Hydro Electric Generator FEA Analysis Ryan MacTarnaghan Mechanical Engineer Department of Water Resources

Failure of a Generator Coupler  Premature Opening of the Discharge Valve The valve is opened before discharge pressure is high enough resulting in reverse water flow The valve is opened before discharge pressure is high enough resulting in reverse water flow  Putting on out of Sync Motor into Synchronous Mode The motor is directly placed on the electric grid while out of phase resulting in large instantaneous forces at the coupler The motor is directly placed on the electric grid while out of phase resulting in large instantaneous forces at the coupler

Motor and Upper Shaft

Turbine and Lower Shaft

Coupler

Failure Mode  Opposing torque between upper and lower shaft  High torque leads to shearing of the bolts at the coupler

FEA Analysis

Results  Due to the symmetry of the application the FEA only needs to be performed on one bolt  The drawing shows the greatest stress at the mating surface of the coupler and can be used to predict the failure of the bolts.