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Run UPS at Capacity and Maximize Efficiency

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Is Your UPS System Running Efficiently and at Capacity?

UPS EfficiencyUPS efficiency is one of the most critical components of effective data center operations.  When a UPS system is not running efficiently, it can drain the life of your UPS battery more quickly than necessary or, worst of all, fail when it is needed most.  Regardless of which scenario you face, both outcomes are frustrating and expensive.  And, UPS batteries are not the only components of a UPS system that can fail or run inefficiently. There is also the UPS fan and capacitor, as well as other elements.  

If you try to simply guess or assume how efficiently your UPS system is running, you may quickly find out that your guess could be very inaccurate.  Even if your UPS system appears functional and efficient, there are ways to test and determine whether or not it is running efficiently and at capacity.  This is important to know because if your UPS system is not running efficiently, it could be costing you a lot more money to run than it should.

Proper UPS Sizing for Efficiency

One of the most common problems with UPS efficiency happens before the system is ever installed.  Many times, data center operators will opt for a UPS with a capacity far larger than their needs are currently or will be in the near future.  Or, conversely, they choose one that is slightly too small, hoping to save a little of up-front cost and run it at ‘capacity.’  But, in either of these scenarios, when the UPS is not sized correctly, it will never run as efficiently at capacity as it could.  You cannot base a UPS’s system efficiency at what it is rated at by the manufacturer because a UPS system is typically tested at 100% load, which is almost never the case in any real data center application.  Consider your unique and specific data center application before choosing the UPS system for your needs.

Another factor to consider when evaluating what the ideal size is for your UPS system and how to maximize efficiency is whether or not your UPS has an ‘eco-friendly’ mode.  Energy Star explains the advantages of using the eco-friendly mode on your UPS system to maximize efficiency, “Some UPS systems feature an “eco mode.”  This is a broad term used to describe any UPS mode of operation that improves the efficiency of the system.  However, the efficiency increase comes with a particular trade-off in performance or reliability, which varies by vendor.  In many UPS systems, eco mode is synonymous with “bypass mode,” in which the UPS system allows utility power to bypass the rectifier and inverter and directly feed the IT load.  In bypass mode, losses from the inverter/rectifier circuits are eliminated.  This can reduce data center energy costs by as much as two to eight percent.”

UPS Battery Life

Often, a data center manager or IT professional will look at the life expectancy of a UPS battery and assume it will last that long.  But, as anyone that has spent some time working with UPS batteries know, that is not the case.  While a UPS battery life expectancy may be 7 years, that estimation is based on testing in a controlled environment with optimal conditions.  The reality of functioning data centers is much different than that controlled testing environment.  In data centers that can be temperature fluctuations throughout the day that may be minor or extreme, there can be moisture, dust, poor maintenance, overloading, and many other factors that reduce the lifespan of a UPS battery more quickly than anticipated.  

Proper UPS Maintenance and Monitoring for Efficiency

One of the best ways to track UPS efficiency and prevent potential downtime from UPS failure is routine maintenance and monitoring.  If you are not monitoring your UPS efficiency on a routine basis, you will have no baseline to know when efficiency is declining.  UPS maintenance and monitoring should be a part of any data center infrastructure management strategy.  Do you really know how efficiently your UPS is running?  At what load capacity is it running? Energy Star explains why understanding load capacity is an incredibly important part of maximizing UPS efficiency, “New energy-efficient UPSs generally range from 92% to 95% efficient.  However, a UPS does not always operate as efficiently as its rating suggests. Instead, its efficiency follows a curve based on its “load factor” —how much of its power capacity is being used. If the UPS is operating at 100 percent capacity, it will run as efficiently as its rating implies. But if the UPS is operating at a lower capacity, as almost all do the equation changes. This is because a UPS loses energy in two ways – proportionally and fixed.4  Proportional losses occur in the form of heat-dissipation and are directly tied to the size of the load.  Fixed losses, however, remain constant regardless of how much current is running through your UPS. When a UPS is running a partial load, fixed losses have a more significant impact on its efficiency. This is especially important when you consider that most facilities operate their UPS’s at less than half of their load capacity. Efficiency generally drops off when the load is less than 50 percent of UPS capacity and drops substantially when below 30 percent of capacity.”

Signs Your Data Center UPS Is Not Running Efficiently

UPS EfficiencyOne of the most obvious signs your UPS system is not running efficiently is load capacity testing.  As aforementioned, if your UPS is running at less than 50 percent capacity, or even worse, at less than 30 percent capacity, your UPS is not running efficiently and is likely costing you more in energy than you should be spending.

Fortunately, many modern UPS systems have built-in alarm systems to help alert you to possible concerns.  Though it is important to note that you should not depend on the alarm system, you must still be routinely monitoring your UPS.  Many alarms will alert you to problems as they begin to develop before it is too late.  For example, an alarm might let you know your fan is not functioning properly or that your battery is in bypass mode.  If you see these issues, it is important to remedy them quickly before an outage occurs.

Another way to maximize your UPS efficiency is proper placement.  Your UPS system needs to be installed in a cool and dry location with plenty of ventilation.  The warmer the environment is in which you place your UPS, the more rapidly your battery life will diminish.  While the location should be cool, it should not be moist.  When you are able to control these factors and facilitate the most optimal conditions for your UPS system, its life expectancy will be far closer to manufacturer specifications than it would be otherwise.

Additionally, keep in mind that if your load has changed significantly since you installed your UPS system, it may be pushing capacity limits and may need to be sized up to accommodate your new needs.  As mentioned, if not sized properly it could over-tax the system and lead to a UPS failure when it is needed. 

By giving your UPS system the most optimal conditions you can provide, as well as properly maintaining it including cleaning, testing, and monitoring, you maximize efficiency and are able to significantly extend the lifespan of your UPS and therefore improve your total cost of ownership.





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