High Temperature Vulcanized Research Articles

Effect of Titanium Dioxide on Cure Characteristics and Physico Mechanical Properties of High-Temperature Vulcanizing Silicone Rubber Composites

Silicone rubber (SiR), a vital elastomer, is extensively used in producing various engineering and general products, owing to its distinctive properties. Despite the remarkable properties, SiR-based products require anti-microbial agents such as titanium dioxide, TiO2 to negate black mold issues. Still, adding this agent alters the composites' processability and physical and mechanical properties. This study examined the impact of adding different TiO2 content as fillers on silicone rubber composites' processability, physical properties, and mechanical properties. Raw materials of 20-hardness high-temperature-vulcanization (HTV) SiR- reinforced with various TiO2 contents at 0.0, 0.3, 0.6 and 1.2 wt% were prepared using a two-roll mill. The results indicated SiR composites reinforced with 0.3 wt% TiO2 exhibited the best performance with a tensile strength of 1.49 MPa, elongation at break of 340.87%, modulus 100% of 0.664 MPa, modulus 300% of 0.822 MPa, and modulus 500% of 0.954 MPa. This performance can be attributed to the efficient crosslink density and the effective interactions between the TiO2 and silicone rubber particles at this concentration. Structural and morphological analyses further corroborated the results. Consequently, it can be inferred that silicone rubber reinforced with 0.3 wt% titanium dioxide holds the potential for formulating silicone rubber compounds that necessitate anti-microbial properties.

Production and an advanced model for electrical conductivity of silicone rubber/carbon nanotube nanocomposites as outdoor insulator housing material

Considerable cause of the condensation mechanism of moisture and fog on the contaminated high-voltage insulator surface is the temperature difference between the insulator surface and the dew point which eventuate owing to the mechanism of radiative cooling. Condensation of moisture leads to creating a conducting path on the insulator surface and make the insulator to be a conductor and results in the electrical transmission line failure. In order to cover the above-mentioned temperature difference, carbon nanotubes (CNTs) are being applied to the silicone rubber which is the insulator housing material. This study is based on joule heating generation which decrease the electrical resistance of the high-voltage insulator surface. An advanced mathematical model which is based on Pukanszky formulation for estimation of composite tensile strength was presented for the effectual electrical conduction of silicone rubber - carbon nanotube nanocomposite (SCNT). SCNT samples were produced by the addition of dissimilar CNT concentrations to a high temperature vulcanizing (HTV) silicone rubber by solution-blending method. Comparison between experimental results and theoretical forecasts showed an excellent agreement. The obtained model disclosed that the lower ranks of tunneling resistivity and distance, the higher magnitudes of tunneling diameter, the higher concentration of longer and thinner CNTs, lower CNT curliness, higher fraction of networked CNTs, and deeper interphase can produce the maximum level of SCNT conductivity.

Visual characterization of pollution and moisture parameters of the polluted HTV silicone rubber surface with hyperspectral imaging technology

The application of high temperature vulcanized (HTV) silicone rubber materials in transmission lines insulators has been extensive. However, with the accumulation of pollution and moisture on the surface of HTV silicone rubber, the insulation reliability gradually decreases, which may even lead to flashover. In this paper, hyperspectral imaging technology is utilized as a rapid and effective tool for the visual characterization of pollution and moisture parameters of the polluted HTV silicone rubber. Based on the analysis of reflection spectra, it has been determined that the pollution degree has a positive effect and the moisture content has a negative effect on the reflection characteristics of HTV silicone rubber, respectively. Further quantitative analysis of reflectance values at various moisture conditions reveals that exponential relationships can be observed between reflectance values and moisture contents at a certain wavelength. At the same time, linear correlations between reflectance values and pollution degrees (quantified as equivalent salt deposit density (ESDD)) at a certain wavelength are also proposed. By integrating the exponential and linear relationships, a double-exponential model is formulated to concurrently characterize the ESDD and moisture content (MC). Furtherly, from the perspective of engineering application, to enhance the model’s robustness, a set of equations combining spectral indexes and spectral shape feature parameters is initially formulated for the calculating of ESDD and MC. Given the synchronous inversion and visualization capabilities of pollution and moisture parameters of the polluted HTV silicone rubber surface, the visual characterization model serves as a valuable tool for protecting against pollution flashover failures and designing power equipment insulation.

ANALYSIS OF LEAKAGE CURRENT ON POLYMERIC INSULATOR UNDER RAINFOREST ENVIRONMENT

This paper develops a Finite Element Model (FEM) for a 138 kV High Temperature Vulcanized (HTV) Silicone Rubber (SiR) transmission insulator in which, in a first step, leakage current is calculated for different non-uniform continuous and discontinuous pollution deposits and then features based on the phase shift between the leakage current and the applied voltage are extracted for each kind of pollution layer to identify the existence of dry bands on the insulator surface. A phase shift of 84.75° lag between the leakage current and applied voltage was found for a pollution layer with dry bands inserted. This results evidence that the phase angle can be used to detect the dry band formation by measuring the leakage current and its phase angle.

Electrical Conductivity Modeling and Fabrication of Carbon Nanotubes/Silicone Rubber Composites for High Voltage Insulators in Regions With a Polluted Atmosphere

The condensation mechanism of the insulators’ surface, increase the surface electrical conductivity. The electrical conductivity of the insulator creates a high level of leakage current and causes the failure. Difference between the dew point and the surface temperature of the insulator which occur due to radiative cooling mechanism, is the major reason of the moisture condensation on the polluted insulator surface. To compensate for the temperature difference, carbon nanotubes (CNTs) are being added to the silicone rubber housing material. The main idea of this research is based on generating joule heating by reducing the surface resistance of high voltage insulators. For this purpose, a developed model based on Halpin–Tsai formulation for tensile modulus of nanocomposites is joined with the conventional power-law model for the effective electrical conductivity of silicone rubber matrix carbon nanotube composite (SMCNT). SMCNT samples are prepared with the addition of various CNT volume fractions to high temperature vulcanizing (HTV) silicone rubber by melt-blending method. The developed model reveals that the high fraction of thinner and longer CNT, thicker interphase, higher concentration of percolated CNT, lower waviness of CNT, and higher conductivity of CNT can make a higher effective conductivity for SMCNT.

Mechanical Properties of High Temperature Vulcanized Silicone Rubber Aged in the Natural Environment.

Composite insulators operate in harsh field environments all year round. Their various properties and states of aging require attention. It is important to study the performance changes of composite insulator sheds after aging to evaluate the life of insulators operating on grids. For this reason, 22 composite insulator sheds from different factories, with different voltage levels and different ages years were selected to conduct mechanical properties testing. The mechanical properties include hardness, tensile strength, and elongation at break, and were investigated by thermogravimetric (TGA) testing, surface morphology, and nuclear magnetic resonance (NMR) characterization. The changes in mechanical properties of high temperature vulcanization (HTV) composite insulator silicone rubber aged in the natural environment were analyzed, including the reasons for these changes. The results showed that the transverse relaxation time T2 of the sample was closely related to its aging state. The more serious the silicone rubber’s aging, the smaller was the T2. The state of the composite insulator can be evaluated by using T2 and aging years simultaneously. With the actual degree of aging in the silicone rubber intensified, its tensile strength and elongation at break generally showed a downward trend.

Energy Balance Model for Providing Mechanistic Insights Into HTV and LSR Performance in Inclined Plane Tests

Silicone rubber (SR) is widely used in external insulation. However, the utilization of either high-temperature vulcanized (HTV) SR or liquid SR (LSR) remains controversial in China because of their differences in tracking and erosion resistance and aging resistance due to various amounts of nonreinforcing fillers. Here, the tracking and erosion behaviors of HTV and LSR during the inclined plane test (IPT) are captured and compared for a detailed comprehension of the difference between the two materials. The results revealed that LSR was easily carbonized and formed electrical tracks initially. Then, the carbonization slowed because of developing a protective ceramic layer. The relatively stable ceramic layer resulted in less frequent rapid erosion but increased the average arc burning time. An energy balance model of dry-band arcing (DBA) was established to evaluate DBA’s energy dissipation and absorption. Then, the emission spectra of DBA were collected to analyze the arc temperature and resistance more accurately. The energy input from the system is dissipated primarily through heating and evaporation of the liquid film, with radiant energy only accounting for a minuscule fraction. In different erosion states, the power absorbed by the surface of samples is different. LSR shows an average absorption power of 19.9 W in the initial carbonization state, which is higher than that of HTV (16.5 W). The average absorption power in the fast erosion state is the same for both samples at about 30 W. The absorption power at 20–25 W is considered the threshold range of relatively stable erosion.

Effect of extraoral aging conditions on the color stability of high temperature vulcanizing and room temperature vulcanizing maxillofacial silicone elastomers: An in vitro study

Maxillofacial prostheses require enhancement or replacement due to deterioration in their color during their use. The major factors that affect the color of the prostheses are ultraviolet (UV) light exposure, temperature changes, and cleaning and handling by the patient. The aim of the study was to find the effect of extraoral aging conditions on the color stability of high temperature vulcanizing (HTV) and room temperature vulcanizing (RTV) maxillofacial silicone elastomers. Specimens of 25mm x3mm dimensions were fabricated in Techsil S25 HTV silicone and Factor II RTV silicones and processed according to the manufacturer’s instructions. Eight groups with eleven specimens each were made. The color stability test was conducted with a Ultraviolet- visible (UV-VIS) spectrometer (Shimadzu) before and after exposure to outdoor weathering and disinfection. The results of the two groups were compared using independent t test. The results of the subgroups were compared with One way ANOVA test followed by Scheffe multiple comparison test. The average color change was found highest in subgroup 4(3.90) and least in subgroup 3(2.3) in HTV samples. The average color change was found highest in subgroup 1(2.70) and least in subgroup 2(1.78) in RTV samples. Color changes caused by HTV samples were significantly greater than that caused by RTV samples. Color changes caused in subgroups 2 and 4 between HTV and RTV samples were significantly greater than in the other groups. There were no significant differences in color change in other subgroups.

Investigation of high temperature vulcanized and room temperature vulcanized silicone rubber based on flexible piezo‐electric energy harvesting applications with multi‐walled carbon nanotube reinforced composites

AbstractFlexible energy harvester can be able to produce continuous voltage output under the mechanical deformations. High temperature vulcanized (HTV) and room temperature vulcanized (RTV) silicone rubbers are used for making the flexible piezo‐electric energy harvester. A total of 1 and 2 phr of multi‐walled carbon nanotube (MWCNT) are used as the electrode material mixed with the rubber solution for the preparation of flexible electrode. Cyclic loading machine is used for the application of 2 Hz of bi‐axial load and uniaxial compression load in the specimen. One centimeter depth of displacement is applied during the bi‐axial cyclic loading and 4 mm amplitude of displacement is applied during the compression loading. Tensile and compression tests are performed to determine the engineering properties of the material. Tensile load withstanding value of the silicone rubber is increasing as increasing the MWCNT filler in the rubber. Tensile value of the pure HTV silicone rubber is 10.020 N and for 2 phr MWCNT reinforced rubber is 22.106 N. Compressive withstanding load of pure HTV rubber is 189.565 N and for 2 phr MWCNT reinforced rubber is 287.066 N. HTV silicone rubber is the highly stiffness material on compares with RTV rubber based on the tensile and the compressive value. Transmission electron microscopy, optical micrographs, and scanning electron microscope show the morphology of MWCNT and surface image of specimen. A total of 2 mm substrate based 2 phr MWCNT reinforced HTV flexible energy harvester undergo decrease in voltage during the cyclic loading due to breakage of electrode. A total of 2 phr MWCNT electrode‐based sample can be able to produce more output voltage than 1 phr MWCNT electrode‐based sample during bi‐axial and compression loading. More voltage is produced in the compression specimen than bi‐axial one.

Effect of Acidic-fog on performances of HTV silicone rubber with AC energized

The performance of high temperature vulcanized (HTV) silicone rubber used in composite insulator will be worse in harsh environment. The acid-base pollutants in the environment have a great influence on the performance of silicone rubber. As one of the aging factors of composite insulators, acid corrosion has not been studied deeply. In this paper, the AC charged aging test of the silicone rubber sample in an acid environment was carried out, and then its physicochemical and electrical properties were tested, including microscopic morphology, hydrophobicity, infrared spectroscopy, and electrical strength. The effect trends of duration time, charged voltage and acid pH value on material properties are studied. The results show that under the combined action of acid-fog and voltage, the performance of silicone rubber will be degraded. The smooth structure of the surface of the material is destroyed, the side chains of the polymer are severely cut, and the hydrophobicity becomes worse. The AC flashover voltage along the surface has a power function relationship with the pH value. Continuous deterioration of composite insulators may occur in acid polluted areas for a long time.

A Proposal for the Evaluation of HTV Silicone Rubber Composite Insulators.

This paper describes in detail a step-by-step methodology for obtaining specimens from the housing material (high temperature vulcanized (HTV) silicone rubber with aluminum trihydrate (ATH) filler) of composite insulators (finished products), for five well known and commonly used tests. The aim of the paper is to render practical clarifications and additions to the instructions for five tests on composite insulators provided by international standards. Additionally, the ranges of the results of these tests are presented. More specifically, shore A hardness measurement, tensile strength and elongation at break test, tear strength test, density measurement and inclined plane test were conducted on the housing material of ten, new, unaged medium voltage composite insulators made by six different manufacturers. The results of these tests are presented as a contribution to the existing knowledge and a comparative study of corresponding results of previous investigations is performed. The presented procedures for specimens’ preparation, as well as the results (arithmetical ranges), could be used as guidelines for future testing on the housing material (HTV silicone rubber with ATH filler) of composite insulators, either by researchers and manufacturers, during laboratory testing and material development processes, or by customers (distribution and transmission networks owners), during batch acceptance tests.

Evaluation of Erosion Discharge Characteristics in Inclined Plane Tracking and Erosion Tests on Silicone Rubber under AC and DC Voltages

This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps.

Cracking mechanism and degradation performances of HTV silicone rubber with interfacial defects under acid and thermal stress

High temperature vulcanized (HTV) silicone rubber (SIR), as the sheath of composite insulators, is widely used as the insulation device in transmission lines due to their excellent hydrophobicity and pollution flashover resistance. However, the interfacial defects of insulators and severe operating environment will accelerate the aging of HTV SIR sheath, seriously affecting the operation reliability of electrical equipment. Herein, the samples designed with different sizes of interfacial defects are aged under water, sulfuric acid and nitric acid at 80 °C, respectively. The results show that a large number of cracks appear on the surface of HTV SIR samples with interfacial defects after nitric acid treatment at 80 °C for more than 2 days, while samples with no interfacial defects aged under same condition for 8 days maintain unchanged. According to the results of the micro morphology of the sample, the crack is caused by the interfacial stress of the sample. In addition, after nitric acid treatment, the thermal stability, tensile and dielectric properties of HTV SIR with interfacial defects decreased significantly. The initial decomposition temperature decreases by about 30 °C, while the residual weight increases by about 2.5%. Meanwhile, the tensile strength and fracture strain decrease from 4.58 MPa and 470% to 2.07 MPa and 130% respectively, proving that cracks caused by interfacial defects can critically avianize the mechanical properties and thermal stability of HTV SIR. Also, there is an extra dielectric loss peak appearing in the frequency range of 102–104 Hz, which attributed to water invading and the MWS polarization at cracks. By aging HTV SIR with artificial interfacial defects under thermal and acid stress, the HTV SIR cracking phenomenon of composite insulators under severe operating environment is successfully simulated. This work can provide theoretical support ulteriorly for studying the cracking mechanism and the corresponding aging characteristics of HTV SIR used in composite insulators.

Comparative Properties of HTV Silicone Rubber for Composite Insulators—ATH and Silica Fillers

This paper presents a comparative evaluation of high temperature vulcanizing (HTV) silicone rubber consisting of ATH and silica fillers for use as the housing of outdoor composite insulators. Various volume filler fractions (vol%) of alumina trihydrate (ATH) and silica (SiO2) and several median particle sizes are incorporated into HTV silicone rubber and evaluated for erosion and tracking resistances using the inclined-plane tracking and erosion tests (IPT), in accordance with IEC 60587 at several AC test voltages. Test durations, eroded masses, erosion depths, and leakage currents are reported. The dry-band arcing temperatures of the various samples are recorded during the tests. The results show that at 30 vol% filler fractions, ATH filled samples show lower erosion than the corresponding silica filled samples; however, at 15 vol% fraction, the silica filled samples show lower erosion. For most tested conditions, the maximum dry-band temperatures of the silica filled samples are lower than the corresponding ATH filled samples.

A metal-ceramic-rubber composite for hybrid gamma and neutron radiation shielding

In this study, silicone rubber (polydimethylsiloxane) matrix was incorporated with bismuth (III) oxide and hexagonal boron nitride (hBN) functional fillers to develop a flexible composite material that can shield both neutron and X/gamma radiations. Bismuth, as having a high atomic element weight is a very effective material for X/gamma electromagnetic radiation shielding, while hBN has a very high neutron cross-section due to its boron and nitrogen contents. On the other hand, the matrix material that is high temperature vulcanized (HTV) silicone rubber has superior properties of good flexibility, high transparency, and mechanical properties. Hexagonal boron nitride has unique properties and has a similar structure with graphite that is used for neutron moderation. Mechanical test results showed that the elastic modulus of the optimum sample has improved 4 times compared to control sample. Thermal, X ray and neutron attenuation tests were carried out for the developed composite materials. The curing behaviour was investigated in detail using Moving Die Rheometer. Kinetic studies of the vulcanization process were carried out in a very detailed way and high regression values up to 0.98 has been achieved. Non-destructive radiography images were taken to investigate the particle distribution and radiation attenuation of the prepared composites. It was seen that the composite material developed has a considerable attenuation ratio for both neutron and X/gamma radiations. X-ray attenuation test results for silicone rubber containing 20% Bi2O3 and 20% hBN with thickness of 6.4 mm were shown that the intensity of the incoming rays attenuated by 84.1%. Metal-ceramic-rubber composite material with 6.6 mm thickness shielded 65.8% of incoming neutrons.

Wettability behavior and anti-icing property of superhydrophobic coating on HTV silicone rubber

Composite insulators, which use high temperature vulcanized (HTV) silicone rubber as shed material, are widely applied in transmission lines. Ice accumulation on their surfaces may inflict flashover accident and even massive power outage. In this study, a superhydrophobic (SH) coating on HTV silicone rubber was fabricated by the sol–gel process combined with the plasma jet treatment method. It was found that the as-prepared SH coating exhibited prominent superhydrophobicity and an excellent self-cleaning property with a water contact angle of 160.15°, a contact angle hysteresis of 0.60°, a sliding angle of 1.8°, and a surface free energy of 0.1421 mN/m. The anti-icing behavior of water droplets on the as-prepared SH coating surface was investigated at a low temperature of −30 °C and compared with that of the HTV silicone rubber surface. The results indicated that the freezing time on the SH coating was postponed obviously and was as long as 150 s. The SH coating surface exhibited about 5.6 times delay in freezing at −30 °C compared with the HTV silicone rubber surface. Furthermore, heterogeneous nucleation theory and heat transfer theory were introduced to explain the difference in freezing time between the as-prepared SH coating and HTV silicone rubber. It could be concluded that the SH coating had a large nucleation free energy barrier and a low heat transfer rate between the droplet and the surface and, thus, was able to effectively delay the freezing time.

Utilization of positron annihilation and electrochemical impedance to study the microstructure variations and water diffusion of NO2-oxidative-damaged silicone rubber

Silicone rubber is widely used in power grids, electronics and aerospace, because of its hydrophobicity, high flexibility, etc. However, it is susceptible to some environmental chemical factors, such as NO2 and ozone, which can induce chain scission, the generation of defects and the ingress of water. In this work, we systematically studied the microstructure variations and water diffusion behavior of high-temperature vulcanized (HTV) silicone rubber after NO2-induced oxidative damage. Microstructure evolution in silicone rubber was investigated by positron annihilation lifetime spectroscopy (PALS). The results show that the oxidation of NO2 significantly degrades organic matrices, which induces the decrease of crosslinking degree and the formation of defects compared to virgin samples. The water transportation was evaluated by electrochemical impedance spectroscopy (EIS), which showed that the diffusion coefficient, under the NO2 concentration of 28.75 mg L−1, is 106 times that of virgin sample with a water uptake of 31%. Particularly, when the concentration reaches the critical value around 17.25 mg L−1, the diffusion coefficient and water uptake increase sharply, and the calculated average porosity of samples also dramatically increases by 4 orders of magnitude. These indicate the formation of more nano- and micron holes, serving as a pointer for percolation of defects in silicone rubber bulk. The study of microstructure variations and water transportation can help us to understand the aging mechanism, design reasonable composite polymer materials and prevent the damage of chemical contact.

English

As there is an increase in the rate of oral cancer,the surge for the various maxillofacial materials is increasing as well. Materials used for rehabilitation of congenital or acquired defects of patients should fulfil the requirements such as function, longevity, and aesthetics. Defects of face which may be congenital or acquired makes the condition of the affected person very disastrous mentally, physically as well as emotionally. Patient wants facial rehabilitation for a healthy happy life. To provide rehabilitation of these patients, re-evaluation of materials used in the field of maxillofacial prosthesis seems essential. Maxillofacial material should best suit the ideal selection criteria to satisfy the functionality, biocompatibility, aesthetics as well as durability. While the new materials have exhibited many desirable properties, there are also many insufficiencies involved in it. This article presents a systemic review of the evolution, current trends, and future requirements in maxillofacial materials for ensuring psychological well-being. In the recent years, a dramatic increase in the demand for prosthetic rehabilitation of patients with facial defects is seen. Increasing awareness of cancer is resulting in earlier diagnosis and treatment. Unfortunately, many of the surgical techniques are extensive and thus leave large defects that compromise not only function and aesthetics, but also psychosocial status of the patient. These problems require prompt rehabilitation with surgery or prosthetics.1 However, surgical reconstruction is often contraindicated in the presence of large defects or in high-risk patients. Prosthesis offers the advantage of quick, reversible and medically uncomplicated rehabilitation. In addition, the restoration may be readily removed to allow evaluation of the health of the underlying tissues. Historically, many types of materials have been used. Wood, wax metals, vulcanite and many types of plastics have been used as rigid materials while flexible ones like gelatin glycerine mixtures, latex and elastic plastics have also found some usefulness.2 Presently, materials used for the maxillofacial prosthesis are vinyl plastics, polyurethane, silicone rubber and acrylic types. KEY WORDS Maxillofacial-Materials, HTV (High Temperature Vulcanized) Silicone, RTV Silicone

Prediction of Critical Flashover Voltage of High Voltage Insulators Leveraging Bootstrap Neural Network

Understanding the flashover performance of the outdoor high voltage insulator has been in the interest of many researchers recently. Various studies have been performed to investigate the critical flashover voltage of outdoor high voltage insulators analytically and in the laboratory. However, laboratory experiments are expensive and time-consuming. On the other hand, mathematical models are based on certain assumptions which compromise on the accuracy of results. This paper presents an intelligent system based on Artificial Neural Networks (ANN) to predict the critical flashover voltage of High-Temperature Vulcanized (HTV) silicone rubber in polluted and humid conditions. Various types of learning algorithms are used, such as Gradient Descent (GD), Levenberg-Marquardt (LM), Conjugate Gradient (CG), Quasi-Newton (QN), Resilient Backpropagation (RBP), and Bayesian Regularization Backpropagation (BRBP) to train the ANN. The number of neurons in the hidden layers along with the learning rate was varied to understand the effect of these parameters on the performance of ANN. The proposed ANN was trained using experimental data obtained from extensive experimentation in the laboratory under controlled environmental conditions. The proposed model demonstrates promising results and can be used to monitor outdoor high voltage insulators. It was observed from obtained results that changing of the number of neurons, learning rates, and learning algorithms of ANN significantly change the performance of the proposed algorithm.

Forecasting Flashover Parameters of Polymeric Insulators under Contaminated Conditions Using the Machine Learning Technique

There is a vital need to understand the flashover process of polymeric insulators for safe and reliable power system operation. This paper provides a rigorous investigation of forecasting the flashover parameters of High Temperature Vulcanized (HTV) silicone rubber based on environmental and polluted conditions using machine learning. The modified solid layer method based on the IEC 60507 standard was utilised to prepare samples in the laboratory. The effect of various factors including Equivalent Salt Deposit Density (ESDD), Non-soluble Salt Deposit Density (NSDD), relative humidity and ambient temperature, were investigated on arc inception voltage, flashover voltage and surface resistance. The experimental results were utilised to engineer a machine learning based intelligent system for predicting the aforementioned flashover parameters. A number of machine learning algorithms such as Artificial Neural Network (ANN), Polynomial Support Vector Machine (PSVM), Gaussian SVM (GSVM), Decision Tree (DT) and Least-Squares Boosting Ensemble (LSBE) were explored in forecasting of the flashover parameters. The prediction accuracy of the model was validated with a number of error cost functions, such as Root Mean Squared Error (RMSE), Normalized RMSE (NRMSE), Mean Absolute Percentage Error (MAPE) and R. For improved prediction accuracy, bootstrapping was used to increase the sample space. The proposed PSVM technique demonstrated the best performance accuracy compared to other machine learning models. The presented machine learning model provides promising results and demonstrates highly accurate prediction of the arc inception voltage, flashover voltage and surface resistance of silicone rubber insulators in various contaminated and humid conditions.