Which UPS is Right For the Job?
October 13th, 2009 By: Kevin Normandeau
Traditionally, data center managers and facilities managers could choose from three UPS topologies: standby, line-interactive and double-conversion—offering widely varying levels of efficiency, performance and protection. The latest generation of double-conversion UPSs offers unique multi-mode capabilities. The UPS operates in a very high-efficiency mode unless power conditions warrant a switch to the higher protective level typical of double-conversion mode.
This Eaton white paper describes how various UPS topologies work and looks at the impact of operating mode on five key factors of UPS performance:
- Maintaining voltage within tolerances
- Transferring among modes without locking up IT equipment
- Transitioning gracefully to and from generator power
- Reliability and availability
- Energy efficiency
Data center managers now have viable and remarkably cost-effective new choices with highefficiency, double-conversion, multi-mode UPSs that combine the best of single- and double-conversion topologies: exceptional efficiency plus the high protective level of double-conversion operation.
With best practices and the right choices in equipment, data center managers can reduce energy consumption by nearly 50 percent. That means that almost three-quarters of the power utility bill will fuel actual IT processing, compared to less than 50 percent of the power supplied to a normal data center today. To learn more download this white paper from Eaton.
JeffPosted October 13th, 2009
“With best practices and the right choices in equipment, data center managers can reduce energy consumption by nearly 50 percent. That means that almost three-quarters of the power utility bill will fuel actual IT processing, compared to less than 50 percent of the power supplied to a normal data center today.”
The paper makes quite a leap of logic. It discusses only UPS efficiency, and the prime example is switching from an 85% efficient unit to a 96% efficient one, which can be a dramatic savings but it’s nowhere close to an overall 50% gain in support equipment efficiency unless you run a data center that doesn’t spend ANY energy on cooling. For that to happen under more normal circumstances, you would need to switch from a 66% efficient UPS to a 100% efficient UPS. For example: a 1MW utility load with a compute load of 500KW, UPS loss of 250 KW, and AC load 250KW. To go from 50% overall efficiency to 75% overall efficiency you would need to erase ALL the UPS loss, and then you need to spend 250KW more on compute load without your AC load going up at all (i.e. to switch from 500/250/250 to 750/0/250). That seems like a bit of a stretch.
ErniePosted October 15th, 2009
I have to agree with Jeff, the UPS efficiency is the smallest part of the equation. Hot and cold isle arrangement and energy efficient cooling for the dense servers that are being utilized. These two elements are the corner stone’s to utility bill reduction.
The first step to efficiency is to have a cooling and power assessment to get a base line reading on the data center. Use the assessment to look for areas of improvement. Implement the changes noted and perform the assessment again. Numerous facilities have installed utility monitoring devices incorporated with the building management system to determine efficiency on a daily basis.
Gary Anderson, Marketing Manager for Applied Systems, Liebert Products and Services, Emerson Network PowerPosted October 15th, 2009
Emerson Network Power’s Energy Logic roadmap (http://tinyurl.com/7dhks3) presents a modeled scenario for enhancing data center energy efficiency and found that the UPS represents just 5 percent of the total power consumed in the data center today. While enhancing UPS efficiency is important, a 2 percent improvement in UPS efficiency could not account for a 50 percent improvement in data center efficiency, even when the cascading effect of energy savings across systems is taken into account. There is also some risk associated with going to different topologies—you may be trading efficiency for availability. Data center managers should really look at the potential impacts of new technologies to ensure that they are improving efficiency without compromising on availability.