Abstract: Against the problem of steam cloud explosion accident caused by UHV transformer fire, combined with an UHV transformer deflagration accident, a full-scale UHV transformer model was established using FLACS to simulate two working conditions: the first steam cloud explosion of the transformer and the explosion after the steam cloud fully expanded, and the explosion damage range was decided. It is found that the maximum pressure of the first steam cloud explosion is 7.2 kPa, which is concentrated on the upper part of the oil tank and mainly destroys the upper structure of the oil tank. For the second steam cloud explosion, the maximum pressure is 26.7 kPa, and the pressure is concentrated around the entire transformer, and the transformer is destroyed as a whole. According to the result of explosion simulation, the automatic fire extinguishing system can be reasonably arranged and the damage to the automatic fire extinguishing system can be reduced.

Key words: fire protection, UHV transformer, vapor clouds explode, FLACS