Article
Energy & Fuels
Tobias Muenster, Peter Werle, Kai Haemel, Joerg Preusel
Summary: The article discusses the aging behavior of oil-paper insulations in transformers using different insulating fluids and highlights differences in aging rates and marker formations among mineral oil and ester-based insulating fluids, which can enhance asset management strategies.
Article
Engineering, Electrical & Electronic
Ed Casserly, Juan Acosta, Andy Holden, Brad Greaves, Tom Prevost
Summary: The thermal index of thermally upgraded Kraft paper was determined using IEEE Standard C57.100 Annex A.4.2 for five mineral insulating liquids and two natural esters, and compared with the values in IEEE Standard C57.91.
IEEE ELECTRICAL INSULATION MAGAZINE
(2022)
Article
Green & Sustainable Science & Technology
Jinshan Qin, Xiao Peng, Qinpan Qiu, Chao Tang
Summary: This paper investigates the mechanism of improving the properties of natural ester insulating oil by modifying it with nano hexagonal boron nitride grafted with silane coupling agent (APTES-hBN). Experimental results show that the addition of Nano APTES-hBN inhibits acid production and reduces the number of polar molecules in the oil. Mechanism study reveals that the addition of Nano APTES-hBN enhances the interfacial bonding between oil and paper insulation, and has strong adsorption capacity.
Article
Engineering, Electrical & Electronic
S. S. Kumaresh, M. Malleswaran
Summary: This paper predicts the aging state of oil impregnated insulating Kraft paper using textural properties. A new accelerated aging kit is developed for experiments, and supervised and unsupervised machine intelligence methods are trained to classify images based on features. The study shows that this machine intelligence-based methodology is effective in classifying the aging state of Kraft Insulating Paper.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Review
Engineering, Electrical & Electronic
Marina N. Lyutikova, Sergey M. Korobeynikov, U. Mohan Rao, Issouf Fofana
Summary: Due to growing environmental concerns, synthetic and natural esters have become the focus for high-voltage equipment insulation in the past two decades. These ester liquids are biodegradable, non-toxic, safe for the environment and human health, and derived from renewable sources with high fire resistance. However, their use is limited in electrical equipment due to factors such as high cost, viscosity and density, electrostatic charge, and faster propagation of streamers in an inhomogeneous electric field. This article presents a comprehensive review on the blend of mineral oil and alternative dielectric fluids, discussing research progress, challenges, and tutorial elements. This is valuable for researchers, utilities, and transformer owners concerned with ester liquids and retrofilling.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Helena M. Wilhelm, Paulo Fernandes, Kethlyn Moscon Paulo Fernandes, Mayara Fornari, Sergio Peres, Vitor Bender, Tiago Marchesan, Richard Marek, Germano Moraes, Nelson Veloso, Luan Martins, Marco Marin
Summary: The performance of a new insulating oil/paper system was evaluated using accelerated ageing tests. The degree of polymerization (DP) and tensile strength of two insulating papers, hybrid paper (HP) and thermally upgraded kraft paper (TUK), were determined. A natural ester insulating oil (NEIO), made from soybean, was used. The degradation of insulating liquids depended on the paper type, with HP showing the least negative effect.
2023 IEEE ELECTRICAL INSULATION CONFERENCE, EIC
(2023)
Article
Engineering, Electrical & Electronic
Shuhang Shen, Qiang Liu, Zhongdong Wang
Summary: The experimental study focused on analyzing the spatial characteristics of Mach-cone shaped shockwaves generated by streamers in mineral oil and synthetic ester. The results showed that the appearance of Mach-cone shaped shockwave is an effective indicator of actively propagating streamer channel. Voltage levels did not have a significant impact on the observed shockwave parameters.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
Article
Engineering, Multidisciplinary
Joyce Jacob, P. Preetha, T. K. Sindhu, U. Mohan Rao
Summary: In this study, it is found that natural ester nanofluids exhibit better dielectric and thermal properties compared to non-biodegradable mineral oil. After 1200 hours of thermal aging, the AC breakdown voltage, thermal conductivity, and tensile strength of cellulose impregnated with natural ester are significantly higher than those impregnated with mineral oil. Furthermore, the AC breakdown voltage, thermal conductivity, and tensile strength of cellulose impregnated with natural ester nanofluid are also higher than those impregnated with mineral oil nanofluid. These findings suggest a potential for extended service life of solid insulation in liquid filled high voltage transformers.
Article
Chemistry, Physical
Wenyu Ye, Jian Hao, Chenyu Gao, Qing Xu, Mengzhao Zhu, Ruijin Liao
Summary: This study investigates the molecular details about the dynamic behavior of hydrocarbons and ester insulating liquids on the surface of crystalline cellulose. The comparisons of microscopic differences between the two insulating liquids and cellulose interfaces provide insights into the development of environmentally friendly insulating materials. The theoretical basis provided in the study supports the more scientific application of natural esters in oil-immersed power transformers.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Proceedings Paper
Engineering, Electrical & Electronic
Brad Greaves, Thomas Prevost, Ed Casserly, Juan Acosta, Andy Holden
Summary: Accelerated aging studies are used to determine the thermal class of insulation systems, with tests completed according to IEEE C57.100. Candidate systems must undergo accelerated aging at a minimum of three temperatures for evaluation, which can significantly impact the thermal index calculation results.
2021 IEEE ELECTRICAL INSULATION CONFERENCE (EIC)
(2021)
Article
Energy & Fuels
Maciej Zdanowski
Summary: This paper presents research results on the use of fullerene C-60 to reduce the phenomenon of streaming electrification generated by liquid dielectrics. The influence of flow velocity and C-60 concentration on the electrification of different liquids was analyzed, and the optimal concentration of C-60 resulting in the highest reduction of the electrification phenomenon was identified.
Proceedings Paper
Energy & Fuels
Abdelrahman M. Alshehawy, Shanika Matharage, Zhongdong Wang
Summary: This study investigates the space charge behavior of insulation systems with paper and synthetic ester as potential candidates for HVDC transformers. The results show that the charge density and accumulated charges in the paper insulation increase at the early stage of ageing but later decrease to a similar level as new paper samples.
2022 9TH INTERNATIONAL CONFERENCE ON CONDITION MONITORING AND DIAGNOSIS (CMD)
(2022)
Article
Optics
Wang Liang, Qi Zhipeng, Li Ze, Guo Li
Summary: This paper investigated the thermal aging of FR3 insulating oil and the influence of moisture content on its terahertz optical parameters. The results showed that the optical parameters increased with aging degree, and moisture was identified as the main factor affecting the terahertz optical parameters of insulating oil.
Article
Materials Science, Paper & Wood
Chengen Li, Lu Yang, Zuhao Wang, Chao Tang
Summary: Nano-modified insulating paper, doped with octaaminophenyl-POSS (OAPS) nanoparticles, showed improved tensile strength and reduced relative dielectric constant. After accelerated thermal aging, the OAPS-modified insulating paper exhibited higher tensile strength and lower dielectric constant compared to the unmodified sample. Molecular dynamics simulation revealed that OAPS forms hydrogen bonds with cellulose chains, inhibiting their movement and polarizability.
Article
Polymer Science
Draginja Mihajlovic, Valentina Vasovic, Jelena Lukic
Summary: The aim of this study is to propose a test method for the determination of the quality of transformer paper insulation. The aging experiments conducted on normal Kraft and thermally upgraded papers, two different types of transformer oils, and copper showed that aging of cellulose insulation in cycles was 1.5-1.6 times faster than continuous aging. The proposed aging test in cycles can be used to achieve faster aging and to compare the quality of different insulating papers.
