الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Transformers are essential parts in the power system for voltage level conversion and maintaining the power flow in the electrical power system, the stability of which is significant for the reliability of the whole supply. The oil used in all transformers is used for insulating and cooling purposes. Degradation of transformer oil occurs because of the aging, high temperature and chemical reactions such as the oxidation. It is also affected by contaminants from the solid particles. Therefore, the oil condition must be checked regularly and reclaimed or replaced periodically, to avoid the sudden failure of the transformer. In this work, breakdown voltages (BDV) as well as dielectric dissipation factor (Tan δ) at some different oil conditions are measured and analyzed analytically using artificial neural network and distribution function. The effect of temperature variation, particle existence in the oil and the water content are studied. The results explain that the aged oil at 80°C (heated for two hours) provides a good dielectric strength than that fresh oil at ambient temperature. It’s essential that the particles in the oil play an important part for decreasing the BDV as well as giving worst value of tan δ. The experimental results were compared with those from the under operation transformer from the field.