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Tunneling of photoexcited carriers in metal oxide varistors
Journal of Applied Physics, 1975ZnO-based ceramic varistors exhibit photocurrents which vary in a highly nonlinear manner with applied voltage. It follows that varistor behavior is controlled by electrical barriers at the ZnO-grain–intergranular-layer interface.
H. R. Philipp, Lionel M. Levinson
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Ageing of metal oxide varistors due to surges
2011 International Symposium on Lightning Protection, 2011Surge arresters are exposed to a series of stresses that trigger changes in their nonlinear behaviors. This paper deals with the ageing of metal oxide varistors concerning the stresses associated to high current short duration surges. The ageing of the samples is evaluated by analyzing the evolution of the resistive component of the leakage current ...
Credson de Salles +2 more
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Metal oxide varistors as surge suppressors
1995 International Conference on Electromagnetic Interference and Compatibility (INCEMIC), 2002High voltage transients and surges are produced due to lightning, inductive load switching, and spikes or electrical noise on power lines. These voltage surges can be as high as 6 kV and the transient period can vary from a few microseconds to milliseconds. The frequencies of these surges vary randomly depending upon the source voltage.
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Surface flashovers on metal-oxide varistor blocks
ICSD'98. Proceedings of the 1998 IEEE 6th International Conference on Conduction and Breakdown in Solid Dielectrics (Cat. No.98CH36132), 2002Extensive studies have been made of surface flashovers on varistor blocks using multipulse (MP currents which simulate multiple stroke lightning ground flashes. The MP results are compared with those obtained with single-pulse (SP) currents and with high temporary overvoltages (TOV) at 50Hz. The blocks used were mostly of 5kA rating as commonly used in
Darveniza Mat, Saha Tapan K.
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Capacitance changes in degraded metal oxide varistors
Proceedings of the 2004 IEEE International Conference on Solid Dielectrics, 2004. ICSD 2004., 2004ZnO based ceramics show a highly nonlinear current-voltage (I-V) characteristic due to intergranular layers at the boundaries of ZnO grains. This research indicates that the junctions formed on the border between ZnO grains and the intergranular phase are responsible for the creation of potential barriers which control the flow of current through the ...
M. Jaroszewski +3 more
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Investigation of various models for metal oxide varistors
Journal of Electronic Materials, 1976A new type of voltage dependent resistors (varistors), based on zinc oxide ceramics with several other metal oxides as additives, has recently been investigated. The microstructure of these varistors consists of ZnO grains surrounded by thin insulating metal oxide barriers.
J. Bernasconi +3 more
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Second-breakdown characteristics of metal-oxide varistors
Journal of Applied Physics, 1977Several new results on the electrical breakdown properties of ZnO-based ceramic varistors are presented. A second-breakdown phenomenon associated with thermal runaway and characterized by a negative differential conductivity was observed in dc tests. The curve of capacitance versus bias current exhibited hysteresis while the I-V characteristics became ...
J. J. Lee, J. K. O’Brien, M. S. Cooper
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Multi-factor ageing of metal oxide varistors
Proceedings of IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP'94), 2002Localised overheating of zinc oxide varistor elements due to the transfer of external leakage currents arising from the incidence of partial electrical discharges (PD) onto their outer surface has been shown to cause premature failure by surface breakdown.
N.M. Vong +3 more
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Microwave Sintering Technology for the Production of Metal Oxide Varistors
MRS Proceedings, 1990ABSTRACTA microwave sintering technology has been developed for the production of metal oxide varistors. The electrical properties (leakage current and non-linearity coefficient) of the microwave sintered devices were found to be comparable to those obtained for conventionally sintered varistors of identical composition.
G. McMahon +4 more
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Long-time polarization currents in metal-oxide varistors
Journal of Applied Physics, 1976The low-frequency (100–10−4 Hz) behavior of metal-oxide varistors is obtained from analysis of the charging and discharging currents which flow upon the application and removal of a step voltage. These results are compared to data for the complex dielectric constant ε=ε′−iε″ obtained using an ac bridge in the frequency range 101–10−1 Hz.
H. R. Philipp, Lionel M. Levinson
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