Leakage current value when extinguishing live electrical equipment by automatic gas and water fire suppression systems

Abstract

PURPOSE. The article studies the issue of extinguishing live electrical equipment by means of automatic fire suppression systems (AFSS). The purpose of the work is to assess the possibility of personnel’s safe use of various types of automatic fire suppression systems when extinguishing live electrical equipment at power facilities. The authors analyze the statistics of transformer substation and cable duct fires in the Russian Federation within the period from 2018 to 2021 and regulations in the field of application of automatic fire suppression systems for extinguishing fires of live electrical equipment. A series of experiments was carried out to determine the leakage current when a fire extinguishing agent is supplied from AFSS to energized equipment. METHODS. To study the possibility of using AFSS in case of fires of live electrical equipment at power facilities, methods of analysis and experiment are used. FINDINGS. The first series of experiments was carried out on an automatic gas fire suppression system using halon 125 as a fire extinguishing agent. Extinction of B1 simulated fire sources filled with n-heptane was carried out. Over the whole experiment on the hand-operated starting device of the automatic system leakage current did not exceed the threshold non-perceptible value of 0.5 mA. The second series of experiments was carried out on a water spray automatic fire suppression system. The large spray angle of the nozzles prevented the entire amount of fire extinguishing agent from reaching the standard target; therefore, in order to obtain more accurate data, a new target sized 3 000×3,000 mm was manufactured. Spray nozzles with different k-factor values were investigated. The experiment made it possible to determine the values of leakage current on a pump unit body and spray nozzle. RESEARCH APPLICATION FIELD. The obtained experimental data indicate the possibility of safe use of water spray and gas automatic fire suppression systems to extinguish live electrical equipment. CONCLUSIONS. The results of the study can provide a substantiation for measures that exclude electric shock to facility personnel in case of using automatic fire suppression systems when extinguishing live electrical equipment.