Influence of Multiple Trapping Phenomena on The Applications Criteria of ZnO-Bi2O3-Based Varistors

The performance characteristics of the ZnO-Bi2O3-based varistors can be assessed to meet the applicationscriteria on the basis of a systematic evaluation corresponding to various experimental conditions.This evaluation process employs the lumped parameter/complex plane analysis technique for the acsmall-signal immittance data. An overall behavior of these devices is attributed to the microstructuraleffects via controlled grain-size and its distribution, existence of phases, carrier density in the grains,trapping states, and their role within the electrical thickness across the grain-boundary electrical barrier,etc. These factors are strongly dictated by the additives to ZnO in conjunction with the processingvariables. Multiple device functions can result when a single set from a variety of processing parametersis chosen, provided the starting chemistry or composition/formulation remain invariant. The factorsrelated to materials' history, composition recipe, and combined processing methods influence or modifyrelative magnitudes of the constituting elements of each trapping relaxation. Thus, these magnitudeseither increase or decrease the visibility without distorting the devices' generic dielectric behavior. Anidentical set of experiments contributes to distinguish a good varistor performance over a poor responsefor surge arrester (i.e., suppressor/absorber) applications in the power systems' transient protection