Automatic disconnects the power when it is bad and reconnects after 90 seconds when it is good.eliminates the need to switch off appliances when the electricity fails.these specifcations for a standard 220/240v unit, other specifications are available refer to you manual for details. specifcations 13amps over- voltage,surges & spikes power-back surges normal:220/240v delay time:10 secs disconect voltage:165v/255v .high voltage screenshot shows:hi low voltage screenshot shows:lo deelay time screenshot shows: