The Difference in UPS Designs
There are three basic UPS designs: off-line, line-interactive and on-line. They provide three different levels of backup and power protection.*
Off-Line – The off-line UPS is the lowest cost and is capable of providing basic battery backup and limited surge protection only. In every case the unit is designed around low cost. Therefore, in battery mode it does not provide a true sinewave output and instead it has a very distorted quasi-sine and even square-wave outputs. When in utility power mode, the utility power is fed directly to the UPS output without any power conditioning.
Line-interactive – This type of UPS is very similar to the off-line, except it has an internal automatic tap switching transformer circuit (AVR) that attempts to maintain some output voltage regulation in gross steps. Depending on the cost of the line- interactive UPS, the battery mode output waveform could be quasi-sinewave or true sinewave in some cases. Again, when in utility power mode, the utility power is fed directly to the UPS output, without any power conditioning. A good quality line-interactive UPS will cost substantially more than an entry level line-interactive model. This type of UPS is best suited for non-critical workstation based applications.
On-line – This is the best grade UPS. When powered by the utility source it converts the AC to a regulated DC, thereby removing most unwanted utility power problems. It then regenerates new, clean true sinewave output power 100% of the time, whether operating in battery or utility mode. The on-line UPS acts like an electronic firewall between the utility power and connected equipment. It is the best choice for use in any medium to large business, industrial, scientific or IT application. The on-line UPS is the only truly generator compatible UPS since, unlike other UPS types, it eliminates generator frequency shifts and voltage sags. As the on-line UPS incorporates a continuous duty inverter, it supports the connection of extended runtime battery packs, allowing runtimes over several hours.
Conclusion – We are an engineering oriented company that for 25 years has been committed to producing highly reliable UPS solutions. In fact, Falcon’s products are used to protect military equipment and personnel in the Middle East. This type of UPS truly makes a difference, like the 911 call center being upgraded in Los Angeles!
*This is an excerpt from “True Cost of UPS and Batteries” tutorial on our website.