March 14, 2012, 10:12 AM —
For a few years now, there’s been a debate over which power distribution architectures – DC or AC – are the most efficient for data centers. I know I don’t have to tell you, but for the record DC is direct current, which is a type of electrical current that travels through a circuit in only one direction. AC is alternating current (the most commonly used), which is an electrical current that frequently reverses direction electricity is measured according to its cycles, with one complete cycle being counted each time a given current travels in one direction and then doubles back on itself.
I recently talked with Kevin Brown, VP of Schneider Electric’s IT Business, about DC vs. AC. The company conducted an internal study through its Data Center Science Center, which conducts various research. All of the studies findings are presented in a paper, called “A Quantitative Comparison of High Efficiency AC vs. DC Power Distribution for Data Centers.” You can see the paper here.
Brown recounted the findings of a study published in 2008 that reported a 28% efficiency improvement of 380 volt DC versus AC distribution. The trouble is, Brown says, that paper compared an outdated AC architecture against a prototype DC architecture. “The reality is, this and a lot of other studies don’t do a true comparison,” Brown says, adding that the studies – while widely picked up by the media – generally provided too simplistic of a view.
The latest study by Schneider Electric compares the most efficient DC and AC power distribution methods, and in the end, find that both have practically the same efficiency.