Quite apart from the mains power supply interruption (power failure), there are voltage dips (power sags), pulse voltage (high voltage spikes), transient over-voltage (switching transients), voltage surges (power surges), noise interference (noise), frequency (frequency variation), voltage fluctuations and flicker (brownout) and other problems, which is causing the computer equipment or precision instruments crashes, damage to internal components and shorten the life of other hardware and software as well as loss of data loss.