The Vibration‐Induced Separation Phenomenon Between Winding Disks and Spacers in Transformer Windings Under External Short‐Circuit Conditions

ABSTRACT Under external short‐circuit conditions, transformer windings are subjected to axial vibrations induced by axial electromagnetic forces. Due to the unidirectional compressive nature of spacers, separation between winding disks and spacers may occur, threatening the axial mechanical stability of the windings. Extensive research has been conducted on axial vibration calculation models and the vibration characteristics. These efforts have led to the establishment of vibration models based on mass‐spring‐damper systems, and investigations into the effects of factors such as moisture, ageing and damping on the behaviour of spacers and the vibration process. However, neither the impact of disk–spacer separation on winding stability has been analysed, nor have the critical conditions for its occurrence been defined. In this paper, a winding vibration model incorporating the unidirectional compressive characteristics of spacers was developed to analyse changes in vibration intensity before and after the onset of disk–spacer separation. The study clarified the patterns of separation under varying short‐circuit currents, pre‐tightening forces and spacer hardness. Furthermore, a rapid evaluation method for axial stability was proposed, using disk–spacer separation as a criterion. The results identify the critical conditions for disk–spacer separation, providing a theoretical basis for improving the axial strength of transformer windings.