JP5802991B2 - Insulation resistance measuring device - Google Patents

Description

  The present invention relates to an insulation resistance measuring apparatus for measuring an insulation resistance of an insulator of an electric device.

  In general, the insulation resistance value of an insulator of an electric device is as high as that of a new product, and tends to decrease with age. Therefore, grasping the current insulation resistance is the same as grasping the quality of the insulators that make up the electrical equipment, and is useful for grasping the replacement timing of the electrical equipment. It is a measurement that must be carried out during regular inspections of private electrical works. In addition, since there is a risk of causing a ground fault if the insulation resistance value is extremely lowered, insulation resistance measurement is an extremely important measurement item from the viewpoint of preventing electrical accidents.

  For example, unsaturated polyester is used as an insulating material for circuit breakers and switches in high-voltage power receiving equipment. The number of defects indicated for equipment using insulating polyester as an insulating material is about 60% of the total, which is the highest compared to electrical equipment using other insulating materials (insulating oil, cross-linked polyethylene, etc.). It is an important management item to maintain the maintenance of the entire equipment. In general, the insulation resistance of an electrical equipment insulator is determined by applying a voltage measurement voltage to the electrical equipment insulation by stopping energization of the electrical equipment and determining the resistance value of the measurement object based on the current flowing through the insulation. Measurement is performed (see, for example, Patent Document 1).

JP 2010-8401 A

  However, since the insulation resistance of the insulator of the electrical equipment is performed by stopping energization of the electrical equipment, the facility operation rate is reduced due to a power failure. In addition, since the voltage measurement voltage is applied to the insulator of the electric equipment, the measurement instrument is brought into contact with the electric circuit, which may cause an electric shock accident due to an erroneous operation.

  It is an object of the present invention to measure an insulation resistance value in a non-contact state while energizing an electrical device, and to improve the operating rate of equipment, improve the workability of inspection work, and improve safety. It is to provide a measuring device.

An insulation resistance measuring device according to the invention of claim 1 is a storage device that stores in advance a relational expression between a discharge sound intensity of an insulator of an electrical device in an energized state and a surface insulation resistance value of the insulator; A discharge sound detector for detecting a discharge sound of an insulator of an electric device, and a vibration for extracting a frequency component of the discharge sound by using a fast Fourier transform or a band-pass filter for the discharge sound detected by the discharge sound detector Sound component extraction means; and resistance calculation means for obtaining a surface insulation resistance value of the insulator based on the discharge sound intensity in the frequency domain of the characteristic extracted by the vibration sound component extraction means and the relational expression stored in the storage device; It is provided with.

An insulation resistance measuring device according to the invention of claim 2 is a storage device that stores in advance a relational expression between the discharge sound intensity of an insulator of an electrical device in an energized state and the surface insulation resistance value of the insulator; A discharge sound detector for detecting a discharge sound of an insulator of an electric device, and a vibration for extracting a frequency component of the discharge sound by using a fast Fourier transform or a band-pass filter for the discharge sound detected by the discharge sound detector A sound component extracting unit; a photographing device that photographs the electrical device; a discharge determining unit that analyzes an image photographed by the photographing device to determine the presence or absence of discharge light emission; and a characteristic extracted by the vibration sound component extracting unit. A resistance calculation means for obtaining a surface insulation resistance value of the insulator based on a discharge sound intensity in a frequency domain and a relational expression stored in the storage device; and when the discharge determination means determines that there is discharge light emission, the resistance Wherein the surface insulation resistance value obtained by the calculation means comprising a determining whether the computed resistance value confirmation unit is less than a predetermined value determined in advance.

The insulation resistance measuring apparatus according to the invention of claim 3 is the invention of claim 1 or 2,
The relational expression is that a plurality of insulators having different known surface insulation resistance values are prepared, a predetermined voltage is applied to each of the prepared insulators, a discharge sound is detected by a discharge sound detector, and the discharge sound is detected. Using the fast Fourier transform or bandpass filter for the discharge sound measured by the detector, the discharge sound intensity in a specific frequency region where the discharge sound intensity is high is extracted, and the correlation between the extracted discharge sound intensity and the surface insulation resistance value It is obtained beforehand based on a graph.

  According to a fourth aspect of the present invention, there is provided the insulation resistance measuring apparatus according to any one of the first to third aspects, wherein the insulator is unsaturated polyester, porcelain, or acrylic.

  According to the first aspect of the present invention, the relational expression between the discharge sound intensity of the insulator of the electric device in the energized state and the surface insulation resistance value of the insulator is stored in advance, and the discharge of the insulator of the electric device is stored. Since the sound is detected to extract the discharge sound intensity in the characteristic frequency domain and the surface insulation resistance value of the insulator is obtained based on the discharge sound intensity and the relational expression, the insulation resistance can be grasped in a non-contact manner. Accordingly, since the insulation resistance can be detected in the energized state of the electric equipment, the operating rate of customer facilities can be improved and the workability of inspection work can be improved.

  According to the second aspect of the present invention, the presence or absence of discharge light emission is determined by analyzing an image of an electrical device, and when it is determined that there is discharge light emission, the insulation obtained based on the discharge sound intensity and the relational expression Since it is determined whether or not the surface insulation resistance value is equal to or less than a predetermined value and the calculated surface insulation resistance value is confirmed, the accuracy of the obtained insulation resistance is improved.

  According to the invention of claim 3, a plurality of insulators having different known surface insulation resistance values are prepared, and for each of the prepared insulators, a discharge sound intensity and a surface insulation resistance value and a relational expression are obtained. An accurate relationship between the discharge sound intensity and the surface insulation resistance value can be obtained.

  According to invention of Claim 4, an insulation resistance can be measured with respect to insulators, such as unsaturated polyester, porcelain, and an acryl.

  According to the invention of claim 5, the frequency component of the discharge sound detected by the discharge sound detector can be extracted even if a band pass filter is used instead of the fast Fourier transform.

The block diagram of the insulation resistance measuring apparatus which concerns on the 1st Embodiment of this invention. The graph which developed the number of indications of insulation decrease of unsaturated polyester and the average humidity every month. The graph which shows the prediction result of a cumulative equivalent salt adhesion amount and the number of months. The photograph of the creeping discharge sound spectrum of the frequency component in each insulation resistance value when the insulation resistance value is gradually decreased from 100 MΩ to 0.1 MΩ when the equivalent salt content is 0.044 mg / cm ² . Correlation graph between insulation resistance value and discharge sound intensity with frequency as parameter. The photograph figure of the creeping discharge sound spectrum of the frequency component in the insulator of the real machine under high voltage charge. The block diagram of the insulation resistance measuring apparatus which concerns on the 2nd Embodiment of this invention. The photograph figure of the discharge generation | occurrence | production image of the insulator in each insulation resistance value when the insulation resistance value in the equivalent salt adhesion amount is 0.044 mg / cm ² is gradually decreased from 100 MΩ to 0.1 MΩ. The graph which shows the relationship between the insulation resistance value which has confirmed discharge light emission, and an equivalent salt content. The photograph of the creeping discharge sound spectrum of the frequency component in the case of the unsaturated polyester whose resistance value is 1 MΩ as an insulator, a high voltage pin, and an acrylic.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of an insulation resistance measuring apparatus according to the first embodiment of the present invention. The insulation resistance measuring device is composed of a computer, for example, a personal computer. That is, the function block shown in FIG. 1 is installed when a program is installed in a computer including the input device 11, the arithmetic control device 12, the storage device 13, and the display device 14, and the arithmetic control device 12 executes the program. Is realized. A discharge sound detector 15 is connected to the arithmetic control device 12.

  The input device 11 is a keyboard, a mouse, or the like, and inputs various commands such as an operation command to the arithmetic control device 12 and an output command to the display device 14. The discharge sound detector 15 detects sound such as a microphone, for example. In the embodiment of the present invention, the discharge sound detector 15 is installed in the vicinity of the insulator of the electric device and detects the discharge sound of the insulator of the electric device. Since a voltage is applied to the insulator of the electrical equipment that is energized and a discharge occurs when the insulator is deteriorated, the discharge sound detector 15 generates a discharge sound when the discharge occurs. To detect.

  The discharge sound detected by the discharge sound detector 15 is input to the input processing unit 16 of the arithmetic control device 12 and is stored in the storage device 13 as a time-series digital signal and also input to the vibration sound component extraction means 17. The The vibration sound component extraction means 17 performs fast Fourier transform on the discharge sound detected by the discharge sound detector 15 to extract the frequency component of the discharge sound, and extracts a frequency component having a high discharge sound intensity. The discharge sound in the frequency domain of the characteristic extracted by the vibration sound component extraction means 17 is input to the resistance calculation means 18 and stored in the storage device 13 as necessary.

  When the resistance calculation means 18 inputs the discharge sound in the frequency domain of the characteristic extracted by the vibration sound component extraction means 17, the resistance calculation means 18 substitutes the discharge sound intensity into the relational expression stored in advance in the storage device 13, and the surface of the insulator The insulation resistance value is calculated, and the calculation result is displayed on the display device 14 via the output processing unit 19. Thereby, the insulation resistance value of the insulator is displayed on the display device 14.

  Here, the storage device 13 stores in advance a relational expression between the discharge sound intensity of the insulator of the electrical device that is energized and the surface insulation resistance value of the insulator. The relational expression between the discharge sound intensity and the surface insulation resistance value is obtained in advance as follows.

  First, a plurality of insulators having different known surface insulation resistance values are prepared. And a predetermined voltage is applied with respect to each prepared insulator, and a discharge sound is detected with a discharge sound detector. Thereby, discharge sound data for each insulator having different surface insulation resistance values can be obtained. Then, the discharge sound data for each insulator having different surface insulation resistance values is subjected to fast Fourier transform to extract the discharge sound intensity in a specific frequency region where the discharge sound intensity is high. As a result, a correlation graph is obtained in which the discharge sound intensity and the surface insulation resistance value are plotted with a specific frequency having a high discharge sound intensity as a parameter. From this correlation graph, a relational expression between the discharge sound intensity and the surface insulation resistance value of the insulator is obtained.

(1) Regarding preparation of a plurality of insulators having different known surface insulation resistance values First, the insulator targeted in the present invention is unsaturated polyester, and the deterioration factors of this unsaturated polyester are as follows: Conceivable. The unsaturated polyester surface is considered to have the property of ionizing when calcium carbonate deposited by hydrolysis under high humidity conditions comes into contact with NOx and SOx in the atmosphere.

2NO ₂ + H ₂ O → HNO ₃ + HNO ₂
CaCO ₃ + 2HNO ₃ → Ca (NO ₃ ) ₂ + H ₂ O + CO ₂
Ca (NO ₃ ) ₂ is a deliquescent ionized compound and is considered to cause a decrease in insulation under high humidity conditions. FIG. 2 is a graph in which the number of insulation deterioration indications and the average humidity of the unsaturated polyester are expanded by month. The bar graph shows the number of insulation deterioration indications, and the line graph shows the average humidity.

Normally, devices such as circuit breakers and switches in high-voltage power receiving equipment are housed in distribution boxes and are not exposed to direct wind and rain, but are structured to easily take in outside air, and have external humidity. It is thought that it is easy to be affected. As can be seen from FIG. 2, the number of indications of insulation decrease correlates with the average humidity, and it is thought that the above-mentioned deterioration factor results due to precipitation of the ionized compound Ca (NO ₃ ) ₂ and humidity. .

  Therefore, a plurality of insulators having different known surface insulation resistance values were prepared as follows. A high-voltage AC load switch (LBS) that was used in customer facilities was prepared as an experimental sample. Usually, high-voltage AC load switches are used as main switches for overload protection of transformers and small-capacity power receiving equipment, and unsaturated polyester is used for the insulation.

  Based on the measurement results on the cubicle structure and pollution in JEM-TR194 “Guidelines for Examining High-Voltage Circuit Breaker Usage Conditions”, JEM-TR194, the Japan Electrical Manufacturers' Association Technical Report A three-month regression line was obtained and predicted. FIG. 3 is a graph showing a prediction result of the accumulated equivalent salt adhesion amount and the number of months. A curve S1 is a curve of the accumulated equivalent salt adhesion amount in the case of forced ventilation, and a curve S2 is a curve of the accumulated equivalent salt adhesion amount in the case of natural ventilation.

Based on Fig. 3, according to the change in the amount of equivalent salt deposits every 12 months from 12 months to 60 months, uniformly apply a salt solution with a concentration according to the surface area of the sample insulator and then dry. Confirm that the insulation resistance has recovered sufficiently. Next, purified water was sprayed on the part to which the salt was adhered to obtain a predetermined insulation resistance value. Table 1 shows the amount of equivalent salinity deposited in the experiment.

(2) Detection of discharge sound When it is confirmed that the insulation resistance value is stable, a predetermined voltage AC3810V is applied to both ends thereof. And the discharge sound immediately after application is measured. In the experiment, a discharge sound was recorded when the insulation resistance value was gradually decreased for the accumulated equivalent salt adhesion amount every 12 months for each ventilation method. The discharge sound was measured using a discharge sound detector capable of digital recording, and the sampling frequency was 96 kHz.

FIG. 4 is a photograph of a creeping discharge sound spectrum of frequency components at each insulation resistance value when the insulation resistance value is gradually decreased from 100 MΩ to 0.1 MΩ at an equivalent salt adhesion amount of 0.044 mg / cm ² . The vertical axis represents frequency × 10 ⁴ [Hz], and the horizontal axis represents time [sec]. The frequency component that appears vertically around 0.6 seconds on the horizontal axis (time axis) of 0.1 MΩ is the circuit breaker sound.

(3) Extraction of discharge sound intensity in specific frequency region and relational expression Next, in order to investigate what frequency component is included in the measured discharge sound, the discharge sound intensity is obtained by fast Fourier transform. The discharge sound intensity in a large specific frequency region was extracted.

  FIG. 5 is a correlation graph between the insulation resistance value and the discharge sound intensity with the frequency as a parameter. In Fig. 5, 10kHz to 15kHz components, which showed particularly strong characteristics in experiments, were extracted, and the change in discharge sound intensity when the insulation resistance value was reduced from 100MΩ to about 0.1MΩ was plotted using the frequency as a parameter. Is shown. The curve is a power approximation curve of the measured value at each frequency.

  As a result of visualizing creeping discharge sound by fast Fourier transform FFT, it was found that the characteristics always appeared in the audible frequency region even when the amount of equivalent salt deposition was changed.

FIG. 6 is a photograph of a creeping discharge sound spectrum of frequency components in an actual insulator during high voltage charging. The vertical axis represents frequency × 10 ⁴ [Hz], and the horizontal axis represents time [sec]. As can be seen from Fig. 6, when measuring creeping discharge noise due to natural degradation in an actual machine, the surface moisture content during creeping discharge is reduced, so in the frequency range lower than the 10kHz to 15kHz component in the experiment (artificial fouling). Extraction of components from 5kHz to 10kHz, especially when natural deterioration is remarkable, it was found effective to extract components from 8kHz to 9kHz and perform deterioration diagnosis.

  Although there was no significant change in the frequency band where the characteristics appeared even with changes in the surface insulation resistance value, focusing on the fact that the discharge sound intensity changed, the insulation resistance value and the discharge sound were calculated based on the power approximation curve. A relational expression with strength was derived. As the insulation resistance value increases logarithmically, the discharge sound intensity tends to decrease linearly, and fitting by a power function is most suitable. That is, the approximate expression is expressed as the following expression (1), where the discharge sound intensity is W [dB] and the surface insulation resistance value is R [MΩ].

W = aR− ^b (1)
Table 2 shows the constants a and b and the R-2 power of equation (1) for each equivalent salt adhesion amount ESDD.

  The constant a is a constant determined by the magnitude of the detection gain of the discharge sound detector. The constants a and b are substituted into the equation (1) to obtain a relational expression between the discharge sound intensity and the surface insulation resistance value of the insulator, which is stored in the storage device 13 in advance.

  In the above description, the vibration sound component extracting means 17 performs the fast Fourier transform on the discharge sound detected by the discharge sound detector 15 and extracts the frequency component of the discharge sound. The frequency component of the discharge sound may be extracted using a pass filter.

  According to the first embodiment, a relational expression between the discharge sound intensity of the insulator of the electrical device and the surface insulation resistance value of the insulator is stored in the storage device 13 in advance, and the discharge sound of the insulator of the electrical device is stored. By detecting and extracting the discharge sound intensity in the frequency domain of the characteristic and obtaining the surface insulation resistance value of the insulator based on the discharge sound intensity and the relational expression, the insulation resistance can be grasped in a non-contact manner. As a result, it is possible to improve the operating rate of customer facilities, improve the workability of inspection work, and improve safety.

  Next, a second embodiment of the present invention will be described. FIG. 7 is a configuration diagram of an insulation resistance measuring apparatus according to the second embodiment of the present invention. This second embodiment is different from the first embodiment shown in FIG. 1 in that a photographing device 20 that photographs an electrical device and a discharge that analyzes the image photographed by the photographing device 20 and determines the presence or absence of discharge light emission. When the determination means 21 and the discharge determination means 21 determine that there is discharge light emission, it is determined whether or not the surface insulation resistance value obtained by the resistance calculation means 18 is equal to or less than a predetermined value. Means 22 are additionally provided. The same elements as those in FIG.

  The imaging device 20 is, for example, a CCD camera or a high-sensitivity video amplification tube, and captures an external image of an electrical device. The reason why the appearance image of the electric device is photographed is to detect light emission due to discharge.

FIG. 8 is a photograph of an image of discharge occurrence of an insulator at each insulation resistance value when the insulation resistance value is gradually reduced from 100 MΩ to 0.1 MΩ at an equivalent salt adhesion amount of 0.044 mg / cm ² . It can be seen that the discharge emission becomes clearer as the insulation resistance value decreases.

  An image photographed by the photographing device 20 is input to the discharge determination means 21 via the input processing unit 16. The discharge determination unit 21 analyzes an image captured by the imaging device 20 and determines the presence or absence of discharge light emission. In the discharge occurrence image of the insulator, since the discharge is generated at a portion having a high brightness, it is determined whether there is a discharge light emission by determining whether there is a portion having a high brightness on the surface of the insulator.

  Next, a graph was created by plotting the insulation resistance value at which discharge light emission was confirmed for each equivalent salt content. FIG. 9 is a graph showing the relationship between the insulation resistance value at which discharge light emission was confirmed and the equivalent salt content. In FIG. 9, it was found that the insulation resistance value at which discharge occurs tends to be substantially constant with the increase in the amount of equivalent salt adhesion. That is, it can be said that the insulation resistance value at which creeping discharge starts does not change even when the equivalent salt content on the surface of the insulator increases with time.

  At the same time, when the insulation resistance value on the surface of the insulator is 100 MΩ, it can be seen that creeping discharge does not occur at all equivalent salt deposits, and maintenance of the switchgear equipment by controlling the insulation resistance value is less than about 30 MΩ. It became clear that the need for implementation would increase.

  Therefore, since the discharge is generated at about 30 MΩ, when the discharge determination means 21 detects that the discharge has occurred, the calculated resistance value confirmation means 22 determines the surface insulation resistance obtained by the resistance calculation means 18. Determine if the value is about 30MΩ. That is, 30 MΩ is set in advance as a predetermined value, and the calculated resistance value confirmation unit 22 determines whether the surface insulation resistance value obtained by the resistance calculation unit 18 is 30 MΩ or less. When it is 30 MΩ or less, it is determined that the surface insulation resistance value obtained by the resistance calculation means 18 is appropriate.

  On the other hand, when it is 30 MΩ or more, it is determined that the surface insulation resistance value obtained by the resistance calculating means 18 is not appropriate. Then, the determination result is displayed on the display device 14 via the output processing unit 19. When it is determined that the surface insulation resistance value obtained by the resistance calculation means 18 is not appropriate, the constants a and b in the equation (1) may not be set appropriately. b will be reviewed.

  According to the second embodiment, an image of an electrical device is analyzed to determine the presence or absence of discharge light emission, and when it is determined that there is discharge light emission, the insulating material obtained based on the discharge sound intensity and the relational expression is determined. Since it is determined whether or not the surface insulation resistance value is appropriate, the accuracy of the obtained insulation resistance is improved.

  In the above description, the case where the insulating material is unsaturated polyester has been described. However, the present invention can be similarly applied to the case where the high-pressure pin is an insulator or acrylic. FIG. 10 is a photograph of the creeping discharge sound spectrum of the frequency component in the case where the insulator is an unsaturated polyester having a resistance value of 1 MΩ, a high-pressure pin, and acrylic. The frequency component that appears vertically in the vicinity of 0.3 seconds on the high-pressure pin insulator and the horizontal axis (time axis) of acrylic is the input sound of the circuit breaker.

  It was found that a strong spectrum appeared in the 8 kHz to 15 kHz component, which is the audible frequency range, with the high-voltage pin insulator, and that the characteristics appeared in the audible frequency band in the acrylic as well. As a result, it is possible to detect a decrease in insulation due to the audible region not only for unsaturated polyester but also for insulators such as porcelain.

DESCRIPTION OF SYMBOLS 11 ... Input device, 12 ... Arithmetic controller, 13 ... Memory | storage device, 14 ... Display apparatus, 15 ... Discharge sound detector, 16 ... Input processing part, 17 ... Vibration sound component extraction means, 18 ... Resistance calculation means, 19 ... Output processing unit, 20 ... photographing apparatus, 21 ... discharge determining means, 22 ... calculated resistance value checking means

Claims (4)

A storage device that stores in advance a relational expression between a discharge sound intensity of an insulator of an electric device that is energized and a surface insulation resistance value of the insulator, and a discharge sound that detects a discharge sound of the insulator of the electric device A detector, a vibration sound component extracting means for extracting a frequency component of the discharge sound using a fast Fourier transform or a bandpass filter for the discharge sound detected by the discharge sound detector, and the vibration sound component extracting means. An insulation resistance measuring device comprising: resistance calculation means for obtaining a surface insulation resistance value of the insulator based on the discharge sound intensity in the frequency domain of the extracted characteristic and the relational expression stored in the storage device. A storage device that stores in advance a relational expression between a discharge sound intensity of an insulator of an electric device that is energized and a surface insulation resistance value of the insulator, and a discharge sound that detects a discharge sound of the insulator of the electric device Detector, vibration sound component extracting means for extracting frequency component of discharge sound using fast Fourier transform or bandpass filter for discharge sound detected by discharge sound detector, and photographing for photographing electric device Apparatus, discharge determination means for analyzing the image taken by the photographing apparatus to determine the presence or absence of discharge light emission, discharge sound intensity in the frequency domain of the characteristic extracted by the vibration sound component extraction means, and stored in the storage device A resistance calculation means for obtaining a surface insulation resistance value of the insulator based on a relational expression, and a surface insulation resistance value obtained by the resistance calculation means when the discharge determination means determines that there is discharge light emission in advance. Meta insulation resistance measuring apparatus characterized by comprising a determining operation resistance check means if it is less than a predetermined value. The relational expression is that a plurality of insulators having different known surface insulation resistance values are prepared, a predetermined voltage is applied to each of the prepared insulators, a discharge sound is detected by a discharge sound detector, and the discharge sound is detected. Using the fast Fourier transform or bandpass filter for the discharge sound measured by the detector, the discharge sound intensity in a specific frequency region where the discharge sound intensity is high is extracted, and the correlation between the extracted discharge sound intensity and the surface insulation resistance value 3. The insulation resistance measuring apparatus according to claim 1, wherein the insulation resistance measuring apparatus is obtained in advance based on a graph.   The insulation resistance measuring apparatus according to any one of claims 1 to 3, wherein the insulator is unsaturated polyester, porcelain, or acrylic.