Effect of Accelearated stresses on Insulation of Power Transformer

The transformers die because of deterioration of insulation with aging. Generally, cellulosic paper and mineral oil form the bulk of insulation in the transformer. The insulation is subjected to a variety of stresses during its operation, such as thermal, electrical, chemical, mechanical, electromagnetic, environmental, etc. Under the influence of the above combined stresses and the presence of oxygen and moisture, the insulation deteriorates continuously over a period of time, eventually lead to failure. The combined stresses may leads to production of byproducts which affects the physical, electrical and chemical properties of the insulation. A number of studies, involving monitoring of one or more parameters of stressed insulation are available in literature which predicts the useful life of transformer. In this research work, the contribution of individual thermal and electrical stresses on the oil and paper insulation of power transformer has been experimentally investigated and examined.