Statistical and Physical Approaches on the Initial Failure Rate of High Voltage Power Transformers

Concerning the failure of power transformer, it is found that the failure rate due to dielectric breakdown decreases in time.. These failures are connected with a possible pollution of the transformer oil by introducing unexpected conductive particles. In this paper, starting from a sample with few data, a proposed Weibull statistical model confirms this decrease. Then, a stochastic model based on a particle extinction process is also developed. Finally, the correlation between the two models makes possible an interpretation of the physical phenomena and the quantification of the parameters which characterize the predictive reliability of power transformers.