Evaluating the Effects of Temperature on Moisture Dynamics and Relaxation Mechanism in Transformer Oil-Paper Insulation

The a ging of paper insulation in a transformer produces <inline-formula> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{O}$ </tex-math></inline-formula> molecules, which ultimately gets released into the oil. Reduced dielectric strength and increased conductivity are the consequences of moisture in insulation. At high temperature, the two main guiding factors that cause dielectric relaxation inside an insulation are electrical polarization and dc conductivity. Polarization and conductivity at high temperature are often difficult to segregate from one another. In the present work, moisture present inside transformer oil-paper insulation is estimated to study its effect on dielectric polarization and conductivity at different operating temperatures. Analysis at various complex planes including complex permittivity, complex susceptibility, complex conductivity, and complex dielectric modulus has been proposed to assess different relaxation distribution processes taking place inside the insulation with varying operating temperature.