It’s a normal day, as you are reading this blog — your spreadsheets open, a design half finished, an email half written on another tab. What happens if your power goes out on your PC? Thanks to the work of Microsoft and Google, probably nothing. But what if the PC is operating on a factory floor or lies at the heart of a data logging, security, or medical embedded application? Data can be lost, sensitive equipment can be damaged and time is wasted. An Uninterrupted Power Supply (UPS) is a solution. But with so many options, it’s hard to know which option is best.

What is a UPS

At the core, a UPS is a secondary power source — a battery — that connects to a system to take over in the event of a change in power. They come in three general categories, or modes, each with their own purpose.

Offline/standby – This is your most basic UPS, giving you surge protection and battery back-up. They have a switch that triggers when power is cut off and brings the system onto battery back-up usually in a few milliseconds. This is fine for most PCs, routers, firewalls and the like, but can cause data errors if the machine is running a particularly intensive process, like rendering video.

Line Interactive – These UPSs are popular in areas where power fluctuates. A line interactive UPS can sustain a continuous under voltage (brownouts) and overvoltage situations thanks to a an autotransformer that compensates without tapping the battery. However, the voltage adjustment can cause power momentary irregularities that can affect sensitive devices like medical equipment, precision measuring tools and the like.

Online/double-conversion – The Online UPS is a ‘must have’ when no variation in power can be allowed. In these UPSs, the battery is connected into the current constantly and, when power changes occur, there is no effect on output. The primary downside to these is that the batteries can take more wear and tear and require replacement more frequently, but they are the best choice when system stability is at stake.

Battery back upOffline
BrownoutsLine Interactive
Always onOnline
Case in Point: At the 2013 Super Bowl during the live telecast a massive power outage hit and shut the game down. Along with the game went computers throughout the stadium, including those belonging to a photo vendor who’s photographers were processing photos for immediate release to international media. Normally racing against the clock, their productivity came to a sudden, grinding halt, and all work was lost. When the power came back up, they were left starting over again from scratch. 

How do you pick a mode?

Making the move to a UPS, is sometimes a tough sell, at least before a disaster. It’s important to look at your use case and decide. Does your factory have an initial power draw when line starts up? You will want a line interactive UPS to prevent damages to your PCs. Do you have an older manufacturing machine that occasionally blows a fuse? A battery back up will save you from losing data. Are you running delicate and precisely calibrated sensor equipment? An Online UPS will prevent them from becoming inaccurate.

The Takeaway

When thinking about how to fail-proof your system, especially in harsh environments, effort is often made to go fanless, and remove vents from a system. That’s a clear start for maintaining the life of a system, but UPSs are often an afterthought, or worse never thought of until a failure happens. The time to think about a UPS is before you need one!

Note: This blog was originally posted on November 11, 2013. It was updated on June 11, 2020. The original post highlighted the use of an in-PC UPS. This type of UPS is no longer recommended by OnLogic. 


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