Abstract: The suppression effectiveness of superfine powder extinguishing equipment for transformer oil fire under different conditions was studied through a series of fire suppression experiments with 1 m2 transformer oil fire, and the technical feasibility of applying the superfine powder extinguishing equipment on oil-immersed transformer was also analyzed. The results show that the 4 kg superfine powder extinguishing equipment can quickly and effectively extinguish the oil-immersed transformer initial fire with base oil temperature not more than 155 ℃ and preburning time not more than 5 min，so that it does not reignite. The results also show that the preburning time significantly affects whether the transformer oil fire will reignite, and the transformer oil fire will reignite after extinguished by superfine powder when the preburning time exceeds 10 min. The results prove that it is technically feasible to use the superfine powder extinguishing equipment to extinguish the initial fire of oil-immersed transformer. It is suggested that the suitable distance between the outlet of superfine powder extinguishing equipment and the key part of oil-immersed transformer is 1.7~2.0 m in practical engineering.

Key words: superfine powder; extinguishing equipment; oil-immersed transformer; fire