Outdoor Insulators Research Articles

Novel fabrication of polyethylene glycol/ceramic composite pellets with an excellent phase change shape stable trait and their potential applications for greenhouse insulation

Organic solid–liquid phase change materials (PCMs) face challenges in practical applications due to their susceptibility to leakage during phase transitions. To address this issue, we constructed the polyethylene glycol (PEG)/ceramic pellets (CPs) composite phase change shape stable materials (PCSHs) with thermal energy storage capability, thermal stability, and a firm texture using the melting impregnation method. The PCSHs exhibit remarkable shape stability in the leakage test due to the capillary action and surface tension generated by the micropore structure on their surface. They also can convert light energy into heat and store it as latent heat, achieving an optimal photothermal conversion efficiency of 45.21 % and a maximum melting enthalpy of 13.33 kJ/kg at a PEG loading of ∼ 12 %. An outdoor greenhouse insulation simulation experiment confirmed that the PCSHs can maintain soil temperatures above 30 °C for over 30 min after illumination ceases. This work presents a facile synthesis strategy for shape-stable PCMs with potential applications in greenhouse insulation.

An experimental study of the flashover performances of outdoor high-voltage polymeric insulators under fan-shaped pollution and dry band location

An experimental study of the flashover performances of outdoor high-voltage polymeric insulators under fan-shaped pollution and dry band location

Failure evaluation of outdoor polymeric insulators based on statistical condition-assessment methods

Field aging of outdoor polymeric insulators results in unscheduled outages in power systems particularly in harsh climate conditions. In this paper, a strategic maintenance framework is proposed in order to prevent overhead line outages. The presented scheme is based on condition assessment of the real aged polymeric insulators. Data of tensile test, hardness test, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) are used to extract critical features of the aged samples based on classification of fuzzy c-means clustering. Then, a lifetime prediction analysis is done based on Cox hazards analysis to develop further maintenance strategy. The proposed model is validated through numerical analyses on polymeric insulators for various validation evaluations including pollution severity analysis and hydrophobicity class (HC) measurement. Obtained results verify accuracy of the intelligent model to predict lifetime of the aged polymeric insulators. The presented strategic framework can be effectively applied to online monitoring, condition assessment and preventive maintenance programs of the power system utilities.

Comparison Study of Insulation Performance of Semiconducting Glaze, Ceramic, and Glass Outdoor Insulators with Artificial Conditions

Comparison Study of Insulation Performance of Semiconducting Glaze, Ceramic, and Glass Outdoor Insulators with Artificial Conditions

Mussel-inspired adhesion for layer-by-layer assembly towards multi-functional electrically conductive cotton fabric

Layer-by-layer (LBL) assembly has been widely utilized for constructing functional coatings to fabricate versatile materials. However, challenges arise when the assembly building blocks are electrically neutral. To address this issue, we report the use of mussel-inspired adhesion as a unique driving force for LBL assembly to fabricate electrically conductive cotton fabric (ECCF) with carbon nanotubes & graphene as conductive materials and poly(vinyl alcohol-graft-3,4-dihydroxybenzyl acetal) (PVD) as a mussel-inspired adhesive. The robust adhesion provided by PVD endowed the ECCF with excellent stability against sandpaper friction, tape peeling, and water washing. The use of the ECCF in some advanced application such as strain sensing, temperature sensing, and electric heating was studied in detail. The ECCF exhibited fast response and remarkable sensitivity in strain sensing, enabling real-time detection of various human motions such as bending, twisting, and swallowing. In temperature sensing, the ECCF exhibited a negative temperature coefficient effect and offered a linear response within the temperature range of 30–100 °C. In addition, the ECCF demonstrated exceptional electric heating performance, leading to potential use in outdoor insulation and thermal rehabilitation therapy. This innovative application of mussel-inspired adhesion in LBL assembly not only paves the way for advanced smart fabrics but also enhances functionality.

Aging assessment of silicone rubber materials under corona discharge accompanied by humidity and UV radiation

Abstract High voltage (HV) outdoor insulators are subjected to both electrical and environmental stresses, which may lead to their failure. Among the causes, corona discharge, humidity and UV radiation are considered to be the most damaging factors. Efforts are therefore underway to investigate new materials for improving the performance of insulating systems. In this research work, silicone-based room temperature vulcanized samples filled with alumina trihydrate (ATH), silicon dioxide and magnesium hydroxide (MH) were prepared and exposed to AC corona discharge for a duration of 110 h. The electric discharge was also accompanied by UV radiation and two different humidity levels. Following aging of the test samples, diagnosis was conducted to assess their integrity. Measurements based on determining the static contact angle demonstrated the loss of hydrophobicity of all the materials, while hydrophobicity recovery phenomena revealed that ATH-doped materials demonstrated a comparatively higher increase in the contact angle than in samples filled with silicone dioxide (silica) and MH. Scanning electron microscopy analysis revealed deep cracks and block-like structures on their surfaces. Similarly, energy-dispersive X-ray analysis indicated the signs of surface oxidation of the aged samples. However, the data of elemental composition exhibited the loss of filler contents as well as that of carbon from the base matrix. The overall assessment showed that resistance to suppress aging is influenced by both the filler type and its concentration in the investigated composites. The ATH-filled composites exhibited outstanding performance when exposed to the rigors of corona discharge and other environmental stresses. This research contributes to materials science and HV engineering by addressing the development of composites for enhanced insulator performance, with future aspects lying in the utilization of nano-composites for advanced functionality and durability.

Preparation and mechanism research on hydrophobic coupling modification of HTV silicone rubber

Neat high-temperature vulcanized silicone rubber (HTV SR) showed bad hydrophobicity due to the existence of a large number of inorganic reinforcing fillers on its surface, which affected its security application in outdoor insulation systems. In this work, hydrophobic silane chains were grafted onto the surface of inorganic particles on the skin layer of HTV SR by a one-step coupling modification to improve its hydrophobicity. The effects of coupling agent types and coupling reaction conditions on the hydrophobicity of HTV SR were investigated. It was determined that the perfluorooctane trichlorosilicon with a large number of low surface energy fluorine atoms was the preferred coupling agent. The contact angle of HTV SR was increased by 15.70% when the optimal coupling reaction conditions were determined to be a reaction temperature of 60°C, a reaction time of 4 h, and an amount of coupling agent of 0.5%. The study found that both etching reaction and grafting reaction occurred during the whole coupling modification process, which led to the disappearance or decrease of a lot of holes on the HTV SR surface. After the fluorination coupling reaction, the surface of HTV SR became smooth and dense that led to the decrease of water absorption. The result of Fourier-transform infrared spectroscopy analysis showed the formation of C-F bond in HTV SR after fluorination modification, and the energetic dispersive spectroscopy analysis showed that the fluorine content on the surface of the fluorinated HTV SR increased significantly. Moreover, the stability analysis showed that the fluorinated HTV SR still had a good thermal stability and mechanical property stability.

A novel application of artificial intelligence technology for outdoor high-voltage composite insulator

The distribution of the electric field plays a crucial role in evaluating the effectiveness of composite insulators. This research presents an innovative approach for optimizing the design of corona rings, aiming to decrease the electric field intensity in critical areas to satisfactory levels. The investigation examined the correlation among corona ring design variables and the intensity of the electric field close to the energized-end fitting in a 220 kV composite insulator equipped with a corona ring. Using design of experiment methods, the impact of three corona ring design parameters – corona ring diameter (R), ring tube diameter (Dr), and corona ring height (H) – was assessed. A novel nonlinear mathematical objective function was formulated, connecting the electric field magnitude to the structural parameters of the corona ring. Subsequently, the Bat algorithm, a bio-inspired optimization technique, was employed to enhance the initial corona ring design and mitigate the electric field intensity. Finally, the Finite Element Method (FEM) was utilized to simulate and evaluate the voltage distribution and electric field stress. The optimization process resulted in a substantial decrease in the highest electric field magnitude, by 58.6 % compared to the insulator with the threshold value, and 75 % when devoid of a corona ring. Additionally, the research highlighted the significant influence of ring tube thickness on the distribution of the electric field. The combination of experimental design and the Bat algorithm proved to be a powerful tool for optimizing the design of corona rings on transmission line composite insulators, providing precise solutions for optimizing corona discharge problems and enhancing the reliability of power transmission systems.

Regulation of near-infrared absorbing property for the absorptive short-wave pass filter based on Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx quasi-optical microcavity

Regulation of the near-infrared absorbing property in the different spectral ranges has been a challenge for absorptive short-wave pass filters (ASPFs) to meet the increasing application demands. In this paper, the multi-layer ASPF with the film structure of substrate(quartz)/Si3N4/ Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx/SiO2 is designed and prepared by magnetron sputtering. We get an optimal spectral selectivity in that the transmissive band ranges from 380-700 nm with a peak transmittance of 72.9 %, and the absorptive band ranges from 700-1400 nm with a peak absorptance of 84.1 %. As the main part of the ASPF, the quasi-optical microcavity (QOM) is creatively constructed with the film structure of Ag:1st/Si3N4/SiO2/Si3N4/Ag:2nd/Si3N4/W-WOx, integrating the interference mechanism and surface plasmon resonance mechanism with the intrinsic spectral selectivity of the W-WOx and silver layers, achieving the good selective absorbing property. The absorptive band is widened from 700-1400 nm to 700–2500 nm by regulating the interference effect and the intrinsic property via changing the thickness of the W-WOx layer, realizing much more significant regulation. The optical property remains stable after heat treatment at 200 °C for 72 h in the air, showing better thermal stability than other ASPFs. The outdoor thermal insulation experiments show that the temperature of black paint under the ASPF is about 17 °C lower than that under quartz glass. The microscopic and optical mechanisms for regulating the optical properties have been analyzed in-depth, providing a new strategy for the development of ASPFs.

INFLUENCES OF NANOPARTICLES ON DIELECTRIC FLUID TRANSFORMERS: A REVIEW

Applications of nanoscience & nanotechnology have produced advanced materials & demonstrated impressive development in a number of industrial domains. Many technological advancements & research & development initiatives involving nanotechnology concepts are underway these days in an effort to ace the performance & dependability of traditional materials. The electrical sector has been benefited from these nanotechnology initiatives by seeking applications for its various apparatuses, such as electrical transformers, which are regarded as one of essential parts of the electrical grid. This paper presents an extensive assessment of the literature on the uses of nanotechnology principles for transformers, with a focus on studies pertaining to dielectric fluids, monitoring systems, solid or outdoor insulators & many other components. The most recent research on the use of nanomaterials in transformer applications has been examined and documented. Furthermore, prospects for further investigation

Electrical Properties of Silver-Silicone Rubber Nanocomposites for High-Voltage Outdoor Insulators

Electrical Properties of Silver-Silicone Rubber Nanocomposites for High-Voltage Outdoor Insulators

Leakage Current Harmonic Index as A Diagnostic Technique for Tool to Assess the Surface Condition Assessment of Aged Insulator Surface Under Varying Humidity

Leakage current has been widely utilized as an effective means to monitor the pollution severity of outdoor insulators. The indices of the odd harmonic components of the leakage current have proven to be reliable indicators of insulator performance, particularly in the third to fifth harmonic orders. However, significant challenges exist in using these indices to monitor and classify the leakage current of aged insulators under varying harmonic and pollution conditions. This paper introduces the harmonic index K((3/(5+7) ) which employs third up to seventh odd harmonic component of the leakage current as a diagnostic tool to determine the pollution severity of aged insulators under light, medium and heavy contamination levels. The experiments were conducted using 12 different sets of 11kV insulators with varying degrees of aging. The results indicate that the harmonic index Ki for new and moderately aged insulators decreases with an increase in contamination and is lower than that of heavily aged insulators.

Pultrusion made materials for outdoor insulation and their HV tests

Pultrusion made materials for outdoor insulation and their HV tests

Online Measurement of Voltage Gradient Distortion and Leakage Current of Heavily Contaminated Outdoor Insulation Using Thermal Imaging

Online Measurement of Voltage Gradient Distortion and Leakage Current of Heavily Contaminated Outdoor Insulation Using Thermal Imaging

Performance Evaluation of Developed Superhydrophobic Coating for Polymeric Outdoor Insulators

Performance Evaluation of Developed Superhydrophobic Coating for Polymeric Outdoor Insulators

Superhydrophobic coating for enhancing porcelain insulators performance under pollution conditions

The outdoor insulators suffer external effects that adversely impact their performance and lifespan. Wettability and pollution have a negative role by increasing the likelihood of insulators surface flashover. Coatings are applied on the insulators to enhance surface hydrophobicity to cope with these external effects. Besides experimental testing, simulating the electric field distribution is a useful tool to study the insulator performance and where the surface discharges initiate. In this work, finite element method simulation is used for analyzing the electric field distribution of uncoated and coated insulators under different environmental conditions. The case of uniformly distributed wettability/pollution and perfect coating, with same thickness, on insulators surfaces is assumed. Cap and pin U40B-class porcelain 11 kV single disc and 33 kV three discs string insulators are considered. The studied coatings include two conventional hydrophobic, Al2O3 and RTV-SR, and one proposed superhydrophobic PTFE materials. The results of the maximum electric field of coated insulators are compared with respect to their equivalents of wet-polluted uncoated insulators. The proposed PTFE coating yielded the highest percentages of maximum electric field reduction compared to the other two conventional coatings. The PTFE coating for 11 kV single porcelain insulator yielded reduction for the maximum electric field by 84.754 % under rain condition and 98.848 % under fog condition while for 33 kV three discs string porcelain insulators, the percentages reached 84.288 % under rain condition and 97.315 % under fog condition. PTFE material has a good potential for insulator coating yielding less flashover likelihood and better insulator performance under pollution conditions.

Enhancing flame and electrical surface discharge resistance in silicone rubber composite insulation through aluminium hydroxide, clay, and glass fibre additives

Silicone rubber (SR) is a leading polymer used in electrical outdoor insulation applications due to its superior hydrophobic characteristics. However, the low flame and electrical surface discharge resistance of SR limit its broad viability and challenge its integrity in severe outdoor working conditions. This work attempts to explore the flame retardancy and surface discharge characteristics of SR co-filled with aluminium hydroxide (ATH), nanoclay montmorillonite (MMT), and chopped glass fibre (GF). Results indicate that the incorporation of ATH/MMT/GF could assist in improving the fire and surface discharge resistance of the SR material. It is noted that the maximum average rate of heat emission (MARHE) and total smoke production (TSP) are measured at 24.93 kW/m2 and 0.48 m2 in SRE, relative to 61.29 kW/m2 and 6.02 m2 in SRB. Using finite element analysis (FEA), the maximum electric field strength is computed at 4.66 × 106 V/m in the air gap coupled with a high-voltage (HV) plate and sample. SRE exhibits a higher partial discharge inception voltage (PDIV) value of 2.32 kVrms than its counterparts, while the maximum discharge magnitude (Qmax) is computed at 7095 pC, relative to 7746 pC in SRB. SRE emerges as a preferable SR composite to be used in electrical insulation applications with excellent flame and surface discharge resistance characteristics.

Risk assessment of contaminated composite insulators in pre-flashover conditions

In this paper, a novel approach for risk assessment of the outdoor polluted insulators is presented to predict dry band-arcing and flashover. Risk evaluation of the dry-band arcing and flashover are represented using leakage current (LC) behavior in order to understand pollution behavior of the pre-flashover conditions. Critical indexes of the dry-band arcing and flashover are extracted based on the presented risk assessment model using wavelet transform (WT). Then, the developed critical indexes are used for prediction of the operation risk of the composite insulators. In addition, the occurrence probabilities of the dry band arcing and flashover are calculated based on the analysis of critical indexes. Several sensitivity parameters including pollution level, wetting rate and geometry specification are considered in the presented model. Validation results show that risk of the insulator's service can be correlated to the represented critical indexes. The proposed approach can be adopted as an online monitoring tool in order to avoid pollution flashover of the outdoor insulators.

Failure analysis of polymeric outdoor insulators used in HVDC converter stations

This study presents the performance of polymeric outdoor insulators used in high-voltage direct current (HVDC) converter stations. These insulators typically encounter voltage polarity reversal based on the power flow direction, which may occur within days or months. The accelerated aging investigations are conducted on composite insulators adopting the rotating wheel experimental facility and considering the voltage polarity reversal effect. A two-dimensional model for the evaluated insulators is developed and simulated in COMSOL Multiphysics to comprehensively understand their performance under various environmental conditions. It is observed that the voltage polarity reversal significantly impacts the degradation and aging of composite insulators—the leakage current increases after each polarity reversal with higher surface temperatures. Additionally, unique patterns were observed on both sides of the housing sheds. However, these patterns were only observed on one side in the case of a single polarity. The failure of insulators was noticed after 625 h with multiple consecutive flashovers, indicating the severe deterioration of the silicone rubber housing. In addition, physicochemical analyses were conducted on the aged samples collected from various locations to identify their degradation level. Results obtained indicate a significant deterioration of silicone rubber housing, especially near the shank areas. Moreover, aged samples showed a substantial deterioration of the mechanical and hydrophobicity properties.

Environmental Effects on Parameters of Leakage Current Equivalent Circuits of Outdoor Insulators

The performance of outdoor insulators in transmission lines may deteriorate due to aging and can even be enhanced by the presence of pollutants. Leakage current (LC) measurement is one of the most effective methods to diagnose the insulator condition, utilizing LC parameters such as magnitude and total harmonic distortion (THD). However, research on the interpretation of these parameters is still limited. This paper discusses the diagnostic method by simulation, employing the LC equivalent circuits of different types of insulators and examining the influence of environmental factors, such as humidity and pollutant levels. LC waveforms are first obtained through experiments on various insulator types, including traditional ceramic and glass insulators, advanced composite insulators, or the hybrid type of RTV silicone rubber-coated and conducting glazed insulators. Subsequently, simulations on the LC circuits of Suwarno’s and Kizilcay’s models are performed to obtain similar LC waveforms and properties. The values of the equivalent circuit parameters are then used to diagnose each insulator’s characteristics and environmental effects. The results indicate that composite insulators of epoxy resin or SiR have a larger intrinsic resistance of ~40 GΩ and nonlinear resistance (a few MΩ to tens of GΩ), representing high surface resistance of the insulators against water and pollutants. A comparison of these parameters is expected to indicate the severity levels of insulator condition. Doi: 10.28991/ESJ-2024-08-01-022 Full Text: PDF