Swan Falls Unit #1 Failure,Root Cause Investigation, and Re-Design

摘要

Swan Falls Powerplant is a two-unit plant operational since 1994. On May 23, 1998 aline fault caused an emergency shutdown. Unit #2 shut down as expected, but Unit #1experienced an extended runaway condition and ultimately major mechanical damage.The Swan Falls machine train consists of horizontal pit units comprised of 4 bladedKaplan turbines with a planetary gearbox coupled between the generator and turbine.Major damage to the turbine and wicket gate assembly with lesser damage to theplanetary gearbox occurred. The turbine and wicket gates were refurbished and gearswithin the gearbox were replaced. Disassembly, root cause investigation, componentrefurbishment or remanufacture, and reassembly spanned a two-year period. Thispaper discusses damage incurred to the machine train, identifies the causes of thefailure, and explains the steps taken to prevent a similar failure in the future.