Value Of Flashover Voltage Research Articles

Modeling and simulation for flashover location determination on 150 kV insulator string

The 150 kV Payakumbuh-Koto Panjang transmission line in West Sumatra is located in an area with high lightning activity. Based on Meteorological, Climatological, and Geophysical Agency (BMKG) data (2017-2023), the average number of lightning days per year (IKL: isokeraunic level) reaches 165-173 days/year, and 79% of the transmission towers are located in hilly and rocky areas. This causes contamination of the insulator, which can reduce its performance and cause flashovers in the insulator circuit. However, in the field, finding flash points in insulators is still a challenge. Therefore, simulation must be used as a tool to determine the location of flashover in an insulator circuit that is affected by temperature and humidity. Simulation by modeling flashover provides an effective solution for determining the location of flashover in insulator circuits, which is the novelty of this research. This research compares laboratory test results with manual calculations modeled using Visual Basic 6. The research results show that temperature and humidity have a significant influence on determining the flashover voltage value on the insulator. The flashover locations during the test are the same as the calculated flashover locations, as shown by these simulations and modeling.

The Effect of Humidity and Temperature on Flashover in High Voltage Transmission Line Ceramic Insulators

This research aims to determine the flashover voltage on the surface of porcelain insulators on 150 kV transmission lines located in Payakumbuh, where the insulators are contaminated with dust and moss due to the effects of temperature and humidity. The experiment is carried out with only up to seven insulator plates due to the limitations of the available apparatus. For the further testing, a trend analysis is applied. According to the experimental results, a rise in temperature around the insulator will increase the flashover voltage value and accelerate the potential for a flashover event. This happens because high temperatures can reduce the insulator's dielectric strength and insulation resistance and increase the risk of flashover. The dielectric strength values decreased with an average decrease of 44.62% per insulator plate for dusty insulators and 45.08% for each plate for mossy insulators. The results aim to minimize flashover on transmission lines in hilly areas with relatively high contamination.

Assessment of the Effect the Height and Relative Position of Support Insulation Components Have on the Insulation Electrical Strength

The article presents the results from studies of the effect the height and relative position of extra high voltage class support insulation components have on the insulation electrical strength when subjected to positive polarity switching impulses, at which the insulation minimum permissible overall dimensions are determined. It is shown that the highest values of the insulation flashover voltage are achieved when a leader discharge develops along purely air trajectories: screen--pedestal or screen-- plane. A similar result is obtained in the case of cascade flashovers from the screen over the column elements if the upper insulator structural height is significantly larger than that of the lower one. The reverse mutual arrangement of these insulators leads to a significant drop in the insulation flashover voltage during cascade flashovers. It is shown that at the final jump onset moment, the main contribution to the insulation flashover voltage value is introduced by the voltage drop across positive streamers, which is directly proportional to the length of these streamers. Hence it follows that the ambiguous effect of the height and mutual arrangement of the support insulation components on the insulation electrical strength during cascade flashovers is mainly due a significant difference in the lengths of the positive streamer zones at the final jump onset. With the upper insulator height equal to 2.7 m, the length of positive streamers at this moment is commensurable with the length of streamers when the flashover develops along purely air trajectories, whereas decreasing the upper insulator height by almost a half entails a significant decrease in the streamer lengths. Measures to eliminate undesirable cascade flashovers and ensure the highest electrical strength of support insulation are proposed.

Alumina Trihydrate Effect on Flashover Voltage of Polyester Insulators by Whale Optimization Algorithm Technique

Ceramic materials are commonly used as outdoor insulators for high-voltage power transmission lines. Presently, these ceramic insulators are replaced by composite polymeric insulators with polyester, especially in rainy areas. Unlike ceramic materials, polymer materials have a shorter life, so fillers are used to improve their physical and chemical properties. This paper aims to improve the flashover voltage performance of polyester loaded with Alumina Trihydrate filler in wet weather condition. Due to the high cost of raw materials (polyester and Alumina Trihydrate filler), the Whale Optimization Algorithm model was used to predict the best concentration of Alumina Trihydrate filler to give the best value of flashover voltage. The model is based on experimental data of flashover voltage measurements. A positive correlation of the calculations from the Whale Optimization Algorithm model with experimental data has been demonstrated. The results showed that the flashover voltage performance of polyester is increased with the increase of Alumina Trihydrate filler concentration. Also, the optimum concentration of Alumina Trihydrate filler and flashover values predicted by the MATLAB Whale Optimization Algorithm are very accurate.

EXPERIMENTAL DETERMINATION OF FLASHOVER PERFORMANCE OF CYLINDRICAL SPACERS IN N2:SF6 GAS MIXTURE UNDER AC VOLTAGES FOR NON-UNIFORM FIELDS

The gas mixture N2:SF6 has been used in gas insulated switchgears, gas insulated transmission lines and gas insulated cables for years in order to reduce the use of SF6 gas in electrical system. By taking into account the insulation performance and environmental effect, it is advised that the use of N2:SF6 gas mixture in practical to lower the SF6 gas content as far as possible. The present study is undertaken using different N2:SF6 gas mixture ratio to determine the flashover characteristics under AC voltages. In this paper the effect of floating particles, use of different insulating spacers namely PMMA, PP and NYLON and their combination forms hybrid spacers has been studied in non-uniform electric field (needle – plane) electrode configuration. The surface flashover performances of individual and hybrid spacers have been compared in N2:SF6 gas mixture. The experimental results shows that conventional spacer PMMA show better performance than the other spacers (PP and NYLON) at the gas pressure of 0.18MPa. As the gas pressure increases further the flashover voltage values slightly decreases. The hybrid spacer PMMA – PP are more effective at lower pressure than other spacer combinations. With floating particle, PP shows better flashover at lower pressure and the performance of PMMA – NYLON is much better at lower pressure.

Experimental and Estimation of Flashover Voltage of Outdoor High Voltage Insulators with Silica Filler Based on Grey Wolf Optimizer

Abstract Epoxy is used widely in high voltage outdoor insulator because of its light weight (this avoids the need to use heavy cranes for their handling and installation and this reduces cost), easy handling, easy blending with additives, and having hydrophobicity. This paper focuses on improving epoxy electrical characteristics (flashover voltage) for high voltage outdoor insulator by adding silica filler. Composite of epoxy with silica filler: silica is prepared with 0 %, 10 %, 20 %, 30 % and 40 % weight percentages concentration. The flashover voltage (FOV) is tested under various environmental conditions with different samples lengths. Grey wolf optimizer (GWO) is developed to predict the best optimal value of flashover voltage under various environmental conditions using laboratory measurements of flashover voltage. The obtained results from GWO are compared with experimental measured data. Results showed an improvement with silica concentration at different samples lengths in flashover voltage for composite samples over epoxy without any additions. A comparison between three different conditions showed higher flashover voltage for samples in dry condition than that of samples in (wet, salt wet) conditions.

An Improved Pollution Testing Methodology for Polymeric Insulators: Analysis on Surface Coating and Flashover Voltage Under Solid Layer Test

Polymeric insulators have found application worldwide in outdoor insulation system due to their better pollution performance. Since there are no standard laboratory test methods to analyse pollution performance of polymeric insulators, selection and dimensioning of proper insulator is still confusion for engineers and utilities. IEC and CIGRE working groups have recently suggested a test method for solid layer pollution testing of polymeric insulators. The uniformity of pollutant coating over hydrophobic insulator surface was not consistent with CIGRE Round Robin Test procedure. In this research work, a method of soaking the insulators in water as a part of preconditioning before actual pollutant spray was adopted and uniformity of coating was compared with CIGRE round robin test procedure. Critical analysis has been made on the loss and recovery of hydrophobicity characteristics on silicone insulators and its ability to transfer the hydrophobicity to pollution layer were observed and recorded over a period of 15 days with the proposed coating method. Solid layer pollution test was carried out on 66 kV long-rod insulators with the proposed test procedure and the results were compared with CIGRE procedure. 50% Flashover Voltage (U50%) of the insulator was determined before and after withstand test for both the test methods and standard deviation was calculated. The variation in the flashover voltage values has been calculated before and after withstand test. From the results, it’s been observed that, the hydrophobicity character was not influenced to the pollution layer in the given recovery period but the recovery time had an impact on flashover voltage. The deviations in flashover voltage value compared before and after withstand tests, found to be within 5% for both CIGRE procedure and modified test procedure.

Prediction of Flashover Voltage of High-Voltage Polluted Insulator Using Artificial Intelligence

The objective of this study is to predict the flashover voltage of a high-voltage insulator artificially contaminated using artificial intelligence (AI). First, practical tests were performed on a high-voltage insulator to collect a database used in the implementation of the artificial intelligence concept. These tests were realized for different levels of artificial pollution (saline distilled water). Each pollution level presented an amount of artificial pollution, in milliliters, in each petticoat (zone) of the insulator. The collecting database gives flashover voltage values corresponding to different amounts of artificial pollution in each insulator zone and its conductivity. Second, we have introduced fuzzy logic (FL) and artificial neural networks (ANN) as two AI techniques to predict the flashover voltage of the high-voltage insulator and to estimate the insulating state of artificial pollution. The proposed prediction concepts based on FL and ANN are implemented using MATLAB’s graphical user interface. Finally, a comparison was made between the results obtained by AI and practical ones. The database used in this comparison is different from that used in concepts based on FL and ANN implementation. The obtained results show a high efficacy of FL and ANN techniques in predicting the flashover voltage of high-voltage insulators compared with those obtained by practical tests.

Experimental investigation on pollution flashover performance of multiple parallel suspension insulators

In order to meet the requirement of mechanical properties, multiple parallel suspension insulators will be used in UHV lines. In this paper, pollution flashover performance of multiple parallel insulators has been investigated based on artificial contamination tests under both AC and DC voltage. Four types of multiple parallel suspension mode are used in the tests, which has 2 strings, 3 strings, 4 strings and 6 strings, respectively. Experimental results indicated that multiple parallel insulators’ pollution flashover voltage was lower than that of single string. Study showed that the result is not only affected by the multiple string leads to reduced pollution flashover probability, but also affected by the ionization of air. When the parallel number was less than 4, pollution flashover voltage of multiple parallel porcelain insulators was about 4% lower than that of a single string. If the parallel number was greater than or equal to 4, the value of flashover voltage was reduced by more than 10%. For composite insulators, the voltage drop of the multiple parallel insulators is not as obvious as that of porcelain insulators. In actual project application of the multiple parallel strings, the number of porcelain insulators and the insulation length of composite insulator was proposed to increase. The conclusion of this work can provide technical reference for the external insulation design and construction of UHV transmission lines.

Study the flashover voltage for outdoor polymer insulators under desert climatic conditions

This work presents a study of flashover voltage for outdoor polyester and composite insulators under some desert climatic conditions. Cylindrical polyester composite samples have been prepared after incorporated with different concentrations of inorganic fillers e.g., alumina trihydrate [ATH], boric acid [H3BO3] and magnesium hydroxide [Mg(OH)2] to improve the electrical, mechanical and thermal properties in addition to maximize the surface flashover voltage and decrease the tracking phenomena.Results showed that flashover voltage reaches to 38kV for samples without filler and 47kV for samples containing 50% of ATH filler in dry condition. A comparison between inorganic fillers under various environmental conditions showed higher flashover voltage values for samples containing ATH filler than that of samples containing H3BO3 and Mg(OH)2 fillers at all filler concentrations. Flashover voltage increases 24% by adding ATH filler for polyester samples under sandstorm conditions. Also, in this study, the effects of sandstorm, ultra violet (UV) radiation, mechanical strength (compressive and tensile strengths) and thermal performance with respect to surface of the sample under test have been investigated in detail.

Evaluation of Flashover Voltage Mechanisms on Hydrophobic Polymer Insulators with Artificial Neural Network Approach

This paper presents an experimental measurement of ac 50 Hz flashover voltage (kV) of hydrophobic polymer insulators. Hundred thirty five different testing conditions were used to evaluate the electrical performance of hydrophobic surfaces of composite polymer insulators. The study of flashover voltages depend on the silicone rubber (SiR) content (%) in Ethylene propylene diene monomer (EPDM) rubber, water conductivity (µS/cm), volume of water droplet (ml) and number of water droplets on the surface of polymer insulators. Artificial neural network (ANN) is used successfully to model nonlinear functions which are difficult to model using classical methods. ANN can estimate the values of flashover voltage (kV) for different polymer insulators. The proposed network is trained using different environmental wet condition such as; water conductivity, volume of water droplet and number of water droplets on the surfaces of composite different polymer. After training, the network can estimate the flashover voltage for different inputs. A comparison between the laboratory measurements of flashover voltages and computational results of ANN were convergent. The results obtained from applying ANN show that it can be used to model the data with accuracy of 96%. These results prove that ANN can be considered a successful model to evaluate the electrical performance of hydrophobic polymer insulators and predicts the best hydrophobic composite surface that withstands higher flashover voltage under wet contaminated weather condition.

The pollution flashover on high voltage insulators

The pollution flashover, observed on insulators used in high voltage transmission, is one of the most important problems for power transmission. It is a very complex problem due to several factors such as the modeling difficulties of complex shapes of the insulators, different pollution density at different regions, non-homogeneous pollution distribution on the insulator surface and unknown effect of humidity on the pollution. In the literature, some static and dynamic models were developed by making some assumptions and omissions to predict the flashover voltages of polluted insulators. In this study, historical development of insulator modeling was investigated and a dynamic arc model was proposed. For this purpose, scaled shape of a concerned insulator was firstly partitioned into triangular elements, then finite element method (FEM) was implemented and finally potential distribution on the insulator surface, variation of pollution resistance and flashover voltage were determined. The computed flashover voltage values of the selected string insulator have been compared to results from other research.

An empirical expression for the determination of the effects of rain on the AC flashover voltage of high voltage insulators

This paper describes the development of an empirical expression that relates the AC flashover voltage of post-type insulators to the rate of rainfall, the conductivity of the rainwater, and the angle of the rainfall with respect to the insulator position. A unique and novel method is used to develop the empirical relationship. The resulting empirical expression shows good agreement with experimental AC flashover voltage values obtained from laboratory tests.

AC and lightning performance of fiberglass crossarms aged in 115 kV transmission line

This paper presents the results of an investigation of the electrical performance of 115 kV transmission line fiberglass crossarms used by Mississippi Power and Light Company. A transmission line fiberglass crossarm removed from service and companion crossarms stored outdoors but not in service were examined. The evaluation of electrical performance was based on flashover voltage value at AC voltage and standard lightning impulse as well as under dry and wet conditions. The tests were performed in the Mississippi State University High Voltage Laboratory. The obtained flashover voltages show no large difference in electrical strength of fiberglass crossarms removed from service and those stored outdoors. The added critical flashover voltage by fiberglass crossarm to the porcelain suspension insulators is presented versus the length of the fiberglass crossarm for dry and wet conditions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Spacer Flashover in Compressed Gases

Surface flashover studies of cylindrical spacers are carried out in SF6-N2 and other SF6-gas mixtures in a uniform field. In the presence of the spacer, the value of the surface flashover voltage is typically found to be lower than the corresponding breakdown own voltage of the gas gap without the spacer. It is experimentally found that this reduction in the breakdown voltage depends to a large extent on the dielectric constant of the spacer material, the type of end-contact between the spacer and the electrode surface, the surface condition of the spacer, the content of SF6 in the gas mixture, and the gas pressure. re. From these experimental results, an empirical expression is developed for the first time to predict in compressed gases. The calculated values of the flashover voltage show a good agreement with the measured values of the author as well as with those previously published in the literature.