Inside a Rackspace data center. (Photo: Rackspace)

Inside a Rackspace data center. (Photo: Rackspace)

Enabling Alternating Phase Power Distribution at the Data Center Rack Layer

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The modern data center is a complex engine processing the world’s most complex workloads. Industry and user trends are indicating that reliance on data center resources will only continue to grow. This means that requirements around efficiency and rack-level density will grow as well.

Through all of this, data center operators are continuously tasked with running a more efficiently controlled data center platform. But how can you accomplish this with so many new connections and high-resource demands? How can you optimize the delivery of power to your most critical applications?

The demand for more power in the computer cabinet has led many data centers to upgrade to three phase power distribution. Proper three phase power distribution has traditionally meant dividing power into multiple branches within the rack PDU (Power Distribution Unit).

In this whitepaper from Server Technology we explore the advantages of a new, less common approach to PDU design by means of alternating each phase on a per-receptacle basis instead of a per branch basis.

Here’s something to think about: The principles of three phase power are not always well understood by the installer, whose only task is to power up the equipment being installed in the computer rack. Load balancing (matching current draw on each phase) is critical in these applications for multiple reasons:

  • If the three phases are not balanced, heat is generated resulting in higher cooling costs
  • Unbalanced loads lead to inefficiency and higher power bills
  • High loads on a single phase means greater chance of tripping either a PDU or upstream breaker, and losing power at the rack

Good practice in the data center is to install rack mounted equipment so that the current draw is similar on each branch. This is relatively easy if the rack is filled with only one type of device. Unfortunately this is often not the case. Mixed devices such as switches, storage devices, blade servers and different brands and types of 1U/2U/3U servers can create a crazy mesh of power cables in the back of the rack.

This can potentially inhibit airflow and add to the heat problems mentioned above.

So what can you do to improve power delivery? A solution to these issues is to use an alternating phase PDU. These specially designed PDUs alternate the phased power on a per-outlet basis instead of a per-branch basis.

Three phase power distribution at the rack level traditionally meant that power was divided into separate branches. Load balancing and cabling of these older PDU designs can be difficult.

Download his whitepaper today to see how power distribution units are implementing alternating phased power on a per-receptacle basis. You’ll also quickly see how this provides tangible benefits in the form of simplified cabling, better airflow, better load balancing and greater efficiencies – which ultimately will lower the operational expenses of the data center.

About the Author

Bill Kleyman is a veteran, enthusiastic technologist with experience in data center design, management and deployment. His architecture work includes virtualization and cloud deployments as well as business network design and implementation. Currently, Bill works as the National Director of Strategy and Innovation at MTM Technologies, a Stamford, CT based consulting firm.

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