Is a true sine wave UPS necessary?

A

Atif

Gawd
Joined
Aug 26, 2004
Messages
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I'm in the market for a UPS to go with this PC that I put together for my sister about two months ago:


https://leenabutt.com/halal-recipes/leens-mean-dream-machine


We don't live in a rural area or have infrastructure issues that result in frequent brownouts, but we figured better safe than sorry.


In using the eXtreme Outer Vision PSU calculator, at 100% utilization, it indicated we should expect a 505W load.


With that said, I was seriously tempted by this deal, however I was scared off when I saw some comments that modern power supplies with PFC may require a true sine wave output:


https://slickdeals.net/f/13277716-apc-900va-ups-back-ups-w-9-outlets-6-ups-all-9-surge-bn900m-59-99


First, would the above UPS be adequate for this particular PC? Second, if not, would this guy be:


https://www.cyberpowersystems.com/product/ups/cp1000pfclcd/


Thank you all for your time and expertise!
 
Pure sine is nice.

I've never seen a computer fry for not having it though.

Either of those units is more than enough so long as you aren't expecting it to run for more than 10 minutes or so
 
120V AC from the wall outlet is measured as an average voltage (+/-). In reality the peak of the sin wave is around 170V.

A true sin wave UPS will reproduce this, a more basic UPS produces a square wave of a lower voltage, both the square wave and the sin wave will "average" to (+/-)120V, and power supplied will handle this generally.

But, they are designed with a sin wave in mind. The square wave may cause coil whine to be worse, is hard on the filtering capacitors, and may cause some wobble of the output voltages of the power supply, higher quality PSU's may have more built up filtering or control circuitry that detects and handles this properly, but dont count on it.
 
More important the true sine wave for PC use is one that is compatible with Active Power Factor Correcting power supplies. Back when PFC was a new thing, a lot of APC UPSs either would shut down or cause the PFC PS to shut down when the UPS went on battery. Of course APC blamed the PS makers and the PS makers blamed APC. The solution at the time was to get a sine wave UPS.

I think since then that both UPS and PS makers have mostly fixed the problem but it still pops up on occasion.

BTW - it is also useful to put the modem, router and any switches on a UPS as well. Cuts down on connection blinks as a lot of the wall warts go cheap on filter caps.
 
Many UPS manufacturers have a "simulated sine wave" as well now. Different manufacturers often call it something different. Basically it means the UPS produces square waves, but they vary the voltage into a higher and lower voltage output in a wave pattern to halfway sorta kinda simulate a sine wave.
Just be aware because I have seen some models claim "sine output" when in reality it is this simulated sine wave and not a real, smooth one
 
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