This reports how many modules on this phase have actually failed, not delivering output due to a genuine fault, distinct from tsiPhaseNbModMO's deliberately-off modules, making this the count that should drive real fault alarms rather than routine maintenance notifications. It is the clearest single indicator of degraded redundancy on this phase: if this count meets or exceeds tsiPhaseRedundancy, the phase has already lost its designed protection margin and any further module failure would directly threaten service. An admin's highest-priority alert on this power system would trigger when this count on any phase reaches or exceeds that phase's configured redundancy value.