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Technical guideFree to read2015

Power Distribution as a System within the High-Density Data Center

Legrand · Server Technology, Inc.

Server Technology (now Legrand) argues that rack PDUs and their management software should be designed as one system with the rest of the power chain. With densities rising and modular builds leaving little margin, PDU selection becomes a metering and capacity decision.

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Overview

The paper observes that typical cabinets moved from 42U at 5 kW to 45U-52U at about 17 kW in newer facilities. Readers are told to prepare for upwards of 20 kW per rack and hot aisles of 60 C or more. Those two figures show the PDU is a thermal component as much as an electrical one.

The measurement section is built around PUE and DCeP. It argues that rack-level (Level 3) measurement is needed to understand the capacity actually used. PDU metering verified by UL to +/-1 % billing-grade accuracy against ANSI C12.1-2008 is the technical basis for using the data in customer billing too. The internal PDU monitoring architecture is also described.

The product range spans 120 V/20 A to 100 A three-phase 208 V and 63 A three-phase 415 V, plus 600 A -48 VDC distribution. Central power-management software is positioned to bring capacity planning together across mixed single- and three-phase installations. The text comes from a manufacturer and dates from 2015, so its density figures reflect facilities of that period.

Key points

  1. Typical cabinets moved from 42U/5 kW to 45U-52U/about 17 kW in newer facilities.
  2. Operators should prepare for upwards of 20 kW per rack and hot aisles of 60 C or more.
  3. Rack-level (Level 3) measurement is needed for PUE and DCeP.
  4. PDU metering is UL-verified to +/-1 % billing-grade accuracy against ANSI C12.1-2008.
  5. Range runs from 120 V/20 A to 100 A three-phase 208 V and 63 A three-phase 415 V, plus 600 A -48 VDC.

Using it in design

  • In the PDU catalogue keep fields for input (V, A, phases), metering accuracy class and operating temperature rating, using 60 C as the hot-aisle reference.
  • Add a rule requiring metered PDUs at every rack when the designer selects PUE Category 3 reporting.
  • In the capacity view, aggregate PDU readings by cabinet, row and phase.

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Who should read it

Designers and operations engineers planning rack power metering and PUE reporting.

Related standards

  • ANSI C12.1-2008
  • The Green Grid PUE
  • ASHRAE TC 9.9

Publication details

Authors
Server Technology, Inc.
Publisher
Legrand
Year
2015
Document number
STI-100-016
Document language
English
Source type
Manufacturer
Access
Free to read
Licence
Copyright retained; citation only — the publisher’s terms apply to the original document

Citation

Server Technology, Inc. (2015). Power Distribution as a System within the High-Density Data Center. Legrand. STI-100-016. https://cdn10.servertech.com/assets/documents/documents/62/original/WP_Power-Distribution-as-a-System_Rev_2-0.pdf?1452798581

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