<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: arial,helvetica,sans-serif; font-size: 12pt; color: #000000'>Wow, the third paragraph on mostly went right over my head. I realize you were responding to a post, but is that esoteric background or do I need to wrap my head around it to decide what size UPS I need. Coincidentally, we also need a new UPS and we're trying to figure out exactly what we need. I don't have a Kill-A-Watt, but I see I can pick one up for ~$20 if it'll help. The blurb on it claims: <ul class="bulletList" style="margin: 10px 0px 0px 15px; padding: 0px; list-style-position: initial; list-style-image: initial; color: rgb(119, 119, 119); font-family: Arial, 'Helvetica Neue', Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);"><li style="margin: 0px; padding: 0px;">Large LCD display shows kW, volts, amps, watts, Hz and volt amps</li></ul><div><br></div><div>So how would I use that device, or another method, to size the correct UPS? And do I need to perform a calculation involving PI?</div><div><br></div><div>Scott<br><hr id="zwchr"><div style="color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>From: </b>"Alex Carver" <agcarver+ale@acarver.net><br><b>To: </b>ale@ale.org<br><b>Sent: </b>Tuesday, July 9, 2013 12:45:45 PM<br><b>Subject: </b>Re: [ale] OT need 600-1000W power protection for 3 minutes - cheap<br><br>I have three APC SmartUPS and have no problem whatsoever with apcupsd <br>finding them. I get emails when the system goes on battery and the auto <br>shutdown works fine across multiple machines with apcupsd sending data <br>to other machines hanging off the same UPS running apcupsd in ethernet <br>mode (no direct data connection to the UPS.)<br><br>Here's your BR/BX explanation: http://forums.apc.com/message/23515<br>The difference between the SMT and the BR/BX is the Smart Slot where you <br>can add Smart Slot accessories like various management cards (ethernet) <br>with temperature sensors, etc. Both the SMT and BR/BX have the normal <br>USB/serial data port for connecting to a single computer. The Smart <br>Slot just allows for direct ethernet connection and management by SNMP <br>and APC's PowerChute software.<br><br>Measuring in VA instead of W isn't marketing rubbish (entirely), it's <br>proper engineering specification for AC circuits. Unless your voltage <br>and current are exactly in phase at all times with no distortions at <br>all, Watts are meaningless unless you also specify VAr or the power <br>factor. Volt-Amps eliminates the need for the power factor because it <br>represents the scalar length of the power phasor (vector) regardless of <br>where it's pointing in W/VAr space (the 2pi radian range of phase angle.)<br><br>Using volt-amps for the specification means that a power supply (the UPS <br>in this case) can supply varying types of loads with different power <br>factors and the total available apparent power (real and <br>reactive/imaginary) is constant. A 100 VA motor and a 100 VA light bulb <br>require the same amount of apparent power. The light bulb needs mostly <br>real power and the motor needs mostly reactive power.<br><br>Where the marketing comes in is the fact that the engineers are forced <br>(by marketing drones) to pick an average power factor so they can label <br>the object. Typical switching supplies (prior to a concerted push <br>against manufacturers by power companies to make them electrically <br>cleaner) have a power factor of 0.6-0.8 and some really crappy Chinese <br>knock-offs have power factors down near 0.4 with hideous harmonics. APC <br>assumes a power factor of somewhere around 0.65 for connected devices <br>which is why your Watt rating is lower because some of the available VA <br>must be used for the VAr portion of the load demand.<br><br>On 7/9/2013 08:45, Ron Frazier (ALE) wrote:<br><br><br>> Hi all,<br>><br>> To be honest, I need to save some money for this project, since, when<br>> spending $ 200 at a time, and multiple times, it adds up. But, I hope<br>> to implement it soon. I might be able to buy one new unit, and reduce<br>> the load on one pc to use my old ups with that. Not sure yet.<br>><br>> The more I think about my loads, the more I think I need a 1500 VA / ~<br>> 900W unit. A 1200VA/~700W unit might do it, but most product lines seem<br>> to jump to 1500 VA after 1000 VA.<br>><br>> The last time I bought a UPS, it was from Frys. I have no complaints,<br>> but you do pay sales tax and probably an intrinsically higher price. The<br>> advantage is easier returns if needed. I can't believe it, but I am<br>> actually considering mail ordering a UPS. I understand from Amazon<br>> reviews on some, that you have to pay to ship it back to the factory if<br>> there is a problem, which can be expensive.<br>><br>> Based on prior discussions and my experience, I know APC is a good<br>> brand. I also understand that, for the "smart" units, it can be hard to<br>> get linux to talk to it, if you want to use the auto shutdown software<br>> like apcupsd. I think you guys told me before that Tripplite is good,<br>> so I may look at those. Based on some amazon reviews and prior comments<br>> here, it sounds like I should stay away from Cyberpower.<br>><br>> I think it's total marketing rubbish that they rate these things by VA<br>> primarily. My computer is currently pulling 539 VA and 532 W, according<br>> to the Kill-A-Watt EZ, with a power factor of .98. The UPS I have is an<br>> SMT-750 so you would think it could handle the load. But NO, that's 750<br>> VA. The watts are limited to 500, so the thing yells like crazy if I<br>> run this load on it. (So I don't.) So, it should be labeled SMT-500!<br>> That unit was capable of handling the load before I upped the load. Yes,<br>> I do know what VA means. It's just difficult to remember to cut<br>> whatever number I see on the box almost in half to get a realistic load.<br>><br>> Charles, thanks for the links. I'll keep the buy batteries local idea<br>> in mind. Might not be necessary with Amazon's free shipping.<br>><br>> It's nice to see that the major makers are starting to come out with<br>> some bigger units, with some smarts, with more reasonable price tags.<br>><br>> That Fry's link you posted is actually quite interesting. I found it's<br>> bigger brother on Amazon.<br>><br>> http://www.amazon.com/APC-BR1500G-BACK-UPS-10-Outlet-1500VA/dp/B003Y24DEU/ref=sr_1_1?s=electronics&ie=UTF8&qid=1373381258&sr=1-1&keywords=br1500g<br>><br>><br>> APC's different model numbers are confusing. For example, I don't know<br>> the difference between a BR and a BX unit.<br>><br>> This unit is a 1500 VA / 865 W unit, with lcd (or led or something)<br>> status display, and AVR (automatic voltage regulation [very cool]); for<br>> $ 179 with free shipping and no sales tax. This unit has a BR part number.<br>><br>> This is at a price point / capacity point that's really starting to get<br>> my attention.<br>><br>> Here's a similar unit at Frys.<br>><br>> http://www.frys.com/product/5955004?site=sr:SEARCH:MAIN_RSLT_PG<br>><br>> It has a BX part number. Go figure. The capacity is the same, but it's<br>> $ 210, or $ 225 after sales tax.<br>><br>> In any case, much better than the $ 500 Frys wants for the SMT-1500. So,<br>> I guess the big question is, what do I give up by going with the BR/BG<br>> 1500 and saving $ 300 versus the SMT-1500? I'll have to do some<br>> research on that.<br>><br>> Alex, good point about the cooling. If I'm using a stock battery and a<br>> name brand, it will probably be ok. If I'm using a non standard<br>> battery, that may be something I have to look at.<br>><br><br><br><br>_______________________________________________<br>Ale mailing list<br>Ale@ale.org<br>http://mail.ale.org/mailman/listinfo/ale<br>See JOBS, ANNOUNCE and SCHOOLS lists at<br>http://mail.ale.org/mailman/listinfo<br></div><br></div></div></body></html>