Abstract: In order to understand the deflagration risk of transformer oil indepth,the deflagration characteristic of 45# fresh and waste transformer oil was studied by combustible gas/vapor explosion test system and flammable liquid droplet deflagration test system. The results showed that as the temperature rises from 115 ℃ to 150 ℃ , the lower explosion limit of oil gas decrease, and the risk of deflagration increases; When the temperature is constant, as the injection pressure rises from 0.8 MPa to 2.4 MPa,the particle size of oil droplet decreases, the duration of deflagration increases, and the risk of deflagrationupgrades;The deflagration risk of fresh transformer oil is greater.

Key words: transformer oil, lower explosion limit, oil mist particle size, injection pressure