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What is an Uninterruptible Power Supply (UPS) and do Law Firms Need Them?

TechnoLawyer wrote:

"What is an uninterruptible power supply (UPS) and do law firms need them? How about a generator?"

Uninterruptable power supplies (UPSes) are a requirement for protecting hardware and data integrity. ALL law firms should use them, if only on their servers.

As most people know, desktop PCs and servers run off alternating current (AC) provided by the electric company. What many people don't know, however, is that AC power is subject to flucuations short of a full blown blackout that can damage equipment and cause data corruption. These power flucuations can take the form of brownouts, minor power dips, small power surges or spikes, and undesirable line harmonics. None of these is good for sensitive electronic equipment like your computer. You plug your equipment into the UPS, which in turn is plugged into the wall. Good UPSes "condition" the AC power coming out of the wall before it gets to your computers so that they never see these power flucuations.

There are three kinds of UPSes:

Standby or failover UPSes. These are not truly uninterruptable. These work by using AC power from the wall to charge batteries. If the AC power goes out or dips below a threshhold, the batteries kick in to provide power to your equipment. There is a "slight" lag between the time the AC fails and the batteries come online. (The DC power from the batteries goes through an inverter to be converted to AC power before being sent to your computer.)
Hybrid. These use a transformer to maintain a constant AC output, while also charging backup batteries. If AC fails then power comes from the batteries. As with standby UPSes, there is a slight lag between the time AC fails and the batteries kick in.
True uninterruptable power supplies. In true UPSes, AC power from the wall outlet is used to charge batteries. Power is then taken from the batteries, piped through an inverter, and output again as AC for your equipment. Because the batteries are always in use, there is no drop in AC output while the UPS switches its power source from the wall to its batteries.

Because there is NO interruption when AC power fails, true UPSes are by far the most desirable. The kinds of power flucuations that a true UPS protects against can damage electronic equipment, including your PC, server, and networking gear like hubs, switches, and routers. They can also cause data corruption or loss. Standby and hybrid UPSes don't provide the same level of protection against power interruptions as true UPSes.

At a minimum, I recommend that your servers be put on UPSes. If you save your data from your desktop to your server often, you can get by with just surge suppressors on your desktops, although UPSes are preferred for them, too. If you don't have a separate file server, I'd put your PCs on UPSes.

Note that UPSes and surge protectors work ONLY if your wall outlets are properly grounded! Even if you have three-prong outlets it's possible they are not properly grounded. Thankfully, it's easy to test this. You can buy a ground tester at the hardware store for about $5-$6. All you need to do is plug it into an outlet and going by which LEDs light up, you will know if your outlet is properly grounded or not.

Most UPSes can also be connected to your computer with a serial or USB cable. In conjunction with software, the UPS will then properly shutdown your computer a set time after the AC power fails (unless it is restored), preventing data corruption due to an improper shutdown.

In my opinion, most law firms probably don't need generators, unless they are in an area with frequent blackouts.

Here are a few manufacturers of UPSes:

American Power Conversion: http://www.apcc.com
Belkin: http://www.belkin.com
Tripplite: http://www.tripplite.com/

APC and Tripplite both provide online guides to selecting a UPS which can provide enough power for your needs.

This article originally ran in the TechnoLawyer list on 9/24/03.