Novel pulse ageing characteristics of ZPCCE varistor ceramics

The pulse ageing characteristics of the ZnO–Pr6O11–CoO–Cr2O3–Er2O3 varistor ceramics has been investigated for 0.5 and 2.0 mol% Er2O3. The breakdown field (image) increased to almost double when Er2O3 increased from 0.5 to 2.0 mol%. The amount of Er2O3 addition did have a significant effect on clamp ratio, which exhibits a surge protection capability. The varistor ceramics added with 2.0 mol% exhibited the best clamp characteristics, in which the clamp voltage ratio was in the range of K = 1.59–1.84 at a pulse-current of 5–50 A. The varistor ceramics added with 0.5 mol% Er2O3 exhibited excellent electrical stability, where image and %Δα = –10.0% for the pulse-current of 2100 A.