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Pure Sinewave UPS for Active PFC Power Supplies!

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a b ) Power supply
July 12, 2012 3:44:40 AM

Hi,
I cannot find an answer anywhere on google.

A lot of people recommend using a pure sinewave UPS for all active PFC power supplies for a variety of reasons. I have some very specific questions though that maybe some people can answer.

1) Suppose I am using a modified sinewave UPS...just as a situation. Is it providing a modified sinewave ALL the time or JUST when it is using the battery?

2) Can a modified sinewave UPS DAMAGE a PSU even if everything works fine at first? Reason I am asking is because PSU's rectify the AC right into DC as soon as it gets it before doing anything else, so why does the sinewave matter or is this more of an issue of whether it works or doesn't.

3) If a UPS is damaging a PFC PSU, does it only matter if its during battery operating or even during regular operation? Relates to question 1.

4) I am using a Cyber Power Systems CP1350AVR UPS with a Corsair AX650 PSU and I've used it for like 3+ years before with a Corsair TX850. Never had a single hitch or issue, the UPS worked exactly as it should during power outages and nothing happened. Is my PSU being silently degraded/damaged or is everything fine and I need not worry?

Thank you if anybody can offer any help with this.
a b ) Power supply
July 12, 2012 5:05:01 AM

You're fine. I have the same UPS and spent a quite a bit of time researching this before I bought it. In summary there is a lot of mythology around pure sine wave, but it is unnecessary for anything but extremely sensitive audio and scientific equipment. The best short answer I heard was something like "psus are designed to run off AC directly off the grid, by comparison to which any UPS puts out lovely clean sine waves".

Someone else may be able to provide more technical detail, but I don't believe my summary will be overturned: "Don't worry about it".
a b ) Power supply
July 12, 2012 6:11:47 AM

Doesn't a power grid run on alternators?
A real alternator like a turbine with a magnetic field would produce a real sine wave wouldn't it? Or does variations on load in the grid affect its quality due to the grids resiliency to respond?
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a b ) Power supply
July 12, 2012 11:48:09 AM

Hopefully somebody with a better electronics background will step in, but apparently the utility power has harmonics introduced both by their own PFCs and by feedback from things attached to it like arc welders.

Here's the thread upon which I based my choice of UPS:

http://www.jonnyguru.com/forums/showthread.php?t=3964&p...

Though the overall thread is far from clear, my read of the consensus is: people are using non-pure sine wave ups every day all over the world with all sorts of psus and not having a problem. At worst, the psu will be less efficient or even buzz when running off ups, but since you only do that for a maximum of a few minutes every day (and hopefully a lot less) it doesn't matter. People have had problems with a UPS simply not working with their psu, but this can be tested by simply pulling the plug and seeing if the computer stops.

a b ) Power supply
July 12, 2012 11:57:13 AM

I hope nobody buys a particular UPS based on my recommendation, 'cause I don't fully understand this issue...just explaining how I came to my decision.
a b ) Power supply
July 12, 2012 12:51:13 PM

I read that entire thread.
Some things said there make perfect sense...others do not.

From my understanding, these PSU's are universal for American and European power standards.

European power provides you with a lot more voltage from the grid, so from what I see, since it handles that full range, it has one large capacitor that handles all the voltages. Since the capacitor is designed for the European grids, the American grids should be handled by it a lot easier. The issue I heard of non-sinewave UPS's is really consistent too high of a voltage or overvoltage that can damage the capacitor, which may be a problem in Europe, but I cannot see it being a problem in the United States.

This hole thing has me really thinking though, a PSU rectifies current when it receives it using semi conductors that split it into terminals and it uses a capacitor to eliminate the modulation (crests/troughs) of the modulated DC electricity that is coming from the semi-conductor diodes. I do not see why simulated or modified or stepped sinewaves would matter at all in this situation for those components. Current rectifying is very cheap and easy, so I cannot imagine a PSU company making a crappy system to convert AC to DC by not using good enough components for it, because as I said its not difficult to do this. I think the entire reason for a PSU converting current to DC and then BACK to AC with its own inverter system is for this reason, at least even that makes some sort of sense.

I also saw that whenever the voltage changes steps in bumps, there is a short delay of no power...depending on the UPS's quality, that delay may be to long for some PSU's to sustain power, for others it may work. However it seems unlikely for an *online* ups.

There is no solid answer anywhere. I may have to do use an oscilloscope and do some of my own measurements/research. Either way, I'm not on a pure sinewave UPS and everything works perfectly fine...maybe for the reasons I described above, maybe not. I want to test the power quality of my personal electricity service and see how *pure* it is.

If anybody has any knowledge on this, please comment.
a b ) Power supply
July 12, 2012 3:25:19 PM

Thank You!
The first article was very interesting. I don't know how reliable or how correct that author is, but his mentality is similar to mine in the fact that a power supply rectifies current into DC no matter what so it really doesn't matter what kind of wave of AC it gets before hand. I think that as long as the capacitor is not overloaded due to the continuous maximum sustained voltage then it does not matter, the semi conductors split the current into terminals no matter what they get. I still may be wrong, and cannot find any OFFICIAL, confirm information...perhaps because companies don't want it to be available.
November 11, 2012 1:35:21 PM

blackhawk1928 said:
Doesn't a power grid run on alternators?
A real alternator like a turbine with a magnetic field would produce a real sine wave wouldn't it? Or does variations on load in the grid affect its quality due to the grids resiliency to respond?


All power is generated in AC form, but some times it is converted to DC to be transmitted very long distances; therefore, needs to be rectified and then converted back to AC.

http://en.wikipedia.org/wiki/High-voltage_direct_curren...

Mercury switches are the same as non pure sine wave power supplies.
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