Role of Micro and Nanofi llers in Electrical Tree Initiation and Propagation in Cross-Linked Polyethylene Composites

Ashish Paramane,Kannaiah Sathish Kumar 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.4

Electrical treeing is a pre-breakdown phenomenon responsible for the long-term degradation and failure of polymericelectrical insulation. This paper presents a study of electrical treeing in unfi lled crosslinked polyethylene (XLPE), XLPEmicrocomposites (30, 40, and 50 wt% microsilica), and nanocomposites (1, 2, 3, 4, 5, and 10 wt% nanosilica) at an appliedvoltage of 12 kV. The XLPE nanocomposites show signifi cant increase in electrical tree initiation and breakdown timescompared to the microcomposites and unfi lled XLPE. Notably, the 5 wt% nanocomposite shows the longest initiation andbreakdown times and the least tree growth. The novelty of this study lies in the identifi cation of nanosilica in the electricaltree channels via scanning electron microscopy. The role of micro and nanosilicas in electrical tree initiation and propagationis explained theoretically.

Characterization of a Functional Coating Film Synthesized on the Ceramic Substrate for Electrical Insulator Application according to Coating Method

Shan, Bowen,Kang, Hyunil,Choi, Wonseok,Kim, Jung Hyun The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.3

For the improvement of the anti-fouling features of porcelain electrical insulators, in this study, the surface of an insulator was coated with a functional material to expand the insulator's self-cleanness. The anti-fouling and mechanical features of the functional film coating of ceramic substrates made from components like an electrical insulator were analyzed. The coating methods that were used were spray coating, dip coating, and fabric coating. Following the coating, the contact angle of the coated surface was measured, revealing that the spray coating method offered the lowest angle ($13.7^{\circ}$) and a strong hydrophilic feature. The anti-fouling analysis showed that the anti-fouling features improved as the contact angle decreased. The mechanical properties - hardness and adhesion - were both excellent at 9H and 5B, respectively, regardless of the coating method that was used.

장간유리애자 파손시 절연파괴 특성

鄭鍾旭(Jong-Wook Jung),鄭鎭洙(Jin-Soo Jung),金榮錫(Young-Seok Kim) 대한전기학회 2008 전기학회논문지 Vol.57 No.8

This paper describes the electrical breakdown characteristics of broken toughened glass stem insulators by comparing with those of sound ones. The broken roughened glass stem insulators were taken from the electric railway field. According to the international standards, the sound and broken toughened glass stem insulators were tested in electrical strength. In the test, the power frequency voltage and the impulse voltage with a standard waveform were applied to the insulators. The power frequency voltage tests were carried out under both dry and wet condition and the impulse voltage tests under only dry condition. The acquired results were compared one another and discussed in electrical breakdown characteristic by analyzing the flashover progress pictures. As a result, the electrical strength of the broken toughened glass insulators was acquired and the processes of the surface breakdown on the toughened glass insulators were confirmed.

Aging effect analysis of long period operating composite insulators in different electric field position

Yun-Peng Liu 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.S1

Electric field distribution is one of the important factors which impact the aging of composite insulators. The electric field of composite insulators was simulated by ANSYS software, and the shed samples in different parts of the composite insulator were analyzed by Fourier transform infrared spectroscopy (FTIR). The characteristic peaks of functional groups in the main chain and side chain of composite insulator material molecular formula were compared. The smaller the characteristic peak area is, the less the corresponding functional group is, that means the facture condition of main chain or side chain is more serious. In this way, the characteristic peaks of samples in different electric field distribution were compared, and the influence of electric field distribution to the aging effect of the composite insulators is gained. The results show that electric field strength is the strongest in the composite insulator high-voltage side, followed by lowvoltage side, and the electric field in the middle of the composite insulator is the lowest. Accordingly, the aging degree in the composite insulator high-voltage side is the most serious, followed by low-voltage side, and the aging degree is weakest in the middle part.

자기재/폴리머 계면이 하이브리드 애자의 미세구조, 절연특성과 전계분포에 미치는 영향

조준영,김우석,안호성,안희성,김태완,임윤석,배성환,박찬,Cho, Jun-Young,Kim, Woo-Seok,An, Ho-Sung,An, Hee-Sung,Kim, Tae-wan,Lim, Yun-Seog,Bae, Sung-Hwan,Park, Chan 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.9

Hybrid insulators that have the advantages of both porcelain (high mechanical strength and chemical stability) as well as polymer (light weight and high resistance to pollution) insulators, can be used in place of individual porcelain and polymer insulators that are used for both mechanical support as well as electrical insulation of overhead power transmission lines. The most significant feature of hybrid insulators is the presence of porcelain/polymer interfaces where the porcelain and polymer are physically bonded. Individual porcelain and polymer insulators do not have such porcelain/polymer interfaces. Although the interface is expected to affect the mechanical/electrical properties of the hybrid insulator, systematic studies of the adhesion properties at the porcelain/polymer interface and the effect of the interface on the insulation characteristics and electric field distribution of the hybrid insulator have not been reported. In this study, we fabricated small hybrid insulator specimens with various types of interfaces and investigated the effect of the porcelain/polymer interface on the microstructure, insulating characteristics, and electric field distribution of the hybrid insulators. It was observed that the porcelain/polymer interface of the hybrid insulator does not have a significant effect on the insulating characteristics and electric field distribution, and the hybrid insulator can exhibit electrical insulating properties that are similar or superior to those of individual porcelain and polymer insulators.

Surface Discharge Characteristics Study on the Laminated Solid Insulator in Quasi-Uniform Electric Field with Dry Air

Min, Gyeong-Jun,Bae, Sungwoo,Kang, Byoung-Chil,Park, Won-Zoo The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.2

Dry air is an excellent alternative to $SF_6$ gas and is used as an insulation gas in Eco-friendly Gas Insulated Switchgears (EGISs), which has gained popularity in industry. Solid insulators in EGIS play an important role in electrical insulation. On the other hand, surface discharge can occur easily when solid insulators are used. This paper explored the surface discharge characteristics on the structure of three-layered laminated solid insulators to elevate the flashover voltage. A laminated solid insulator was inserted after the quasi-uniform electric field was formed in the test chamber. Dry air was then injected to set the internal pressure to 1 ~ 6 atm, and the AC voltage was applied. When identical solid insulators were stacked, the surface discharge characteristics were similar to those of a single solid insulator. On the other hand, the flashover voltage rose when the middle part was thicker and had lower permittivity than the top and bottom parts in the laminated solid insulator. Based on experimental results, when stacking a solid insulator in three layers, the middle part of the solid insulator should be at least four times as thick as the top and bottom parts and have lower permittivity than the others. In addition, the flashover voltage increased with increasing gas pressure on the surface of the laminated solid insulator due to the gas effect. This study may allow insulation design engineers to have useful information when using dry air for the insulation gas where the surface discharge can occur.

The Study on Weibull Failure Models for Oil Gap–Paper Insulation Under Pulsating DC Voltage with Temperature

Jiang Tianyan,Deng Biao,He Qiaoqing,Bi Maoqiang,Chen Xi,Bao Lianwei,Zhou Xin 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

This paper presents Weibull failure models by experimental work and the step-up accelerated electrical–thermal test of oil-impregnated paper with 0.2 mm thickness is carried out under pulsating DC voltage at different temperatures. The breakdown voltage and failure time of the oil gap–paper insulation specimens at the same voltage duration is obtained by accelerated electrical–thermal aging test. The Weibull failure models of three-variable oil gap–paper insulation modified by Fallou and Ramu are established to analyze the failure data of oil gap–paper under different electric field intensities and temperatures. The statistical test method was used to evaluate the applicability and accuracy of two modified triple-variables Weibull failure models. The comprehensive test index of the Fallou-modified WFD is 1.6851, and the comprehensive test index of the Ramu-modified WFD is 1.8124. The Fallou-modified results were more accurate than Ramu-modified results in estimating the statistical distribution of failure data. Results show that the proposed triple-variable Weibull failure model could fully reflect the insulation state of oil gap–paper under the action of electric and thermal fields.

Tensile and Electrical Insulation Properties of Epoxy/Micro‑silica Composites

박재준 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.1

The effect of epoxy species on the tensile and electrical insulation properties of epoxy/micro-silica composites was studied by using three species of epoxy resins for high voltage insulators. The mixing ratio of spherical type micro-silica was varied at 40–70 wt% in each epoxy systems. Tensile strength of three Epoxy/micro-silica composites was lower than that of the each neat epoxy system and increased with increasing micro-silica content in each system. The maximum tensile strength was 86.0 MPa in Epoxy 2/micro-silica (70 wt%) composite. Electrical insulation breakdown strength of three Epoxy 1/micro-silica, Epoxy 2/micro-silica, Epoxy 3/micro-silica composites was higher than that of the each neat Epoxy 1, Epoxy 2 and Epoxy 3. The maximum electrical insulation breakdown strength was 55 kV/2mm in Epoxy 2/micro-silica (50 wt%) composite.

Effect of Organically Modified Layered Silicate on Thermal, Mechanical, and Electrical Properties of Epoxy-Based Nanocomposites

박재준,Soon-Seok Kwon,이재영 한국전기전자재료학회 2011 Transactions on Electrical and Electronic Material Vol.12 No.4

In an effort to develop new electrical insulation materials, four different kinds of organically modified layered silicate were incorporated into an epoxy matrix to prepare nanocomposites for electrical insulation. Five wt% of organically modified layered silicates were processed in a planetary centrifugal mixer in an epoxy matrix, and the thermal,mechanical, and electrical properties of the cured epoxy/layered silicate were investigated. The morphology of the nanoscale silicate dispersed in the epoxy matrix was observed using transmission electron microscopy, and the interlayer distance was measured by wide-angle X-ray scattering diffraction analysis.

Effect of Organically Modified Layered Silicate on Thermal, Mechanical, and Electrical Properties of Epoxy-Based Nanocomposites

Park, Jae-Jun,Kwon, Soon-Seok,Lee, Jae-Young The Korean Institute of Electrical and Electronic 2011 Transactions on Electrical and Electronic Material Vol.12 No.4

In an effort to develop new electrical insulation materials, four different kinds of organically modified layered silicate were incorporated into an epoxy matrix to prepare nanocomposites for electrical insulation. Five wt% of organically modified layered silicates were processed in a planetary centrifugal mixer in an epoxy matrix, and the thermal, mechanical, and electrical properties of the cured epoxy/layered silicate were investigated. The morphology of the nanoscale silicate dispersed in the epoxy matrix was observed using transmission electron microscopy, and the interlayer distance was measured by wide-angle X-ray scattering diffraction analysis.