UPSonNet recent survey indicates that most Line Interactive and Standby UPS systems are prone to drop load when powering new servers build to Energy Star requirements. To help specifying and selecting a proper APC system, UPSonNet introduces new Line Interactive and Standby UPS guide. APC was selected due to its dominant market position in the Line Interactive and Standby UPS field; same methodology can be used for other makes.
Miami, FL, July 29, 2010 — UPSonNet recent survey indicates that most Line Interactive and Standby UPS systems are prone to drop load when powering new servers build to Energy Star requirements. To help specifying and selecting a proper APC system, UPSonNet introduces new Line Interactive and Standby UPS guide. APC was selected due to its dominant market position in the Line Interactive and Standby UPS field; same methodology can be used for other makes.
To meet latest green oriented legislation, aimed to increase efficiency and decrease harmonic losses requires introducing Active Power Factor Correction (APFC) circuits in computer server power supplies. The new servers are designed to work properly from sinusoidal sources such as utility line, or most online UPS systems, but are prone to fail when powered from most Line Interactive or Standby UPS units.
Introduction of the new computer types has immense significance on selecting and specifying UPS systems, particularly related to the following two points:
Both UPS Watt and VA Ratings should be considered when sizing a UPS.
Conservatively, Total Server’s Power measured in VA (Volt –Ampere) units is considered the main figure to specify UPS size. Actual server’s power, measured in Watt units, was generally less than 70% of VA rating. Accordingly UPS Watt rating and the actual power which most UPS systems can supply is 70% lower than its VA rating.
New servers with APFC circuits, eliminate the parasitic harmonics resulting in almost equal Watt and VA ratings. Now, both UPS VA and Watt rating should be considered. Each has to be above the respectable total requirements of all computers which will be protected by the UPS. More on this is presented on UPSonNet article: Mind Watts when specifying a UPS.
Sinusoidal UPS Output Waveform should be Preferred.
Standby and Line Interactive UPS systems power the critical load from utility line, as long as it is within specified voltage window. Both systems are equipped with a standby inverter connected to UPS battery, which kicks in to support the critical load via the inverter from battery, whenever utility power fails or deviates beyond the voltage window boundary.
Unlike Online UPS systems, almost 100% of Standby and 70% of Line Interactive UPS systems, due to economic considerations, provide not a sine wave but a pulsed (called also modified or stepped ) Inverter waveform. These systems work fine with conservative servers; they do not generally comply with new server requirements.
New servers work correctly with the utility line power; however the exact behavior when the load is switched to Inverter operation with non sinusoidal waveform depends on the particular server’s power supply design. UPS output may drop, particularly at high loads, either due to computer power supply malfunction when connected to such UPS, or due to UPS shut down because of overload occurring when it switches from line to battery backup.
Most users are still unaware of the problem, still mainly discussed in users’ forums, whereas the amount of computers with APFC circuits is continuously growing due to computer manufacturers’ effort to comply with regulations.
Most Online UPS trading stores and UPS sellers are unable to assist buyers.
The problem of selection a sinusoidal UPS is further complicated because most UPS sellers have no idea about the output wave form of the UPS which they sell, and lack the knowledge to assist buyers. Additionally, the type of UPS waveform isn’t generally presented on trading websites, and not always mentioned in UPS brochures, sometimes not even declared in technical UPS specs.
UPSonNet guide bridges the information gap by presenting main specifications and features of single phase Line Interactive and standby UPS systems from 450VA up to 3kVA, including information about UPS power and waveform to guide users which UPS system to select in order to protect new computers and which systems to avoid.
For more information visit: APC Line Interactive and Standby UPS Products Guide.
UPSonNet founded in 2006 in USA (now operating also from Israel) is solutions and information source of interest to users, service providers and professionals involved in design, manufacturing, marketing and implementation of UPS and Power Protection systems. For more information visit: www.upsonnet.com.
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Contact:
Meir Portnoy
UPSonNet
Miami, FL
305-517-7886
[email protected]
http://www.upsonnet.com
