Biodegradable Oils and their Impact on Paper Ageing

Mineral oils are still the preferred choice for insulation and cooling purposes in liquid‐filled transformers due to their low cost and excellent dielectric properties. This chapter provides a better understanding of the chemistry of biodegradable oil, including chemical composition and degradation mechanisms. It discusses the application of existing chemical and electrical‐based condition monitoring tools for biodegradable oil‐filled transformers. It summarizes the results of some laboratory investigations into 2‐furfural (2‐FAL) analysis of ester‐based insulation systems. The chapter presents three case studies to enhance the understanding of gassing behavior of different insulating oils. The use of a Dissolved Gas Analysis (DGA) interpretation scheme for ester insulation is also discussed. The case studies presented in the chapter underline the requirement for revisions of international standards used for quality assurance of mineral insulating oil to comply with ageing and gassing behavior of ester insulating oils.