Mean life estimation of metal oxide surge arresters under harmonic distortion

In this paper, similar metal oxide-based arresters are tested using accelerated ageing tests with low and high total harmonic distortion content in the AC voltage stress. The extrapolated ageing times obtained are modelled using the three-parameter Weibull statistical distribution. The hypothesis testing based on the likelihood ratio test is invoked in order to ensure no possibility of equal probability density functions, which are therefore applied to estimate or predict the mean life of MOSA under distorted ac voltage stress. The results obtained indicate that the likelihood ratio test is found to be -1.2855 and the mean life obtained for MOSA samples aged with a total harmonic distortion content of 8.5% in the voltage stress is reduced by 30.13%.