The surge arrester example presented on these pages is based on a document from the International Electrotechnical Commission (IEC) -- "Guide for the determination of voltage distribution along the length of metal-oxide surge arresters". ElecNet simulation results were compared to some results provided in this document.

The Model - The surge arrester modeled in this example is an arrester with 2 grading rings. It is formed of 2 electrodes: one at the top formed by a conducting metal rod and 2 conducting metal grading rings, and the other at the bottom forming the pedestal of the surge arrester. The potential of the top electrode and grading rings was set to 333 kV. The potential of the pedestal was set to 0. In between the 2 electrodes there are metal-oxide resistors surrounded by a porcelain housing. Metal disks separate the resistor-porcelain units.

This surge arrester was modeled as an axisymmetric, hence 2D, device. The outer radial boundary of the model was set to ground potential.

The Analysis - An electrostatic (Capacitive) simulation of the surge arrester is presented on this page. The metal-oxide resistors were given a relative permittivity of 800, while a permittivity of 5 was chosen for the porcelain housings.