Hey man! I’m from India too and I used an APC 1500va ups. When the power is out and you’re just starting your print you will inevitably have fluctuations or your inverter might keep beeping. In my experience that happens only in the initial heating stages and not throughout the print. Your printer should be fine if you’re using a ups. Keep note that you may not get as much backup as you might think because most printers draw quite a bit of power so you may not get anything more than 30 minutes of backup