How to Size a UPS: A Guide for Non-Experts

To size the UPS: List all the equipment and devices you want the UPS to protect. List the amps and volts for each device. ... Multiply amps by volts to determine VoltAmps (VA). ... Multiply the VA by the number of pieces of equipment to get the VA subtotals. Add the VA subtotals together to get the total power requirement. More items... •

If you are someone who is not well-versed with technicalities, sizing a UPS can be a daunting task. But don’t worry, we are here to help. In this article, we will discuss some of the important factors that you need to consider while sizing a UPS.

Firstly, you need to know the voltage that your devices require. Is it a typical 120 volt that you plug into the outlet in your office? Or is it a 240 120? Maybe it’s a single phase or three phase? You need to know this information to correctly recommend the proper UPS for your needs. If you are not sure, ask one of your facilities people or data center people, they can give you that information.

Next, you want to allow for a little room for growth. You can take the voltage and on the back panel, you can see how many watts or volt amps the device consumes. Take that number times 1.2, and that will give you a starting point of how many volt amps or how many watts you need.

Secondly, you need to know the run time you need. The typical power outage in North America can range between 6 and 10 minutes, maybe 6 and 15 minutes depending on where you’re located. Identify what the typical outage is in your area, and don’t buy a UPS with an hour’s worth of runtime because that’s going to cost you a lot of money.

If you’re looking at a unit that’s going to power a number of different devices, make sure you have enough power to power those, and then check how many outlets you need on the back of the UPS. If it’s going to be set in a central location where the unit is going to be hardwired, and you’re hardwired into the unit and then to a small panel, that’s information we need to know as well. Is it going to be rack-mounted or floor-mounted?

Lastly, you need to know the topology of the UPS. Is it online or is it line interactive? Maybe standby depending on the type of equipment that you’re going to be providing backup for. There are a number of different pieces of information that we need, and we’ve got a document that you can email us, and we can help you identify the proper UPS.

In conclusion, sizing a UPS is not rocket science. You just need to know some basic information about your devices, and we are here to help you out. Send us an email with the necessary information, and we will help you find the proper UPS for your needs.


How to do proper sizing of UPS?
Because UPS systems are rated by VA or kVA ratings, this may require a conversion from W to VA, which can be calculated by dividing the power consumption (W) by the power factor. Add up all the VA, then multiply this by a figure such as 1.2 or 1.25, which factors in future growth and system expansion.
How do you calculate UPS load capacity?
Arrive UPS output power rating in watts = UPS output in volts-amperes × power factor. = 500 X 0.8 KW = 400KW.Arrive the nominal battery load in W.
How do you calculate how long a UPS will last?
If you want to know how long a given set of equipment will operate off a UPS battery, add up the current in amps that the equipment will pull and divide the amp hours of the UPS by that number. (e.g. A ½ amp load on a 2 amp-hour battery will run for 4 hours.)
How to size UPS for server room?
How Do I Size My Server Room's UPS? For IT applications it is a common practice for UPS systems to operate at about 50% (75% maximum) of its total capacity. To size a UPS, just simply add power ratings (Watts from the nameplates) of the equipment together then double it up.