On the estimation of elapsed life of oil-immersed power transformers

Inadvertent failure of power transformers has serious consequences on the system reliability, economics, and the revenue accrual. An accurate estimation of transformer life can, to a very large extent, mitigate the problems, besides satisfying the conflicting requirements of optimum utilization of the equipment and safeguarding the reliability. In this endeavour, the authors have planned long duration aging experiments on scaled-down (prorated) models of a transformer, incorporating all of the essential features of actual equipment under normal operating electric stress and accelerated thermal stress. In continuation of the authorsʹ earlier experimental investigations, an elapsed life assessment study has been instituted by acquiring insulation-aging data under accelerated thermal stresses.