A circuit model of transformer short-circuit faults is established to study magnetic-structural force coupling characteristics of windings in distribution transformers under different short-circuit conditions

the current calculation results under different short-circuit conditions are obtained

and the current of the model calculation results are consistent with theoretical formula derivations. Based on the finite element simulation software

the current is imported as the winding excitation into the three-dimensional simulation model of the oil-immersed transformer. The results indicate that the magnetic flux density distribution in the transformer windings follows a pattern of being higher in the middle and lower at both ends. The winding stress distribution aligns with that of the magnetic flux density. The maximum magnetic flux density and stress occur during a three-phase short-circuit. Experimental measurements validate the accuracy of the simulation method. Based on the results above

the influence of cumulative effects on the deformation characteristics of transformer windings is considered. The deformation characteristics of windings under both single and multiple short-circuit force impacts are analyzed. The results indicate that the deformation is most significant when the winding experiences a three-phase short-circuit force impact. Under a single short-circuit force impact

the maximum deformation and maximum residual deformation of the winding are 602.0 µm and 52.8 µm

respectively. The maximum deformation and maximum residual deformation of the winding stabilize after the fourth short-circuit force impact

with stable values of 312.0 µm and 61.9 µm. The research findings provide a theoretical basis for considering the deformation characteristics of distribution transformers under cumulative effects and for enhancing their short-circuit withstand capability.