Electromagnetic and Thermal Analysis of a ZnO Element of Transmission-Line Arrester for a Lightning Surge Current

The voltage generated across a zinc-oxide (ZnO) element, in which a lightning impulse current flows, has been computed with the finite-difference time-domain (FDTD) method. Also, the distribution of temperature in the ZnO element has been computed on the basis of FDTD-computed conduction current densities with a discretized heat equation. The ZnO element having a thickness of 37 mm and a diameter of 34 mm is represented with many 1 mm x 1 mm x 1 mm cubic cells, each of which has a nonlinear resistivity in each of the x, y, and z directions dependent on the electric field in each direction and the temperature in each cell. Waveforms of voltage appearing across the ZnO element and the temperature on the side surface of the ZnO element computed for a short lightning impulse current having a magnitude of 66 kA agree reasonably well with the corresponding measured ones. (C) 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.