In case your voltage amounts are unstable (ie: power stays on, but the actual voltage stage varies a good deal in the 220V standard), then I feel that's the kind of situation exactly where an AVR is helpful. For giant power units, dynamic uninterruptible power supplies (DUPS) are occasionally utilised. https://shanersldt.mdkblog.com/39664353/5-simple-techniques-for-uninterruptible-power-supply-adalah