If your voltage amounts are unstable (ie: power stays on, but the actual voltage amount may differ a lot from the 220V regular), then I think that's the sort of state of affairs in which an AVR is helpful. Your browser isn’t supported any longer. Update it to have the https://shaneigebw.blogunteer.com/32800869/the-fact-about-ups-uninterruptible-power-supply-that-no-one-is-suggesting