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One per BPCE for populations of one to three BPRs/BPCE and two per BPCE for four to
six BPRs/BPCE.
The front and rear views of the BPCA are shown in Figure 1-33.
BPCH
Figure 1-33 BPCA
The minimum configuration per BPCE is one x BPCH, one x BPD, one x BPR and one line
core. There are always two BPCAs above one another in the top of the cabinet.
BPRs are added uniformly to each BPCE depending on the power load in the rack.
A single fully configured BPCE provides 27 KW x 6 = 162 KW of Bulk Power, which equates
to aggregate system power cord power of approximately 170 KW. Up to this power level, bulk
power is in a 2N arrangement, where a single BPCE is removed entirely for maintenance
concurrently with the rack that remains fully operational. If the rack bulk power demand
exceeds 162 KW, the bulk power provides an N+1 configuration of up to 27 KW x 9 = 243 KW,
which equates to aggregate system power cord power of approximately 260 KW. N+1 Bulk
Power mode means one of the four power cords are disconnected and the cabinet continues
to operate normally. BPCE concurrent maintenance is not conducted in N+1 bulk power
mode, unless the rack bulk power load is reduced to less than 162 KW by invoking Power
Efficient Mode on the server nodes. This mode reduces the peak power demand at the
expense of reducing performance.
Cooling
The BPCA is nearly entirely water cooled. Each BPR and the BPD has two quick connects to
enable connection to the supply and return water cooling manifolds in the cabinet. All of the
components that dissipate any significant power in the BPR and BPD are heat sunk to a
water-cooled cold plate in these units.
To assure the ambient air temperature internal to the BP, BPCH, and BPD enclosures is kept
low, two hot pluggable blowers are installed in the rear of each BPCA in an N+1 speed
controlled arrangement. These blowers flush the units to keep the temperature internal at
approximately system inlet air temperature, which is 40 degrees-C maximum. A fan is
replaced concurrently.
Front View
Rear View
Chapter 1. Understanding the IBM Power Systems 775 Cluster
BPR
BPR
BPE
BPD
43
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