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How to buy an appropriate Back Up Power Supply for short power break?

This is the power supply I'm using. EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply

In term of compatibility, price what are the requiered spec to look for?

Mark
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  • Would you like to know what kind of UPS you have to buy ? – maudam Sep 30 '16 at 18:10
  • Yes, but for the sake of knowledge explain a little bit why you suggest a particular kind – Mark Sep 30 '16 at 18:14
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    You can't go wrong with an APC UPS unit. They will support any large capacity Power Supply. 1000VA Power Supply should be no problem supporting that PSU. – t a b designworks Sep 30 '16 at 18:19
  • The amount of VA of the Back Up Powersupply influence directly the price. How can I mesure what is the threshold of what I need. – Mark Sep 30 '16 at 18:26
  • https://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=measure+watt – maudam Sep 30 '16 at 18:30
  • "How can I mesure what is the threshold of what I need" -- Use a power meter, such as a KIll-a-Watt. Measure your PC with a monitor, unless you know how to enter commands blindly. And never test a UPS by unplugging it from the wall outlet. Use a switched power strip to ensure earth grounding. – sawdust Sep 30 '16 at 19:18

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You should use a double conversion (not line interactive) because you have an active power supply. Ups power is expressed in VA where 1 Watt = 0,7 VA (0,9 in very good UPS) Given that a computer use rarely the full power of his supply you need at least a 600 VA UPS but a 1000VA is just a little expensive. Normally time on batteries depends on UPS power because a 1000VA UPS have a battery larger than 600VA. Normally a standard 1000VA UPS have a battery lasting 10 minutes or so. Buy a Good quality UPS and not a cheap one. The difference is real. Never attach a printer to the UPS. For equipments like printers, usually UPS have additional ports (not backed up by batteries) for overcurrent protection.

maudam
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  • "1 Watt = 0,7 VA (0,9 in very good UPS)" -- That's not true. The conversion from VA to watts uses the power factor, which depends on the electrical load, not the UPS itself. See http://superuser.com/questions/348103/pc-watts-usage-comparison/348104#348104 – sawdust Sep 30 '16 at 19:11
  • By load and by some techniques used in top-level UPS as this one (for small ups http://ups.legrand.com/media/document/UPS-LGR-0046-GB.pdf With big UPS > 5000VA the VA/W can be 0,9 – maudam Sep 30 '16 at 19:35
  • The UPS VA to Watt conversion is more truth in advertising than electrical theory. Computers are close to a resistive load, so expressing VA at all is hype, unless you're using the UPS to run a motor or something. The UPS manufacturers do that as a way of making their specs look better. VA is a bogus number that they can wildly inflate by using an irrelevant power factor. Watts is all that counts. 2) Your VA vs. runtime explanation is inaccurate. This rating just defines the load that won't trip the internal breaker. (cont'd)
    • – fixer1234 Oct 01 '16 at 01:26
  • I've seen cheap UPSs with a high VA rating only because the components could carry the current. But using them at that load would barely give you time to shut down. There is no direct relationship with run time. However, if you get a unit designed to power a 700W load long enough to shut down, and your load is only half that, you will get more run time out of the battery. The battery's amp-hour rating is what determines run time. Getting a unit with a high power rating doesn't guarantee you anything about runtime. – fixer1234 Oct 01 '16 at 01:26