generator testing

          A 500 MW generator failed catastrophically, it had an internal short that resulted in a phase to phase short. The generator stopped so suddenly that it sheared off 24 2 ½” bolts in the coupling between the generator and the turbine. The problem was traced to the phase leads resonance shifting to 120HZ as the generator aged. This problem resulted in the annual testing of the phase leads for the unit that had the failure and also on its sister machine. One of the key lessons learned during many hours of testing these generators was that [...]