I need a UPS with pure sine wave output. When the specification says "pure sine wave" or "sine wave" (I've noticed e.g. APC uses word "pure" nowhere), does it mean the output is pure sine wave comparable with the utility power?

Or is the "pure sine wave" only a better approximation of a stepped sine wave? In that case what is the cheapest UPS with the best sine wave available?

thanx

What are you trying to do? Is this for Hi-fi A/V? Medical equipment?

I presume you already know that utility power is anything but a pure sine wave...

I work with ups's daily

Here you can see that there 'Pure' sine wave ups's aren't called it pure \/
http://www.apcc.com/resource/inclu [...] ku=SUA1500 - I love these, banks use them all around the world
http://www.apc.com/resource/includ [...] UA1000RM2U


Here you can clearly see that this isn't pure, it's Stepped approximation to a sinewave \/
http://www.apc.com/resource/includ [...] sku=BE550R
http://www.apc.com/resource/includ [...] _sku=BK350

Matter of fact, they don't even state 'pure' on their $10-20k ups's. If you have a problem with their style of naming, you can email them a complaint. Pure isn't a word manufactures have to use, some use it, some don't. In reality, there's no such thing as a trully pure sine wave ups. Find your nearest Electrical Engineering company or school and they'll be glad to explain this to you.
http://www.apc.com/resource/includ [...] watts=4000
http://www.apc.com/resource/includ [...] watts=2000

You don't necessarily need the best sine wave for general home pc's.

http://www.amazon.com/APC-SUA1500- [...] B00006BBK8
Get this one and be done with it.

'Pure' sine wave, almost 40 amps (this means "at-least" 1.5 hours of power for one pc), 950+ watts and easy maintenance.




Email APC for any further questions you have, your the costumer and it's your money.
GPU.

I need to back-up every kind of equipment. Wattage is not an issue but what I need is a prolonged running time on battery. And I have bad experience with stepped sine wave UPS. The PSU of my computer started buzzing every time it was on battery in such a way I was feeling it's going to explode. It was like very high voltage wires.

As I found the PSU manufacturer doesnt recommend using stepped sine wave but I had the same problem with monitor and other equipments (albeit they weren't buzzing that loud). So it's more UPS than PSU issue.

What?

No, I don't know that. As far as I remember physics the power is generated by a magnetic rotor inside a magnetic stator (sorry for bad translation) - what should generate pure sine wave.

what? can you elaborate or post a link to some articles that address this issue? Does it mean that every UPS I eventually buy will stress the connected equipments when running on battery?

I do. As I just wrote one post above I need prolonged time running on battery without overly stressing the connected equipments...

I did (actually the same time as I was setting up this thread). But I need some independent opinions because the sellers will never tell you everything (even if they are ultra-fair to their customers they still have an insider view which causes distorted perception).

That's why I need some independent opinions and I thank to everyone who gives me some!

I took a look at the output of my APC sine-wave UPS and it is noticeably cleaner than the mains itself; so purity may no longer be an issue (The various local loads distort the mains).