Redundant Power Distribution - HP ProLiant DL140 - G2 Server Introduction Manual

Redundant power distribution

Redundant power systems require two power distribution circuits, one for each power bus. Redundant
operation requires configuring servers with redundant power supplies, each capable of supporting the
full load of a server, if necessary. For redundant operation, the PDU or PDUs for each bus should be
configured to handle less than half of their rated capacity for normal operation so that they can
handle the full load of the system if one bus fails. The example shown in Figure 6 is based on an HP
ProLiant server with a current draw of 1.9A operating with 208 VAC common to North America and
Japan. The PDU for each bus feed must handle the full rack load (in this case, 32A) if one bus fails. In
Figure 6, multi-segment 40A PDUs satisfy this requirement with adequate headroom.
Figure 6.
Redundant power distribution
16 A
208 VAC (see text below)
However, if the system in Figure 6 were operating in a 230 VAC environment, 32A PDUs could be
used. The current draw of the same ProLiant server operating 230 VAC will be 1.7A each, resulting
in a PDU current load of 13.6 A for normal operation and 27.3 A for all16 servers in redundant
operation.
NOTE
:
Depending on the server system employed, the actual load
on redundant buses during normal operation may not be
evenly divided.
PS A
40A
PDU
HP ProLiant
servers
1 thru 8
PS A
HP ProLiant
servers
9 thru 16
Bus A
Normal operation (see note below)
PS B
40A
PDU
32A
PS B
16 A
Bus B
208 VAC (see text below)
Redundant operation
(Bus A failure)
8