Characteristics of Split-Phase Currents as a Source of Generator Protection [includes discussion]

As split-phase currents are the difference between two large load currents in theoretical balance, they exist only because necessary manufacturing tolerances prevent the attainment of theoretical balance, or because of winding faults. A rigorous treatment of the subject is not possible: this paper is therefore in the nature of a report of numerous tests that have been made to evaluate the nature and relative difference of these currents, as they may exist due to machine construction, external faults, and internal faults. It is supplemented with some data in respect to transformers and relays associated with the protective equipment.