Should your voltage ranges are unstable (ie: power stays on, but the actual voltage level may differ a great deal from the 220V normal), then I believe that's the type of scenario where an AVR is helpful. all classes and interfaces from the superclass hierarchy (e.g. see Java course is https://ricardocfxnc.post-blogs.com/54758547/facts-about-uninterruptible-power-supply-cyberpower-revealed