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
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
Hanbo Zheng, Enchen Yang, Shuyue Wu, Weijie Lv, Hang Yang, Xufan Li, Xiaoqing Luo, Wei Hu
Summary: This article simulated the thermal aging process of cellulosic insulating paper to identify the main reaction pathways for the formation of CO2 and CO molecules, revealing that the amount of CO2 and CO generated is closely related to temperature. The study provides theoretical support for the accurate application of carbon oxides aging evaluation index at different temperatures.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2022)
Review
Green & Sustainable Science & Technology
Zijia Shen, Feipeng Wang, Zhiqing Wang, Jian Li
Summary: As mineral oil faces challenges in environmental friendliness and operational efficiency, the demand for plant-based insulating fluids as a renewable and biodegradable alternative has been increasing. With over 20 years of field experience, plant-based oils have been proven to be both cost-effective and safer than mineral oil for transformers.
RENEWABLE & SUSTAINABLE ENERGY REVIEWS
(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
Engineering, Chemical
Sherif S. M. Ghoneim
Summary: The continuity of transformer operation is crucial for maintaining power flow and revenue for utilities. Transformer failures are mainly due to the degradation of the insulating system, with DP being a key detector of insulating paper state. This research constructed a prediction model using regular tests on transformer insulating oil as predictors, and classified the DP into five classes to express the insulating paper aging rate, with decision tree proving to be the most accurate classifier with a 96.2% prediction accuracy.
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)
Article
Engineering, Electrical & Electronic
Hanbo Zheng, Xufan Li, Yongji Feng, Hang Yang, Weijie Lv
Summary: This study simulated the pyrolysis process of palm oil and found that the number of hydrogen bonds gradually increased with the increase of pyrolysis time and temperature, which revealed the reasons behind the prolonged lifespan of insulating paper immersed with natural esters and the slow reduction of breakdown voltage in actual experiments.
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)
Article
Engineering, Electrical & Electronic
Josue Rodriguez, Jose Contreras, Carlos Gaytan
Summary: This study evaluates the gas generation of a new soybean-based natural ester liquid in distribution and power transformers through lab-scale testing, and discusses predicting transformer fault types using different diagnostic methods. Results show that overheating issues in natural esters are associated with ethylene, while high energy faults and partial discharge faults are linked to acetylene and hydrogen, respectively. The Duval triangle method is confirmed as the most reliable approach for diagnosing natural ester liquids.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2021)
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)
Article
Engineering, Electrical & Electronic
Jiefeng Liu, Yiwen Luo, Heng Zhang, Chuying Liu, Xianhao Fan, Yiyi Zhang
Summary: This article investigates the effect of metal passivator BTA on the generation of methanol during the aging of insulating paper. Through molecular dynamics simulation and accelerated thermal aging experiments, it is found that the addition of BTA can promote the decomposition of insulating paper and the production of methanol. Three reaction pathways of methanol production promoted by BTA are summarized.
IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION
(2023)
Article
Chemistry, Physical
Zaid B. Siddique, Soumen Basu, Prasenjit Basak
Summary: This paper focuses on studying the dielectric behavior of a mixture of natural ester oil and mineral oil blend dispersed with TiO2 and ZnO nanoparticles. The results show an overall enhancement in the dielectric properties of nanofluids, with improved breakdown voltage compared to pure mineral oil, pure ester oil, and the oil-blend. These nanofluids can be used as insulating oils in transformers, offering better cooling performance as well.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Engineering, Electrical & Electronic
Dawei Feng, Ge Chen, Xiaoyu Yan, Jian Hao, Ruijin Liao
Summary: The study investigates the gas production characteristics of a 3-element mixed insulation oil under thermal fault through simulation and experiments, finding that the gas production of mixed oil is significantly affected by its base oils and generates more H-2 and C2H6 under thermal fault compared to mineral oil. Additionally, the study highlights the differences in gas production between mixed oil and mineral oil, with mixed oil producing higher hydrogen content and other characteristic gases under thermal fault conditions.
Article
Polymer Science
Cristina Fernandez-Diego, Alfredo Ortiz, Isidro A. Carrascal, Inmaculada Fernandez, Carlos J. Renedo
Summary: Comparing the aging of cellulose board samples immersed in mineral oil and synthetic ester, it was found that synthetic ester leads to less degradation in the insulation system. Using mechanical properties to quantify the degradation of the cellulose board through kinetic models provides information about the different behavior exhibited by PSP 3055 with different fiber direction angles considered.
