Quote:
Originally Posted by Brian Carlton
It's a "Back-ups pro 650". Not quite as big as the one in the picture, and it weighs about 40 lb. I selected it to run the computer and the monitor..........and it appears to be fine for that. However, I'm not understanding the lack of capability to handle a line voltage drop without a reboot of the computer.
|
Switching power supplies (the type used in PC's) must have a continuous input wave in order to produce output. In other words, they don't have the "flywheel effect" that analog power supplies had. If a switching power supply loses the input wave for as little as a half cycle (that's 0.008 seconds), that can be long enough for the power supply output to drop low enough to cause the computer to reboot. Basically, a momentary interruption of the AC waveform may not leave the UPS enough time to sense the drop, kick in the relay, and start outputting sinewave (or something close to it) before the computer's power supply stops putting out its DC voltages. In some cases, a small UPS with a small but fast relay may protect against momentary voltage drops better than a big honkin' UPS with a bigger but slower relay.
(That explaination paraphrased from Richard Oldenburg, co-inventor of the switching power supply).