HP DL360 Power basics for IT professionals - Page 18

below shows three-phase and single-phase power delivery for some common circuit sizes in North America. Table 3 shows similar information for other countries. Please see the section entitled, "Panel distribution," for an example of the greater efficiency of threephase power. Also see the section entitled, "Wiring Methods," for more information about power calculations in North America and in Europe, the Middle East, and Africa (EMEA). Table 2. North American three-phase and single-phase delivery for common circuit sizes Circuit size De-rated value Single-phase power delivered Three-phase power delivered 30A 24A 4992 8640 50A 40A 8320 14400 60A 48A 9984 17280 80A 64A 13312 23040 100A 80A 16640 28800 Table 3. European, Middle Eastern, and African three-phase and single-phase delivery for common circuit sizes Circuit size Single phase power delivered Three-phase power delivered 16A 3680 11040 32A 7360 22080 63A 14490 43470 125A 28750 86250 Panel distribution The distribution panel is the central source of power distributed within the building. Power distribution panels are provided to connect single-phase and three-phase loads. The circuit breakers are located to divide the electrical loads equally between the phases to balance the electrical load on all three phases of the power panel. The number of poles or circuit breakers in the power panel determines how power is distributed. A pole is one line or one contact in the power plug that is live and carries power. A single-phase 120V circuit uses a single-pole circuit breaker; a single-phase 208V circuit uses a two-pole circuit breaker; and a three-phase 208V/120V circuit uses a three-pole circuit breaker. A standard power distribution panel for a data center provides approximately 150 kVA with 84 poles. A 208-V distribution requires two poles, which would require 42 two-pole positions out of the distribution panel. Power appears plentiful; however, in certain configurations distribution limitations leave power in the panel. For example, a rack full of 21 ProLiant DL380 G2 servers requires 8.6 kVA to operate. A 24A PDU at 208 V is limited to about 5 kVA. Consequently, the load requires at least two 24A PDUs. Redundancy 18