An attempt to identify voltage related non-linearities of transformer insulation from dielectric response measurements

Dielectric response measurement based on polarization and depolarization current are being used these days as a tool for non-destructive testing of transformer insulation. Linear insulation models derived from such measurements are being used by researchers to analyze results and draw inference about insulation condition there from. However, dielectric response of a complex insulation structure such as in a transformer is believed to be non-linear in nature with respect to test conditions. These present contribution reports results of a series of experiments is an attempt to identify such non-linear insulation behavior with respect to excitation voltage.