Electro-thermal simulation studies for pulsed voltage induced energy absorption and potential failure in microstructured ZnO varistors

G. Zhao, R. P. Joshi, V. K. Lakdawala, H. P. Hjalmarson

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

A time-dependent, two-dimensional model is used to study internal heating effects and possible device failure in ZnO varistors in response to a high-voltage pulse. The physics and qualitative trends discussed here should hold for materials with internal microstructured grain boundaries. Our analysis is based on an electro-thermal, random Voronoi network. It allows for the dynamic predictions of internal failure and to track the progression of hot-spots and thermal stresses. Results here show that application of high voltage pulses can lead to the attainment of Bi2O3 melting temperatures in the grain boundaries and an accelerated progression towards failure. Comparisons between uniform and normally distributed barrier breakdown voltage showed relatively small difference. Physically, this is shown to be associated with the applied bias regime and grain size. It is argued that reduction in grain size would help lower the maximum internal stress. This is thus a desirable feature, and would also work to enhance the hold-off voltage for a given sample size.

Original languageEnglish
Pages (from-to)1007-1015
Number of pages9
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Volume14
Issue number4
DOIs
StatePublished - Aug 2007

Keywords

  • Electro-thermal failure
  • Energy absorption
  • High voltage pulsing
  • Voronoi network
  • ZnO varistor

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