Quality assessment of ZnO-based varistors by 1/f noise

• 1/f Noise can be used as a diagnostic tool of surge arrester varistor structures.
• Noise is a sensitive tool for identification of different grain structures.
• In diagnostics noise gives more distinctive results than DC characteristics.
• Noise data can determine technology parameters of the produced varistors.

Noise has been used as a diagnostic tool of surge arrester varistor structures comprising of ZnO grains of various type and size. The physical and electrical properties of the measured samples have been described. In the experimental study, the applied measurement system and the results of noise measurements for the selected structures of varistors designed for the continuous working voltage 280 V, 440 V and 660 V have been presented. Noise properties are related to electrical characteristics of the measured specimens giving more distinctive results than their voltage–current characteristics. It is suggested that the proposed procedure can be applied as an effective non-destructive testing method focused on defects and structural heterogeneity detection in the tested objects to assess their preparation processes.