Abstract: This article takes an explosion event of a damping resistor in a 500kV series compensation station as a "test mouse", uses relay protection action reports and fault recording as detection points, and uses various clues left after the explosion of on-site equipment to peel off the cocoon. Through comparison and verification before and after, the accident scene is finally restored, the root cause of the accident is identified, and attention points for operation, maintenance, and maintenance tests are proposed, To prevent the occurrence of such accidents from the root cause. At the same time, it also showcases textbook style cases for readers on how to use fault recording graphics to deeply analyze the nature of faults.