415V AC Power Distribution

The critical power system presents a modest opportunity to reduce energy consumption; however, particular care must be taken to ensure that reductions in energy consumption are not achieved at the cost of reduced equipment availability. Most data centers use a type of UPS called a double-conversion system. These systems convert incoming power to DC and then back to AC, which enables the UPS to generate a clean, consistent waveform for IT equipment and effectively isolates equipment from the power source. UPS systems that don't convert the incoming power can operate at higher efficiencies but may compromise equipment protection because they do not fully condition incoming power. A greater opportunity exists downstream from the UPS. In most data centers, the UPS provides power at 480V, which is then stepped down via a transformer, with accompanying losses, to 208V in the power distribution system. These stepdown losses can be eliminated by converting UPS output power to 415V. The 415V three-phase input provides 240V single-phase, line-to-neutral input directly to the server. This higher voltage not only eliminates stepdown losses but also enables an increase in server power supply efficiency. In the Energy Logic model, an incremental 2 percent reduction in facility energy use is achieved by using 415V AC power distribution.