Outlet short circuit on the low-voltage (LV) side and winding inter-turn short circuit faults are hazardous to transformer operation. To investigate the formation mechanism of winding insulation faults of distribution transformer, ANSYS Maxwell was used to build a coupled magnetic field-circuit model with the same structural dimension as the actual distribution transformer. An outlet short circuit and winding inter-turn insulation faults were set by using the voltage-controlled switch in the external circuit of the model. Subsequently, the differences in the electromagnetic characteristics and the electrodynamic force distributions of the windings under three operating conditions, namely, nominal load, three-phase outlet short circuit on the LV side and inter-turn insulation failure were studied, respectively. The results show that compared with the rated load, in the cases of outlet short circuit and inter-turn insulation faults, the amplitude of winding current increases by 20 and 50 times, the magnetic field strength grows by 20 and 17 times, and the electrodynamic force rises by 400 and 230 times, respectively. Outlet short circuit fault is more likely to cause the winding instability and deformation, and inter-turn short circuit fault can easily burn out winding insulation. Therefore, corresponding preventive measures were proposed.

中文翻译：

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配电变压器出线短路与绕组绝缘故障特征对比分析及预防措施

低压侧出线短路和绕组匝间短路故障对变压器运行存在危险。为了研究配电变压器绕组绝缘故障的形成机理，采用ANSYS Maxwell建立了与实际配电变压器结构尺寸相同的磁场-电路耦合模型。利用模型外电路的压控开关对出线短路和绕组匝间绝缘故障进行设置。随后，分别研究了额定负载、低压侧三相出线短路和匝间绝缘失效三种工况下绕组电磁特性和电动力分布的差异。结果表明，与额定负载相比，在出线短路和匝间绝缘故障情况下，绕组电流幅值分别增大20倍和50倍，磁场强度分别增大20倍和17倍，电动力力量分别增加了400倍和230倍。出线短路故障更容易造成绕组不稳定和变形，匝间短路故障很容易烧坏绕组绝缘。因此，提出了相应的预防措施。