Analysis of Electromagnetic Forces in DistributionTransformers Under Various Internal Short-Circuit Faults

Internal short circuit faults are the leadingcause of power transformer failures. If notquickly detected, faults usually develop intomore serious faults that would result inirreversible damage to the transformer,unexpected outages and the consequentialcosts. Internal short circuit faults can lead tointensive current in shorted phases andshorted coils. Current increase causesincreasing electromagnetic force intransformer windings. Transientelectromagnetic forces in radial and axialdirections induce critical mechanical stresson windings and transformers. In this paperwe calculate axial and radial electromagneticforce in a three phase core type transformerunder various internal short circuit faults. Wealso investigate effect of location andseverity of internal short fault on axial andradial force. For calculation of forces infaulty transformer, time stepping finiteelement method (TSFE) is used.