Performance Evaluation of Dielectric Oils Based on Dissolved Gas Analysis and Dissipation Factor Under High-Density Discharge and Partial Discharge Faults

Abstract

Power transformers are critical components within electrical power systems due to their high cost and essential role in maintaining uninterrupted service. Consequently, reducing transformer failure rates is vital, with insulation failures being the primary cause of these faults. Insulating materials, particularly insulating oils in oil-filled transformers, are of significant interest as they provide electrical insulation and facilitate heat dissipation. Various types of oils, notably mineral and ester oils, are employed for this purpose, each exhibiting unique electrical and chemical properties. This study aims to evaluate the performance of these oils under different electrical stresses, including high-density electrical discharge and partial discharge (PD) faults. Four different dielectric oils were prepared and subjected to controlled laboratory tests simulating these fault conditions using specifically designed test cells. Dissolved gas concentrations in each oil are measured and analyzed to establish distinct gas generation patterns under different fault conditions. Additionally, the dielectric dissipation factor (DDF) is measured for each oil, providing a comparative assessment of oil performance under stress. The findings contribute to understanding the quality and reliability of various insulating oils under fault conditions, supporting effective condition monitoring of power transformers.