Research on suppression effectiveness of compressed air foam for oil-immersed transformer hot oil fire

Abstract

Transformers, being the largest oil-bearing equipment, are susceptible to high-temperature hot oil fires and large-area flowing fires that can be challenging to extinguish. To investigate the effectiveness of compressed air foams (CAFs) agents in extinguishing fires in ultra-high voltage (UHV) converter transformers, this work examines the fire suppression capabilities of three typical CAFs agents. A test model of a hot oil fire in a transformer with a burning area of 1 m2 was constructed for this purpose. The fire test was conducted by heating the transformer oil using an electric heating system, and the test process was monitored using an unmanned aerial vehicle. The results indicate that three CAFs agents used in the tests are capable of extinguishing a 1 m2 transformer hot oil fire without causing boiling over phenomenon. 1% MJBP CAFs is the fastest with a fire extinguishing time of 168 s, and is even more efficient when the gas to liquid ratio is 9:1. CAFs have the advantage of uniformity and stability, making it suitable for extinguishing hot oil fires in extra high voltage transformers as it does not cause boiling fires during firefighting.