1.1 Voltage Sag
A Voltage Sag as defined by IEEE Standard 1159-1995, IEEE Recommended Practice
for Monitoring Electric Power Quality, is a decrease in RMS voltage at the power
frequency for durations from 0.5 cycles to 1 minute, reported as the remaining voltage.
The measurement of a Voltage Sag is stated as a percentage of the nominal voltage, it
is a measurement of the remaining voltage and is stated as a sag TO a percentage
value. Thus a Voltage Sag to 60% is equivalent to 60% of nominal voltage, or 288
Volts for a nominal 480 Volt system.