Originally Posted by jimmie
But I am still a bit puzzled why my computer lost power and the screens went black, when I still had electricity at the office. I could understand the battery failure beep indicator on the 600 APC device going off, with just battery failure alone but why the loss of power to the computer? Would a computer lockup manifest this way?

Hi jimmie,

Here's my guess. a UPS will have 2 ratings. One is for the available power when on battery backup. This may be, say, 300 watts (watt=volt X amp, so 300 watts = 300/120 or about 2.5 amps.)

The second is total output when on AC power, which would be the total of what is plugged into the battery backup, and the surge protector outlets. Lets say this rating is 12 amps. If the computer and monitor take 2 amps, and the laser printer 10 amps, then the 12 amps could be met or exceeded. Then an internal circuit breaker (in the UPS) could have tripped.

So why at that particular time? Either one of the devices took more current, or the "trip curve" of the circuit breaker would allow a certain current for a certain period of time, and the time was exceeded.

In either case, an internal circuit breaker would open, and any devices plugged into either side of the UPS would go dead.

The circuit breaker sometimes resets automatically, sometimes there is a button for you to press to reset.

Or, the UPS is starting to go bad.

So the computer is an "innocent bystander."

Make sense?

Gene

Gene Nallin MD solo family practice with one PA Cumberland, Md