Study on the mechanical failure of the cellulosic insulation of continuously transposed conductors in power transformers under the influence of short circuits and thermal ageing

Abstract The dielectric paper of power transformers is subjected to ageing caused by high temperatures and chemical reactions in the oil. electromagnetic forces that affect conductor can cause breakage even end useful life transformer. To improve understanding those phenomena, a continuously transposed with four layers (plain Kraft crepe papers) was impregnated naphthenic oil aged during different periods, representative its whole lifespan. Samples were bending deformations compatible short circuit, cracks generated analysed. mechanically characterised (in tensile, compressive shear modes) tests conductors simulated ANSYS Static Structural, estimate strains paper. Norris failure criterion modified predict regions susceptible fail for particular state deformation level, obtaining good agreement experimental results thus validating this new version approach.