The analysis and processing of the overcurrent protection faults in IGBT (a common switch in CINRAD/SA radar transmitters), are described. As the fault alarm has no sign in the CINRAD/SA radar transmitter alarm panel, the troubleshooting is difficult. The overcurrent of the switch IGBT is monitored by its chip EXB841, and the overcurrent protection is conducted according to the over current signal outputs to cut off the drive signal outputs timely. Through the analysis of the flow condition monitored by EXB841 and alarms when faults occur, it is found that charging circuit faults of CINRAD/SA radar transmitter are the main cause of the IGBT overcurrent protection. The charging circuit faults result in the sudden current change of primary transformers and IGBTs,leading to the L〖SX(〗di〖〗dt〖SX)〗 changes in inductive voltage at both ends, the reverse electric potential difference between the IGBT C and E, the fast turnon diode cutoff, the overcurrent in EXB841 monitoring, and the quick cutoff of IGBT, as well as IGBT of the protection switch component.