rPDUOutletControlOutletPhase
1.3.6.1.4.1.318.1.1.12.3.3.1.1.3
The phase/s associated with this outlet.
For single phase devices, this object will always
return phase1(1).
For 3-phase devices, this object will return phase1 (1),
phase2 (2), or phase3 (3) for outlets tied to a single
phase. For outlets tied to two phases, this object will
return phase1-2 (4) for phases 1 and 2, phase2-3 (5) for
phases 2 and 3, and phase3-1 (6) for phases 3 and 1.