When severe thunderstorms struck the Austin, Texas area in January, power outages lasting almost 15 sec threatened to crash computers serving a data center for Internet service providers and mission-critical applications for several Fortune 500 organizations.

However, a new flywheel-driven standby power supply at the Smart Technologies' data center kept millions of Internet subscribers in the dark about any power disruption, while applications for clients like Ziff-Davis, Minolta, Compaq, and Apple kept running as homeowners in the area fumbled to reset clocks on thousands of VCRs and microwave ovens.

Smart Technologies relies on its extensive data center and network of Internet servers to deliver enterprise management services. More than 200 computer servers and associated routers, switches, and modem pools occupy the Austin facility. Its power supply has two noteworthy characteristics. First, thunderstorms frequently cause power outages and surges in the area. Second, line voltage often varies outside the nominal 510V allowed by the utility.

When designing the new expanded data center, power quality was crucial. Reliability, redundancy, space limitations, and cost-effectiveness topped the list of critical considerations when designing the system and selecting components.

"We absolutely require a clean, reliable power supply under short- and long-duration outages," said Todd Enright, Smart's Information Technology Director.

Offering independent power supplies and backup for each server was complex, costly, and cumbersome. To provide better service at a lower cost, Smart selected a 160kVA UPS and coupled it with a unique flywheel-type of ride-through provider. Also included is a diesel engine-generator set and a minimum battery string.

The flywheel resides in a cabinet containing the spinning steel flywheel, which rides in a vacuum chamber on hybrid mechanical and magnetic bearings. Its kinetic energy provides continuous DC power for up to several minutes, depending on load characteristics when power falters.

The flywheel is rated for 200kVA, and the UPS is among the most cost-effective available. Reduced battery backup costs enhance the flywheel's return-on-investment. Fewer batteries are required, and fewer charging and discharging cycles extend their life. What's more, the space saved allows more floor space for equipment. The entire UPS and energy system occupies a 40-sq-ft area.

Installed after the new data center and UPS, batteries, and gen-set were operational, the flywheel has paid off. Only a matter of days after installation, thunderstorms raged through the area again. This time, the flywheel dramatically reduced the number of gen-set cycles. It sustained power throughout the entire period, triggering neither the gen-set nor the battery backup. In less than 100 sec, the flywheel returned to standby mode.