Computer simulation of ZnO varistors failures
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy
- Hubbell Power Systems, Centralia, MO (United States)
- Hubbell Inc., The Ohio Brass Co., Wadsworth, OH (United States)
Zinc oxide varistors are multi-component ceramic devices produced by sintering ZnO powder together with small amounts of other oxides. Highly nonlinear current-voltage (I-V) characteristics of ZnO varistors are used in electrical surge arresters. They protect electrical equipment from damage by limiting overvoltages and dissipating the associated energy. Therefore, the energy handling capability is crucial. It is defined as the amount of energy that a varistor can absorb before it fails. Here, a simple thermo-mechanical model is applied to evaluate the influence of the nonuniformity of ZnO varistor disks used in surge arresters on their energy handling capability. By solving heat transfer equations for a varistor disk with nonuniform electrical properties, the authors compute the time dependence of the temperature profile and the distribution of thermal stresses. The model can identify the energy handling limitations of ZnO varistors imposed by three different failure modes: puncture, thermal runaway, and cracking. It conforms to the available failure data, and explains the observation that energy handling improves at high current densities.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 564241
- Report Number(s):
- ORNL/CP-95772; CONF-971201-; ON: DE98001843; BR: KC0202030; TRN: AHC29804%%126
- Resource Relation:
- Conference: 1997 fall meeting of the Materials Research Society, Boston, MA (United States), 1-5 Dec 1997; Other Information: PBD: Nov 1997
- Country of Publication:
- United States
- Language:
- English
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