Abstract: Based on causes of oil spill fires in transformers,a series of small - scale experiments on compressed air foam extinguishing whole - surface spill fires in transformers were studied.With compressed air foam sprinkler system and foam gun,two types of fire extinguishing methods were applied.The advantage and variation rule of extinguishing whole - surface oil spill fires in transformers with compressed air foam were evaluated. The study showed that the film - formed compressed air foam was effective in extinguishing whole - surface oil spill fires in transformers.It could form a stable coating on the high - temperature oil surface to prevent boiling and splashing.Cooling was the key factor for extinguishing fire.It could extinguish whole - surface oil spill fires in transformers and prevent re - ignition by cooling the oil temperature below the ignition point.

Key words: oil - immersed transformer;whole - surface, compressed air foam;spill fire