Trends and outlook for improving transformer assessment during and after transportation

This paper gives an overview of the process of the transformer assessment after transportation. Defective condition, with impact in long-term reliability, is an important concern. Uncertain or false diagnosis is possible and unnecessary tests are often carried out. Transformer acceptance tests include the repetition of some of the factory tests and the Impact recorder data analysis. Acceptance tests also establish a baseline of the electrical and mechanical characteristics that can be used for comparisons throughout the life of the transformer. The FRA method is used to check the possible change in the internal geometry of the active parts of the transformer, displacements, deformations or clamping force loss. In some cases it is impossible to assess the severity of the defects. A new technique for direct measurement of the clamping force is presented. Also, future research and development requirements will be taken into account.