UPS For Telescope, Cameras, PC, etc

[rogerg]

Hi all,

Can anyone with electronics knowledge clarify for me whether a pure sine wave UPS is required or will give any benefit over an approximated sine wave UPS for astronomical equipment.

The equipment specifically I am thinking of:
- Paramount ME
- SBIG cameras
- USB hubs etc
- Focus motors, dew heaters, etc.
- Network infrastructure
Everything above runs off transformers usually outputting 5-24v, so my estimate is that pure sine wave or approximated sine wave would make no difference as the transformer is going to smooth it out and convert to DC regardless.

Also running off it is a standard desktop PC.

I have always had my gear on UPS’s but am now looking at replacing the 13 year old units I have (batteries replaced several times).

Thanks,
Roger.

[ZeroID]

None of your gear list has critical sine wave requirements that I can see. They all use DC PS's in between the AC anyway so simulated sine is not passed through to affect devices.
Just ensure you have enough capacity on the UPS to deliver your required amps for your required time frame. Most UPS's are designed\specified to run long enough for a graceful shutdown on a server or PC and will require extended batteries for longer run times.

Good move on the replacement program, the electronics on these do age as they always have some load on them and the conversion hardware has also become more efficient.

My wife is the Branch Manager for UPS Power here in NZ selling Eaton UPS. We run a double online conversion 3kw unit on my sound system. Gets rid of all the annoying pops and crackles from the mains AC lines.
Makes for GOOD sound.

EDIT: Your normal UPS for PC use is only in a standby mode during use. It will be filtering any AC and giving some protection but the equipment will be only seeing normal mains AC unless power goes out. Then it will see UPS approximated sine to the DC PS's.
Only a double online conversion UPS ( AC > DC > AC ) as I use on the sound system supplies all AC all the time.

[rogerg]

Interesting, thanks.

Eaton are cheaper than the APC I’ve traditionally had. It is very hard to sort the wood from the trees and know what is good quality.

For example my three current top pics in no particular order are:

APC Smart-UPS C 1000VA/ 600W $482
http://www.megabuy.com.au/apc-smart-ups-c-1000va600w-lcd-line-interactive-ups-p390120.html

APC BR1200GI 1200VA $350
http://www.megabuy.com.au/apc-br1200gi-1200va230v-power-saving-back-ups-pro-p217876.html

EATON 1200va $221:
http://www.megabuy.com.au/eaton-5s1200au-usb-1200va720w-line-interactive-ups-p376915.html


I will be buying three of whatever I get, so the saving of the Eaton is considerable if it is actually going to be a quality product and provide the same level of protection as the APC BR1200GI 1200VA $350.

Back when I last looked at UPS’s they talked more about having full time surge protection and other features I don’t recall. Seems harder to differentiate them right now.

[Edit: I see now that the EATON is square wave, the APC BR1200GI is approximate-sine-wave, and the APC Spart-UPSC is sine-wave and Line Interactive. I guess that's the price differentials explained.]

[ZeroID]

Eaton put equipment on the Shuttle and ISS, race cars, truck turbos. The biggest my wife has sold is 80 kw, double online conversion. She used to be the APC NZ manager for about 8 years. She reckons Eaton are better. Been there just over two years now and APC in NZ are noticing her presence considerably. Eaton do the really big UPS's for Power stations, engineering construction. Her boss just installed 3 x 400 kwatt units, 1.2 megawatts in one installation.

Eaton do Line Interactive as well. LI means the UPS will intervene for small but significant drops or rises in voltage or frequency whereas the normal Standby UPS only acts if power drops out completely.

I'll ask her for a product number for an Eaton equivalent with Approx sine wave if you like, 1.2 kwatts ? from the APC #. I don't think Eaton do a 'square wave', it's actually stepped square wave which is ... approximated sine wave. Thats how it works but remember it is smoothed afterwards by caps and stuff. Number of steps is more important, the more the better the approximation.
'Square' vs "Approximation' is more a terminology difference, APC have their own 'language', Liz still uses it.

Eaton units also more efficient, conversion rates around 97% for smaller units like 1200 watts.

[ZeroID]

OK, just checked your Eaton selection on Megabuy. Go for it. Even I would guarantee it ! Line Interactive, better than 97% conversion, I'm waiting for one to come home ( at employee price of course :D ) for my home PC.
Not sure how warranties work in Aust but batteries are guaranteed 3 years here and normally last 5 or more easily.

:thumbsup:

[g__day]

A little bit of Lingo that I discovered a few years ago when I was madly purchasing UPS (have 10 of them now). Online, Smart and Backup in the naming.

Only the Online UPS (which is always the more expensive amongst the three) runs gear off the batteries 100% of the time. So for an Online UPS mains power is always charging the batteries. The inverted battery output is always independentally running your gear. So in the case of a brownout or power issue - with an Online UPS there is no switch over from filtered mains to battery to supply juice to your equipment.

For the other two types of UPS the mains normally feeds your gear - thru filtering circuitry. In the event of issues these UPS's can switch over to the battery and start inverting to supply juice. The switchover from mains to battery is a (?) risk point that you pay extra too avoid with an Online UPS is my laymans understanding of how the theory goes. So my astro gear is on an Online UPS and all the rest is on Smart UPS.

[NQAstro]

Hi Roger

I would have to contend. A square wave inverter will produce harmonics and they be passed through to the AC-DC transformer, even a PI or LC filter will not eliminate it. Pure sine wave inverters are also not 'Pure' they are synthesized and still have a certain degree of harmonics. Any sensitive electronic equipment may be susceptibleto the harmonics. I would suggest make a custom battery box with a deep cycle battery and a charger and run all your equipment directly from the battery and it will also act as a UPS. Only downside is u need 12VDC adaptors for your gear but i reckon it could be done cheaper then a UPS and it will last 10x longer then a UPS, especially if its 70AH or 100AH. The Battery being a massive resistor will clean up any harmonics that are coming out of the mains socket aswell. Cheers

[rogerg]

Brent - That's a vote of confidence, purchasing one. :) I have investigated the details of my existing UPS and they are the APC "stepped approximate sine wave". I am still a little concerned that the Eaton might be completely square not approximate and this might be an issue.

Chris - I'm not interested in the DIY approach although have considered the benefits of it as you mention - big battery, cheap. I want an off the shelf solution which will PnP with my PC to integrate with automation easily.

Matthew - Thanks for your input and clarifying those options. I think in this case the expense of "Online" is not warranted consdiering my old ones aren't "Online" and haven't caused significant problems.

[Paul Haese]

Hi Roger,

I have two Eaton UPS. One is EX3000VA and the other is EX1500VA. Both line interactive with double inversion. Both have in the past performed well but cost a packet. However, just something to consider. My EX3000 died a month ago because of humidity entering the unit. I am now having to consider what I will do to replace both units as both are exposed to high dew almost constantly. I looked into getting a 1000watt inverter with 150 deep cycle batter and a charger. Not cheap either but not going to break down because of dew either. Something to consider.

[rogerg]

Hi Paul,

Interesting. Perhaps in my situation I haven't come across such a problem because my UPS's sit in the inside half of my observatory which is relatively dry, clean and dust free. The new ones will sit in there also, so I think I should be OK. Worth considering.

Regards,
Roger.

[Paul Haese]

That should work for you. Worth doing something similar myself I think.

[ZeroID]

Eaton are built better, I've seen the real specs on these and they are definitely not square wave, guaranteed. Especially if you are going for the Line Interactive but even the under 1000va models. They match and maintain frequency to within a fraction of cycle, voltage remains at 231.2 + or - about .2 of a volt. APC are good but they are built high end consumer, Eaton are built industrial specs because Eaton are one of the biggest heavy electrical and engineering businesses in USA.

I'll send my wife over and she will tell you, she's been in the industry for 10 years and is the 'Queen' of UPS in NZ. A lot of her APC customers followed her when she changed jobs. Kind of annoyed APC somewhat.

[rogerg]

I decided to take a gamble on the Eaton (largely due to the enormous cost saving I have to admi) and ordered Wednesday night.

To my surprise they just turned up at my work! not bad for cross-country delivery :thumbsup:

[coldknights]

I got this ups for free a few days ago maybe a slight overkill !But there was no price tag attached and all the batteries are fine float voltage of between 12.99v and 13.20v and batteries had not been charged for a few days.

[ZeroID]

Geez Cathy !! Overkill is the word !!
Looks to be about 8-10 kva with plenty of runtime. Yuasa batteries are pretty darn good, reputable manufacture and those are big 'uns, 620 watts maybe.
Left over from a server room ?
That size needs to be hard wired in, not run from a 10 amp domestic plug. Charge and load current will exceed house wiring capacity if it comes off and back on after an outage. Is it 3 phase input or single ?
Can't quite read the manufaturers name.
What are you going to use it for ? What sort of load ?

[rogerg]

Well the Eaton UPS’s have been running since the weekend. It’ll be a few years before I decide if they are good or not (wait and see how durable they are). So far I am very much appreciating the modern interface – having windows know how long left it has on battery, and seeing on the LCD how many watts are being drawn and how long left etc is excellent. I don’t think I’d buy a UPS without an LCD now.