Reclamation Information Sharing Environment (RISE)

This study evaluates hybrid water-mist/inert-gas fire suppression as a safer alternative to carbon dioxide (CO2) for protecting hydroelectric generators greater than 10-megawatts. Using a 1950’s 16 megawatt, 6.9 kilovolt generator, we induced controlled turn-to-turn stator faults to compare a temporary CO2 system with a Victaulic Vortex (TM) hybrid system under realistic operating conditions. Instrumentation measured oxygen concentration, temperatures, and electrical parameters; post-event testing assessed stator and field insulation per Institute of Electrical and Electronics Engineers (IEEE) 43. Hybrid discharges rapidly reduced oxygen concentrations from normal to approximately 11% per volume and cooled the combustion zone, extinguishing flames, suppressing smoldering, and preventing re-ignition. CO2 achieved faster oxygen reduction by design but faced delivery issues in testing. Hybrid exposure produced measurable yet acceptable insultation resistance and polarization index reductions; all values remained above IEEE thresholds. Results indicate hybrid systems can match or outperform CO2 in effectiveness while eliminating personnel hazards, supporting their adoption within integrated detection and relay protection schemes.