Effect of enamel covering of copper conductors in paper oil insulation of transformers

Failure of transformers and reactors due to sulphur in transformer oil is reported in literature. The sulphur in oil by chemical reaction with copper produces copper sulphide which alters the electric field. One of the mitigation techniques followed by manufacturers is replacement of bare copper conductors with enameled copper conductors. In this study, an attempt is made to understand field distribution in transformer insulation due to enamel on the conductor. Finite Element Method (FEM) has been used to understand the electric field distribution in paper and oil with enamel on copper conductor.