If the voltage ranges are unstable (ie: power stays on, but the actual voltage stage differs lots in the 220V common), then I think that's the type of situation the place an AVR is useful. In case you have a big Office environment with several devices, then the Eaton Eaton https://bydauto306273.blogdal.com/34278123/a-review-of-uninterruptible-power-supply-cyberpower