Edison vs Tesla: A rematch in the telecom data center

For over a century, since the invention of the telephone, the telephone network has relied on DC Power and has used DC battery reserve to provide “continuous dial tone”, even during commercial power outages. The debate between proponents of George Westinghouse's AC and Thomas Edison's DC commercial power distribution schemes has raged just about as long as the telephone has existed. The debate over the use of AC and DC Uninterruptible Power Supplies (UPS's) is more recent. Powering Telecommunications equipment has long been dominated by DC UPS's while Computer equipment has traditionally been backed up by AC UPS's. The metamorphosis of telecommunications networks into Information and Communications Technology (ICT) networks with their reliance upon digital technologies has blurred the distinction of these systems and the choice of UPS technology reflects this. Changing requirements and advances in battery chemistries, power system efficiencies and software controls are all affecting choice of power system architecture. This paper examines the changing requirements of ICT network equipment and their effect on the various AC and DC UPS architectures that are available to power them. Changing requirements have opened up opportunities for different power architectures utilizing new battery chemistries, while advances in power conversion equipment allow power systems to be placed in different locations, improving distribution efficiency. Continuous pressure for operational cost reduction is fueling the need for more efficient “end to end” systems, as well as reducing capital costs of equipment. Total Cost of Ownership (TCO) is now a key ingredient in the choice of power architecture alongside the questions of reliability, availability, reserve time, redundancy and scalability. The impact of all these key ingredients is examined. This paper examines these advances with a view to better understanding the trends in power architectures and implementation. This may also allow us a glimpse into the “crystal ball” of future developments and trends.