Energization of a 3000 rpm, 2 pole generator with field applied at other rotor speed is in effect an out-of-phase synchronization. The severity of this event is dependent on the speed differential, the angular difference between the generator and system, and system stiffness. Shaft torsional excursions in excess of three times rated can occur as a result of a three-phase event. The torsional oscillation from such an event can persist for 30 sec with each individual torsional excursion adding to the total loss of fatigue life in the shaft.