Measurement methods and interpretation algorithms for the determination of the remaining lifetime of the electrical insulation

Measurement methods and interpretation algorithms for the determination of the remaining lifetime of the electrical insulation The paper presents a set of on-line and off-line measuring methods for the dielectric parameters of the electric insulation as well as the method of results interpretation aimed to determine the occurrence of a damage and to set up the its speed of evolution. These results lead finally to the determination of the life time under certain imposed safety conditions. The interpretation of the measurement results is done based on analytical algorithms allowing also the calculation of the index of correlation between the real results and the mathematical interpolation. It is performed a comparative analysis between different measuring and interpretation methods. There are considered certain events occurred during the measurement performance including their causes. The working-out of the analytical methods has been improved during the dielectric measurements performance for about 25 years at a number of 140 turbo and hydro power plants. Finally it is proposed a measurement program to be applied and which will allow the correlation of the on-line and off-line dielectric measurement obtaining thus a reliable technology of high accuracy level for the estimation of the available lifetime of electrical insulation.