Reestablishing Excitation of a Loaded Alternator in Parallel with Others

The paper describes operating tests with large turbo generators under load and gives a résumé of answers to a questionnaire, bearing on the phenomena accompanying the interruption of the direct-current excitation supply, followed by reclosing after a short interval. The object of the investigation was to determine, if possible, a reasonably safe operating procedure that could be followed in reestablishing normal conditions on a large turbo generator whose excitation had been interrupted while carrying load. The authors conclude that the reexcitation of a generator without withdrawing it from the bus is a justifiable and safe operating procedure and the one that will restore all conditions to normal in the shortest time. These conclusions have been verified by twelve prearranged tests, five ``experiences'' in the local company and seventeen ``experiences'' by other companies. In all of these cases the field switches have been reclosed without trouble of any kind.