A deep insight into ZnO nonlinear resistor

Since its discovery in 1970s , ZnO nonlinear resistor (MOV) has got an extremely wide applications in arrester blocks and low voltage varistors, at the same time some new and deep insights into the MOV´s behavior and properties have been gained , based on which we found that some early understandings of the MOV are not appropriate or incorrect, of which the four following aspects are discussed in this paper: 1 According to the classic definition the varistor is a voltage dependent resistor(VDR), but many facts signified that in macro-property terms it is a current dependent resistor(CDR). 2 Based on the new understanding of CDR, a new resistance formula and V-I characteristic formula of the varistor were found that can accurately express the properties over a wide current range. In addition some early V-I curves in IEC standards and many papers should be revised. 3 Based on the new understanding of CDR, a varistor behavior that is called “ peak displacement” can be well explained.4 Some mistakes related with calculations of power frequency problems are also pointed out in this paper.