On 7/1/2011 1:02 PM, Brunner, Brian T. wrote: > centos-bounces at centos.org wrote: >> Brunner, Brian T. wrote: >>> centos-bounces at centos.org wrote: >>> >>>> And the APC Smart-UPS 750 units are not all that expensive >>>> either. Even the 1500VA units are a lot less expensive then they >>>> were 5-10 years ago. $250-$300 to protect $2000-$6000 worth >> of hardware is worth it in my book. >>> >>> To what extent does a UPS *protect* the hardware? >>> Maintaining up-time during brief brown-outs is one thing I expect of >>> a UPS,Orderly shutdown is another thing I expect of a UPS. >>> >>> *protection* of the PC from irregularity in the AC Mains by a UPS, >>> however, I question. Rather, it seems, any power irregularity that >>> would kill a PC by propagating through the PSU will also propagate >>> through the UPS. >>> >>> NO UPS MADE TODAY (according to my reading of the stats on >>> advertisements) eats lightning strikes and asks for more. >>> >>> So per your experiences and greater technical savvy: What PSU/PC kill >>> power irregularities will be stopped by which UPS? >> >> Really? That's what you read in the specs? > > Yes. Compare the joules rating (as being stopped by a UPS with surge > suppression) > to the joules required to damage the computer on the other side of a > PSU. > So per your experiences and greater technical savvy: What PSU/PC kill > power irregularities will be stopped by which UPS? > > Robert Heller suggested that UPS architecture matters: > AC->DC::DC Batteries::DC->AC > Where input AC is electrically decoupled from output AC. > Not many adverts for UPS's explain whether this is the case with their > UPS. > APC's SmartUPS line, Liebert, and Eaton Powerware are all true-sine wave UPS's, and do proper decoupling. Unfortunately, this kind of data doesn't make for great ad copy, so it's left out, and you have to dig deep into datasheets to get that information. I pretty much only use APC, and we have truly crap power here. Because of some heavy industry in the area, brownouts are common, and that'll kill a PC power supply better than anything. I've pulled one 7 year old APC from a server closet where the lightning took the top of the telephone pole OFF. THE UPS was fried, some of the breakers in the building were fused (!), but the servers were fine, outside of the router that got zapped from the DSL modem. The advantage to better UPS systems is they dump the input power through a big, beefy transformer. That provides enough of an inductor that it can eat a HUGE surge before the insulation in the transformer breaks down and it arcs across to the output. Even then, it has a long way to go before it can hit the output circuits. So, your cheap $100 UPS won't provide as much protection from a nasty spike, but it would be VERY rare to see a spike that big. >> Here, I thought that good quality surge protectors would do that, >> and my UPS does says surge protection as well as UPS. IIRC, UPSs, and > better surge >> protectors, offer a multi-thousand dollar warranty if it doesn't stop > a large >> surge and your system's fried. > > Have you tried collecting on said warranties? > Be prepared to prove that the surge that fried your hardware did not > exceed the joules rating on the surge suppressor. > And that's why you don't go cheap on your UPSs. Overbuilding capacity means you get a longer run time - and you also have room for expansion. Cheaper to go big early. > > Insert spiffy .sig here: > Life is complex: it has both real and imaginary parts. > Life is not measured by the number of breaths we take, but by the > moments that take our breath away. > > > //me > ******************************************************************* > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom > they are addressed. If you have received this email in error please > notify the system manager. This footnote also confirms that this > email message has been swept for the presence of computer viruses. > www.Hubbell.com - Hubbell Incorporated** > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos > -- Jim Nelson Systems Administrator, Broadtime (888) 582-3229