Research on the Fault Diagnosis of Pre-insertion Resistor of AC Filter Circuit Breakers

The pre-insertion resistor is used to suppress closing inrush current and overvoltage. However, it is not uncommon for the pre-insertion resistor to explode or break down in the application of filter circuit breakers. This paper studied the fault diagnosis technology of the pre-insertion resistor of AC filter circuit breakers. The fault types of the pre-insertion resistor are divided into three categories according to the engineering practice, including short circuit, breakdown and open circuit. Then the simulation analysis with different faults was carried out respectively, and the corresponding transient current characteristics were obtained. The study found that when the pre-insertion resistor is faulty, parameters including the harmonic content in the closing inrush current, the appearance time of the inrush current peak and the inconsistency of three phases are obviously different from those in the normal condition, which can be used into the fault diagnosis technology of the pre-insertion resistor.