Data Center Trend: Distributed Power in the White Space

Overview

The paper lists the benefits: incremental scaling, fewer points of failure, lower capex, right-sized efficiency and 480 V distribution without neutral. A 480 V UPS input and output needs no neutral (three wires instead of four) and thinner cables than 208 V, with a PDU next to the UPS stepping down to 208/120 V. Adding 100 kW to an existing modular UPS instead of buying a new one can save up to $35,000 upfront plus about $700 per year in footprint (at $150 per sq ft per year).

Distributed designs often avoid centralised downstream static switches, so a fault affects only a small portion of servers.

A white-space UPS needs modular vertical scaling, high efficiency at partial load, airflow options matching hot/cold aisle layouts, line-and-match cabinets, top/bottom cable entry, front access and integration with management software. White-space UPS models are quoted at 97% in double conversion and up to 99.1% in advanced modes, and UPSs are typically loaded below 50%.

On airflow, units should offer front-to-top (wall/row) and front-to-back (hot/cold aisle) airflow plus an optional chimney that leaves room for busway and trays.

Key points

1. A 480 V UPS input/output needs no neutral (three wires) and thinner cables than 208 V; a PDU next to the UPS steps down to 208/120 V.
2. Adding 100 kW to an existing modular UPS can save up to $35,000 upfront plus about $700 per year in footprint ($150 per sq ft per year).
3. White-space UPS models are quoted at 97% in double conversion and up to 99.1% in advanced modes; UPSs are typically loaded below 50%.
4. White-space UPSs should offer front-to-top and front-to-back airflow plus an optional chimney leaving room for busway and trays.
5. Distributed designs often avoid centralised downstream static switches, so a fault affects only a small portion of servers.

Using it in design

• Allow UPS placement in the white space with an airflow-pattern attribute (front-to-back, front-to-top) and count its heat release in the hall cooling load.
• Check UPS airflow direction against aisle-containment orientation and require front-service clearance.
• Offer a distributed (per-row or per-cage) UPS topology template.
• Compute the blast radius per UPS.

Who should read it

Designers choosing UPS placement in cloud and colocation halls, and the decision makers funding them.

Related standards

• IEC 62040-3
• ASHRAE TC 9.9

Publication details

Authors

Jason Anderson

Publisher

Eaton

Year

2013

Document number

WP153006EN

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