Nortel Networks NN44200-300 About the power distribution unit, DC power distribution rationale

40Chapter 4 Power supply installation

the same service panel as CallPilot and the switch, whether or not the equipment is AC- or DC-powered.

-48 V DC power distribution rationale

•Minimum installation is one power distribution unit (PDU) with four 48 V DC branch circuits fused at 20 amperes.

•The customer must be able to shut off any branch to ensure every unit at the site continues 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 V AC inverter).

•The secondary rack supports four servers and follows a similar scheme.

About the power distribution unit

Introduction

A PDU is installed in a rack that has DC-powered servers. Power from the DC supply source enters the PDU and can then be distributed to one or more servers. A single PDU can supply DC power to four DC power supply modules. A server can have either one or two power supply modules installed. You can determine the number of PDUs to install in a rack by counting the number of power supply modules in each rack.

PDU power and grounding

To ensure a complete power and grounding installation:

•In rackmount DC-powered server installations, ensure the PDU (Power Distribution Unit for DC applications) is installed on the same rack as the CallPilot server. This is required since the main ground wire for the PDU is not insulated from the metal enclosure.

Multiple PDUs

A server operates on a single power supply module. Its total capacity is two installed power supply modules. The second power supply module is the redundant power supply module.

Nortel CallPilot

1002rp Server Hardware Installation

NN44200-300 01.01 Standard

5.0 23 February 2007

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