A study on copper corrosion and its effect on dielectric properties of paper oil insulation of transformers using simulation and laboratory experiments

This study investigates the impact of copper sulphide which is formed due to corrosive sulphur in mineral oil on dielectric properties of paper oil insulation of model transformer windings. The effect of copper sulphide on electric stress distribution is explained using FEM based electric field computations. frequency domain spectroscopy and insulation resistance measurements were carried out on the prototype transformer windings under conditions of copper corrosion at different temperatures and the variations in tan δ, real and imaginary part of complex permittivity (ε’, ε”), insulation resistance, and polarization index are discussed.