Thermal Aging of Distribution Transformers According to IEEE and IEC Standards

Problems related to the so called "loss of life", or isolation aging of distribution transformers, have been interesting over a long period of time. Since the beginning of the last century various concepts have been used to explain the transformers loss of life and as usual those are interpreted incorrectly. In fact, "loss of life" has always been understood as "reducing the isolation\´s loss of life". There are existing therminological differencess in IEEE and IEC standards, that are used in the methods for determination of ageing in distribution transformers. This paper is comparative analysis between the variables, defined in those standards. The presented analysis relates to a transformer with the following parameters: 630 kVA, 10/0,4 kV, Dy5.