Fault Mechanism Analysis of Voltage Transformer Caused By Iron Core Saturation

Voltage transformer, providing primary system voltage information to secondary system to measure, monitor and protect the power grid, is a very important equipment to ensure the safe operation of power grid. In the neutral ungrounded distribution system, since the excitation inductance of electromagnetic voltage transformer has nonlinear characteristics, and the ferromagnetic resonance phenomenon are prone to occur under certainconditions, which has serious influence on safe and stable operation of the system. The ferromagnetic principle of electromagnetic voltage transformer in neutral ungrounded system and its harm are briefly analyzed and introduced. Combined with the actual case, the damage reason of 10kV bus voltage transformer in substation is analyzed and the correctness of the analysis result is verified by theoretical calculation. Finally, the countermeasures are put forward to improve the operation safety of voltage transformer in distribution network.