Analysis of Sudden Pressure Relay Operation Causes and Preventive Measures for 500kV Main Transformer No-Load Closing

Based on a case involving the operation of a sudden pressure relay during the no-load closing of a 500kV transformer, an investigation was conducted by examining the on-site equipment and analyzing the fault recording waveform at the moment of closing. The root cause was identified: the operation of the sudden pressure relay was triggered by vibrations and oil flow surges generated by the inrush current. Specific preventive measures were proposed accordingly.