Investigation on the equivalent circuit for MOV

The current response for MOV under the step voltages with different amplitudes has been investigated in this paper. A more practical equivalent circuit in the whole current region and the method to determine its corresponding circuit parameters is proposed according to the phenomena that the MOV has polarized current in a low current region and has conducting delay effect in a heavy current region. The current response curves of MOV under different step voltages are given according to the theory analysis and the experiment. In order to obtain the dynamic resistance and the dynamic inductance, the current response curve is formulized quantitatively with the exponent equation when the step voltage is small and the diagrammatizing method is used when the step voltage is larger. The authors obtained the equivalent circuit of MOV mainly consists of four branches: the capacitance branch, two polarized branches (fast-polarized branch and slow-polarized branch) and the nonlinear conducting delay branch.