Uninterruptible Power Supplies: A Critical Power Play

Part 1: UPS: Standby Systems Ideal for Small Applications

Part 2: Line-Interactive UPS Offer Higher Reliability

Part 3: True Online UPS Offer Higher Power Quality, Compact Size

Part 4: Standby Online Hybrid UPS Improve Energy Efficiency

Part 5: Flywheel UPS Require Less Maintenance

Part 6: Maintenance Requirements for Uninterruptible Power Supplies

Part 7: PRODUCT FOCUS: Uninterruptible Power Supplies

Line-Interactive UPS Offer Higher Reliability

By Greg Livengood - February 2010

These UPS continually condition and regulate AC utility power to equipment via a power converter. Upon loss of utility power or when the utility power falls outside of the input range of the power converter, the UPS battery will support the loads via an inverter. The power converter filters the utility AC power, suppresses voltage spikes and regulates the voltage to provide the required power to equipment loads.

Typical applications include small businesses and departmental servers, and the size usually ranges from 0.5-6 kVA.

Among its advantages, the cost is relatively low, and it offers an energy efficiency of 96-98 percent. Line-interactive UPS also offer high reliability because they have fewer components.

Among its disadvantages is size. The units are larger than some other topologies, and they do not provide power-factor correction or frequency regulation. Also, in areas of extreme voltage distortion, line-interactive UPS require frequent battery use.