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.