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January 0, 2017 | Rob Hirschberg

What UPS System Is Right For Your Backup Power Needs?

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Are you aware that UPS systems come in 2 different operating types?  They do, and we’ll define those right now so you can insure that you have the correct backup system in place for your needs.

Let’s take a quick look at how a UPS operates:

An interactive or “online” UPS takes the AC power from the utility/house, and converts it to DC.  The converted DC power is used to power the inverter section of the UPS and to charge the batteries that are used to run the inverter when the AC power is lost. 

The DC power runs the inverter that converts the DC power back to AC power that is filtered and regulated.  This power runs the computer or the load connected to the UPS.  The UPS also has a static switch built into it. In the event of an internal failure, the static switch will switch over to the power-line and bypass the inverter and batteries to keep the computer running while sounding an alarm.  At this point, there is a failure in the UPS that needs to be repaired but you still can operate as is because the machine is plugged into the wall outlet.

In the case of a non- interactive or “offline” UPS, the Inverter does not run all the time and must start up to take the load in the case of a power failure or power problem.

Standby UPS ---- Non-Interactive

These are normally the UPS systems sold in the big box retailers for use under a desk or at home on a small computer.  These UPS systems stay in "stand-by mode", even though they are plugged into the wall and the computer is plugged into the UPS.  In the event of a power failure, the inverter portion of the UPS has to start up and develop the AC power to run the load (normally a computer).  The problem here is that the latest computers will fail with as little as a 3 microsecond power loss (remember that electricity travels at 186,000 miles per second). To your computer, 3 microseconds is an eternity!   It’s almost impossible for an offline UPS to react in this period of time.  So what happens?  The computer reboots and whatever is in process is lost ---- permanently.

Online UPS – Line Interactive

The online UPS does not have to start up anything because the inverter is already running, the batteries are online all the time and there is NO interruption to the computer’s power stream.
This results in no lost data and no work in progress loss.

– These are the same type of UPS systems that are running in data centers and, most likely, in your business.  They’re reliable, they reduce downtime and are about 99.9% capable of supporting your systems with a high level of reliability.


If you’re just concerned about your home computer then the small, cheap UPS from the big box store might be okay, but If you operate or monitor your business from home, that's another story!  Go ahead and get the line interactive unit from a supplier in which you have confidence.  

I’m asked over and over, what UPS system do you recommend or use.  My standard comeback is that there are many good manufacturers of Interactive UPS systems in the market today.  My personal choice is the Emerson GXT for my home computer and office computer systems.  We even have one on our phone system in our small office in Memphis and they have never let us down.  

Whatever the case, insure that you get a UPS system sized to your load or the amount of power you will be drawing from it.  Also remember that a UPS should NEVER be used to run any type of load like a power tool, an air conditioner, or anything that we term as an “inductive” load - it will not work.

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