Compaq ProLiant BL e-Class System Overview and Planning

Compaq ProLiant BL e-Class System Overview and Planning 27
Redundant PDU Low-Line Example
This example presents a low-line configuration for PDU redundancy supporting one to two
enclosures. Figure 15 is valid for low-line PDUs with inputs rated >20 A. It does not support
three enclosures at low-line voltage because the total current load of 3 * 10 A = 25 exceeds the
input rating of 24 A.
Note: You cannot connect both enclosures to a single 15A output breaker because the total
current load of 2 * 10A exceeds the output rating of 12A (after 20% UL derating factor).
Figure 15. Low-line redundant PDU configuration supporting one to two enclosures
Determining Type and Number of PDUs: Non-Redundant PDU
Configuration
Use this procedure if using a non-redundant PDU configuration in which both power supplies are
connected to the same PDU. This ensures the enclosure’s built-in 1 + 1 power supply redundancy
works as intended, but does not provide PDU redundancy nor AC source redundancy.
The input current rating for a fully configured ProLiant BL e-Class server blade enclosure is 5 A
(200 to 240 VAC) or 10 A (100 to 120 VAC). This is the total current drawn by both enclosure
power supplies. To determine the number of server blade enclosures supported by a PDU, the
more restrictive of the following two rules must be observed.
The total number of Amps drawn from the PDU should not exceed the input rating of the PDU.
The number of Amps drawn from any branch of the PDU should not exceed that branch’s output
breaker limit.
IMPORTANT: Violation of either restriction could result in a “domino effect” that may disrupt
power to the enclosure, multiple enclosures, or the entire rack.