This is the VA equivalent of tsiPhaseInstalledPowerInW, giving the phase's non-redundant installed capacity in apparent power rather than real power, the absolute-VA figure behind the percentage in tsiPhaseInstalledPowerRatioVA. When planning to add a load with a known power factor, comparing that load's VA demand against this figure rather than the watts figure gives a more conservative and physically accurate headroom check. An admin adding equipment specified in VA rather than watts on its nameplate would compare its rating directly against this object rather than converting it to watts first and risking a unit-conversion error.