Impulse Life Evaluation of MOV with Median Rank Regression Method Based on Weibull Distribution

The working life evaluation of metal oxide varistors (MOVs) is always expected by MOV manufacturers and users. In Oct. 2019, the International Electrotechnical Commission (IEC) SC37B established a project team PT 61643-333 led by the author of this paper to draft a technical report about MOV life assessment. As an early achievement of PT 61643-333, this paper provides an evaluation method for the impulse life of MOV with the median rank regression (MRR) method based on Weibull distribution. Firstly, the theory of Weibull distribution and the MRR method are introduced. Then the evaluation method and procedure of MOV impulse life is derived from the combination of the MRR method and the impulse characteristics of MOV. Finally, an application example of the proposed evaluation method is given by the test results from real MOV samples.