In case your voltage levels are unstable (ie: power stays on, but the actual voltage amount varies a good deal through the 220V common), then I think that's the type of situation where an AVR is helpful. Could it be true that surge protectors hinder general performance ? I understand https://preecha-concrete-pile27047.daneblogger.com/32899012/new-step-by-step-map-for-uninterruptible-power-supply-ups