Effects of ZnO varistor degradation on the overvoltage protection mechanism of electronic boards

Yadavari, Hadi; Sal, B; Altun, Mikael; Erturk, E; Ocak, B

doi:10.1201/b19094-282

Cited by 3 publications

(4 citation statements)

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“…This eventually causes a breakdown of protected circuits and components. This phenomenon is demonstrated with the testing of over 100 electronic cards that were commercially used but subsequently failed due to varistor degradation [11]. As a result, to our knowledge, this is the first study on the modeling and characterization of ZnO varistors regarding both degradation processes.…”

Section: Introductionmentioning

confidence: 89%

“…Figure 1. Breakdown of the system in the case of different degradation processes of the ZnO varistor [11].…”

Section: Introductionmentioning

confidence: 99%

“…The reason is that as opposed to an increasing leakage current, a decreasing leakage current might not be hazardous for a varistor. However, we show that this kind of degradation directly affects system reliability and safety [11]. This is illustrated in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…In the literature, there are studies that use AC tests by showing that the Vv parameter of varistors, which is one of the key parameters related to measuring the reliability of a varistor, can be changed during the tests [7,11,14]. In this study, we focus on the reasoning, justification, and modeling of these Vv changes.…”

Section: Introductionmentioning

confidence: 99%

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Distinct degradation processes in ZnO varistors: reliability analysis and modeling with accelerated AC tests

Yadavari¹,

Altun²

2017

Turk J Elec Eng & Comp Sci

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Abstract:In this study, we investigate different degradation mechanisms of zinc oxide (ZnO) varistors. We propose a model that shows how Vv (defined as DC varistor voltage when a 1-mA DC current is applied) changes with time for different stress levels. For this purpose, accelerated degradation tests are applied for different AC current levels and voltage values are then measured. Different from the common practice in the literature that considers degradation with only decreasing Vv values, we demonstrate either an increasing or a decreasing trend in the Vv parameter. The tests show a decreasing trend in Vv for current levels above a certain threshold and an increasing trend for current levels below this threshold. Considering both of these degradation mechanisms, we present a mathematical degradation model.The proposed model exploits the physics of the degradations for a single-grain boundary that is the core structure of a ZnO varistor. To validate the proposed model, we perform Monte Carlo simulations and the results are compared with those obtained from accelerated AC tests. As a summary of this study, we introduce a conceptual accelerated AC test methodology to analyze the reliability of the new ZnO varistor.

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Section: Introductionmentioning

confidence: 89%

“…Figure 1. Breakdown of the system in the case of different degradation processes of the ZnO varistor [11].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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