JP7709027B2 - Dirt detection device - Google Patents

Description

The present invention relates to a contamination detection device, and in particular to a technology suitable for detecting contamination of insulating materials installed inside electrical equipment, etc.

The insulating properties of insulators and other insulating materials decrease when salt accumulates on their surfaces and becomes contaminated. If the power generation and transformation facilities in which the insulators are installed are located in salt damage areas, there is a particular risk of the insulation properties decreasing because salt easily accumulates. For this reason, it is necessary to constantly monitor the degree of contamination of insulators and other insulating materials and clean them when necessary.

Various methods have been proposed for detecting the degree of contamination of insulators. One such method is a technique that detects the amount of salt attached to the surface of an insulating plate based on the inter-electrode resistance value in an insulating plate on which electrodes are formed. However, the resistance between the electrodes is not determined only by the amount of contamination, but is also affected by the surrounding relative humidity. The behavior of this resistance has hysteresis in response to fluctuations in the relative humidity rising and falling, so an error will occur if the degree of contamination is converted using the relative humidity at the time the resistance is measured.

Therefore, in Patent Document 1, the applicant proposed a technology for estimating the amount of contamination of an insulating material such as an insulator based on the surface resistivity of an electrode substrate on which a pair of electrodes are provided and the surrounding relative humidity, in which the amount of contamination (equivalent amount of salt adhesion) is estimated from the relationship between the maximum value of relative humidity in a certain period and the surface resistivity. This makes it possible to accurately estimate the amount of contamination even when the behavior of the resistance has hysteresis in response to fluctuations in relative humidity.

JP 2018-142470 A

The technology of Patent Document 1 is suitable for detecting rapid contamination in outdoor environments. However, contamination of insulating materials can occur not only in outdoor environments but also inside electrical equipment such as switchgear. Therefore, it is necessary to detect the degree of contamination of insulating materials inside electrical equipment as well.

Inside electrical equipment, contamination of insulators progresses more gradually than in outdoor environments. In addition, inside electrical equipment, contamination is not washed away by rain, so contamination will not be eliminated unless the contamination on the surface of the insulator is forcibly cleaned. When the technology of Patent Document 1 is used to detect the degree of contamination of insulators installed in such an environment, there is a concern that the accuracy of estimating the amount of contamination will decrease because variations in the measured surface resistivity may occur. Therefore, the technology of Patent Document 1 has room for improvement depending on the installation environment of the insulator.

The present invention has been made to solve the above problems, and one object of the present invention is to provide a contamination detection device that can accurately estimate the degree of contamination of insulating materials installed inside electrical equipment, etc.

The contamination detection device according to one 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, respectively, an extraction means for extracting, from the electrode resistance value and humidity data recorded by the recording means, the maximum 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 present time as a maximum humidity movement value, an averaging means for taking n maximum humidity movement values in order of decreasing humidity from the multiple maximum humidity movement values extracted by the extraction means and calculating their average value, and a contamination amount estimation means for estimating the amount of contamination based on the average value calculated by the average calculation means and pre-stored contamination amount estimation information.

The recording means records the electrode resistance between the pair of electrodes and the humidity measured by the humidity sensor at a predetermined time interval. The extraction means extracts the maximum humidity value corresponding to the electrode resistance value equal to or less than a preset threshold value in a time range from a certain time ago to the present time from the electrode resistance value and humidity data recorded by the recording means as the maximum humidity movement value. The average calculation means extracts n maximum humidity movement values in order of low humidity from the multiple maximum humidity movement values 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 contamination amount estimation information stored in advance. In this way, by estimating the contamination amount using the average value of the maximum humidity movement value on the low humidity side, the contamination amount of the insulator can be accurately estimated even if the electrode resistance value varies. Furthermore, by providing the humidity sensor on the electrode substrate, the temperature difference due to the installation location of the electrode substrate and the humidity sensor can be reduced. This reduces the humidity measurement error caused by the temperature difference, so that the contamination amount of the insulator can be more accurately estimated. Therefore, the degree of contamination of insulating materials installed inside electrical equipment, etc. can be accurately estimated.

Preferably, when the average value is AVHM (1 to n), the contamination amount estimation means estimates the amount of contamination on the surface of the electrode substrate as S (mg/ ^cm2 ) obtained by substituting AVHM (1 to n) into the following formula (1) stored as contamination amount estimation information.

This configuration allows for more accurate estimation of the amount of contamination of insulating materials installed inside electrical equipment, etc.

More preferably, the soil detection device further includes an identification means for identifying the humidity value Hmax (K×n) that is the nth K-th (K is a natural number) humidity value recorded by the recording means in order of high humidity, and a sensitivity estimation means for estimating the detection sensitivity of the amount of soiling based on the humidity value Hmax (K×n) identified by the identification means, and the sensitivity estimation means estimates the detection sensitivity of the amount of soiling as S' (mg/ ^cm2 ) obtained by substituting the humidity value Hmax (K×n) into the following formula (2) that is stored in advance.

This allows the detection sensitivity of the amount of contamination to be estimated. Therefore, if the electrode resistance value does not fall below the threshold value, i.e., if contamination is not detected, it is possible to determine based on the estimated detection sensitivity whether this is due to the insulator not actually being contaminated, or whether it is contaminated but the detection sensitivity has been reduced due to low humidity.

More preferably, the pair of electrodes are disposed on the surface of the electrode substrate, and the humidity sensor is disposed on the surface of the electrode substrate opposite to the surface on which the electrodes are formed. By locating the humidity sensor on the surface of the electrode substrate opposite to the surface on which the electrodes are formed (back surface), the temperature difference with the electrode substrate can be further reduced, allowing the humidity on the electrode substrate to be measured accurately, and the effect of dust on the humidity sensor can be minimized. Since the accuracy of the humidity measurement by the humidity sensor can be improved, the accuracy of estimating the amount of contamination of the insulator can be further improved.

More preferably, the electrode spacing 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 spacing. This makes it possible to suppress the decrease in sensitivity due to electrode resistance reduction with a voltage that can be easily output by an electronic circuit. In other words, the sensitivity to resistance reduction can be ensured.

The technology disclosed in this application can be realized not only as a dirt 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 dirt detection device, or a recording medium on which the program is recorded. It can also be realized as a semiconductor integrated circuit that realizes part or all of the dirt detection device. Furthermore, it can also be realized as other systems that include the dirt detection device.

As described above, the present invention provides a contamination detection device that can accurately estimate the degree of contamination of insulating materials installed inside electrical equipment, etc.

FIG. 2 is a perspective view showing the appearance of the switchgear. 1 is a block diagram showing a configuration of a soiling detection device according to a first embodiment. 3A is a plan view showing the configuration of the sensor section (electrode substrate) of the soil detection device shown in FIG. 2, where FIG. 3A is a plan view of the upper surface side on which the electrode pattern is formed, and FIG. 3B is a plan view of the lower surface side on which the humidity sensor is installed. FIG. ² is a graph showing trend data of relative humidity and electrode resistance when the amount of salt adhesion is set to 0.035 mg/cm2, in which the upper part shows an example of relative humidity measurement and the lower part shows an example of electrode resistance measurement. 1 is a graph plotting data on the relationship between the maximum relative humidity movement (maximum humidity value from 48 hours ago to the present) and measured electrode resistance values. FIG. 13 is a diagram showing the results of arranging the maximum relative humidity shift values from lowest to highest, when the measured resistance value became 900 kΩ or less, from number 1 to number 10. This is a graph in which the average value of the maximum relative humidity movement (numbers 1 to 10 in ascending order) is plotted on the horizontal axis, and each amount of salt adhesion is plotted on the vertical axis (logarithmic scale). FIG. 11 is a block diagram showing a configuration of a soiling detection device according to a second embodiment.

The following describes in detail an embodiment of the present invention with reference to the drawings. In the following description and drawings, the same parts or components are given the same reference symbols and names. Their functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

First Embodiment
The contamination detection device according to this embodiment mainly measures salt (sodium chloride). This contamination detection device is installed in the same environment as the insulating material to be measured, and estimates the amount of salt adhering to the surface of the insulating material as the amount of contamination. The insulating material to be measured is assumed to be installed in a switchgear, which is an electrical equipment.

Referring to FIG. 1, the switchgear 10 is a device that receives electricity at a set voltage to safely supply it, transforms it into an easy-to-use voltage, and distributes it to each load. It is housed in a metal enclosure to ensure safe long-term use, and is equipped with switches for operating the equipment, meters for measuring voltage, current, etc., and protective relays for detecting abnormalities. An insulator (not shown) for insulating electricity is installed inside the switchgear 10.

[Overall configuration]
2 , the contamination detection device 50 according to the present embodiment includes a sensor unit 100 and a control device 200. In the contamination detection device 50, at least the sensor unit 100 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.

The sensor unit 100 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 that measures the surrounding relative humidity. The humidity sensor 120 is installed on the electrode substrate 110. The sensor unit 100 is connected to the control device 200 in a wired or wireless manner so as to be able to communicate with the control device 200. In this embodiment, the sensor unit 100 is connected to the control device 200 by wire. Details of the sensor unit 100 will be described later.

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 electrodes formed on the electrode substrate 110. The analog input circuit 210 applies a predetermined voltage (e.g., about 5 V) between a 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 of the measurement value and supplies it to the CPU 220 as an electrode resistance value in a digital signal.

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

The memory 230 includes a storage device that stores programs and data for the CPU 220 to control the contamination detection device 50. The memory 230 prestores contamination amount estimation information used during the process of estimating the amount of salt adhesion (amount of contamination). 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 results (amount of salt adhesion) estimated by the CPU 220 from these data.

The communication device 240 communicates with a higher-level device via wired or wireless communication. The higher-level device includes, for example, a monitoring device installed in a central monitoring room. In this case, it is preferable that the control device 200 is configured to transmit data recorded in the data recording device to the higher-level device (monitoring device) via the communication device 240. This makes it possible to monitor the degree of contamination of the insulator installed inside the switchgear 10.

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 by sounding a buzzer connected to it or lighting a lamp, for example, when the salt adhesion observation result is equal to or exceeds a predetermined value, or when an abnormality is detected.

[Configuration of sensor unit 100]
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 or ceramic, and a pair of electrodes 114 formed on the surface of the insulating substrate 112. The pair of electrodes 114 are made of a conductor such as metal, and are formed in a predetermined electrode pattern on the surface of the insulating substrate 112. In this embodiment, the electrode pattern (electrode shape) is a comb-shaped electrode shape for the purpose of achieving a compact configuration. However, the electrode shape of the pair of electrodes is not limited to the comb shape, and may be other shapes such as a concentric circle shape. It is preferable that the electrode substrate 110 is treated with gold plating or the like for the purpose of preventing corrosion of the electrodes 114.

The distance (electrode spacing) D between a pair of electrodes 114 is preferably 0.5 mm or more and 2 mm or less in order to ensure sensitivity to resistance drop at a voltage (about 5 V) that can be easily output by an electronic circuit. In this embodiment, the electrode spacing D is, for example, 0.9 mm. The electrode width L is preferably 10 times or more the electrode spacing D. The upper limit is arbitrary. If an upper limit is set, the electrode width L is preferably 40 times or less the electrode spacing D. In the case of the electrode pattern shown in FIG. 3(A), the electrode width L can be 35 times the electrode spacing D (31.5 mm).

The electrode substrate 110 is preferably installed so that the surface on which the pair of electrodes 114 are formed (electrode formation surface) is on the upper side (top surface) so that the surface is subject to the effects of dust accumulation.

The humidity sensor 120 is installed on the surface (back side) 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, it is preferable to use a sensor such as Sensirion's SHT-31, which has high humidity measurement accuracy and can be mounted on the substrate surface (minimizing the temperature difference between the electrode substrate 110 and the humidity sensor 120). This makes it easy to mount the humidity sensor 120 on the back side of the electrode substrate 110. In this way, by installing the humidity sensor 120 on the back side of the electrode substrate 110, it is possible to minimize the temperature difference between the humidity sensor 120 and the electrode substrate 110 and to minimize the effect of dust on the humidity sensor 120.

The humidity sensor 120 has a built-in humidity measurement circuit that converts the humidity measurement data into a digital signal. Therefore, the humidity sensor 120 outputs the humidity measurement data to the CPU 220 as a digital signal. However, the humidity sensor 120 may be a type of sensor that does not have a built-in humidity measurement circuit.

[Method for estimating salt deposition amount]
Next, the process of estimating the amount of salt adhesion executed in the contamination detection device 50 according to this embodiment will be described.

Referring again to FIG. 2, the soiling 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 (e.g., one-hour intervals). Specifically, the soiling 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 an hour. The soiling detection device 50 records trend data of the relative humidity and the electrode resistance value for a predetermined measurement period.

The soil detection device 50 extracts the maximum humidity value corresponding to an electrode resistance value below a preset threshold value in a time range from a certain time ago to the present time from the electrode resistance value and humidity data recorded in the memory 230 as the maximum humidity movement value HMm, and records it in a separate area of the memory 230. Specifically, from the electrode resistance value and humidity data recorded between, for example, 48 hours ago and the present time, humidity data corresponding to an electrode resistance value below a threshold value is extracted, and the highest humidity data among them is recorded as the maximum humidity movement value HMm. This process is repeated, for example, every hour. The threshold value can be, for example, 900 kΩ when the upper measurement limit of the electrode resistance is 1000 kΩ.

Next, the soiling detection device 50 sorts the n humidity movement maximum values HMm recorded in the memory 230 in order of decreasing humidity, and calculates the average value AVHM (1 to n) of the n humidity movement maximum values HMm. In this embodiment, n is set to 10, for example.

The memory 230 stores the following equation (3) as the contamination amount estimation information.

The constants A and B are values that differ depending on the electrode resistance threshold value, the electrode shape, etc., and are calculated in advance by experiments, etc., 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 formula shown in the following formula (4) is actually stored as the contamination amount estimation information.

The contamination detection device 50 estimates S (mg/cm ² ) obtained by substituting the average value AVHM (1 to n) into contamination amount estimation information as the amount of salt adhering to the insulating material being measured.

In summary, the contamination detection device 50 estimates the amount of salt adhesion through the following process.
(A) The electrode resistance value and humidity are recorded at regular intervals (for example, once an hour).
(B) The maximum humidity movement value HMm (the maximum humidity value from a certain period (for example, 48 hours) before the current value) when the electrode resistance value becomes equal to or lower than a predetermined threshold value is recorded.
(C) The n humidity movement maximum values HMm are sorted in order of decreasing humidity, and their average values AVHM (1 to n) are calculated.
(D) The amount of salt adhesion S (mg/cm ² ) is estimated by the above formula (3) (formula (4)). Specifically, the amount of salt adhesion S (mg/cm ² ) is obtained by substituting the average value AVHM (1 to n) into formula (4).

The reason why the maximum humidity transfer value HMm is used for the relative humidity instead of the instantaneous value is that after the electrode resistance value decreases, the increase in the electrode resistance value is delayed in relation to the decrease in humidity. Therefore, by using the maximum humidity transfer value HMm, the influence of variations in the electrode resistance value is reduced. The time interval (fixed period) for determining the maximum humidity transfer value HMm is preferably 24 hours or more and 72 hours or less. In this embodiment, it is set to 48 hours as described above.

In the above estimation method, if the electrode resistance value does not fall below the threshold value during the measurement period, the amount of salt adhesion will not be detected. In this case, the following two cases are possible. However, in either case, it can be confirmed that the surface insulation of the insulators in the electrical equipment is maintained.
1) There is (almost) no salt attached to the electrodes.
2) Salt is attached to the electrode, but it cannot be detected because the relative humidity is not increasing.

Here, in order to estimate the amount of salt adhesion using the above formula (3), it is necessary that the humidity that becomes the humidity movement maximum value HMm occurs with a certain frequency. Furthermore, in order to calculate the above average value AVHM (1 to n) by averaging, the humidity that becomes the humidity movement maximum value HMm needs to occur with a frequency of about 3 to 5 times the number n (10 in this embodiment).

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

The detection sensitivity of salt adhesion is calculated using the following process.

The soiling detection device 50 sorts the humidity data from the measurement period in descending order of humidity and identifies the humidity value Hmax (K×n) that is the nth (K is a natural number) multiple of the top humidity value. The soiling detection device 50 estimates the detection sensitivity of the amount of soiling based on the identified humidity value Hmax (K×n).

The memory 230 stores the following formula (5) as detection sensitivity estimation information.

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

The contamination detection device 50 estimates S′ (mg/cm ² ) as the detection sensitivity of the amount of attached salt by substituting the identified humidity value Hmax (K×n) into detection sensitivity estimation information.

In summary, the contamination detection device 50 estimates the detection sensitivity of the amount of salt adhesion through the following process.
(a) Humidity measurements during the measurement period are sorted in descending order of humidity.
(b) The humidity value Hmax(K×n) that is the (K×n)th value from the top of the sorting is confirmed.
This indicates that humidity values equal to or greater than this humidity value have occurred K×n times (including the humidity value just confirmed).
(c) The detection sensitivity S' (mg/ ^cm2 ) of the amount of salt adhesion in the humidity trend is estimated using the above formula (5) (formula (6)). Specifically, the detection sensitivity S' (mg/ ^cm2 ) of the amount of salt adhesion is obtained by substituting the humidity value Hmax (K×n) into formula (6).

In this embodiment, for example, if n = 10 and K = 4, the detection sensitivity can be roughly estimated. Therefore, based on the estimated detection sensitivity, it can be determined whether there is actually no salt attached, or whether there is salt attached but the detection sensitivity has decreased due to low humidity.

[verification]
In order to confirm the correlation between the amount of salt adhesion and humidity, an electrode substrate with simulated salt adhesion on the electrode surface was installed in an outdoor switchgear, and a test was performed for about one year. The electrode substrate used in the test had the same configuration as the electrode substrate 110 described above. The amount of salt adhesion on the electrode surface was set to five types, namely, 0.017 mg/cm ² , 0.035 mg/cm ² , 0.063 mg/cm ² , 0.072 mg/cm ² , and 0.110 mg/cm ² . That is, five types of electrode substrates with different amounts of salt adhesion on the electrode surface were created and installed in the outdoor switchgear. The inside of the switchgear was not a salt damage environment, and salt adhesion did not progress substantially after the equipment (electrode substrate) was installed. In the test, the electrode resistance value and humidity of the electrode substrate were recorded at regular time intervals (for example, once per hour) for each electrode substrate.

As an example, Figure 4 shows trend data of relative humidity and electrode resistance when the amount of salt adhesion is 0.035 mg/ ^cm2 . Figure 4(A) is a measurement example of relative humidity, and Figure 4(B) is a measurement example of electrode resistance. The measurement period is approximately 13 months from February 2020 to March 2021. From Figure 4, it can be confirmed that the electrode resistance decreases (the area surrounded by the dashed line in Figure 4(B)) when the relative humidity increases (the area surrounded by the dashed line in Figure 4(A)).

In addition, while recording the electrode resistance value and humidity, the maximum relative humidity movement value (maximum humidity 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 in the verification test, this data extraction can be performed even after all electrode resistance value and humidity data have been recorded.

Figure 5 shows a graph plotting data on the relationship between the maximum relative humidity movement (maximum humidity from 48 hours ago to the present) and the measured electrode resistance. In each graph in Figure 5, the horizontal axis is the maximum relative humidity movement (maximum relative humidity over 48 hours (% RH)), and the vertical axis is the measured electrode resistance (electrode resistance (kΩ), upper measurement limit: 1000 kΩ). Figure 5 experimentally confirmed that the maximum relative humidity movement, at which the electrode resistance begins to decrease from the upper measurement limit, decreases with an increase in the amount of salt adhesion.

Next, for each salt adhesion measurement, the 10 lowest maximum relative humidity shift values when the resistance measurement value fell below the threshold value (900 kΩ) were extracted and sorted from 1 to 10. Then, for each salt adhesion measurement, the average value AVHM (1 to 10) of the 10 maximum relative humidity shift values was calculated. The results are shown in Figure 6.

The threshold resistance measurement value is indicated by a two-dot chain line in each graph in Figure 5. The downward arrow near the two-dot chain line indicates the area where the resistance measurement value is below the threshold value. The 10 maximum relative humidity movement values are included in the area surrounded by the dashed line on the low humidity side in each graph in Figure 5.

Figure 6 shows that as the amount of salt adhesion increases, the average value AVHM (1-10) decreases. Figure 7 shows a graph of this relationship. The graph in Figure 7 plots the average value AVHM (1-10) on the horizontal axis and each amount of salt adhesion on the vertical axis (logarithmic).

It was experimentally confirmed from Figure 7 that each salt adhesion amount and the average value AVHM (1 to 10) can be logarithmically approximated by a straight line. Figure 7 shows an approximation line P obtained by linearly approximating each plot. When the salt adhesion amount is S, the approximation line P in this embodiment is expressed by the following formula (7).

The constants A and B in the above formula (4) use the values in formula (7).

From the above, it was confirmed that if constants A and B are calculated in advance, the amount of salt adhesion can be accurately estimated using the above formula (3) by calculating the average value AVHM (1 to 10).

[Effects of this embodiment]
As is clear from the above description, by using the soiling detection device 50 according to this embodiment, the following effects are achieved.

The soil detection device 50 records the electrode resistance between a pair of electrodes and the humidity measured by the humidity sensor 120 at predetermined time intervals. The control device 200 of the soil detection device 50 extracts, from the recorded electrode resistance and humidity data, the maximum 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 present time as the maximum humidity movement value HMm, and from the multiple extracted maximum humidity movement values HMm, extracts n (n is a natural number) maximum humidity movement values HMm in order of decreasing humidity and calculates their average value AVHM (1 to 10). The control device 200 further estimates the amount of soiling based on the calculated average value AVHM (1 to 10) and pre-stored soiling amount estimation information.

In this way, the contamination detection device 50 estimates the amount of contamination (amount of salt adhesion) using the average value AVHM (1 to 10) of the maximum humidity movement value HMm on the low humidity side, so that even if there is variation in the electrode resistance value, the contamination amount of the insulator can be accurately estimated. Furthermore, in the contamination detection device 50, the humidity sensor 120 is provided on the electrode substrate 110. This makes it possible to reduce the temperature difference due to the installation location of the electrode substrate 110 and the humidity sensor 120, and therefore reduces the humidity measurement error caused by the temperature difference. Therefore, since the amount of contamination of the insulator can be estimated more accurately, the degree of contamination of the insulator can be accurately estimated even for insulators installed inside switchgear (electrical equipment) etc.

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 more accurately estimated based on the calculated average value AVHM (1 to 10). This makes it possible to more accurately estimate the contamination amount of insulating materials installed inside electrical equipment, etc.

Furthermore, by placing the humidity sensor 120 on the surface (back surface) of the electrode substrate 110 opposite to the surface on which the electrodes 114 are formed, the temperature difference with the electrode substrate 110 can be further reduced, allowing the humidity on the electrode substrate 110 to be accurately measured, and the effect of dust on the humidity sensor 120 can also be minimized. This increases the accuracy of the humidity measurement by the humidity sensor 120, and further increases the accuracy of estimating the amount of contamination of the insulator.

Furthermore, by setting the electrode spacing D in the electrode substrate 110 to 0.5 mm or more and 2.0 mm or less, and setting the electrode width L in the electrode substrate 110 to 10 times or more and 40 times or less the electrode spacing D, it is possible to suppress the decrease in sensitivity due to the electrode resistance decrease at a voltage that can be easily output by an electronic circuit. In other words, it is possible to ensure the sensitivity to the resistance decrease.

The soil detection device 50 further sorts the humidity data recorded by the control device 200 in descending order of humidity, identifies the humidity value Hmax (K×n) that is the nth (K is a natural number) multiple of the top humidity data, and estimates the detection sensitivity of the amount of soiling based on the identified humidity value Hmax (K×n). At this time, the control device 200 estimates the detection sensitivity of the amount of soiling as S' (mg/ ^cm2 ) obtained by substituting the humidity value Hmax (K×n) into the above-mentioned formula (5) (formula (6)) that is stored in advance.

If the electrode resistance value does not fall below the threshold value, i.e., if no contamination is detected, it is possible to determine based on the estimated detection sensitivity whether this is due to the insulator not actually being contaminated, or whether it is contaminated but the detection sensitivity has decreased due to low humidity.

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

Referring to FIG. 8, the soil detection device 50A according to this embodiment includes a sensor unit 100, a control device 200A, and a processing device 300. The sensor unit 100A has a configuration similar to that of the sensor unit 100 of the first embodiment (see FIG. 2). That is, the sensor unit 100A is composed of an electrode substrate 110 having a pair of electrode patterns formed on the surface of an insulating substrate 112, and a humidity sensor 120 is installed on the back surface thereof.

The control device 200A has a configuration similar to that of the control device 200 of the first embodiment (see FIG. 2). However, unlike the first embodiment, in this embodiment, the control device 200A does not perform calculations or salt adhesion estimation processes. 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 (e.g., one-hour intervals), and transmits the data (logging data) to the processing device 300.

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 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 a salt adhesion amount estimation process, including a calculation process, on the logging data transmitted from the control device 200A. The memory 320 includes a storage device that stores a program and data for the CPU 310 to control the processing device 300. The memory 320 stores in advance the contamination amount estimation information used during the estimation process of the salt adhesion amount (contamination amount). The CPU 310 executes the calculation process and the salt adhesion amount estimation process for estimating the salt adhesion amount (contamination amount) by reading and executing the program stored in the memory 320.

In this manner, in this embodiment, the calculation and salt adhesion amount estimation processes that are performed by the CPU of the control device in the first embodiment are performed by the processing device 300. This reduces the calculation burden on the CPU 310 in the control device 200A, making it possible to provide the device at a low cost.

The processing device 300 may be a general-purpose computer or the like. In this case, by installing a separately provided computer program in the general-purpose computer or the like, the general-purpose computer or the like functions as the processing device 300 that performs the calculation and salt adhesion amount estimation process.

(Modification)
In the above embodiment, an example of estimating the amount of contamination of an insulator installed inside a switchgear, which is an example of electrical equipment, has been described, but the present invention is not limited to such an embodiment. The insulator to be measured may be installed in electrical equipment other than a switchgear, or may be installed in a location other than electrical equipment.

In the above embodiment, an example of estimating the amount of contamination (amount of salt adhesion) by calculation using formula (3) (formula (4)) has been shown, but the present invention is not limited to such an embodiment. For example, a table showing the amount of contamination for the average value AVHM (1 to n) may be stored as contamination amount estimation information, and the amount of contamination may be estimated by referring to this table. Similarly, instead of estimating the detection sensitivity of the amount of contamination (amount of salt adhesion) using formula (5) (formula (6)), for example, a table showing the detection sensitivity of the amount of salt adhesion for the humidity value Hmax (K x n) may be stored as detection sensitivity estimation information, and the detection sensitivity of the amount of contamination may be estimated by referring to this table. In addition, the letters of the variables in the above formulas (1) to (7) may be changed as appropriate.

In the above embodiment, an example in which n = 10 and K = 4 is shown, but the present invention is not limited to such an embodiment. The values of n and K can be changed as appropriate.

The embodiments disclosed herein are merely examples, and the present invention is not limited to the above-described embodiments. The scope of the present invention is indicated by each claim in the claims, taking into consideration the detailed description of the invention, and includes all modifications within the scope and meaning equivalent to the wording described therein.

REFERENCE SIGNS LIST 10 switch gear 50, 50A contamination 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 (5)

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 extracting means for extracting, from the data of the electrode resistance and humidity recorded by the recording means, a maximum 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 a current time, as a maximum humidity movement value;
an average calculation means for extracting n humidity movement maximum values from the plurality of humidity movement maximum values extracted by the extraction means in order of decreasing humidity and calculating an average value thereof;
a contamination amount estimating means for estimating the amount of contamination based on the average value calculated by the average calculating means and pre-stored contamination amount estimation information, said contamination detection device including: When the average value is AVHM (1 to n),
The contamination amount estimation means estimates the contamination amount on the surface of the electrode substrate as S (mg/cm ² ) obtained by substituting the AVHM (1 to n) into the following formula (1) stored as the contamination amount estimation information:
The soil detection device according to claim 1 . a determination means for determining a humidity value Hmax(K×n) that is a K-th multiple (K is a natural number) of the n humidity values from the top of the humidity data recorded by the recording means in order of high humidity;
and a sensitivity estimation means for estimating a detection sensitivity of the amount of contamination based on the humidity value Hmax(K×n) specified by the specifying means,
The sensitivity estimation means estimates the detection sensitivity of the amount of contamination as S′ (mg/cm ² ) obtained by substituting the humidity value Hmax (K×n) into the following formula (2) that is stored in advance:
The soil detection device according to claim 2 . the pair of electrodes is disposed on a surface of the electrode substrate;
The soil detection device according to claim 1 , wherein the humidity sensor is disposed on a surface of the electrode substrate opposite to a surface on which the electrodes are formed. The electrode spacing in the electrode substrate is 0.5 mm or more and 2.0 mm or less,
The soil detection device according to claim 1 , wherein an electrode width on the electrode substrate is 10 to 40 times the electrode spacing.