UPS: Standby Systems Ideal for Small Applications

By Greg Livengood  
OTHER PARTS OF THIS ARTICLEPt. 1: This PagePt. 2: Line-Interactive UPS Offer Higher ReliabilityPt. 3: True Online UPS Offer Higher Power Quality, Compact SizePt. 4: Standby Online Hybrid UPS Improve Energy EfficiencyPt. 5: Flywheel UPS Require Less MaintenancePt. 6: Maintenance Requirements for Uninterruptible Power SuppliesPt. 7: PRODUCT FOCUS: Uninterruptible Power Supplies

In today's world of high speed and high expectations, critical facility systems or sensitive equipment downtime is not acceptable. Uninterruptible power supplies (UPS) can be essential components of standby power-distribution systems to protect equipment from events such as power interruptions, voltage variations, frequency variations, and transient disturbances.

A UPS is a stored energy system that provides ride-through power to critical equipment between the loss of normal — utility — power and the facility standby generators coming online, as well as during an orderly shutdown of the equipment.

Starting a generator and transferring power to a standby source often can take 10 seconds or more. According to the Electric Power Research Institute (EPRI), 98 percent of power outages last less than 10 seconds. Additionally, most electronic equipment will not tolerate more than a few cycles of power disruption before they shut down.

Standby Systems

A standby UPS, also called an offline UPS, is the most common small unit facilities use in personal computer applications. Under normal conditions, the standby UPS draws alternating current (AC) from utility power and switches to battery power within a few milliseconds after detecting a power failure. A standby UPS also provides noise filtration and surge suppression for improved power quality.

Among their benefits, the typical size ranges from 100 volt amps (VA) to 1 kilovolt amps (kVA). These units offer high energy efficiency, they are physically small, and they are relatively low-cost.

On the downside, they are not suitable for larger applications.

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  posted on 3/8/2010   Article Use Policy

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