Life prediction of residual current circuit breaker with overcurrent protection based on Tweedie exponential dispersion process with random effects

The residual current circuit breaker with overcurrent protection (RCBO) is essential for maintaining the safety and reliability of low voltage distribution systems. However, the performance of the RCBO can degrade over time, potentially compromising system integrity. Predicting the life of RCBO is critical, but challenging due to the slow degradation under normal operating conditions and the lack of specific evaluation indicators. This study determined that temperature and humidity are the main environmental pressures leading to RCBO failure. To accelerate the degradation process, an accelerated degradation test (ADT) is conducted using the highest levels of temperature and humidity stress. A characteristic quantity reflecting the performance degradation of the RCBO is established based on the results of ADT. Random effects are incorporated into the Tweedie exponential dispersion process model to capture individual differences. This model provides a more accurate fitting of the degradation process compared to commonly used stochastic process models. The point estimate and the interval estimate of the life under each accelerated stress level are obtained based on degradation data. The Peck acceleration model is subsequently utilized to derive the service life under actual temperature and humidity conditions. The results provide references to ensure the RCBO is replaced before degradation leads to failure.