The generators can start up in three seconds. For the time between failure and startup, kinetic energy from flywheels spun up using mains power is used to keep the generator running. From mains failure the flywheel gives 16 seconds of power.
Using a flywheel removes the requirement of batteries for the time until generators start up, saving the data centre 300 square metres of floor space, Andrea said.
"People might say 'Holy hell' what if [the generator] doesn't start," he said, referring to the short 16 seconds of time the flywheel gives. However, the datacentre had two more generators than it needed, he said, and added that if generator genuinely wouldn't start, the ten minutes provided by the batteries datacentres normally have wouldn't be enough anyway.
When there was a brown out, or a time when less mains power was available than usual, energy from the flywheel could be used to make up the difference, Andrea said. If the brown out lasted longer than seven or eight seconds, it was treated like a black out, with generators springing into motion.
(Credit: Paul Riley)
Why put the generators on the 5th floor rather then the ground floor?