Investigation on electrical characteristics of dielectric fluids under aging phenomena

In recent years there is a need of alternative insulating fluid for replacing the transformer oil is increased. Owing to the poor biodegradability and availability, vegetable oil has widely replaced the conventional mineral oil used in power apparatus for various applications. Since field investigations may require a longtime progress for observing the aging effects of dielectric materials. In general many researches performed accelerated aging test for predicting the lifetime of liquid dielectrics in laboratory. Partial Discharge (PD) is a vital tool for investigating the insulation degradation of dielectric materials. In this paper, various insulating oil characteristics such as breakdown voltage, viscosity, flash point and fire point are obtained for virgin and thermal aged Mineral oil and Natural ester sample. The result shows that natural ester exhibit good electrical and thermal characteristics than mineral oil.