Rack Powering Options for High Density in 230 V AC Countries

Overview

The paper is the IEC-market counterpart of the North American WP 29 and deals with rack power in 230/400 V networks. It considers 16 A and 32 A single-phase and three-phase whips, IEC 60309 connectors and C13/C19 outlets together. The goal is to set a sensible default feed for every rack and add dedicated whips only for unusual loads, rather than engineering each rack individually. That standardisation helps both installation and day-to-day operation of the room.

Its method is to tabulate the whip options and compare the power each can deliver to a rack along with an approximate unit cost. A single 230 V 16 A circuit carries 3.7 kW, and one to four circuits give 3.7, 7.4, 11 and 14.7 kW. The whip options span roughly 2.3 to 44 kW per rack. A 32 A three-phase whip delivers about 22.1 kW, while a 16 A three-phase whip delivers about 11 kW.

Breaker coordination is a key topic. To avoid the mismatch between a 16 A branch circuit and a 25 A feeder, the paper advises preferring 32 A three-phase whips over 25 A ones. It also points out that European 16 A breakers are typically 100%-rated, so the 80% derating familiar from North American practice is not applied in the same way.

On loading, the paper quotes expected rack densities by workload type: 9-22 kW for business workloads and 23-55 kW for scientific ones. According to the survey it cites, 6-10 kW per rack occurs about 48% of the time. The recommended default is a three-phase provision for every rack, with dedicated whips for unusual loads. Cost figures are indicative for 2 kW per rack and range from $270 to $645 per kW depending on whip type.

Key points

1. A 230 V 16 A branch circuit carries 3.7 kW; one to four circuits give 3.7 / 7.4 / 11 / 14.7 kW.
2. Whip options deliver about 2.3-44 kW per rack; a 32 A three-phase whip is about 22.1 kW and a 16 A three-phase whip about 11 kW.
3. Indicative cost at 2 kW per rack is $270-$645 per kW depending on whip type.
4. Prefer 32 A three-phase whips over 25 A to avoid 16 A branch / 25 A feeder coordination problems.
5. Expected rack density: business workloads 9-22 kW, scientific workloads 23-55 kW.
6. In the cited survey, 6-10 kW per rack occurs about 48% of the time.
7. European 16 A breakers are typically 100%-rated, unlike the 80% derating in NEC practice.
8. Default to a three-phase provision per rack, with dedicated whips for unusual loads.

Using it in design

• When the project region is IEC, start rack power from 230/400 V, 16 A or 32 A three-phase IEC 60309 whips.
• Compute rack kW without the NEC 80% factor, but keep a configurable continuous-load factor field.
• Offer density presets: business workload 9-22 kW, HPC/scientific 23-55 kW.
• Check coordination between branch and feeder breakers and recommend 32 A rather than 25 A three-phase whips.

Who should read it

Electrical designers and operations engineers planning rack power distribution on IEC networks.

Related standards

• IEC 60364
• IEC 60309
• IEC 60320
• EN 50600-2-2

Publication details

Authors

Paul Lin

Publisher

Schneider Electric

Year

2021

Document number

WP 28

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