| stable state in which a credible event can cause loss of load, over-stressing of components, bus voltages and system frequency outside tolerances, cascade tripping and/or instability|
Figure 2 – Electric power system states
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
Figure 6 – Examples of electric power system states and corresponding system operation status
Note 1 to entry: When in the alert state, a further credible event can result in an unstable state.
Note 2 to entry: This entry was numbered 191-22-06 in IEC 60050-191:1990.