upsPhaseOutputMinPercentPower 1.3.6.1.4.1.318.1.1.1.9.3.3.1.18

The maximum percentage of the UPS power capacity in Watts measured at redundancy @ (n + x) presently being used on this output phase since the last reset (upsPhaseResetMaxMinValues), or -1 if it's unsupported by this UPS. Sampled every 30 seconds.