This reports how many modules in this AC group are actively delivering output normally, the group-level equivalent of tsiPhaseNbModOK but scoped to AC grouping rather than electrical phase. When a group's shared AC feed itself is healthy but individual modules within it are still failing for unrelated reasons, this figure isolates active-output count specifically within that group regardless of what phase those modules happen to be wired to. An admin troubleshooting reduced capacity on a phase would cross-reference this per-group count against the phase-level tsiPhaseNbModOK to see whether the shortfall is concentrated in one particular AC group.