Estimation and Analysis of Heat Dissipation Capability of Dielectric Liquids Using Induction Time for Oil-Paper Insulation System

Polarization current measurement is a popular technique for condition assessment of oil-paper insulation systems. However, it is also known to be influenced by the change in measurement temperature. Further, the dielectric liquids serve the specific purpose of heat dissipation in a power transformer. The deterioration of these liquids causes poor heat dissipation and may also lead to severe breakdown of a power transformer. A parameter, induction time estimated from transient temperature-influenced polarization current data, contains crucial information regarding the heat dissipation capability of transformer liquids. This paper presents a comparative analysis of the heat dissipation capability of two different dielectric fluids. The present study considers aged mineral oil and a mixture of old mineral oil and fresh ester in an 80:20 ratio. Along with the estimation and comparative analysis of heat dissipation capability, other dielectric properties such as relative humidity, breakdown strength and viscosity are also compared for the two dielectric liquids.