Experimental Study on Transformer Oil Pool Fire Suppression by Water Mist

Abstract

Oil-insulated transformer is the main source of power substation fire. It is important therefore to investigate the fire suppression of transformer oil pool fires. Experiments were conducted in a 3 × 3 × 3 m room to study the transformer oil pool fire suppression by water mist. The square pool fire with dimensions of 17, 25, and 30 cm and a downward-directed single-injector nozzle with operating pressures of 1.0, 2.5, and 4 MPa were considered in the experiments. The flame shape during water mist application was recorded by a video camera. The temperature, CO concentration, and flame thermal radiation were measured to evaluate the fire suppression process by water mist. The results show that the flame would be intensified due to the injection of water mist at the initial period, and the intensification phenomenon is related to the fire size and the injection pressure of water mist system. The flame intensification occurred obviously under low injection pressure and large-size fire conditions. In addition, the fire extinguishment time increases with the decrease of the injection pressure and the increase of pool size. The results of this work would be valuable for optimizing the water mist system in the application of transformer substation fire suppression.