New High Performance ZnO-Based Varistors with Rare-Earth Oxides, for Using in Surge Arresters

Traditional ZnO-based varistors, composed of zinc oxide as the main component and about ten other metal oxides, have been widely used as nonlinear resistors in lightning surge arresters, during the past three decades. Nowadays the varistor technology is searching for new varistors with higher threshold voltages, which will enable us to manufacture arresters of smaller size, lighter weight and lower price. In the present work, firstly, varistors with a relatively high Sb2O3 to Bi2O3 ratio of 5 sintered at 12000C were tested and found to have a high threshold voltage (V1mA) of 280 V/mm and a low energyabsorption capacity of 50 J/cm3. The introduction of rare-earth oxides (REO) increased the energy-absorption capacity of Pr6O11- and Nd2O3-doped samples to 110 J/cm3 while their threshold voltage (V1mA) remained slightly above 300V/mm. Thus doping with small amounts of Pr6O11 and Nd2O3 appears to be promising for the preparation of ZnO-based varistors with a high breakdown voltage and a high-energy absorption capacity.

کلیدواژه ها:

ZnO-varistor ، threshold voltage ، rare earth oxides