BENEFICIAL EFFECT OF NATURAL ESTER FLUIDS FOR LIFETIME EXTENSION OF TRANSFORMERS

The environmental loading reduction due to the leakage of the electric insulating oil and the carbon dioxide emissions reduction are recent problems to be solved for the protection of the environment. The studies on the practical use of the natural ester dielectric fluids (vegetable oils) have been performed actively as these countermeasures. This paper presents the experimental results on the aging stability of an insulating paper in rapeseed oil, which has investigated by a heat-accelerated test in the range 90 to 120 ?C in comparison with that in mineral oil. The insulating paper is immersed in the sample oil-filled glass bottle which air gas is flowed in its upper space, and it is taken out after a certain time. A heat-accelerated aging is evaluated by examining the deterioration speed…