Uninterruptible Power Supply Protection for your PC
You are sitting at your computer, feverishly trying to finish your ten-page report that is due tomorrow. Unbeknownst to you, five miles away in the next county, Johnny Teenager is trying to text his girlfriend as he drives down the road to her house. The good news is that he got his text message off. The bad news is that he missed the turn and took out a power pole before he came to a stop.
You are about to write the last sentence, when without warning – Blam! The power goes out! Sitting there, fingers in mid-stroke, you suddenly realize that you did not save your document! The only good thing about the darkness you are sitting in is that you can’t see the note you left on the desk the last time the power went out—“Turn on Auto-save”!! Which, of course, you didn’t do
The Power Problem
Power line incidents happen all the time. By some estimates the average home owner will see about 120 line voltage related incidents per month—about 4 per day! (That’s average, which means that some areas are worse than that.) It doesn’t have to be a break in a line to cause an outage. Lightning strikes can overload the grid and cause circuit breakers to open the lines; everyone turning on their air conditioners at the same time can overload the grid causing the power to drop; or somebody in your home turning on the microwave and the toaster oven at the same time can cause the circuit breaker to trip, taking your computer down because it was plugged into the same circuit.
In the nasty world of electrical power, your computer is vulnerable to damaging transients, overvoltages, brownouts, dropouts (especially when they occur in rapid succession over a few seconds) and just plain noisy line voltage.
The Power Solution
“What’s one to do?” You may ask. Have you considered using a UPS?
No. That’s not the delivery guys in the brown trucks, but: Uninterruptible Power Supplies. A UPS, can provide your system with more than just battery backup, they can protect your system from the ravages of the real world electrical power grid.
The power supply in your computer or the wall supply used by your laptop converts the AC line voltage (typically 120VAC or 240VAC) to a direct voltage your computer can use (typically +3.3VDC, +5VDC and +12VDC). The integrated circuits (IC’s) you have in your computer have a very low tolerance for voltages that deviate beyond these typical values. Lower voltages will generally cause your system to lock up and/or crash while higher voltages can destroy the IC’s in an instant. The power supplies that power your systems have been designed to handle a certain level of noise and variability on the AC mains. They can only tolerate so much before they may quit doing their job providing regulated DC voltages and your computer suffers the consequences.
In all cases, the batteries are continuously charged while the UPS is connected to the AC line. Once the UPS detects a low AC line voltage it will switch over to the battery supply (except the On-Line UPS that is always running off the battery) and power your computer for a period of time that will depend on the size of the UPS and your system.
For a typical desk top system and monitor, the power draw is about 70 Watts (about 98 VA) and a 350 VA UPS would provide about 14 minutes of backup time, while a 550 VA UPS would provide about 30 minutes of backup. (Note that the 350 VA UPS would provide about 2.5 minutes of backup time if it were fully loaded at 350VA.) Of course, the longer the backup, or the higher the VA rating, the more you will spend to provide the desired protection.
In addition to providing clean power to your system, a lot of the UPS units provide transient protection for your phone lines and network connections and with a USB connection and appropriate software installed on your system, your computer can power-down safely, unattended, in the event of a power failure when you are not there.
Uninterruptible Power Supplies can provide you with another level of protection from the “elements” and you may want to consider them if you cannot afford data corruption or loss of hardware due to beasties that inhabit the power grid.