Articles techniques et présentations

As reliability of transformer is highly dependable on high voltage condenser type bushing, there is need to design bushings with low dielectric stress to insure the large lifespan of components. It is analytically not possible to predict or analyze the stresses generated at foil edges, tangential stress at core surface, point stresses on stress reliving electrode or nearby ground electrodes. It is design essential to evaluate this parameter to successfully pass type test and reliable operation on field. Low frequency electrostatic standard FEM problem is solved to derive necessary result parameters. Foil used for capacitive grading is of 80-120 micron which has limitation in meshing due to large geometry difference ratio. Sub-model approach where few of the foil edges are simulated to have higher accurate simulation. Guidelines for tangential field on core surface, maximum stress on oil shield, partial discharge inception on foil edges are established through simulation.