Studying the Loss of Life of Natural-Ester-Filled Transformer Insulation: Impact of Moisture on the Aging Rate of Paper

Moisture is one of the most harmful agents for transformer solid insulation. The catalyzing effect of moisture on the degradation process of paper and pressboard has been studied by several authors, who developed models which they used to estimate how the aging process would be accelerated in the presence of water [1]-[5]. In [2] and [3] Lelekakis et al. reported the results of an experimental study in which samples with different moisture contents were aged in the presence of mineral oil (MO). In [3] an equation to determine the reduction of service lifetime of insulation subjected to increased temperature and with increased moisture content is proposed.This work was supported by the Ministry of Economy and Competitiveness of Spain through the projects DPI2012-35819 and DPI2015-71219-C2-2-R, and by CEIS (Centro de Ensayos Innovación y Servicios). The authors acknowledge advice from María Zabalegui of CEIS, and the contribution of Javier González to this work during his master's thesis candidature.Publicad