Evaluation of compression behaviors of oil-immersed insulating pressed-boards for transformers

We report on compression behaviors of oil-immersed insulating pressed-boards used in transformers for analyzing the axial vibration of windings. We examined the compression stress-strain curves of oil-immersed pressed-boards. We found that compression behaviors depended on strain rates and temperatures, that is, viscoelastic behaviors were observed. By applying the time-temperature superposition principle to the pressed-boards' compression behaviors, we obtained the relationship between the modulus of compressive elasticity and strain rate. As a result, we were able to estimate the pressed-boards' compression behaviors at high compression forces at high strain rates.