39
l Based on the CBEMA curve, it is possible to construct a power acceptability curve for different voltages, selecting the voltage standard such that the resulting ‘CBEMA curve’ passes through the plotted event.  The value of standard voltage is Vp, compared to the CBEMA standard 0.87 per unit, and the ratio is the voltage sag index, Ipa.
Proposed voltage sag index based on the CBEMA curve