Leakage Current on Porcelain and Silicone Insulators Under Sea or Light Industrial Pollution (original) (raw)
Related papers
Comparison of pollution level of aged porcelain and silicon rubber insulators
2015 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP), 2015
In this paper, an artificial neural network (ANN) has been used to compare the pollution level of aging long-rod silicon rubber and porcelain insulators. High regression values and effective correlation of equivalent salt deposit density (ESDD) have been found using MATLAB neural network toolbox. It has been found that the bottom surface of the porcelain insulator contains more pollution than the top surface. Higher pollution has also been measured in case of silicon rubber (SiR) insulator. Pollution levels in case of both insulators have been found to be exceptionally high compared to IEEE and CIGRE standards.
Leakage current analysis of polymeric insulators under uniform and non‐uniform pollution conditions
IET Generation, Transmission & Distribution, 2017
This study presents two different methods under uniform and non-uniform pollution layer in order to measure and calculate the leakage current (LC) of silicone rubber insulators. Experimental test for evaluating the LC analysis of polluted insulator have been done in a laboratory clean fog chamber. The electric field and potential distributions were obtained from finite element method software for 3D models. The mathematical background and circuit theory are described in details by a section of insulator and using the extended form factor formula. The surface conductivity used in the calculations was extracted from the measured LC after wetting rate. LC characteristics under 1 : 1, 1 : 2, 1 : 5 and 1 : 10 ratios of top to bottom surface salt deposit density on polymeric insulators are studied. To verify the proposed models of this study, the results of experimental data and two other approaches are compared with together before dry-band formation. Moreover, a dynamic LC model under uniform pollution layer has been introduced and extended in order to calculate the LC when the formation of dry-bands along the insulator surface occurs. The dynamic model is drawn from experimental data and measured surface conductivity.
Dielectric behaviour of polluted porcelain insulators
IEE Proceedings - Generation, Transmission and Distribution, 2001
The dielectric behaviour of polluted porcelain insulators is investigated by means of experimental tests and simulation methods. The elaboration of the experimental results, using well known mathematical models of polluted insulators, leads to the identification of the arc constants. It was found out that the arc constants are independent of the insulator type and of the experimental pollution procedure (salt fog or solid layer cool fog method). This allows the formulation of a generalised simulation model of polluted insulators. The critical parameters for the flashover (voltage, current and gradient) are computed by means of the developed model, using only the geometric dimensions of the insulator, the pollution severity and the arc constants. Different types of porcelain insulators are investigated and the variation of the critical parameters upon the density of the pollution layer is determined. The influence of the geometrical dimensions and of the shape of the insulator to the critical parameters is also investigated. Furthermore, analytical relations are defined, between the computed critical parameters and the salt deposit density as well as the dimensions, the shape and the type of the insulator.
PERFORMANCE ANALYSIS OF OVERHEAD PORCELAIN INSULATOR UNDER DIFFERENT CONTAMINATIONS
Overhead insulators play an important role in electrical transmission network. When insulators is subjected to operation in open environment their insulation strength decreases. Mixture of pollutants in addition with the humidity forms a layer on the surface which increases conductivity that leads to the flow of leakage current leading to flashover. Artificial test is conducted in the laboratory as per the standard to analysis the performance of insulator. In this analysis an 11 kV porcelain insulator is subjected to power frequency test under different pollution condition. It is clear from the experiments done on the insulators that flashover occurs at lesser voltages when the pollution level is high which in turn increases conductivity.
International Journal on Electrical Engineering and Informatics, 2018
Insulator is one of the most important equipment in an electric power system. Failure of insulator may interrupt the electric energy delivery. The system reliability is greatly affected by the performance of the insulator. Therefore, ensuring the high performance of insulators has become indispensable. There are many methods to increase the performance of the outdoor insulator that are exposed to environmental conditions, such as temperature, humidity, and the presence of pollutants. Among the methods, applying room temperature vulcanized (RTV) silicone rubber coating and semiconducting glaze on the insulator surface are often used. This paper discusses the performance of uncoated ceramic insulator, RTV silicone rubber coated insulator, and semiconducting glazed insulator (SGI), as well as the comparison result among them. The performance is indicated by measuring leakage current (LC), surface temperature, and hydrophobicity. In addition, computer simulation on outdoor insulators using ATPDraw software is also conducted for LC waveform resulted by each type of insulator in order to study the electrical properties of each insulator. In the simulation, an outdoor insulator is represented by an electrical circuit model consisting of capacitors, nonlinear resistors, and number of arc models. AC voltage is applied to the model and the current is monitored. Hence, some key parameters of LC waveform are required to determine the similarity between measured LC waveform and simulated LC waveform, which are LC magnitude, Total Harmonic Distortion (THD), and dominant harmonic number. Experiment result shows that LC waveform and magnitude are strongly affected by the applied voltage, environmental condition, and the condition of the insulator surface itself. Specifically for SGI, LC waveforms are generally similar with the sinusoidal applied voltage. The LC waveforms are also symmetrical for positive and negative half cycles and no flashover was observed for applied voltage up to 40 kV. The hydrophobicity of insulator surface decreases after the experiments, with the pollutant presence and salt fog condition cause higher reduction compared to the clean samples and in clean fog environment. SGI has higher hydrophobicity compared to ceramic insulator. Field-aged RTV silicone rubber coated insulator shows higher hydrophobicity compared to field-aged uncoated ceramic insulator. At the end of the 6 th year, the difference of contact angle between the two types of insulators can reach up to 50-60°. This proves that less pollutant is likely to stick on coated insulators for long time. The LC waveforms obtained from all experiments both in the laboratory or in the field have been successfully simulated through computer simulation. The simulation indicated that SGI is more capacitive than normal ceramic insulator and has lower values of piecewise resistance of the nonlinear resistance, resulting LC flow on the insulator surface also much higher. Despite the increased applied voltage, SGI shows very little discharge on its LC waveform, hence it has only 2 arc models, while at higher applied voltage, ceramic insulator has many discharges occur along the LC waveform, hence the arc models for this insulator can reach up to 9 arc models.
A negligible percentage of the cost of a Power Generation Plant or Transmission network goes towards the cost of insulators, yet the cumulative O&M costs, outage costs and equipment damage costs due to poor insulator performance can be staggering. Entire transmission grids have been known to collapse due to a pollution flashover on a single insulator. Common practices to try and attain uninterrupted performance of outdoor porcelain and glass insulators include live-line Insulator washing, application of silicone grease, specially designed ‘anti-fog insulators’, contamination source reduction and increased maintenance surveillance. These methods often fail to prevent failures and are at best temporary solutions. One of the methods adopted to eliminate pollution flashovers is the use of RTV Silicone Insulator Coatings. Widespread field experience suggests this could be one of the most promising methods to eliminate flashovers, even in the harshest environments. This paper reviews field experiences of gen-4 RTV Silicone HV Insulator Coatings (HVICs) in very heavily polluted environments and how they have had an exceptional success rate in eliminating flashovers, even when all other methods have failed.
Ageing of silicone rubber insulators in coastal and inland tropical environment
IEEE Transactions on Dielectrics and Electrical Insulation, 2000
This paper presents investigations on the performance of 33 kV silicone rubber insulators characterized by different creepage lengths, which aimed to find out whether the insulators could permanently work when electrically stressed beyond the recommended limits in polluted and clean tropical environments. The study was performed under natural field and laboratory conditions. The insulators tested included eight types of silicone rubber composite insulators, one type of hybrid siliconeceramic insulator and one semi-conducting glazed porcelain insulator, while ordinary porcelain and glass insulators were used as reference. During the field investigation, two sets of the insulators were separately installed and energized in coastal and inland parts of Sri Lanka, being by that exposed to marine and clean tropical environments. Their performances were periodically evaluated by visual inspections and measurements of hydrophobicity class. After five years of field exposure, the insulator performances were evaluated in laboratory by measurements of leakage currents under clean fog conditions and of wet flashover voltage. A third set of the insulators was aged in laboratory for 1000 hours inside a salt fog chamber where the insulators were continuously energized and daily sprayed with salt solution for eight hours and left to rest for remaining 16 hours. This treatment represented conditions similar as those in the field i.e. insulators exposed to salt sprays during monsoons. The insulator performances were investigated by measurements of leakage currents and classifying their patterns into different categories, i.e. capacitive, resistive, non-linear, discharge and strong discharge types, by means of fast Fourier transform and short time Fourier transform analyses. It was found that the long-term field exposure yielded weaker insulator deterioration than the salt fog chamber ageing, which indicated for a possibility to increase the electric stress on silicone rubber insulators to levels higher than the ones used today on glass and porcelain counterparts.
DYNA
Este documento presenta un modelo útil para determinar los períodos de lavado e indicar los niveles de contaminación de aisladores eléctricos. El comportamiento de la corriente de fuga, como indicador de la presencia de contaminantes en las superficies de los aisladores, se caracterizó a través de un modelo de regresión. Se examina cuantitativamente el comportamiento de la corriente de fuga y la contaminación de los componentes eléctricos. Se analizan los datos de las variables ambientales y la corriente de fuga en una subestación eléctrica y se identifica un modelo que representa bien el comportamiento de la corriente de fuga en los aisladores. Con este modelo, se pueden realizar predicciones del efecto de contaminación utilizando herramientas de análisis para identificar los efectos de la corriente de fuga en toda la red. Este método se puede usar para obtener modelos de corriente de fuga en subestaciones eléctricas ubicadas en zonas altamente contaminadas.
Performance of Ceramic Insulator Type under Different Polluted Conditions
this paper investigates the distributions of the electric field and the potential along one ceramic unit insulator under different polluted conditions. Modeling results are obtained using software depends on the finite integral method (FIM) to solve the partial differential equations that describe the behavior of electric field. To investigate the influence of the pollution on the electric field and voltage distributions on the insulator surface, the units are covered with a thin film of a pollutant layer. Finally the results referring to clean insulators have been compared with those referring to polluted insulators under various conditions.
Scientific Reports
The monitoring of leakage current (LC) and voltage characteristics in transmission line insulators is regarded as a good technique for anticipating the physical state of in-service insulators. In the current work, the temporal and frequency characteristics of LC and voltage under various situations were derived for assessing the health condition of porcelain, glass, and silicone rubber insulators. The contamination severity indicated by soluble deposit density, wetting level (Wt), non-soluble deposit density, and uneven pollution distribution (Pu/PL) were chosen as the environmental factors that impact the insulators. Six criteria were utilized to evaluate the physical state of the insulators, with four of those derived from the LC signal in the time domain, namely, the LC signal peak (C1), the phase shift between applied voltage and LC (C2), the LC signal slope between two consecutive peaks (C3), and the crest factor (C4). The remaining two indices, namely, the total harmonics dist...