarization plane due to the change of the dielectric constant tensor. An example of this case is shown in FIG. This anomaly detection method detects an anomaly inside the solid insulator 1 that is opaque to visible light, and selects and selects a wavelength that passes through the solid insulator 1 among terahertz waves, submillimeter waves, and millimeter waves. The solid insulator 1 is irradiated with the electromagnetic wave having the wavelength, and the transmittance and polarization fluctuation of the transmitted wave 2 are measured. The change in the transmittance of the abnormal portion 1b and the boundary portion between the abnormal portion 1b and the normal portion 1a The abnormal portion 1b is detected based on the change in the polarization plane caused by the change in the transmittance 1c and the change in the dielectric constant tensor of the abnormal portion 1b. An abnormality detection apparatus that implements this abnormality detection method detects an abnormality inside the solid insulator 1 that is opaque to visible light, and is a solid insulator of terahertz waves, submillimeter waves, and millimeter waves. An electromagnetic wave source 3 that irradiates the solid insulator 1 with an electromagnetic wave having a wavelength that transmits 1, a transmittance measuring device 4 that measures the transmittance of the transmitted wave 2 of the solid insulator 1, and a transmitted wave 2 of the solid insulator 1 Polarization measuring device 15 that measures polarization fluctuation, change in transmittance of abnormal portion 1b, change in transmittance of boundary portion 1c between abnormal portion 1b and normal portion 1a, and dielectric constant tensor of abnormal portion 1b The detection means 5 which detects the abnormal part 1b based on the change of the transmitted wave polarization plane by a change is provided.

  The abnormality detection device has, for example, a divider 24, and divides the irradiation wave 11 irradiated from the electromagnetic wave source 3 into a transmittance measurement wave 11c and a polarization fluctuation measurement wave 11d. The transmittance measuring wave 11 c is supplied to the transmittance measuring device 4 similar to that in FIG. 1, measures the transmittance of the solid insulator 1, and outputs the result to the detecting means 5. Further, the polarization fluctuation measuring wave 11d is supplied to the polarization measuring device 15 similar to that shown in FIG. 3, measures the polarization fluctuation of the solid insulator 1, and outputs the result to the detecting means 5. These measurements are performed while sequentially moving the solid insulator 1 by the two-dimensional scanning device 6.

  The detecting means 5 examines the region where the transmittance is changed based on the output of the transmittance measuring device 4, and based on the change of the transmittance, the region 13 corresponding to the abnormal portion 1b and the region 14 corresponding to the boundary portion 1c. And the abnormal portion 1b of the solid insulator 1 is detected. In parallel with this, the detection means 5 identifies the region where the change of the polarization plane is different based on the output of the polarization measuring device 15, and detects the abnormal portion 1b of the solid insulating material. That is, since the abnormal portion 1b is detected based on two different principles, the abnormal portion 1b can be detected more reliably, and the reliability can be further improved. In this case, the irradiation wave 11 is divided into the transmittance measuring wave 11c and the polarization fluctuation measuring wave 11d, and the transmittance and the polarization fluctuation of the solid insulating material are simultaneously measured. Instead, the transmittance and the polarization fluctuation may be measured one by one in order.

  In the above description, the two-dimensional scanning device 6 is used to move the solid insulator 1, but the configuration is not necessarily limited to this, and instead of moving the solid insulator 1, abnormalities are detected. You may make it move a detection apparatus. Moreover, you may make it move both the solid insulator 1 and an abnormality detection apparatus.

  An experiment was performed in which a terahertz wave was irradiated to a sample of the solid insulator 1 and bubbles were detected based on a change in transmittance. A polyethylene plate having a thickness of 5 mm was used as a sample of the solid insulator 1 used in the experiment. In Sample 1, as shown in FIG. 9, holes 25 having a diameter of 10 mm and holes 25 having an diameter of 8 mm were formed with an interval of 8 mm. As the irradiation wave 11, a terahertz wave having a frequency of 1.3 THz was used. A backward traveling wave tube (BWO tube) was used as the electromagnetic wave source 3 for generating the terahertz wave. Scan area: 37.3 mm (X direction) × 28.2 mm (Y direction), scan step: 0.54 mm.

  The results of the experiment are shown in FIGS. FIG. 10 shows the transmitted light intensity at a position along the LL dotted line in FIG. A broken line A in FIG. 10 indicates an average level of a portion other than the hole 25. Moreover, in FIG. 11, the magnitude of the transmittance is shown by the color density, and the darker the portion, the higher the transmittance. FIG. 12 conceptually shows the transmittance distribution of FIG.

  The transmittance of the hole 25 portion (abnormal portion 1b) is larger than that of the polyethylene portion (normal portion 1a), and the transmittance is drastically reduced at the edge of the hole 25 (interface between air and polyethylene). 26 was observed with emphasis. This phenomenon seems to be due to the terahertz wave being refracted and scattered at the interface 26 between air and polyethylene. It is considered that the same phenomenon is observed in the actual solid insulator 1 when an abnormal portion 1b such as a bubble or a crack exists inside. Thereby, it was confirmed that abnormal portions 1b such as bubbles and cracks in the solid insulator 1 could be detected.

  An experiment was conducted in which mechanical stress generated in the solid insulator 1 was detected based on a change in polarization plane of the transmitted wave 2 due to a change in dielectric constant tensor. As a sample of the solid insulator 1, a polyethylene piece having a thickness of 5 mm was used. As shown in FIG. 13, the sample 1 was partially sandwiched by the clamping device 27 to generate a partial mechanical stress on the sample 1. In FIG. 13, the P circle indicates a mechanical stress application portion. As the irradiation wave 11, a terahertz wave having a frequency of 1 THz was used. The polarizer 16 was used to make the irradiation wave 11 linearly polarized at an angle of 45 degrees, and the analyzer 17 inclined by 90 degrees with respect to the polarizer 16 was used. For comparison, an experiment was performed without using the polarizer 16 and the analyzer 17.

  The result of the experiment is shown in FIG. In FIG. 14, the white rectangle is the sample 1, and the outline of the clamp device 27 is indicated by a white line on both sides of the sample 1 in FIG. FIG. 14A shows the results when the polarizer 16 and the analyzer 17 are not used, and FIG. 14B shows the results when the polarizer 16 and the analyzer 17 are used. In the experiment in which the polarizer 16 and the analyzer 17 were not used, the transmittance of the terahertz wave was large in the air portion other than the sample 1 and the clamp device 27, and the terahertz wave was not transmitted through the metal portion (clamp device 27 portion). It was only confirmed that a polyethylene part (sample 1 part) permeate | transmits so that there was a terahertz wave (FIG. 14 (A)).

  On the other hand, when the irradiation wave 11 on the sample 1 is linearly polarized at an angle of 45 degrees by the polarizer 16 and the transmitted wave 2 is detected through the analyzer 17 in a direction inclined by 90 degrees, the transmitted wave 2 is observed only at the stressed portion. It was done. This is because the portion other than the stress generation portion of sample 1 does not change the polarization state of irradiation wave 11, and transmitted wave 2 cannot pass through analyzer 17, but the stress generation portion of sample 1 is transmitted wave 2 due to the photoelastic effect. This is because a component that can be transmitted through the analyzer 17 is generated. In this experiment, the mechanical stress (mechanical strain) is generated in the sample 1, but the same applies to the case where electrical strain, strain due to temperature nonuniformity, and the like are generated. Thereby, it was confirmed that abnormalities such as mechanical strain, electrical strain, strain due to temperature nonuniformity, etc. in the solid insulator 1 could be detected.

  An experiment was conducted to examine the transmission characteristics of terahertz waves to polyethylene, which is a typical solid insulator 1. A polyethylene plate having a thickness of 5 mm was used as an experimental sample. Experiments were performed on terahertz waves of about 0.85 to 1.1 THz and about 1.2 to 1.4 THz. The result is shown in FIG. As a result, it was found that terahertz waves transmitted through polyethylene well. For this reason, it has confirmed that abnormality in polyethylene was detectable using a terahertz wave. Note that the transmittance vibration in FIG. 15 is due to the etalon effect.

  Experiments were conducted to examine the transmission characteristics of submillimeter waves and millimeter waves with respect to typical solid insulators 1 such as epoxy and silicone rubber. As an experimental sample, an epoxy plate and a silicone rubber plate having a thickness of 5 mm were used. The result is shown in FIG. Although terahertz waves can hardly pass through epoxy or silicone rubber, it has been confirmed that transmission becomes possible when the wavelength is increased (lower frequency), that is, in the submillimeter wave band and the millimeter wave band. For this reason, it was confirmed that abnormalities in epoxy and silicone rubber could be detected using submillimeter waves and millimeter waves.

  However, the measurement resolution (in the plane perpendicular to the traveling direction of the submillimeter wave and millimeter wave) is determined by the length of the wavelength, so if the wavelength is too long, the resolution deteriorates and may not be suitable for high-precision detection. There is also sex. In particular, for highly accurate detection, it is necessary to select the wavelength of the irradiation wave 11 in consideration of the balance between transmittance and resolution.

1 is a block diagram illustrating a first embodiment of an abnormality detection device for a solid insulator according to the present invention. It is a figure for demonstrating the two-dimensional scanning of a solid insulator. It is a block diagram which shows 2nd Embodiment of the abnormality detection apparatus of the solid insulator of this invention. It is a figure for demonstrating the phase difference change (generation | occurrence | production) between the vertical and horizontal waves by the solid insulator which has anisotropy in a dielectric constant tensor. It is a figure which shows 45-degree diagonal linearly polarized light. It is a figure which shows the elliptically polarized light of diagonal 45 degree | times. The 3rd Embodiment of the abnormality detection apparatus of the solid insulator of this invention is shown notionally, (A) is the whole figure, (B) is the concept of a plane perpendicular | vertical to the transmitted wave in the B circle part of (A). FIG. It is a block diagram which shows 4th Embodiment of the abnormality detection apparatus of the solid insulator of this invention. It is a top view of the sample used in the experiment which detects a bubble. It is a graph which shows the result of the experiment which detects a bubble and shows the transmitted light intensity of the position along the LL dotted line of FIG. It is the figure which showed the result of the experiment which detects a bubble and showed distribution of the transmittance | permeability two-dimensionally. It is the figure which showed notionally the distribution of the transmittance | permeability of FIG. It is a schematic block diagram which shows the mode of the experiment which detects a mechanical stress. The result of the experiment which detects mechanical stress is shown, (A) is a figure which shows distribution of the transmittance | permeability when not using a polarizer and an analyzer, (B) is the transmittance | permeability when a polarizer and an analyzer are used. FIG. It is a graph which shows the relationship between the frequency at the time of irradiating a terahertz wave to polyethylene, a transmittance | permeability, and an absorption coefficient. It is a graph which shows the relationship between the frequency at the time of irradiating a terahertz wave, a submillimeter wave, and a millimeter wave to an epoxy and silicone rubber, a transmittance | permeability, and an absorption coefficient. It is a conceptual diagram of the difference imaging apparatus using the conventional terahertz wave.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid insulator 1a Normal part 1b Abnormal part 1c Boundary part 2 Transmitted wave 3 Electromagnetic wave source 4 Transmittance measuring device 5 Detection means 15 Polarization plane measuring device

Claims (6)

  In the abnormality detection method for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, a wavelength that passes through the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves. The solid insulator is irradiated with an electromagnetic wave having a wavelength, and the transmittance of the transmitted wave is measured. Based on the change in the transmittance of the abnormal part and the change in the transmittance of the boundary part between the abnormal part and the normal part, A method for detecting an abnormality of a solid insulator, characterized by detecting an abnormal part.   In the abnormality detection method for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, a wavelength that passes through the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves. The solid insulator is irradiated with an electromagnetic wave having a wavelength, a polarization fluctuation of a transmitted wave is measured, and the abnormal portion is detected based on a change in a polarization plane due to a change in a dielectric constant tensor of the abnormal portion. Abnormality detection method for solid insulators.   In the abnormality detection method for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, a wavelength that passes through the solid insulator is selected from terahertz waves, submillimeter waves, and millimeter waves. Irradiate the electromagnetic wave of the wavelength to the solid insulator, measure the transmittance and polarization fluctuation of the transmitted wave, change the transmittance of the abnormal part, and change of the transmittance of the boundary part between the abnormal part and the normal part And detecting an abnormal portion based on a change in polarization plane caused by a change in dielectric constant tensor of the abnormal portion.   In an abnormality detection apparatus for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, an electromagnetic wave having a wavelength that passes through the solid insulator among terahertz waves, submillimeter waves, and millimeter waves is solid-insulated. An electromagnetic wave source that irradiates the body, a transmittance measuring device that measures the transmittance of the transmitted wave of the solid insulator, a change in the transmittance of the abnormal portion, and a transmittance of the boundary portion between the abnormal portion and the normal portion An apparatus for detecting an abnormality of a solid insulator, comprising detecting means for detecting the abnormal part based on a change.   In an abnormality detection apparatus for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, an electromagnetic wave having a wavelength that passes through the solid insulator among terahertz waves, submillimeter waves, and millimeter waves is solid-insulated. An electromagnetic wave source that irradiates the body, a polarization measurement device that measures the polarization fluctuation of the transmitted wave of the solid insulator, and the abnormal part is detected based on a change in polarization plane due to a change in the dielectric constant tensor of the abnormal part An abnormality detection apparatus for a solid insulator comprising a detection means.   In an abnormality detection apparatus for a solid insulator that detects an abnormality inside a solid insulator that is opaque to visible light, an electromagnetic wave having a wavelength that passes through the solid insulator among terahertz waves, submillimeter waves, and millimeter waves is solid-insulated. An electromagnetic wave source for irradiating the body, a transmittance measuring device for measuring the transmittance of the transmitted wave of the solid insulator, a polarization measuring device for measuring the polarization fluctuation of the transmitted wave of the solid insulator, and an abnormal portion Detection means for detecting the abnormal portion based on a change in transmittance, a change in transmittance at a boundary portion between the abnormal portion and the normal portion, and a change in polarization plane due to a change in dielectric constant tensor of the abnormal portion. An abnormality detection device for a solid insulator characterized by the above.