Classification of high-voltage varistors into groups of differentiated quality

The research was aimed on defining a factor of quality for high-voltage varistors using Non-Destructive Testing (NDT) techniques, which could be applied during the production testing. The newly proposed parameter Q determined on the basis of the lowest resonant frequency fr measured within the preselected frequency range was taken into account. The parameter Q was defined for ZnO structures after firing, without metallized contacts. The results of investigations allow to conclude that the parameter Q can be used as the quality factor for high-voltage varistors classification into groups of differentiated quality.