CHARACTERIZATION OF ZNO SURGE ARRESTER ELEMENTS WITH DIRECT AND POWER FREQUENCY VOLTAGES

An extensive review is given of the published work on the conduction and dielectric properties of ZnO. This work ranges from microscopic studies to high-voltage tests for practical application. The many available equivalent-circuit representations are also described. The DC and AC characteristics of ZnO are known to intersect. The paper presents new test data which show this crossover effect, and provides, for the first time, high-voltage characteristics above the knee of conduction in the frequency range 20-200 Hz. An equivalent-circuit representation is given, based on these new data, which takes account of the crossover effect, the importance of which may not only lie in a hysteresis effect at power frequency, but also in the response of ZnO arresters to fast voltage transients.