In this paper a model has been proposed to investigate the effect of Standard Lightning Impulses at voltages below the Basic Insulation Level (BIL) on winding geometry, based on the extraction of resistances, inductances, capacitances and conductance using Finite Element Method (FEM) and the resultant structural movement. The winding and insulation in a transformer can be subjected to overvoltage surges i.e. lightning strikes and switching events. If the frequency component of the incoming transient surges matches the resonance frequency zone of the transformer windings, the amplification and attenuation of the overvoltages along the windings may result in abnormal voltage stress on the conductors of the winding. Hence, the monitoring of electromagnetic forces and the resultant mechanical stresses are of paramount importance in the minimization of the occurrence of mechanical failure in transformers. The Standard Lightning Impulse (SLI) was induced at the outermost layer of the High Voltage (HV) winding of the 11/0.415 kV transformer and resultant electromagnetic forces acting in axial and radial directions were computed. The computed directional forces were in turn induced to the winding structure to observe the structural behavior. The FEM model was tested using an SLI with a voltage, 35 kV, below the BIL of this class of transformer. The modeling showed that the axial and radial forces impinge a mechanical stress in the outer column supports of the winding structure. This model will allow the investigation of buckling within windings at elevated voltages above the BIL.

在本文中，基于使用有限元方法 (FEM) 和电导提取电阻、电感、电容和电导，提出了一个模型来研究电压低于基本绝缘水平 (BIL) 的标准雷电脉冲对绕组几何形状的影响。由此产生的结构运动。变压器中的绕组和绝缘体可能会受到过电压浪涌的影响，即雷击和开关事件。如果传入的瞬态浪涌频率分量与变压器绕组的谐振频率区相匹配，则过电压沿绕组的放大和衰减可能会导致绕组导体上出现异常电压应力。因此，监测电磁力和由此产生的机械应力对于尽量减少变压器机械故障的发生至关重要。标准闪电脉冲 (SLI) 在 11/0.415 kV 变压器的高压 (HV) 绕组的最外层感应，并计算出作用在轴向和径向方向上的电磁力。计算出的方向力又被引入绕组结构以观察结构行为。FEM 模型使用 SLI 进行测试，其电压为 35 kV，低于此类变压器的 BIL。建模表明，轴向和径向力会在绕组结构的外柱支撑中产生机械应力。