Insulation System optimization in Dry-Type Transformer Using Finite Element Method

Dry-type transformers are the most important equipment of distribution systems in hospitals, military and residential areas that if used properly with necessary cares, they can work safely for more than 20 years. Accordingly, around 30% of all transformer failures are related to insulation breakdown. Finite element method is a powerful and precise tool for the electrical stress analysis in transformer insulating gaps. Therefore in this paper, electrical field distribution is investigated in the transformer insulation gaps. By changing the insulation distances and comparing the maximum electrical field to dielectric strength, the minimum allowable insulation distances are estimated for a typical dry-type transformer. Finally, a refinement is proposed in dry-type transformer insulation systems to reduce the insulating gap between low and high voltage windings and so the net weight of transformer.