Practical Applications of Uninterruptible Power Supplies

A 2001 study by the Electric Power Research Institute found that electric power problems annually cost U.S. industry between $119 and $188 billion in estimated lost data, material and productivity. According to industry sources, businesses spend billions annually on power quality and reliability products in an attempt to reduce such losses.

Active Power's CleanSource® Flywheel Technology now offers a superior solution to this market and is typically employed to support one or more of the following practical applications for clients with high power reliability needs:

• Continuous power
• Power quality improvement
• Battery isolation and redundancy

Conventional critical power systems have been constructed from an array of devices, including batteries for short-term power disturbances, engine generators (commonly referred to as "gensets") for longer-term outages, and control electronics to bridge the two.

A short-term (seconds to minutes) energy storage device with control electronics is referred to as an uninterruptible power supply (UPS) system. A UPS system coupled with a genset to protect against longer-term outages (minutes to hours or days) is referred to as a continuous power system (CPS).

The lead-acid batteries that provide ride-through, or temporary power, power for the UPS system and CPS are commonly viewed as the most unreliable and most costly element of conventional power quality and reliability solutions. For applications that need relatively high power delivery over a relatively short period of time, the CleanSource system provides a superior alternative to existing battery-based energy storage solutions.

Continuous Power

In many circumstances, the end user of critical power has a strong desire to eliminate the requirement for electrochemical batteries due to environmental restrictions, maintenance concerns and/or limited space. If the critical power configuration includes a standby engine/generator for long-term protection, a CleanSource flywheel energy storage system is well suited for providing power until the start and synchronization of the genset.

Power Quality Improvement

Due to the fact that the vast majority of power quality events have a duration of only a few seconds, some power users have the opportunity to improve the quality of their power in all but long-term outage situations with minimal cost and space outlays. Batch or process manufacturing sites with a history of short-term power glitches or sags (which have remained unprotected due to the high costs or space requirements of traditional energy storage) are ideal applications for high-power flywheel systems.

Battery Isolation and Redundancy

One of the primary determinants of electrochemical battery life is the number of times the cell is discharged, the battery life being inversely proportional to the number of discharge events. A flywheel DC source is an effective means of protecting a chemical battery string with a small and durable package, thereby extending battery life significantly. The flywheel not only easily handles the vast majority of power quality events, but acts as a redundant DC power source in times of chemical battery maintenance or recharge.