Reliability Prediction Of Single-phase Smart Meter And Reliability Analysis Of Power Supply Module

Predicting single-phase smart meters' life accurately provides effective reference for meter replacement cycle.Improving single-phase smart meters' reliability ensures normal operation of its functions and designs the single-phase smart meters with high reliability and long service life.All of them have become the hot issues in electric energy metering industry.Taking the single-phase smart meter designed by a company in Xi'an as the research object,this paper carries out the research of reliability prediction method firstly.In the first step,by comparing the prediction method and manual,this paper selects the prediction method(the component stress method)and the prediction manual(the Telcordia SR-332 manual)suitable for the single-phase smart meter.In the second step,based on the prediction method and the prediction manual,the inherent failure rate of different components is analyzed,and the various sensitive stress parameters such as electrical stress and temperature stress are measured and calculated.The mean time to failure(MTTF)of the electric energy meter and the MTTF of each module are obtained by the formula of the working failure rate.Secondly,by analyzing the results of prediction,we find that the failure rate of the power module is higher,and its value is equal to 146.313 FITS.Statistical analysis of the spot data of single-phase smart meter shows that the power module is unable to power up.So this paper takes the power module as the research object to carry out the research on the reliability analysis,and puts forward a reliability analysis method combining failure mode effects and criticality analysis(FMECA)and reliability enhancement test to improve the reliability of the product.The first step of the method is to make quantitative FMECA of the power module based on the failure rate of the power module;and exhaustively analyze the effects of short circuit,open circuit,parameter drift and over stress on the power module of all components;and calculate its hazard degree through the failure rate of each failure mode,barrier mode frequency ratio,fault influence probability and working time.The second step,we analyzes the hazard degree of class?severity failure mode such as transformer T601 short circuit and power supply voltage regulator chip N603 overstress is high.The third step,referring to the calculation process of failure rate of the power module,the cause of the failure of the FMECA form,the calibration flow of the electric energy meter and the analysis of the cause of the failure of the field,selects the temperature stress as the main stress,the electrical stress and the humidity stress as the auxiliary stress to design the reliability enhancement test scheme of the power module.According to the test scheme,the low temperature step test,the high temperature step test and the fast temperature change test are completed,and the potential failure of the power module such as TS2 power chip burnout is found.The last step is to improve the reliability of the power module by analyzing the failure mechanism and improving the circuit such as adding RC filter circuit,increasing isolation distance and adding discharge point.Finally,experiments have proved that the reliability analysis method combining FEMCA with reliability enhancement test can stimulate the product failure effectively and improve the reliability of the product,and has certain engineering application value.