Active Power launches flywheel with 60 second runtime

The company increased the speed of the rotor while keeping the same TCO

American backup power specialist Active Power has launched a flywheel that can keep the IT equipment running for as long as 60 seconds in the event of an outage, giving plenty of time to switch to an alternate power source.

The CleanSource 275XT UPS increases runtime by up to 78 percent over the current generation CleanSource 300 UPS, and the company calls it the longest runtime battery-free solution in the industry.

To achieve this, Active Power increased the speed of the rotor from 7,700 RPM to 10,000 RPM while keeping the footprint and even the price in line with previous CleanSource models.

“For us, there are really two ways to increase runtime on our flywheels: you either make it bigger or you spin it faster,” Anderson Hungria, senior product manager for UPS at Active Power, told DatacenterDynamics.

“We’ve made it bigger before, with our CSHD product, the 750kVA we’ve launched a few years ago. In this case, we’re spinning the wheel faster. And it’s the same 300 wheel that we developed about 13-14 years ago, and the main goal was to increase runtime but keep everything else the same.”

According to Active Power, today’s flywheels present a viable alternative to lead-acid battery banks typically employed in data centers, with up to 40 percent lower total cost of ownership, lower probability of failure and much lower carbon emissions.

Unlike batteries, flywheels don’t require dedicated cooling and don’t need to be replaced every few years.

CleanSource 275XT is a three-phase UPS supporting voltages from 380V to 480V, and rated at up to 275 kVA. Up to eight units can be paralleled for increased capacity and/en-US/or redundancy.

According to Active Power, 275XT can run for up to a minute at typical industry loads, which average about 40-50 percent. It would last 25 seconds at full load.

The amount of energy stored in a flywheel is proportional to the square of its rotational speed, so by increasing speed, the company achieved a considerable increase in runtime.

Hungria told DCD that Active Power had to tweak the cooling system, since a faster rotor generates more heat, replace some of the internal electronics of the modules, improve the ball bearings and rewrite the firmware in order to make 275XT a reality.

He admitted that not everyone needs a minute of runtime for their infrastructure: “Generators nowadays are up and running in 10 seconds or less, but there’s always a margin of error. It could be delays in the ATS, delays in the generator itself. We have a lot of customers who use parallel generators or sequential starts, where it will take about 8 seconds or so for each generator to start and they could be looking at 20, 30 or 40 seconds.

“Some end-users don’t even have generators today, and they are just switching over to a backup system. They need about a minute, a minute and a half of runtime while their operation is ongoing, and then they can essentially shut down their facility if they prefer it.”

CleanSource 275XT will begin shipping worldwide in the fourth quarter of 2016. Additional configurations and options will be available in the first half of 2017.

About Active Power

Active Power(NASDAQ: ACPW) designs and manufactures flywheel uninterruptible power supply (UPS) systems, modular infrastructure solutions (MIS), and energy storage products for mission critical applications worldwide from its headquarters and manufacturing plant in Austin, Texas. The company was founded in 1996 and became public in 2001.

Customers are served via Austin and three regional operations centers located in the United Kingdom, Germany and China, that support the deployment of systems in more than 50 countries. For more information, visit

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