Causes of Power Failure: Grid incomer relay intercepts blackout in synchronized power generating stations. It isolates faulty grid & safely islands the power plant with home load. It's catastrophic if power goes out that fails completely. Grid incomer relay prevents such an emergency in the event of grid failure. It lightens the severity of the power outage and mitigates a possible blackout condition with complete power failure into a brownout state with partial power outage. The major cause for grid failures are storm, rain and thunderstorm.