UPS advice - stepped sine wave or pure?

[tgfyhre]

My APC battery backup UPS needs a new battery, and I'm considering getting a new unit, as mine is approaching 5 years old. I've been reading that standard UPS devices put out a stepped sine wave that can cause issues and possible damage or reduced lifespan with newer Active PFC Power Supplies and LCD monitors. Cyberpower make some that output a "pure sine wave" that is supposed to be better for PFC hardware. Is this really an issue I should be concerned with?

There are 2 UPS units from Cyberpower I'm looking at - 1 has 12 outlets which gives me 2 more than I currently have, which I could definitely use. But it only puts out a standard stepped sine wave. Then there's a similar one with only 10 outlets that outputs a "pure sine wave". Is it worth getting the pure version and losing 2 outlets, or is it not as important as some are saying? I want to do what's best for my equipment of course, especially because I tend to get random power outages for anywhere from a few seconds to a few minutes fairly often - enough to warrant owning one of these units.

 

[logicearth]

You really don't need to pay that kind of money. A "pure" sine wave is no better or worse then a stepped sine wave. Not to a properly designed power supply. A properly made power supply filters the incoming power and filters the out going power. In either case the power from an APC is cleaner then what is coming from the Mains directly.

So here is my advice. Forget the sine wave nonsense and get what you can afford that gives you the backup time you need.

 

[tgfyhre]

Thank you. I didn't know what to think after reading some of the information out there about the PFC power supplies not liking the stepped UPS units. Your advice goes against some of what I've read that state there is indeed a difference that can affect PFC power supplies.

I have read several comments and sites that talk about the buzzing from a power supply when a stepped UPS is used. I do notice that when my older APC UPS kicks in, instantly I get a loud click followed by a buzzing sound. Comments seem to say that the buzzing sound is the power supply and is a result of a PFC power supply not liking the stepped power from the UPS.

I'd love to avoid the extra cost and gain extra outlets on top of the savings - I just want to make sure that I don't regret it later. Why do some sites state that it's so important to go with a pure sine wave?

Even APC's site seems to suggest that their units aren't intended for active PFC power supplies. And there are reviews that state their PFC power supplies don't work at all well with stepped UPS units. Very confusing.


This was found on another forum, where the poster spoke with APC regarding this issue:

"I just spoke with both Silverstone and APC. Silverstone is going to get back to me on this question, but APC was pretty clear -- they strongly felt that PFC power supplies should use true sine wave UPSs. They told me that the reason for this was because PFC power supplies require a much faster changeover time when the battery kicks in, and that due to the design of stepped sine wave UPSs, they were not always fast enough to satisfy the power supply. This could lead to the PSU shutting down when the battery tried to kick in. The guy I spoke with said that the stepped sine wave wouldn't "damage" the PSU, but that it simply might not work, and that if it DID work, it might not "always" work. Apparently it depends on the specific power supply."

 

[Lady Fitzgerald]

You really don't need to pay that kind of money. A "pure" sine wave is no better or worse then a stepped sine wave. Not to a properly designed power supply. A properly made power supply filters the incoming power and filters the out going power. In either case the power from an APC is cleaner then what is coming from the Mains directly.

So here is my advice. Forget the sine wave nonsense and get what you can afford that gives you the backup time you need.

Bad advice. The older PSUs could operate OK on a stepped sine wave but many of the newer PSUs, and some peripherals, need pure sine wave power to function properly. Many PSU vendors, such as Corsair, recommend using only pure sine wave to power their PSUs. Pure sine wave doesn't cost all that much more and future proofs you for later components that may be more particular.

As far as number of outlets goes, if the UPS can handle the load, you can always use a power strip or multi-outlet extension cord plugged into the UPS. I did that with my UPS; I have my three monitors plugged into a three outlet tap that connects to one of the UPS outlets via a short extension cord. My UPS can easily handle the load even though I ran out of outlets on the UPS (part of that was due to a wall wart PSU for my HDMI splitter). Right now, I'm using only 270 watts and the UPS is rated for 1500 watts (I have 99 minutes runtime available on batteries right now and I've never gone over 375 watts consumption so far).

 

[tgfyhre]

And this is why I'm confused. I hear two different stories.
Here's what Silverstone had to say in regards to this issue, as posted by the same person I quoted above:


"Okay -- here is a follow-up response from the Silverstone engineer in Taiwan (with good news for those of us in the US.)

"It is fine if you living in US and used 120V input in your OP700, even by a not pure sineware UPS."

This is of course good news for those of us in the US. This is direct confirmation from Silverstone that if you're in a country that uses a 120V standard, you CAN use non sine wave UPSs without damaging their power supplies."

Here's a link to the thread:

Active PFC Power Supply and NON true sine wave UPS. - Page 5 - jonnyGURU Forums

Of course that's an older thread, so I don't know how much has changed.

 

[Lady Fitzgerald]

That article is seven years old. More PSUs are PFC now and more of them are intolerant of stepped sine wave. Why spend the money on a stepped sine wave UPS only to discover your PSU won't work with it?

 

[tgfyhre]

Well, I agree - that's why I created this thread. I want to make sure I get the right UPS to handle newer power supplies, monitors, etc.

All I know is my current PSU buzzes very loudly when my APC UPS kicks in, and that UPS is a stepped sine wave.

So why does the industry make and sell stepped UPSs that are clearly marketed for household PC use when they are a poor idea to use with modern power supplies? This is baffling to me. I never would have even known about any of this and just bought another stepped sine wave model if I hadn't just stumbled onto a comment about this issue.

That thread is old but it's 15 pages and more recent posts are from last year.

 

[tgfyhre]

Here are a couple video reviews on youtube that talk specifically about this issue and the Cyberpower UPSs:

https://www.youtube.com/watch?v=DoIW0Jh-K0A
:40 he starts talking about sine wavs with this UPS

https://www.youtube.com/watch?v=ViGZ7hyAyBk&list=FLypBqYSz9t64AcEVu54-9Ww&index=4
3:40 he starts discussing the same issue

Either they're both wrong, or it's pretty important to get one with with a pure sine wave.

 

[Lady Fitzgerald]

The fact that your PSU buzzes when running off stepped sine wave is plenty reason to go with a pure sine wave UPS.

As to why manufacturers still sell stepped sine wave UPSes? There are some to many PSUs that can run on them. Also, PSUs aren't the only thing people use with a UPS. Many of other things people put on a UPS can run fine on Stepped sine wave.

I wouldn't take too much stock in what Johnny Guru has to say. He is supposed to be a PSU expert but I have seen him give some questionable advice fairly recently, particularly on UPSes.

 

[Lady Fitzgerald]

Here are a couple video reviews on youtube that talk specifically about this issue and the Cyberpower UPSs:

https://www.youtube.com/watch?v=DoIW0Jh-K0A
:40 he starts talking about sine wavs with this UPS

https://www.youtube.com/watch?v=ViGZ7hyAyBk&list=FLypBqYSz9t64AcEVu54-9Ww&index=4
3:40 he starts discussing the same issue

Either they're both wrong, or it's pretty important to get one with with a pure sine wave.

I just watched parts of both. Both were dead on with why PSUs should use pure sine wave power but, curiously enough, both gave a somewhat inaccurate description of what a stepped sine wave (also known as a modified sine wave) looks like. Both described a square wave. Stepped sine wave uses groups of square waves but varies the voltage of each square wave so each group approximates the curve of a sine wave. Btw, I've watched a lot of videos from Linus and this is only the second and third time I've seen him get some detail detail (he also missed defining the voltage of a sine wave in the video but also had some text appear that corrected it).

But I'm into nitpicking now. For the big picture, both gave excellent advice.

 

[tgfyhre]

Here's a review I found on the Cyberpower UPS I'm considering:

CyberPower CP1500PFCLCD - Enthusiast Power Protection: Four-Way 900 W UPS Roundup

Interestingly, this model line by Cyberpower doesn't actually output a pure sine wave, but rather an approximation using what it terms "adaptive sine wave":

"Besides being the smallest, lightest, and cheapest unit in today’s roundup, the CP1500PFCLCD is also the only unit that has not fully replaced step-wave with pure-sine-wave circuitry, instead opting for a modified triangular wave that CyberPower calls “Adaptive Sinewave” to eliminate the zero power state that has so often prevented step-wave units from working with active PFC power supplies. This basically means that users get the enhanced compatibility of a sine wave unit at a low price similar to many step wave competitors."

From what I've read it outputs a wave so close to pure that PFC power supplies accept it as pure.

 

[Lady Fitzgerald]

I wouldn't trust it myself for PFC PSU. Consider how much your computer cost
and how valuable your work on it is versus what you are willing to pay for a
UPS.

Keep in mind that a UPS is a long term investment. Batteries can last as long
as three years, sometimes more, and are usually replaceable for much less than
replacing the UPS.


Edit: The Tom's Hardware article is about two years old and may either be reviewing an earlier version of that UPS or they just might be full of it. I just looked that model number up on Amazon's, Newegg's, and CyberPower's websites and all three said that it is a pure sinewave unit that is 100% PFC compatible. If this is the unit you can afford, then it should be ok. I would still suggest getting it locally if possible since I saw some complaints on damage on arrival due to packing issues.

 

[tgfyhre]

The problem is there's no way I can afford an APC full true sine wave unit. It's just beyond my spending range. The Cyberpower seems to offer something that comes much closer to the pure sine wav output PFC power supplies require.

The question is - would this unit offer an improvement and a benefit over a standard Cyberpower or APC UPS with standard stepped sine wav output, or would there be no benefit? From reviews on this unit it seems there is a benefit over the cheaper alternatives like the one I own currently.

If money wasn't an object, of course I'd go with a true pure sine output, but this costs far less and it puts it in a range I can afford, with hopefully some gain over the standard units in this price range.

 

[Lady Fitzgerald]

See the edit in my previous post.

 

[tgfyhre]

That item on Amazon says the following under Product Description:

"Cyberpower PFC Adaptive Sinewave Intelligent LCD CP1500PFCLCD 1500VA UPS CP1500PFCLCD Uninterruptible Power Supplies (UPS)"

Adaptive Sinewave is what I described above - not pure sine wave, but simulated. Also, here's an answer in one of the first questions somebody asked about the adaptive sine wave technology on that amazon page:

"Senior Technical Support Specialist at CyberPower:
"No digitally created wave can be a true mathematically curved analog wave. But the number of digital steps used to create the wave can be great enough that the electronics used in even the highest efficiency computer power supplies are unable to distinguish them from an analog wave. The total harmonic distortion of the output on battery is under 2% which means the output of the UPS is closer to a mathematically ideal analog wave than the powercoming out most peoples walls.
"These units were created specifically for the needs of computer users with Active PFC power supplies. We put PFC in the model name to highlight the fact that these units are compatible with Active PFC Power Supplies."

 

[Lady Fitzgerald]

The only description I found on Amazon was it was pure sine wave. In that same question, this is a response:

"Adaptive sine wave was an early marketing term that was used for this series of UPS system. Our marketing has since changed to reflect the true wave form output of this series of CyberPower UPS systems."

It could be you are reading an older description of the UPS instead of the current one.

It doesn't really matter how a sine wave is achieved as long as it results in an actual sine wave. If enough steps with little or no space between the steps are used to simulate the sine wave (which most stepped sine wave supplies do not have) and is then filtered to smooth out the tiny steps, the result will be essentially the same as the sine wave the power companies put out, possibly with less distortion. I still feel this UPS will be fine. If it wasn't able to handle PFC PSUs, it wouldn't get as high of a user review rating as it does.

 

[tgfyhre]

Thank you for digging deeper into this. Would you mind linking to the Amazon page with the item that carried that description? I want to make sure I purchase the right version of that unit.

Is this the item?

Amazon.com: CyberPower CP1500PFCLCD PFC Sinewave UPS 1500VA 900W PFC Compatible Mini-Tower: Electronics

 

[Lady Fitzgerald]

That is the one. I also noticed this note: Item is hazmat and non-returnable. I suggest trying to buy it locally if possible to simplify returning it if it should arrive DOA (unlikely but still possible).

 

[tgfyhre]

Wow, I can't believe they wouldn't allow a return on this, even if it was dead. How is that even legal?

Nobody locally sells any of these. I checked Newegg and this item is covered under their standard return policy. I guess Amazon loses this one.

 

[Lady Fitzgerald]

Wow, I can't believe they wouldn't allow a return on this, even if it was dead. How is that even legal?

Nobody locally sells any of these. I checked Newegg and this item is covered under their standard return policy. I guess Amazon loses this one.

I'm guessing if you had to return it due to it being DOA, you would have to deal directly with CyberPower instead of Amazon

Any vendor can legally refuse to accept returns on anything as long as that is made clear up front. In this case, Amazon apparently doesn't want to deal with the legal hassles of dealing with hazmat returns that may become hazwaste. I used to deal with hazwaste when I was working for the utility I now get my pension from. You would not believe the huge number of complicated regulations and incredibly high penalties involved with hazwaste.

Although I don't blame Amazon for not wanting to deal with potential hazmat/hazwaste issues, I would do the same as you and go with Newegg.