In the time of 1 s, when Grand Rapids station is changed to
generator mode, the magnitudes of voltage and current are
decreased. The magnitude of harmonic and T.H.D (161 %) are
decreased subsequently. Frequency varies irregularly from 60
to 95 Hz. It is concluded that, three kinds of Ferroresonance
with chaotic mode is presented with different characteristics.
Phase plan diagram (V-Φ) shows well-balanced circles in
normal state whereas; the circles are misshaped according to
type of Ferroresonance. Time-division can be set equal to the
period of power frequency. The plot shows irregular circles,
which are not repeated exactly in each time division. These
characteristics are the evidence of existing Ferroresonance
with chaotic mode. Fig. 6 shows Ferroresonance detection
tools.