Back view of an Uninterruptible Power Supply

What Size UPS Do I Need?

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UPS is a device that guarantees that there will be no lapse of continuous AC power to the electrical devices connected to the grid when power is interrupted or unstable. Some UPS systems integrate surge protection to protect the attached device from current fluctuations or lightning strikes to guarantee a perfected current that is noise-free and free from voltage instability. 

Once you have decided to invest in a UPS the next thing to ask yourself is what size UPS will you need and where do you find one? 

It is best to find a company well-versed in UPS Systems with a good track record. There are, however, certain methods you will be able to put into place prior to shopping for your UPS so that you can choose the right size UPS for your needs. Knowledge is key and the more you know the better equipped you will be in finding the perfect size UPS for your equipment. 

  • List all the equipment that requires protection from dips and surges, brown-outs and blackouts 
  • It is important to include items such as monitors, external hard drives and routers as these also need protecting from unstable grid power 
  • The next step is to list the amps and volts of each device  
  • Most amps and volts ratings are found at the back of your electrical devices  
  • Multiply your Amps by Volts to get your VA (VoltsAmps) reading 
  • Some electronics list their power in Watts only 
  • These need to be converted into VA readings  
  • Divide the Watts by the power factor – an example is – Servers have a power factor of around .9 
  • Multiply the VA by the number of electronic devices to get the VA subtotals 
  • Add all the VA subtotals together 
  • Multiply the total by 1.2 to get the grand total (this step is important if you need to increase your UPS at a later stage) 
  • Use your grand total to choose the right UPS 
  • When investing in a UPS device remember to check the total VA requirement as this should never be more than your VA rating on the UPS of choice 

Use the grand total to select a UPS. Perhaps one of the most important points to consider when selecting UPS devices, be sure that the total VA requirement of maintained equipment does not surpass the VA rating of the UPS.