Research on Short-Circuit Withstand Capability of Transformer Considering the Mechanical Accumulation Characteristics of Insulation Materials

Aiming at the cumulative effect of the insulation pad inside the transformer coil and the paper-wrapped insulation outside the winding wire, a mechanical property accumulation characteristic test was conducted on the insulation paperboard for the coil and the paper-wrapped insulation for the wire, and the accumulation characteristic curve of the deformation of the insulation material under multiple impact tests was obtained. Based on the parameters of a 110 kV power transformer coil, a study on the verification and evaluation method for the short-circuit resistance of power transformer coils taking into account the cumulative mechanical properties of the insulating materials was conducted. Research has shown that under axial compression, the cumulative properties of insulating materials, whether insulating pads or paper-covered insulation for conductors, have a significant impact on the level of short-circuit forces that the transformer coils withstand. After repeated short-circuit shocks, the short-circuit forces experienced by the coils increase significantly, reducing the safety margin of the transformer. Therefore, timely verification of the short-circuit withstand capability of power transformers that have been subjected to short-circuit current shocks can help identify hidden dangers in advance and improve the safe and stable operation of the transformer.