Analysis of 35 kV Main Transformer Differential Protection Trip
This paper introduces an incident of a 35 kV main transformer differential protection action trip,and through the method of systematically examining and analyzing each device in the fault bay,as well as analyzing the material quality and installation techniques of key components,combined with the elimination method,on-site relevant data,and software simulation analysis,it is determined that the primary cause for the trip of circuit breaker 301 was the presence of sharp burrs at the end of the moving contact screw of the disconnector.During operation,these sharp burrs generated a floating potential,and when there were fluctuations in system voltage or increased humidity,discharge occurred due to the sharp burrs causing an instantaneous short circuit between phases B and C,ultimately triggering the main transformer differential instantaneous and ratio differential protections.The entire process of the discharge fault has been analyzed,and corresponding preventive measures have been proposed.This case study of a 35 kV main transformer differential protection action trip provides experience and reference for the prevention and handling of similar incidents in the future.