Study On Thermoelectric Characteristics Of Zinc Oxide Varistors

ZnO varistors are important overvoltage protection devices in the field of electronics and information technology,and are critical to the operational safety of electronic and communication systems.It has a long-term leakage current flowing under normal working voltage and aging.After aging,it affects the stable operation of power electronics.Since ZnO varistor is mainly affected by voltage and temperature during operation,it is pressed on the accelerated aging test system.The research on the thermoelectric characteristics of the sensible resistance,the research results provide a meaningful argument for the life assessment of ZnO varistor,with certain theoretical value and engineering practical valueIn this paper,the ZnO varistor AC and DC aging test system is established,which solves the technical difficulty of the ZnO varistor small current region signal difficult to accurately extract,and the shortcomings of long-term manual manual measurement and monitoring Based on Visual Basic software development,the current signal of ZnO varistor and the accurate acquisition of voltage signal applied at both ends of the varistor,data calibration,AC/DC parameter processing and display,database management and report generation are realized.Under the AC voltage in the aging system,the resistive current flowing through the varistor is obtained by the capacitive current harmonic fractionation compensation algorithm in computer programming,and the applied voltage,full current,and resistive current peak of the varistor are realized.Measurement of AC parameters such as capacitive current and power loss;under DC voltage,measurement of DC parameters such as applied voltage,full current,and power loss of the varistor is realizedBased on the ZnO varistor AC and DC accelerated aging test system,the temperature characteristics and charge rate characteristics of ZnO varistor under thermoelectric stress and the variation of aging characteristics under long-term DC voltage were studied.The test result show that:1)Under DC voltage,the leakage current and power loss of ZnO varistor decrease with the increase of the charge rate,while the leakage current and power loss increase with the increase of the charge rate under AC voltage,and Through the varistor aging mechanism,this test phenomenon is compared and analyzed.2)In the long-term DC aging test of varistor,the leakage current of 10K250 varistor has experienced fast under the conditions of 97%charge rate and 145℃ temperature.The three stages of decline,slow rise,and surge;the varistor voltage changes by less than 1%at the point where the varistor leakage current increases sharply(the leakage current increases to 900%of the initial value).The experimental results provide a valuable reference for studying the aging test parameters of ZnO varistor.