Specifications

fault-tolerant power
compliance in the rp8400
features of the ac power
system
20-amp circuits
The ac input to the rp8400 has been divided into four separate circuits. Each circuit can be fed by
any 50- to 60-Hz high line source through four line cords. (”High line” refers to 220–240 volt
operation.) A minimum of two power cords must be used to maintain normal operation of the
rp8400. A second set of two cords can be added to improve system availability by protecting, for
example, against power grid failures or accidentally tripped circuit breakers. This power is routed
from four individual 20-ampere circuit breakers via input line filters to six internal bulk power
supplies (BPSs). These four lines are labeled A0, B0, A1, and B1 at the line filter inputs on the
back panel of the rp8400.
Figure 14 shows the rp8400 power configuration. Note that each ac inlet feeds three rp8400
bulk power supplies and that two separate ac inlets feed each bulk supply. The design of the
individual BPSs and the configuration of the interconnect meet all the conditions listed above for
fault-tolerant power compliance.
figure 14. Power inputs and interconnects in the rp8400 are designed for fault-tolerant
power compliance.
The rp8400 ac power configuration has several salient features designed for the convenience of
the user. First, and most important, are the four 16-/20-ampere power cords used for 2N power.
At first glance, it may appear that using two higher-amperage cords would have been better.
HP considered this solution but rejected it because this would have required either two 30-ampere
3-phase cords or two 40-ampere single-phase cords. Research has shown the many customers
do not have three-phase power in their data centers, and some countries don’t allow 40-ampere
single-phase branch circuits. In short, using four lower-amperage cords is the only solution that
will fit all data centers.
For customers who prefer to use just two cords for 2N power, HP has designed a 60-ampere
rack-mounted power distribution unit (PDU). The PDU consolidates the rp8400 cords into a
configuration with a single cord per grid. For more information about the PDU, see page 23.
In the rp8400, the 20-ampere circuits provide:
• flexible, manageable, small-radius cables to and inside the cabinet containing
the rp8400 system
• economical cables, plugs, receptacles, and wiring that keep costs down
• easy system installation because of the general availability of 20-amp circuits
• manageable cabinet internal wiring, coupled with the ability to use just two single high-
amperage cables for mains power to the cabinet, via the addition of large-amperage cabinet-
housed PDUs.
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