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Hema
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Joined: 11/05/2007
Location: Finland
Posts: 2

Posted: 03:53pm 10 May 2007

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Hello DIY wizards ...

I have a following situation:

I have a summer house and to I want to set up a wind generator to get 240V AC to run lights, warm water and other conviniences there.
The original plan is to purchace a factory wind generator and all related kit from the local company, but as I was browsing thru the net I noticed that the inverters are pretty expensive. I would rather invest more to the battery packs and to the generator itself and use the spare UPSes I have lying around as inverters if possible.

As said, I have 3 spare PowerWare 3000 http://www.powerware.com/UPS/9120_specs.asp UPSes and I would like to ask if anybody here would have an opinion or even better advice how to proceed. The kit is in working order, although the 120V battery packs are gone. I was planning to get something like 6 or 8 * 200Ah brand new batteries and maybe a Whisper 500 or the russian 5kW generator.

I have BSc in Electical Engineering, so I should understand the basics, but the 1.5 decades in IT have had their toll on my skills in that department.

I would very much appreciate any help and might want to set up web pages on the progress of the project if it flies.

Henrikki
Finland Edited by Hema 2007-05-12

brucedownunder2
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Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 08:34pm 10 May 2007

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Hello Henrikki,

I have a couple of ups's working nearly full time in my workshop from the battery bank . They have been going 5 years or more now . Actually measured the O/P yesterday , 239.8 V ,,so I'm quite happy with that. They power all the small'ish things around the workshop and lighting,but are a bit small (1000 watt and 1200 watt), for big motors and the refrigerators.

Mine work on 24v battery bank ,drawing quite a current at times ,so I use very large supply cables. Your 120 v dc supply cables can be much smaller ,but,,,, 120v dc is very dangerous, so you would be advised to treat this feed and the battery terminals very cautiously. Insulate everything and enclose the batteries ,even lock them away from wandering hands... Make absolute certain that you disconnect and seperate the battery cells before working on them.

They are good (ups's) ,,but if you don't have a small fan around the electronics then install one to move the warm air from semiconductors and the heatsinks.

good luck

Bruce

Bushboy

RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 03:24am 11 May 2007

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UPSs are less than ideal in my experience.

They have quite substantial "base load" requirements.

Some good quality pure-sine 1KVA units I have here suck more than my laptop and 21" external TFT monitor just in overheads.

I also have some misgivings about using UPSs purely as inverters - few seem to be designed to run in this mode on a continuous basis, although many seem to have managed it. One of my concerns stems from the built-in diagnostics and battery tests most do from time to time, and get all bent out of shape if things arn't as they expect. YMMV!

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 09:44am 11 May 2007

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G'day RossW,
You state that UPS are not ideal and that even good quality pure sine wave suck up heaps, but you do not say what it is that you recommend as better for our situation.

Please advise.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 10:11am 11 May 2007

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Sorry Gill, I didn't want to be mis-interpreted as a nay-sayer, or to have a particular barrow to push.

As someone who has been in the IT industry for neigh on 30 years, and had (has) a large range of UPSs from 600VA up to 45KVA, I feel moderately capable of commenting.

(Edited to add: those of us who are on, or have been on, grid power have little concept of just how power-hungry and wasteful a lot of this equipment really is! Plug in a UPS and think nothing of the 30, 50, 400 watts of "overhead" it takes.... then multiply that by the 6 or 10 you have on a site.... I recently measured one circuit at the office (small office, 5 staff) and found that the computers alone are taking 8KW (thats staff, customer access machines, servers etc) and "only" 3.5KW overnight! That'd absolutely kill me at home! That's 84KWH/day just for these "essential" machines! I manage to "get by" at home with low-power machines at 15KWH/day)

I now (and for the last 2.5 years) have lived in a home that is 100% off-grid. No connection to any external power at all.... yet for business reasons, I still run 10 or a dozen computers here at home, all the time.

Recently, I had a problem with the genset which resulted in a brief (half-second) interruption to the household power, and two of the "important" machines rebooted. Might I add, the only machines that were not either (a) laptop computers or (b) already running on batteries. This convinced me it was time to put a UPS on them (every other computer at every other site worldwide is on conditioned power, just that here was the one exception)

After plugging the first one in and measuring the standby power (and being horrified) I went through 8 or 9 others, and found they ranged for "scary" to "pathetic". Not one of them was sufficiently "efficient" for me to even consider leaving it running here, where every 10 watts counts.

I use a 5KW (continuous) inverter from Power Solutions Australia (no commercial arrangement other than I bought their equipment), off my 48V battery bank, and have done for as I said above, 2.5 years odd. The brief interruption was a PITA, but I don't think I can blame the inverter for this.

While the inverter does draw a reasonable amount, its overheads are modest. Certainly, less than any of the inverters I tried (and I used some from 600VA up to 5KVA, with varying degrees of horror!).

At the end of the day, I think you have to work out what suits you best. If you make enough power from RE (wind, solar, whatever) to cover your needs plus system losses, then go for it.

If you're like me, and still have to use alternative (expen$ive) sources, like a propane generator for 6 hours a day, then every watt you save is critical and pays for itself over time, then you should invest in a better inverter that saves you some of that critical power.

YMMV, everyone has different needs.Edited by RossW 2007-05-12

Hema
Newbie

Joined: 11/05/2007
Location: Finland
Posts: 2

Posted: 10:33am 11 May 2007

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I was theorizing that with a wind generator that provides 3 phase AC one could feed directly those all 3 UPSs. As they do both charging and inverting.
Then as they all would have separate battery packs, I would then create 3 separate circuits for lightning, fridge and wall sockets. I have no need for 3 phase so I would not need to bother syncing them, right?

An reasonable charging inverter such as OutBack VFX 3048E costs here $2500US so I would save a considerable amount of money. Specially as one would not be enough to supply sufficient power.

I do have a ~3kW Lister diesel generator for emergency and usage peaks, but connecting that to the system and fixing the automation for it is a completely different excercise.

Any comments ?

HenrikkiEdited by Hema 2007-05-12

RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 11:34am 11 May 2007

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You're thinking too theoretically and not sufficiently practically. Yes, 3-phase turbine could feed 3 UPSs, but UPSs are *designed* to have very narrow windows of "acceptable" mains inputs. Usually they won't operate more than 1Hz or so either side of their nominal frequency, nor more than about 10% from nominal line voltage. Your wind turbine certainly isn't going meet that specification.

As far as generators go, I'm not a good one to ask.

I took a 4-cylinder car engine, ripped off all the fuel injection, the computer etc. Replaced the cam angle encoder with a distributor. Put a single-point gas mixer in front of the inlet, added a lambda controller to ensure fuel mixture remains optimum, and built a small computer based on an atmel 90S8535 to do all the sequencing, engine management, interlocks etc to start, run it, control engine speed, water pump etc and coupled it to a 1500 RPM 14KVA generator to provide me with the 240V AC for backup and charging.

If you rely on this thing, especially if you have a family who won't "appreciate" that things go wrong when your UPS fails, spend the extra and get a tried, tested, solid inverter made for the job :)

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 11:35am 11 May 2007

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Thanks Ross, you sure raise some interesting points in areas I never gave much thought to.
Mostly I suppose because I reach for the best(biggerist & mostist)the budget will stretch to. And if there is no budget, what is scroungable to give me the biggerist & mostist. Seldom is there much choice, usually with demand having to downsize to meet supply.

Henrikki,
Are you sure the ups battery packs are 120V? I see that input is nominal 120v AC (range 80 to 144V), but are not the batteries sealed lead acid 12v DC or 24v DC?? The specs don't say.
I am not sure what wind gen outputs are available in Finland, but would need to be well regulated to maintain an output within the UPS 80 to 144v AC limit. I think this would be a most unlikely wind gen supply.

I think I would be checking the exact battery voltage of the UPS before considering further.

Those UPS seem quite good. One feature in your favor is "Start-On-Battery ----Allows start of UPS without utility input "
Which means that if your batteries are say 24V DC, you can bypass the charger circuit and charge the batteries direst from a 24V wind gen.

Also they are sine wave and with a fair efficiency of 86% to 90%.

Definitely need to check that battery voltage though.
Edited by Gill 2007-05-12

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

RossW
Guru

Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 08:44pm 11 May 2007

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Gill, Henrikki may well have 120V battery pack in his inverter. That's a moderately common value.

I've got a bunch of 3KVA to 5KVA units here at the moment.

The APC rackmount jobs have 8 batteries in series/parallel for 48V, while the newer Sola have 8 batteries in series for 96V. One of the other 5KVA units has 10 batteries in series for 120V, my old sola line interactive unit has 12 cells in series for 144V, and one of the bigger Merlin Gerin ran 204V (!!)

Ahhh, Standards, ain't they wonderful?! </sarcasm>

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