Figures 11 and 12 show that a similar ferroresonance condition can occur for grounded and ungrounded-wye connections of the iron cores. With the grounded-wye connection of the windings, an unbalanced switching condition
provides series resonance paths including the nonlinear cores and the phase-to-phase capacitances, Figure 11. A delta-connected power factor correction capacitor can complete the condition for the ferroresonance. If the windings form an
ungrounded-wye, the shunt capacitances provide series ferroresonance paths under unbalanced switching conditions, as shown in Figure 12.