Asset management of transformer based on loss of Life calculation

Transformer is one of the critical equipment in the Power distribution system. Transformers are sized and selected according to their connected loads and the load cycles. It can be loaded beyond its name plate rating. A higher load beyond its name plate rating leads to a temperature rise above the specified value which will result in a higher loss of life. The Life of the transformer depends on the life of the insulation, which in turn depends on the hot spot temperature. Transformer life is a well known and predictable phenomenon. Its premature failure can lead to interruption in power supply and a huge loss in a process plant. A transformer sized according to its loss of life has a much predictable life. In some of the installations an upgrade can be avoided if the loss of life can be predicted by calculation. In this paper an attempt is made to demonstrate how an industrial customer checks the adequacy of an existing transformer. A method to size a transformer based on loss of life method which is based on the fundamental heat transfer laws is presented.