VFI is Voltage & Frequency Independent and VI is a Voltage Independent UPS. VI class UPS systems could save energy assuming that the utility power is of an acceptable quality from a frequency variation point of view..
150kW plus expected losses due to any potentially in-efficiency
If using standard perforated tiles then not to exceed more than 25% tiles should be perforated
8% THDv or less
Tier levels are defined by the Uptime Institute® whereas Rating levels are defined by ANSI/TIA-942. Tier levels only describe power and cooling requirements whereas Rating levels of ANSI/TIA-942 cover power, cooling, architectural and telecommunications.
No, Rated-4 of TIA-942 does not require two different power utility companies. The only requirement is two different substations which can be owned by a single power utility company.