Overloading analysis of an industrial client distribution transformer in a Portuguese Island

In this paper an analysis is made of the impact of emergency loading made by several inductive loads on the thermal ageing of a distribution transformer belonging to a private industrial client. The analyzed system is a fragment of an isolated electric grid in a Portuguese Island. A transformer thermal model is used to estimate the hot-spot temperature and top-oil temperature given the load ratio. Real data are used for the main inputs of the model, i.e., private industrial client load, transformer parameters and the characteristics of the factory. Finally, a smart transformer protection method is proposed by the authors with the aim of monitoring and protecting it from similar upcoming challenges.