Combustion Characteristics and Self‐Extinguishing Mechanism of Novel Self‐Extinguishing Fluorinated Silicone Insulating Oil

ABSTRACT Traditional mineral oil has long served as a liquid insulating medium in power transformers. However, its low fire resistance, poor biodegradability and dependence on finite fossil fuel resources, along with its low flash point, contribute to transformer explosions and fires. To overcome these limitations, developing insulating liquids with high flash points and self‐extinguishing properties is essential. Although natural ester‐based insulating oils and silicone oils have been proposed as alternatives, their performance requires further optimisation, and their application in transformers remains challenging. This study examines the combustion characteristics of three novel self‐extinguishing fluorinated silicone oils using combustion experiments and reactive molecular dynamics simulations. The results demonstrate that methylfluorinated and hydrofluorinated silicone oils exhibit superior self‐extinguishing performance compared to mineral oil and natural ester‐based insulating oils. Simulation analyses indicate that fluorinated silicone oils generate silicon‐oxygen polymers upon ignition, which influence subsequent chain reactions. However, hydroxyfluorinated silicone oil releases a higher concentration of key free radicals, intensifying chain reactions and diminishing its self‐extinguishing capability. As a result, its self‐extinguishing performance is significantly weaker than that of methylfluorinated and hydrofluorinated silicone oils. These findings provide valuable insights for the development of advanced liquid insulating media as potential replacements for mineral oil.