DEVICE FOR MONITORING POLLUTION IN ELECTRICAL INSULATORS BY MEASURING LEAKAGE CURRENT AND CALCULATING SURFACE RESISTIVITY

Description

16 DEVICE FOR MONITORING POLLUTION IN ELECTRICAL INSULATORS BY MEASURING CURRENT OF Leakage and surface resistance calculation TECHNICAL FIELD

[001] The present invention falls within the field of electrical engineering, more specifically in the area of ​​monitoring and diagnosing components of electrical distribution networks in coastal regions. In particular, it refers to a device for monitoring electrical insulators, encompassing technologies for measuring surface resistivity, analyzing leakage current, and evaluating environmental conditions. The present invention proposes an improved embedded electronic device, equipped with sensors and processing algorithms, capable of measuring leakage current and calculating the surface resistivity of insulators to correlate with the severity of deposited pollution, allowing predictive maintenance and increasing the reliability of the electrical network. FUNDAMENTALS OF THE INVENTION

[002] Pollution in medium-voltage insulators represents one of the main challenges for the maintenance of electrical power distribution networks. This problem is associated with increased conductivity on the surface of the insulators, resulting in phenomena such as surface discharges and flashovers, which can lead to power outages and compromise the reliability of the electrical system. Such occurrences impact not only the operation but also the lifespan of the insulators and consequently maintenance costs, such as line inspections and insulator replacement.

[003] There are two main types of pollution components. The first is solid, insoluble contamination, which requires a wetting agent, such as fog, and is associated with desert, coastal and Petition 870250079643, dated 05 / 09 / 2025, page 19 / 43 / 16 industrial. The second component consists of the deposition of electrolytic liquids on the insulator, which are naturally conductive and can be related to chemical mist, agricultural pesticides and acid rain.

[004] In both cases the deposited layer is conductive or can become conductive once it is wet, meaning both can result in leakage current. Furthermore, the presence of dry and wet areas on the insulator surface creates a redistribution of the applied voltage, which can cause air breakdown and create arcs on the surface that frequently culminate in flashovers.

[005] In addition to leakage current, another important effect of pollution is the decrease in the voltage gradient required for flashover to occur. With increasing pollution density, the electrical breakdown voltage decreases significantly, making insulators more vulnerable to failure.

[006] Thus, pollution not only compromises the immediate functionality of insulators, but also reduces their lifespan by accelerating degradation processes and increasing the frequency of system failures. These effects highlight the importance of effective maintenance strategies, such as the application of protective coatings and periodic cleaning of insulators, to minimize the impacts of pollution and ensure the reliability of the lines.

[007] Despite technological advances, significant gaps remain in the understanding of the regional effects of pollution on insulators. Studies have shown that the types of pollutants and their interactions with insulators vary widely depending on factors such as climate, geographic location, and nearby industrial activities, Table 1.

[008] These variations affect not only electrical performance, but also methods of monitoring and measuring pollution severity, Petition 870250079643, dated 05 / 09 / 2025, p. 20 / 43 / 16, which often did not adequately capture the complexity of the real environment. Pollutant Source Salts Coastal areas and industries Cement Cement factories, construction sites, and quarries Fertilizers Fertilizer factories and plantations Coal Coal mines and power plants Excrement Bird droppings Chemical compounds Chemical industries Smog Polluted areas Table 1

[009] To address this issue, various measurement and monitoring techniques, such as leakage current sensors and tests in controlled environments, have been employed. Document CN219842538, for example, describes a leakage current monitoring device in insulators, with the aim of improving the safety and efficiency of ultra-high voltage (UHV) transmission lines. However, this is a solution aimed at the power transmission segment, whose operating conditions and technical requirements differ significantly from the distribution segment, the focus of application of the present invention. Furthermore, the device in the aforementioned document uses semicircular shells coupled to the insulator for data collection, which contrasts with the present invention, which integrates directly into the standard insulator already present in the distribution operating environment, without the need for structural modifications.Thus, although it addresses leakage current monitoring, document CN219842538 does not cover the particularities or specific requirements of the electrical power distribution network addressed by the present invention. Petition 870250079643, dated 05 / 09 / 2025, p. 21 / 43 / 16

[010] In turn, document CN113295700 describes a method and system for monitoring the external insulation status of transmission lines, aiming to improve the safety and efficiency of power operations. However, this is a solution geared towards the transmission segment, whose operational demands and cost criteria differ significantly from the distribution segment, which is the focus of the present invention. Furthermore, the described system uses intelligent video analysis integrated with the collection of leakage current data and meteorological variables, resulting in greater complexity and implementation cost. In contrast, the invention proposes a simplified solution, based exclusively on leakage current measurement, dispensing with the use of video systems and artificial intelligence applied to the image.This approach allows for the construction of a more accessible and economically viable device for large-scale application in the electrical power distribution network, meeting its operational specificities and budgetary constraints.

[011] Document JPH11312422 describes a system for monitoring pollution in high-voltage insulators, aiming to prevent flashover failures. However, this is a solution applied to the power transmission segment, whose operating conditions and technical requirements differ from the distribution segment, the focus of the present invention. Furthermore, the described system performs harmonic component analysis of the leakage current to determine the pollution state of the insulators, a conceptually distinct approach from that adopted by the invention. The present solution is based on the direct measurement of the leakage current and the calculation of the insulator's surface resistivity, which allows for a practical and objective assessment of the contamination state, with less complexity and greater adherence to the needs and constraints of the electrical distribution network. Petition 870250079643, dated 05 / 09 / 2025, page 22 / 43 / 16

[012] In this context, the present invention aims to offer an effective solution to improve maintenance and asset management strategies, promoting greater reliability in the energy distribution segment and reducing operating costs.For this purpose, a device for monitoring saline pollution in electrical insulators by measuring leakage current and calculating surface resistivity is described here, comprising: steel tubular profiles, positioned parallel to each other; insulators positioned parallel to each other and located between the steel tubular profiles; fastening elements (60) for electrical network poles; and a housing (70) for protecting electronic components; the device also comprises a main circuit board for measurement, amplification and control; DC-DC and ADC converters; flash memory for system parameters; data storage on a microSD memory card; RTC module; leakage current sensor; temperature and humidity sensor; an LED signaling tower (20); WIFI communication; and an interface for accessing the equipment data.

[013] The present invention is geared towards application in the electrical power distribution segment in coastal regions, where assets are constantly exposed to the effects of sea spray and other corrosive agents present in the coastal environment. Unlike the transmission sector, where insulators are located in higher structures and further from the ground, distribution assets, generally installed between 12 and 14 meters high, are close to the ground and often directly facing the sea, being subjected to intense and continuous saline deposition. Considering this more aggressive operational scenario and the high number of assets involved in the distribution network, the invention proposes a streamlined and efficient device with embedded computational intelligence capable of correlating the surface resistivity of the insulator to the degree of local pollution. With this approach, it is possible to continuously monitor the Petition 870250079643, dated 05 / 09 / 2025, page 23 / 43 / 16 pollution levels, classified as light or heavy, and guide the preventive washing of insulators, contributing to the reduction of failures in the electrical system with technical and economic viability appropriate to the reality of distribution. BRIEF DESCRIPTION OF THE FIGURES

[014] Figure 1A is a graph representing the total leakage current (IaTT) as a function of voltage for three different samples.

[015] Figure 1B is a graph representing the volumetric leakage current (IaVOL) as a function of voltage for three different samples.

[016] Figure 1C is a graph representing the surface leakage current (IaSUP) as a function of voltage for three different samples.

[017] Figure 2A is a graph representing the calibration curve for current measurement.

[018] Figure 2B is a graph representing the pollution leakage stream calibration curve for constant humidity and variable temperature.

[019] Figure 2C is a graph representing the pollution leakage stream calibration curve for constant temperature and variable humidity.

[020] Figure 2D is a graph representing the leakage current measurement curve in relation to the appearance of flashover in the analyzed period window.

[021] Figure 3 shows the monitoring and control interface of the equipment.

[022] Figure 4A shows the device of the present invention.

[023] Figure 4B shows the device of the present invention with the housing cover removed. Petition 870250079643, dated 05 / 09 / 2025, page 24 / 43 / 16

[024] Figure 5A shows the device of the present invention applied in an installation station.

[025] Figure 5B shows the device of the present invention applied in another installation station. DETAILED DESCRIPTION OF THE INVENTION

[026] The following detailed description refers to the figures in which the present invention is represented, by way of non-limiting illustration. The device (100) is described in such a way as to allow a person skilled in the art to reproduce its results. Other embodiments are possible and can be carried out without departing from the concept and scope of the present invention. The following detailed description should therefore not be understood in a restrictive or limiting manner.

[027] One of the main highlights of the device (100) for measuring surface resistivity for power insulators is the presence of computational intelligence, e.g. a microcontroller system, embedded in a circuit capable of supplying an insulator (10) with voltages on the order of hundreds of volts and measuring the leakage current induced in it with intensities up to uA. In addition, the device (100) achieves adjustable power supply for switching between a photovoltaic (PV) panel and direct connection to the low voltage (LV) grid and, two-stage light indication corresponding to pollution levels (e.g., green - clean / light; red - heavy).

[028] To develop the correlation methodology between pollution severity and surface resistivity measurement, U120 glass disc insulators (10) were used as a reference. This type of insulator (10) was chosen based on the specifications established by the ABNT IEC 60815-1 standard, allowing the experimental resistivity data to be based on a recognized standard, ensuring reliability in the expected correlations. Petition 870250079643, dated 05 / 09 / 2025, page 25 / 43 / 16

[029] The essential parameters for determining the surface resistivity of the insulator (ps) are directly related to its dimensions, since the creepage distance is a fundamental component in the calculation, as demonstrated in Equation 1. OS = ------“““ΤΓ^--ΪΤPs ln^+ln^+Arsup rinfr2(1) Where: Rsé is the surface resistance obtained through the relationship between voltage and surface leakage current of the insulator; r2 is the larger radius of the glass material (radius of the first skirt); rsuper the average radius of the bell; rimph is the average radius of the pin; dei is the lower flow distance; h is the height of the first skirt.

[030] The dimensions of the U120 insulator (10), applied in the experiments, are presented in Table 2 below, which represents the dimensional parameters of the U120 glass disc insulator (10) used in the experiments. Parameter r rsup riNF dei h Dimension [mm] 127.5 40 8 247 22 Table 2

[031] The surface resistance of the U120 glass insulator (10) was determined by means of laboratory experiments, which consisted of applying DC potential and measuring the leakage current. Three samples (a1, a2 and a3) were tested in a hermetic environment to avoid variations in humidity and temperature and to ensure stability in the measurements. Petition 870250079643, dated 05 / 09 / 2025, page 26 / 43 / 16

[032] The data obtained showed a linear relationship between the total leakage current and the applied voltage, a characteristic expected for resistive loads, as shown in Figure 1a. Due to the geometry of the insulator (10), the volumetric leakage current, represented in Figure 1b, was isolated using a metal ring fixed to the upper face of the device (100), allowing the surface current to be diverted to the circuit reference. Then, the surface current was obtained by subtracting the volumetric current from the total current, as shown in Figure 1c.

[033] The analysis revealed that the volumetric currents correspond to 28%, 49% and 26% of the total current for samples a1, a2 and a3, respectively. The surface resistance was calculated based on the surface current data, from which the resistivities were determined, as shown in Table 3 below, which represents surface resistivity data for the three samples of U120 glass disc insulators (10). pa1SUP [Ω] pa2SUP [Ω] pa3SUP [Ω] 3.23-1011 10.09-1011 4.14-1011 Table 3

[034] This methodology was integrated into the system's computational intelligence, allowing the severity of pollution to be correlated with surface resistivity and the sensor's light indication to be implemented.

[035] With regard to the measurement calibration curves, Figure 2a, these refer to the expected current measurement and the acquisition system current measurement. These curves are essential for determining the accuracy and sensitivity of the system for a correct measurement of the leakage current phenomenon.

[036] With regard to pollution calibration curves, these refer to leakage current curves as a function of temperature and humidity for light and heavy pollution levels. These curves are Petition 870250079643, dated 05 / 09 / 2025, page 27 / 43 / 16 essential to determine the correlation between the leakage current of the reference insulator and the severity of pollution and, therefore, create the luminous indication.

[037] Given the application of the meter in coastal regions, the experiments were carried out using artificial saline pollution, composed of diatomaceous earth and silicon dioxide (SiO2) as non-soluble components, and NaCl as a soluble component. Diatomaceous earth was selected for its high capacity to absorb water molecules, while SiO2 was incorporated to increase the adhesion of the pollution layer to the surface of the insulators.

[038] The severity of the pollution was adjusted by varying the concentration of NaCl in the mixture, as shown in Table 4, which represents the concentrations of the components used to produce the artificial pollution solutions in 500g of deionized water. The higher the salt concentration, the greater the electrical conductivity of the pollutant layer, simulating more severe environmental conditions characteristic of coastal regions. Pollution Level Diatomaceous Earth [g] SiO2 [g] NaCl [g] Light 50 5 - Heavy 50 5 12.5 Table 4

[039] The pollution layer was applied using an air blasting system with controlled pressure of 60 psi. To ensure layer uniformity, the insulator was rotated at a constant speed of 10 rpm. After deposition, the insulator was left to dry for a period of four hours under ambient conditions.

[040] The experimental setup used to define the surface resistivity measurement methodology was replicated in a Petition 870250079643, dated 05 / 09 / 2025, page 28 / 43 / 16 climatic chamber for temperature and humidity control. Leakage current measurements were performed under two conditions: variable humidity (35%RH - 98%RH) with a constant temperature of 23°C and constant humidity of 75% RH with a variable temperature in the range of 10°C and 50°C.

[041] The graphs in Figures 2b and 2c show the calibration curves for different environmental conditions, highlighting the influence of temperature and relative humidity on the leakage current measured in insulators. Figure 2b shows the variation of the current as a function of temperature, keeping the humidity constant at 75% RH, while Figure 2c shows the current as a function of humidity, with the temperature fixed at 23 °C.

[042] In Figure 2b, it can be observed that the leakage current increases with increasing temperature, especially under severe pollution conditions. This behavior is consistent with the greater ionic mobility provided by the increase in temperature, which reduces the surface resistivity of the pollution layer. In contrast, clean insulators or those with light pollution show less variation in current values, indicating that the effect of temperature is more pronounced in highly conductive layers.

[043] In Figure 2c, the leakage current also increases significantly with increasing relative humidity, particularly for insulators under heavy pollution conditions. This result highlights the ability of the pollution layer to retain more moisture in humid environments, increasing its electrical conductivity. For clean insulators, the impact of moisture is minimal, reflecting their low interaction with water and the maintenance of high resistivity.

[044] These results highlight the strong influence of environmental conditions on the severity of pollution in insulators, particularly in high humidity or high temperature scenarios. Calibration curves Petition 870250079643, dated 05 / 09 / 2025, page 29 / 43 / 16 presented provides important subsidies for adjustments in leakage current measurements, allowing greater precision in classifying pollution conditions and in defining preventive maintenance strategies.

[045] The correlation between the leakage current of the reference insulator and the severity of pollution, with an understanding of the pollution calibration curves, allows the determination of the need for flushing, through parallel measurement, in the same environment, of the leakage current measured in the equipment outside the distribution line and the beginning of the appearance of the flashover phenomenon in insulators on the distribution line. With this correlation, it is then possible to create a luminous indication through a trend algorithm in firmware for pollution determination.

[046] The device (100) of the present invention integrates electronic instrumentation (30), dedicated firmware and a robust mechanical structure to ensure the measurement of the surface resistivity of power insulators. The instrumentation block was divided into four printed circuit boards (PCBs): main board, AC-DC conversion source, humidity and temperature sensor, and signaling tower control driver (20). The main board contains the CCCC input voltage conversion circuit, a high-precision amplifier, which converts the input current into voltage signals processed by a microcontroller (40), which operates with a 12-bit ADC converter, real-time counting module (RTC), WiFi communication module, and microSD storage module. For powering the reference insulator, a DC-DC converter controlled by PWM (Pulse Width Modulation) signals was employed, adjusted to provide 500V.

[047] The device firmware (100) was developed to collect total leakage current measurements, calculate resistivity and determine the insulator condition through trend analysis, providing an indication of the severity of environmental pollution by means of a light signal. Petition 870250079643, dated 05 / 09 / 2025, page 30 / 43 / 16

[048] To ensure energy efficiency, the system incorporates a low-power RTC module capable of maintaining date and time count even during battery power interruptions (50). This functionality allows for scheduling measurements at specific intervals every 10 minutes, taking into account daily variations in resistivity, and data storage for up to three months in microSD memory. In addition, static system parameters, such as date / time, pollution condition activation threshold, and network settings, are recorded in flash memory. In case of unexpected sensor shutdowns, the system recovers these system parameters, ensuring the resumption of operations and providing information for future analysis.

[049] Leakage current measurement, directly influenced by environmental conditions such as temperature and relative humidity, such as, for example, the SHT20 type, which communicates with the firmware via an interface, for example, I2C. A pre-flashover capture threshold is applied for classification of the need for flushing and a LOWESS peak counting and averaging algorithm is used for trend analysis.

[050] The algorithm then compares the adjusted values ​​to the environmental conditions to classify the severity of the pollution.

[051] The measurement system uses an ADC converter that operates between 0 and 4096 and in an optimized range above the raw resolution value of 372 to avoid signal saturation. Based on the ADC data, combined with temperature and humidity measurements, the firmware calculates the surface current and classifies the pollution zones, ensuring an accurate and reliable diagnosis of the insulator's condition.

[052] In turn, the mechanical structure was designed with SAE 1020 steel tubular profiles, ensuring rigidity and corrosion resistance, as well as housing the sensors, the electrical panel and the signaling tower (20) in a way Petition 870250079643, dated 05 / 09 / 2025, page 31 / 43 / 16 modular. The structure includes fixing elements (60) for poles and adaptations to protect the humidity and temperature sensor against weather. The power supply system can operate in isolation from the grid, using a 60 W photovoltaic panel, or be connected to the low voltage electrical grid, offering operational flexibility and reliability.

[053] The first validation performed focused on the leakage current simulation functionality, which corresponds to the current ranges defined by the thresholds shown in Figure 2d. For this experiment, the reference insulator was replaced by megohmmeters with resistances of 10 GΩ, 1 GΩ, 100 MΩ, and 10 MΩ. Then, a voltage of 500 V was applied across the megohmmeters, allowing the evaluation of the system's behavior in relation to the different current ranges.

[054] Figure 3a shows the interface for capturing and monitoring via web access with a local connection to the equipment through WiFi communication. It displays leakage current values, applied voltage, humidity and temperature, and LED signaling status. The interface also allows for new manual captures and downloading data stored on the microSD card. The configuration page allows for changing parameters related to network configuration, flashover threshold values, date and time, deleting stored data, and restarting the equipment. It is a complete interface for monitoring and controlling the asset.

[055] Figure 4a and Figure 4b show the structural arrangement of the device (100). In them it is possible to visualize the metal structure used to house the adopted electrical panel, for example, of the IP65 type, the reference insulator and two extra insulators used to monitor the composition of the pollution deposited on them.

[056] In addition, Figure 5a and Figure 5b show the positioning of the device (100) at two different points. As can be seen, the Petition 870250079643, dated 05 / 09 / 2025, page 32 / 43 / 16 device (100) in figure 5a is powered by a photovoltaic panel and was installed on a pole isolated from the electricity distribution network, while device (100) in figure 5b is powered by low voltage and was connected to the low voltage network.

[057] After three months of field operation, the following findings were made: the watertightness of the electrical panel was maintained, guaranteeing protection against moisture and rain; the electronic instrumentation (30) remained intact, without compromise; the luminous signaling functioned as programmed by the RTC; the sensor powered by the low voltage network remained in operation throughout the test period, presenting leakage current measurements and surface resistivity log with storage of the dates and times when the measurements were performed.

[058] The development and implementation of the device (100) of the present invention demonstrated its effectiveness in detecting and monitoring the severity of pollution in distribution network insulators. Laboratory tests validated the accuracy of leakage current measurements, surface resistivity calculation and trend analysis functionality, confirming the expected performance for signaling activation.

[059] Field experiments, carried out in real-world scenarios with prototypes equipped with different power supply systems (photovoltaic panel and low-voltage grid), aimed to validate the operational flexibility required for the sensor.

[060] Thus, it is considered that a solution has been achieved that allows the desired functionalities to be obtained efficiently and accurately. The present invention integrates sensors, embedded processing and a light indication system, solving the technical problem of measuring the surface resistivity of insulators and correlating it to environmental conditions. The present invention allows for more precise monitoring. Petition 870250079643, dated 05 / 09 / 2025, page 33 / 43 / 16 reliable pollution control in electrical insulators, facilitating the detection of contaminants and enabling predictive maintenance. Thus, the invention presented achieves the technical objectives, promoting an advance in the reliability of electrical networks and in the reduction of operational failures, overcoming the limitations of known solutions.

[061] The examples provided here are for illustrative purposes only and should not be considered as limiting the scope of the present invention. Various variations, modifications and alternative implementations may be made without departing from the spirit of the present invention. The described features may be combined in different ways or implemented using equivalent technologies and tools, provided that they maintain the described functions and purposes. Petition 870250079643, dated 05 / 09 / 2025, pages 34 / 43

Claims

1 / 2 CLAIMS 1. Device (100) for monitoring saline pollution in electrical insulators by measuring leakage current and calculating surface resistivity, characterized in that it comprises: tubular steel profiles, positioned parallel to each other; at least one insulator (10) located between the tubular steel profiles; fastening elements (60) for electrical network poles; a housing (70) for protecting electronic components; a main circuit board for measurement, amplification and control; DC-DC and ADC converters; flash memory for storing system parameters; microSD memory card for recording operational data; real-time clock module; leakage current sensor and temperature and humidity sensor; WiFi communication module; monitoring and control interface; luminous signaling tower (20) indicating pollution levels;and embedded firmware configured to calculate the surface resistivity of the insulator and classify the pollution level. Petition 870250079643, dated 05 / 09 / 2025, page 35 / 43 2 / 2; 2. Device (100), according to claim 1, characterized in that it comprises a power supply from a low voltage source.

3. Device (100), according to claim 1, characterized in that it comprises a power supply from a photovoltaic panel.

4. Device (100), according to any one of claims 1 to 3, characterized in that the calculation of surface resistivity is used to determine the flashover appearance threshold, for the analysis of the need for washing.

5. Device (100), according to any one of claims 1 to 4, characterized by comprising the identification of surface resistivity peaks in a period window of days together with the calculation of the LOWESS average to determine the trend and signaling of pollution requiring washing implemented in firmware. Petition 870250079643, dated 05 / 09 / 2025, pp. 36 / 43

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