Rod Insulators Research Articles

Impact of increased temperature of lower end-fitting of a composite long rod insulator on its mechanical strength under variable loads

Impact of increased temperature of lower end-fitting of a composite long rod insulator on its mechanical strength under variable loads

Benchmarking Generations of You Only Look Once Architectures for Detection of Defective and Normal Long Rod Insulators

Effective infrastructure monitoring is a priority in all technical fields in this century. In high-voltage transmission networks, line inspection is one such task. Fault detection of insulators is crucial, and object detection algorithms can handle this problem. This work presents a comparison of You Only Look Once architectures. The different subtypes of the last three generations (v3, v4, and v5) are compared in terms of losses, precision, recall, and mean average precision on an open-source, augmented dataset of normal and defective insulators from the State Grid Corporation of China. The primary focus of this work is a comprehensive subtype analysis, providing a useful resource for academics and industry professionals involved in insulator detection and surveillance projects. This study aims to enhance the monitoring of insulator health and maintenance for industries relying on power grid stability. YOLOv5 subtypes are found to be the most suitable for this computer vision task, considering their mean average precision, which ranges between 98.1 and 99.0%, and a frame per second rate between 27.1 and 212.8, depending on the architecture size. While their predecessors are faster, they are less accurate. It is also discovered that, for all generations, normal-sized and large architectures generally demonstrate better accuracy. However, small architectures are noted for their significantly faster processing speeds.

Study on the Contamination Characteristics of V-Type Double Suspension Rod Insulators Based on the Influence of Wake Flow

The insulators of the catenary of the Lanzhou-Xinjiang High-speed Railway in windy areas suffer from serious contamination, which has led to frequent flashover accidents. The catenary of the Lanzhou-Xinjiang High-speed Railway has adopted the unique external insulation of V-type double suspension rod insulators. To further determine the contamination characteristics of this type of insulator, a contamination simulation model of insulator is established in this paper based on the principles of fluid mechanics, which is used to analyze the contamination characteristics of the V-type double suspension rod insulators under the influence of wake flow. The research results show that wind speed directly determines the static pressure on the surface of the insulator, the wind speed and particle concentration are proportional to the contamination volumes on the windward and crosswind sides of insulator, while the particle size is inversely proportional to the contamination volume on the leeward side of the insulator. The direction of wake flow is consistent with the direction angle of external incoming flow, and the wake flow generating area affects the contamination characteristics of the insulator. When the incoming flow is at a prevailing wind direction of 0°, focus should be put on the windward and crosswind sides of the two insulators during insulator cleaning, and the contamination distributions on these two insulators are similar; when the incoming flow is at a prevailing wind elevation of 0°∼60°, focus should be put on the entire surface of 1# insulator and the windward and crosswind sides of 2# insulator during insulator cleaning.

Comparison of natural contamination accumulation characteristics between composite rod insulators and standard suspended insulator strings

Comparison of natural contamination accumulation characteristics between composite rod insulators and standard suspended insulator strings

Use of Rod Compactors for High Voltage Overhead Power Lines Magnetic Field Mitigation

In the last decades, strengthening the high voltage transmission system through the installation of new overhead power lines has become critical, especially in highly developed areas. Present laws concerning the human exposure to electric and magnetic fields introduce constraints to be considered in both new line construction and existing systems. In the paper, a technique for passive magnetic field mitigation in areas close to overhead power lines is introduced, fully modelled and discussed through a parametric analysis. The investigated solution, which basically consists in approaching line conductors along the span making use of rod insulators, is applicable on both existing and under-design overhead lines as an alternative to other mitigating actions. Making use of a 3-dimensional representation, the procedure computes both positions of phase conductors and forces acting on insulators, towers, conductors and compactors, with the aim of evaluating the additional mechanical stress introduced by the compactors. Finally, a real case study is reported to demonstrate and quantify the benefits in terms of ground magnetic field reduction achievable by applying the proposed solution, in comparison to a traditional configuration. Furthermore, using compactors to passively reduce the magnetic field is simple to be applied, minimally invasive and quite inexpensive as regards to alternative mitigating actions.

Development of Coating Process Technique for Anti-Fouling Electric Insulator

In order to improve the anti-fouling characteristics of the electric insulator for electric railway, a functional coating for preventing pollution was carried out on the surface of the T type post insulator and long rod insulator in the railway insulators. In order to ensure the durability of the thin film on the coated insulator surface, the coating was annealed at three different annealing cases by using a furnace. Case 1 is annealing treatment at 250°C and case 2 is annealing treatment at 400°C. Case 3 is the double annealing treatment (case 1 + case 2). The film Surface conductivity and anti-fouling characteristics of the insulators annealed at three temperature conditions were measured. It was confirmed that the insulator annealed in case 3 had both good conductivity and anti-fouling characteristics.

Prediction of pollution flashover voltages of ceramic string insulators under uniform and non-uniform pollution conditions

Present paper emphasizes on the development of a new mathematical model to estimate the contamination flashover voltages of ceramic string insulators under varying uniform and non-uniform pollution conditions subjected to AC voltages. The proposed model is developed based on dimensional analysis of the factors which commonly influence the process of contamination flashover of insulators. The new model for string insulators has been validated using previous authors both experimental and analytical results for total of fifteen string insulators including porcelain, glass string insulators and one porcelain log rod insulator. The validation of the new model indicated that results of proposed model for string insulators are in good agreement with published experimental and model results.

Diagnosis of High Voltage Insulators Made of Ceramic Using Spectrophotometry

The paper presents results of comparative analysis of optical signals emitted by partial discharges occurring on three types of high voltage insulators made of porcelain. The research work consisted of diagnosis of the following devices: a long rod insulator, a cap insulator, and an insulating cylinder. For optical signal registration a spectrophotometer was applied. All measurements were performed under laboratory conditions by changing the value of partial discharges generation voltage. For the cylindrical insulator also the distance between high voltage and ground electrodes was subjected for investigation as a factor having influence on partial discharges. The main contribution which resulted from the studies is statement that application of spectrophotometer enables faster recognition of partial discharges, as compared to standard methods.

The Analysis of Frequencies of Own Insulators Fluctuations for the Solution of a Problem of their Control

Upon the diagnostics of basic rod insulators by method of free fluctuations the main difficulty is the choice of the informative frequency ranges of a spectrum characterizing existence of defects. A problem of work is the analysis of frequencies of own fluctuations of rod basic insulators. The ANSYS software package for the final element modeling was used. Numerical experiments are made.

Automatic recognition for catenary insulators of high-speed railway based on contourlet transform and Chan–Vese model

Aiming at the diversity distribution of the catenary rod insulator image, this paper proposes a new idea of detecting and recognizing the rod insulator of high-speed railway, which is based on contourlet transform (CT) along with Chan–Vese (CV) model. First, the anisotropy and directionality of the catenary rod insulator image is detected with CT in the frequency domain, which can provide a variety of texture analysis. Then, in order to find the center of textures, the digital morphology filtering and the fuzzy clustering are adopted to process the textures. Finally, the insulator boundaries, including the abundant geometry information, are detected by CV model. The experimental results show that the proposed approach can efficiently realize the automatic recognition of the rod insulators in real-life catenary images of high-speed railway, even with the insulator porcelain skirt interdigitating.

Mathematical Modeling on AC Pollution Flashover Performance of Glass and Composite Insulator

While considering the current scenario, in this world power demand goes on increases day by day. Frequent power outages occur in high voltage transmission line due to the deprived performance of polluted insulators; this affects overall operation of power system and may indirectly impinge on the growth of production sector. Many researchers are keenly taking efforts to provide highly reliable and stable power to neediest. In this paper, A.C pollution flashover performance of disc type glass insulator and composite long rod insulators investigation under various artificial pollutions by varying Equivalent Salt Density Deposition (ESDD) levels. Here, we use different types of pollution methods like binding method, dipping method and spraying methods with different types of pollutants concentration. Based on dimensional analysis, four different Mathematical models have been developed to predict the A.C pollution Flashover Voltage (FOV) of insulators. Both the experimental and mathematically modeled results are compared; it’s observed that mathematical model 3 yields better results.

Study on operating properties of ceramic long rod insulator for transmission line

The material prescription, potential distribution, contamination trend and surface insulating properties under contamination and lightning conditions for the ceramic long rod insulator are investigated. The surface contamination trend of the ceramic long rod insulator can be fitted to an exponential function in a low rainfall area. Potential distribution calculation by three-dimensional finite element method shows that over 50% operating voltage concentrates on the single unit of high-voltage polarity for the long rod insulator string, which is more uneven in comparison with the disc ceramic insulator string. Five-hundred kilovolt full-scale artificial pollution test demonstrates that the contamination flashover voltage of the ceramic long rod insulator has a negative exponential relationship with equivalent salt deposit density and a linear relation with string length. A lightning impulse discharge test confirmed that the relation between 50% lightning impulse discharge voltage and dry arcing distance was also linear for a ceramic long rod insulator string.

Evaluation on flashover voltage property of snow accreted insulators for overhead transmission lines, part II - flashover characteristics under salt contaminated snowstorm

This paper presents the flashover characteristics of snow-bridged insulators, and the related discharge propagation phenomena in the presence of salt contaminated snowstorms. Two types of flashover tests, a) Snow accretion without voltage application, then apply the voltage after snow accretion, b) Snow accretion during voltage application, were carried out on a 33 kV long rod insulator with the snow conductivity controlled between 180 and 980 μS/cm. Method a simulates the cold switch-on situations. In this case, the flashover voltage is found to be inversely proportional to the fifth root of the snow conductivity. Further, the flashover voltage showed a relation to the leakage resistance of snow-bridged insulators. Method b simulates energized situations during a snowstorm. The concept of Method b is equivalent to the “Ice Progressive Stress (IPS)” method described in the IEEE Std. 1783-2009. In this case, partial arc discharges gradually increase owing to the development of snow accretion. Flashovers are mostly induced during the period of snowstorm suspension, because the arc discharge can develop into a flashover without the cooling effect of the blizzard. Melting snow by heating of electric power does affect flashover characteristics. The minimum flashover stress by Method b is lower than that by Method a. However, in particular case of Method b with higher snow conductivity, too much discharge activities prevent snow accretion on the insulator. This leads to snow melting or snow shedding.

Artificial pollution flashover performance of porcelain long rod UHVDC insulators at high altitudes

Porcelain long rod insulators are recommended for outdoor insulation of UHV/EHV dc transmission lines because of their excellent service experience obtained in Central Europe. However, very few studies have been conducted on dc pollution flashover performance or the UHVDC insulators at high altitudes. Artificial pollution tests on 300 kN and above porcelain long rod insulators were carried out with dc voltage in natural high altitude areas (about 2000 m), in which the solid layer method was used and the 50% flashover voltage (U50%) was measured with the up-and-down method. Test results show that dc pollution flashover performances of the 300 and 400 kN insulators are similar. The exponents characterizing influence of salt deposit density on the flashover voltage vary from 0.46 to 0.57. A nearly linear relationship between the flashover voltage and the string length of the insulators is presented. Both double suspension strings and tension string patterns have a significant influence on the flashover voltage. The influence of non-uniform pollution distribution between the top and bottom surfaces of the insulator sheds on the flashover voltage is analyzed, and a correction coefficient for the insulators is proposed.

Calculation of Electric Field Characteristics of Insulator Under Sandstorm Condition

Sandstorm has influence on the the electrical properties of outdoor insulator, and the analysis of the electric field characteristics of insulator under sandstorm condition is very important. The electrostatic field finite element method (FEM) is used to calculate the electric field distribution along long rod insulator under sandstorm condition with FEM software after calculating the one under clean condition. The results of calculation show that the sand deposition decreases the electric field strength of insulator covered with sand, and increases the field strength of the corresponding shed key points. The electric field strength of the non-sand region will increase, when the non-sand region appears in sand layer on insulator. Suspended sand particles in the ambient air can distort the electric field distribution along insulator, and which is significantly affected by the size, the quantity, the charge-to-mass ratio and the charge polarity of sand particles. DOI : http://dx.doi.org/10.11591/telkomnika.v12i2.3902

Electric Field Analysis of High Voltage Insulators

This paper involves designing and applying electric field analysis on multiple long rod insulators. Quality HV insulators are an integral part of power systems because they separate the Transmission lines carrying high voltages from the grounded poles. They must have the ability to withstand both high electrical and mechanical stress. So for this purpose modeling of long rod insulator was done with multiple materials such as ceramic, porcelain, and fiber glass and silicon rubber. Electric field analysis can be used to determine voltage profile of each material which in turn can be used to determine how much electrical stress the material can undertake. An attempt was made to model existing long rod insulator designs using software like Solidworks. Subsequently modifications were made to the design by changing parameters such as diameter of the insulator body, angle made by insulator cups etc. These models were then subjected to electric field analysis using finite element analysis software such as Elecnet or Comsol Multiphysics in order to identify the points where maximum electric field stress exists. Further modifications were made on order to reduce and equalize the electric field over the insulator surface.

Comparison of pollution flashover performance of porcelain long rod, disc type, and composite UHVDC insulators at high altitudes

Aiming at porcelain long rod, disc type and composite long rod UHVDC insulators, this paper presents a comparison of their dc pollution flashover performances and an analysis of arcing behavior at high altitudes (1970m). The solid layer method was used in artificial pollution tests, in which sodium chloride and kaolin powder were used to simulate conductive and inert materials. The insulators were wetted by steam fog in a fog chamber. The 50% flashover voltage (U <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">50%</sub> ) was measured with the up-and-down method. According to the test results, the three types of insulators are similar in the characteristic exponent which characterizes influence of the salt deposit density on the flashover voltage. Due to lower utilization ratio of leakage distances, pollution flashover voltage gradient for the porcelain long rod insulators is lower than that for the disc type insulators. Whereas covered with Room Temperature Vulcanized (RTV) silicone rubber coatings on the trunk surfaces, the porcelain long rod insulator is much superior to the disc type insulators in pollution flashover voltage gradient. The dc pollution flashover performance and the utilization ratio of leakage distances for the composite long rod insulators are much better than those for the other two types of insulators, which are induced by the special configuration of composite long rod insulators.

Leakage Currents on Naturally Contaminated Porcelain and Silicone Insulators

The leakage current measurements on standard post insulators and on rod insulators without sheds were carried out. The porcelain and silicone rubber insulators were tested at the Glogow station under the voltage of 75 kV. It was shown that the currents on porcelain insulators are sometimes greater than the currents on silicone insulators. However, the currents on both insulator types are often similar. Silicone rubber insulators are more contaminated than porcelain insulators. The current analysis has been made by using the static theory of pollution flashover.

Increased energy in stable dry-band arcs due to length compression

The occurrence of dry-band arcs on outdoor composite insulators can degrade the polymeric materials¿ surface and ultimately may lead to insulator failure. The degradation processes are generally considered as aging effects occurring over long periods of time, from years to decades. In this paper, it is shown that if a stable dryband arc is physically compressed in length by external forces, such as electrolyte deformation due to wind or gravity, the arcing activities will become more severe. This in turn, may accelerate the degradation into a short time-frame hazard. A series of experiments are carried out to investigate the electrical characteristics of the arcs as they become compressed. In this case experiments are performed on silicone rod insulators at controlled angles to the horizontal. Rapid aging is observed after such events. Measurements of arcing period, peak current, and arc resistance during the arcing compression process are analyzed. Based on the experiments, a `Double Sinusoidal Model¿ is developed to simulate the current-voltage characteristics of dryband arcing during its compression. Both experiment and simulation show that arc power, arc energy and corresponding energy density will dramatically increase if arc compression occurs, which may lead to more rapid and serious damage on composite insulator surfaces than is experienced otherwise. It is suggested that aggressive erosion events may occur in short periods of time within extended test regimes or entire service histories.

Study on AC pollution flashover performance of cap-and-pin and rod insulators at high-altitude sites

The external insulation of electrical equipments is affected by the atmospheric parameters in high-altitude regions. However, there is a lack of studies conducted at the high-altitude sites of 3000 m and above worldwide so far, in contrast to many fruitful ones carried out in the artificial climate chamber. The authors investigate AC pollution flashover performance of cap-and-pin and rod insulators at high-altitude sites with a view to bridging the gap and enriching our understanding in the aspect. The AC artificial pollution tests are conducted at three high-altitude sites of 2820, 3575 and 4484 m, respectively. The results show that the exponents characterising the influence of salt deposit density, non-soluble deposit density and air pressure are 0.297–0.352, 0.122–0.142, 0.535–0.580, respectively; ambient temperature has an obvious effect on the pollution flashover voltages; there is no obvious relation between the insulator profiles and the influence exponents of salt deposit density, non-soluble deposit density, air pressure or ambient temperature.