Condition and risk assessment of power transformers: a general approach to calculate a Health Index

Abstract

Power transformers are the most important assets in substations and play an important role in the reliability of electrical systems and in the quality of the energy delivered. As the population of transformers in service is getting old, much attention must be focused on transformers availability and reliability. So the condition and risk assessment of the transformers are more and more important to improve the transformers performance, extend their useful life, to decrease costs and to take the best technical and economic decisions, concerning their life cycle management. The “Health Index” was developed to assess and classify transformers based on their condition and to support decisions, concerning refurbishment and replacement. The basic concepts associated to the “Health Index” and to its calculation method are explained here, in a summarized way. An example of the application of this method to a transformer is also given here. Finally, the advantage of the combination of this index with the “Criticality index” is also highlighted.