Eleventh International Conference on The Constructed Environment

Abstract

In order to prevent possible defects of power transformers and to avoid losses that occur after taking them out of service, it is important to know the state of their insulation systems. For this purpose, the health index is used, which quantifies the global state of power transformers. To determine power transformers state, a multitude of factors are taken into consideration and a number of tests are conducted, in order to evaluate their global state as accurately as possible. In literature, the health index is calculated based on the model of primary, secondary, and SOS diagnostic methods. In this paper, we discuss how such approaches lack the parameter’s significance based on practical aspects as all tests cannot be performed at the charging of the transformer. It is a new model proposed to have accurate and effective health index scoring. Using the health index, the condition of a power transformer can be assessed. This factor allows the estimation of the remaining transformer lifetime, taking into account some of the most important characteristics of its insulation system. The health index is strongly influenced by the dielectric losses which occur inside electro-insulating components volumes, but also by the conductivity factor and the polarization index.