Loss and recovery of synchronism of parallel alternators

THIS CASE OF operating trouble is both interesting and instructive from a generating station point of view because the graphic record of the electric energy disturbance is complete. The description deals specifically with the in-step and out-of-step relationships of the generator rotor poles to the rotating magnetic poles produced by currents flowing in the stator windings during normal conditions and during the abnormal condition brought about by underexcitation.