c

F1 = 1.1 - 1.2 pu, duration > 1 min

Under voltage

F1 = 0.8 - 0.9 pu, duration > 1 min

Voltage interruption

F1 < 0.1 pu, duration: 10 ms - 3 s instantaneous interruption; 3 - 60 s temporary interruption; >60 s power off

Voltage sag

F1 = 0.1 - 0.9 pu, duration 10 ms - 1 min

Voltage swell

F1 = 1.1 - 1.8 pu, duration 10 ms - 1 min

Fluctuation and flicker

F1 is voltage fluctuation in 0.9 - 1.1 pu randomly