What Is High Power?
High power consumption at a rack may take the form of a few devices, each of which consumes a lot of power, such as blade servers and blade chassis requiring 5kW or more per chassis, or many moderate power consumption devices, such as a 42U rack filled with 42 1U “pizza box” servers, each server requiring 200-300 watts. There are several ways of deploying power in these scenarios and an approach which works for a high-outlet-density situation may also work for a situation where a lot of power needs to be deployed to a few power hogs.
Some data center managers add power by running more circuits. But, in general, it does not make sense to run several whips (power cables) to devices with multiple power supplies such as blade servers. It is easier and more economical to run two high-power feeds, either by under-floor whips or an overhead system, to a pair of high-power rack PDUs. From the high-power rack PDUs, short cables can be run to the power supplies, making for a much cleaner, e.g., less under-floor air obstruction, and more manageable deployment. Economics also improve with savings in copper and component costs.
When considering power demand, it is important to determine and design for peak actual demand. Designing to IT equipment nameplate ratings is excessively high. Designing for average power consumption may not be sufficient for periods of peak demand.