Defect Detection Device

Abstract

To provide a contamination detection device with which it is possible to estimate the contamination degree of an insulated substance with good accuracy that is installed inside of an electric facility, etc.SOLUTION: The contamination detection device includes: an electrode substrate where a pair of electrodes are formed on an insulating substrate; a humidity sensor for measuring humidity and provided on the electrode substrate; recording means for recording an electrode resistance value between the pair of electrodes and the humidity measured by the humidity sensor at a prescribed time interval, respectively; extraction means for extracting, from among the recorded electrode resistance values and humidity data, the highest value of humidity corresponding to an electrode resistance value that is lower than or equal to a threshold, as a humidity transition highest value, in a time range from a given time earlier to the present point of time; average calculation means for picking up n humidity transition highest values in ascending order of humidity out of the extracted humidity transition highest values and calculating the average value of these; and contamination amount estimation means for estimating a contamination amount on the basis of the calculated average value and preliminarily stored contamination amount estimation information.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a contamination detection device, and more particularly to a technique suitable for detecting contamination of an insulator installed inside electrical equipment or the like.

Background Art

[0002] When an insulator such as an insulator is contaminated by salt adhering to its surface, its insulation property deteriorates. When the power generation and transmission equipment where the insulator is installed is in a saline area, since salt easily adheres, a decrease in insulation property is particularly feared. Therefore, it is necessary to always grasp the degree of contamination of an insulator such as an insulator and perform cleaning at a necessary time.

[0003] Various methods for detecting the degree of contamination of an insulator have been proposed. As one of such methods, conventionally, a technique for detecting the amount of salt adhering to the surface of an insulating plate formed with electrodes based on the resistance value between the electrodes in the insulating plate is known. However, the resistance between the electrodes is not determined only by the amount of contamination, but is affected by the ambient relative humidity. Since the behavior of the resistance has hysteresis with respect to the increase and decrease of the relative humidity, an error occurs when converting the degree of contamination based on the relative humidity at the time of measuring the resistance.

[0004] Therefore, in Patent Document 1 described below, the applicant proposed a technique for estimating the amount of contamination of an insulator such as an insulator based on the surface resistivity of an electrode substrate provided with a pair of electrodes and the ambient relative humidity, and estimating the amount of contamination (equivalent salt adhesion amount) from the relationship between the maximum value of the relative humidity for a certain period and the surface resistivity. Thereby, it becomes possible to accurately estimate the amount of contamination even when the behavior of the resistance has hysteresis with respect to the change in relative humidity.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The technology of Patent Document 1 is suitable for detecting rapid fouling in an outdoor environment. On the other hand, fouling of insulators can occur not only in the outdoor environment but also inside electrical equipment such as switchgear. Therefore, it is necessary to detect the degree of fouling of the insulators inside the electrical equipment as well.

[0007] Inside electrical equipment, the fouling of insulators progresses gradually compared to the outdoor environment. In addition, since the inside of the electrical equipment is not washed by rain, the fouling is not canceled unless the fouling on the surface of the insulator is forcibly cleaned. When using the technology of Patent Document 1 to detect the degree of fouling of the insulator installed in such an environment, there may be variations in the measured surface resistivity value, so there is a concern that the estimation accuracy of the fouling amount may decrease. Therefore, the technology of Patent Document 1 has room for improvement depending on the installation environment of the insulator.

[0008] The present invention has been made to solve the above problems, and one object of the present invention is to provide a fouling detection device capable of accurately estimating the degree of fouling of an insulator installed inside electrical equipment or the like.

Means for Solving the Problems

[0009] A contamination detection device according to an aspect of the present invention includes an electrode substrate having a pair of electrodes formed on an insulating substrate, a humidity sensor provided on the electrode substrate for measuring humidity, a recording means for recording the electrode resistance value between the pair of electrodes and the humidity measured by the humidity sensor at predetermined time intervals, an extraction means for extracting, from the data of the electrode resistance value and humidity recorded by the recording means, the highest humidity value corresponding to an electrode resistance value equal to or less than a preset threshold value within a time range from a certain time ago to the current time as the highest humidity value of humidity movement, an average calculation means for taking out n highest humidity values of humidity movement in ascending order of low humidity among the plurality of highest humidity values of humidity movement extracted by the extraction means and calculating their average value, and a contamination amount estimation means for estimating the contamination amount based on the average value calculated by the average calculation means and the pre-stored contamination amount estimation information.

[0010] The recording means records the electrode resistance value between the pair of electrodes and the humidity measured by the humidity sensor at predetermined time intervals. The extraction means extracts, from the data of the electrode resistance value and humidity recorded by the recording means, the highest humidity value corresponding to an electrode resistance value equal to or less than a preset threshold value within a time range from a certain time ago to the current time as the highest humidity value of humidity movement. The average calculation means takes out n highest humidity values of humidity movement in ascending order of low humidity among the plurality of highest humidity values of humidity movement extracted by the extraction means and calculates their average value. The contamination amount estimation means estimates the contamination amount based on the average value calculated by the average calculation means and the pre-stored contamination amount estimation information. Thus, by estimating the contamination amount using the average value of the highest humidity values of humidity movement on the low humidity side, even when there is variation in the electrode resistance value, the contamination amount of the insulator can be accurately estimated. Further, by providing the humidity sensor on the electrode substrate, the temperature difference due to the installation locations of the electrode substrate and the humidity sensor can be reduced. Thereby, the measurement error of humidity due to the temperature difference can be reduced, so that the contamination amount of the insulator can be estimated more accurately. Therefore, even for an insulator installed inside electrical equipment or the like, the degree of contamination of the insulator can be accurately estimated.

[0011] Preferably, when the average value is AVHM(1~n), the fouling amount estimation means substitutes AVHM(1~n) into the following formula (1) in which the fouling amount of the surface of the electrode substrate is stored as fouling amount estimation information, and obtains S (mg / cm 2 ) and estimates it.

Number

[0012] With this configuration, the fouling amount of the insulator installed inside the electrical equipment etc. can be estimated more accurately.

[0013] More preferably, the fouling detection device further includes a specifying means for specifying, from the humidity data recorded by the recording means in descending order of high humidity, the humidity value Hmax(K×n) at the number n×K from the top, and a sensitivity estimation means for estimating the detection sensitivity of the fouling amount based on the humidity value Hmax(K×n) specified by the specifying means. The sensitivity estimation means substitutes the humidity value Hmax(K×n) into the following formula (2) stored in advance to obtain S'(mg / cm 2 ) and estimates it.

Number

[0014] Thereby, the detection sensitivity of the fouling amount can be estimated. Therefore, when the electrode resistance value has not decreased below the threshold value, that is, when fouling is not detected, based on the estimated detection sensitivity, it can be determined whether the cause is that the insulator is not actually fouled, or that the detection sensitivity has decreased due to low humidity although it is fouled.

[0015] More preferably, a pair of electrodes are arranged on the surface of the electrode substrate, and the humidity sensor is arranged on the surface of the electrode substrate opposite to the surface on which the electrodes are formed. By installing the humidity sensor on the surface (back surface) of the electrode substrate opposite to the surface on which the electrodes are formed, the temperature difference from the electrode substrate can be made smaller, the humidity on the electrode substrate can be accurately measured, and the influence of dust on the humidity sensor can also be minimized. Since the measurement accuracy of humidity by the humidity sensor can be improved, the estimation accuracy of the contamination amount of the insulator can be further improved.

[0016] More preferably, the electrode interval on the electrode substrate is 0.5 mm or more and 2.0 mm or less, and the electrode width on the electrode substrate is 10 times or more and 40 times or less the electrode interval. Thereby, the decrease in sensitivity of the electrode resistance decrease can be suppressed with a voltage that can be easily output by the electronic circuit. That is, the sensitivity of the resistance decrease can be ensured.

[0017] Note that the technology disclosed in the present application can be realized not only as a contamination detection device including such a characteristic configuration. It can also be realized as a program for causing a computer to execute the characteristic steps executed by the contamination detection device, and a recording medium on which the program is recorded. Further, it can be realized as a semiconductor integrated circuit that realizes part or all of the contamination detection device. Furthermore, it can be realized as other systems including the contamination detection device.

Effects of the Invention

[0018] As described above, according to the present invention, it is possible to provide a contamination detection device capable of accurately estimating the degree of contamination of an insulator installed inside electrical equipment or the like.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same parts or components are given the same reference numerals and names. Their functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0021] (First Embodiment) The stain detection device according to the present embodiment mainly measures salt (sodium chloride). This stain detection device is installed in the same environment as the insulator to be measured, and estimates the salt adhesion amount attached to the surface of the insulator as the stain amount. Assume that the insulator to be measured is installed in a switchgear which is an electrical equipment.

[0022] Referring to FIG. 1, the switchgear 10 is a device for receiving power at a voltage determined for safe power supply, transforming it into a user-friendly voltage, and distributing it to each load. It is housed in a metal-enclosed case so that it can be used safely for a long time, and is equipped with a switch for operating the equipment, a meter for measuring voltage, current, etc., and a protection relay for detecting abnormalities. Inside the switchgear 10, an insulator (insulating material: not shown) for insulating electricity is installed.

[0023] [Overall Configuration] Referring to FIG. 2, the contamination detection device 50 according to the present embodiment includes a sensor unit 100 and a control device 200. At least the sensor unit 100 of the contamination detection device 50 is installed in the same environment as the insulating material to be measured, that is, inside the switchgear 10. The control device 200 may be installed inside the switchgear 10 together with the sensor unit 100, or may be installed outside the switchgear 10.

[0024] The sensor unit 100 includes an electrode substrate 110 having a pair of electrode patterns formed on the surface of an insulating substrate 112, and a humidity sensor 120 for measuring the ambient relative humidity. The humidity sensor 120 is installed on the electrode substrate 110. The sensor unit 100 is communicably connected to the control device 200 by wire or wirelessly. In the present embodiment, the sensor unit 100 is wired to the control device 200. Details of the sensor unit 100 will be described later.

[0025] The control device 200 includes an analog input circuit 210, a CPU (Central Processing Unit) 220, a memory 230, a communication device 240, and an auxiliary relay 250. The analog input circuit 210 is connected to the electrodes formed on the electrode substrate 110. The analog input circuit 210 applies a predetermined voltage (for example, about 5V) between the pair of electrodes to measure the insulation rate (resistance value between the electrodes) of the electrode substrate 110. The analog input circuit 210 further performs analog / digital conversion on the measured value and supplies it to the CPU 220 as a digital signal of the electrode resistance value.

[0026] The CPU 220 is connected to a humidity sensor 120, an analog input circuit 210, a memory 230, a communication device 240, and an auxiliary relay 250, and controls the entire contamination detection device 50 by controlling these components. The CPU 220 executes a process of estimating the salt adhesion amount (contamination amount) based on the data signals supplied from the humidity sensor 120 and the analog input circuit 210.

[0027] The memory 230 includes a storage device that stores programs and data for the CPU 220 to control the contamination detection device 50. In the memory 230, contamination amount estimation information used during the process of estimating the salt adhesion amount (contamination amount) is stored in advance. The memory 230 further includes a data recording device that records data such as the relative humidity acquired via the humidity sensor 120, the electrode resistance value of the electrode substrate 110 acquired via the analog input circuit 210, and the salt adhesion observation result (salt adhesion amount) estimated by the CPU 220 from these data.

[0028] The communication device 240 communicates with a host device either wired or wirelessly. The host device includes, for example, a monitoring device installed in a central monitoring room or the like. In this case, it is preferable that the control device 200 is configured to transmit the data recorded in the data recording device to the host device (monitoring device) via the communication device 240. Thereby, the contamination level of the insulator installed inside the switchgear 10 can be monitored.

[0029] The auxiliary relay 250 is a mechanical relay or a semiconductor relay and functions as a contact for contact output. The auxiliary relay 250 is turned ON / OFF under the control of the CPU 220, and outputs an alarm, for example, by sounding a buzzer or lighting a lamp connected thereto when the salt adhesion observation result is equal to or greater than a predetermined value, or when an abnormality is detected.

[0030] [Configuration of Sensor Unit 100] Referring to FIG. 3, the sensor unit 100 includes the electrode substrate 110 and the humidity sensor 120 as described above. Referring to FIG. 3(A), the electrode substrate 110 includes an insulating substrate 112 made of glass epoxy, ceramic, or the like, and a pair of electrodes 114 formed on the surface of the insulating substrate 112. The pair of electrodes 114 is composed of a conductor such as metal and is formed in a predetermined electrode pattern on the surface of the insulating substrate 112. In the present embodiment, for the purpose of achieving a compact configuration, the electrode pattern (electrode shape) is a comb-shaped electrode shape. However, the electrode shape of the pair of electrodes is not limited to the comb shape and may be other shapes such as concentric circles. The electrode substrate 110 is preferably subjected to a treatment such as gold plating for the purpose of preventing corrosion of the electrodes 114.

[0031] The distance (electrode interval) D between the pair of electrodes 114 is preferably 0.5 mm or more and 2 mm or less for the purpose of ensuring the sensitivity of resistance reduction with a voltage (about 5 V) that can be easily output by an electronic circuit. In the present embodiment, the electrode interval D is, for example, 0.9 mm. The electrode width L is preferably 10 times or more the electrode interval D. The upper limit value is arbitrary. When an upper limit value is provided, the electrode width L is preferably 40 times or less the electrode interval D. In the case of the electrode pattern shown in FIG. 3(A), the electrode width L can be 35 times (31.5 mm) the electrode interval D.

[0032] The electrode substrate 110 is preferably installed such that the electrode formation surface faces upward (upper surface) so as to be affected by dust deposition on the side where the pair of electrodes 114 is formed (electrode formation surface).

[0033] The humidity sensor 120 is installed on the surface (back surface) of the electrode substrate 110 opposite to the surface on which the electrodes 114 are formed. It is preferable to use a surface-mounted sensor with high humidity measurement accuracy for the humidity sensor 120. For example, for the humidity sensor 120, it is preferable to use a sensor such as the Sensirion SHT-31 that has high humidity measurement accuracy and can be mounted on the substrate surface (the temperature difference between the electrode substrate 110 and the humidity sensor 120 can be minimized). This makes it easy to mount the humidity sensor 120 on the back surface of the electrode substrate 110. In this way, by installing the humidity sensor 120 on the back surface of the electrode substrate 110, the temperature difference between the humidity sensor 120 and the electrode substrate 110 can be minimized, and the influence of dust on the humidity sensor 120 can be minimized.

[0034] The humidity sensor 120 incorporates a humidity measurement circuit that converts humidity measurement data into a digital signal. Therefore, the humidity sensor 120 outputs the humidity measurement data as a digital signal to the CPU 220. However, the humidity sensor 120 may be a type of sensor that does not incorporate a humidity measurement circuit.

[0035] [Method for estimating salt adhesion amount] Subsequently, the estimation process of the salt adhesion amount executed in the contamination detection device 50 according to the present embodiment will be described.

[0036] Referring to FIG. 2 again, the contamination detection device 50 records the electrode resistance value between the pair of electrodes 114 and the relative humidity measured by the humidity sensor 120 at predetermined time intervals (for example, at one-hour intervals). Specifically, the contamination detection device 50 records the electrode resistance value of the electrode substrate 110 and the relative humidity measured by the humidity sensor 120 in the memory 230, for example, once per hour. The contamination detection device 50 records the trend data of the relative humidity and the electrode resistance value for a predetermined measurement period.

[0037] The contamination detection device 50 extracts, as the humidity moving maximum value HMm, the highest value of the humidity corresponding to the electrode resistance value equal to or lower than a preset threshold value within the time range from a certain time ago to the current time from the data of the electrode resistance value and humidity recorded in the memory 230, and records it in another area of the memory 230. Specifically, from the data of the electrode resistance value and humidity recorded between, for example, 48 hours before the current time and the current time, the humidity data corresponding to the electrode resistance value equal to or lower than the threshold value is extracted, and the highest humidity data among them is recorded as the humidity moving maximum value HMm. Such processing is repeated, for example, every hour. When the measurement upper limit value of the electrode resistance is 1000 kΩ, the above threshold value can be set to, for example, 900 kΩ.

[0038] Next, the contamination detection device 50 sorts n pieces of the humidity moving maximum values HMm recorded in the memory 230 in ascending order of low humidity, and calculates the average value AVHM(1~n) of the n humidity moving maximum values HMm. In this embodiment, n is set to 10, for example.

[0039] The following mathematical formula shown in Equation (3) is stored in the memory 230 as the contamination amount estimation information.

Equation

[0040] The constant A and B are different values depending on the threshold value of the electrode resistance, the electrode shape, etc., and are calculated in advance by experiments or the like, and the values are set. In this embodiment, for example, the constant A is 1.02 and the constant B is 0.032. Therefore, in this embodiment, the following mathematical formula shown in Equation (4) is actually stored as the contamination amount estimation information.

Equation

[0041] The contamination detection device 50 estimates the salt adhesion amount attached to the insulator to be measured as S (mg / cm 2 ) obtained by substituting the average value AVHM(1~n) into the contamination amount estimation information.

[0042] Summarizing the above, the contamination detection device 50 estimates the salt adhesion amount by the following process. (A) Record the electrode resistance value and humidity at regular intervals (for example, once per hour). (B) Record the maximum humidity value HMm during the movement (the maximum humidity value from a certain period (for example, 48 hours) before the current value to the current value) when the electrode resistance value becomes equal to or less than a predetermined threshold value. (C) Sort n of the maximum humidity values HMm in ascending order of humidity, and calculate the average value AVHM(1~n). (D) Estimate the salt adhesion amount S (mg / cm 2 ) using the above formula (3) (formula (4)). Specifically, substitute the average value AVHM(1~n) into formula (4) to obtain the salt adhesion amount S (mg / cm 2 ).

[0043] Note that the maximum humidity value HMm during the movement of humidity is used instead of the instantaneous value for the relative humidity because, after the electrode resistance value decreases, the increase in the electrode resistance value lags behind the decrease in humidity over time. Therefore, by using the maximum humidity value HMm during the movement of humidity, the influence of variations in the electrode resistance value is reduced. The time interval (certain period) for obtaining the maximum humidity value HMm during the movement of humidity is preferably 24 hours or more and 72 hours or less. In this embodiment, it is set to 48 hours as described above.

[0044] In the above estimation method, if the electrode resistance value does not drop below the threshold value during the measurement period, the salt adhesion amount is not detected. In this case, the following two cases are conceivable. However, in either case, it can be confirmed that the surface insulation of the insulator in the electrical equipment is maintained. 1) Almost no salt adheres to the electrode. 2) Salt adheres to the electrode, but since the relative humidity has not increased, it has not been detected.

[0045] Here, in order to estimate the salt adhesion amount using the above formula (3), it is necessary that the humidity at which the maximum humidity transfer HMm occurs is generated with a certain frequency. Further, in order to calculate the above average value AVHM(1 to n) by averaging, the humidity at which the maximum humidity transfer HMm occurs needs to be generated with a frequency about 3 to 5 times the number n (10 in this embodiment).

[0046] Taking these points into consideration, it is possible to estimate the detection sensitivity of the salt adhesion amount from the humidity trend during the measurement period. And from the detection sensitivity of the salt adhesion amount, when the salt adhesion amount is not detected, it is possible to determine whether the cause is due to the above 1) or the above 2). For example, when the detection sensitivity of the salt adhesion amount is high (substantially the same as the actual detection sensitivity), it can be determined that "almost no salt adheres to the electrode" in the above 1). On the other hand, when the detection sensitivity of the salt adhesion amount is low (compared to the actual detection sensitivity), it can be determined that "salt adheres to the electrode, but the relative humidity has not increased, so it cannot be detected" in the above 2).

[0047] The detection sensitivity of the salt adhesion amount is calculated by the following process.

[0048] The fouling detection device 50 sorts the humidity data during the measurement period in descending order of humidity, and identifies the humidity value Hmax(K×n) at the K-fold (K is a natural number) number from the top among the n humidity values. The fouling detection device 50 estimates the detection sensitivity of the fouling amount based on the identified humidity value Hmax(K×n).

[0049] In the memory 230, as detection sensitivity estimation information, a mathematical formula shown in the following formula (5) is stored.

Number

[0050] In this embodiment, as described above, the constant A is 1.02 and the constant B is 0.032. Therefore, in this embodiment, as detection sensitivity estimation information, actually, a mathematical formula shown in the following formula (6) is stored.

Number

[0051] The fouling detection device 50 estimates the detection sensitivity S'(mg / cm 2 ) of the salt adhesion amount by substituting the specified humidity value Hmax(K×n) into the detection sensitivity estimation information.

[0052] Summarizing the above, the fouling detection device 50 estimates the detection sensitivity of the salt adhesion amount by the following process. (a) Sort the humidity measurement values during the measurement period in descending order of humidity. (b) Check the humidity value Hmax(K×n) at the K×n-th position from the top after sorting. This indicates that humidity values equal to or higher than this humidity value have occurred K×n times (including the confirmed humidity value). (c) Estimate the detection sensitivity S’(mg / cm 2 ) of the salt adhesion amount in the humidity trend by the above formula (5) (formula (6)). Specifically, the detection sensitivity S’(mg / cm 2 ) of the salt adhesion amount is obtained by substituting the humidity value Hmax(K×n) into formula (6).

[0053] In this embodiment, for example, if n = 10 and K = 4, the approximate detection sensitivity can be estimated. Therefore, based on the estimated detection sensitivity, it is possible to determine whether salt is actually not adhered, or whether salt is adhered but the detection sensitivity has decreased due to low humidity.

[0054] [Verification] For the purpose of confirming the correlation between the salt adhesion amount and humidity, an electrode substrate with salt adhered thereto in a simulated state was installed on an outdoor switchgear, and a test was conducted over a period of about one year. The electrode substrate used in the test has the same configuration as the above-described electrode substrate 110. The salt adhesion amount on the electrode surface is 0.017mg / cm 2 , 0.035mg / cm 2 , 0.063mg / cm 2 , 0.072mg / cm 2 , 0.110mg / cm 2There were five types. That is, five types of electrode substrates with different amounts of salt adhesion on the electrode surface were prepared and installed in an outdoor switchgear. The inside of the switchgear is not a salt-damaged environment, and there is virtually no progress in salt adhesion after the installation of the equipment (electrode substrate). In the test, for each electrode substrate, the electrode resistance value and humidity of the electrode substrate were recorded at regular time intervals (for example, once an hour).

[0055] Figure 4 shows, as an example, the trend data of relative humidity and electrode resistance when the salt adhesion amount was 0.035 mg / cm 2 . Figure 4(A) shows a measurement example of relative humidity, and Figure 4(B) shows a measurement example of electrode resistance. The measurement period was about 13 months from February 2020 to March 2021. From Figure 4, a decrease in electrode resistance (the part enclosed by the dashed line in Figure 4(B)) can be confirmed when the relative humidity increases (the part enclosed by the dashed line in Figure 4(A)).

[0056] Furthermore, while recording the electrode resistance value and humidity, the relative humidity moving maximum value (the humidity maximum value from 48 hours ago to the present) and the corresponding electrode resistance value were extracted from the recorded data and recorded separately. Note that the extraction of these data can be performed even after all the data of the electrode resistance value and humidity have been recorded in the verification test.

[0057] Figure 5 shows a graph plotting the data of the relationship between the relative humidity moving maximum value (the humidity maximum value from 48 hours ago to the present) and the measured electrode resistance value. In each graph of Figure 5, the horizontal axis is the relative humidity moving maximum value (relative humidity 48-hour maximum value (%RH)), and the vertical axis is the measured electrode resistance value (electrode resistance (kΩ), measurement upper limit value: 1000 kΩ). From Figure 5, it was experimentally confirmed that as the salt adhesion amount increases, the relative humidity moving maximum value at which the electrode resistance begins to decrease from the measurement upper limit value decreases.

[0058] Subsequently, for the measured values of each salt adhesion amount, ten relative humidity moving maximum values when the resistance measured value became less than or equal to the threshold value (900 kΩ) were extracted in ascending order and arranged in the order from 1st to 10th. Then, for each measured value of the salt adhesion amount, the average value AVHM(1~10) of the ten relative humidity moving maximum values was calculated. The results are shown in Figure 6.

[0059] Note that the threshold value of the resistance measurement value is indicated by a two-dot chain line in each graph of FIG. 5. The downward arrow near the two-dot chain line indicates the region where the resistance measurement value is below the threshold value. The ten relative humidity moving maximum values are included in the portion surrounded by the broken line on the low humidity side in each graph of FIG. 5.

[0060] As shown in FIG. 6, as the salt adhesion amount increases, the average value AVHM(1 to 10) decreases. FIG. 7 shows a graph of these relationships. In the graph of FIG. 7, the average value AVHM(1 to 10) is plotted on the horizontal axis and each salt adhesion amount is plotted on the vertical axis (logarithmic display).

[0061] As shown in FIG. 7, it was experimentally confirmed that each salt adhesion amount and the average value AVHM(1 to 10) can be approximately linearly approximated logarithmically. In FIG. 7, an approximate straight line P obtained by linearly approximating each plot is shown. When the salt adhesion amount is S, this approximate straight line P of this embodiment is represented by the following formula (7). [Equation]

[0062] The constant A and the constant B in the above formula (4) use the values of formula (7).

[0063] From the above, it was confirmed that if the constant A and the constant B are obtained in advance, the salt adhesion amount can be accurately estimated by the above formula (3) by obtaining the average value AVHM(1 to 10).

[0064] [Effects of this Embodiment] As is clear from the above description, by using the fouling detection device 50 according to this embodiment, the following effects can be obtained.

[0065] The contamination detection device 50 records the electrode resistance value between a pair of electrodes and the humidity measured by the humidity sensor 120 at predetermined time intervals. The control device 200 of the contamination detection device 50 extracts, from the recorded electrode resistance value and humidity data, the highest humidity value corresponding to the electrode resistance value below a preset threshold within the time range from a certain time ago to the current time as the humidity moving maximum value HMm. Among the extracted multiple humidity moving maximum values HMm, n (n is a natural number) humidity moving maximum values HMm are taken out in ascending order of low humidity, and their average value AVHM(1 - 10) is calculated. The control device 200 further estimates the contamination amount based on the calculated average value AVHM(1 - 10) and the contamination amount estimation information stored in advance.

[0066] In this way, the contamination detection device 50 estimates the contamination amount (salt adhesion amount) using the average value AVHM(1 - 10) of the humidity moving maximum values HMm on the low humidity side. Thus, even when there is variation in the electrode resistance value, the contamination amount of the insulator can be accurately estimated. Further, in the contamination detection device 50, the humidity sensor 120 is provided on the electrode substrate 110. Thereby, the temperature difference due to the installation locations of the electrode substrate 110 and the humidity sensor 120 can be reduced, and the measurement error of humidity caused by the temperature difference can be reduced. Therefore, the contamination amount of the insulator can be estimated more accurately, and the contamination degree of the insulator installed inside electrical equipment such as a switch gear can also be accurately estimated.

[0067] By using the information shown in the above formula (3) (formula (4)) as the contamination amount estimation information, the contamination amount on the surface of the electrode substrate 110 can be estimated more accurately based on the calculated average value AVHM(1 - 10). Thereby, the contamination amount of the insulator installed inside electrical equipment and the like can be estimated more accurately.

[0068] Furthermore, by installing the humidity sensor 120 on the surface (back surface) of the electrode substrate 110 opposite to the surface on which the electrode 114 is formed, the temperature difference from the electrode substrate 110 can be made smaller, the humidity on the electrode substrate 110 can be accurately measured, and the influence of dust on the humidity sensor 120 can also be minimized. As a result, the measurement accuracy of humidity by the humidity sensor 120 can be improved, and the estimation accuracy of the contamination amount of the insulator can be further improved.

[0069] Furthermore, by setting the electrode interval D in the electrode substrate 110 to be 0.5 mm or more and 2.0 mm or less, and setting the electrode width L in the electrode substrate 110 to be 10 times or more and 40 times or less the electrode interval D, it is possible to suppress the decrease in sensitivity of the electrode resistance reduction with a voltage that can be easily output by the electronic circuit. That is, the sensitivity of the resistance reduction can be ensured.

[0070] The contamination detection device 50 further sorts the humidity data recorded by the control device 200 in descending order of humidity, specifies the humidity value Hmax(K×n) at the K-fold (K is a natural number) and n-th position from the top, and estimates the detection sensitivity of the contamination amount based on the specified humidity value Hmax(K×n). At this time, the control device 200 substitutes the humidity value Hmax(K×n) into the above-mentioned formula (5) (formula (6)) stored in advance to obtain S'(mg / cm 2 ) and estimates it.

[0071] When the electrode resistance value has not decreased below the threshold value, that is, when no contamination is detected, based on the estimated detection sensitivity, it can be determined whether the cause is that the insulator is actually not contaminated, or that although it is contaminated, the detection sensitivity has decreased due to low humidity.

[0072] (Second Embodiment) In the above-described first embodiment, an example in which the calculation and salt adhesion amount estimation is executed by the CPU 220 (see FIG. 2) of the control device 200 has been shown. However, the present disclosure is not limited to such a configuration. For example, the calculation and salt adhesion amount estimation may be performed by a processing device different from the CPU of the control device. In the present embodiment, a contamination detection device having such a configuration will be described. That is, the contamination detection device according to the present embodiment includes, in addition to the control device, a processing device that performs calculation and salt adhesion amount estimation. In this regard, the contamination detection device according to the present embodiment is different from the first embodiment.

[0073] Referring to FIG. 8, the contamination detection device 50A according to the present embodiment includes a sensor unit 100, a control device 200A, and a processing device 300. The sensor unit 100A has the same configuration as the sensor unit 100 (see FIG. 2) of the first embodiment. That is, the sensor unit 100A includes an electrode substrate 110 in which a pair of electrode patterns are formed on the surface of an insulating substrate 112, and a humidity sensor 120 is installed on the back surface thereof.

[0074] The control device 200A has the same configuration as the control device 200 (see FIG. 2) of the first embodiment. However, in the present embodiment, unlike the first embodiment, the control device 200A does not perform the process of calculating and estimating the salt adhesion amount. The control device 200A records the electrode resistance value between the pair of electrodes 114 and the relative humidity measured by the humidity sensor 120 at predetermined time intervals (for example, at one-hour intervals), and transmits the data (logging data) to the processing device 300.

[0075] The processing device 300 includes a CPU 310, a memory 320, and a communication device 330. The communication device 330 communicates with the control device 200A by wire or wirelessly. The communication device 330 receives the logging data transmitted from the control device 200A and records it in the memory 320. The CPU 310 controls the entire processing device 300. The CPU 310 executes an estimation process of the salt adhesion amount including arithmetic processing on the logging data transmitted from the control device 200A. The memory 320 includes a storage device that stores programs and data for the CPU 310 to control the processing device 300. In the memory 320, the fouling amount estimation information used at the time of estimating the salt adhesion amount (fouling amount) is stored in advance. The CPU 310 reads and executes the programs stored in the memory 320 to execute the arithmetic processing for estimating the salt adhesion amount (fouling amount) and the salt adhesion amount estimation process.

[0076] Thus, in the present embodiment, the process of calculating and estimating the salt adhesion amount executed by the CPU of the control device in the first embodiment is executed by the processing device 300. Thereby, the arithmetic burden on the CPU 310 in the control device 200A can be reduced, and the device can be provided at low cost.

[0077] Note that the processing device 300 may be a general-purpose computer or the like. In this case, by installing a separately provided computer program in a general-purpose computer or the like, the general-purpose computer or the like functions as the processing device 300 that executes the process of calculating and estimating the salt adhesion amount.

[0078] (Modification example) In the above embodiment, an example of estimating the fouling amount of an insulator installed inside a switchgear, which is an example of electrical equipment, has been shown. However, the present invention is not limited to such an embodiment. The insulator to be measured may be installed in electrical equipment other than the switchgear, or may be installed in a place other than electrical equipment.

[0079] In the above embodiment, an example of estimating the amount of fouling (salt adhesion amount) by the calculation using Expression (3) (Expression (4)) has been shown, but the present invention is not limited to such an embodiment. For example, a table showing the amount of fouling with respect to the average value AVHM(1 to n) may be stored as fouling amount estimation information, and the amount of fouling may be estimated by referring to this table. Similarly, instead of estimating the detection sensitivity of the amount of fouling (salt adhesion amount) using Expression (5) (Expression (6)), for example, a table showing the salt adhesion amount detection sensitivity with respect to the humidity value Hmax(K × n) may be stored as detection sensitivity estimation information, and the detection sensitivity of the amount of fouling may be estimated by referring to this table. Further, the characters of the variables in the above Expressions (1) to (7) may be appropriately changed.

[0080] In the above embodiment, an example in which n = 10 and K = 4 has been shown, but the present invention is not limited to such an embodiment. The values of n and K can be appropriately changed.

[0081] The embodiments disclosed this time are merely illustrative, and the present invention is not limited to only the above-described embodiments. The scope of the present invention is shown by each claim in the claims, taking into consideration the description in the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the language described therein.

Explanation of Reference Numerals

[0082] 10 Switch gear 50, 50A Fouling detection device 100, 100A Sensor unit 110 Electrode substrate 112 Insulating substrate 114 Electrode 120 Humidity sensor 200, 200A Control device 210 Analog input circuit 220, 310 CPU 230, 320 Memory 240, 330 Communication device 250 Auxiliary relay 300 Processing device

Claims

1. An electrode substrate having a pair of electrodes formed on an insulating substrate, a humidity sensor provided on the electrode substrate for measuring humidity, recording means for recording the electrode resistance value between the pair of electrodes and the humidity measured by the humidity sensor at predetermined time intervals respectively, extracting means for extracting, from the data of the electrode resistance value and humidity recorded by the recording means, the highest humidity value corresponding to an electrode resistance value equal to or lower than a preset threshold value within a time range from a certain time before to the current time as the highest humidity movement value, average calculation means for taking out n highest humidity movement values in ascending order of low humidity among the plurality of highest humidity movement values extracted by the extracting means and calculating their average value, A fouling detection device including fouling amount estimation means for estimating a fouling amount based on the average value calculated by the average calculation means and pre-stored fouling amount estimation information.

2. When the average value is AVHM(1 to n), The fouling amount estimation means estimates the fouling amount on the surface of the electrode substrate as S (mg / cm obtained by substituting the AVHM (1 to n) into the following formula (1) stored as the fouling amount estimation information ２ ). 【Number 1】 The fouling detection device according to Claim 1.

3. specifying means for specifying, from the humidity data recorded by the recording means, the humidity value Hmax(K×n) at the (K times (K is a natural number) of the n)th position from the top in descending order of high humidity, further including sensitivity estimation means for estimating the detection sensitivity of the fouling amount based on the humidity value Hmax(K×n) specified by the specifying means, The sensitivity estimation means estimates the detection sensitivity of the contamination amount as S' (mg / cm obtained by substituting the humidity value Hmax (K × n) into the following formula (2) stored in advance. ２ ) 【Number 2】 The fouling detection device according to Claim 2.

4. The pair of electrodes are arranged on the surface of the electrode substrate, The humidity sensor is arranged on the surface of the electrode substrate opposite to the surface on which the electrodes are formed. The fouling detection device according to any one of Claims 1 to 3.

5. The electrode interval on the electrode substrate is 0.5 mm or more and 2.0 mm or less, The electrode width on the electrode substrate is 10 times or more and 40 times or less the electrode interval. The fouling detection device according to any one of Claims 1 to 4.

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