A
@operagost said:@asuffield said:APC just used to be really good, and now they're pretty unimpressive - they aren't worthless junk, but neither can you rely on them to soak up lightning strikes without tripping out, or smooth out noisy power to the point where your servers don't crash.I don't know if any UPS can take a lightning strike. I mean, it's only about a million volts.It's surprisingly simple to handle voltages on that scale. The basic construct is a widget known as a "spark gap". Basically, it's two heavy-duty metal prongs, where one is in the live feed, and the other is connected to earth. If an extreme voltage spike hits, over a couple thousand volts or so, then the air between the prongs ionizes and the whole thing grounds out to earth across the gap. A little gets past, but it's only about a thousand volts, which the UPS then has to soak. Ionized air will support any voltage that lightning could carry in the first place (since it's the same thing), and it's easy to build the prongs to the point where they don't melt. They're commonly used by the power and telephone companies to protect their own equipment, which get direct lightning strikes on a regular basis.It's actually more difficult to get rid of that last thousand volts than it is to ditch the first million. Heavy capacitors and trips are involved. APC UPSes manage to protect the equipment behind them, but their input circuit usually dies in the process, so your server shuts down when the battery runs out. A really good UPS will reset and keep going.As for smoothing noisy power, you would need to at least get into the Smart UPS line for true sine-wave output.They still don't manage to remove harmonic noise from the utility power. The smoothers in them just aren't that good. Hook up an old electric drill to the source, and the UPS output voltage will wobble all over the place. It doesn't help that the "Smart UPS" line is mostly only line-interactive, and not dual-conversion (although even their DC models still let noise though).