Testing And Aging Analysis Of MOV-model SPD

This paper aims to improve on the MOV-model SPD in passing the market and degenerate test, and make an analysis of deterioration and aging on MOV. The MOV-model SPD test in the current specification is much less skillful, that is, no testing to component inside the MOV-model SPD, which the blind spots of test is proposed. Through the actual inspection of the SPD manufacturer, found that some important factors affect the performance of SPD during its production process, such as:MOV package structure, work processes releasejoints and so on, and then proposed the method of opening the module to give a test to these techniques. To combine the method of opening the module test and integration test specification can be more scientific and rational for making the qualified judgments of the MOV-model of SPD, and provide the further protection for the SPD to ingress the market.On account of it is unble to estimate the degradation degree of MOV timely and efficient by U1mA and Ileakage which are the detection parameters of MOV-model SPD in the current, for this reason, it is critical importance for a new method that it is able to estimate the degradation degree of MOV. In the process of the degradation of ZnO varistors, it is necessarily companied by capacitance change, according to the major factors of influence on MOV capacitance and the reasons of the degradation of ZnO varistors, such as Schottky barrier change of the grain boundary and the thoery of ion migration, etc. It has been found that the capacitance of MOV all increased with increasing degradation degree by the experiment of degradate MOV-model SPD in four type tests, which are nominal shocks In, large current shock Imax, thermal stability test and moisture test. In particular, the capacitance of MOV exists approximate linear increase with the increasing impact numbers by the experiment under the impact of the In value. The significance of the capacitance growth could estimate the degradation degree of MOV was first proposed by the experiments. MOV aging is due to the grain boundary characteristics change, which has been proven by the analysis on the reasons of the degradation of MOV, based on the combination of the three parameters,UimA,Ileakage and capacitance.It has been verified the aging mechanism of ion migration by the aging test and analysis.