Investigating the influence of moisture on the 2FAL generation rate of transformers: A new model to estimate the DP of cellulosic insulation

The analysis of the concentration of furanic compounds in oil has been accepted as one of the most reliable methods to obtain information about the condition of the transformer's cellulosic insulation. In this paper, the relation between the moisture content of the paper and the rate of generation of 2-furfuraldehidyde (2FAL) is studied. A statistical study is carried out to determine if transformers with higher moisture contents in oil tend to present higher contents of 2FAL, and, to this end, a database with more than 20,000 historical records of transformers is utilized. This study is completed with a set of accelerated ageing tests of transformer cellulosic insulation pieces, conditioned with different moisture contents. The impact of the moisture content of paper on the relation between the degree of polymerization (DP) and the 2FAL concentration is determined, and a correction factor has been proposed to include this variable in a model.