Research On Life Test And Prediction Method Of Earth Leakage Circuit Breaker For Building Power Distribution System

Leakage circuit breakers are important terminal protection appliances in modern building distribution systems.In order to avoid their over-age service and to ensure the safety of people’s lives and property as well as the safe and stable operation of power supply and distribution systems,their ageing laws and life prediction methods need to be studied.Electronic earth leakage circuit breakers are widely used at domestic and international markets,and their leakage protection function relies on the joint cooperation of their internal electronic components,whose performance directly determines whether their leakage protection function is reliable.Through continuous research by scholars domestic and abroad,it has been concluded that the main factor leading to the degradation of the performance of the electronic components inside electronic earth leakage circuit breakers is temperature stress.Considering this,based on the analysis of the working principle and failure mode of electronic earth leakage circuit breakers,this paper designs an accelerated ageing test with temperature as the accelerating stress to obtain complete accelerated ageing test data,and uses the Arrhenius accelerated ageing model to predict its service life under normal temperature stress based on the accelerated ageing test data.In the traditional life evaluation process,the assumptions associated with the modelling and use of accelerated ageing models have not been given sufficient attention,resulting in predictions that deviate from actual service life.In the paper,a life prediction method based on statistical tests is proposed to address the problem.The method addresses the applicability of the Arrhenius accelerated ageing model from statistical theory by means of normality and correlation tests,the consistency of the ageing mechanism of accelerated ageing tests by means of homogeneity of variance test,and the quality of the fitted model by means of residual normality and independence tests and heteroscedasticity tests,which addressed the quality problem of the fitted model and improves the accuracy of the predictive model.Then,by studying the apparent activation energy during the acceleration of electronic leakage circuit breakers,it was found that the apparent activation energy increases with ageing time,while traditional life prediction methods mostly make life prediction directly through a single average apparent activation energy,leading to bias in life assessment.In this paper,the method of life prediction based on the variable apparent activation energy is proposed.The method firstly,the aging process is divided into equal intervals,then the average apparent activation energy of each stage is calculated using the aging time corresponding to each aging process,and the average apparent activation energy of each stage is used to predict the life of each aging process separately.The predicted life of an electronic earth leakage circuit breaker under normal stress is obtained by summing up the life predictions for each ageing process.This method is more relevant to the real ageing process of electronic circuit breakers and the predicted results are closer to their real life.Finally,taking into account the assumptions of the Arrhenius accelerated ageing model and the effect of variable apparent activation energy,the paper uses a comprehensive life prediction method based on statistical tests and variable apparent activation energy to predict the life of electronic earth leakage circuit breakers.The prediction results are similar to the reference life provided by the manufacturer,showing that the method can effectively solve the problems in the life prediction process,and also provide a reference for the life prediction research of other similar products.