For log Electrical Engineers were satisfied with 1 second event recording systems. For precision applications this is not sufficient. For power systems where reliability is critical, such as electric utility grid, data centres, hospitals, refineries, etc. GPS precision time synchronization in Power systems are required. "Sequence of Events Recording" SER based on GPS time synchronization techniques are employed here. With GPS "Sequence of Events Recording" engineers are synchronising the important grid data and events to 1 ms accuracy.