Zinc oxide varistor is a n type semiconductor with nonlinear voltage characteristics. This non linearity depends on the formation of microstructure which develops in the sintering operation. A computer program has been developed to control this sintering process.
The main two parameters in the sintering operation binder burnout and shrinkage have been controlled through a closed feedback loop using a personal computer. Arrestor blocks with Vnom=5 kV and a diameter of 42mm were sintered using firing profile for different rates of binder burnout (0.375, 0.53 and 0.75 g/kg/h) and shrinkage ( 5, 7.07 and 10 µm/mm/h) and with classical profile. Results were compared for both processes and an optimized sintering profile of binder burnout rate 0.375 g/kg/h and shrinkage rate 5 µm/mm/h has been achieved for improved electrical characteristics.