Analysis of First-Layer Failure and Weak Points in Transformer Windings Considering Cumulative Effects of Curved Copper Mechanical Properties

The cumulative deformation behavior and sudden mechanical damage of transformer windings under multiple short-circuit impacts are critical issues affecting equipment safety. To address this, this paper proposes a transformer model incorporating the mechanical properties of spacers and curved copper in a split-disk winding structure, systematically investigating the deformation evolution under short-circuit impacts. First, stress-strain curves of curved copper material under different loading modes were obtained through radial bending tests. Subsequently, combining three-dimensional finite element simulation of layered disk windings, the cumulative deformation patterns of windings under multiple short-circuit impacts were analyzed, identifying the primary failure risk zone (the first-layer failure location) and pinpointing failure weak points. Finally, a concurrent failure mechanism between winding and spacer deformations was revealed by comparing the cumulative deformation development between windings and spacers. Results indicate that significant plastic deformation initially occurs in the middle layer of the medium-voltage winding, constituting the first-layer failure zone, with the edge region of the winding-spacer contact surface confirmed as the failure weak point. The established model can accurately predict winding deformation progression, providing theoretical support for anti-short-circuit design and structural optimization of transformers.