DC Power in Data Centres

The discussions amongst Data Centre specialist about the relative benefits of AC and DC are by far the most heated. In my opinion these are mainly driven by the technology that the protagonists are most comfortable with. The 20th Century Data Centre guys are all into AC, it is what they have been working with since the 60’s and in the Data Centre business everyone is risk averse. The cost and impact of a failure are too painful to contemplate.

The 21st Century guys and the Telecommunications industry guys are much, much more comfortable with DC. They have been using it (in the case of Telecommunications) for decades and their numbers say that the technology is simpler, cheaper and more reliable.

Let’s look at it logically, you may remember from the Power article that 20th Century data centres do a lot of power conversions. Power comes in from the grid as AC and gets rectified to DC to charge batteries. The batteries then drive UPS equipment that generates AC that, in turn, powers the servers, network and storage equipment in our data centre. This equipment has power supply units that convert from AC back to the DC that the chips inside the equipment need to operate.

Why not do it the 21st Century way and bring the power is as AC, charge the batteries so that we can survive an outage and then run the equipment directly from DC? Pretty much every manufacturer has SKUs for DC powered equipment. For example much of Sun Microsystems SPARC range of servers is available in Telco Form utilising DC power sources.