With the proliferation of electronic loads such as computers, the incidence of power quality-related problems is growing. As a result, the uninterruptible power supply (UPS) market has grown significantly in the last few years. What follows is an overview of UPS functions and descriptions of common types of UPSs and backup power sources. UPS Functions The primary purpose of a UPS is to provide conditioned, continuous power to its load. Another UPS function that is of growing importance in today’s market is system integration, or the. | 16 Uninterruptible Power Supplies Laura Steffek Best Power John Hecklesmiller Best Power Dave Layden Best Power Brian Young Best Power UPS Functions Power Conditioning System Integration Static UPS Topologies Double-Conversion UPS Line-Interactive UPS Standby Power Supplies The Rotary UPS Alternate AC and DC Sources Batteries DC Generators Superconducting Magnetic Energy Storage AC Generators With the proliferation of electronic loads such as computers the incidence of power quality-related problems is growing. As a result the uninterruptible power supply UPS market has grown significantly in the last few years. What follows is an overview of UPS functions and descriptions of common types of UPSs and backup power sources. UPS Functions The primary purpose of a UPS is to provide conditioned continuous power to its load. Another UPS function that is of growing importance in today s market is system integration or the ability to communicate over a network to facilitate the monitoring and orderly shutdown of loads. Power Conditioning A UPS provides continuous regulated power to its load under all conditions of the utility power line. Unlike other types of power conditioning equipment a UPS provides power during outages. Typically a UPS will provide backup power for 10 or 15 min although longer times are possible with large battery strings or a DC generator. A UPS will also correct for high- and low-voltage events known as surges and sags. This regulation is provided either electronically or by a tapped transformer or a ferroresonant transformer. Normal mode or line-to-line transients are prevented from reaching the load. This is accomplished either with filter components or in a double conversion UPS by converting the AC to DC and then back to AC. There is quite some variation in the ability of UPS systems to protect the load from common mode or line-to-ground transients. Safety agency requirements preclude most forms of common mode transient .
