Axial vibration analysis of transformer windings with hysteresis of stress-and-strain characteristic of insulating materials

This paper deals with the method of calculating the axial vibration of power transformer windings under short circuit conditions. The hysteresis phenomenon is taken into consideration for the stress-and-strain characteristic of insulators in calculating the axial vibration. In order to obtain the hysteresis axes, a repeated load test for typical insulating materials is carried out. At the same time, the influence that compressive speed extends to the modulus of longitudinal elasticity is studied. Measured curves are expressed as a numerical formula and included in the developed method. This method is applied to axial vibration analysis of various transformers that have been normally operating on site, and the relationship between hysteresis characteristics and axial forces, which are compressive force and external thrust force, is discussed in detail. As a result, the proposed method is shown to be a useful means for the axial vibration analysis of transformer winding.