The diffusion characteristics of POSS under electric field and non-uniform temperature field in natural ester insulating oil

Abstract

The natural ester insulating oil is a green and environmentally friendly liquid dielectric, and nano additives can effectively improve its dielectric and heat transfer performance. However, nano additives are prone to agglomeration, especially under the influence of electric and temperature fields, which can impact the prolonged stable operation of power transformers. In this paper, the diffusion properties of caged Polysilsesquioxane (POSS) molecules in natural ester insulating oil under external electric field and non-uniform temperature field were investigated via simulation, and the effects of temperature and electric field on POSS molecules were expounded from the perspective of interaction. The results show that the high temperature difference and strong electric field can effectively improve the mobility of POSS molecules, and the temperature difference has a greater impact on the diffusion. The decrease of interaction energy is mainly due to the negative positive interaction between Si-O molecules in POSS molecules and insulating oil at high temperature, which counteracts the attraction of branch chains. At the same time, POSS molecules in the electric field will also show obvious polarization due to temperature changes, which further reduces the interaction between POSS molecules and insulating oil molecules. In addition, the electrostatic interaction energy decreases most obviously, which is the main reason that affects the migration characteristics of POSS molecules in natural ester insulating oil. This study provides a theoretical explanation for the migration mechanism of insulating oil in the microenvironment.