Heat release rate of vertical combustibles inside a confinement : an analytical approach to the fire of electrical cabinets
S. Melis, L. Rigollet. Conférence INTERFLAM 2004
Fire in electrical cabinets is a major concern for the nuclear safety because it is a risk which may lead to severe consequences in power plants. Published data on fires in electrical cabinets are scarce or not easily applicable for another configuration of electrical cabinet. An experimental program in two stages is defined in order to characterize the main phenomena governing a fire in an electrical cabinet. The first step is an analytical approach: the electrical cabinet is simulated by a steel box in which electrical components are represented by variable amounts of fuel squares, set in a vertical plate configuration. Several parameters are studied : the size and the location of the ventilation opening, and the composition of the combustible. The second stage aims to check the relevance of the analytical approach. It consists in carrying out two tests involving real electrical cabinets. All experiments are carried out beneath a hood in order to measure the heat release rate (HRR) by using the oxygen consumption principle. A phenomenological description of the fire is given : an incubation stage, a faster growth stage, a stage of outside combustion, a steady stage and a decay stage are distinguished. An analysis of experimental results confirms the key role of the ventilation conditions ; the steady HRR stage can be successfully described with the post-flashover compartment theory. The influence on the fire growth of the ventilation conditions and of the composition of the fuel is qualitatively identified.
Complementary investigations are foreseen to fully predict the development of the fire in an electrical cabinet