Simplify Power Distribution While Improving Reliability: Go Modular

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You’ve likely read lots of posts on this site about the benefits of modular, containerized data centers, including this popular  post on the topic by Neil Rasmussen.  I would like to take this concept further by offering a deeper dive into one area where a modular approach can deliver big benefits: power distribution.
If your data center is anything like most, the power distribution architecture you’re using to get power to your IT equipment was developed some 40 years ago. With the dramatic changes in data centers over the last few years, especially in terms of the density of IT equipment driven by virtualization and cloud computing, it could be time to take a fresh look.
Newer power distribution systems allow IT racks to be installed or changed without any new wiring. They use overhead distribution to reduce air flow problems, support rack densities up to 30 kW with a single flexible power feed, improve electrical efficiency, have a reduced footprint and a standard capacity management system.

In a recent revision to a Schneider Electric whitepaper, we compared five types of power distribution systems, including two modular systems:
– Overhead/under floor modular distribution
– Floor-mount modular distribution
The overhead/under floor system uses plug-in units powered by busway overhead or under the floor to feed IT enclosures. The power bus is generally installed over IT equipment rows. This approach addresses many limitations with traditional distribution, such as making changes easier and removing under-floor cabling. In the busway system, the IT enclosures directly connect into the busway via plug-in units with breaker boxes.
Among the advantages of this type of system is it takes up no room on the IT room floor, allows improved cable management and tracing, and reduces the inventory of cables you’ll need. They are also more reliable because it’s all pre-assembled, so there’s no need for cutting wires and terminating branch circuits in the field. Moves, adds and changes are also simpler because cables aren’t stacked on top of each other.
The floor-mount modular power distribution system uses branch circuit cables, distributed overhead in cable troughs to the IT enclosures. Instead of traditional circuit breaker panels with bolted wire terminations, modular PDUs have a backplane into which you install pre-terminated circuit breaker modules – thus eliminating on-site termination of wires. A new row of 24 IT enclosures, along with all of the associated branch circuit wiring and rack outlet strips, can be installed in an hour, with no wire cutting or terminations required.
This type of power distribution is well suited to projects involving the upgrade of an existing data center, to address additional capacity or installation of a high-density zone, because installation is less disruptive that with a traditional PDU.
It’s also a highly reliable system since the prefabricated backplane and branch circuit modules are well integrated. The systems also have plug and play intelligence for better capacity and change management as load requirements change and are easier to scale than traditional systems. And they can accommodate unusual room constraints since PDUs can be rolled into any location on the IT floor.
In general, these modular approaches to power distribution have a higher first cost per watt than traditional distribution. However, from a lifetime cost perspective, they have lower TCO because of the ability to implement changes faster, avoid stranded capacity (over sizing) with better capacity management, improve efficiency, and reduce maintenance expense.
For more details on how these modular architectures stack up to more traditional approaches, check out whitepaper number 129, “Comparing Data Center Power Distribution Architectures.” 


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