Today’s LiveWire Spotlight examines NERC’s new technical document addressing the effect that depressed transmission voltages will have on Unit Auxiliary Transformer (UAT) Loadability settings. The need arose from a potential gap identified during the development of PRC-025-1 that would lead to an inappropriate generator trip during an undervoltage condition.

For now, NERC is satisfied that the setting criteria recommended in SPCS’ Technical Reference on UAT Loadability During Depressed Voltages addresses the reliability need. This could change if an event occurs or new data indicates a gap exists.