Effects of conductivity and permittivity of nanoparticle on transformer oil insulation performance: experiment and theory

• Published in: IEEE transactions on dielectrics and electrical insulation Vol. 22; no. 1; pp. 380 - 390
• Main Authors: Sima, Wenxia, Shi, Jian, Yang, Qing, Huang, Sisi, Cao, Xuefei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2015; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Conductivity; Dielectrics; Electric fields; Electric potential; nanoparticle; Oil insulation; Permittivity; potential well; Power transformer insulation; streamer
• ISSN: 1070-9878; 1558-4135
• DOI: 10.1109/TDEI.2014.004277

The mechanisms by which conductive and dielectric nanoparticles (NPs) trap electrons are explained by the potential well distribution caused by induced or polarized charges on NPs. Thus, the distributions of surface and saturation charges on conductive and dielectric NPs are determined. Given conductive Fe 3 O 4 , semiconductive TiO 2 , and dielectric Al 2 O 3 NPs, insulation performance tests are conducted and ionization models of nanofluids (NFs) based on transformer oil are developed. These models are compared with those of NFs based on pure oil. The NP whose conductivity or permittivity does not match that of the dielectric liquid has a potential well and an increased amount of saturation charges on its interface. This NP influences streamer development strongly and enhances the breakdown of oil-based NF.