Effects of Corrosion Factors on Sulphur Corrosion Activity in Transformer Insulating Oil Using Two-Level Factorial Design

The issue of sulphur corrosion in transformer insulating oils has been a significant problem for several decades, primarily due to the increasing incidence of power transformer failures. The longevity of power transformers may be reduced due to their reliance on the oil-paper insulation, which can deteriorate due to sulphur corrosion. The formation and deposition of copper sulphide can lead to transformer failures, which is of great concern to manufacturers and operators of power transformers. Nevertheless, there is a lack of extensive studies that systematically investigate the effects of corrosion-related variables on both the dissolution of copper in transformer insulating oil and the accumulation of copper sulphide on the surface of the solid insulation, including kraft paper. This study is carried out to investigate the effects of three factors (oil temperature, elemental sulphur concentration, and ageing period) on the sulphur corrosion activity of transformer insulating oil by using two-level factorial design. The results indicate that oil temperature is the factor that significantly influences the surface resistivity of the kraft paper, with a percentage contribution of 26.09%. A regression model is also developed to predict the surface resistivity of kraft paper as a function of the oil temperature, elemental sulphur concentration, ageing period, and the interactions between these factors, which will be beneficial to users investigating sulphur corrosion in transformer insulating oils.