Simplified Thermal Computation of a Metal Oxide Varistor Element under a Lightning Impulse Current Injection

Abstract

A simple thermal computation procedure of a metal oxide varistor (MOV) element, in which an impulse current is injected, is presented. The heat in the MOV, composed of many small cells, is computed with the discretized heat transport equation. At each time step, the injected impulse current is assumed to be distributed uniformly in the MOV. The power per cell is computed from the instantaneous values of injected conduction current density and resultant electric field, the latter of which is obtained with an approximate expression of the nonlinear relation between conduction current density and electric field. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.