An extension of the method of symmetrical components using ladder networks

IN his now classical paper on symmetrical components Fortescue analyzed the behavior of synchronous and induction machinesoperating under unbalanced conditions. In this analysis Fortescue assumed that the stator and rotor windings themselves were symmetrical, that the rotor windings were either short-circuited or connected to balanced static circuits, and that the stator windings were connected to unbalanced circuits. Under these conditions there are unbalanced currents of a single frequency in the stator, and balanced currents of two different frequencies in the rotor. It has since been shown how the method of symmetrical components is applied when the rotor windings are connected to unbalanced circuits and the stator windings are connected to balanced circuits. Under these conditions there are unbalanced currents of a single frequency in the rotor, and balanced currents of two different frequencies in the stator.