Pure Sine Wave UPSes for New Dell PCs
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From: who where on 11 Apr 2010 21:34 On Sun, 11 Apr 2010 06:46:38 -0500, "RnR" <rnrtexas(a)gmail.com> wrote: >On Sun, 11 Apr 2010 06:33:33 -0500, "RnR" <rnrtexas(a)gmail.com> wrote: > >>On Sun, 11 Apr 2010 10:00:18 GMT, "Brian K" <remove_this(a)hotmail.com> >>wrote: >> >>>Not that I'd do this but for my information could you run a 1500 watt heater >>>plugged into the battery side of a 500 watt UPS. I understand nice things >>>wouldn't happen if there was a power failure but would the heater run while >>>there was power? >>> >> >> >>"Great question" because for one, anyone might forget what the UPS >>rating is or might not realize what the item being used is drawing. >> >>My hope would be that in the event of a power failure, it would stop >>immediately having over powered the UPS and with no interuption of >>power just draw from the outlet. Of course I'm just guessing so I >>will hope someone with more knowledge can answer this. >>Any EEs here? >> >>Here are some links which may or may not help you and others about >>UPSs : >> >>http://www.atpm.com/13.02/ups.shtml >>http://www.jetcafe.org/~npc/doc/ups-faq.html > > >Here's another link which tries to answer your question .... >http://www.ptsdcs.com/whitepapers/12.pdf > > >I get the impression there is more than one answer depending on the >type of UPS used ... can anyone confirm this? Yes. As a long time industrial deployer of UPS systems, I deplore the terminology that appliance-style system suppliers have degenerated to, so I will avoid it. There are two basic types - those that activate the battery-powered inverter when_the_AC_supply_fails, and those whose inverter powers the load always. The first type supplies the load from the AQC supply when present, and does a quick transfer to the inverter when it fails. Overloading this type will - subject to AC load limits and protective devices - allow the load to be powered until the AC_fail/transfer, at which point the protection on the inverter output will halt proceedings. The inverter output protection on the true no-break type will object to overload from the outset.
From: Daddy on 11 Apr 2010 23:43 who where wrote: > On Sat, 10 Apr 2010 23:04:23 -0500, "William R. Walsh" > <newsgroups1(a)idontwantjunqueemail.walshcomptech.com> wrote: > >> Hi! >> >>> I think you are deescribing the"Kill-A-Watt". >> That's one (and it's the one I happen to have). There are some others that >> are stocked by major electronics and parts dealers, sometimes under a >> private label. >> >>> I know of a case where a UPS wouldn't supply juice if it wasn't >>> plugged into the utility mains. It was a "field day" exercise and the >>> intent was to power a WiFi repeater off the grid. >> That might be a safety concern (floating ground) or perhaps the unit was not >> cold start capable. Not all UPS units can start up their inverters without >> first being on AC power, but most can. Older APC units in particular won't >> do this--they must start from AC power first. > > Indeed. Lately I seem to be the mug that people with ye olde APC > units seek out to verify they work before spending on refurbing the > battery department. One unit - a 1995 SmartUPS 2000XL - required AC > before it would boot, whereas the next series (1999) SmartUPS 2200XL > will do a cold start if you know the technique. Why they aren't ALL > cold-start-capable beats me. Very interesting discussion going on here. I wonder who started it all? Oh wait...that was me. I've made a few decisions in my quest for a UPS. Decision number one is that no way am I going to spend $400 for a (properly sized) sine wave UPS for my $800 computer. That's plain ridiculous. In the unlikely event that a power blackout kills my computer, I'll pay a little more and restore my backups to a perfectly good $500 computer. Decision number two is that I am not going to take apart any lawn mowers or other appliances to cobble together a proper UPS on the cheap. A person shouldn't need to become Rube Goldberg just to protect their computer. Decision number three is that I am not going to pay any more attention to the half-truths and intentionally vague assurances provided by UPS makers. Decision number four is that I'm going to let a few select people at Dell and APC know that its only a matter of time before Joe Consumer figures out what's going on. Finally, decision number five: I'm going to buy myself a properly sized stepped approximation UPS with the shortest transfer time I can find for as cheap as I can. In my area I'm not too worried about blackouts. Daddy
From: William R. Walsh on 12 Apr 2010 11:43 Hi! > I've made a few decisions in my quest for a UPS. Decision number > one is that no way am I going to spend $400 for a (properly sized) > sine wave UPS for my $800 computer. When I was in the market for a new battery for one of my cheap-o APC plugstrip UPS units, I turned to eBay as there is no sense in paying $30 for a battery when that's what the UPS cost! The seller had an APC Smart-UPS 1500 for sale, listed as refurbished, that they asked (and received) $75 for. This UPS has true sine-wave output. (And in the case of the one sitting next to my desk, it was made in the US. Yes, I think that counts for something.) > Decision number two is that I am not going to take apart any > lawn mowers or other appliances to cobble together a proper > UPS on the cheap. That's not what I said. :-) I suggested that if you really did need a UPS with true sine wave output, that a lot of them could be found for *nothing* if you'll haul them away. That's because the batteries are invariably bad, and replacement batteries that carry the UPS manufacturer's seal of approval are (very) expen$ive. There's nothing cobbled together about it if you do it right. I only suggested it as a possibility in case the price of a new unit with a good battery was especially offputting, as it seemed to be. > with the shortest transfer time I can find for as cheap as I can. Be careful, there is a point where that number might devolve into what is technically (!!!) referred to as a "fib". If you find one that is leaps and bounds shorter than anything else you see advertised, it's reason to be suspicious. William
From: Daddy on 12 Apr 2010 11:49 William R. Walsh wrote: > Hi! > >> I've made a few decisions in my quest for a UPS. Decision number >> one is that no way am I going to spend $400 for a (properly sized) >> sine wave UPS for my $800 computer. > > When I was in the market for a new battery for one of my cheap-o APC > plugstrip UPS units, I turned to eBay as there is no sense in paying > $30 for a battery when that's what the UPS cost! > > The seller had an APC Smart-UPS 1500 for sale, listed as refurbished, > that they asked (and received) $75 for. This UPS has true sine-wave > output. (And in the case of the one sitting next to my desk, it was > made in the US. Yes, I think that counts for something.) > >> Decision number two is that I am not going to take apart any >> lawn mowers or other appliances to cobble together a proper >> UPS on the cheap. > > That's not what I said. :-) > > I suggested that if you really did need a UPS with true sine wave > output, that a lot of them could be found for *nothing* if you'll haul > them away. That's because the batteries are invariably bad, and > replacement batteries that carry the UPS manufacturer's seal of > approval are (very) expen$ive. > > There's nothing cobbled together about it if you do it right. I only > suggested it as a possibility in case the price of a new unit with a > good battery was especially offputting, as it seemed to be. > >> with the shortest transfer time I can find for as cheap as I can. > > Be careful, there is a point where that number might devolve into what > is technically (!!!) referred to as a "fib". If you find one that is > leaps and bounds shorter than anything else you see advertised, it's > reason to be suspicious. > > William William: About the lawn mover...I was just making a joke. Daddy
From: William R. Walsh on 15 Apr 2010 09:44
Hi! > Why they aren't ALL cold-start-capable beats me. Because that costs extra money...! (I do mean that seriously, as I doubt the majority of end-users are going to be cold-starting their UPS for a few minutes of computing.) It is a nice feature to have when you've got nothing else. I'll admit that I've turned on an old APC UPS on line power, took it off line power and used it to charge my cellular phone while on the go. What can I say? It worked and I couldn't find my car charger. I'm proud of this in a nerdy sort of way. :-) Fortunately, it seems that most UPS units are now being made cold start capable. Even some of the cheap APC plugstrips can be used this way. William |