This reports what percentage of this phase's designed, non-redundant capacity is currently being consumed, where the denominator specifically excludes any modules configured as redundant spares, making this the more conservative, real utilization figure compared to tsiPhaseAvailablePowerRatioW's more generous all-modules-counted version. It is the number an admin should actually watch for capacity-planning alarms, since it reflects what the phase can sustain if it loses its redundant module to a failure, unlike the available-power ratio which assumes every module including spares stays healthy. An admin setting a capacity alert threshold would base it on this installed-power ratio crossing, say, 80%, since that reflects true risk to service if a redundant module were to fail at that moment.