need an UPS... - Page 1
Forum section: electronics / general

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 03, 2017, 07:10:37 pm
content: sorry i finish the school a long time ago.I need a new UPS. But how to calculate the max output power?I got 2 new Server where i dont know how many power the consume.Thx

author: Monkeh
author_rank: Super Contributor
timestamp: February 03, 2017, 07:33:06 pm
content: Quote from: Lord of nothing on February 03, 2017, 07:10:37 pmSafe way: Budget for the max their supplies can output.Practical way: Budget for 60% of that number.

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 03, 2017, 08:37:31 pm
content: oke the have 6x Power Supply with each ~2kva. I have just one Bladeserver in the Chassy and just one ~3HE Server.

author: amirm
author_rank: Regular Contributor
timestamp: February 03, 2017, 08:49:12 pm
content: That's a heck of a lot of power. Get a power meter and plug the equipment into them and see what they really draw.

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 03, 2017, 08:51:34 pm
content: Sadly i need some PDU before i could power it up.I dot want run a (working) server without an ups.http://ftp.assmann.com/pub/DN-/DN-95408___4016032339373/DN-95408_datasheet_Datasheet%20English_20140110.pdfDN-95408 so 4000W are enough I think?

author: Halcyon
author_rank: Unknown
timestamp: February 04, 2017, 12:28:50 am
content: You can also use the various 'calculator' tools available on the net. This will give you a rough idea of what to expect in terms of runtime.APC:http://www.apc.com/us/en/tools/ups_selector/Eaton:http://powerquality.eaton.com/UPS/selector/SolutionOverview.asp?resetCID=1

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2017, 12:29:12 am
content: How big is the chance of a power outage? If less then once a year then a UPS will cause more outages than it prevents.

author: BradC
author_rank: Super Contributor
timestamp: February 04, 2017, 12:45:49 am
content: Quote from: nctnico on February 04, 2017, 12:29:12 amI can't even come up with a polite response for this comment. If you have those issues with your UPS then you're doing it wrong.

author: Halcyon
author_rank: Unknown
timestamp: February 04, 2017, 01:10:32 am
content: Quote from: nctnico on February 04, 2017, 12:29:12 amYeah... I'm not quite following your logic on this one? Most decent UPSs do more than just keep equipment running during blackouts, they also cop surges, perform buck/boost functions and iron out line noise.

author: Red Squirrel
author_rank: Super Contributor
timestamp: February 04, 2017, 01:27:19 am
content: Use a clamp meter or a killawatt to get a general idea of the kw usage of all your stuff. When buying a UPS don't go by VA but by watts. Because of power factor and stuff the VA rating of a UPS will be higher than the actual watt rating, which is what really matters. It seems to be consistent though, a 1000VA is usually 600w.A typical 15a power outlet will output a max of 1800w, so if you get a 1,500w UPS you should be pretty good. If you have more than 1,000w of stuff get two UPSes. Once you get into UPSes that require more than a 15a outlet it gets expensive fast so it may be easier to split stuff across two.An inverter-charger may also be of interest if you want more uptime. It is basically the heart of a UPS, but you connect your own batteries - much larger ones. A have a 12v 750w Tripp Lite with 4 100ah deep cycle batteries for my home server room. Gives me roughly 4 hours of run time with a 400w load. It can possibly do more, but I've only had a few outages that lasted that long and after 4 hours I start thinking about shutting stuff down. The file server is the most important to keep up because a shut down risks damage to hard drives.I eventually want to upgrade to a dual conversion setup at some point though, but I also want to look into solar which would have very similar requirements (batteries, inverters etc) so I'll probably make it all one big project once I have money.

author: Red Squirrel
author_rank: Super Contributor
timestamp: February 04, 2017, 01:29:12 am
content: Quote from: Halcyon on February 04, 2017, 01:10:32 amYeah they can save you from power blips too like 1-2 second outages, which would normally cause computers to shut down hard, possibly damaging them. I've always said a UPS pretty much pays for itself the first time it sees an AC failure. Any important computer system should have one. Heck I even have one for my TV equipment. We don't really get much power outages but it's kinda like insurance on your equipment.

author: nctnico
author_rank: Super Contributor
timestamp: February 04, 2017, 01:56:30 am
content: Quote from: Halcyon on February 04, 2017, 01:10:32 amUntil they crap out and release the magic smoke. I went through several UPSses from several brands but if I add all the down time due to UPS maintenance or breakdown then my computer/servers have been more off due to the UPS related issues than power outages but I must say mains power is extremely reliable over here so I have not bothered using an UPS for over a decade now. Anyway, a good quality PC PSU and self healing (journalling) filesystems are the way to go.Also the line filtering is overrated because you'd need a very expensive ac-dc-ac inverter UPS which does that properly. I used to have one until it released the magic smoke because it couldn't handle switching on a load. Go figure...

author: rrinker
author_rank: Super Contributor
timestamp: February 04, 2017, 03:31:07 am
content: If each server has dual power supplies, then DEFINITELY get two UPS's, even if you don't need them for the total power - there's no point in having redundant power supplies if they are both powered from one common source. Should also have two PDUs. That way, if a power supply goes belly up and trips a breaker, it won't take out power to the second power supply in the same server, keeping it running. Each UPS should have its own circuit to two different breaker panels, too. And if you REALLY want redundancy - each panel should be fed by a separate main lead ins, although this isn't always possible. Best most people can do would be two circuits back to the same box, with each one on its own breaker. At that point you're pretty well protected.

author: Halcyon
author_rank: Unknown
timestamp: February 04, 2017, 03:31:31 am
content: Quote from: nctnico on February 04, 2017, 01:56:30 amTrue, but I'd rather my UPS release the smoke than my gear. We had an almost direct lightning strike here a few months ago. Thankfully all my equipment (apart from the modem and one of the NICs in my desktop machine) was fine. To me, a UPS is expendable, my data isn't and I'd rather not have to fork out cash on repairs and rebuilding machines. Even rudimentary protection is better than nothing at all.That said, I've never had a UPS just die for no apparent reason or due to some design fault.

author: amspire
author_rank: Super Contributor
timestamp: February 04, 2017, 06:00:50 am
content: Quote from: rrinker on February 04, 2017, 03:31:07 amThe theory sound good, but I am not sure it is a great idea.UPS's, especially quality UPS's are designed to safely absorb and isolate massive current surges on the input, but the protection is dependant on you not attaching any hardware powered by other mains circuits that have their own direct electrical or ground connections. Two UPS's connected to the one server definitely deteriorates the designed surge protection.Once you have two UPS's - possible on two different mains phases if they are single phase UPS's - and you ruin the surge protection. When a UPS Mains Input is absorbing a 3000A pulse, the UPS ground can temporarily jump to a significant voltage above the normal ground circuit. This is OK as long as it is the only ground in the circuit.Well designed UPS's do go to bypass if the UPS circuit fails so hopefully most UPS failures will not break the power.If you wanted to have two UPS's for greater reliability, you would probably want to put mains transformers before the two UPS's and hope that the addition of the transformers is not degrading the reliability. The transformers will have to be preceded by their own surge protection circuits and you will have to consider the transformer reliability.

author: Monkeh
author_rank: Super Contributor
timestamp: February 04, 2017, 06:07:57 am
content: Quote from: amspire on February 04, 2017, 06:00:50 amThis is why you ensure there's a solid ground path between them..

author: james_s
author_rank: Super Contributor
timestamp: February 04, 2017, 06:23:25 am
content: I gave up on UPS's at home after coming home to a burning smell and finding the older TrippLite UPS on my main PC melting and smoking. We had a small one at work catch fire a few years ago, fortunately it was during a weekday. A couple years after that we had a fire in the gigantic 3 phase UPS for the server room that resulted in the building filling with smoke and the fire department coming.Obviously there are situations where a UPS can be beneficial, but for home use in an area like this where power outages are rare IMO they're really not worth it. I'd rather replace a dozen fried PCs than have a faulty UPS burn my house down, but really I've only had two PCs die in the last 20 years and both were caused by a bad power supply that was easily replaced.

author: amspire
author_rank: Super Contributor
timestamp: February 04, 2017, 06:29:12 am
content: Quote from: Monkeh on February 04, 2017, 06:07:57 amIf the UPS company states this does not affect the surge protection. UPS's are not necessarily designed for very high surge currents between the output grounds of two UPS's.

author: Monkeh
author_rank: Super Contributor
timestamp: February 04, 2017, 06:31:04 am
content: Quote from: amspire on February 04, 2017, 06:29:12 amIf they can't handle that, they can't handle their own surge protection. At the end of the daytheir grounds are connected, via numerous random paths, making sure they don't end up with large potentials between them is not going to cause problems.

author: amspire
author_rank: Super Contributor
timestamp: February 04, 2017, 06:55:47 am
content: UPS have mains and ground outputs. If you just use those to power a server, you have no problem. If you connect the UPS ground back to another ground, then you have added in a problem. Industrial-sized UPSes can have an internal star ground point that can be directly connected to a big external ground busbar, but you cannot assume small consumer UPS's are designed to work this way. Often the only outputs are via male CIE power sockets.I have worked for a UPS company and you have to test for surge performance. I have never seen a small UPS tested in a pair with another UPS to check the output is safe if one of the UPSes gets a 3000A pulse and you have shorted the grounds together. If it is not tested, no-one knows how it will work till you get a strike at your site. Often, the UPS inverter neutral output is connected to the internal ground, and if the output ground circuit starts handling 3000A surge currents (rather then the input ground), the consequences are not trivial. In the case of a lightening strike, different grounds around a factory can be at hundreds of volts potential differences and so the idea is not to assume different grounds can be connected together.

author: Red Squirrel
author_rank: Super Contributor
timestamp: February 04, 2017, 07:13:45 am
content: Some of you seem to have very bad luck with UPSes lol. I've had some die on me too but I'd say they saved my ass more often than not.Though my ideal setup would be a 48v telecom style setup. I eventually want to do that. You have several AC-DC converters (usually we just call them rectifiers) that keep the batteries floating, then in the case of server stuff, have several inverters that run off the same bus. If the AC-DC part fails, whether due to power outage, brown out, or equipment failure, the batteries just carry the load. No relays, no switch over time, it's just instant. In telecom most equipment runs right off DC so even less stuff to fail.What would be interesting is to have several DC-DC power converters that produce all the voltages needed for computer equipment, then instead of fitting the systems with PSUs they would just have plates with the various voltage connectors on them that feed to the systems. I'm surprised this is not a thing in data centres. You could have a common 48v bus throughout the entire DC then each rack gets several power converters to do the 12v, 5v 3.3v -12v etc rails. The systems would just plug directly in. Of course each would have their own fuses and such.Oh and I second the idea of two PDUs on two different UPSes. Or in my case one PDU is on UPS and the other is on surge only. Most of the stuff is on the UPS PDU, but anything that has a redundant PSU has one plug into the surge only side. Eventually I will have two inverters so one for each PDU, then another inverter for circuits around the house.

author: Monkeh
author_rank: Super Contributor
timestamp: February 04, 2017, 07:15:11 am
content: Quote from: amspire on February 04, 2017, 06:55:47 amThat's.. kind of uncontrollable. Ground is ground, metal touches everywhere, cables have shields..If these devices you worked with separated grounds to this degree I'm not entirely clear how they could even be legal to install.

author: Red Squirrel
author_rank: Super Contributor
timestamp: February 04, 2017, 07:25:09 am
content: Yeah most UPSes will just pass the ground to the output ground.Now inverters are another story, need to watch out, some will actually work in such a way that the ground is actually in the middle of the AC wave but in a typical residential setup the ground is common to neutral. This can become an issue if you're doing anything like feeding your house with an inverter. I imagine most big inverters won't do anything weird with the ground though. Idealy, they should just let it float so it's up to the reset of the house electrical system to handle it.

author: amspire
author_rank: Super Contributor
timestamp: February 04, 2017, 09:31:13 am
content: All grounds are connected, but in the case of a lightening strike, a connection becomes an inductance and resistor. The ground on a UPS is momentarily different from the mains ground it is attached to. You get voltage differences between different grounds that are connected together. This is why ethernet adapters have a 1500V isolation. If all ground was always the same voltage across a building or a factory, you would not need isolation.

author: Monkeh
author_rank: Super Contributor
timestamp: February 04, 2017, 03:14:42 pm
content: Quote from: amspire on February 04, 2017, 09:31:13 amI understand this, and my point is that if the units cannot cope with a ground loop, they're faulty. Plain and simple. Theywilloccur, youcannotavoid them, and the only thing you can do to help is tie their grounds together properly. Even some of the cheaper desktop units have a terminal for this, and those which don't, you just connect the two outlet grounds together.Running redundant power supplies off a single UPS is hilariously stupid - even running them off two matching UPSes isn't too smart.E: Also, if one were planning such a setup.. they make much, much better surge suppressors than what you get in any UPS. Just fit those and this issue doesn't exist anyway.

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 04, 2017, 05:20:26 pm
content: QuoteThe same question like how often do you need the Airbag in your Car?QuoteYes here is the Network very bad. I dont know what my Dad did but you cant use Speaker who are Powered directly from the Socket. I use an UPS for my Pc System here.QuoteOMG what kind of crap did you buy? I use MGE/ Eaton UPS and some are realy old and the Work (sure I replace the Akku after a while)!Quoteno Fire extinguisher in the Rack?!

author: james_s
author_rank: Super Contributor
timestamp: February 04, 2017, 05:54:55 pm
content: Nobody is going to die if the power goes out and your computer loses power, comparing a UPS to an airbag is a little ridiculous, although I've always preferred older cars and never had one with an airbag.Of course we have fire extinguishers but this was a little beyond that. The UPS I'm talking about fills a whole room, the battery bank is the size of a small car. Are you going to run in there with a little fire extinguisher and no protective gear when the room is full of thick smoke? I'm not. Also it was after hours when the incident occurred and it set off an alarm.

author: madires
author_rank: Super Contributor
timestamp: February 04, 2017, 06:33:28 pm
content: Besides the VAs you also have to determine the run time you need. For my tiny data center at home I have a SOHO line interactive UPS for running a server and some network stuff including the PBX. Usually we have several short power outages during the summer caused by thunderstorms. The filesystem I'm using is quite resilient but I don't intent to rely on that only. Also the filesystem check would take a moment or two.

author: Lord of nothing
author_rank: Super Contributor
timestamp: February 04, 2017, 06:43:20 pm
content: QuoteJust for Shutdown. And saddly no i dont know how long it take becouse i never powered the Server up or install the Software because i have no power connection (yet).I was looked just on the Eaton Page and I found some:Eaton USV 9130 -> 103006437-6591 3000 / 2700 C20 (C13, (1) C19The Price is ok ~1000€ exkl Tax. In my Eyes the C20 Power socket is perfect.I know that I need at least 2 UPS Systems. 1 for the Server and another for the rest.