Contamination detection device and contamination detection method

Abstract

The present invention provides a contamination detection method and contamination detection device capable of detecting the progression of contamination in electrical equipment placed inside electrical facilities. [Solution] The contamination detection device includes a dust accumulation sensor 102 for measuring the degree of dust accumulation, a humidity sensor 104, an electrode unit 106 having a pair of electrodes, and a control unit 160. The control unit repeatedly measures the degree of dust accumulation, humidity, and resistance between the pair of electrodes, stores the time-series data for each, determines a first representative value of the data included in the first period from the time-series data of the degree of accumulation while shifting the first period, determines a second representative value of the data included in the second period from the time-series data of humidity while shifting the second period, maps a first point representing the first and second representative values ​​corresponding to the same timing, maps a second point representing the first and second representative values ​​corresponding to the timing when resistance below a first threshold was measured, and determines the contamination level based on the first and second images.

Description

Technical Field

[0001] The present invention relates to a contamination detection device and a contamination detection method for detecting the progress of contamination in electrical equipment arranged inside electrical facilities or the like.

Background Art

[0002] Inside electrical facilities or the like, when dust enters from the outside and accumulates, the electrical equipment arranged inside thereof becomes contaminated, increasing the risk of malfunction and reduced insulation. In order to ensure the normal operation and insulation of electrical equipment, it is necessary to take measures such as regular cleaning. Note that insulation means electrical insulation.

[0003] Techniques for detecting the degree of contamination are known. For example, in Patent Document 1 below, when estimating the amount of contamination of an insulator or the like based on the surface resistivity of an electrode substrate provided with a pair of electrodes and the relative humidity around the electrode substrate, the amount of contamination (equivalent salt adhesion amount) is estimated from the relationship between the maximum value of the relative humidity over a certain period and the surface resistivity. Also, in Patent Document 2 below, a method for detecting the occurrence of insulation degradation between a pair of electrodes and estimating the amount of salt adhesion from the resistance value between the electrodes and the relative humidity is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent documents 1 and 2 disclose a technique for detecting contamination (salt deposits) as a change in resistance and estimating the amount of deposits in conjunction with humidity, but do not directly measure the contamination itself (i.e., dust accumulation). Therefore, it is not possible to accurately detect the progression of contamination until insulation degradation is confirmed by electrodes. When a salt deposit amount exceeding a predetermined value is detected and insulation degradation is confirmed, an alarm is issued and cleaning is recommended. In order to carry out planned maintenance (including cleaning), it is preferable to be able to determine the timing of cleaning at an earlier stage.

[0006] Therefore, the present invention aims to provide a contamination detection device and contamination detection method that can detect the progression of contamination in electrical equipment placed inside electrical facilities and the like. [Means for solving the problem]

[0007] (1) A contamination detection device according to the first aspect of the present invention includes a dust accumulation sensor for measuring the degree of dust accumulation, a first humidity sensor, a pair of electrodes, and a control unit, wherein the dust accumulation sensor, the first humidity sensor, and the pair of electrodes are arranged in a predetermined space, and the control unit repeatedly performs measurements by the dust accumulation sensor and the first humidity sensor and measurements of the resistance value between the pair of electrodes at predetermined timings, stores each measured value as time-series data, and processes the time-series data of the degree of accumulation, determining a first representative value of the data included in the first period while shifting the first period, First, a first time series data is generated, and the humidity time series data is used as the processing target. A second representative value of the data included in the second period is determined by shifting the second period, thereby generating a second time series data. A first image is displayed by two-dimensionally mapping a first point representing the first and second representative values ​​corresponding to the same timing. A second image is displayed by two-dimensionally mapping a second point representing the first and second representative values ​​corresponding to the timing when the resistance value below the first threshold was measured. Based on the first and second images, the contamination level can be determined. This makes it possible to detect the progression of contamination in electrical equipment placed inside electrical facilities.

[0008] (2) In (1) above, the first period is between 1 and 3 days, the second period is between 6 hours and 2 days, the first representative value is the median of the data included in the first period, and the second representative value is the maximum value of the data included in the second period. This cancels out short-term fluctuations in the measured value of the degree of dust accumulation, eliminates delays in the recovery of resistance values ​​to humidity decreases, and enables accurate detection of contamination.

[0009] (3) In (1) or (2) above, the control unit determines whether the contamination level is level 1, which represents a state where contamination has progressed one step from level 0, including a state with no contamination, by whether or not there is a first point in the first image that represents a first representative value that is less than the second threshold; whether or not there is a first point in the first image that represents a first representative value that is less than the third threshold, which is smaller than the second threshold, by whether or not there is a first point in the first image that represents a state where contamination has progressed two steps from level 0; whether or not there is a second point in the second image that represents a state where contamination has progressed three steps from level 0; and whether or not there is a second point in the second image that represents a second representative value that is less than or equal to the fourth threshold, by whether or not there is a second point in the second image that represents a second representative value that is less than or equal to the fourth threshold, by whether or not there is a second point in the second image that represents a state where contamination has progressed four steps from level 0.

[0010] (4) In any one of (1) to (3) above, the contamination detection device further includes a second humidity sensor for measuring the humidity around electrical equipment located in a space adjacent to a predetermined space, and the control unit repeatedly performs measurements by the second humidity sensor at the above timing, stores the measured humidity as time-series data, and determines the third representative value as the maximum value of the most recent data in a predetermined period from the time-series data stored by the measurement by the second humidity sensor, or the average value of a predetermined number of data selected in descending order from the data in the predetermined period, and the contamination level can be determined based on the first image and the second image, the minimum value of the second representative value represented by a second point included in the second image, and the third representative value. This makes it possible to detect the progress of contamination in electrical equipment located inside electrical facilities, etc., with greater accuracy.

[0011] In (4) above, the control unit may determine the contamination level based on the first image, the second image, the minimum value Hzmin of the second representative value represented by the second point included in the second image, and the third representative value Hmax. The control unit may determine whether the contamination level is level 4, which represents a state where contamination has progressed four levels from level 0, which includes a state of no contamination, based on whether the third representative value Hmax is greater than the value obtained by subtracting a predetermined margin ΔH from the minimum value Hzmin. This makes it possible to detect the progression of contamination in electrical equipment placed inside electrical facilities with even greater accuracy.

[0012] (5) A contamination detection method according to a second aspect of the present invention includes: a dust measurement step of repeatedly measuring the degree of dust accumulation in a predetermined space at predetermined timings and storing the measured degree of accumulation as time-series data; a first humidity measurement step of repeatedly measuring the humidity in a predetermined space at the above timings and storing the measured humidity as time-series data; a resistance measurement step of repeatedly measuring the resistance between a pair of electrodes arranged in a predetermined space at the above timings and storing the measured resistance as time-series data; and a first representative value of the data included in the first period, with the time-series data of the degree of accumulation as the processing target, while shifting the first period. This process includes the steps of generating first time-series data, generating second time-series data by processing the humidity time-series data and determining a second representative value of the data included in the second period while shifting the second period, displaying a first image by two-dimensionally mapping first points representing the first and second representative values ​​corresponding to the same timing, and displaying a second image by two-dimensionally mapping second points representing the first and second representative values ​​corresponding to the timing when the resistance below the first threshold was measured. Based on the first and second images, the contamination level can be determined. This makes it possible to detect the progression of contamination in electrical equipment placed inside electrical facilities.

[0013] In (5) above, the contamination detection method may further include a second humidity measurement step in which humidity is measured around electrical equipment located in a space separated from a predetermined space, and the measured values ​​are stored as time-series data, and a third representative value in which the maximum value of the most recent data in a predetermined period, or the average value of a predetermined number of data selected in descending order from the data in the predetermined period, is determined from the time-series data stored in the second humidity measurement step, and the contamination level may be determined based on the first image and the second image, the minimum value of the second representative value represented by a second point included in the second image, and the third representative value. This makes it possible to detect the progression of contamination in electrical equipment located inside electrical facilities, etc., with greater accuracy.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a contamination detection device and a contamination detection method capable of detecting the progress of contamination in an electric device disposed inside electrical equipment or the like.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a contamination detection device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing a configuration in which each sensor is arranged in an electric device installation area. [Figure 3] FIG. 3 is a cross-sectional view showing a light detection system of a dust deposition sensor included in the contamination detection device shown in FIG. 1. [Figure 4] FIG. 4 is a circuit diagram showing a light detection system of a dust deposition sensor included in the contamination detection device shown in FIG. 1. [Figure 5] FIG. 5 is a plan view showing an electrode portion included in the contamination detection device shown in FIG. 1. [Figure 6] FIG. 6 is a block diagram showing a configuration of the control device shown in FIG. 1. [Figure 7] FIG. 7 is a flowchart showing a process executed by the control device shown in FIG. 1. [Figure 8] FIG. 8 is a flowchart showing a contamination level determination process executed by the control device shown in FIG. 1. [Figure 9] FIG. 9 is a cross-sectional view showing an arrangement of a light detection system according to a modified example. [Figure 10] FIG. 10 is a block diagram showing a schematic configuration of a contamination detection device according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a block diagram showing a configuration of the control device shown in FIG. 10. [Figure 12] FIG. 12 is a flowchart showing a process executed by the control device shown in FIG. 10. [Figure 13]FIG. 13 is a flowchart showing the contamination level determination process executed by the control device shown in FIG. 10. [Figure 14] FIG. 14 is a graph showing the degree of dust deposition measured by the contamination detection device shown in FIG. 10. [Figure 15] FIG. 15 is a graph showing the humidity measured by the contamination detection device shown in FIG. 10. [Figure 16] FIG. 16 is a graph showing the resistance of the electrode part measured by the contamination detection device shown in FIG. 10. [Figure 17] FIG. 17 is a graph showing the moving median of the degree of dust deposition generated from the measured values shown in FIG. 14. [Figure 18] FIG. 18 is a graph showing the moving maximum value of humidity generated from the measured values shown in FIG. 15. [Figure 19] FIG. 19 is an image showing the result of mapping the data from the start of measurement to January 8, 2022 among the data shown in FIGS. 17 and 18. [Figure 20] FIG. 20 is an image showing the result of mapping the data from the start of measurement to August 3, 2022 among the data shown in FIGS. 17 and 18. [Figure 21] FIG. 21 is an image showing the result of mapping the data from the start of measurement to November 4, 2022 among the data shown in FIGS. 17 and 18. [Figure 22] FIG. 22 is an image showing the result of mapping all the data shown in FIGS. 17 and 18. [Figure 23] FIG. 23 is an image showing the result of mapping the data corresponding to the resistance value of the electrode part less than 900 kΩ among the data from the start of measurement to August 3, 2022 shown in FIGS. 17 and 18. [Figure 24] FIG. 24 is an image showing the result of mapping the data corresponding to the resistance value of the electrode part less than 900 kΩ among the data from the start of measurement to November 4, 2022 shown in FIGS. 17 and 18. [Figure 25]Figure 25 is an image showing the results of mapping the data corresponding to the resistance values ​​of the electrode section less than 900 kΩ from all the data shown in Figures 17 and 18. [Figure 26] Figure 26 is a graph showing the humidity of the electrical equipment installation area as measured by the contamination detection device shown in Figure 10. [Modes for carrying out the invention]

[0016] In the following embodiments, identical parts are assigned the same reference numeral. Their names and functions are also identical. Therefore, detailed descriptions of them will not be repeated.

[0017] (First Embodiment) (Device configuration) Referring to Figure 1, the contamination detection device 100 according to the first embodiment of the present invention includes a dust accumulation sensor 102, a humidity sensor 104, an electrode unit 106, a control device 110, and a display device 112. The contamination detection device 100 is located inside the electrical equipment 200, except for the display device 112. The electrical equipment 200 is provided with an electrical equipment installation area 202 where electrical equipment (not shown) is installed. The electrical equipment 200 is, for example, a switchgear installed outdoors. A switchgear is a device that receives a predetermined voltage to safely supply electricity, transforms it to a voltage that is easy to use, and distributes it to each load. The electrical equipment 200 can be any electrical equipment that has electrical equipment inside. The control device 110 performs measurements using the dust accumulation sensor 102, the humidity sensor 104, and the electrode unit 106.

[0018] Of the contamination detection device 100, at least the dust accumulation sensor 102, the humidity sensor 104, and the electrode unit 106 are arranged in close proximity to each other in a predetermined space within the electrical equipment 200. The control device 110 may be arranged in close proximity to the dust accumulation sensor 102, the humidity sensor 104, and the electrode unit 106, or it may be arranged at a distance from the dust accumulation sensor 102, the humidity sensor 104, and the electrode unit 106. The display device 112 is, for example, a liquid crystal panel and is arranged outside the electrical equipment 200 (for example, on an exterior wall). Both the control device 110 and the display device 112 may be arranged in a control room at a distance from the electrical equipment 200. The control device 110 and the display device 112 may be implemented, for example, by a computer located in the control room.

[0019] For the purpose of detecting signs of insulation degradation, it is preferable to position the dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 in a location within the electrical equipment 200 that is susceptible to dust accumulation and where humidity tends to rise. For example, as shown in Figure 1, the dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 are positioned near the vent 204 and away from the electrical equipment installation area 202. It is also preferable to position the dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 in the lower part of the electrical equipment 200. In the electrical equipment installation area 202, in a location close to the electrical equipment installation area 202, or in the upper part of the electrical equipment 200, the heat generated by the electrical equipment in the electrical equipment installation area 202 may affect the dew point and decrease humidity due to the rise in temperature. This is because performing measurements under high humidity conditions increases sensitivity in detecting insulation degradation of the electrode unit 106, as will be described later. The dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 may be installed within the electrical equipment installation area 202, for example, as shown in Figure 2. In this case, while it is inferior to the above (installation near the ventilation opening) in terms of predictive detection, it allows for monitoring of insulation degradation, taking into account equipment heat generation conditions, and is closer to the actual electrical equipment installation conditions.

[0020] Referring to Figure 3, the dust accumulation sensor 102 includes a light-emitting unit 120, a light-detecting unit 122, and a light-reflecting member 124. The light-emitting unit 120 is powered by a power supply unit 166, which will be described later, and emits light. The light-emitting unit 120 is, for example, a light-emitting diode (hereinafter referred to as LED). For example, a red-emitting LED (center frequency 630 nm) can be used for the light-emitting unit 120. The light-emitting unit 120 is not limited to an LED, but can be any light-emitting element that can stably output light of a predetermined intensity in a predetermined direction for a predetermined time (for example, from 1 second to several seconds). The wavelength of the light emitted from the light-emitting unit 120 can be any wavelength that can be detected by the light-detecting unit 122. The light emitted from the light-emitting unit 120 is, for example, infrared, visible light, or ultraviolet light.

[0021] The light detection unit 122 is, for example, a phototransistor. The light detection unit 122 is not limited to a phototransistor; any element that can detect light and output an electrical signal (e.g., voltage or current) of a magnitude corresponding to its intensity (amount of light) is acceptable. Preferably, the light detection unit 122 has the central wavelength of the light emitted from the light-emitting unit 120 near the center of the detection sensitivity.

[0022] The light-reflecting member 124 is held by a holding member 126 and reflects light emitted from the light-emitting unit 120, directing it into the light-detecting unit 122. The light-reflecting member 124 is formed in an L-shape in cross-section, allowing the optical path from the light-emitting unit 120 to the light-detecting unit 122 to be contained within a relatively narrow space. The two orthogonal surfaces on the light-emitting unit 120 side are mirror surfaces that reflect light from the light-emitting unit 120. For the light-reflecting member 124, for example, a BA (Bright Annealing: a finish that gives the surface a near-mirror-like luster) material of stainless steel SUS304 can be used. The surface finish is not limited to BA; it may also be electropolished. The light-reflecting member 124 only needs to be arranged so that its two reflective surfaces form approximately 90°, and can be formed, for example, by bending a metal plate. The light-reflecting member 124 may also be formed by joining two planar members having reflective surfaces at approximately orthogonal angles. The light-emitting unit 120, the light-detecting unit 122, and the light-reflecting member 124 constitute a light detection system. The light-emitting unit 120 and the light-detecting unit 122 can be realized, for example, by a photoreflector, which is an element that houses an LED and a phototransistor in a single package. This reduces the number of components and allows for a compact light detection system.

[0023] Figure 4 shows an example of a light detection system circuit using an LED in the light-emitting section 120 and a phototransistor in the light-detecting section 122. Referring to Figure 4, the light-emitting section 120 includes an LED 132 and a resistor R1 connected in series between terminals 140 and 142. In Figure 4, the light-reflecting member 124 is shown as a flat plate for convenience. The light-detecting section 122 includes a phototransistor 134, resistors R2 and R3 connected in series between terminals 144 and 146. With terminals 142 and 146 grounded, applying a DC voltage between terminals 140 and 142 of the light-emitting section 120 causes the LED 132 to emit light. When a predetermined DC voltage is applied between terminals 144 and 146, the phototransistor 134 turns on and current flows (current flows between terminals 144 and 146) when light (radiation light from the light-emitting unit 120 reflected by the light-reflecting member 124) is incident on the phototransistor 134. The resulting voltage drop generates a voltage at the measurement terminal 136.

[0024] The current flowing through the phototransistor 134 depends on the amount of light incident on the phototransistor 134, and the voltage measured at the measurement terminal 136 also depends on the amount of light incident on the phototransistor 134. As shown in Figure 1, if dust 190 accumulates on the light reflecting member 124, the amount of light incident on the phototransistor 134 (light detection unit 122) decreases, and the current flowing through the phototransistor 134 decreases. This causes the voltage at the measurement terminal 136 to decrease. Since the amount of light incident on the phototransistor 134 (light detection unit 122) depends on the amount of dust 190 accumulation, the voltage at the measurement terminal 136 also depends on the amount of dust 190 accumulation. If the amount of dust 190 accumulation increases (for example, the thickness of the dust 190 increases), the voltage at the measurement terminal 136 decreases further. Therefore, the voltage at the measurement terminal 136 can be used as a value representing the amount of dust 190 accumulation. That is, the voltage at the measurement terminal 136 is measured as the amount of dust 190 accumulation. Note that resistors R1, R2, and R3 only need to have appropriate resistance values ​​corresponding to the LED 132 and phototransistor 134.

[0025] When measuring the degree of dust accumulation using the configurations shown in Figures 3 and 4, it is necessary to consider variations in the characteristics of the elements used as LED 132 and phototransistor 134, as well as errors in the mounting positions of these elements and the light-reflecting member 124. For these reasons, even with the same degree of dust accumulation 190, the voltage at the measurement terminal 136 will be a different value, and the value representing the degree of dust accumulation will fluctuate. To avoid this, the voltage value at the measurement terminal 136 should be measured when no dust 190 has accumulated, and this voltage value should be used as a reference value to calculate the degree of dust accumulation from the voltage value at the measurement terminal 136. For example, the ratio of the measured voltage value at the measurement terminal 136 to the reference value can be used as the degree of dust accumulation.

[0026] The humidity sensor 104 is, for example, a capacitive humidity sensor or an electrical resistance humidity sensor, and outputs an analog or digital signal as relative humidity (unit: %RH). In the following, humidity means relative humidity. The humidity sensor 104 may be a surface-mountable element. If it is a surface-mountable element, it can be formed integrally with the electrode part 106. By forming the humidity sensor 104 integrally with the electrode part 106, the humidity sensor 104 and the electrode part 106 can be placed in close proximity, and the temperature difference between them can be minimized.

[0027] Referring to Figure 5, the electrode section 106 includes a substrate 150 and a pair of electrodes 152 and 154. The substrate 150 is formed of an insulating material such as resin, ceramic, or glass epoxy. Electrodes 152 and 154 are formed of a conductive material such as metal and are arranged on one surface of the substrate 150 as a predetermined electrode pattern. For example, the electrode section 106 can be formed by etching a copper-clad laminate substrate on which copper foil is arranged on the surface of the substrate. By forming electrodes 152 and 154 in a comb-like shape as shown in Figure 5, the electrode section 106 can be made compact. The electrode spacing D is, for example, 1 mm or more and 4 mm or less. The electrode width is calculated by the length W of the opposing portion of the pair of electrodes × the number of electrode spacings (in Figure 5, "7"). The electrode width is, for example, 30 mm or more and 100 mm or less. Note that the electrode shape of the pair of electrodes is not limited to a comb shape, and may be, for example, two concentric electrodes. As described above, the electrode portion 106 may be placed on the surface of the substrate 150 (the surface on which electrodes 152 and 154 are arranged, or the back surface thereof).

[0028] Referring to Figure 6, the control device 110 includes a control unit 160, a storage unit 162, an IF unit 164, a power supply unit 166, and a timer 168. The control unit 160 is, for example, a CPU (Central Processing Unit). The control unit 160 controls each part of the control device 110. The storage unit 162 is a rewritable volatile or non-volatile memory. The storage unit 162 may be a mass storage device such as a hard disk drive. The storage unit 162 stores programs executed by the control unit 160 and stores data input from the control unit 160. The IF unit 164 reads image data (digital data) stored in the storage unit 162, converts it into an analog signal (for example, an RGB signal for displaying a color image), and outputs it to the display device 112. The timer 168 receives a request from the control unit 160 and outputs information representing the current time (hereinafter also simply referred to as the current time).

[0029] The power supply unit 166 supplies power to the light-emitting unit 120 and the electrode unit 106. When the dust accumulation sensor 102 performs measurements, the power supply unit 166, under the control of the control unit 160, supplies power to the light-emitting unit 120 to operate it. When the control unit 160 outputs a high-level signal (e.g., 5V) to the power supply unit 166, the power supply unit 166 supplies power to the light-emitting unit 120. As a result, the light-emitting unit 120 lights up. When the control unit 160 outputs a low-level signal (e.g., 0V) to the power supply unit 166, the power supply unit 166 stops supplying power to the light-emitting unit 120. As a result, the light-emitting unit 120, which was lit, turns off. Furthermore, when measuring the resistance of the electrode section 106, the power supply unit 166, under the control of the control unit 160, applies a predetermined DC voltage between electrodes 152 and 154 of the electrode section 106, calculates the resistance (insulation resistance) between electrodes 152 and 154, and outputs it to the control unit 160. The power supply unit 166 outputs the resistance between electrodes 152 and 154 as, for example, digital data. If the insulation between the electrodes has not deteriorated, the measured resistance of the electrode section 106 will be 1000kΩ or more. If the measured resistance of the electrode section 106 is, for example, less than 900kΩ, it can be determined that a deterioration in insulation between the electrodes has occurred.

[0030] The control unit 160 acquires the output signal of the photodetector 122 (the degree of dust accumulation (specifically, the voltage value of the measurement terminal 136 shown in Figure 4)) and the output signal of the humidity sensor 104 (relative humidity) at predetermined timings. For example, if the photodetector 122 and humidity sensor 104 have A / D conversion functions, the control unit 160 acquires the digital data output from the photodetector 122 and humidity sensor 104. If the photodetector 122 and humidity sensor 104 output analog signals, the control unit 160 samples the input analog signals at predetermined time intervals to generate digital data.

[0031] The control device 110 may include an operating device (not shown) for inputting instructions to the control unit 160. The operating device may be, for example, a computer keyboard or mouse. The operating device may also be a touch panel located on the surface of the display device 112.

[0032] (Contamination detection process) The following describes the process of determining the degree of contamination within the electrical equipment 200 using the contamination detection device 100 shown in Figure 1, with reference to Figures 7 and 8. The process shown in Figures 7 and 8 is performed by the control unit 160 reading a predetermined program stored in the storage unit 162 and executing it.

[0033] The memory unit 162 stores information for identifying the time to perform the measurement and mapping described later (hereinafter referred to as measurement time information and mapping time information, respectively), parameters necessary for measurement, and threshold values ​​necessary for judgment processing. The measurement time information and mapping time information (collectively referred to as time information) can be arbitrarily specified according to the timing at which they are to be performed. For example, if measurement is performed at a predetermined time (including year, month, and day), the time information can be information that directly represents the time. If measurement and mapping are performed after a predetermined time has elapsed, the time information can be a time interval. For example, for measurement, the time interval Δt1 is 1 hour, and for mapping, the time interval Δt2 is 1 day. Preferably, the time information is determined according to the rate of dust accumulation, the degree of influence of dust on electrical equipment, etc. The program shown in Figure 7 is executed immediately after the contamination detection device 100 is installed in the electrical equipment 200. That is, immediately after the execution of the program, no dust has accumulated on the dust accumulation sensor 102 of the contamination detection device 100.

[0034] Referring to Figure 7, in step 400, the control unit 160 performs initial setup. Specifically, as described above, in a state where no dust has accumulated, the control unit 160 illuminates the light-emitting unit 120 and measures the signal output from the light-detecting unit 122 (voltage value at the measurement terminal 136). The measurement is performed in a state where no external light enters the electrical equipment 200. The control unit 160 calculates a coefficient α (=130 / A0) to make the measured value A0 a predetermined value (for example, 130) and stores it in the storage unit 162. After that, the control proceeds to step 402. Alternatively, the measurement may be performed multiple times, and the coefficient α may be calculated by 130 / A0 using the average of the multiple measured values ​​as A0. If the initial value is set to approximately 130 in advance, this step may be omitted. That is, if the measured value itself in a state where no dust has accumulated is within the error range and is a predetermined value (130), then it is not necessary to calculate the coefficient α (coefficient α=1).

[0035] In step 402, the control unit 160 determines whether or not to perform the measurement. That is, the control unit 160 reads the measurement time information from the storage unit 162, obtains the current time from the timer 168, and determines whether or not the timing for performing the measurement has elapsed. If it is determined that the measurement should be performed (i.e., the timing for performing the measurement has elapsed), the control proceeds to step 404. Otherwise, step 402 is repeated.

[0036] In step 404, the control unit 160 measures the degree of dust accumulation using the dust accumulation sensor 102 and stores it in the memory unit 162. Specifically, the control unit 160 emits light from the light-emitting unit 120 and measures the signal output from the light-detecting unit 122 (voltage value at the measurement terminal 136). The measurement is performed in a state where no external light enters the electrical equipment 200. The control unit 160 reads the coefficient α from the memory unit 162 and multiplies the coefficient α by the measured value Ai. The control unit 160 obtains the current time from the timer 168 and stores the multiplication result (α × Ai) in the memory unit 162 in correspondence with the current time. After that, the control proceeds to step 406. As described later, step 404 is executed repeatedly, and time-series data of the degree of dust accumulation is stored in the memory unit 162. As a result, data such as that shown in Figure 14, which will be described later as an embodiment, is obtained. Furthermore, as mentioned above, if the initial value is set to approximately 130 in advance, the measured value Ai can be stored in the storage unit 162 in association with the current time without multiplying the coefficient α by the measured value Ai.

[0037] In step 406, the control unit 160 measures the humidity using the humidity sensor 104 and stores it in the memory unit 162. The control unit 160 stores the measured humidity in the memory unit 162, corresponding it to the current time obtained in the last executed step 404 (step 404 is executed repeatedly). After that, the control proceeds to step 408. As will be described later, step 406 is executed repeatedly, and time-series data of humidity is stored in the memory unit 162. As a result, data such as that shown in Figure 15, which will be described later as an embodiment, is obtained.

[0038] In step 408, the control unit 160 measures the resistance of the electrode unit 106 and stores it in the storage unit 162. The control unit 160 controls the power supply unit 166 to measure the resistance of the electrode unit 106 and stores the signal (resistance value) output from the power supply unit 166 in the storage unit 162, corresponding it to the current time obtained in the last executed step 404. After that, the control proceeds to step 410. As will be described later, step 408 is executed repeatedly, and time-series data of resistance values ​​is stored in the storage unit 162. As a result, data such as that shown in Figure 16, which will be described later as an embodiment, is obtained.

[0039] Since the measurements in steps 404 to 408 can be performed in a short time (a few milliseconds to about one minute), each measurement may be associated with a single time point in the period between the execution of steps 404 to 408 (for example, the current time obtained by step 404). A time difference of about one minute is sufficiently small compared to the period (time interval Δt1) during which the measurements are repeated, and therefore will not affect the mapping results described later.

[0040] In step 410, the control unit 160 reads out the time-series data stored in the storage unit 162 as step 404 is repeatedly executed, starting with the last measured data for a predetermined period (hereinafter referred to as the first period), determines the moving median as the representative value (hereinafter referred to as the first representative value), and stores it in the storage unit 162. After that, the control proceeds to step 412. The first period is, for example, 1 day or more and 3 days or less. In the time-series data of dust accumulation, the control unit 160 determines the data located in the middle (25th) when a predetermined number of consecutive data (for example, 49 data (corresponding to the number of measurements over 2 days with a time interval Δt1 of 1 hour)) are arranged in order of size as the first representative value (moving median). The control unit 160 stores the determined first representative value in the storage unit 162, associating it with the time of the last measured data among the time-series data of the first period that is the target of processing. The first representative value may be the average value of the data for the first period.

[0041] As will be described later, step 410 is executed repeatedly, and each time the degree of dust accumulation is measured, one first representative value is determined, and the memory unit 162 stores time-series data of the first representative value (moving median). This generates data such as that shown in Figure 17, which will be described later as an embodiment. Note that a predetermined number of measurement data (data corresponding to the first period) are required to determine the moving median. Therefore, if the first period has not elapsed after the program has started, the memory unit 162 will not store the data necessary for processing, and the control unit 160 will not execute the process to determine the first representative value.

[0042] While the measured level of dust accumulation tends to decrease in the long term, it can fluctuate up and down in the short term (see Figure 14). This is likely due to factors such as condensation caused by high humidity. By using a moving median as the representative value (first representative value) of the dust accumulation level, short-term fluctuations in the measured value can be canceled out (see Figure 17).

[0043] In step 412, the control unit 160 reads out the time-series data stored in the storage unit 162 as step 406 is repeatedly executed for a predetermined period (hereinafter referred to as the second period), determines a moving maximum value as a representative value (hereinafter referred to as the second representative value), and stores it in the storage unit 162. After that, the control proceeds to step 414. The second period is, for example, 6 hours or more and 2 days or less. The control unit 160 sets the maximum value of a predetermined number of consecutive data points (for example, 13 data points (corresponding to the number of measurements over 12 hours with a time interval Δt1 of 1 hour)) in the time-series data of humidity as the second representative value (moving maximum value). The control unit 160 stores the determined second representative value in the storage unit 162, associating it with the time of the last measured data among the time-series data of the second period that is the target of processing.

[0044] As will be described later, step 412 is executed repeatedly, and one second representative value is determined each time a humidity is measured, and time-series data of the second representative value (moving maximum value) is stored in the storage unit 162. This generates data such as that shown in Figure 18, which will be described later as an example. Note that a predetermined number of measurement data (data corresponding to the second period) is required to determine the moving maximum value. Therefore, if the second period has not elapsed after the start of this program, the data necessary for processing is not stored in the storage unit 162, and the control unit 160 does not execute the process to determine the second representative value.

[0045] When electrodes are contaminated by dust accumulation, a decrease in resistance between the electrodes is detected as humidity increases. In this case, it is crucial to accurately determine at what humidity level the decrease in resistance is detected. For example, if a decrease in resistance is detected at low humidity, the risk of insulation degradation due to contamination is judged to be higher. Regarding the correlation between humidity and resistance, even if the resistance between electrodes decreases due to increased humidity, it recovers (increases) when humidity decreases. However, there is a delay between the timing of humidity decrease and the timing of electrode drying and resistance recovery. Therefore, using instantaneous values ​​(the measured values ​​themselves) may result in the detection of a decrease in resistance even at low humidity. By using a moving maximum value as a representative value of humidity (second representative value), the decrease in humidity can be delayed, eliminating the delay in the timing of resistance recovery relative to the timing of humidity decrease.

[0046] In step 414, the control unit 160 determines whether or not to perform the mapping. If it is determined to perform the mapping, the control proceeds to step 416. Otherwise, the control proceeds to step 422. As described above, the timing for performing the mapping is set in advance as mapping time information and stored in the storage unit 162. For example, the mapping is performed periodically with a period (time interval Δt2) of 1 day. The control unit 160 obtains the current time from the timer 168 and determines whether or not the timing for performing the mapping has elapsed.

[0047] In step 422, the control unit 160 determines whether or not it has received an instruction to terminate. If it has received an instruction to terminate, the program terminates. Otherwise, control returns to step 402, and the above process is repeated. That is, steps 404 to 412 are repeated, and as described above, time-series data for the degree of dust accumulation, humidity, resistance value between electrodes, median value of the accumulation degree, and maximum value of the humidity are stored in the storage unit 162. An instruction to terminate is given, for example, by operating the operation unit or by turning off the power of the contamination detection device 100.

[0048] If the result of the determination in step 414 is YES, in step 416, the control unit 160 reads the first representative value (moving median) and the second representative value (moving maximum) stored in the storage unit 162 in steps 410 and 412, and maps them two-dimensionally. This mapping generates the first image. After that, the control proceeds to step 418. Specifically, the control unit 160 plots points representing the moving median and moving maximum corresponding to the same time, read from the storage unit 162, using the moving median and moving maximum as two orthogonal axes. This generates the first image, for example, as shown in Figure 19, which will be described later as an embodiment.

[0049] In step 418, the control unit 160 reads out the median and maximum movement values ​​stored in the storage unit 162 in step 410 and step 412 that correspond to resistance values ​​less than a predetermined value (hereinafter referred to as the first threshold Th1) that were stored in the storage unit 162 in step 408, and maps them in two dimensions. This mapping generates a second image. The first threshold Th1 is, for example, 900 kΩ. Thereafter, the control proceeds to step 420. Specifically, the control unit 160 plots points representing the moving median value and the moving maximum value corresponding to the time corresponding to the resistance value less than the first threshold as two axes orthogonal to each other. Thereby, for example, a second image as shown in FIG. 24 described later as an embodiment is generated.

[0050] In step 420, the control unit 160 executes a contamination level determination process. The contamination level represents the degree of contamination in stages. Here, as shown in FIG. 1, it is assumed that the dust deposition sensor 102, the humidity sensor 104, and the electrode unit 106 are arranged at a location separated from the electrical equipment installation area 202, and the degree of contamination is represented by five levels, that is, from level 0 to level 4 (level 0 is the state with the lowest degree of contamination), according to the progress of contamination. · Level 0: A state where medium contamination (medium degree of contamination state) has not been reached (including the state without contamination). Specifically, it is a state where the degree of dust deposition is equal to or greater than a predetermined second threshold K1. · Level 1: Medium contamination. Specifically, it is a state where the degree of dust deposition is less than the second threshold K1 and equal to or greater than a predetermined third threshold K2 (K2 < K1). · Level 2: Severe contamination (a state where the contamination has progressed further than medium contamination). Specifically, it is a state where the degree of dust deposition is less than the third threshold K2. · Level 3: A state where a risk of insulation degradation due to contamination has been confirmed. Specifically, it is a state where insulation degradation (for example, a resistance value less than 900 kΩ) between a pair of electrodes has been confirmed. · Level 4: A state where insulation degradation due to contamination is significant. Specifically, it is a state where the humidity is equal to or less than a predetermined fourth threshold Th2 and insulation degradation between a pair of electrodes has been confirmed.

[0051] The second threshold K1 and the third threshold K2 may be determined in advance through experiments. Regarding the degree of contamination, inspectors can visually inspect the contamination (degree of dust accumulation) of the electrical equipment and determine whether it is "moderately contaminated" or "heavily contaminated." The second threshold K1 and the third threshold K2 can be determined based on the judgment of an experienced inspector. The number of levels and the criteria for determining each level are not limited to those described above. They may differ depending on whether the purpose is to detect signs of insulation degradation or to monitor whether insulation degradation has occurred. If the purpose is to monitor whether insulation degradation has occurred and the dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 are arranged in the electrical equipment installation area 202 as shown in Figure 2, then a different number of levels and judgment criteria may be used.

[0052] As part of the contamination level determination process, the control unit 160 executes the process shown in Figure 8. Level 0 is stored in the storage unit 162 as the initial value for the contamination level. Referring to Figure 8, in step 500, the control unit 160 determines whether there are any points in the first image generated in step 416 where the moving median value is less than the second threshold K1. If there are any points where the moving median value is less than the second threshold K1, the control proceeds to step 502. Otherwise, the control proceeds to step 508. As described above, if the initial value for the degree of dust accumulation is "130", the second threshold K1 is, for example, "75".

[0053] In step 502, the control unit 160 sets the contamination level to level 1. That is, the control unit 160 changes the contamination level (level 0) stored in the memory unit 162 to level 1. After that, the control proceeds to step 504.

[0054] In step 504, the control unit 160 determines whether there are any points in the first image generated in step 416 where the median movement is less than the third threshold K2. If there are points where the median movement is less than the third threshold K2, the control proceeds to step 506. Otherwise, the control proceeds to step 508. As described above, if the initial value of the dust accumulation is "130", the third threshold K2 is, for example, "45".

[0055] In step 506, the control unit 160 sets the contamination level to level 2. That is, the control unit 160 changes the contamination level stored in the memory unit 162 to level 2. After that, the control proceeds to step 508.

[0056] In step 508, the control unit 160 determines whether there are any points plotted in the second image generated in step 418 (points representing the moving median and moving maximum values ​​corresponding to resistance values ​​less than the first threshold Th). If such points are found in the second image, the control proceeds to step 510. Otherwise, the control proceeds to step 516.

[0057] In step 510, the control unit 160 sets the contamination level to level 3. That is, the control unit 160 changes the contamination level stored in the memory unit 162 to level 3. After that, the control proceeds to step 512.

[0058] In step 512, the control unit 160 determines whether there are any points in the second image generated in step 418 where the maximum movement value is less than or equal to the fourth threshold Th2. If there are any points where the maximum movement value is less than or equal to the fourth threshold Th2, the control proceeds to step 514. Otherwise, the control proceeds to step 516. The fourth threshold K2 is, for example, 90%RH. The fourth threshold Th2 is determined, for example, by the highest humidity reached in the electrical equipment installation area 202, which has been measured in advance. The fourth threshold Th2 may also be determined based on past experience, etc., without measurement.

[0059] In step 514, the control unit 160 sets the contamination level to level 4. That is, the control unit 160 changes the contamination level stored in the memory unit 162 to level 4. After that, the control proceeds to step 516. If the dust accumulation sensor 102, humidity sensor 104, and electrode unit 106 are installed within the electrical equipment installation area 202, the presence of a plotted point in the second image indicates that there has been a decrease in insulation in the electrical equipment installation environment. That is, in the five levels from level 0 to level 4 that represent the degree of contamination as described above, level 3 is changed to level 4, and the contamination level is set to 4 without going through the processes of steps 512 and 514.

[0060] In step 516, the control unit 160 reads the contamination level from the storage unit 162 and presents it. For example, the control unit 160 displays the contamination level read from the storage unit 162 on the display device 112. If the result of the determination processes in steps 500, 504, 508, and 512 described above is YES, the contamination level stored in the storage unit 162 is overwritten, and the last overwritten contamination level is presented. After that, the control returns to the flowchart shown in Figure 7 and proceeds to step 422.

[0061] The above process is then repeated until it is determined that the process has ended in step 422. Therefore, mapping and contamination level determination are repeatedly performed at predetermined intervals, and contamination levels corresponding to the progression of contamination within the electrical equipment 200 are presented. Once the contamination level is presented, the administrator can review it and take appropriate action (for example, determine the maintenance policy for the electrical equipment 200). For example, if a contamination level of level 2 or level 3 is presented, the administrator plans to clean the inside of the electrical equipment 200 during the next maintenance. If a contamination level of level 4 is presented, the administrator may carry out cleaning immediately.

[0062] Generally, equipment maintenance (inspection) is performed regularly, but whether or not cleaning is performed during this time varies depending on the user. As mentioned above, by constantly monitoring the level of contamination and periodically presenting the contamination level, maintenance can be made more efficient for users who perform cleaning with each maintenance. For example, if it is determined just before maintenance that the contamination level is not high and the contamination is not progressing, cleaning can be reduced (not performed) during maintenance, thereby making maintenance more efficient. For users who do not perform cleaning during maintenance, the need for cleaning can be communicated at the appropriate time. If cleaning is performed in response to this, the risk of equipment malfunction can be reduced.

[0063] The process in step 500 is equivalent to determining whether the time-series data of the moving median stored in the storage unit 162 contains values ​​less than the second threshold K1, that is, whether the minimum value of the time-series data of the moving median is less than the second threshold K1. The process in step 504 is equivalent to determining whether the time-series data of the moving median stored in the storage unit 162 contains values ​​less than the third threshold K2, that is, whether the minimum value of the time-series data of the moving median is less than the third threshold K2. The process in step 508 is equivalent to determining whether the time-series data of the electrode resistance values ​​stored in the storage unit 162 contains values ​​less than the first threshold Th1, that is, whether the minimum value of the time-series data of the resistance values ​​is less than the first threshold Th1. The process in step 512 is equivalent to determining whether the time-series data of the moving maximum value stored in the storage unit 162 contains values ​​less than or equal to the fourth threshold Th2, that is, whether the minimum value Hzmin of the time-series data of the moving maximum value is less than or equal to the fourth threshold Th2 (Hzmin ≤ Th2). Therefore, if the control unit 160 determines the level of contamination, steps 416 and 418 do not need to be performed.

[0064] The contamination level determination process shown in Figure 8 may be performed by a human. For example, the manager of the electrical equipment 200 can determine the contamination level by visually inspecting the first and second images mapped in steps 416 and 418. That is, the manager can determine the contamination level as described with respect to steps 500, 504, 508 and 512 in Figure 8. In order to facilitate visual determination of the contamination level, it is preferable to display figures indicating the threshold values ​​(K1, K2 and Th2) used for determination superimposed on the first and second images, as will be described later as an embodiment.

[0065] Figure 8 illustrates the case where steps 500, 504, 508, and 512, which determine each contamination level, are executed in order, but is not limited to this. The order in which steps 500, 504, 508, and 512 are executed may be arbitrary. Steps 500, 504, 508, and 512 may also be executed in parallel. In that case, the contamination levels set by the step executed when the determination result of each step is YES are stored as provisional levels in different areas of the memory unit 162, and finally, the contamination level with the largest value among the four provisional levels can be determined.

[0066] (modified version) In the above description, a configuration was explained in which dust is deposited on a light-reflecting member formed in an L-shape in cross-section, and the emitted light from the light-emitting unit 120 is reflected twice and detected by the light-detecting unit 122. However, the system is not limited to this configuration. Any configuration is available for forming the optical path through which the dust passes. In Figure 3, the light-reflecting member 124 may be replaced with a flat light-reflecting member, dust may be deposited on it, and the emitted light from the light-emitting unit 120 may be reflected once and detected by the light-detecting unit 122. The light-detecting unit 122 only needs to be positioned in a location where it can receive the light from the emitted light of the light-emitting unit 120 that has been reflected by the flat light-reflecting member.

[0067] Alternatively, dust may be deposited on the light-transmitting member, allowing the light emitted from the light-emitting unit 120 to pass through and be detected by the light-detecting unit 122. For example, as shown in Figure 9, the configuration may be such that light from the light-emitting unit 120 passes through the dust 190 and is then detected by the light-detecting unit 122. A flat light-transmitting member 220 is placed between the light-emitting unit 120 and the light-detecting unit 122. The light-transmitting member 220 is held around its periphery by a flat holding member 222, which in turn is held on a flat portion 226 of the electrical equipment 200 by, for example, a plurality of columnar support members 224.

[0068] Furthermore, the light detection circuit is not limited to the circuit shown in Figure 4. That is, the light detection unit is not limited to a configuration in which the phototransistor 134 and two resistors are directly connected (resistors R2 and R3 in Figure 4). Any configuration that includes the phototransistor 134 and at least one resistor and can detect changes in the current value flowing through the phototransistor 134 as a change in the voltage drop across the resistor is acceptable. Depending on the amount of dust 190 accumulated, the amount of light received by the phototransistor 134 changes, and the change in the current value flowing through the phototransistor 134 in response to the change in light amount can be detected as a change in the voltage drop.

[0069] (Second Embodiment) In electrical equipment placed within the electrical equipment 200, the humidity around the electrical equipment decreases due to the heat generated by the electrical equipment itself. This point is not taken into consideration in the first embodiment. In contrast, in the second embodiment, contamination is detected by also taking into consideration the decrease in humidity around the electrical equipment.

[0070] (Device configuration) Referring to Figure 10, the contamination detection device 180 according to the second embodiment of the present invention includes a dust accumulation sensor 102, a first humidity sensor 182, an electrode unit 106, a control device 184, a display device 112, and a second humidity sensor 186. The contamination detection device 180 is arranged within the electrical equipment 200, similar to the contamination detection device 100. The control device 184 performs measurements using the dust accumulation sensor 102, the first humidity sensor 182, the electrode unit 106, and the second humidity sensor 186. The contamination detection device 180 is the same as the contamination detection device 100 shown in Figure 1, but with the humidity sensor 104 and control device 110 replaced by the first humidity sensor 182 and control device 184, respectively, and the second humidity sensor 186 added. Since the contamination detection device 180 includes the second humidity sensor 186, for convenience, "humidity sensor 104" is referred to as "first humidity sensor 182". The first humidity sensor 182 is the same as the humidity sensor 104. Referring to Figure 11, the control device 184 includes a control unit 188, a storage unit 162, an IF unit 164, a power supply unit 166, and a timer 168. The control device 184 is the same as the control device 110 shown in Figure 6, but with the control unit 160 replaced by the control unit 188. Therefore, without repeating explanations, the following will mainly describe the differences.

[0071] Similar to the contamination detection device 100, at least the dust accumulation sensor 102, the first humidity sensor 182, and the electrode unit 106 of the contamination detection device 180 are arranged in close proximity to each other. The second humidity sensor 186 is located near electrical equipment installed within the electrical equipment installation area 202. The second humidity sensor 186, like the humidity sensor 104, is, for example, a capacitive humidity sensor or an electrical resistance humidity sensor, and outputs an analog or digital signal as relative humidity (in %RH).

[0072] Referring to Figure 11, the control unit 188, like the control unit 160, is, for example, a CPU and controls each part of the control device 184. The control unit 188 reads and executes the program stored in the memory unit 162 and outputs the data to the memory unit 162 for storage. The control unit 188 obtains the current time from the timer 168. At predetermined timings, the control unit 188 controls the power supply unit 166 and obtains the output signal of the light detection unit 122, the resistance value between electrodes 152 and 154 of the electrode unit 106, and the output signals (relative humidity) of the first humidity sensor 182 and the second humidity sensor 186.

[0073] (Contamination detection process) The following describes the process of determining the degree of contamination within the electrical equipment 200 using the contamination detection device 180 shown in Figure 10, with reference to Figures 12 and 13. The processes shown in Figures 12 and 13 are performed by the control unit 188 reading and executing a predetermined program stored in the storage unit 162. In Figure 12, steps 406 and 412 are replaced by steps 430 and 432, respectively, and step 420 is replaced by steps 434 and 436, as shown in the flowchart in Figure 7. In Figure 13, step 512 is replaced by step 530, as shown in the flowchart in Figure 8. The processes in steps with the same reference numerals are the same. In the following, we will avoid repeating explanations and mainly describe the differences.

[0074] Referring to Figure 12, after the initial setup is performed in step 400, if it is determined in step 402 to perform a measurement, the degree of dust accumulation is measured in step 404. Subsequently, in step 430, the control unit 188 measures the humidity (referred to as the first humidity and second humidity, respectively) using the first humidity sensor 182 and the second humidity sensor 186, and stores them in the storage unit 162. The control unit 188 stores the measured first and second humidity in the storage unit 162, corresponding them to the current time obtained in the last executed step 404. After that, the control proceeds to step 408. As will be described later, step 430 is executed repeatedly, and time-series data of the first and second humidity are stored in the storage unit 162. As a result, for example, data such as that shown in Figure 15 (time-series data of the first humidity) and the data shown in Figure 26 (time-series data of the second humidity), which will be described later as an embodiment, are obtained.

[0075] After measuring the resistance of the electrode section 106 in step 408 and determining the moving median value in step 410, in step 432, the control unit 188 reads the time-series data of the first humidity stored in the storage unit 162 by repeatedly executing step 430, determines the moving maximum value as the second representative value for the second period, and stores it in the storage unit 162. The processing in step 430 is substantially the same as the processing in step 412 (see Figure 6), which processes "humidity," but the processing target is "first humidity" for convenience.

[0076] Subsequently, if step 414 determines that mapping should be performed, step 416 and the mapping performed in step 416 are executed. Next, in step 434, the control unit 188 reads the time-series data of the second humidity stored in the storage unit 162 by repeatedly executing step 430, and determines the representative value of all data (hereinafter referred to as the third representative value) Hmax. The third representative value Hmax is, for example, the maximum value of all data. The control unit 188 stores the third representative value Hmax in the storage unit 162. After that, the control proceeds to step 436.

[0077] In step 436, the control unit 188 executes a contamination level determination process. Specifically, the control unit 188 executes the process shown in FIG. 13. As described above, the contamination level is represented by five levels (level 0 to level 4), and level 0 is stored in the storage unit 162 as the initial value of the contamination level. Regarding levels 0 to 3, the determination is made in the same manner as described above. The determination method for level 4 is different from the above as will be described later.

[0078] Referring to FIG. 13, steps 500 to 508 are executed. If the determination result in step 508 is NO, the control proceeds to step 516. If the determination result in step 508 is YES, the control proceeds to step 510, and the contamination level is set to level 3. Subsequently, in step 530, the control unit 188 reads the third representative value Hmax from the storage unit 162, and determines whether the third representative value Hmax is greater than a value obtained by subtracting a predetermined margin ΔH from the minimum value Hzmin of the maximum moving value of the first humidity corresponding to the points plotted in the second image generated in step 418. That is, the control unit 188 determines whether Hmax > Hzmin - ΔH. When it is determined that Hmax > Hzmin - ΔH, the control proceeds to step 514, and the contamination level is set to level 4, where the contamination has progressed the most and there is a risk of insulation degradation. Otherwise, the control proceeds to step 516, and the contamination level is presented. The margin ΔH is set to a value, for example, of 0%RH or more and 10%RH or less, and may be stored in the storage unit 162.

[0079] For example, as will be described later, referring to FIG. 26, the maximum value of the second humidity measured by the second humidity sensor 186 is 82%RH (the third representative value Hmax), and referring to FIG. 25, the minimum value Hzmin of the maximum moving value of the first humidity corresponding to the points plotted in the second image is 88%RH. When the margin ΔH is 3%RH, Hmax (82%RH) < Hzmin - ΔH (88%RH - 3%RH = 85%RH), the determination result in step 530 is NO, the contamination level is not changed, the control proceeds to step 516, and the contamination level determined before step 510 is presented.

[0080] As described above, similar to the first embodiment, the above-described process is repeated until it is determined in step 422 that the process ends. At a predetermined timing, mapping and determination of the contamination level are repeatedly executed, and a contamination level corresponding to the progress of contamination within the electrical equipment 200 is presented. When the contamination level is presented, the administrator can view it and take corresponding actions according to the presented contamination level. Also, as described above, for users who perform cleaning every maintenance, the efficiency of maintenance can be improved. For users who do not perform cleaning during maintenance, the necessity of cleaning at an appropriate time can be notified, and the risk of equipment malfunctions can be reduced.

[0081] In the first embodiment, the maximum moving value of the humidity (first humidity) measured by the first humidity sensor 182 disposed apart from the electrical equipment installation area 202 is compared with the fourth threshold Th2 to determine the contamination level (see step 512 in FIG. 8). In contrast, in the second embodiment, the measured value of the humidity (second humidity) near the electrical equipment installed in the electrical equipment installation area 202 is also used to determine the contamination level (see step 530 in FIG. 13). As a result, the determination accuracy of the contamination level becomes higher. The determination formula Hmax>Hzmin - ΔH in step 530 can be rewritten as Hzmin<Hmax + ΔH. Therefore, step 530 in FIG. 13 can be interpreted as substituting the fourth threshold Th2 with Hmax + ΔH in step 512 in FIG. 8, and it can be said that the contamination level is determined using a more appropriate threshold. By appropriately setting ΔH and using the measured value of the second humidity, the determination accuracy of the contamination level can be further increased.

[0082] The third representative value Hmax determined in step 434 does not have to be the maximum value of all data in the time series data for the second humidity. The maximum value of the time series data for the second humidity measured from the present to a predetermined time in the past (for example, one year ago) may be used as the third representative value Hmax. It is preferable to use time series data for a period of at least one year and use the maximum value as the third representative value Hmax. Alternatively, instead of the maximum value, a predetermined number of data (for example, 10) are selected from the time series data for the second humidity in descending order, and their average value is calculated and used as the third representative value Hmax.

[0083] The above explanation described cases where contamination detection is performed within electrical equipment such as switchgear, but it is not limited to this. Any space (such as a small room) where electrical equipment is located, is surrounded on all six sides by walls, etc., and has ventilation to the outside, is subject to contamination detection. [Examples]

[0084] The following experimental results demonstrate the effectiveness of the present invention. A contamination detection device 180, configured as shown in Figures 10 and 11, was placed inside an outdoor electrical facility (switchgear), and experiments were conducted from March 12, 2021, to July 5, 2023. The light-reflecting member 124 of the dust accumulation sensor 102 (see Figure 3), placed at the start of the experiment, was in a clean state with no dust accumulation. After placement, the light-emitting unit 120 was lit at regular intervals, and the voltage at the measurement terminal 136 was measured to calculate the degree of dust accumulation. The results are shown in Figure 14. At the same time, humidity was measured using the humidity sensor 104, the resistance value of the electrode unit 106 was measured, and humidity was measured using the second humidity sensor 186. The results are shown in Figures 15, 16, and 26, respectively. The electrode unit 106 used the comb-shaped electrodes 152 and 154 shown in Figure 5, with an electrode spacing of D2 mm and an electrode width of approximately 50 mm.

[0085] In Example 1, contamination detection was performed using measurement results other than the humidity measurement result from the second humidity sensor 186 (see Figure 26). The measurement result of the degree of dust accumulation from the dust accumulation sensor 102 (see Figure 14), the humidity measurement result from the humidity sensor 104 (see Figure 15), and the resistance measurement result from the electrode unit 106 (see Figure 16) can be interpreted as measurement results from the contamination detection device 100 with the configuration shown in Figures 1 to 6. In Figure 14, the vertical axis represents the degree of dust accumulation, and the horizontal axis represents the measurement date and time. The degree of dust accumulation was calculated by multiplying the measured voltage (generated voltage) generated at the measurement terminal 136 by the phototransistor 134 included in the light detection unit 122 by the coefficient α described above. That is, the degree of dust accumulation (voltage) is a relative value converted by setting the voltage value of the measurement terminal 136 in a state where no dust has accumulated on the light reflecting member 124 to "130". The graph in Figure 14 shows that the degree of dust accumulation is on a long-term downward trend. Furthermore, the graph in Figure 14 shows short-term fluctuations in the degree of dust accumulation. In Figure 15, the vertical axis represents humidity (%RH), and the horizontal axis represents the same measurement date and time as in Figure 14. In Figure 16, the vertical axis represents resistance value (kΩ), and the horizontal axis represents the same measurement date and time as in Figure 14. Regarding resistance measurement, the upper limit of measurement is 1000kΩ, and even if the actual resistance value exceeds 1000kΩ, it is displayed as 1000kΩ in Figure 16. As will be described later, the moving median was determined for 2 days of measurement data, so Figures 14 to 16 show the measurement data from when the moving median could first be determined. That is, the horizontal axis starts from March 14, 2021, two days after March 12, 2021, when the measurements began.

[0086] As described above, time-series data of the moving median was generated from the time-series data of the measured dust accumulation (see Figure 14). The results are shown in Figure 17. Specifically, the time-series data for two days was arranged in order of magnitude, and the process of determining their median was repeated while shifting the target data by one along the time axis. The determined moving median was matched to the time of the last measurement in the two-day time-series data. The graph in Figure 17 shows a long-term downward trend in the dust accumulation, similar to the graph in Figure 14. In Figure 17, it can be seen that short-term fluctuations in the dust accumulation have been removed compared to Figure 14.

[0087] As described above, time-series data of the moving maximum value was generated from the measured humidity time-series data (see Figure 15). The results are shown in Figure 18. Specifically, the 12-hour time-series data was arranged in descending order of magnitude, and the process of determining the maximum value was repeated while shifting the target data one step along the time axis. The determined moving maximum value corresponds to the time of the last measurement in the 12-hour time-series data.

[0088] Figures 19 to 22 show the results of two-dimensionally mapping the median movement of the generated dust accumulation (see Figure 17) and the maximum movement of humidity (see Figure 18) over time. Figures 23 to 25 show the results of two-dimensionally mapping the data corresponding to the time when the resistance value between electrodes (see Figure 16) was less than 900 kΩ, among the median movement of the generated dust accumulation (see Figure 17) and the maximum movement of humidity (see Figure 18), over time. In Figures 19 to 25, the vertical axis represents the median movement of the dust accumulation, and the horizontal axis represents the maximum movement of humidity.

[0089] Figure 19 plots data from March 14, 2021 (hereinafter referred to as the start date) to January 8, 2022. Similarly, Figures 20 to 22 plot data from the start date to August 3, 2022, November 4, 2022, and July 5, 2023, respectively. In Figures 19 to 22, two straight lines (see dashed lines) are shown representing the second threshold K1(75) and the third threshold K2(45) for the degree of dust accumulation.

[0090] Figure 23 plots the data corresponding to resistance <900kΩ from all data from the start to August 3, 2022. Figure 23 has no plotted points, indicating that the resistance between electrodes never fell below 900kΩ from the start to August 3, 2022 (see Figure 16). Therefore, Figure 23 also maps the data from the start to January 8, 2022, and corresponds to Figures 19 and 20. Figure 24 plots the data corresponding to resistance <900kΩ from all data from the start to November 4, 2022, and corresponds to Figure 21. Figure 25 plots the data corresponding to resistance <900kΩ from all data from the start to July 5, 2023, and corresponds to Figure 22. Figures 23 to 25 show a straight line (see dashed line) representing the fourth threshold for humidity, Th2 (90%RH).

[0091] Using Figures 19 to 25, the contamination level is determined as shown in Figure 8. To determine the contamination level on January 8, 2022, refer to Figures 19 and 23. In Figure 19, all plotted points are greater than the second threshold K1. Therefore, the result of step 500 is NO. In Figure 23, there are no plotted points, and the result of step 508 is NO. Therefore, steps 502, 506, 510, and 514 are not performed, and the contamination level remains at the initial value (level 0).

[0092] To determine the contamination level on August 3, 2022, refer to Figures 20 and 23. In Figure 20, points below the second threshold K1 are plotted, but all plotted points are greater than the third threshold K2. Therefore, the result of step 500 is YES, the result of step 504 is NO, step 502 is executed, step 506 is not executed, and the contamination level is changed to level 1. In Figure 23, there are no plotted points, and the result of step 508 is NO. Therefore, steps 510 and 514 are not executed, and the contamination level is maintained at level 1.

[0093] To determine the contamination level on November 4, 2022, refer to Figures 21 and 24. In Figure 21, points below the second threshold K1 are plotted, and all plotted points are greater than or equal to the third threshold K2. Therefore, the result of step 500 is YES, the result of step 504 is NO, step 502 is executed, step 506 is not executed, and the contamination level is temporarily changed to level 1. In Figure 24, there are plotted points (see within the dashed ellipse), and all of them are greater than the fourth threshold Th2 (90%RH). Therefore, the result of step 508 is YES, and the result of step 512 is NO. As a result, step 510 is executed, step 514 is not executed, and the contamination level is changed to level 3.

[0094] To determine the contamination level on July 5, 2023, refer to Figures 22 and 25. In Figure 22, points below the third threshold K2 are plotted. Therefore, the results of steps 500 and 504 are both YES, and steps 502 and 506 are executed, changing the contamination level to level 2. In Figure 25, there are points below the fourth threshold Th2 (90%RH) (see within the dashed ellipse). Therefore, the results of steps 508 and 512 are both YES. As a result, steps 510 and 514 are executed, changing the contamination level to level 4.

[0095] As described above, the level of contamination can be determined by referring to the first and second images, which are two-dimensional maps of the median value of the degree of dust accumulation and the maximum value of humidity over time. In other words, the progression of contamination in electrical equipment placed within electrical facilities can be detected. [Examples]

[0096] In Example 2, contamination detection was performed using all measurement results, including the humidity measurement results from the second humidity sensor 186 (see Figure 26). In Figure 26, the vertical axis represents humidity (%RH), and the horizontal axis represents the same measurement date and time as in Figure 14.

[0097] Using Figures 19 to 26, the contamination level is determined as shown in Figure 13. ΔH in the determination formula in step 530 is set to 3%RH. To determine the contamination level on January 8, 2022, refer to Figures 19 and 23. As shown in Example 1, steps 502, 506, 510, and 514 are not performed, and the contamination level remains at the initial value (level 0).

[0098] Refer to Figures 20 and 23 to determine the contamination level on August 3, 2022. As shown in Example 1, of steps 502, 506, 510, and 514, only step 502 is performed, and the contamination level is changed to level 1.

[0099] To determine the contamination level on November 4, 2022, refer to FIGS. 21 and 24. As shown in Example 1, step 502 is executed, step 506 is not executed, and the contamination level is once changed to level 1. Since there are plotted points in FIG. 24, the determination result of step 508 is YES, step 510 is executed, and the contamination level is once changed to level 3. In the graph of FIG. 26, the maximum value (the third representative value Hmax) among all the data from the start time to November 4, 2022, is 82%RH. Regarding the two points plotted in FIG. 24, the minimum value Hzmin of the moving maximum value of humidity is 95%RH, and Hzmin - ΔH = 95 - 3 = 92 (%RH). Therefore, Hmax < Hzmin - ΔH, and the determination result of step 530 is NO. As a result, step 514 is not executed, and the contamination level is maintained at level 3 changed by step 510.

[0100] To determine the contamination level on July 5, 2023, refer to FIGS. 22 and 25. As shown in Example 1, steps 502 and step 506 are executed, and the contamination level is once changed to level 2. Since there are plotted points in FIG. 25, the determination result of step 508 is YES, step 510 is executed, and the contamination level is once changed to level 3. In the graph of FIG. 26, the maximum value (the third representative value Hmax) among all the data from the start time to July 5, 2023, is 82%RH. Regarding the points plotted in FIG. 25, the minimum value Hzmin of the moving maximum value of humidity is 88%RH, and Hzmin - ΔH = 88 - 3 = 85 (%RH). Therefore, Hmax < Hzmin - ΔH, and the determination result of step 530 is NO. As a result, step 514 is not executed, and the contamination level is maintained at level 3 set by step 510.

[0101] On July 5, 2023, the contamination level was determined to be level 4 in Example 1, while it was level 3 in Example 2. In Figure 25, the maximum humidity values ​​measured by the first humidity sensor 182 were all above 88%RH. That is, at high humidity levels of 88%RH or higher, the resistance value of the electrode section 106 was less than 900kΩ, indicating a high risk of insulation degradation in the electrode section 106. In contrast, the humidity measured by the second humidity sensor 186 (see Figure 26) was all below 82%RH (Hmax=82%RH), which is lower than 88%RH. Therefore, it is more appropriate to conclude that the risk of insulation degradation in the environment where the second humidity sensor 186 was located was lower than in the surrounding environment of the electrode section 106. In other words, it is more appropriate to determine the contamination level, which represents the risk of insulation degradation in electrical equipment installed in electrical facilities, to be level 3.

[0102] As described above, by referring to the first and second images, which are two-dimensional maps of the median value of dust accumulation and the maximum value of humidity over time, along with the measured humidity of the area where the electrical equipment is installed, the level of contamination can be determined with greater accuracy. In other words, the progression of contamination in electrical equipment placed inside electrical facilities can be detected with greater accuracy.

[0103] The present invention has been described above by describing embodiments, but the embodiments described above are illustrative, and the present invention is not limited to the embodiments described above. The scope of the present invention is given with reference to the description in the detailed description of the invention, and includes all modifications within the meaning and scope equivalent to the wording contained herein. [Explanation of symbols]

[0104] 100, 180 contamination detection device 102 Dust accumulation sensor 104 Humidity Sensor 106 Electrode section 110, 184 Control devices 112 Display device 120 Light-emitting part 122 Light detection unit 124 Light-reflecting member 126, 222 Retaining member 132 LED 134 Phototransistors 136 Measuring terminals Terminals 140, 142, 144, 146 150 circuit boards 152, 154 electrode 160, 188 Control Unit 162 Storage section 164 IF section 166 Power supply section 168 timers 182 First humidity sensor 186 Second humidity sensor 190 Dust 200 Electrical equipment 202 Electrical Equipment Installation Area 204 Ventilation opening 220 Light-transmitting member 224 Support Member 226 Flat area D Electrode spacing R1, R2, R3 resistance W Length

Claims

1. A dust accumulation sensor that measures the degree of dust accumulation, The first humidity sensor, A pair of electrodes, Includes a control unit, The dust accumulation sensor, the first humidity sensor, and the pair of electrodes are arranged in a predetermined space. The control unit, The measurements by the dust accumulation sensor and the first humidity sensor, and the measurement of the resistance value between the pair of electrodes are repeatedly performed at predetermined intervals, and the respective measured values ​​are stored as time-series data. By processing the aforementioned time-series data of the degree of deposition, and determining a first representative value of the data included in the first period while shifting the first period, a first time-series data is generated. The aforementioned time-series data of humidity is used as the processing target, and a second representative value of the data included in the second period is determined by shifting the second period, thereby generating a second time-series data. The first image is displayed by two-dimensionally mapping the first points representing the first representative value and the second representative value corresponding to the same timing. A second image is displayed by two-dimensionally mapping a second point representing the first representative value and the second representative value corresponding to the timing at which the resistance value below the first threshold was measured. A contamination detection device capable of determining the contamination level based on the first image and the second image.

2. The aforementioned first period is between one and three days. The second period is between 6 hours and 2 days. The first representative value is the median of the data included in the first period. The contamination detection device according to claim 1, wherein the second representative value is the maximum value of the data included in the second period.

3. The control unit, Whether or not there is a first point in the first image that represents the first representative value which is less than the second threshold is determined to determine whether or not the contamination level is level 1, which represents a state where contamination has progressed one step from level 0, which includes a state with no contamination. Whether or not there is a first point in the first image that represents the first representative value which is less than the third threshold which is smaller than the second threshold, determines whether or not the contamination level is level 2, which represents a state where contamination has progressed two levels from level 0. Whether or not the second point is present in the second image is used to determine whether the contamination level is level 3, which represents a state where contamination has progressed three levels from level 0. A contamination detection device according to claim 1 or 2, wherein the contamination level is determined to be level 4, which represents a state in which contamination has progressed four levels from level 0, based on whether or not there is a second point in the second image that represents the second representative value which is below the fourth threshold.

4. The system further includes a second humidity sensor for measuring the humidity around electrical equipment located in a space separated from the predetermined space, The control unit, The measurement by the second humidity sensor is repeatedly performed at the aforementioned timing, and the measured humidity is stored as time-series data. From the time-series data stored by the measurement of the second humidity sensor, the maximum value of the most recent data in a predetermined period, or the average value of a predetermined number of data selected in descending order from the data in the predetermined period, is determined as the third representative value. The contamination detection device according to claim 1, wherein the contamination level can be determined based on the first image and the second image, the minimum value of the second representative value represented by the second point included in the second image, and the third representative value.

5. A dust measurement step involves repeatedly measuring the degree of dust accumulation in a predetermined space at predetermined intervals, and storing the measured degree of accumulation as time-series data. A first humidity measurement step involves repeatedly measuring the humidity in the predetermined space at the specified timing and storing the measured humidity as time-series data. A resistance measurement step includes repeatedly measuring the resistance between a pair of electrodes arranged in the predetermined space at the timings described above, and storing the measured resistance as time-series data. The process involves using the aforementioned time-series data of the degree of accumulation as the target of processing, determining a first representative value of the data included in the first period while shifting the first period, thereby generating a first time-series data; The process involves generating a second time-series data by determining a second representative value of the data included in the second period, while shifting the second period, using the aforementioned time-series data of humidity as the processing target. A first display step involves displaying a first image by two-dimensionally mapping first points representing the first representative value and the second representative value corresponding to the same timing, The second display step includes displaying a second image by two-dimensionally mapping a second point representing the first representative value and the second representative value corresponding to the timing at which the resistance below the first threshold was measured, A method for detecting contamination, wherein the level of contamination can be determined based on the first image and the second image.

Images