alert state in which a credible event will result in instability, voltage collapse or cascade tripping ![](/iev/iev.nsf/FiguresShared/692-fig2-en/$file/692-fig2-en.png)
Figure 2 – Electric power system states ![](/iev/iev.nsf/FiguresShared/692-fig3-en/$file/692-fig3-en.png)
NOTE The arrows indicate the most important state transitions caused by credible events. Recovery transitions, in opposite directions, are effected by operator intervention. Figure 3 – Examples of transitions within electric power system states Note 1 to entry: This entry was numbered 191-22-07 in IEC 60050-191:1990.
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