The modelling and harmonic content of the resistive component of current in ZnO varistors

Recent work on old and failed arresters have shown that there is only a weak correlation between changes in the parameters of an AC model-based on microstructural theories of conduction in ZnO varistors-and high values of the odd harmonics of the resistive component of the varistor leakage current. Here the extrapolation of microstructural theories of conduction for bulk samples is validated. The harmonic components of the leakage current as modelled by the AC power frequency model is found and compared to the experimental data. (4 pages)