Abstract：Incidents such as the burning of electromagnetic voltage transformers（PT），damage to primary

harmonic suppressors，and fuse tripping occur frequently in low and medium voltage distribution systems due to

ferroresonance，severely affecting the safe and stable operation of the system. Therefore，through theoretical

analysis and combined with field case studies，it was verified that the saturation current produced by PT saturation

due to electromagnetic transient impacts from system single-phase ground faults and circuit breaker operations was

the main reason for the frequent fuse tripping. Secondly，the factors influencing the saturation current of PT was

analyzed and the capacity of fuses to withstand the PT saturation current was tested. The research indicates that the

probability of fuse tripping could be reduced by increasing the PT's DC resistance，choosing cylindrical harmonic

suppressors with relatively high knee-point voltages of their volt-ampere characteristics，and increasing the rated

current of the fuses. Finally，specific recommendations for the selection of PTs，harmonic suppressors，and fuses

were provided，offering reference measures for resolving the issue of frequent fuse tripping in electromagnetic

voltage transformers protected by fuses.

      Key words：electromagnetic voltage transformers；fuses；frequent tripping