Nortel Networks CALLPILOT 555-7101-217 - Manual (Page 47)

May 2003 Power supply installation
Part 2: 1001rp Server Hardware Installation 47
-48VDC power distribution rationale
„ Minimum installation is one Power Distribution Unit (PDU) with four
48VDC branch circuits fused at 20 amperes.
„ The customer must be able to shut off any branch, and every unit at the
site will continue to function properly.
„ DC-powered configuration fits into this scheme as follows:
„ Each PDU receives four branch circuits.
„ Each server receives a feed from each PDU and a different branch
circuit.
„ In this fashion, with dual hot-swappable power supplies, there is no
single point of failure in the power system. For example, you can remove
any power supply, including a PDU, and everything continues to work.
„ This is applicable to either North American or European installation sites
(with a 230 VAC Inverter).
„ The secondary rack supports four servers and follows a similar scheme.