Reliability Analysis Method of Low‐Voltage Circuit Breakers Based on the Key Failure Modes

Under different service conditions, low‐voltage circuit breakers (LVCBs) present various failure modes, and it is necessary to discriminate these failure modes during reliability analysis. This paper addresses the issue of product reliability analysis under multiple failure modes, proposing a key failure mode discrimination method based on the ratio of the upper and lower limits of product's life (discrimination coefficient). The threshold of this mothed is independent of the failure distribution type, do not rely on expert experience, and are not limited to specific products. The relationship between the key failure modes of LVCBs and the current stresses is studied, and the critical current that causes the transition of key failure modes in LVCBs is researched, which can address the issue of discriminating the key failure modes of LVCBs under different service scenarios. Tests on LVCBs under different current stresses are conducted, and the failure distribution characteristic parameters at different currents are identified. A simplified reliability analysis model for LVCBs based on key failure modes is established. The accuracy of the key failure mode discrimination method and the simplified reliability analysis model is verified, providing a theoretical basis for assessing the reliability of LVCBs under different service conditions. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.