Research on the Reliability Modeling Method for Low-voltage Switches Based on Competing Failure

The failure of a low-voltage switch is determined by the competition of two failure modes, the degradation failure mode and the random failure mode. According to the failure characteristics and the failure modes of low-voltage switches,this paper proposed a modeling method based on the competing failure process to solve the difficulty in evaluating the reliability of low-voltage switches comprehensively. For the degradation failure mode, the accumulation of contact loss caused by arc erosion was used as the degradation parameter, and the one-dimension Wiener process with linear drift was used to describe the degradation process. And for the random failure mode, the exponential distribution was used to describe the failure process. First, the random failure life were generated by simulation. Second, the accumulation loss due to arc erosion were obtained based on the Wiener process for each life and the competing failure life was calculated. Then, the reliability model based on competing failure was established and the maximum likelihood estimation was used to estimate the model parameters. Finally, three modeling methods based on the degradation failure mode, the random failure mode and the competition of them were tested in simulation to evaluate the reliability of the same failure situation with the two failure modes, and the effectiveness of the competing failure modeling method for evaluating the reliability of low-voltage switches was validated theoretically. Furthermore, the analysis in this paper also shows that, according to the practical demands, one can choose different model to evaluate the reliability of products under different failure situations, which can provide valuable reference for the reliability analysis of low-voltage switches. © 2020 Chin. Soc. for Elec. Eng.