Divide 3000VA by your line voltage to get the required amps. Here in the States, I'd need a 30A circuit at 120V and would absolutely have to run a new line from my breaker panel.
homelab
I have 220~240v, so that means I need > 14A then
Edit: hang on - that's only true if the UPS recharges in exactly 1 hour. If it charges over two hours it needs less power
But it can draw more current than the line is rated for. Everything electrical is about "can", not "will".
Yep, I have a 3000va unit in my main basement rack. I had to run a 30A circuit for it.
why not build your own much more flexible. shouldn't be very hard. just get a battery like this one https://www.amazon.com/Redodo-LiFePO4-Lithium-Lifetime-Off-Grid/dp/B094NN5KWY and an inverter.
i have had terrible experiences with these all in one UPSs that you mentioned, battery degrades fast and starts lasting only a fraction of the time. i would suggest getting a killawatt to measure power consumption, gives you a much better idea of what capacity inverter you need.
also not how the "1600VA" one is really only 960W https://powershield.com.au/wp-content/uploads/brochures/DefenderUPS_Range_Overview.pdf
You can see the capacity too its very tiny 12V / 9AH (x2) which is mere 216 watts!
I'm looking for something that is rack mountable and 2U in height. While it is possible to find off the shelf gear you can build your own out of, it isn't cheap.